[
    {
        "text": "Isotropic contact forces in arbitrary representation: heterogeneous\n  few-body problems and low dimensions: The Bethe-Peierls asymptotic approach which models pairwise short-range\nforces by contact conditions is introduced in arbitrary representation for\nspatial dimensions less than or equal to 3. The formalism is applied in various\nsituations and emphasis is put on the momentum representation. In the presence\nof a transverse harmonic confinement, dimensional reduction toward\ntwo-dimensional (2D) or one-dimensional (1D) physics is derived within this\nformalism. The energy theorem relating the mean energy of an interacting system\nto the asymptotic behavior of the one-particle density matrix illustrates the\nmethod in its second quantized form. Integral equations that encapsulate the\nBethe-Peierls contact condition for few-body systems are derived. In three\ndimensions, for three-body systems supporting Efimov states, a nodal condition\nis introduced in order to obtain universal results from the Skorniakov\nTer-Martirosian equation and the Thomas collapse is avoided. Four-body bound\nstate eigenequations are derived and the 2D '3+1' bosonic ground state is\ncomputed as a function of the mass ratio.",
        "category": "cond-mat"
    },
    {
        "text": "Modeling neutron and X-ray scattering by liquids: We review exact formalisms for describing the dynamics of liquids in terms of\nstatic parameters. We discuss how these formalisms are prone to suffer from\nimposing restrictions that appear to adhere to common sense but which are\noverly restrictive, resulting in a flawed description of the dynamics of\nliquids. We detail a fail-safe way for modeling the scattering data of liquids\nthat is free from any unwarranted restriction and that models the scattering\nusing the fewest possible number of free parameters. We also list some common\nhabits in analyzing data and how these habits do not do justice to the accuracy\nof the results obtained in scattering experiments, and how these habits may\nstand in the way of rejecting some models used in describing the dynamics of\nliquids.",
        "category": "cond-mat"
    },
    {
        "text": "Origin of the abnormal diffusion of transition metal in rutile: Diffusion of dopants in rutile is the fundamental process that determines the\nperformance of many devices in which rutile is used. The diffusion behavior is\nknown to be highly sample-dependent, but the reasons for this are less well\nunderstood. Here, rutile is studied by using first-principles calculations, in\norder to unravel the microscopic origins of the diverse diffusion behaviors for\ndifferent doping elements. Anomalous diffusion behavior in the open channel\nalong [001] direction is found: larger atoms include Sc and Zr have lower\nenergy barrier for diffusion via interstitial mechanism, apparently\ncontradicting their known slow diffusion rate. To resolve this, we present an\nalternate model for the overall diffusion rate of the large-size dopants in\nrutile, showing that parallel to the [001] channel, it is limited by the\nformation of the interstitial states, whereas in the direction perpendicular to\n[001], it proceeds via a kick-out mechanism. By contrast, Co and Ni, prefer to\nstay in the interstitial site of rutile, and have conventional diffusion with a\nvery small migration barrier in the [001] channel. This leads to highly\nanisotropic and fast diffusion. The diffusion mechanisms found in the present\nstudy can explain the diffusion data measured by experiments, and these\nfindings provide novel understanding for the classic diffusion topic.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of traps on the current impulse from X-ray induced conductivity\n  in wide-gap semiconductors: This article presents a theoretical model for the calculation of the current\nimpulse from X-ray induced conductivity in wide-gap semiconductors that contain\ndifferent types of traps and recombination centres. The absorption of one X-ray\nphoton in a semiconductor with ohmic contacts was investigated. The influence\nof the main parameters of the traps and recombination centres on the shape and\namplitude of the current impulse was determined.",
        "category": "cond-mat"
    },
    {
        "text": "Theoretical analysis of optimization problems - Some properties of\n  random k-SAT and k-XORSAT: This thesis is divided in two parts. The first presents an overview of known\nresults in statistical mechanics of disordered systems and its approach to\nrandom combinatorial optimization problems. The second part is a discussion of\ntwo original results.\n  The first result concerns DPLL heuristics for random k-XORSAT, which is\nequivalent to the diluted Ising p-spin model. It is well known that DPLL is\nunable to find the ground states in the clustered phase of the problem, i.e.\nthat it leads to contradictions with probability 1. However, no solid argument\nsupports this is general. A class of heuristics, which includes the well known\nUC and GUC, is introduced and studied. It is shown that any heuristic in this\nclass must fail if the clause to variable ratio is larger than some constant,\nwhich depends on the heuristic but is always smaller than the clustering\nthreshold.\n  The second result concerns the properties of random k-SAT at large clause to\nvariable ratios. In this regime, it is well known that the uniform distribution\nof random instances is dominated by unsatisfiable instances. A general\ntechnique (based on the Replica method) to restrict the distribution to\nsatisfiable instances with uniform weight is introduced, and is used to\ncharacterize their solutions. It is found that in the limit of large clause to\nvariable ratios, the uniform distribution of satisfiable random k-SAT formulas\nis asymptotically equal to the much studied Planted distribution.\n  Both results are already published and available as arXiv:0709.0367 and\narXiv:cs/0609101 . A more detailed and self-contained derivation is presented\nhere.",
        "category": "cond-mat"
    },
    {
        "text": "Exploring quantum signatures of chaos on a Floquet synthetic lattice: Ergodicity and chaos play an integral role in the dynamical behavior of\nmany-particle systems and are crucial to the formulation of statistical\nmechanics. Still, a general understanding of how randomness and chaos emerge in\nthe dynamical evolution of closed quantum systems remains elusive. Here, we\ndevelop an experimental platform for the realization of canonical quantum\nchaotic Hamiltonians based on quantum simulation with synthetic lattices. We\nmap the angular momentum projection states of an effective quantum spin onto\nthe linear momentum states of a $^{87}$Rb Bose-Einstein condensate, which can\nalternatively be viewed as lattice sites in a synthetic dimension. This\nsynthetic lattice, with local and dynamical control of tight-binding lattice\nparameters, enables new capabilities related to the experimental study of\nquantum chaos. In particular, the capabilities of our system let us tune the\neffective size of our spin, allowing us to illustrate how classical chaos can\nemerge from a discrete quantum system. Moreover, spectroscopic control over our\nsynthetic lattice allows us to explore unique aspects of our spin's dynamics by\nmeasuring the out-of-time-ordered correlation function, and enables future\ninvestigations into entirely new classes of chaotic systems.",
        "category": "cond-mat"
    },
    {
        "text": "Charge accumulation at the boundaries of a graphene strip induced by a\n  gate voltage: Electrostatic approach: Distribution of charge induced by a gate voltage in a graphene strip is\ninvestigated. We calculate analytically the charge profile and demonstrate a\nstrong(macroscopic) charge accumulation along the boundaries of a\nmicrometers-wide strip. This charge inhomogeneity is especially important in\nthe quantum Hall regime where we predict the doubling of the number of edge\nstates and coexistence of two different types of such states. Applications to\ngraphene-based nanoelectronics are discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Dynamics of Coupled Bosonic Wells within the Bose-Hubbard\n  Picture: We relate the quantum dynamics of the Bose-Hubbard model (BHM) to the\nsemiclassical nonlinear equations that describe an array of interacting Bose\ncondensates by implementing a standard variational procedure based on the\ncoherent state method. We investigate the dynamics of the two-site BHM from the\npurely quantum viewpoint by recasting first the model within a spin picture and\nusing then the related dynamical algebra. The latter allows us to study\nthoroughly the energy spectrum structure and to interpret quantally the\nclassical symmetries of the two-site dynamics. The energy spectrum is also\nevaluated through various approximations relying on the coherent state\napproach.",
        "category": "cond-mat"
    },
    {
        "text": "Electronic Transport and quantum oscillation of Topological Semimetals: Three-dimensional (3D) topological semimetals represent a new class of\ntopological matters. The study of this family of materials has been at the\nfrontiers of condensed matter physics, and many breakthroughs have been made.\nSeveral topological semimetal phases, including Dirac semimetals (DSMs), Weyl\nsemimetals (WSMs), nodal-line semimetals (NLSMs), and triple-point semimetals,\nhave been theoretically predicted and experimentally demonstrated. The\nlow-energy excitation around the Dirac/Weyl nodal points, nodal line, or triply\ndegenerated nodal point can be viewed as emergent relativistic fermions.\nExperimental studies have shown that relativistic fermions can result in a rich\nvariety of exotic transport properties, e.g., extremely large\nmagnetoresistance, the chiral anomaly, and the intrinsic anomalous Hall effect.\nIn this review, we first briefly introduce band structural characteristics of\neach topological semimetal phase, then review the current studies on quantum\noscillations and exotic transport properties of various topological semimetals,\nand finally provide a perspective of this area.",
        "category": "cond-mat"
    },
    {
        "text": "Antisite Disorder-induced Exchange Bias Effect in Multiferroic Y2CoMnO6: Exchange bias effect in the ferromagnetic double perovskite compound\nY$_2$CoMnO$_6$, which is also a multiferroic, is reported. The exchange bias,\nobserved below 8~K, is explained as arising due to the interface effect between\nthe ferromagnetic and antiferromagnetic clusters created by {\\it antisite}\ndisorder in this material. Below 8~K, prominent ferromagnetic hysteresis with\nmetamagnetic \"steps\" and significant coercive field, $H_c \\approx$ 10~kOe are\nobserved in this compound which has a $T_c \\approx$ 75~K. A model based on\ngrowth of ferromagnetic domains overcoming the elastic energy of structurally\npinned magnetic interfaces, which closely resembles martensitic-like\ntransitions, is adapted to explain the observed effects. The role of {\\it\nantisite} disorder in creating the domain structure leading to exchange bias\neffect is highlighted in the present work.",
        "category": "cond-mat"
    },
    {
        "text": "Giant anomalous Hall and Nernst conductivities in magnetic all-$d$ metal\n  Heusler alloys: All-$d$ Heuslers are a category of novel compounds combining versatile\nfunctionalities such as caloric responses and spintronics with enhanced\nmechanical properties. Despite the promising transport properties (anomalous\nHall (AHC) and anomalous Nernst (ANC) conductivities) shown in the conventional\nCo$_2$XY Heuslers with $p$-$d$ hybridization, the all-$d$ Heuslers with only\n$d$-$d$ hybridization open a new horizon to search for new candidates with\noutstanding transport properties. In this work, we evaluate the AHC and ANC for\nthermodynamically stable ferro/ferri-magnetic all-$d$-metal regular Heusler\ncompounds based on high-throughput first-principles calculations. It is\nobserved that quite a few materials exhibit giant AHCs and ANCs, such as cubic\nRe$_2$TaMn with an AHC of 2011 S/cm, and tetragonal Pt$_2$CrRh with an AHC of\n1966 S/cm and an ANC of 7.50 A/mK. Comprehensive analysis on the electronic\nstructure reveals that the high AHC can be attributed to the occurrence of the\nWeyl nodes or gapped nodal lines in the neighbourhood of the Fermi level. The\ncorrelations between such transport properties and the number of valence\nelectrons are also thoroughly investigated, which provides a practical guidance\nto tailor AHC and ANC via chemical doping for transverse thermoelectric\napplications.",
        "category": "cond-mat"
    },
    {
        "text": "Charge Transport in a Quantum Electromechanical System: We describe a quantum electromechanical system(QEMS) comprising a single\nquantum dot harmonically bound between two electrodes and facilitating a\ntunneling current between them. An example of such a system is a fullerene\nmolecule between two metal electrodes [Park et al., Nature, 407, 57 (2000)].\nThe description is based on a quantum master equation for the density operator\nof the electronic and vibrational degrees of freedom and thus incorporates the\ndynamics of both diagonal (population) and off diagonal (coherence) terms. We\nderive coupled equations of motion for the electron occupation number of the\ndot and the vibrational degrees of freedom, including damping of the vibration\nand thermo-mechanical noise. This dynamical description is related to\nobservable features of the system including the stationary current as a\nfunction of bias voltage.",
        "category": "cond-mat"
    },
    {
        "text": "Enhanced current noise correlations in a Coulomb-Majorana device: Majorana bound states (MBSs) nested in a topological nanowire are predicted\nto manifest nonlocal correlations in the presence of a finite energy splitting\nbetween the MBSs. However, the signal of the nonlocal correlations has not yet\nbeen detected in experiments. A possible reason is that the energy splitting is\ntoo weak and seriously affected by many system parameters. Here we investigate\nthe charging energy induced nonlocal correlations in a hybrid device of MBSs\nand quantum dots. The nanowire that hosts the MBSs is assumed in proximity to a\nmesoscopic superconducting island with a finite charging energy. Each end of\nthe nanowire is coupled to one lead via a quantum dot with resonant levels.\nWith a floating superconducting island, the devices shows a negative\ndifferential conductance and giant super-Poissonian shot noise, due to the\ninterplay between the nonlocality of the MBSs and dynamical Coulomb blockade\neffect. When the island is strongly coupled to a bulk superconductor, the\ncurrent cross correlations at small lead chemical potentials are negative by\ntuning the dot energy levels. In contrast, the cross correlation is always\npositive in a non-Majorana setup. This difference may provide a signature for\nthe existence of the MBSs.",
        "category": "cond-mat"
    },
    {
        "text": "Five-loop renormalization-group expansions for the three-dimensional\n  n-vector cubic model and critical exponents for impure Ising systems: The renormalization-group (RG) functions for the three-dimensional n-vector\ncubic model are calculated in the five-loop approximation. High-precision\nnumerical estimates for the asymptotic critical exponents of the\nthree-dimensional impure Ising systems are extracted from the five-loop RG\nseries by means of the Pade-Borel-Leroy resummation under n = 0. These\nexponents are found to be: \\gamma = 1.325 +/- 0.003, \\eta = 0.025 +/- 0.01, \\nu\n= 0.671 +/- 0.005, \\alpha = - 0.0125 +/- 0.008, \\beta = 0.344 +/- 0.006. For\nthe correction-to-scaling exponent, the less accurate estimate \\omega = 0.32\n+/- 0.06 is obtained.",
        "category": "cond-mat"
    },
    {
        "text": "On the first Sonine correction for granular gases: We consider the velocity distribution for a granular gas of inelastic hard\nspheres described by the Boltzmann equation. We investigate both the free of\nforcing case and a system heated by a stochastic force. We propose a new method\nto compute the first correction to Gaussian behavior in a Sonine polynomial\nexpansion quantified by the fourth cumulant $a_2$. Our expressions are compared\nto previous results and to those obtained through the numerical solution of the\nBoltzmann equation. It is numerically shown that our method yields very\naccurate results for small velocities of the rescaled distribution. We finally\ndiscuss the ambiguities inherent to a linear approximation method in $a_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Cavity-mediated superconductor$\\unicode{x2013}$ferromagnetic insulator\n  coupling: A recent proof of concept showed that cavity photons can mediate\nsuperconducting (SC) signatures to a ferromagnetic insulator (FI) over a\nmacroscopic distance [Phys. Rev. B, 102, 180506(R) (2020)]. In contrast with\nconventional proximity systems, this facilitates long-distance\nFI$\\unicode{x2013}$SC coupling, local subjection to different drives and\ntemperatures, and studies of their mutual interactions without proximal\ndisruption of their orders. Here we derive a microscopic theory for these\ninteractions, with an emphasis on the leading effect on the FI, namely, an\ninduced anisotropy field. In an arbitrary practical example, we find an\nanisotropy field of $14 \\unicode{x2013} 16$ $\\mu$T, which is expected to yield\nan experimentally appreciable tilt of the FI spins for low-coercivity FIs such\nas Bi-YIG. We discuss the implications and potential applications of such a\nsystem in the context of superconducting spintronics.",
        "category": "cond-mat"
    },
    {
        "text": "Optical Conductivity of the t-J model within Cluster Dynamical Mean\n  Field Theory: We study the evolution of the optical conductivity in the t-J model with\ntemperature and doping using the Extended Dynamical Cluster Approximation. The\ncluster approach results in an optical mass which is doping independent near\nhalf filling. The transition to the superconducting state in the overdoped\nregime is characterized by a decrease in the hole kinetic energy, in contrast\nto the underdoped side where kinetic energy of holes increases upon superfluid\ncondensation. In both regimes, the optical conductivity displays anomalous\ntransfers of spectral weight over a broad frequency region.",
        "category": "cond-mat"
    },
    {
        "text": "Stochastic statistical theory of nucleation and evolution of nano-sized\n  precipitates in alloys with application to precipitation of copper in iron: The consistent and computationally efficient stochastic statistical approach\n(SSA) is suggested to study kinetics of nucleation and evolution of nano-sized\nprecipitates in alloys. An important parameter of the theory is the size of\nlocally equilibrated regions at the nucleation stage which is estimated using\nthe \"maximum thermodynamic gain\" principle suggested.\n  For several realistic models of iron-copper alloys studied, the results of\nthe SSA-based simulations of precipitation kinetics agree well with the kinetic\nMonte Carlo simulation results for all main characteristics of microstructure.\nThe approach developed is also used to study kinetics of nucleation and changes\nin microstructural evolution under variations of temperature or concentration.",
        "category": "cond-mat"
    },
    {
        "text": "Field-induced transition of the magnetic ground state from A-type\n  antiferromagnetic to ferromagnetic order in CsCo2Se2: We report on the magnetic properties of CsCo$_2$Se$_2$ with ThCr$_2$Si$_2$\nstructure, which we have characterized through a series of magnetization and\nneutron diffraction measurements. We find that CsCo$_2$Se2$_2$ undergoes a\nphase transition to an antiferromagnetically ordered state with a N\\'eel\ntemperature of $T_{\\rm N} \\approx$ 66 K. The nearest neighbour interactions are\nferromagnetic as observed by the positive Curie-Weiss temperature of $\\Theta\n\\approx$ 51.0 K. We find that the magnetic structure of CsCo$_2$Se$_2$ consists\nof ferromagnetic sheets, which are stacked antiferromagnetically along the\ntetragonal \\textit{c}-axis, generally referred to as A-type antiferromagnetic\norder. The observed magnitude of the ordered magnetic moment at $T$ = 1.5 K is\nfound to be only 0.20(1)$\\mu_{\\rm Bohr}$/Co. Already in comparably small\nmagnetic fields of $\\mu_0 H_{MM}$(5K) $\\approx$ 0.3 T, we observe a\nmetamagnetic transition that can be attributed to spin-rearrangements of\nCsCo$_2$Se$_2$, with the moments fully ferromagnetically saturated in a\nmagnetic field of $\\mu_0 H_{\\rm FM}$(5K) $\\approx$ 6.4 T. We discuss the entire\nexperimentally deduced magnetic phase diagram for CsCo$_2$Se$_2$ with respect\nto its unconventionally weak magnetic coupling. Our study characterizes\nCsCo$_2$Se$_2$, which is chemically and electronically posed closely to the\n$A_xFe_{2-y}Se_2$ superconductors, as a host of versatile magnetic\ninteractions.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of Fermi surface deformation in a dipolar quantum gas: The deformation of a Fermi surface is a fundamental phenomenon leading to a\nplethora of exotic quantum phases. Understanding these phases, which play\ncrucial roles in a wealth of systems, is a major challenge in atomic and\ncondensed-matter physics. Here, we report on the observation of a Fermi surface\ndeformation in a degenerate dipolar Fermi gas of erbium atoms. The deformation\nis caused by the interplay between strong magnetic dipole-dipole interaction\nand the Pauli exclusion principle. We demonstrate the many-body nature of the\neffect and its tunability with the Fermi energy. Our observation provides basis\nfor future studies on anisotropic many-body phenomena in normal and superfluid\nphases.",
        "category": "cond-mat"
    },
    {
        "text": "Ground state and Spin-Wave dynamics in Brownmillerite SrCoO2.5, A\n  combined Hybrid Functional and LSDAU study: We theoretically investigate the ground state magnetic properties of the\nbrownmillerite phase of SrCoO2.5. Strong correlations within Co d electrons are\ntreated within the local spin density approximations of Density Functional\ntheory (DFT) with Hubbard U corrections (LSDAU) and results are compared with\nthe Heyd Scuzeria Ernzerhof (HSE) functional. The parameters computed with a U\nvalue of 7.5 eV are found to match closely to those computed within the HSE\nfunctional. A G type antiferromagnetic structure is found to be the most stable\none, consistent with experimental observation. By mapping the total energies of\ndifferent magnetic configurations onto a Heisenberg Hamiltonian we compute the\nmagnetic exchange interaction parameters, J, between the nearest neighbor Co\natoms. The J s obtained are then used to compute the spin wave frequencies and\ninelastic neutron scattering intensities. Among four spin wave branches, the\nlowest energy mode was found to have the largest scattering intensity at the\nmagnetic zone center, while the other modes becomes dominant at different\nmomenta. These predictions can be tested by experimentally.",
        "category": "cond-mat"
    },
    {
        "text": "Finite-element dynamic-matrix approach for propagating spin waves:\n  Extension to mono- and multilayers of arbitrary spacing and thickness: In our recent work [AIP Adv. 11, 095006], we presented an efficient numerical\nmethod to compute dispersions and spatial mode profiles of spin waves\npropagating in waveguides with translationally invariant equilibrium\nmagnetization. Using a finite-element method (FEM) allowed to model\ntwo-dimensional waveguide cross sections of arbitrary shape but only finite\nsize. Here, we extend our FEM propagating-wave dynamic-matrix approach from\nfinite waveguides to the important practical cases of infinitely-extended mono-\nand multilayers of arbitrary spacing and thickness. To obtain the mode profiles\nand frequencies, the linearized equation of motion of magnetization is solved\nas an eigenvalue problem only on a one-dimensional line-trace mesh, defined\nalong the normal direction of the layers. Being an important contribution in\nmultilayer systems, we introduce interlayer-exchange interaction into our FEM\napproach. With the calculation of dynamic dipolar fields being the main focus\nof this paper, we also extend the previously presented plane-wave\nFredkin-Koehler method to calculate the dipolar potential of spin waves in\ninfinite layers. The major benefit of this method is that it avoids the\ndiscretization of any non-magnetic material, such as non-magnetic spacers in\nmultilayers. Therefore, the computational effort becomes completely independent\non the spacer thicknesses. Furthermore, it keeps the resulting discretized\neigenvalue problem sparse, which therefore, inherits a comparably low\narithmetic complexity. As a validation of our method (implemented into the\nopen-source finite-element micromagnetic package TetraX), we present results\nfor various systems and compare them with theoretical predictions as well as\nwith established finite-difference numerical methods. We believe this method\noffers an efficient and versatile tool to calculate spin-wave dispersions in\nlayered magnetic systems.",
        "category": "cond-mat"
    },
    {
        "text": "Time-domain pumping a quantum-critical charge-density-wave-ordered\n  material: We determine the exact time-resolved photoemission spectroscopy for a nesting\ndriven charge-density-wave (described by the spinless Falicov-Kimball model\nwithin dynamical mean-field theory). The pump-probe experiment involves two\nlight pulses: the first is an ultrashort intense pump pulse that excites the\nsystem into nonequilibrium, and the second is a lower amplitude higher\nfrequency probe pulse that photoexcites electrons. We examine three different\ncases: the strongly correlated metal, the quantum-critical charge density wave\nand the critical Mott insulator. Our results show that the quantum critical\ncharge density wave has an ultra efficient relaxation channel that allows\nelectrons to be de-excited during the pump pulse, resulting in little net\nexcitation. In contrast, the metal and the Mott insulator show excitations that\nare closer to what one expects from these systems. In addition, the pump field\nproduces spectral band narrowing, peak sharpening, and a spectral gap\nreduction, all of which rapidly return to their field free values after the\npump is over.",
        "category": "cond-mat"
    },
    {
        "text": "A cavity approach to optimization and inverse dynamical problems: In these two lectures we shall discuss how the cavity approach can be used\nefficiently to study optimization problems with global (topological)\nconstraints and how the same techniques can be generalized to study inverse\nproblems in irreversible dynamical processes. These two classes of problems are\nformally very similar: they both require an efficient procedure to trace over\nall trajectories of either auxiliary variables which enforce global\nconstraints, or directly dynamical variables defining the inverse dynamical\nproblems. We will mention three basic examples, namely the Minimum Steiner Tree\nproblem, the inverse threshold linear dynamical problem, and the patient-zero\nproblem in epidemic cascades. All these examples are root problems in\noptimization and inference over networks. They appear in many modern\napplications and in a variety of different contexts. Credit for these results\nshould be shared with A. Braunstein, A. Ramezanpour, F. Altarelli, L.\nDall'Asta, I. Biazzo and A. Lage-Castellanos.",
        "category": "cond-mat"
    },
    {
        "text": "Saddles, Twists, and Curls: Shape Transitions in Freestanding\n  Nanoribbons: Efforts to modulate the electronic properties of atomically thin crystalline\nnanoribbons requires precise control over their morphology. Here, we perform\natomistic simulations on freestanding graphene nanoribbons (GNRs) to first\nidentify the minimal shapes, and then employ a core-edge framework based on\nclassical plate theory to quantify the width dependence in more general\nsystems. The elastic edge-edge interactions force ultra-narrow ribbons to be\nflat, which then bifurcate to twisted and bent shapes at critical widths that\nvary inversely with edge stress. Compressive edge stresses results in twisted\nand saddle shapes that are energetically indistinguishable in the vicinity of\nthe bifurcation. Increasing widths favor the saddle shapes with (longitudinal)\nribbon curvatures that vary non-linearly with width and edge stress. Positive\nedge stresses result in a flat-to-curled transition with similar scalings. At\nlarge widths with negligible edge-edge interactions, rippling instabilities set\nin, i.e. edge ripples and midline dimples for compressive and tensile edge\nstresses. Our results highlight the utility of the core-edge framework in\ndeveloping a unified understanding of the interplay between geometry and\nmechanics that sets the morphology of crystalline nanoribbons.",
        "category": "cond-mat"
    },
    {
        "text": "The stationary SQUID: In the customary mode of operation of a SQUID, the electromagnetic field in\nthe SQUID is an oscillatory function of time. In this situation,\nelectromagnetic radiation is emitted, and couples to the sample. This is a\nback-action that can alter the state that we intend to measure.\n  A circuit that could perform as a stationary SQUID consists of a loop of\nsuperconducting material that encloses the magnetic flux, connected to a\nsuperconducting and to a normal electrode. This circuit does not contain\nJosephson junctions, or any other miniature feature. We study the evolution of\nthe order parameter and of the electrochemical potential in this circuit; they\nconverge to a stationary regime and the voltage between the electrodes depends\non the enclosed flux. We obtain expressions for the power dissipation and for\nthe heat transported by the electric current; the validity of these expressions\ndoes not rely on a particular evolution model for the order parameter. We\nevaluate the influence of fluctuations. For a SQUID perimeter of the order of\n1$\\mu$m and temperature $0.9T_c$, we obtain a flux resolution of the order of\n$10^{-5}\\Phi_0/$Hz$^{1/2}$; the resolution is expected to improve as the\ntemperature is lowered.",
        "category": "cond-mat"
    },
    {
        "text": "Disorder Induced Suppression of CDW Long Range Order: STM Study of\n  Pd-intercalated ErTe3: Pd-intercalated ErTe3 is studied as a model system for the interplay between\na bidirectional two component charge density wave (CDW) state and disorder.\nUsing scanning tunneling microscopy (STM), we show that introducing\nPd-intercalants (i.e. disorder) disrupts the long-range order of both CDW\nstates via the creation of dislocations, which appear associated with each CDW\nseparately. While for weak disorder both CDW states continue to coexist\nthroughout the sample, with no \"domains\" of one CDW direction or another,\nincreasing Pd concentration has a stronger effect on the secondary CDW state,\nmanifested in higher density of dislocations. Vestiges of the two distinct CDW\nphases persist to intercalation levels much above where signatures of the\noriginal phase transition are totally suppressed. This study therefore presents\na first look into the disruption of multiple 2D strong-coupling CDW states by\nthe proliferation of dislocations.",
        "category": "cond-mat"
    },
    {
        "text": "Bias dependent spin injection into graphene on YIG through bilayer hBN\n  tunnel barriers: We study the spin injection efficiency into single and bilayer graphene on\nthe ferrimagnetic insulator Yttrium-Iron-Garnet (YIG) through an exfoliated\ntunnel barrier of bilayer hexagonal boron nitride (hBN). The contacts of two\nsamples yield a resistance-area product between 5 and 30 k$\\Omega\\mu$m$^2$.\nDepending on an applied DC bias current, the magnitude of the non-local spin\nsignal can be increased or suppressed below the noise level. The spin injection\nefficiency reaches values from -60% to +25%. The results are confirmed with\nboth spin valve and spin precession measurements. The proximity induced\nexchange field is found in sample A to be (85 $\\pm$ 30) mT and in sample B\nclose to the detection limit. Our results show that the exceptional spin\ninjection properties of bilayer hBN tunnel barriers reported by Gurram et al.\nare not limited to fully encapsulated graphene systems but are also valid in\ngraphene/YIG devices. This further emphasizes the versatility of bilayer hBN as\nan efficient and reliable tunnel barrier for graphene spintronics.",
        "category": "cond-mat"
    },
    {
        "text": "Quasi One-Dimensional Bosons in Three-dimensional Traps: From Strong\n  Coupling to Weak Coupling Regime: We analyze a recent experiment on a Tonks-Girardeau gas of $^{87}$Rb atoms\n(T. Kinoshita, T. Wenger, and D.S. Weiss, Science {\\bf 305}, 1125 (2004)). We\nfind that the experimental data are compatible with the one-dimensional theory\nof Lieb, Seiringer and Yngvason (Phys. Rev. Lett. {\\bf 91}, 150401 (2003)) but\nare better described by a theory that takes into account variations in the\ntransverse width of the atomic cloud. By using this theory we investigate also\nthe free axial expansion of the $^{87}$Rb gas in different regimes:\nTonks-Girardeau gas, one-dimensional Bose-Einstein condensate and\nthree-dimensional Bose-Einstein condensate.",
        "category": "cond-mat"
    },
    {
        "text": "The Electron Pairing of K$_x$Fe$_{2-y}$Se$_2$: We studied the pairing instabilities in K$_x$Fe$_{2-y}$Se$_2$ using a two\nstage functional renormalization group (FRG) method. Our results suggest the\nleading and subleading pairing symmetries are nodeless $d_{x^2-y^2}$ and nodal\nextended $s$ respectively. In addition, despite having no Fermi surfaces we\nfind the buried hole bands make important contributions to the final effective\ninteraction. From the bandstructure, spin susceptibility and the FRG results we\nconclude that the low energy effective interaction in K$_x$Fe$_{2-y}$Se$_2$ is\nwell described by a $J_1-J_2$ model with dominant nearest-neighbor\nantiferromagnetic interaction $J_1$ (at least as far as the superconducting\npairing is concerned). In the end we briefly mention several obvious\nexperiments to test whether the pairing symmetry is indeed $d_{x^2-y^2}$.",
        "category": "cond-mat"
    },
    {
        "text": "Exact results in the large system size limit for the dynamics of the\n  Chemical Master Equation, a one dimensional chain of equations: We apply the Hamilton-Jacobi equation (HJE) formalism to solve the dynamics\nof the Chemical Master Equation (CME). We found exact analytical expressions\n(in large system-size limit) for the probability distribution, including\nexplicit expression for the dynamics of variance of distribution. We also give\nthe solution for some simple cases of the model with time-dependent rates. We\nderived the results of Van Kampen method from HJE approach using a special\nansatz. Using the Van Kampen method, we give a system of ODE to define the\nvariance in 2-d case. We performed numerics for the CME with stationary noise.\nWe give analytical criteria for the disappearance of bi-stability in case of\nstationary noise in 1-d CME.",
        "category": "cond-mat"
    },
    {
        "text": "Relaxation of Fermionic Excitations in a Strongly Attractive Fermi Gas\n  in an Optical Lattice: We theoretically study the relaxation of high energy single particle\nexcitations into molecules in a system of attractive fermions in an optical\nlattice, both in the superfluid and the normal phase. In a system characterized\nby an interaction scale $U$ and a tunneling rate $t$, we show that the\nrelaxation rate scales as $\\sim Ct\\exp(-\\alpha U^2/t^2)$ in the large $U/t$\nlimit. We obtain explicit expressions for the exponent $\\alpha$, both in the\nlow temperature superfluid phase and the high temperature phase with pairing\nbut no coherence between the molecules. We find that the relaxation rate\ndecreases both with temperature and deviation of the fermion density from\nhalf-filling. We show that quasiparticle and phase degrees of freedom are\neffectively decoupled within experimental timescales allowing for observation\nof ordered states even at high total energy of the system.",
        "category": "cond-mat"
    },
    {
        "text": "Electrodynamics of highly spin-polarized tunnel Josephson junctions: The continuous development of superconducting electronics is encouraging\nseveral studies on hybrid Josephson junctions (JJs) based on\nsuperconductor/ferromagnet/superconductor (SFS) heterostructures, as either\nspintronic devices or switchable elements in quantum and classical circuits.\nRecent experimental evidence of macroscopic quantum tunneling and of an\nincomplete 0-pi transition in tunnel-ferromagnetic spin-filter JJs could\nenhance the capabilities of SFS JJs also as active elements. Here, we provide a\nself-consistent electrodynamic characterization of NbN/GdN/NbN spin-filter JJs\nas a function of the barrier thickness, disentangling the high-frequency\ndissipation effects due to the environment from the intrinsic low-frequency\ndissipation processes. The fitting of the IV characteristics at 4.2K and at\n300mK by using the Tunnel Junction Microscopic model allows us to determine the\nsubgap resistance Rsg, the quality factor Q and the junction capacitance C.\nThese results provide the scaling behavior of the electrodynamic parameters as\na function of the barrier thickness, which represents a fundamental step for\nthe feasibility of tunnel ferromagnetic JJs as active elements in classical and\nquantum circuits, and are of general interest for tunnel junctions other than\nconventional SIS JJs.",
        "category": "cond-mat"
    },
    {
        "text": "Studies of YBCO Strip Lines under Voltage Pulses: Optimisation of the\n  Design of Fault Current Limiters: We present experimental results on the behaviour of a superconducting YBCO/Au\nmeander of length L submitted to short circuit tests with constant voltage\npulses. The meander, at the beginning of the short-circuit, is divided in two\nregions; one, with a length L1 proportional to the applied voltage, which first\nswitches into a highly dissipative state (HDS) while the rest remains\nsuperconducting. Then the rest of the meander will progressively switch into\nthe normal state due to the propagation of this HDS (few m/s) from both ends.\nThe part L1 has to initially support a power density proportional to r.Jp^2 (r\nis the resistivity of the bilayer and Jp the peak current density). To avoid\nlocal excessive dissipation of power and over heating on one part of the wafer\nin the initial period, we have developed a novel design in order to distribute\nthe dissipating section of the meander into many separated small dissipative\nzones. Furthermore the apparent propagation velocity of these dissipative zones\nis increased by the number of propagation fronts. We will show results obtained\non 3kW (300V, 10A) FCL on a 2\" wafer which confirm the benefits of this new\ndesign.",
        "category": "cond-mat"
    },
    {
        "text": "Critical properties of the prethermal Floquet Time Crystal: The critical properties characterizing the formation of the Floquet time\ncrystal in the prethermal phase are investigated analytically in the\nperiodically driven $O(N)$ model. In particular, we focus on the critical line\nseparating the trivial phase with period synchronized dynamics and absence of\nlong-range spatial order from the non-trivial phase where long-range spatial\norder is accompanied by period-doubling dynamics. In the vicinity of the\ncritical line, with a combination of dimensional expansion and exact solution\nfor $N\\to\\infty$, we determine the exponent $\\nu$ that characterizes the\ndivergence of the spatial correlation length of the equal-time correlation\nfunctions, the exponent $\\beta$ characterizing the growth of the amplitude of\nthe order-parameter, as well as the initial-slip exponent $\\theta$ of the aging\ndynamics when a quench is performed from deep in the trivial phase to the\ncritical line. The exponents $\\nu, \\beta, \\theta$ are found to be identical to\nthose in the absence of the drive. In addition, the functional form of the\naging is found to depend on whether the system is probed at times that are\nsmall or large compared to the drive period. The spatial structure of the\ntwo-point correlation functions, obtained as a linear response to a perturbing\npotential in the vicinity of the critical line, is found to show algebraic\ndecays that are longer ranged than in the absence of a drive, and besides being\nperiod-doubled, are also found to oscillate in space at the wave-vector\n$\\omega/(2 v)$, $v$ being the velocity of the quasiparticles, and $\\omega$\nbeing the drive frequency.",
        "category": "cond-mat"
    },
    {
        "text": "Ferroelectric nanodomains in epitaxial PbTiO3 films grown on SmScO3 and\n  TbScO3 substrates: Domain structures of 320 nm thin epitaxial films of ferroelectric PbTiO3\ngrown by MOCVD technique in identical conditions on SmScO3 and TbScO3\nperovskite sub- strates have been investigated by Raman spectroscopy and\npiezoresponse force microscopy techniques. Phonon frequency shifts and typical\ndomain structure motifs are discussed. The results reveal strikingly different\ndomain structure architecture: domain structures of the PbTiO3 film grown on\nSmScO3 have dominantly a-domain orientation while strongly preferential\nc-domain orientation was found in the PbTiO3 film grown on the TbScO3\nsubstrate. Differences between the two cases are traced back to the\nfilm-substrate lattice mismatch at the deposition temperature.",
        "category": "cond-mat"
    },
    {
        "text": "High Contrast X-ray Speckle from Atomic-Scale Order in Liquids and\n  Glasses: The availability of ultrafast pulses of coherent hard x-rays from the Linac\nCoherent Light Source opens new opportunities for studies of atomic-scale\ndynamics in amorphous materials. Here we show that single ultrafast coherent\nx-ray pulses can be used to observe the speckle contrast in the high-angle\ndiffraction from liquid Ga and glassy Ni2Pd2P and B2O3. We determine the\nthresholds above which the x-ray pulses disturb the atomic arrangements.\nFurthermore, high contrast speckle is observed in scattering patterns from the\nglasses integrated over many pulses, demonstrating that the source and optics\nare sufficiently stable for x-ray photon correlation spectroscopy studies of\ndynamics over a wide range of time scales.",
        "category": "cond-mat"
    },
    {
        "text": "Comparative evaluation of catalyst materials using a binary choice model: Advances in algorithms and hardware have enabled computers to design new\nmaterials atom-by-atom. However, in order for these computer-generated\nmaterials to truly address problems of societal importance, such as clean\nenergy generation, it is not enough for them to have superior physical\nproperties. It is also important for them to be adopted by as many users as\npossible. In this paper, we present a simple binary choice model for comparing\ncatalyst materials on the basis of consumer preferences. This model considers a\npopulation of utility maximisers who select one of two materials by comparing\ncatalytic turnover rates with sales prices. Through a mixture of numerical\nsimulation and analytic theorems, we characterise the predictions of the model\nin a variety of regimes of consumer behavior. We also show how the model can be\nused as a guide for crafting policies for lowering catalyst prices in order to\nimprove their market shares. This work represents a first step towards\nunderstanding how material properties should be balanced against production\ncosts and consumer demand when designing new materials, an intellectual advance\nwhich may facilitate the spread of green materials in society.",
        "category": "cond-mat"
    },
    {
        "text": "Fast computation of magnetostatic fields by Non-uniform Fast Fourier\n  Transforms: The bottleneck of micromagnetic simulations is the computation of the\nlong-ranged magnetostatic fields. This can be tackled on regular N-node grids\nwith Fast Fourier Transforms in time N logN, whereas the geometrically more\nversatile finite element methods (FEM) are bounded to N^4/3 in the best case.\nWe report the implementation of a Non-uniform Fast Fourier Transform algorithm\nwhich brings a N logN convergence to FEM, with no loss of accuracy in the\nresults.",
        "category": "cond-mat"
    },
    {
        "text": "A Frequency-Controlled Magnetic Vortex Memory: Using the ultra low damping NiMnSb half-Heusler alloy patterned into\nvortex-state magnetic nano-dots, we demonstrate a new concept of non-volatile\nmemory controlled by the frequency. A perpendicular bias magnetic field is used\nto split the frequency of the vortex core gyrotropic rotation into two distinct\nfrequencies, depending on the sign of the vortex core polarity $p=\\pm1$ inside\nthe dot. A magnetic resonance force microscope and microwave pulses applied at\none of these two resonant frequencies allow for local and deterministic\naddressing of binary information (core polarity).",
        "category": "cond-mat"
    },
    {
        "text": "Emergent isotropy of a wave-turbulent cascade in the Gross-Pitaevskii\n  model: The restoration of symmetries is one of the most fascinating properties of\nturbulence. We report a study of the emergence of isotropy in the\nGross-Pitaevskii model with anisotropic forcing. Inspired by recent\nexperiments, we study the dynamics of a Bose-Einstein condensate in a\ncylindrical box driven along the symmetry axis of the trap by a spatially\nuniform force. We introduce a measure of anisotropy $A(k,t)$ defined on the\nmomentum distributions $n(\\boldsymbol{k},t)$, and study the evolution of\n$A(k,t)$ and $n(\\boldsymbol{k},t)$ as turbulence proceeds. As the system\nreaches a steady state, the anisotropy, large at low momenta because of the\nlarge-scale forcing, is greatly reduced at high momenta. While\n$n(\\boldsymbol{k},t)$ exhibits a self-similar cascade front propagation,\n$A(k,t)$ decreases without such self-similar dynamics. Finally, our numerical\ncalculations show that the isotropy of the steady state is robust with respect\nto the amplitude of the drive.",
        "category": "cond-mat"
    },
    {
        "text": "First-principles prediction of mechanical and bonding characteristics of\n  new T2 superconductor Ta5GeB2: In the present paper, DFT (Density Functional Theory) based first-principles\nmethods are applied to investigate the mechanical and bonding properties of\nnewly synthesized T2 phase superconductor Ta5GeB2 for the first time. The\ncalculated lattice constants are in reasonable agreement with the experiment.\nThe elastic constants (Cij), bulk modulus (B), shear modulus (G), Young's\nmodulus (Y), Poisson ratio (nu), Pugh ratio (G/B), and elastic anisotropy\nfactor, A, of Ta5GeB2 are calculated to explore the mechanical behavior of the\ncompound.To give an explanation of the bonding nature of this new ternary\ntetragonal system, the band structure, density of states, and Mulliken atomic\npopulation are investigated. The estimated Debye temperature and Vickers\nhardness are also used to justify both the mechanical and bonding properties of\nTa5GeB2.",
        "category": "cond-mat"
    },
    {
        "text": "Giant effective Zeeman splitting in a monolayer semiconductor realized\n  by spin-selective strong light-matter coupling: Strong coupling between light and the fundamental excitations of a\ntwo-dimensional electron gas (2DEG) are of foundational importance both to pure\nphysics and to the understanding and development of future photonic\nnanotechnologies. Here we study the relationship between spin polarization of a\n2DEG in a monolayer semiconductor, MoSe$_2$, and light-matter interactions\nmodified by a zero-dimensional optical microcavity. We find robust\nspin-susceptibility of the 2DEG to simultaneously enhance and suppress\ntrion-polariton formation in opposite photon helicities. This leads to\nobservation of a giant effective valley Zeeman splitting for trion-polaritons\n(g-factor >20), exceeding the purely trionic splitting by over five times.\nGoing further, we observe robust effective optical non-linearity arising from\nthe highly non-linear behaviour of the valley-specific strong light-matter\ncoupling regime, and allowing all-optical tuning of the polaritonic Zeeman\nsplitting from 4 to >10 meV. Our experiments lay the groundwork for engineering\nquantum-Hall-like phases with true unidirectionality in monolayer\nsemiconductors, accompanied by giant effective photonic non-linearities rooted\nin many-body exciton-electron correlations.",
        "category": "cond-mat"
    },
    {
        "text": "Kinetic Monte Carlo modelling of Helium Bubble Nucleation onto Oxides in\n  the Fe-Ti-Y-O System: A Kinetic Monte Carlo (KMC) model was created to simulate the insertion of\ntransmutation He atoms into nanostructured ferritic alloys (NFAs) under neutron\nirradiation. Interstitial He atoms migrate through the NFA until becoming\ntrapped in bubbles of other He atoms and vacancies created from irradiation.\nThe Y-Ti-O nano-oxides in the NFAs were found to be effective in capturing\nthese He atoms and preventing bubbles from forming at the grain boundary and\nappear to replicate the characteristics (size and number density) observed in\nother experiments. The bubbles were found to prefer the <111> oxide interface\nas a nucleation site and the stable bubbles have a He/Vac ratio between 1.3 and\n1.8 He/Vac. The influence of He bubbles on the segregation of solutes to the\ngrain boundaries or on the stability of the nano-oxides were negligible.",
        "category": "cond-mat"
    },
    {
        "text": "Probing the role of single defects on the thermodynamics of\n  electric-field induced phase transitions: The kinetics and thermodynamics of first order transitions is universally\ncontrolled by defects that act as nucleation sites and pinning centers. Here we\ndemonstrate that defect-domain interactions during polarization reversal\nprocesses in ferroelectric materials result in a pronounced fine structure in\nelectromechanical hysteresis loops. Spatially-resolved imaging of a single\ndefect center in multiferroic BiFeO3 thin film is achieved, and the defect size\nand built-in field are determined self-consistently from the single-point\nspectroscopic measurements and spatially-resolved images. This methodology is\nuniversal and can be applied to other reversible bias-induced transitions\nincluding electrochemical reactions.",
        "category": "cond-mat"
    },
    {
        "text": "The origin of insulating and non-ferromagnetic SrRuO3 monolayers: The electro-magnetic properties of ultrathin epitaxial ruthenate films have\nlong been the subject of debate. Here we combine experimental with theoretical\ninvestigations of (SrTiO3)5-(SrRuO3)n-(SrTiO3)5 (STO5-SROn-STO5)\nheterostructures with n = 1 and 2 unit cells, including extensive\natomic-resolution scanning-transmission-electron-microscopy imaging,\nelectron-energy-loss-spectroscopy chemical mapping, as well as transport and\nmagneto-transport measurements. The experimental data demonstrate that the\nSTO5-SRO2-STO5 heterostructure is stoichiometric, metallic, and ferromagnetic\nwith TC ~ 128 K, even though it lacks the characteristic bulk-SRO octahedral\ntilts and matches the cubic STO structure. In contrast, the STO5-SRO1-STO5\nheterostructure features Ru-Ti intermixing in the RuO2 layer, also without\noctahedral tilts, but is accompanied by a loss of metallicity and\nferromagnetism. Density-functional-theory calculations show that stoichiometric\nn = 1 and n = 2 heterostructures are metallic and ferromagnetic with no\noctahedral tilts, while non-stoichiometry in the Ru sublattice in the n = 1\ncase opens an energy gap and induces antiferromagnetic ordering. Thus, the\nresults indicate that the observed non-stoichiometry is the cause of the\nobserved loss of metallicity and ferromagnetism in the n = 1 case.",
        "category": "cond-mat"
    },
    {
        "text": "Control of Multi-level Voltage States in a Hysteretic SQUID\n  Ring-Resonator System: In this paper we study numerical solutions to the quasi-classical equations\nof motion for a SQUID ring-radio frequency (rf) resonator system in the regime\nwhere the ring is highly hysteretic. In line with experiment, we show that for\na suitable choice of of ring circuit parameters the solutions to these\nequations of motion comprise sets of levels in the rf voltage-current dynamics\nof the coupled system. We further demonstrate that transitions, both up and\ndown, between these levels can be controlled by voltage pulses applied to the\nsystem, thus opening up the possibility of high order (e.g. 10 state),\nmulti-level logic and memory.",
        "category": "cond-mat"
    },
    {
        "text": "PT breaking and RG flows between multicritical Yang-Lee fixed points: We study a novel class of Renormalization Group flows which connect\nmulticritical versions of the two-dimensional Yang-Lee edge singularity\ndescribed by the conformal minimal models M(2,2n+3). The absence in these\nmodels of an order parameter implies that the flows towards and between\nLee-Yang edge singularities are all related to the spontaneous breaking of PT\nsymmetry and comprise a pattern of flows in the space of PT symmetric theories\nconsistent with the c-theorem and the counting of relevant directions.\nAdditionally, we find that while in a part of the phase diagram the domains of\nunbroken and broken PT symmetry are separated by critical manifolds of class\nM(2,2n+3), other parts of the boundary between the two domains are not\ncritical.",
        "category": "cond-mat"
    },
    {
        "text": "Electric field-induced creation and directional motion of domain walls\n  and skyrmion bubbles: Magnetization dynamics driven by an electric field could provide long-term\nbenefits to information technologies because of its ultralow power consumption.\nMeanwhile, the Dzyaloshinskii-Moriya interaction in interfacially asymmetric\nmultilayers consisting of ferromagnetic and heavy-metal layers can stabilize\ntopological spin textures, such as chiral domain walls, skyrmions, and skyrmion\nbubbles. These topological spin textures can be controlled by an electric\nfield, and hold promise for building advanced spintronic devices. Here, we\npresent an experimental and numerical study on the electric field-induced\ncreation and directional motion of topological spin textures in magnetic\nmultilayer films and racetracks with thickness gradient and interfacial\nDzyaloshinskii-Moriya interaction at room temperature. We find that the\nelectric field-induced directional motion of chiral domain wall is accompanied\nwith the creation of skyrmion bubbles at certain conditions. We also\ndemonstrate that the electric field variation can induce motion of skyrmion\nbubbles. Our findings may provide opportunities for developing skyrmion-based\ndevices with ultralow power consumption.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetoelastic study on the frustrated quasi-one-dimensional spin-1/2\n  magnet LiCuVO$_4$: We investigated the magnetoelastic properties of the quasi-one-dimensional\nspin-1/2 frustrated magnet LiCuVO$_4$. Longitudinal-magnetostriction\nexperiments were performed at 1.5 K in high magnetic fields of up to 60 T\napplied along the $b$ axis, i.e., the spin-chain direction. The\nmagnetostriction data qualitatively resemble the magnetization results, and\nsaturate at $H_{\\text{sat}} \\approx 54$ T, with a relative change in sample\nlength of $\\Delta L/L \\approx 1.8\\times10^{-4}$. Remarkably, both the\nmagnetostriction and the magnetization evolve gradually between $H_{\\text{c3}}\n\\approx 48$ T and $H_{\\text{sat}}$, indicating that the two quantities\nconsistently detect the spin-nematic phase just below the saturation. Numerical\nanalyses for a weakly coupled spin-chain model reveal that the observed\nmagnetostriction can overall be understood within an exchange-striction\nmechanism. Small deviations found may indicate nontrivial changes in local\ncorrelations associated with the field-induced phase transitions.",
        "category": "cond-mat"
    },
    {
        "text": "Nanotransfer Printing of Organic and Carbon Nanotube Thin-Film\n  Transistors on Plastic Substrates: A printing process for high-resolution transfer of all components for organic\nelectronic devices on plastic substrates has been developed and demonstrated\nfor pentacene (Pn), poly (3-hexylthiophene) and carbon nanotube (CNT) thin-film\ntransistors (TFTs). The nanotransfer printing process allows fabrication of an\nentire device without exposing any component to incompatible processes and with\nreduced need for special chemical preparation of transfer or device substrates.\nDevices on plastic substrates include a Pn TFT with a saturation, field-effect\nmobility of 0.09 cm^2 (Vs)^-1 and on/off ratio approximately 10^4 and a CNT TFT\nwhich exhibits ambipolar behavior and no hysteresis.",
        "category": "cond-mat"
    },
    {
        "text": "Atomistic Modelling of Energy Dissipation in Nanoscale Gears: Molecule- and solid-state gears build the elementary constituents of\nnanoscale mechanical machineries. Recent experimental advances in fabrication\ntechnologies in the field have strongly contributed to better delineate the\nroadmap towards the ultimate goal of engineering molecular-scale mechanical\ndevices. To complement experimental studies, computer simulations play an\ninvaluable role, since they allow to address, with atomistic resolution,\nvarious fundamental issues such as the transmission of angular momentum in\nnanoscale gear trains and the mechanisms of energy dissipation at such length\nscales. We review in this chapter our work addressing the latter problem. Our\ncomputational approach is based on classical atom-istic Molecular Dynamics\nsimulations. Two basic problems are discussed: (i) the dominant energy\ndissipation channels of a rotating solid-state nanogear adsorbed on a surface,\nand (ii) the transmission of rotational motion and frictional processes in a\nheterogeneous gear pair consisting of a graphene nanodisk and a molecular-scale\ngear.",
        "category": "cond-mat"
    },
    {
        "text": "Finite-temperature trapped dipolar Bose gas: We develop a finite temperature Hartree theory for the trapped dipolar Bose\ngas. We use this theory to study thermal effects on the mechanical stability of\nthe system and density oscillating condensate states. We present results for\nthe stability phase diagram as a function of temperature and aspect ratio. In\noblate traps above the critical temperature for condensation we find that the\nHartree theory predicts significant stability enhancement over the\nsemiclassical result. Below the critical temperature we find that thermal\neffects are well described by accounting for the thermal depletion of the\ncondensate. Our results also show that density oscillating condensate states\noccur over a range of interaction strengths that broadens with increasing\ntemperature.",
        "category": "cond-mat"
    },
    {
        "text": "Interactions and screening in gated bilayer graphene nanoribbons: The effects of Coulomb interactions on the electronic properties of bilayer\ngraphene nanoribbons (BGNs) covered by a gate electrode are studied\ntheoretically. The electron density distribution and the potential profile are\ncalculated self-consistently within the Hartree approximation. A comparison to\ntheir single-particle counterparts reveals the effects of interactions and\nscreening. Due to the finite width of the nanoribbon in combination with\nelectronic repulsion, the gate-induced electrons tend to accumulate along the\nBGN edges where the potential assumes a sharp triangular shape. This has a\nprofound effect on the energy gap between electron and hole bands, which\ndepends nonmonotonously on the gate voltage and collapses at intermediate\nelectric fields. We interpret this behavior in terms of interaction-induced\nwarping of the energy dispersion.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of pressure on the electronic and magnetic properties of\n  CdV$_2$O$_4$: Density functional theory studies: We investigate the effect of pressure on the electronic and magnetic states\nof CdV$_2$O$_4$ by using ab initio electronic structure calculations. The\nCoulomb correlation and spin-orbit coupling play important role in deciding the\nstructural, electronic and magnetic properties of the compound. The total\nmagnetic moment of V ion is found to be $\\sim$1.3 $\\mu_B$ and making an angle\nof $\\sim$9.5 degree with the z-axis. In the tetragonal phase, the ground state\nis the orbital ordered state where V $d_{xz}$ and $d_{yz}$ obtitals are mainly\noccupied at the neighbouring sites. This work predicts the electronic phase\ntransition from orbital-ordered-insulator to orbital-ordered-metal to\norbital-disordered-metal with increasing pressure. The pressure induced\nbroadening of lower and upper Hubbard bands gives rise to metal-insulator\ntransition above 35 GPa. The simple mean-field theory used in the present work\nis able to describe the pressure dependent variation of the antiferromagnetic\ntransition temperature suggesting the applicability of the method in the study\nof the magnetic behaviour of similar geometrically frustrated systems.",
        "category": "cond-mat"
    },
    {
        "text": "Enhanced magnetism, memory and aging in Gold-Iron oxide nanoparticle\n  composites: In this report we present systematic magnetic studies of pure iron oxide\nnanoparticles and gold iron oxide nanocomposite with increasing Au particle\nsize/content. For the magnetic studies of these samples we have measured: (1)\nzero field cooled (ZFC) and field cooled (FC) magnetization, (2) ac\nsusceptibility, (3) magnetization vs field at various temperatures, (4)\nthermoremanant magnetization relaxation (TRM) and zero field cooled\nmagnetization relaxation (ZFCM) at fixed temperature for various wait times tw\nfor studying the aging effect, (5) magnetization memory effect and (6) exchange\nbias as a function of cooling field. The detailed magnetic measurement analysis\nindicates that the pure Fe3O4 nanoparticles sample behaves like a\nsuperparamagnet and on incorporation of gold (Au) nanoparticles the\nnanocomposite system slowly evolves from superparamagnetic to superspin glass\nstate. The memory and aging effect enhances with the increase of the Au\nnanoparticle size/content. The most important observation in this study is the\nenhancement of magnetization with the incorporation of Au nanoparticles. The\nenhancement increases with the increase in the Au content in the nanocomposite.\nWe have explained the cause of this enhancement of magnetization as due to\nlarge orbital magnetic moment formation at the Au/magnetic particle interface.",
        "category": "cond-mat"
    },
    {
        "text": "Anderson Localization of cold atomic gases with effective spin-orbit\n  interaction in a quasiperiodic optical lattice: We theoretically investigate the localization properties of a spin-orbit\ncoupled spin-1/2 particle moving in a one-dimensional quasiperiodic potential,\nwhich can be experimentally implemented using cold atoms trapped in a\nquasiperiodic optical lattice potential and external laser fields. We present\nthe phase diagram in the parameter space of the disorder strength and those\nrelated to the spin-orbit coupling. The phase diagram is verified via\nmultifractal analysis of the atomic wavefunctions and the numerical simulation\nof diffusion dynamics. We found that spin-orbit coupling can lead to the\nspectra mixing (coexistence of extended and localized states) and the\nappearance of mobility edges.",
        "category": "cond-mat"
    },
    {
        "text": "Mesoscopic Tunneling Magnetoresistance: We study spin-dependent transport through\nferromagnet/normal-metal/ferromagnet double tunnel junctions in the mesoscopic\nCoulomb blockade regime. A general transport equation allows us to calculate\nthe conductance in the absence or presence of spin-orbit interaction and for\narbitrary orientation of the lead magnetizations. The tunneling\nmagnetoresistance (TMR), defined at the Coulomb blockade conductance peaks, is\ncalculated and its probability distribution presented. We show that mesoscopic\nfluctuations can lead to the optimal value of the TMR.",
        "category": "cond-mat"
    },
    {
        "text": "Level compressibility in a critical random matrix ensemble: The second\n  virial coefficient: We study spectral statistics of a Gaussian unitary critical ensemble of\nalmost diagonal Hermitian random matrices with off-diagonal entries\n$<|H_{ij}|^{2} > \\sim b^{2} |i-j|^{-2}$ small compared to diagonal ones\n$<|H_{ii}|^{2} > \\sim 1$. Using the recently suggested method of {\\it virial\nexpansion} in the number of interacting energy levels (J.Phys.A {\\bf 36},8265\n(2003)), we calculate a coefficient $\\propto b^{2}\\ll 1$ in the level\ncompressibility $\\chi(b)$. We demonstrate that only the leading terms in\n$\\chi(b)$ coincide for this model and for an exactly solvable model suggested\nby Moshe, Neuberger and Shapiro (Phys.Rev.Lett. {\\bf 73}, 1497 (1994)), the\nsub-leading terms $\\sim b^{2}$ being different. Numerical data confirms our\nanalytical calculation.",
        "category": "cond-mat"
    },
    {
        "text": "Tuning the Hysteresis of a Metal-Insulator Transition via Lattice\n  Compatibility: Structural phase transitions serve as the basis for many functional\napplications including shape memory alloys (SMAs), switches based on\nmetal-insulator transitions (MITs), etc. In such materials, lattice\nincompatibility between phases often results in a thermal hysteresis, which is\nintimately tied to degradation of reversibility of the transformation. The\nnon-linear theory of martensite suggests that the hysteresis of a martensitic\nphase transformation is solely determined by the lattice constants, and the\nconditions proposed for geometrical compatibility have been successfully\napplied to minimizing the hysteresis in SMAs. In this work, we apply the\nnon-linear theory to a strongly correlated oxide system (W doped VO2), and show\nthat the hysteresis of the MIT in the system can be directly tuned by adjusting\nthe lattice constants of the phases. The results underscore the profound\ninfluence structural compatibility has on intrinsic electronic properties, and\nindicate that the theory provides a universal guidance for optimizing phase\ntransforming materials.",
        "category": "cond-mat"
    },
    {
        "text": "Oscillating spin-orbit interaction as a source of spin-polarized wave\n  packets in two-terminal nanoscale devices: Ballistic transport through nanoscale devices with time-dependent Rashba-type\nspin-orbit interaction (SOI) can lead to spin-polarized wave packets that\nappear even for completely unpolarized input. The SOI that oscillates in a\nfinite domain generates density and spin polarization fluctuations that leave\nthe region as propagating waves. Particularly, spin polarization has space and\ntime dependence even in regions without SOI. Our results are based on an\nanalytic solution of the time-dependent Schr\\\"odinger equation. The relevant\nFloquet quasi-energies that are obtained appear in the energy spectrum of both\nthe transmitted and reflected waves.",
        "category": "cond-mat"
    },
    {
        "text": "Dopant-Induced Local Pairing Inhomogeneity in\n  Bi$_2$Sr$_2$CaCu$_2$O$_{8+\u03b4}$: A new theoretical model is presented to study the nanoscale electronic\ninhomogeneity in high-$T_c$ cuprates. In this model, we argue that the randomly\ndistributed out-of-plane interstitial oxygen dopants induces locally the\noff-diagonal (i.e., hopping integral) disorder. This disorder modulates the\nsuperexchange interaction resulting from a large-$U$ Hubbard model, which in\nturns changes the local pairing interaction. The microscopic self-consistent\ncalculations shows that the large gap regions are registered to the locations\nof dopants. Large gap regions exhibit small and broader coherence peaks. These\nresults are qualitatively consistent with recent STM observations on optimally\ndoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\\delta}$.",
        "category": "cond-mat"
    },
    {
        "text": "Measuring out quasi-local integrals of motion from entanglement: Quasi-local integrals of motion are a key concept underpinning the modern\nunderstanding of many-body localisation, an intriguing phenomenon in which\ninteractions and disorder come together. Despite the existence of several\nnumerical ways to compute them - and astoundingly in the light of the\nobservation that much of the phenomenology of many properties can be derived\nfrom them - it is not obvious how to directly measure aspects of them in real\nquantum simulations; in fact, the smoking gun of their experimental observation\nis arguably still missing. In this work, we propose a way to extract the\nreal-space properties of such quasi-local integrals of motion based on a\nspatially-resolved entanglement probe able to distinguish Anderson from\nmany-body localisation from non-equilibrium dynamics. We complement these\nfindings with a new rigorous entanglement bound and compute the relevant\nquantities using tensor networks. We demonstrate that the entanglement gives\nrise to a well-defined length scale that can be measured in experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Cumulative geometric frustration in physical assemblies: Geometric frustration arises whenever the constituents of a physical assembly\nlocally favor an arrangement that cannot be realized globally. Recently, such\nfrustrated assemblies were shown to exhibit filamentation, size limitation,\nlarge morphological variations and other exotic response properties. While\nthese unique characteristics can be shown to be a direct outcome of the\ngeometric frustration, some geometrically frustrated systems do not exhibit any\nof the above phenomena. In this work we exploit the intrinsic approach to\nprovide a framework for directly addressing the frustration in physical\nassemblies. The framework highlights the role of the compatibility conditions\nassociated with the intrinsic fields describing the physical assembly. We show\nthat the structure of the compatibility conditions determines the behavior of\nsmall assemblies, and in particular predicts their super-extensive energy\ngrowth exponent. We illustrate the use of this framework to several well known\nfrustrated assemblies.",
        "category": "cond-mat"
    },
    {
        "text": "Uniaxial extensional viscosity of semidilute DNA solutions: The extensional rheology of polymeric liquids has been extensively examined\nthrough experiments and theoretical predictions. However, a systematic study of\nthe extensional rheology of polymer solutions in the semidilute regime, in\nterms of examining the effects of concentration and molecular weight, has not\nbeen carried out so far. Prior studies of the shear rheology of semidilute\npolymer solutions have demonstrated that their behaviour is distinctively\ndifferent from that observed in the dilute and concentrated regimes. This\ndifference in behaviour is anticipated to be even more pronounced in\nextensional flows. In this work, the extensional rheology of linear,\ndouble-stranded DNA molecules, spanning an order of magnitude of molecular\nweights (25 to 289 kilobasepairs) and concentrations (0.03 to 0.3 mg/ml), has\nbeen investigated. DNA solutions are now used routinely as model polymeric\nsystems due to their near-perfect monodispersity. Measurements have been\ncarried out with a filament stretching rheometer since it is the most reliable\nmethod for obtaining an estimate of the elongational stress growth of a polymer\nsolution. Transient and steady-state uniaxial extensional viscosities of DNA\ndissolved in a solvent under excess salt conditions, with a high concentration\nof sucrose in order to achieve a sufficiently high solvent viscosity, have been\ndetermined in the semidilute regime at room temperature. The dependence of the\nsteady state uniaxial extensional viscosity on molecular weight, concentration\nand extension rate is measured with a view to determining if data collapse can\nbe observed with an appropriate choice of variables. Steady state shear\nviscosity measurements suggest that sucrose-DNA interactions might play a role\nin determining the observed rheological behaviour of semidilute DNA solutions\nwith sucrose as a component in the solvent.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetization curves of deposited finite spin chains: The characterization and manipulation of deposited magnetic clusters or\nmolecules on surfaces is a prerequisite for their future utilization. In recent\nyears techniques like spin-flip inelastic electron tunneling spectroscopy using\na scanning tunneling microscope proved to be very precise in determining e.g.\nexchange constants in deposited finite spin chains in the meV range. In this\narticle we tackle the problem numerically by investigating the transition from\nwhere a pure spin Hamiltonian is sufficient to the point where the interaction\nwith the surface significantly alters the magnetic properties. To this end we\nstudy the static, i.e. equilibrium impurity magnetization of antiferromagnetic\nchains for varying couplings to a conduction electron band of a metal\nsubstrate. We show under which circumstances the screening of a part of the\nsystem enables one to deduce molecular parameters of the remainder from level\ncrossings in an applied field.",
        "category": "cond-mat"
    },
    {
        "text": "Classical stochastic approach to quantum mechanics and quantum\n  thermodynamics: We derive the equations of quantum mechanics and quantum thermodynamics from\nthe assumption that a quantum system can be described by an underlying\nclassical system of particles. Each component $\\phi_j$ of the wave vector is\nunderstood as a stochastic complex variable whose real and imaginary parts are\nproportional to the coordinate and momentum associated to a degree of freedom\nof the underlying classical system. From the classical stochastic equations of\nmotion, we derive a general equation for the covariance matrix of the wave\nvector which turns out to be of the Lindblad type. When the noise changes only\nthe phase of $\\phi_j$, the Schr\\\"odinger and the quantum Liouville equation are\nobtained. The component $\\psi_j$ of the wave vector obeying the Schr\\\"odinger\nequation is related to stochastic wave vector by\n$|\\psi_j|^2=\\langle|\\phi_j|^2\\rangle$.",
        "category": "cond-mat"
    },
    {
        "text": "The electron many-body problem in graphene: We give a brief summary of the current status of the electron many-body\nproblem in graphene. We claim that graphene has intrinsic dielectric properties\nwhich should dress the interactions among the quasiparticles, and may explain\nwhy the observation of electron-electron renormalization effects has been so\nelusive in the recent experiments. We argue that the strength of Coulomb\ninteractions in graphene may be characterized by an effective fine structure\nconstant given by\n$\\alpha^{\\star}(\\mathbf{k},\\omega)\\equiv2.2/\\epsilon(\\mathbf{k},\\omega)$, where\n$\\epsilon(\\mathbf{k},\\omega)$ is the dynamical dielectric function. At long\nwavelengths, $\\alpha^{\\star}(\\mathbf{k},\\omega)$ appears to have its smallest\nvalue in the static regime, where $\\alpha^{\\star}(\\mathbf{k}\\to0,0)\\approx1/7$\naccording to recent inelastic x-ray measurements, and the largest value in the\noptical limit, where $\\alpha^{\\star}(0,\\omega)\\approx2.6$. We conclude that the\nstrength of Coulomb interactions in graphene is not universal, but depends\nhighly on the scale of the phenomenon of interest. We propose a prescription in\norder to reconcile different experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Off-diagonal Long-Range Order and Supersolidity in a Quantum Solid with\n  Vacancies: We consider a lattice of bosonic atoms, whose number N may be smaller than\nthe number of lattice sites M. We study the Hartree-Fock wave function built up\nfrom localized wave functios w(\\mathbf{r}) of single atoms, with nearest\nneighboring overlap. The zero-momentum particle number is expressed in terms of\npermanents of matrices. In one dimension, it is analytically calculated to be\n\\alpha*N(M-N+1)/M, with \\alpha=|\\int w(\\mathbf{r})d\\Omega|^2/[(1+2a)l], where a\nis the nearest-neighboring overlap, l is the lattice constant. \\alpha is of the\norder of 1. The result indicates that the condensate fraction is proportional\nto and of the same order of magnitude as that of the vacancy concentration,\nhence there is off-diagonal long-range order or Bose-Einstein condensation of\natoms when the number of vacancies M-N is a finite fraction of the number of\nthe lattice sites M.",
        "category": "cond-mat"
    },
    {
        "text": "Inverse design of two-dimensional structure by self-assembly of patchy\n  particles: We propose an optimisation method for the inverse structural design of\nself-assembly of anisotropic patchy particles. The anisotropic interaction can\nbe expressed by the spherical harmonics of the surface pattern on a patchy\nparticle, and thus arbitrary symmetry of the patch can be treated. The pairwise\ninteraction potential includes several to-be-optimised parameters, which are\nthe coefficient of each term in the spherical harmonics. We use the\noptimisation method based on the relative entropy approach and generate\nstructures by Brownian Dynamics simulations. Our method successfully estimates\nthe parameters in the potential for the target structures, such as square\nlattice, kagome lattice, and dodecagonal quasicrystal.",
        "category": "cond-mat"
    },
    {
        "text": "A comparative study of some models of incoherence at the mesoscopic\n  scale: The pre-existing literature on phenomena at the mesoscopic scale is concerned\namong other things with phase coherent transport. Phase coherent transport\ndominates at very low temperatures. With increase in temperature, as the system\nsize becomes comparable to the inelastic mean free path phase incoherence sets\nin. This incoherence further leads to dephasing, and as a consequence purely\nquantum effects in electron transport give way to classical macroscopic\nbehavior. In this work we consider two distinct phenomenological models of\nincoherent transport, the Coherent Absorption and Wave Attenuation models. We\nreveal some physical problems in the Coherent Absorption model as opposed to\nthe Wave Attenuation model. We also compare our proposed model with experiments\nin case of the much studied peak to valley ratios in resonant tunneling diodes,\nmagneto-conductance oscillations and Fano resonances in case of Aharonov-Bohm\nrings.",
        "category": "cond-mat"
    },
    {
        "text": "Coarse grained models of stripe forming systems: phase diagrams,\n  anomalies and scaling hypothesis: Two coarse-grained models which capture some universal characteristics of\nstripe forming systems are stud- ied. At high temperatures, the structure\nfactors of both models attain their maxima on a circle in reciprocal space, as\na consequence of generic isotropic competing interactions. Although this is\nknown to lead to some universal properties, we show that the phase diagrams\nhave important differences, which are a consequence of the particular k\ndependence of the fluctuation spectrum in each model. The phase diagrams are\ncomputed in a mean field approximation and also after inclusion of small\nfluctuations, which are shown to modify drastically the mean field behavior.\nObservables like the modulation length and magnetization profiles are computed\nfor the whole temperature range accessible to both models and some important\ndifferences in behavior are observed. A stripe compression modulus is computed,\nshowing an anomalous behavior with temperature as recently reported in related\nmodels. Also, a recently proposed scaling hypothesis for modulated systems is\ntested and found to be valid for both models studied.",
        "category": "cond-mat"
    },
    {
        "text": "Intentionally disordered superlattices with high dc conductance: We study disordered quantum-well-based semiconductor superlattices where the\ndisorder is intentional and short-range correlated. Such systems consist of\nquantum-wells of two different thicknesses randomly distributed along the\ngrowth direction, with the additional constraint that wells of one kind always\nappears in pairs. Imperfections due to interface roughness are considered by\nallowing the quantum-well thicknesses to fluctuate around their {\\em ideal}\nvalues. As particular examples, we consider wide-gap\n(GaAs-Ga$_{1-x}$Al$_{x}$As) and narrow-gap (InAs-GaSb) superlattices. We show\nthe existence of a band of extended states in perfect correlated disordered\nsuperlattices, giving rise to a strong enhancement of their finite-temperature\ndc conductance as compared to usual random ones whenever the Fermi level\nmatches this band. This feature is seen to survive even if interface roughness\nis taken into account. Our predictions can be used to demonstrate\nexperimentally that structural correlations inhibit the localization effects of\ndisorder, even in the presence of imperfections. This effect might be the basis\nof new, filter-like or other specific-purpose electronic devices.",
        "category": "cond-mat"
    },
    {
        "text": "Modulation Doping near Mott-Insulator Heterojunctions: We argue that interesting strongly correlated two-dimensional electron\nsystems can be created by modulation doping near a heterojunction between Mott\ninsulators. Because the dopant atoms are remote from the carrier system, the\nelectronic system will be weakly disordered. We argue that the competition\nbetween different ordered states can be engineered by choosing appropriate\nvalues for the dopant density and the setback distance of the doping layer. In\nparticular larger setback distances favor two-dimensional antiferromagnetism\nover ferromagnetism. We estimate some key properties of modulation-doped Mott\ninsulator heterojunctions by combining insights from Hartree-Fock-Theory and\nDynamical-Mean-Field-Theory descriptions and discuss potentially attractive\nmaterial combinations.",
        "category": "cond-mat"
    },
    {
        "text": "Field exposed water in a nanopore: liquid or vapour?: We study the behavior of ambient temperature water under the combined effects\nof nanoscale confinement and applied electric field. Using molecular\nsimulations we analyze the thermodynamic causes of field-induced expansion at\nsome, and contraction at other conditions. Repulsion among parallel water\ndipoles and mild weakening of interactions between partially aligned water\nmolecules prove sufficient to destabilize the aqueous liquid phase in isobaric\nsystems in which all water molecules are permanently exposed to a uniform\nelectric field. At the same time, simulations reveal comparatively weak\nfield-induced perturbations of water structure upheld by flexible hydrogen\nbonding. In open systems with fixed chemical potential, these perturbations do\nnot suffice to offset attraction of water into the field; additional water is\ntypically driven from unperturbed bulk phase to the field-exposed region. In\ncontrast to recent theoretical predictions in the literature, our analysis and\nsimulations confirm that classical electrostriction characterizes usual\nelectrowetting behavior in nanoscale channels and nanoporous materials.",
        "category": "cond-mat"
    },
    {
        "text": "Anomalous thermal Hall effect in the topological antiferromagnetic state: The anomalous Hall effect (AHE), a Hall signal occurring without an external\nmagnetic field, is one of the most significant phenomena. However,\nunderstanding the AHE mechanism has been challenging and largely restricted to\nferromagnetic metals. Here, we investigate the recently discovered AHE in the\nchiral antiferromagnet Mn3Sn by measuring a thermal analog of the AHE, known as\nan anomalous thermal Hall effect (ATHE). The amplitude of the ATHE scales with\nthe anomalous Hall conductivity of Mn3Sn over a wide temperature range,\ndemonstrating that the AHE of Mn3Sn arises from a dissipationless intrinsic\nmechanism associated with the Berry curvature. Moreover, we find that the\ndissipationless AHE is significantly stabilized by shifting the Fermi level\ntoward the magnetic Weyl points. Thus, in Mn3Sn, the Berry curvature emerging\nfrom the proposed magnetic Weyl fermion state is a key factor for the observed\nAHE and ATHE.",
        "category": "cond-mat"
    },
    {
        "text": "Spin exchange in quantum rings and wires in the Wigner-crystal limit: We present a controlled method for computing the exchange coupling in\nstrongly correlated one-dimensional electron systems. It is based on the\nasymptotically exact relation between the exchange constant and the\npair-correlation function of spinless electrons. Explicit results are obtained\nfor thin quantum rings with realistic Coulomb interactions, by calculating this\nfunction via a many-body instanton approach.",
        "category": "cond-mat"
    },
    {
        "text": "Negative and Positive Magnetoresistance in Bilayer Graphene: Effects of\n  Weak Localization and Charge Inhomogeneity: We report measurements of magnetoresistance in bilayer graphene as a function\nof gate voltage (carrier density) and temperature. We examine multiple\ncontributions to the magnetoresistance, including those of weak localization\n(WL), universal conductance fluctuations (UCF), and inhomogeneous charge\ntransport. A clear WL signal is evident at all measured gate voltages (in the\nhole doped regime) and temperature ranges (from 0.25 K to 4.3 K), and the phase\ncoherence length extracted from WL data does not saturate at low temperatures.\nThe WL data is fit to demonstrate that electron-electron Nyquist scattering is\nthe major source of phase decoherence. A decrease in UCF amplitude with\nincreasing gate voltage and temperature is shown to be consistent with a\ncorresponding decrease in the phase coherence length. In addition, a weak\npositive magnetoresistance at higher magnetic fields is observed, and\nattributed to inhomogeneous charge transport.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of chirality imbalance on Hall transport of PrRhC$_2$: Much has been learned about the topological transport in real materials. We\ninvestigate the interplay between magnetism and topology in the\nmagneto-transport of PrRhC$_2$. The four-fold degeneracy reduces to two-fold\nfollowed by non-degenerate Weyl nodes when the orientation of the magnetic\nquantization axis is changed from easy axis to body-diagonal through\nface-diagonal. This engenders chirality imbalance between positive and negative\nchirality Weyl nodes around the Fermi energy. We observe a significant\nenhancement in the chiral anomaly mediated response such as planar Hall\nconductivity and longitudinal magneto-conductivity, due to the emergence of\nchirality imbalance upon orienting the magnetic quantization axis to\nbody-diagonal. The angular variations of the above quantities for different\nmagnetic quantization axis clearly refer to the typical signature of planar\nHall effect in Weyl semimetals. We further investigate the profiles of\nanomalous Hall conductivities as a function of Fermi energy to explore the\neffects of symmetries as well as chirality imbalance on Berry curvature.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic coherent tunnel junctions with periodic grating barrier: A new spintronic theory has been developed for the magnetic tunnel junction\n(MTJ) with single-crystal barrier. The barrier will be treated as a diffraction\ngrating with intralayer periodicity, the diffracted waves of tunneling\nelectrons thus contain strong coherence, both in charge and especially in spin.\nThe theory can answer the two basic problems present in MgO-based MTJs: (1) Why\ndoes the tunneling magnetoresistance (TMR) oscillate with the barrier\nthickness? (2) Why is the TMR still far away from infinity when the two\nelectrodes are both half-metallic? Other principal features of TMR can also be\nexplained and reproduced by the present work. It also provides possible ways to\nmodulate the oscillation of TMR, and to enhance TMR so that it can tend to\ninfinity. Within the theory, the barrier, as a periodic diffraction grating,\ncan get rid of the confinement in width, it can vary from nanoscale to\nmicroscale. Based on those results, a future-generation MTJ is proposed where\nthe three pieces can be fabricated separately and then assembled together, it\nis especially appropriate for the layered materials, e.g., MoS2 and graphite,\nand most feasible for industries.",
        "category": "cond-mat"
    },
    {
        "text": "Transient dynamics of strongly coupled spin vortex pairs: effects of\n  anharmonicity and resonant excitation on inertial switching: Spin vortices in magnetic nanopillars are used as GHz oscillators, with\nfrequency however essentially fixed in fabrication. We demonstrate a model\nsystem of a two-vortex nanopillar, in which the resonance frequency can be\nchanged by an order of magnitude, without using high dc magnetic fields. The\neffect is due to switching between the two stable states of the vortex pair,\nwhich we show can be done with low-amplitude fields of sub-ns duration. We\ndetail the relevant vortex-core dynamics and explain how field anharmonicity\nand phase control can be used to enhance the performance.",
        "category": "cond-mat"
    },
    {
        "text": "Cooper Instability in the Occupation Dependent Hopping Hamiltonians: A generic Hamiltonian, which incorporates the effect of the orbital\ncontraction on the hopping amplitude between the nearest sites, is studied both\nanalytically at the weak coupling limit and numerically at the intermediate and\nstrong coupling regimes for finite atomic cluster. The effect of the orbital\ncontraction due to hole localization at atomic sites is specified with two\ncoupling parameters V and W (multiplicative and additive contraction terms).\nThe singularity of the vertex part of the two-particle Green's function\ndetermines the critical temperature Tc and the relaxation rate Gamma(T) of the\norder parameter at temperature above Tc. Unlike in conventional BCS\nsuperconductors, Gamma has a non-zero imaginary part which may influence the\nfluctuation conductivity of superconductor above Tc. We compute the ground\nstate energy as a function of the particle number and magnetic flux through the\ncluster, and show the existence of the parity gap Delta appearing at the range\nof system parameters consistent with the appearance of Cooper instability.\nNumeric calculation of the Hubbard model (with U>0) at arbitrary occupation\ndoes not show any sign of superconductivity in small cluster.",
        "category": "cond-mat"
    },
    {
        "text": "Composite fermion dynamics in half-filled Landau levels of graphene: We report on exact-diagonalization studies of correlated many-electron states\nin the half-filled Landau levels of graphene, including pseudospin (valley)\ndegeneracy. We demonstrate that the polarized Fermi sea of non-interacting\ncomposite fermions remains stable against a pairing transition in the lowest\ntwo Landau levels. However, it undergoes spontaneous depolarization, which is\nunprotected owing to the lack of single-particle pseudospin splitting. These\nresults suggest the absence of the Pfaffian phase in graphene.",
        "category": "cond-mat"
    },
    {
        "text": "Traveling waves in reaction-diffusion system: A new asymptotic method is presented for the analysis of the traveling waves\nin the one-dimensional reaction-diffusion system with the diffusion with a\nfinite velocity and Kolmogorov-Petrovskii-Piskunov kinetics. The analysis makes\nuse of the path-integral approach, scaling procedure and the singular\nperturbation techniques involving the large deviations theory for the Poisson\nrandom walk. The exact formula for the position and speed of reaction front is\nderived. It is found that the reaction front dynamics is formally associated\nwith the relativistic Hamiltonian/Lagrangian mechanics.",
        "category": "cond-mat"
    },
    {
        "text": "Temperature- and Force-Induced beta-Sheet Unfolding in an Exactly\n  Solvable Model: The stability of a $\\beta$-sheeted conformation and its transition into a\nrandom coil are studied with a 2D lattice biopolymer model. At low temperature\nand low external force, the polymer folds back and forth on itself and forms a\n$\\beta$-sheet. Our analytical calculation and Monte Carlo simulation reveal\nthat a co-operative $\\beta$-sheet--random coil transition takes places when the\ntemperature or force is increased, with a dramatic decrease in the contact\nnumber. These predictions are in good agreement with experiments on titin\nprotein. This transition is not a real phase-transition, indicating that\nbackbone hydrogen-bonding alone is unable to stabilize a distinct $\\beta$-sheet\nphase.",
        "category": "cond-mat"
    },
    {
        "text": "Landau Levels in Strained Optical Lattices: We propose a hexagonal optical lattice system with spatial variations in the\nhopping matrix elements. Just like in the valley Hall effect in strained\nGraphene, for atoms near the Dirac points the variations in the hopping matrix\nelements can be described by a pseudo-magnetic field and result in the\nformation of Landau levels. We show that the pseudo-magnetic field leads to\nmeasurable experimental signatures in momentum resolved Bragg spectroscopy,\nBloch oscillations, cyclotron motion, and quantization of in-situ densities.\nOur proposal can be realized by a slight modification of existing experiments.\nIn contrast to previous methods, pseudo-magnetic fields are realized in a\ncompletely static system avoiding common heating effects and therefore opening\nthe door to studying interaction effects in Landau levels with cold atoms.",
        "category": "cond-mat"
    },
    {
        "text": "Quasi-one-dimensional charge density wave in electromagnetic field\n  arbitrarily oriented to conducting chains: generalized Frohlich relations: We derive equations for the collective CDW-current transverse conducting\nchains in a quasi-one-dimensional CDW-conductor. Generalized Frohlich relations\nbetween the transverse currents and phase gradients are due to the polarization\ncorrections to the 1+1 chiral anomaly Lagrangean. The CDW Hall constant is\ncalculated.",
        "category": "cond-mat"
    },
    {
        "text": "Surface Engineering for Phase Change Heat Transfer: A Review: Among numerous challenges to meet the rising global energy demand in a\nsustainable manner, improving phase change heat transfer has been at the\nforefront of engineering research for decades. The high heat transfer rates\nassociated with phase change heat transfer are essential to energy and industry\napplications; but phase change is also inherently associated with poor\nthermodynamic efficiencies at low heat flux, and violent instabilities at high\nheat flux. Engineers have tried since the 1930's to fabricate solid surfaces\nthat improve phase change heat transfer. The development of micro and\nnanotechnologies has made feasible the high-resolution control of surface\ntexture and chemistry over length scales ranging from molecular levels to\ncentimeters. This paper reviews the fabrication techniques available for\nmetallic and silicon-based surfaces, considering sintered and polymeric\ncoatings. The influence of such surfaces in multiphase processes of high\npractical interest, e.g., boiling, condensation, freezing, and the associated\nphysical phenomena are reviewed. The case is made that while engineers are in\nprinciple able to manufacture surfaces with optimum nucleation or thermofluid\ntransport characteristics, more theoretical and experimental efforts are needed\nto guide the design and cost-effective fabrication of surfaces that not only\nsatisfy the existing technological needs, but also catalyze new discoveries.",
        "category": "cond-mat"
    },
    {
        "text": "Shear Banding and Spatiotemporal Oscillations in Vortex Matter in\n  Nanostructured Superconductors: We propose a simple nanostructured pinning array geometry where a rich\nvariety of complex vortex shear banding phenomena can be realized. A single row\nof pinning sites is removed from a square pinning array. Shear banding effects\narise when vortex motion in the pin-free channel nucleates motion of vortices\nin the surrounding pinned regions, creating discrete steps in the vortex\nvelocity profile away from the channel. Near the global depinning transition,\nthe width of the band of moving vortices undergoes oscillations or fluctuations\nthat can span the entire system. We use simulations to show that these effects\nshould be observable in the transport properties of the system. Similar large\noscillations and shear banding effects are known to occur for sheared complex\nfluids in which different dynamical phases coexist.",
        "category": "cond-mat"
    },
    {
        "text": "Angle-dependent ultrasonic transmission through plates with\n  subwavelength hole arrays: We study sound transmission in perforated plates as a function of incident\nangle and conclude that it holds distinctive properties that make it unique and\nessentially different from optical transmission through perforated metallic\nplates. More precisely, we conclude the following: (a) similar to its optical\ncounterpart, acoustic transmission minima respond to Wood anomalies in which\nthe periodicity plays a central role; (b) in contrast to both the optical case\nand the acoustical case with slits, homogeneous-plate modes (Lamb and\nScholte-Stoneley modes) are strongly coupled to lattice and Fabry-P\\'erot\nresonances. This gives rise to unique transmission behavior, thus opening new\nperspectives for exotic wave phenomena.",
        "category": "cond-mat"
    },
    {
        "text": "Analysis of the valence band photoemission spectrum of\n  Sr$_2$CuO$_2$Cl$_2$ along the high-symmetry directions: Band structure calculations have been used to identify the different bands\ncontributing to the polarisation-dependent photoemission spectra of the undoped\nmodel cuprate Sr$_2$CuO$_2$Cl$_2$ at the high-symmetry points of the CuO$_2$\nplane $\\Gamma$, $(\\pi/a,0)$ and $(\\pi/a,\\pi/a)$ and along the high-symmetry\ndirections $\\Gamma - (\\pi/a,\\pi/a)$ and $\\Gamma - (\\pi/a,0)$. Results from\ncalculations within the local density approximation (LDA) have been compared\nwith calculations taking into account the strong electron correlations by\nLDA+U, with the result that the experimental order of energy levels at the\nhigh-symmetry points is better described by the LDA+U calculation than by the\nsimple LDA. All the main peaks in the photoemission spectra at the high\nsymmetry points could be assigned to different Cu 3$d$ and O 2$p$ orbitals\nwhich we have classified according to their point symmetries. The dispersions\nalong the high-symmetry directions were compared with an 11-band tight-binding\nmodel which was fitted both to the LDA+U band structure calculation and the\nangle-resolved photoemission data. The mean field treatment successfully\ndescribes the oxygen derived bands but shows discrepancies for the copper ones.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of charged excitons in hole-doped carbon nanotubes using\n  photoluminescence and absorption spectroscopy: We report the first observation of trions (charged excitons), three-particle\nbound states consisting of one electron and two holes, in hole-doped carbon\nnanotubes at room temperature. When p-type dopants are added to carbon nanotube\nsolutions, the photoluminescence and absorption peaks of the trions appear far\nbelow the E11 bright exciton peak, regardless of the dopant species. The\nunexpectedly large energy separation between the bright excitons and the trions\nis attributed to the strong electron-hole exchange interaction in carbon\nnanotubes.",
        "category": "cond-mat"
    },
    {
        "text": "X-ray cross-correlation analysis of disordered systems: potentials and\n  limitations: Angular x-ray cross-correlation analysis (XCCA) is an approach to study the\nstructure of disordered systems using the results of x-ray scattering\nexperiments. In this paper we summarize recent theoretical developments related\nto the Fourier analysis of the cross-correlation functions. Results of our\nsimulations demonstrate the application of XCCA to two- and three-dimensional\n(2D and 3D) disordered systems of particles. We show that the structure of a\nsingle particle can be recovered using x-ray data collected from a 2D\ndisordered system of identical particles. We also demonstrate that valuable\nstructural information about the local structure of 3D systems, inaccessible\nfrom a standard small-angle x-ray scattering experiment, can be resolved using\nXCCA.",
        "category": "cond-mat"
    },
    {
        "text": "Some words on the \"phase transitions\" in magnetic mesoscopic system: \"Phase transitions\" between quantum and classical behaviour in large spin\nmagnetic systems discused.",
        "category": "cond-mat"
    },
    {
        "text": "Pairs of Bloch electrons and magnetic translation groups: A product of irreducible representations of magnetic translation group is\nconsidered. It leads to irreducible representations which were previously\nrejected as nonphysical. A very simple example indicates a possible application\nof these representations. In particular, they are important in descriptions of\npairs of electrons in a magnetic field and a periodic potential. The\nperiodicity of some properties with respect to the charge of a particle is\nbriefly discussed.",
        "category": "cond-mat"
    },
    {
        "text": "A Simple Method to Make the Wang-Landau Sampling Converge: We show that a histogram maintained throughout the Wang-Landau (WL) sampling\nfor the energy entries visited during the simulation could be used to make the\nsimulated density of states (DOS) converge. The method is easy to be\nimplemented to the WL sampling with no extra computational cost and bears the\nadvantages of both the WL method and the multicanonical method.",
        "category": "cond-mat"
    },
    {
        "text": "Replica Cluster Variational Method: the Replica Symmetric solution for\n  the 2D random bond Ising model: We present and solve the Replica Symmetric equations in the context of the\nReplica Cluster Variational Method for the 2D random bond Ising model\n(including the 2D Edwards-Anderson spin glass model). First we solve a\nlinearized version of these equations to obtain the phase diagrams of the model\non the square and triangular lattices. In both cases the spin-glass transition\ntemperatures and the tricritical point estimations improve largely over the\nBethe predictions. Moreover, we show that this phase diagram is consistent with\nthe behavior of inference algorithms on single instances of the problem.\nFinally, we present a method to consistently find approximate solutions to the\nequations in the glassy phase. The method is applied to the triangular lattice\ndown to T=0, also in the presence of an external field.",
        "category": "cond-mat"
    },
    {
        "text": "Lack of an equation of state for the nonequilibrium chemical potential\n  of gases of active particles in contact: We discuss the notion of nonequilibrium chemical potential in gases of\nnon-interacting active particles filling two compartments separated by a\npotential energy barrier. Different types of active particles are considered:\nrun-and-tumble particles, active Brownian particles, and active Brownian\nparticles with a stochastic reorientation along an external field. After\nrecalling some analytical results for run-and-rumble particles in one\ndimension, we focus on the two-dimensional case and obtain a perturbative\nexpression of the density profile in the limit of a fast reorientation\ndynamics, for the three models of active particles mentioned above. Computing\nthe chemical potentials of the non-equilibrium systems in contact from the\nknowledge of the stationary probability distribution of the whole system\n---which agrees with a recently proposed general definition of the chemical\npotential in non-equilibrium systems in contact--- we generically find that the\nchemical potential lacks an equation of state, in the sense that it depends on\nthe detailed shape of the potential energy barrier separating the compartments\nand not only on bulk properties, at odds with equilibrium. This situation is\nreminiscent of the properties of the mechanical pressure in active systems. We\nalso argue that the Maxwell relation is no longer valid and cannot be used to\ninfer the nonequilibrium chemical potential from the knowledge of the\nmechanical pressure.",
        "category": "cond-mat"
    },
    {
        "text": "Universality class of Ising critical states with long-range losses: We show that spatial resolved dissipation can act on $d$-dimensional spin\nsystems in the Ising universality class by qualitatively modifying the nature\nof their critical points. We consider power-law decaying spin losses with a\nLindbladian spectrum closing at small momenta as $\\propto q^\\alpha$, with\n$\\alpha$ a positive tunable exponent directly related to the power-law decay of\nthe spatial profile of losses at long distances, $1/r^{(\\alpha+d)}$. This\nyields a class of soft modes asymptotically decoupled from dissipation at small\nmomenta, which are responsible for the emergence of a critical scaling regime\nascribable to the non-unitary counterpart of the universality class of\nlong-range interacting Ising models. For $\\alpha<1$ we find a non-equilibrium\ncritical point ruled by a dynamical field theory described by a Langevin model\nwith coexisting inertial ($\\sim {\\partial^2_t}$) and frictional ($\\sim\n{\\partial_t}$) kinetic coefficients, and driven by a gapless Markovian noise\nwith variance $\\propto q^\\alpha$ at small momenta. This effective field theory\nis beyond the Halperin-Hohenberg description of dynamical criticality, and its\ncritical exponents differ from their unitary long-range counterparts. Our work\nlays out perspectives for a revision of universality in driven-open systems by\nemploying dark states taylored by programmable dissipation.",
        "category": "cond-mat"
    },
    {
        "text": "Correspondence between winding numbers and skin modes in non-hermitian\n  systems: We establish exact relations between the winding of \"energy\" (eigenvalue of\nHamiltonian) on the complex plane as momentum traverses the Brillouin zone with\nperiodic boundary condition, and the presence of \"skin modes\" with open\nboundary condition in non-hermitian systems. We show that the nonzero winding\nwith respect to any complex reference energy leads to the presence of skin\nmodes, and vice versa. We also show that both the nonzero winding and the\npresence of skin modes share the common physical origin that is the\nnon-vanishing current through the system.",
        "category": "cond-mat"
    },
    {
        "text": "Coexistence of Superconductivity and Antiferromagnetism in the Hubbard\n  model for cuprates: Antiferromagnetism and $d$-wave superconductivity are the most important\ncompeting ground-state phases of cuprate superconductors. Using cellular\ndynamical mean-field theory (CDMFT) for the Hubbard model, we revisit the\nquestion of the coexistence and competition of these phases in the one-band\nHubbard model with realistic band parameters and interaction strengths. With an\nexact diagonalization solver, we improve on previous works with a more complete\nbath parametrization which is carefully chosen to grant the maximal possible\nfreedom to the hybridization function for a given number of bath orbitals.\nCompared with previous incomplete parametrizations, this general bath\nparametrization shows that the range of microscopic coexistence of\nsuperconductivity and antiferromagnetism is reduced for band parameters for\nNCCO, and confined to electron-doping with parameters relevant for YBCO.",
        "category": "cond-mat"
    },
    {
        "text": "A new field-theoretical formulation for the motion of an electron in a\n  quenched disorder potential: Following a proposal by Aronov and Ioselevich, we express the Green functions\n(GF) of a noninteracting disordered Fermi system as a functional integral on a\nreal time/frequency lattice. The normalizing denominator of this functional\nintegral is equal to unity, because of identities satisfied by the GF. The GF\ncan then be simply averaged with respect to the random disorder potential. We\ndescribe the fermionic fields not belonging to the external frequency by means\nof a bosonic auxiliary field g. The Hubbard-Stratonovich field Q is introduced\nonly with respect to the fermionic fields for the external frequency.",
        "category": "cond-mat"
    },
    {
        "text": "Theoretical analysis of anisotropic upper critical field of\n  superconductivity in nodal-line semimetals: We study the properties of the upper critical field of superconductivity in\nnodal-line semimetals in a continuous model, which has a nodal-line on the\n$k_{z} = 0$ plane. Using the semiclassical Green's function method, we\ncalculate the upper critical field for the two limiting cases: the dirty limit\nwith many impurities and the clean limit with few impurities. The results show\nthe large anisotropy of the magnitude of the upper critical field and the\nunusual temperature dependence. The obtained results are compared with recent\nexperimental data of PbTaSe$_{2}$.",
        "category": "cond-mat"
    },
    {
        "text": "Molecular dynamics simulation of the fragile glass former\n  ortho-terphenyl: a flexible molecule model: We present a realistic model of the fragile glass former orthoterphenyl and\nthe results of extensive molecular dynamics simulations in which we\ninvestigated its basic static and dynamic properties. In this model the\ninternal molecular interactions between the three rigid phenyl rings are\ndescribed by a set of force constants, including harmonic and anharmonic terms;\nthe interactions among different molecules are described by Lennard-Jones\nsite-site potentials. Self-diffusion properties are discussed in detail\ntogether with the temperature and momentum dependencies of the\nself-intermediate scattering function. The simulation data are compared with\nexisting experimental results and with the main predictions of the Mode\nCoupling Theory.",
        "category": "cond-mat"
    },
    {
        "text": "Bose-Einstein Condensation on Curved Manifolds: Here we describe a weakly interacting Bose gas on a curved manifold, which is\nembedded in the three-dimensional Euclidean space.~To this end we start by\nconsidering a harmonic trap in the normal direction of the manifold, which\nconfines the three-dimensional Bose gas in the vicinity of its\nsurface.~Following the notion of dimensional reduction as outlined in\n[L.~Salasnich et al., Phys.~Rev.~A {\\bf 65}, 043614 (2002)], we assume a large\nenough trap frequency so that the normal degree of freedom of the condensate\nwave function can be approximately integrated out. In this way we obtain an\neffective condensate wave function on the quasi-two-dimensional surface of the\ncurved manifold, where the thickness of the cloud is determined\nself-consistently. For the particular case when the manifold is a sphere, our\nequilibrium results show how the chemical potential and the thickness of the\ncloud increase with the interaction strength.~Furthermore, we determine within\na linear stability analysis the low-lying collective excitations together with\ntheir eigenfrequencies, which turn out to reveal an instability for attractive\ninteractions.",
        "category": "cond-mat"
    },
    {
        "text": "Fermi level dependent charge-to-spin current conversion by Dirac surface\n  state of topological insulators: The spin-momentum locking at the Dirac surface state of a topological\ninsulator (TI) offers a distinct possibility of a highly efficient\ncharge-to-spin current (C-S) conversion compared with spin Hall effects in\nconventional paramagnetic metals. For the development of TI-based spin current\ndevices, it is essential to evaluate its conversion efficiency quantitatively\nas a function of the Fermi level EF position. Here we exemplify a coefficient\nof qICS to characterize the interface C-S conversion effect by using spin\ntorque ferromagnetic resonance (ST-FMR) for (Bi1-xSbx)2Te3 thin films whose EF\nis tuned across the band gap. In bulk insulating conditions, interface C-S\nconversion effect via Dirac surface state is evaluated as nearly constant large\nvalues of qICS, reflecting that the qICS is inversely proportional to the Fermi\nvelocity vF that is almost constant. However, when EF traverses through the\nDirac point, the qICS is remarkably suppressed possibly due to the degeneracy\nof surface spins or instability of helical spin structure. These results\ndemonstrate that the fine tuning of the EF in TI based heterostructures is\ncritical to maximizing the efficiency using the spin-momentum locking\nmechanism.",
        "category": "cond-mat"
    },
    {
        "text": "Pairing mechanism of high-temperature superconductivity: Experimental\n  constraints: Developing a theory of high-temperature superconductivity in copper oxides is\none of the outstanding problems in physics. It is a challenge that has defeated\ntheoretical physicists for more than twenty years. Attempts to understand this\nproblem are hindered by the subtle interplay among a few mechanisms and the\npresence of several nearly degenerate and competing phases in these systems.\nHere we present some crucial experiments that place essential constraints on\nthe pairing mechanism of high-temperature superconductivity. The observed\nunconventional oxygenisotope effects in cuprates have clearly shown strong\nelectron-phonon interactions and the existence of polarons and/or bipolarons.\nAngle-resolved photoemission and tunneling spectra have provided direct\nevidence for strong coupling to multiple-phonon modes. In contrast, these\nspectra do not show strong coupling features expected for magnetic resonance\nmodes. Angle-resolved photoemission spectra and the oxygen-isotope effect on\nthe antiferromagnetic exchange energy J in undoped parent compounds\nconsistently show that the polaron binding energy is about 2 eV, which is over\none order of magnitude larger than J = 0.14 eV. The normal-state\nspin-susceptibility data of holedoped cuprates indicate that intersite\nbipolarons are the dominant charge carriers in the underdoped region while the\ncomponent of Fermi-liquid-like polarons is dominant in the overdoped region.\nAll the experiments to test the gap or order-parameter symmetry consistently\ndemonstrate that the intrinsic gap (pairing) symmetry for the Fermi-liquid-like\ncomponent is anisotropic s-wave and the order-parameter symmetry of the\nBose-Einstein condensation of bipolarons is d-wave.",
        "category": "cond-mat"
    },
    {
        "text": "Adiabatic quantum pumping of chiral Majorana fermions: We investigate adiabatic quantum pumping of chiral Majorana states in a\nsystem composed of two Mach--Zehnder type interferometers coupled via a quantum\npoint contact. The pumped current is generated by periodic modulation of the\nphases accumulated by traveling around each interferometer. Using scattering\nmatrix formalism we show that the pumped current reveals a definite signature\nof the chiral nature of the Majorana states involved in transport in this\ngeometry. Furthermore, by tuning the coupling between the two interferometers\nthe pump can operate in a regime where finite pumped current and zero\ntwo-terminal conductance is expected.",
        "category": "cond-mat"
    },
    {
        "text": "Impact of charge distribution of soft layers on transient electroosmotic\n  flow of Maxwell fluids in soft nanochannels: We theoretically study transient electroosmotic flow of general Maxwell\nfluids through polyelectrolyte grafted nanochannel with a layered distribution\nof charges.\n  By applying the method of Laplace transform, we semi-analytically obtain\ntransient electroosmotic flow from Cauchy momentum equation and Maxwell\nconstitutive equation.\n  For nanochannels grafted with polyelectrolyte layers having different layered\ndistribution of charges, we study the influence of dimensionless relaxation\ntime, dimensionless polyelectrolyte layer thickness and dimensionless drag\ncoefficient on transient electroosmotic flow.\n  We present the results for some particular cases. Firstly, we unravel that\nfor the case of polyzwitterionic brush that the sum of positive and negative\nstructural charges is zero, total electroosmotic flow is non-zero. In\nparticular, depending on charge distribution within end part of polyelectrolyte\nlayers, the direction of electroosmotic flow can be reversed critically.\nSecondly, in order to quantitatively evaluate a reversal of electroosmotic flow\nfor two polyelectrolyte layers of opposite signs, we introduce a critical\nnumber ks as the ratio between layered charge densities of two polyelectrolyte\nlayers. Increasing ks allows electroosmotic flow to be reversed easily.\n  We verify that adjusting charge distributions of the layer can control\nintentionally the direction of the flows as well as strength of electroosmotic\nflow.",
        "category": "cond-mat"
    },
    {
        "text": "Electron-phonon interaction in the dynamics of trap filling in quantum\n  dots: We analyze theoretically the effects of electron-phonon interaction in the\ndynamics of an electron that can be trapped to a localized state and detrapped\nto an extended band state of a small quantum dot (QD) using a simple model\nsystem. In spite of its simplicity the time dependent model has no analytical\nsolution but a numerically exact one can be found producing a rich dynamics.\nThe electronic motion is quasi-periodic in time, with oscillations around a\nmean value that are basic characteristics of the weak and strong coupling\nregimes of electron-phonon interaction and set the time scales of the system.\nUsing values of the parameters appropriate for defects in semiconductor QDs, we\nfind these time scales to range typically from tenths of picoseconds to a few\npicoseconds. The values of the time averaged trap occupancy strongly depend on\nthe the strength of the electron-phonon interaction and can be as large as\n40$\\%$ when the coupling is most efficient, independently of other parameters.\nAn interesting result of the present work is the formation of resonances at\nspecific values of the electron-phonon coupling parameter that only exist when\nseveral levels are allowed to coherently cooperate in the filling of the trap.\nThey are characterized by a trap occupancy that is a periodic function of time\nwith large amplitude and period picturing an electron that is periodically\ntrapped and detrapped. We conclude that the formation of these resonances is a\nrobust consequence of electron-phonon interaction in small systems.\nElectron-phonon interaction is an efficient mechanism that can provide ca.\n50$\\%$ filling of a deep trap state on a subpicoseconds to picoseconds time\nscale, much faster than radiative decay occurring in time scales of tens of\npicoseconds to nanoseconds, while the occupancy of this state will be smaller\nthan ca. 1$\\%$ in the absence of electron-phonon coupling.",
        "category": "cond-mat"
    },
    {
        "text": "Voltage-controlled transmission in a dielectric slab doped with the\n  quantum dot molecules: Transmission and reflection of an electromagnetic pulse through a dielectric\nslab doped with the quantum dot molecules is investigated. It is shown that the\ntransmitted and reflected pulses depend on the inter-dot tunneling effect and\ncan be controlled by applying a gate voltage.",
        "category": "cond-mat"
    },
    {
        "text": "Spontaneous Rotation of Ferrimagnetism Driven by Antiferromagnetic Spin\n  Canting: Spin-reorientation phase transitions that involve the rotation of a\ncrystal$'$s magnetization have been well characterized in distorted-perovskite\noxides such as the orthoferrites. In these systems spin reorientation occurs\ndue to competing rare-earth and transition metal anisotropies coupled via\n$f$-$d$ exchange. Here, we demonstrate an alternative paradigm for spin\nreorientation in distorted perovskites. We show that the\n$R_2\\mathrm{CuMnMn_4O_{12}}$ (R = Y or Dy) triple A-site columnar-ordered\nquadruple perovskites have three ordered magnetic phases and up to two\nspin-reorientation phase transitions. Unlike the spin-reorientation phenomena\nin other distorted perovskites, these transitions are independent of rare-earth\nmagnetism, but are instead driven by an instability towards antiferromagnetic\nspin canting likely originating in frustrated Heisenberg exchange interactions,\nand the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.",
        "category": "cond-mat"
    },
    {
        "text": "Collective excitation of electric dipole on molecular dimer in organic\n  dimer-Mott insulator: The terahertz (THz) response in 10-100 cm^-1 was investigated in an organic\ndimer-Mott (DM) insulator kappa-(ET)_2Cu_2(CN)_3 that exhibits a relaxor-like\ndielectric anomaly. 30 cm^-1 band in the optical conductivity was attributable\nto collective excitation of the intra-dimer electric dipoles which are formed\nby an electron correlation. We succeeded in observing photoinduced enhancement\nof this 30 cm^-1 band, reflecting the growth of the electric dipole cluster in\nthe DM phase. Such optical responses in kappa-(ET)_2Cu_2(CN)_3 reflect\ninstability near the boundary between the DM-ferroelectric charge ordered\nphases.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of sodium pyrophosphate and understanding microstructure of\n  aqueous LAPONITE(R) dispersion using dissolution study: We investigate physical origin of ergodicity breaking in an aqueous colloidal\ndispersion of synthetic hectorite clay, LAPONITE(R), by performing dissolution\nand rheological experiments with monovalent salt and tetrasodium pyrophosphate\nsolution. We also study the effect of interface, nitrogen and paraffin oil on\nthe same. Dissolution experiments carried out for dispersions with both the\ninterfaces show similar results. However, for samples with nitrogen interface,\nall the effects are observed to get expedited in time compared to paraffin oil\ninterface. When kept in contact with water, 1.5 wt. % and 2.8 wt. % colloidal\ndispersion at pH 10 swell at small ages, while do not swell at large ages. The\nsolution of tetrasodium pyrophosphate, interestingly, dissolves the entire\ncolloidal dispersion samples with pH 10 irrespective of the clay concentration.\nExperiments carried out on colloidal dispersions prepared in water having pH 13\ndemonstrate no effect of water as well as sodium pyrophosphate solution on the\nsame suggesting a possibility of the presence of negative charge on edge at\nthat pH. We believe that all the behaviors observed for samples at pH 10 can be\nexplained by an attractive gel microstructure formed by edge-to-face contact.\nFurthermore, the absence of swelling in old colloidal dispersion at pH 10 and\ndissolution of the same by sodium pyrophosphate solution cannot be explained by\nmerely repulsive interactions. This behavior suggests that attractive\ninteractions play an important role in causing ergodicity breaking in the\ncolloidal dispersions at pH 10 at all the ages irrespective of the clay\nconcentration. We substantiate the presence of fractal network structure formed\nby interparticle edge-face association using rheological tools and cryo-TEM\nimaging. We also conduct a comprehensive study of the effect of sodium\npyrophosphate in the sol-gel transition of LAPONITE(R) dispersion.",
        "category": "cond-mat"
    },
    {
        "text": "Mode-Locking in Quantum-Hall-Effect Point Contacts: We study the effect of an ac drive on the current-voltage (I-V)\ncharacteristics of a tunnel junction between two fractional Quantum Hall fluids\nat filling $\\nu ^{-1}$ an odd integer. Within the chiral Luttinger liquid model\nof edge states, the point contact dynamics is described by a driven damped\nquantum mechanical pendulum. In a semi-classical limit which ignores electron\ntunnelling, this model exhibits mode-locking, which corresponds to current\nplateaus in the I-V curve at integer multiples of $I= e\\omega /2\\pi$, with\n$\\omega$ the ac drive angular frequency. By analyzing the full quantum model at\nnon-zero $\\nu$ using perturbative and exact methods, we study the effect of\nquantum fluctuation on the mode-locked plateaus. For $\\nu=1$ quantum\nfluctuations smear completely the plateaus, leaving no trace of the ac drive.\nFor $\\nu \\ge 1/2$ smeared plateaus remain in the I-V curve, but are not\ncentered at the currents $I=n e \\omega /2\\pi$. For $\\nu < 1/2$ rounded plateaus\ncentered around the quantized current values are found. The possibility of\nusing mode locking in FQHE point contacts as a current-to-frequency standard is\ndiscussed.",
        "category": "cond-mat"
    },
    {
        "text": "Liquid-gas phase behavior of polydisperse dipolar hard-sphere fluid:\n  Extended thermodynamic perturbation theory for central force associating\n  potential: The liquid-gas phase diagram for polydisperse dipolar hard-sphere fluid with\npolydispersity in the hard-sphere size and dipolar moment is calculated using\nextension of the recently proposed thermodynamic perturbation theory for\ncentral force (TPT-CF) associating potential. To establish the connection with\nthe phase behavior of ferrocolloidal dispersions it is assumed that the dipole\nmoment is proportional to the cube of the hard-sphere diameter. We present and\ndiscuss the full phase diagram, which includes cloud and shadow curves,\nbinodals and distribution functions of the coexisting daughter phases at\ndifferent degrees of the system polydispersity. In all cases studied\npolydispersity increases the region of the phase instability and shifts the\ncritical point to the higher values of the temperature and density. The larger\nsize particles always fractionate to the liquid phase and the smaller size\nparticles tend to move to the gas phase. At relatively high values of the\nsystem polydispersity three-phase coexistence is observed.",
        "category": "cond-mat"
    },
    {
        "text": "Tungsten material properties at high temperature and high stress: Recently reported results on the long lifetime of the tungsten samples under\nhigh temperature and high stress conditions expected in the Neutrino Factory\ntarget have strengthened the case for a solid target option for the Neutrino\nFactory. In order to study in more details the behaviour of basic material\nproperties of tungsten, a new method has been developed for measurement of\ntungsten Young's modulus at high stress, high strain-rates (> 1000 s^-1) and\nvery high temperatures (up to 2650 C). The method is based on measurements of\nthe surface motion of tungsten wires, stressed by a pulsed current, using a\nLaser Doppler Vibrometer. The measured characteristic frequencies of wire\nexpansion and contraction under the thermal loading have been used to directly\nobtain the tungsten Young's modulus as a function of applied stress and\ntemperature. The experimental results have been compared with modelling results\nand we have found that they agree very well. From the point of view of future\nuse of tungsten as a high power target material, the most important result of\nthis study is that Young's modulus of tungsten remains high at high\ntemperature, high stress and high strain-rates.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamics of point Josephson junctions in a microstrip line: We analyze a new long wave model describing the electrodynamics of an array\nof point Josephson junctions in a superconducting cavity. It consists in a wave\nequation with Dirac delta function sine nonlinearities. We introduce an adapted\nspectral problem whose spectrum gives the resonances in the current-voltage\ncharacteristic curve of any array. Using the associated inner product and\neigenmodes, we establish that at the resonances the solution is described by\ntwo simple ordinary differential equations.",
        "category": "cond-mat"
    },
    {
        "text": "Finite-frequency prethermalization in periodically driven ergodic\n  systems: We investigate the periodically driven dynamics of many-body systems, either\nclassical or quantum, finite-dimensional or mean-field, displaying an unbounded\nphase-space. We find that the inclusion of a smooth periodic drive atop an\notherwise ergodic dynamics leads to a long-lived prethermalization, even at\nmoderate driving frequencies. In specific asymptotic limits, we compute the\ncorresponding prethermal Hamiltonian from an analytical perturbation scheme.",
        "category": "cond-mat"
    },
    {
        "text": "Thermal Schwinger Effect: Defect Production in Compressed Filament\n  Bundles: We discuss the response of biopolymer filament bundles bound by transient\ncross linkers to compressive loading. These systems admit a mechanical\ninstability at stresses typically below that of traditional Euler buckling. In\nthis instability, there is thermally-activated pair production of topological\ndefects that generate localized regions of bending -- kinks. These kinks\nshorten the bundle's effective length thereby reducing the elastic energy of\nthe mechanically loaded structure. This effect is the thermal analog of the\nSchwinger effect, in which a sufficiently large electric field causes\nelectron-positron pair production. We discuss this analogy and describe the\nimplications of this analysis for the mechanics of biopolymer filament bundles\nof various types under compression.",
        "category": "cond-mat"
    },
    {
        "text": "Modelling the Berezinskii-Kosterlitz-Thouless Transition in the\n  NiGa_2S_4: In the two-dimensional superfluidity, the proliferation of the vortices and\nthe anti-vortices results in a new class of phase transition,\nBerezinskii-Kosterlitz-Thouless (BKT) transition. This class of the phase\ntransitions is also anticipated in the two-dimensional magnetic systems.\nHowever, its existence in the real magnetic systems still remains mysterious.\nHere we propose a phenomenological model to illustrate that the novel\nspin-freezing transition recently uncovered in the NMR experiment on the\nNiGa_2S_4 compound is the BKT-type. The novel spin-freezing state observed in\nthe NiGa_2S_4 possesses the power-law decayed spin correlation.",
        "category": "cond-mat"
    },
    {
        "text": "A proposal of an orbital-dependent correlation energy functional for\n  energy-band calculations: An explicitly orbital-dependent correlation energy functional is proposed,\nwhich is to be used in combination with the orbital-dependent exchange energy\nfunctional in energy-band calculations. It bears a close resemblance to the\nsecond-order direct and exchange perturbation terms calculated with Kohn-Sham\norbitals and Kohn-Sham energies except that one of the two Coulomb interactions\nentering each term is replaced by an effective interaction which contains\ninformation about long-, intermediate-, and short-range correlations beyond\nsecond-order perturbation theory. Such an effective interaction can rigorously\nbe defined for the correlation energy of the uniform electron liquid and is\nevaluated with high accuracy in order to apply to the orbital-dependent\ncorrelation energy functional. The coupling-constant-averaged spin-parallel and\nspin-antiparallel pair correlation functions are also evaluated with high\naccuracy for the electron liquid. The present orbital-dependent correlation\nenergy functional with the effective interaction borrowed from the electron\nliquid is valid for tightly-binding electrons as well as for nearly-free\nelectrons in marked contrast with the conventional local density approximation.",
        "category": "cond-mat"
    },
    {
        "text": "Detection of qubit-oscillator entanglement in nanoelectromechanical\n  systems: Experiments over the past years have demonstrated that it is possible to\nbring nanomechanical resonators and superconducting qubits close to the quantum\nregime and to measure their properties with an accuracy close to the Heisenberg\nuncertainty limit. Therefore, it is just a question of time before we will\nroutinely see true quantum effects in nanomechanical systems. One of the\nhallmarks of quantum mechanics is the existence of entangled states. We propose\na realistic scenario making it possible to detect entanglement of a mechanical\nresonator and a qubit in a nanoelectromechanical setup. The detection scheme\ninvolves only standard current and noise measurements of an atomic point\ncontact coupled to an oscillator and a qubit. This setup could allow for the\nfirst observation of entanglement between a continuous and a discrete quantum\nsystem in the solid state.",
        "category": "cond-mat"
    },
    {
        "text": "How crosslink numbers shape the large-scale physics of cytoskeletal\n  materials: Cytoskeletal networks are the main actuators of cellular mechanics, and a\nfoundational example for active matter physics. In cytoskeletal networks,\nmotion is generated on small scales by filaments that push and pull on each\nother via molecular-scale motors. These local actuations give rise to large\nscale stresses and motion. To understand how microscopic processes can give\nrise to self-organized behavior on larger scales it is important to consider\nwhat mechanisms mediate long-ranged mechanical interactions in the systems. Two\nscenarios have been considered in the recent literature. The first are systems\nwhich are relatively sparse, in which most of the large scale momentum transfer\nis mediated by the solvent in which cytoskeletal filaments are suspended. The\nsecond, are systems in which filaments are coupled via crosslink molecules\nthroughout. Here, we review the differences and commonalities between the\nphysics of these two regimes. We also survey the literature for the numbers\nthat allow us to place a material within either of these two classes.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetocaloric effect in the high-temperature antiferromagnet YbCoC2: The magnetic $H$-$T$ phase diagram and magnetocaloric effect in the recently\ndiscovered high-temperature heavy-fermion compound YbCoC$_2$ have been studied.\nWith the increase in the external magnetic field YbCoC$_2$ experiences the\nmetamagnetic transition and then transition to the ferromagnetic state. The\ndependencies of magnetic entropy change -$\\Delta S_m (T)$ have segments with\npositive and negative magnetocaloric effects for $\\Delta H \\leq 6$~T. For\n$\\Delta H = 9$~T magnetocaloric effect becomes positive with a maximum value of\n-$\\Delta S_m (T)$ is 4.1 J / kg K and a refrigerant capacity is 56.6 J / kg.",
        "category": "cond-mat"
    },
    {
        "text": "Strong photon coupling to the quadrupole moment of an electron in solid\n  state: The implementation of circuit quantum electrodynamics allows coupling distant\nqubits by microwave photons hosted in on-chip superconducting resonators.\nTypically, the qubit-photon interaction is realized by coupling the photons to\nthe electric dipole moment of the qubit. A recent proposal suggests storing the\nquantum information in the electric quadrupole moment of an electron in a\ntriple quantum dot. The qubit is expected to have improved coherence since it\nis insensitive to dipolar noise produced by distant voltage fluctuators. Here\nwe experimentally realize a quadrupole qubit in a linear array of three quantum\ndots in a GaAs/AlGaAs heterostructure. A high impedance microwave resonator\ncoupled to the middle dot interacts with the qubit quadrupole moment. We\ndemonstrate strong quadrupole qubit--photon coupling and observe improved\ncoherence properties when operating the qubit in the parameter space where the\ndipole coupling vanishes.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum spin liquid in antiferromagnetic chain S=1/2 with Acoustic\n  Phonons: A spin and phonon excitations spectrum are studied using quantum Monte Carlo\nmethod in antiferromagnetic chain with spins $S=1/2$ coupled nonadiabaticity\nwith acoustic phonons . It is found the critical coupling exists to open gap in\nthe triplet excitation spectrum for any phonon velocity. The phase boundaries\nof delocalized phonons and propagated the bound states of magnon and a phonon\nare calculated. It is shown that the spherical symmetry of the spin-spin\ncorrelation functions is broken . The magnetic and optical properties $CuGeO_3$\nare explained without using spin-Peierls transition.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Hall effect in a p-type heterojunction with a lateral surface\n  quantum dot superlattice: The quantization of Hall conductance in a p-type heterojunction with lateral\nsurface quantum dot superlattice is investigated. The topological properties of\nthe four-component hole wavefunction are studied both in r- and k-spaces. New\nmethod of calculation of the Hall conductance in a 2D hole gas described by the\nLuttinger Hamiltonian and affected by lateral periodic potential is proposed,\nbased on the investigation of four-component wavefunction singularities in\nk-space. The deviations from the quantization rules for Hofstadter \"butterfly\"\nfor electrons are found, and the explanation of this effect is proposed. For\nthe case of strong periodic potential the mixing of magnetic subbands is taken\ninto account, and the exchange of the Chern numbers between magnetic subands is\ndiscussed.",
        "category": "cond-mat"
    },
    {
        "text": "Photo-induced superconducting-like response in strongly correlated\n  systems: We propose a novel mechanism for the photo-induced superconducting-like\nresponse recently reported in cuprates and other strongly correlated materials.\nThis mechanism relies on quantum-fluctuating bosons consisting of electron\npairs. With periodic drive, the electron pairs and vacancies of pairs form a\ncoherent non-equilibrium condensate, different from conventional\nsuperconductors, yet showing superconducting-like response in some regimes even\nwith dissipation. Unlike the case of driven fermionic bands which results in\nthe familiar Floquet bands with hybridization gaps, for driven bosons the \"gap\"\nopens up in the momentum direction, resulting in a resonant region in momentum\nspace where the eigenvalues are complex. We give a simple physical argument why\nthis picture leads to a \"perfect conductor\" which exhibits superconducting-like\nfrequency-dependent conductivity but no Meissner response. While our model is\nquite general, in the case of cuprates, quantum-fluctuating pair density wave\nin the pseudogap region may serve as the origin of the quantum-fluctuating\nelectron pairs.",
        "category": "cond-mat"
    },
    {
        "text": "Flavors of Magnetic Noise in Quantum Materials: The complexity of electronic band structures in quantum materials offers new\ncharge-neutral degrees of freedom stable for transport, a promising example\nbeing the valley (axial) degree of freedom in Weyl semimetals (WSMs). A\nnoninvasive probe of their transport properties is possible by exploiting the\nfrequency dependence of the magnetic noise generated in the vicinity of the\nmaterial. In this work, we investigate the magnetic noise generically\nassociated with diffusive transport using a systematic Langevin approach.\nTaking a minimal model of magnetic WSMs for demonstration, we show that thermal\nfluctuations of the charge current, the valley current, and the magnetic order\ncan give rise to magnetic noise with distinctively different spectral\ncharacters, which provide a theoretical guidance to separate their\ncontributions. Our approach is extendable to the study of magnetic noise and\nits spectral features arising from other transport degrees of freedom in\nquantum materials.",
        "category": "cond-mat"
    },
    {
        "text": "General solution to inhomogeneous dephasing and smooth pulse dynamical\n  decoupling: In order to achieve the high-fidelity quantum control needed for a broad\nrange of quantum information technologies, reducing the effects of noise and\nsystem inhomogeneities is an essential task. It is well known that a system can\nbe decoupled from noise or made insensitive to inhomogeneous dephasing\ndynamically by using carefully designed pulse sequences based on square or\ndelta-function waveforms such as Hahn spin echo or CPMG. However, such ideal\npulses are often challenging to implement experimentally with high fidelity.\nHere, we uncover a new geometrical framework for visualizing all possible\ndriving fields, which enables one to generate an unlimited number of smooth,\nexperimentally feasible pulses that perform dynamical decoupling or dynamically\ncorrected gates to arbitrarily high order. We demonstrate that this scheme can\nsignificantly enhance the fidelity of single-qubit operations in the presence\nof noise and when realistic limitations on pulse rise times and amplitudes are\ntaken into account.",
        "category": "cond-mat"
    },
    {
        "text": "Electric Circuit Simulation of Floquet Topological Insulators: We present a method for simulating any non-interacting and time-periodic\ntight-binding Hamiltonian in Fourier space using electric circuits made of\ninductors and capacitors. We first map the time-periodic Hamiltonian to a\nFloquet Hamiltonian, which converts the time dimension into a Floquet\ndimension. In electric circuits, this Floquet dimension is simulated as an\nextra spatial dimension without any time dependency in the electrical elements.\nThe number of replicas needed in the Floquet Hamiltonian depends on the\nfrequency and strength of the drive. We also demonstrate that we can detect the\ntopological edge states (including the anomalous edge states in the dynamical\ngap) in an electric circuit by measuring the two-point impedance between the\nnodes. Our method paves a simple and promising way to explore and control\nFloquet topological phases in electric circuits.",
        "category": "cond-mat"
    },
    {
        "text": "Protein folding simulations with Interacting Growth Walk model: We demonstrate that the recently proposed interacting growth walk (IGW)\nmodel, modified for generating self-avoiding heteropolymers, proves to be a\nsimpler alternative to the other Monte Carlo methods available in the\nliterature for obtaining minimum energy conformation of lattice proteins. In\nfact, this simple growth algorithm seems to be capable of quickly leading to\nlow energy states for all the three dimensional bench mark HP-sequences\ninvestigated.",
        "category": "cond-mat"
    },
    {
        "text": "Intrinsic Response of Graphene Vapor Sensors: Graphene is a purely two-dimensional material that has extremely favorable\nchemical sensor properties. It is known, however, that conventional\nnanolithographic processing typically leaves a resist residue on the graphene\nsurface, whose impact on the sensor characteristics of the system has not yet\nbeen determined. Here we show that the contamination layer both degrades the\nelectronic properties of the graphene and masks graphene s intrinsic sensor\nresponses. The contamination layer chemically dopes the graphene, enhances\ncarrier scattering, and acts as an absorbent layer that concentrates analyte\nmolecules at the graphene surface, thereby enhancing the sensor response. We\ndemonstrate a cleaning process that verifiably removes the contamination on the\ndevice structure and allows the intrinsic chemical responses of graphene to be\nmeasured.",
        "category": "cond-mat"
    },
    {
        "text": "Simplistic Coulomb forces in molecular dynamics: Comparing the Wolf and\n  shifted-force approximations: This paper compares the Wolf method to the shifted forces (SF) method for\nefficient computer simulation of isotropic systems interacting via Coulomb\nforces, taking results from the Ewald summation method as representing the true\nbehavior. We find that for the Hansen-McDonald molten salt model the SF\napproximation overall reproduces the structural and dynamical properties as\naccurately as does the Wolf method. It is shown that the optimal Wolf damping\nparameter depends on the property in focus, and that neither the potential\nenergy nor the radial distribution function are useful measures for the\nconvergence of theWolf method to the Ewald summation method. The SF\napproximation is also tested for the SPC/Fw model of liquid water at room\ntemperature, showing good agreement with both the Wolf and the particle mesh\nEwald methods; this confirms previous findings [Fennell & Gezelter, J. Chem.\nPhys. {\\bf 124}, 234104 (2006)]. Beside its conceptualsimplicity the SF\napproximation implies a speed-up of a factor 2 to 3 compared to the Wolf method\n(which is in turn much faster than the Ewald method).",
        "category": "cond-mat"
    },
    {
        "text": "Signatures of topological Josephson junctions: Quasiparticle poisoning and diabatic transitions may significantly narrow the\nwindow for the experimental observation of the $4\\pi$-periodic $dc$ Josephson\neffect predicted for topological Josephson junctions. Here, we show that\nswitching current measurements provide accessible and robust signatures for\ntopological superconductivity which persist in the presence of quasiparticle\npoisoning processes. Such measurements provide access to the phase-dependent\nsubgap spectrum and Josephson currents of the topological junction when\nincorporating it into an asymmetric SQUID together with a conventional\nJosephson junction with large critical current. We also argue that pump-probe\nexperiments with multiple current pulses can be used to measure the\nquasiparticle poisoning rates of the topological junction. The proposed\nsignatures are particularly robust, even in the presence of Zeeman fields and\nspin-orbit coupling, when focusing on short Josephson junctions. Finally, we\nalso consider microwave excitations of short topological Josephson junctions\nwhich may complement switching current measurements.",
        "category": "cond-mat"
    },
    {
        "text": "Weak chaos and fractional dynamics in an optically driven colloidal ring: Three colloidal spheres driven around a ring-like optical trap known as an\noptical vortex have been predicted to undergo periodic collective motion due to\ntheir hydrodynamic coupling. In fact, the quenched disorder in the\noptically-implemented potential energy landscape drives a transition to\ninstability evolving into microscopic weak chaos with fractional dynamics. As a\nresult, the relation between the space-time selfsimilarity of the system's\ncollective transport properties and its microscopic weak chaos dynamics is\nrevealed.",
        "category": "cond-mat"
    },
    {
        "text": "Optically-induced magnetization switching in NiCo2O4 thin films using\n  ultrafast lasers: Recently, all-optical magnetization control has been garnering considerable\nattention in realizing next-generation ultrafast magnetic information devices.\nHere, employing a magneto-optical Kerr effect (MOKE) microscope, we observed\nthe laser-induced magnetization switching of ferrimagnetic oxide NiCo2O4 (NCO)\nepitaxial thin films with perpendicular magnetic anisotropy, where the sample\nwas pumped at 1030-nm laser pulses, and magnetic domain images were acquired\nvia the MOKE microscope with a white light emitting diode. Laser pulses\nirradiated an NCO thin film at various temperatures from 300 K to 400 K while\naltering the parameters of pulse interval, fluence, and the number of pulses\nwith the absence of the external magnetic field. We observed accumulative\nall-optical switching at 380 K and above. Our observation of oxide NCO thin\nfilms facilitates the realization of chemically stable magnetization switching\nusing ultrafast lasers, and without applying a magnetic field.",
        "category": "cond-mat"
    },
    {
        "text": "Pressure-enhanced ferromagnetism in layered CrSiTe3 flakes: The research on van der Waals (vdW) layered ferromagnets have promoted the\ndevelopment of nanoscale spintronics and applications. However, low-temperature\nferromagnetic properties of these materials greatly hinder their applications.\nHere, we report pressure-enhanced ferromagnetic behaviours in layered CrSiTe3\nflakes revealed by high-pressure magnetic circular dichroism (MCD) measurement.\nAt ambient pressure, CrSiTe3 undergoes a paramagnetic-to-ferromagnetic phase\ntransition at 32.8 K, with a negligible hysteresis loop, indicating a soft\nferromagnetic behaviour. Under 4.6 GPa pressure, the soft ferromagnet changes\ninto hard one, signalled by a rectangular hysteretic loop with remnant\nmagnetization at zero field. Interestingly, with further increasing pressure,\nthe coercive field (H_c) dramatically increases from 0.02 T at 4.6 GPa to 0.17\nT at 7.8 GPa, and the Curie temperature (T_c^h: the temperature for closing the\nhysteresis loop) also increases from ~36 K at 4.6 GPa to ~138 K at 7.8 GPa. The\ninfluences of pressure on exchange interactions are further investigated by\ndensity functional theory calculations, which reveal that the in-plane\nnearest-neighbor exchange interaction and magneto-crystalline anisotropy\nincrease simultaneously as pressure increases, leading to increased H_c and\nT_c^h in experiments. The effective interaction between magnetic couplings and\nexternal pressure offers new opportunities for both searching room-temperature\nlayered ferromagnets and designing pressure-sensitive magnetic functional\ndevices.",
        "category": "cond-mat"
    },
    {
        "text": "Method of Image and Transmission through Semi-infinite Nanowires: The method of functional integral bosonization is extended to examine the\ntransmission properties of semi-infinite nanowires. In particular, it is shown\nthat edge states will arise at the end point of the dimerized semi-infinite\nspin-chain and by combining the method of image and the bosonization technique,\nthe system can be properly bosonized. Based on the bosonized action and a\nrenormalization group analysis, it is shown that unlike scattering due to\nsingle bulk impurity in the nanowire, the scattering potential remains relevant\neven for slightly attractive potential due to the interaction between the edge\nstate and its image. When the strength of potential goes beyond a critical\nstrength, the tip of the semi-infinite nanowire may become insulating.",
        "category": "cond-mat"
    },
    {
        "text": "Tuning the confinement potential between spinons in the Ising chain\n  CoNb2O6 using longitudinal fields and quantitative determination of the\n  microscopic Hamiltonian: The Ising chain realizes the fundamental paradigm of spin fractionalization,\nwhere locally flipping a spin creates two domain walls (spinons) that can\nseparate apart at no energy cost. In a quasi-one-dimensional system, the\nmean-field effects of the weak three-dimensional couplings confine the spinons\ninto a Zeeman ladder of two-spinon bound states. Here, we experimentally tune\nthe confinement potential between spinons in the quasi-one-dimensional Ising\nferromagnet CoNb2O6 by means of an applied magnetic field with a large\ncomponent along the Ising direction. Using high-resolution single crystal\ninelastic neutron scattering, we directly observe how the spectrum evolves from\nthe limit of very weak confinement at low field (with many closely-spaced bound\nstates with energies scaling as the field strength to the power 2/3) to very\nstrong confinement at high field (where it consists of a magnon and a\ndispersive two-magnon bound state, with a linear field dependence). At\nintermediate fields, we explore how the higher-order bound states disappear\nfrom the spectrum as they move to higher energies and overlap with the\ntwo-particle continuum. By performing a global fit to the observed spectrum in\nzero field and high field applied along two orthogonal directions, combined\nwith a quantitative parameterization of the interchain couplings, we propose a\nrefined single chain and interchain Hamiltonian that quantitatively reproduces\nall observed dispersions and their field dependence.",
        "category": "cond-mat"
    },
    {
        "text": "Mode specific electronic friction in dissociative chemisorption on metal\n  surfaces: H$_2$ on Ag(111): Electronic friction and the ensuing nonadiabatic energy loss play an\nimportant role in chemical reaction dynamics at metal surfaces. Using molecular\ndynamics with electronic friction evaluated on-the-fly from Density Functional\nTheory, we find strong mode dependence and a dominance of nonadiabatic energy\nloss along the bond stretch coordinate for scattering and dissociative\nchemisorption of H$_2$ on the Ag(111) surface. Exemplary trajectories with\nvarying initial conditions indicate that this mode-specificity translates into\nmodulated energy loss during a dissociative chemisorption event. Despite minor\nnonadiabatic energy loss of about 5\\%, the directionality of friction forces\ninduces dynamical steering that affects individual reaction outcomes,\nspecifically for low-incidence energies and vibrationally excited molecules.\nMode-specific friction induces enhanced loss of rovibrational rather than\ntranslational energy and will be most visible in its effect on final energy\ndistributions in molecular scattering experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Deriving GENERIC from a generalized fluctuation symmetry: Much of the structure of macroscopic evolution equations for relaxation to\nequilibrium can be derived from symmetries in the dynamical fluctuations around\nthe most typical trajectory. For example, detailed balance as expressed in\nterms of the Lagrangian for the path-space action leads to gradient zero-cost\nflow. We find a new such fluctuation symmetry that implies GENERIC, an\nextension of gradient flow where a Hamiltonian part is added to the dissipative\nterm in such a way as to retain the free energy as Lyapunov function.",
        "category": "cond-mat"
    },
    {
        "text": "A theory for the effect of patch / non-patch attractions on the\n  self-assembly of patchy colloids: In this paper, we develop a thermodynamic perturbation theory to describe the\nself-assembly of patchy colloids which exhibit both patch-patch attractions as\nwell as patch / non-patch attractions. That is, patches attract other patches\nas well as the no patch region. In general these attractions operate on\ndifferent energy scales, which allows for controlled self-assembly as well as\nanomalous phase behavior. As an application we apply the model to the study of\nliquid water.",
        "category": "cond-mat"
    },
    {
        "text": "Visibility study of graphene multilayer structures: The visibility of graphene sheets on different types of substrates has been\ninvestigated both theoretically and experimentally. Although single layer\ngraphene is observable on various types of dielectrics under an optical\nmicroscope, it is invisible when it is placed directly on most of the\nsemiconductor and metallic substrates. We show that coating of a resist layer\nwith optimum thickness is an effective way to enhance the contrast of graphene\non various types of substrates and makes single layer graphene visible on most\nsemiconductor and metallic substrates. Experiments have been performed to\nverify the results on quartz and NiFe-coated Si substrates. The results\nobtained will be useful for fabricating graphene-based devices on various types\nof substrates for electronics, spintronics and optoelectronics applications.",
        "category": "cond-mat"
    },
    {
        "text": "Antiferromagnetic ordering and dipolar interactions of YbAlO$_3$: In this paper we report low-temperature magnetic properties of the rare-earth\nperovskite material YbAlO$_3$. Results of elastic and inelastic neutron\nscattering experiment, magnetization measurements along with the crystalline\nelectrical field (CEF) calculations suggest that the ground state of Yb moments\nis a strongly anisotropic Kramers doublet, and the moments are confined in the\n$ab$-plane, pointing at an angle of $\\varphi = \\pm 23.5^{\\circ}$ to the\n$a$-axis. With temperature decreasing below $T_{\\rm N}=0.88$ K, Yb moments\norder into the coplanar, but non-collinear antiferromagnetic (AFM) structure\n$AxGy$, where the moments are pointed along their easy-axes. In addition, we\nhighlight the importance of the dipole-dipole interaction, which selects the\ntype of magnetic ordering and may be crucial for understanding magnetic\nproperties of other rare-earth orthorhombic perovskites. Further analysis of\nthe broad diffuse neutron scattering shows that one-dimensional interaction\nalong the $c$-axis is dominant, and suggests YbAlO$_3$ as a new member of one\ndimensional quantum magnets.",
        "category": "cond-mat"
    },
    {
        "text": "Superconducting microwave resonators with non-centrosymmetric\n  nonlinearity: We investigated both theoretically and experimentally open-ended coplanar\nwaveguide resonators with rf SQUIDs embedded in the central conductor at\ndifferent positions. These rf SQUIDs can be tuned by an external magnetic field\nand thus may exhibit the non-centrosymmetric nonlinearity of $\\chi^{(2)}$ type\nwith suppressed Kerr nonlinearity. We demonstrated that this nonlinearity\nallows for efficient mixing of $\\lambda/2$ and $\\lambda$ modes in the cavity\nand thus enables various parametric effects with three wave mixing. These\neffects are the second harmonic generation, the half tone generation, the\nparametric amplification in both degenerate and non-degenerate regimes and\ndeamplification in degenerate regime.",
        "category": "cond-mat"
    },
    {
        "text": "Thermoelectric properties of Wigner crystal in two-dimensional periodic\n  potential: We study numerically transport and thermoelectric properties of electrons\nplaced in a two-dimensional (2D) periodic potential. Our results show that the\ntransition from sliding to pinned phase takes place at a certain critical\namplitude of lattice potential being similar to the Aubry transition for the\none-dimensional Frenkel-Kontorova model. We show that the 2D Aubry pinned phase\nis characterized by high values of Seebeck coefficient S = 12. At the same time\nwe find that the value of Seebeck coefficient is significantly influenced by\nthe geometry of periodic potential. We discuss possibilities to test the\nproperties of 2D Aubry phase with electrons on a surface of liquid helium.",
        "category": "cond-mat"
    },
    {
        "text": "Theoretical prediction of Curie temperature in two-dimensional\n  ferromagnetic monolayer: Theoretical prediction of Curie temperature (TC) is of vital importance for\ndesigning the spintronic devices in two-dimensional (2D) ferromagnetic\nmaterials. Herein, based on the extensive investigation of Monte Carlo\nsimulations, we summary and propose an improved method to estimate TC more\nprecisely, which includes the different contributions of multiple near-neighbor\ninteractions. Taking monolayer CrI3 as an example, the trends of TC with\nbiaxial strain are investigated via Monte Carlo simulations, mean-field\nformulas and our method. Besides, our method is not only accurate and\nconvenient to predicting the TC in 2D ferromagnetic honeycomb lattice CrI3 but\nit can be extended for predicting the TC of other 2D lattices. Our work paves\nthe way to accelerate the prediction and discovery of novel 2D ferromagnets for\nspintronic applications.",
        "category": "cond-mat"
    },
    {
        "text": "A microscopic theory of Curzon-Ahlborn heat engine: Abstract The Curzon-Ahlborn (CA) efficiency, as the efficiency at the maximum\npower (EMP) of the endoreversible Carnot engine, has a significant impact on\nfinite-time thermodynamics. However, the CA engine model is based on many\nassumptions. In the past few decades, although a lot of efforts have been made,\na microscopic theory of the CA engine is still lacking. By adopting the method\nof the stochastic differential equation of energy, we formulate a microscopic\ntheory of the CA engine realized with an underdamped Brownian particle in a\nclass of non-harmonic potentials. This theory gives microscopic interpretation\nof all assumptions made by Curzon and Ahlborn, and thus puts the results about\nCA engine on a solid foundation. Also, based on this theory, we obtain\nanalytical expressions of the power and the efficiency statistics for the\nBrownian CA engine. Our research brings new perspectives to experimental\nstudies of finite-time microscopic heat engines featured with fluctuations.",
        "category": "cond-mat"
    },
    {
        "text": "Soft self-assembled nanoparticles with temperature-dependent properties: The fabrication of versatile building blocks that are reliably self-assemble\ninto desired ordered and disordered phases is amongst the hottest topics in\ncontemporary material science. To this end, microscopic units of varying\ncomplexity, aimed at assembling the target phases, have been thought, designed,\ninvestigated and built. Such a path usually requires laborious fabrication\ntechniques, especially when a specific funcionalisation of the building blocks\nis required. Telechelic star polymers, i.e., star polymers made of a number $f$\nof di-block copolymers consisting of solvophobic and solvophilic monomers\ngrafted on a central anchoring point, spontaneously self-assemble into soft\npatchy particles featuring attractive spots (patches) on the surface. Here we\nshow that the tunability of such a system can be widely extended by controlling\nthe physical and chemical parameters of the solution. Indeed, at fixed external\nconditions the self-assembly behaviour depends only on the number of arms\nand/or on the ratio of solvophobic to solvophilic monomers. However, changes in\ntemperature and/or solvent quality makes it possible to reliably change the\nnumber and size of the attractive patches. This allows to steer the mesoscopic\nself-assembly behaviour without modifying the microscopic constituents.\nInterestingly, we also demonstrate that diverse combinations of the parameters\ncan generate stars with the same number of patches but different radial and\nangular stiffness. This mechanism could provide a neat way of further\nfine-tuning the elastic properties of the supramolecular network without\nchanging its topology.",
        "category": "cond-mat"
    },
    {
        "text": "Diffusion and localization for the Chirikov typical map: We consider the classical and quantum properties of the \"Chirikov typical\nmap\", proposed by Boris Chirikov in 1969. This map is obtained from the well\nknown Chirikov standard map by introducing a finite number $T$ of random phase\nshift angles. These angles induce a random behavior for small time scales\n($t<T$) and a $T$-periodic iterated map which is relevant for larger time\nscales ($t>T$). We identify the classical chaos border $k_c\\sim T^{-3/2} \\ll 1$\nfor the kick parameter $k$ and two regimes with diffusive behavior on short and\nlong time scales. The quantum dynamics is characterized by the effect of\nChirikov localization (or dynamical localization). We find that the\nlocalization length depends in a subtle way on the two classical diffusion\nconstants in the two time-scale regime.",
        "category": "cond-mat"
    },
    {
        "text": "Bounds on current fluctuations in periodically driven systems: Small nonequilibrium systems in contact with a heat bath can be analyzed with\nthe framework of stochastic thermodynamics. In such systems, fluctuations,\nwhich are not negligible, follow universal relations such as the fluctuation\ntheorem. More recently, it has been found that, for nonequilibrium stationary\nstates, the full spectrum of fluctuations of any thermodynamic current is\nbounded by the average rate of entropy production and the average current.\nHowever, this bound does not apply to periodically driven systems, such as heat\nengines driven by periodic variation of the temperature and artificial\nmolecular pumps driven by an external protocol. We obtain a universal bound on\ncurrent fluctuations for periodically driven systems. This bound is a\ngeneralization of the known bound for stationary states. In general, the\naverage rate that bounds fluctuations in periodically driven systems is\ndifferent from the rate of entropy production. We also obtain a local bound on\nfluctuations that leads to a trade-off relation between speed and precision in\nperiodically driven systems, which constitutes a generalization to periodically\ndriven systems of the so called thermodynamic uncertainty relation. From a\ntechnical perspective, our results are obtained with the use of a recently\ndeveloped theory for 2.5 large deviations for Markov jump processes with\ntime-periodic transition rates.",
        "category": "cond-mat"
    },
    {
        "text": "Slow crack propagation through a disordered medium: Critical transition\n  and dissipation: We show that the intermittent and self-similar fluctuations displayed by a\nslow crack during the propagation in a heterogeneous medium can be\nquantitatively described by an extension of a classical statistical model for\nfracture. The model yields the correct dynamical and morphological scaling, and\nallows to demonstrate that the scale invariance originates from the presence of\na non-equilibrium, reversible, critical transition which in the presence of\ndissipation gives rise to self organized critical behaviour.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of sub-kelvin superconductivity in Cd$_3$As$_2$ thin films: We report the first experimental observation of superconductivity in\nCd$_3$As$_2$ thin films without application of external pressure. Surface\nstudies suggest that the observed transport characteristics are related to the\npolycrystalline continuous part of investigated films with homogeneous\ndistribution of elements and the Cd-to-As ratio close to stoichiometric\nCd$_3$As$_2$. The latter is also supported by Raman spectra of the studied\nfilms, which are similar to those of Cd$_3$As$_2$ single crystals. The\nformation of superconducting phase in films under study is confirmed by the\ncharacteristic behavior of temperature and magnetic field dependence of samples\nresistances, as well as by the presence of pronounced zero-resistance plateaux\nin $dV/dI$ characteristics. The corresponding $H_c-T_c$ plots reveal a clearly\npronounced linear behavior within the intermediate temperature range, similar\nto that observed for bulk Cd$_3$As$_2$ and Bi$_2$Se$_3$ films under pressure,\nsuggesting the possibility of nontrivial pairing in the films under\ninvestigation. We discuss a possible role of sample inhomogeneities and crystal\nstrains in the observed phenomena.",
        "category": "cond-mat"
    },
    {
        "text": "A curious relationship between Potts glass models: A Potts glass model proposed by Nishimori and Stephen[H. Nishimori and M. J.\nStephen, Phys. Rev. B 27, 5644 (1983)] is analyzed by means of the replica mean\nfield theory. This model is a discrete model, has a gauge symmetry, and is\ncalled the Potts gauge glass model. By comparing the present results with the\nresults of the conventional Potts glass model, we find the coincidences and\ndifferences between the models. We find a coincidence that the property for the\nPotts glass phase in this model is coincident with that in the conventional\nmodel at the mean field level. We find a difference that, unlike in the case of\nthe conventional $p$-state Potts glass model, this system for large $p$ does\nnot become ferromagnetic at low temperature under a concentration of\nferromagnetic interaction. The present results support the act of numerically\ninvestigating the present model for study of the Potts glass phase in finite\ndimensions.",
        "category": "cond-mat"
    },
    {
        "text": "Tailoring population inversion in Landau-Zener-St\u00fcckelberg\n  interferometry of flux qubits: We distinguish different mechanisms for population inversion in flux qubits\ndriven by dc+ac magnetic fields. We show that for driving amplitudes such that\nthere are Landau-Zener-St\\\"uckelberg intereferences, it is possible to have\npopulation inversion solely mediated by the environmental bath at long driving\ntimes. We study the effect of the resonant frequency $\\Omega_p$ of the\nmeasuring circuit, finding different regimes for the asymptotic population of\nthe state of the flux qubit. By tailoring $\\Omega_p$ the degree of population\ninversion can be controlled. Our studies are based on realistic simulations of\nthe device for the Josephson flux qubit using the Floquet-Born-Markov\nformalism.",
        "category": "cond-mat"
    },
    {
        "text": "An analysis of localization transitions using non-parametric\n  unsupervised learning: We propose a new viewpoint on the study of localization transitions in\ndisordered quantum systems, showing how critical properties can be seen also as\na geometric transition in the data space generated by the classically encoded\nconfigurations of the disordered quantum system. We showcase our approach to\nthe Anderson model on regular random graphs, known for displaying features of\ninteracting systems, despite being a single-particle problem. We estimate the\ntransition point and critical exponents in agreement with the best-known\nresults in the literature. We provide a simple and coherent explanation of our\nfindings, discussing the applicability of the method in real-world scenarios\nwith a modest number of measurements.",
        "category": "cond-mat"
    },
    {
        "text": "Memristive Reservoirs Learn to Learn: Memristive reservoirs draw inspiration from a novel class of neuromorphic\nhardware known as nanowire networks. These systems display emergent brain-like\ndynamics, with optimal performance demonstrated at dynamical phase transitions.\nIn these networks, a limited number of electrodes are available to modulate\nsystem dynamics, in contrast to the global controllability offered by\nneuromorphic hardware through random access memories. We demonstrate that the\nlearn-to-learn framework can effectively address this challenge in the context\nof optimization. Using the framework, we successfully identify the optimal\nhyperparameters for the reservoir. This finding aligns with previous research,\nwhich suggests that the optimal performance of a memristive reservoir occurs at\nthe `edge of formation' of a conductive pathway. Furthermore, our results show\nthat these systems can mimic membrane potential behavior observed in spiking\nneurons, and may serve as an interface between spike-based and continuous\nprocesses.",
        "category": "cond-mat"
    },
    {
        "text": "Quasi-free-standing AA-stacked bilayer graphene induced by calcium\n  intercalation of the graphene-silicon carbide interface: We study quasi-freestanding bilayer graphene on silicon carbide intercalated\nby calcium. The intercalation, and subsequent changes to the system, were\ninvestigated by low-energy electron diffraction, angle-resolved photoemission\nspectroscopy (ARPES) and density-functional theory (DFT). Calcium is found to\nintercalate only at the graphene-SiC interface, completely displacing the\nhydrogen terminating SiC. As a consequence, the system becomes highly n-doped.\nComparison to DFT calculations shows that the band dispersion, as determined by\nARPES, deviates from the band structure expected for Bernal-stacked bilayer\ngraphene. Instead, the electronic structure closely matches AA-stacked bilayer\ngraphene on Ca-terminated SiC, indicating a spontaneous transition from AB- to\nAA-stacked bilayer graphene following calcium intercalation of the underlying\ngraphene-SiC interface.",
        "category": "cond-mat"
    },
    {
        "text": "Multivalley effective mass theory simulation of donors in silicon: Last year, Salfi et al. made the first direct measurements of a donor wave\nfunction and found extremely good theoretical agreement with atomistic\ntight-binding [Salfi et al., Nat. Mater. 13, 605 (2014)]. Here, we show that\nmulti-valley effective mass theory, applied properly, does achieve close\nagreement with tight-binding and hence gives reliable predictions. To\ndemonstrate this, we variationally solve the coupled six-valley Shindo-Nara\nequations, including silicon's full Bloch functions. Surprisingly, we find that\nincluding the full Bloch functions necessitates a tetrahedral, rather than\nspherical, donor central cell correction to accurately reproduce the\nexperimental energy spectrum of a phosphorus impurity in silicon. We\ncross-validate this method against atomistic tight-binding calculations,\nshowing that the two theories agree well for the calculation of donor-donor\ntunnel coupling. Further, we benchmark our results by performing a statistical\nuncertainty analysis, confirming that derived quantities such as the wave\nfunction profile and tunnel couplings are robust with respect to variational\nenergy fluctuations. Finally, we apply this method to exhaustively enumerate\nthe tunnel coupling for all donor-donor configurations within a large search\nvolume, demonstrating conclusively that the tunnel coupling has no spatially\nstable regions. Though this instability is problematic for reliably coupling\ndonor pairs for two-qubit operations, we identify specific target locations\nwhere donor qubits can be placed with scanning tunneling microscopy technology\nto achieve reliably large tunnel couplings.",
        "category": "cond-mat"
    },
    {
        "text": "A tight-binding approach to uniaxial strain in graphene: We analyze the effect of tensional strain in the electronic structure of\ngraphene. In the absence of electron-electron interactions, within linear\nelasticity theory, and a tight-binding approach, we observe that strain can\ngenerate a bulk spectral gap. However this gap is critical, requiring threshold\ndeformations in excess of 20%, and only along preferred directions with respect\nto the underlying lattice. The gapless Dirac spectrum is robust for small and\nmoderate deformations, and the gap appears as a consequence of the merging of\nthe two inequivalent Dirac points, only under considerable deformations of the\nlattice. We discuss how strain-induced anisotropy and local deformations can be\nused as a means to affect transport characteristics and pinch off current flow\nin graphene devices.",
        "category": "cond-mat"
    },
    {
        "text": "Colloidal Hard Spheres: Triumphs, Challenges and Mysteries: The simplicity of hard spheres as a model system is deceptive. Although the\nparticles interact solely through volume exclusion, that nevertheless suffices\nfor a wealth of static and dynamical phenomena to emerge, making the model an\nimportant target for achieving a comprehensive understanding of matter. In\naddition, while real colloidal suspensions are typically governed by complex\ninteractions, Pusey and Van Megen [Nature 320 340--342 (1986)] demonstrated\nthat suitably tuned suspensions result in hard-sphere like behavior, thus\nbringing a valuable experimental complement to the celebrated theoretical\nmodel. Colloidal hard spheres are thus both a material in their own right and a\nplatform upon which phenomena exhibited by simple materials can be explored in\ngreat detail. These various purposes enable a particular synergy between\nexperiment, theory and computer simulation. Here we review the extensive body\nof work on hard spheres, ranging from their equilibrium properties such as\nphase behavior, interfaces and confinement to some of the non--equilibrium\nphenomena they exhibit such as sedimentation, glass formation and nucleation.",
        "category": "cond-mat"
    },
    {
        "text": "Minimum vertex cover problems on random hypergraphs: replica symmetric\n  solution and a leaf removal algorithm: We study minimum vertex cover problems on random \\alpha-uniform hypergraphs\nusing two different approaches, a replica method in statistical mechanics of\nrandom systems and a leaf removal algorithm. It is found that there exists a\nphase transition at the critical average degree e/(\\alpha-1). Below the\ncritical degree, a replica symmetric ansatz in the statistical-mechanical\nmethod holdsand the algorithm estimates a solution of the problem which\ncoincide with that by the replica method. In contrast, above the critical\ndegree, the replica symmetric solution becomes unstable and these methods fail\nto estimate the exact solution.These results strongly suggest a close relation\nbetween the replica symmetry and the performance of approximation algorithm.",
        "category": "cond-mat"
    },
    {
        "text": "Competition between heavy-fermion and Kondo interaction in isoelectronic\n  A-site ordered perovskites: With current research efforts shifting towards the 4$d$ and 5$d$ transition\nmetal oxides, understanding the evolution of the electronic and magnetic\nstructure as one moves away from 3$d$ materials is of critical importance. Here\nwe perform X-ray spectroscopy and electronic structure calculations on $A$-site\nordered perovskites with Cu in the $A$-site and the $B$-sites descending along\nthe 9th group of the periodic table to elucidate the emerging properties as\n$d$-orbitals change from partially filled 3$d$, 4$d$, to 5$d$. The results show\nthat when descending from Co to Ir the charge transfers from the cuprate like\nZhang-Rice state on Cu to the t$_{2g}$ orbital of the B site. As the Cu\n$d$-orbital occupation approaches the Cu$^{2+}$ limit, a mixed-valence state in\nCaCu$_3$Rh$_4$O$_{12}$ and heavy fermion state in CaCu$_3$Ir$_4$O$_{12}$ are\nobtained. The investigated d-electron compounds are mapped onto the Doniach\nphase diagram of the competing RKKY and Kondo interactions developed for\nf-electron systems.",
        "category": "cond-mat"
    },
    {
        "text": "Study of implosion in an attractive Bose-Einstein condensate: By solving the Gross-Pitaevskii equation analytically and numerically, we\nreexamine the implosion phenomena that occur beyond the critical value of the\nnumber of atoms of an attractive Bose-Einstein condensate (BEC) with\ncigar-shape trapping geometry. We theoretically calculate the critical number\nof atoms in the condensate by using Ritz's variational optimization technique\nand investigate the stability and collapse dynamics of the attractive BEC by\nnumerically solving the time dependent Gross-Pitavskii equation.",
        "category": "cond-mat"
    },
    {
        "text": "Fermi surface truncation from thermal nematic fluctuations: We analyze how thermal fluctuations near a finite temperature nematic phase\ntransition affect the spectral function $A({\\bf k},\\omega)$ for single-electron\nexcitations in a two-dimensional metal. Perturbation theory yields a splitting\nof the quasi-particle peak with a d-wave form factor, reminiscent of a\npseudogap. We present a resummation of contributions to all orders in the\nGaussian fluctuation regime. Instead of a splitting, the resulting spectral\nfunction exhibits a pronounced broadening of the quasi-particle peak, which\nvaries strongly around the Fermi surface and vanishes upon approaching the\nBrillouin zone diagonal. The Fermi surface obtained from a Brillouin zone plot\nof $A({\\bf k},0)$ seems truncated to Fermi arcs.",
        "category": "cond-mat"
    },
    {
        "text": "Showcasing the necessity of the principle of relative motion in physical\n  statistics: Inconsistency of the `segmented Fermi surface': The hunt for exotic properties in flowing systems is a popular and active\nfield of study, and has recently gained renewed attention through claims such\nas a ``segmented Fermi surface'' in a superconducting system that hosts steady\nsuperflow of screening current driven by an external field. Apart from this\nexcitement and the promise of hosting Majorana zero modes, claims such as this\nimply exotic gap-to-gapless quantum phase transitions merely through boost of\ninertial frames of observation, and challenge the very concept behind the\nprinciple of relative motion. Here, we first illustrate an obvious inescapable\nphysical inconsistency of such claims concerning the flow velocity. Taking into\naccount this basic principle from the beginning, we then demonstrate that a\nproper employment of physical statistics naturally reproduces the experimental\nobservation without causing such a conceptual crisis. This example showcases\nthe importance of strict adherence to the basic principle of relative motion in\nphysical statistics, especially when pushing the frontiers of physics and\ntechnology.",
        "category": "cond-mat"
    },
    {
        "text": "Heat convection and radiation in flighted rotary kilns: A minimal model: We propose a minimal model aiming to describe heat transfer between particles\n(i.e. grains) and gases in a model of flighted rotary kilns. It considers a\nchannel in which a convective gas interacts with a granular suspension and a\ngranular bed. Despite its simplicity it captures the main experimental findings\nin the case of dilute suspension of heavy grains typical of what can be\nobserved in many industrial rotary kilns. Energy balance between each phase\ntakes into account the main heat transfer mechanisms between the transverse\ngranular motion and the convective gas. In the absence of radiation heat\ntransfer, the model predicts exponential variations of the temperatures\ncharacterized by a length which depends on the granular and gas heat flow rates\nas well as on the exchange areas. When radiation is taken into account, the\nmodel can be solved numerically. For this case, the temperature variations can\nbe fitted by stretched exponentials whose parameters are found to be\nindependent of the studied phases. Finally, an efficiency criterion is proposed\nto optimize the length of the system.",
        "category": "cond-mat"
    },
    {
        "text": "Temperature evolution of spin accumulation detected electrically in a\n  nondegenerated silicon channel: We study temperature evolution of spin accumulation signals obtained by the\nthree-terminal Hanle effect measurements in a nondegenerated silicon channel\nwith a Schottky-tunnel-barrier contact. We find the clear difference in the\ntemperature-dependent spin signals between spin-extraction and spin-injection\nconditions. In a spin-injection condition with a low bias current, the\nmagnitude of spin signals can be enhanced despite the rise of temperature. For\nthe interpretation of the temperature-dependent spin signals, it is important\nto consider the sensitivity of the spin detection at the\nSchottky-tunnel-barrier contact in addition to the spin diffusion in Si.",
        "category": "cond-mat"
    },
    {
        "text": "Structure of BSCCO supermodulation from ab initio calculations: We present results of density functional theory (DFT) calculation of the\nstructural supermodulation in BSCCO-2212 structure, and show that the\nsupermodulation is indeed a spontaneous symmetry breaking of the nominal\ncrystal symmetry, rather than a phenomenon driven by interstitial O dopants.\nThe structure obtained is in excellent quantitative agreement with recent x-ray\nstudies, and reproduces several qualitative aspects of scanning tunnelling\nmicroscopy (STM) experiments as well. The primary structural modulation\naffecting the CuO_2 plane is found to be a buckling wave of tilted CuO_5\nhalf-octahedra, with maximum tilt angle near the phase of the supermodulation\nwhere recent STM experiments have discovered an enhancement of the\nsuperconducting gap. We argue that the tilting of the half-octahedra and\nconcommitant planar buckling are directly modulating the superconducting pair\ninteraction.",
        "category": "cond-mat"
    },
    {
        "text": "Giant Nernst effect in the crossover between Fermi liquid and strange\n  metal: The strange-metal state is a crucial problem in condensed matter physics\nhighlighted by its ubiquity in almost all major correlated systems[1-7]. Its\nunderstanding could provide important insight into high-Tc superconductivity[2]\nand quantum criticality[8]. However, with the Fermi liquid theory failing in\nstrange metals, understanding the highly unconventional behaviors has been a\nlong-standing challenge. Fundamental aspects of strange metals remain elusive,\nincluding the nature of their charge carriers[1]. Here, we report the\nobservation of a giant Nernst response in the strange-metal state in a\ntwo-dimensional superconductor 2M-WS2. A giant Nernst coefficient comparable to\nthe vortex Nernst signal in superconducting cuprates, and its high sensitivity\nto carrier mobility, are found when the system enters the strange-metal state\nfrom the Fermi liquid state. The temperature and magnetic field dependence of\nthe giant Nernst peak rule out the relevance of both Landau quasiparticles and\nsuperconductivity. Instead, the giant Nernst peak at the crossover indicates a\ndramatic change in carrier entropy when entering the strange-metal state. The\npresence of such an anomalous Nernst response is further confirmed in other\niconic strange metals, suggesting its universality and places stringent\nexperimental constraints on the mechanism of strange metals.",
        "category": "cond-mat"
    },
    {
        "text": "From Coherent Modes to Turbulence and Granulation of Trapped Gases: The process of exciting the gas of trapped bosons from an equilibrium initial\nstate to strongly nonequilibrium states is described as a procedure of symmetry\nrestoration caused by external perturbations. Initially, the trapped gas is\ncooled down to such low temperatures, when practically all atoms are in\nBose-Einstein condensed state, which implies the broken global gauge symmetry.\nExcitations are realized either by imposing external alternating fields,\nmodulating the trapping potential and shaking the cloud of trapped atoms, or it\ncan be done by varying atomic interactions by means of Feshbach resonance\ntechniques. Gradually increasing the amount of energy pumped into the system,\nwhich is realized either by strengthening the modulation amplitude or by\nincreasing the excitation time, produces a series of nonequilibrium states,\nwith the growing fraction of atoms for which the gauge symmetry is restored. In\nthis way, the initial equilibrium system, with the broken gauge symmetry and\nall atoms condensed, can be excited to the state, where all atoms are in the\nnormal state, with completely restored gauge symmetry. In this process, the\nsystem, starting from the regular superfluid state, passes through the states\nof vortex superfluid, turbulent superfluid, heterophase granular fluid, to the\nstate of normal chaotic fluid in turbulent regime. Both theoretical and\nexperimental studies are presented.",
        "category": "cond-mat"
    },
    {
        "text": "Butterfly hysteresis loop at non-zero bias field in antiferromagnetic\n  molecular rings: cooling by adiabatic magnetization: At low temperatures, the magnetization of the molecular ferric wheel NaFe$_6$\nexhibits a step at a critical field $B_c$ due to a field-induced\nlevel-crossing. By means of high-field torque magnetometry we observed a\nhysteretic behavior at the level-crossing with a characteristic butterfly shape\nwhich is analyzed in terms of a dissipative two-level model. Several unusual\nfeatures were found. The non-zero bias field of the level-crossing suggests the\npossibility of cooling by adiabatic magnetization.",
        "category": "cond-mat"
    },
    {
        "text": "Microtubules: Montroll's kink and Morse vibrations: Using a version of Witten's supersymmetric quantum mechanics proposed by\nCaticha, we relate Montroll's kink to a traveling, asymmetric Morse double-well\npotential suggesting in this way a connection between kink modes and\nvibrational degrees of freedom along microtubules",
        "category": "cond-mat"
    },
    {
        "text": "Striped Ferronematic ground states in a spin-orbit coupled $S=1$ Bose\n  gas: We theoretically establish the mean-field phase diagram of a homogeneous\nspin-$1$, spin-orbit coupled Bose gas as a function of the spin-dependent\ninteraction parameter, the Raman coupling strength and the quadratic Zeeman\nshift. We find that the interplay between spin-orbit coupling and\nspin-dependent interactions leads to the occurrence of ferromagnetic or\nferronematic phases which also break translational symmetry. For weak Raman\ncoupling, increasing attractive spin-dependent interactions (as in $^{87}$Rb or\n$^7$Li) induces a transition from a uniform to a stripe XY ferromagnet (with no\nnematic order). For repulsive spin-dependent interactions however (as in\n$^{23}$Na), we find a transition from an $XY$ spin spiral phase ($<S_{z} >= 0$\nand uniform total density) with uniaxial nematic order, to a biaxial\nferronematic, where the total density, spin vector and nematic director\noscillate in real space. We investigate the stability of these phases against\nthe quadratic Zeeman effect, which generally tends to favor uniform phases with\neither ferromagnetic or nematic order but not both. We discuss the relevance of\nour results to ongoing experiments on spin-orbit coupled, spinor Bose gases.",
        "category": "cond-mat"
    },
    {
        "text": "Dirty Weyl fermions: rare region effects near 3D Dirac points: We study three-dimensional Dirac fermions with weak finite-range scalar\npotential disorder. We show that even though disorder is perturbatively\nirrelevant at 3D Dirac points, nonperturbative effects from rare regions give\nrise to a nonzero density of states and a finite mean free path, with the\ntransport at the Dirac point being dominated by hopping between rare regions.\nAs one moves in chemical potential away from the Dirac point, there are\ninteresting intermediate-energy regimes where the rare regions produce\nscattering resonances that determine the DC conductivity. We also discuss the\ninterplay of disorder with interactions at the Dirac point. Attractive\ninteractions drive a transition into a granular superconductor, with a critical\ntemperature that depends strongly on the disorder distribution. In the presence\nof Coulomb repulsion and weak retarded attraction, the system can be a Bose\nglass. Our results apply to all 3D systems with Dirac points, including Weyl\nsemimetals, and overturn a thirty year old consensus regarding the irrelevance\nof weak disorder at 3D Dirac points.",
        "category": "cond-mat"
    },
    {
        "text": "Orbital-Peierls State in NaTiSi2O6: Does the quasi one-dimensional titanium pyroxene NaTiSi2O6 exhibit the novel\n{\\it orbital-Peierls} state? We calculate its groundstate properties by three\nmethods: Monte Carlo simulations, a spin-orbital decoupling scheme and a\nmapping onto a classical model. The results show univocally that for the spin\nand orbital ordering to occur at the same temperature --an experimental\nobservation-- the crystal field needs to be small and the orbitals are active.\nWe also find that quantum fluctuations in the spin-orbital sector drive the\ntransition, explaining why canonical bandstructure methods fail to find it. The\nconclusion that NaTiSi2O6 shows an orbital-Peierls transition is therefore\ninevitable.",
        "category": "cond-mat"
    },
    {
        "text": "From Floquet to Dicke: quantum spin-Hall insulator interacting with\n  quantum light: Time-periodic perturbations due to classical electromagnetic fields are\nuseful to engineer the topological properties of matter using the Floquet\ntheory. Here we investigate the effect of quantized electromagnetic fields by\nfocusing on the quantized light-matter interaction on the edge state of a\nquantum spin-Hall insulator. A Dicke-type superradiant phase transition occurs\nat arbitrary weak coupling, the electronic spectrum acquires a finite gap and\nthe resulting ground state manifold is topological with Chern number $\\pm 1$.\nWhen the total number of excitations is conserved, a photocurrent is generated\nalong the edge, being pseudo-quantized as $\\omega\\ln(1/\\omega)$ in the low\nfrequency limit, and decaying as $1/\\omega$ for high frequencies with $\\omega$\nthe photon frequency. The photon spectral function exhibits a clean Goldstone\nmode, a Higgs like collective mode at the optical gap and the polariton\ncontinuum.",
        "category": "cond-mat"
    },
    {
        "text": "Transport via classical percolation at quantum Hall plateau transitions: We consider transport properties of disordered two-dimensional electron gases\nunder high perpendicular magnetic field, focusing in particular on the peak\nlongitudinal conductivity $\\sigma_{xx}^\\mathrm{peak}$ at the quantum Hall\nplateau transition. We use a local conductivity model, valid at temperatures\nhigh enough such that quantum tunneling is suppressed, taking into account the\nrandom drift motion of the electrons in the disordered potential landscape and\ninelastic processes provided by electron-phonon scattering. A diagrammatic\nsolution of this problem is proposed, which leads to a rich interplay of\nconduction mechanisms, where classical percolation effects play a prominent\nrole. The scaling function for $\\sigma_{xx}^\\mathrm{peak}$ is derived in the\nhigh temperature limit, which can be used to extract universal critical\nexponents of classical percolation from experimental data.",
        "category": "cond-mat"
    },
    {
        "text": "Flat band induced non-Fermi liquid behavior of multicomponent fermions: We investigate multicomponent fermions in a flat band and predict\nexperimental signatures of non-Fermi liquid behavior. We use dynamical\nmean-field theory to obtain the density, double occupancy and entropy in a Lieb\nlattice for $\\mathcal{N} = 2$ and $\\mathcal{N} = 4$ components. We derive a\nmean-field scaling relation between the results for different values of\n$\\mathcal{N}$, and study its breakdown due to beyond-mean field effects. The\npredicted signatures occur at temperatures above the N\\'eel temperature and\npersist in presence of a harmonic trapping potential, thus they are observable\nwith current ultracold gas experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Liquid n-hexane condensed in silica nanochannels: A combined optical\n  birefringence and vapor sorption isotherm study: The optical birefringence of liquid n-hexane condensed in an array of\nparallel silica channels of 7nm diameter and 400 micrometer length is studied\nas a function of filling of the channels via the vapor phase. By an analysis\nwith the generalized Bruggeman effective medium equation we demonstrate that\nsuch measurements are insensitive to the detailed geometrical (positional)\narrangement of the adsorbed liquid inside the channels. However, this technique\nis particularly suitable to search for any optical anisotropies and thus\ncollective orientational order as a function of channel filling. Nevertheless,\nno hints for such anisotropies are found in liquid n-hexane. The n-hexane\nmolecules in the silica nanochannels are totally orientationally disordered in\nall condensation regimes, in particular in the film growth as well as in the\nthe capillary condensed regime. Thus, the peculiar molecular arrangement found\nupon freezing of liquid n-hexane in nanochannel-confinement, where the\nmolecules are collectively aligned perpendicularly to the channels' long axes,\ndoes not originate in any pre-alignment effects in the nanoconfined liquid due\nto capillary nematization.",
        "category": "cond-mat"
    },
    {
        "text": "Coulomb-interaction induced incomplete shell filling in the hole system\n  of InAs quantum dots: We have studied the hole charging spectra of self-assembled InAs quantum dots\nin perpendicular magnetic fields by capacitance-voltage spectroscopy. From the\nmagnetic field dependence of the individual peaks we conclude that the s-like\nground state is completely filled with two holes but that the fourfold\ndegenerate p-shell is only half filled with two holes before the filling of the\nd-shell starts. The resulting six-hole ground state is highly polarized. This\nincomplete shell filling can be explained by the large influence of the Coulomb\ninteraction in this system.",
        "category": "cond-mat"
    },
    {
        "text": "Callen-Welton fluctuation dissipation theorem and Nyquist theorem as a\n  consequence of detailed balance principle applied to an oscillator: We re-derive the Nyquist theorem and Callen-Welton fluctuation-dissipation\ntheorem (FDT) as a consequence of detailed balance principle applied to a\nharmonic oscillator. The usage of electrical notions in the beginning makes the\nconsideration understandable for every physicists. Perhaps it is the simplest\nderivation of these well-known theorems in statistical physics. The classical\nlimit is understandable as a consequence of Waterston-Herapath equipartition\ntheorem.",
        "category": "cond-mat"
    },
    {
        "text": "Geometrical barriers and the growth of flux domes in thin ideal\n  superconducting disks: When an ideal (no bulk pinning) flat type-II superconducting disk is\nsubjected to a perpendicular magnetic field H_a, the first vortex nucleates at\nthe rim when H_a = H_0, the threshold field, and moves quickly to the center of\nthe disk. As H_a increases above H_0, additional vortices join the others, and\ntogether they produce a domelike field distribution of radius b. In this paper\nI present analytic solutions for the resulting magnetic-field and\nsheet-current-density distributions. I show how these distributions vary as b\nincreases with H_a, and I calculate the corresponding field-increasing\nmagnetization.",
        "category": "cond-mat"
    },
    {
        "text": "Anomalous Polymer Dynamics Is Non-Markovian: Memory Effects and The\n  Generalized Langevin Equation Formulation: Any first course on polymer physics teaches that the dynamics of a tagged\nmonomer of a polymer is anomalously subdiffusive, i.e., the mean-square\ndisplacement of a tagged monomer increases as $t^\\alpha$ for some $\\alpha<1$\nuntil the terminal relaxation time $\\tau$ of the polymer. Beyond time $\\tau$\nthe motion of the tagged monomer becomes diffusive. Classical examples of\nanomalous dynamics in polymer physics are single polymeric systems, such as\nphantom Rouse, self-avoiding Rouse, self-avoiding Zimm, reptation,\ntranslocation through a narrow pore in a membrane, and many-polymeric systems\nsuch as polymer melts. In this pedagogical paper I report that all these\ninstances of anomalous dynamics in polymeric systems are robustly characterized\nby power-law memory kernels within a {\\it unified} Generalized Langevin\nEquation (GLE) scheme, and therefore, are non-Markovian. The exponents of the\npower-law memory kernels are related to the relaxation response of the polymers\nto local strains, and are derived from the equilibrium statistical physics of\npolymers. The anomalous dynamics of a tagged monomer of a polymer in these\nsystems is then reproduced from the power-law memory kernels of the GLE via the\nfluctuation-dissipation theorem (FDT). Using this GLE formulation I further\nshow that the characteristics of the drifts caused by a (weak) applied field on\nthese polymeric systems are also obtained from the corresponding memory\nkernels.",
        "category": "cond-mat"
    },
    {
        "text": "Repulsive van der Waals forces due to hydrogen exposure on bilayer\n  Graphene: We consider the effect of atomic hydrogen exposure to a system of two undoped\nsheets of graphene grown near a silica surface (the first adsorbed to the\nsurface and the second freestanding near the surface). In the absence of atomic\nhydrogen the van der Waals force between the sheets is attractive at all\nseparations causing the sheets to come closer together. However, with addition\nof atomic hydrogen between the sheets the long range van der Waals interaction\nturns repulsive at a critical concentration. The underlying triple layer\nstructure (SiO2 -Atomic Hydrogen Gas -Air) gives rise to a long range repulsion\nthat at large enough separations dominates over the more rapidly decaying\nattraction between the two-dimensional undoped graphene sheets (and between the\nouter graphene sheet and SiO2). This may be an avenue to tune the separation\nbetween two graphene sheets with the gas concentration. Doping of the graphene\nlayers increases the attractive part of the interaction and hence reduces the\nnet repulsive interaction.",
        "category": "cond-mat"
    },
    {
        "text": "Time-dependent quantum transport in a resonant tunnel junction coupled\n  to a nanomechanical oscillator: We present a theoretical study of time-dependent quantum transport in a\nresonant tunnel junction coupled to a nanomechanical oscillator within the\nnon-equilibrium Green's function technique. An arbitrary voltage is applied to\nthe tunnel junction and electrons in the leads are considered to be at zero\ntemperature. The transient and the steady state behavior of the system is\nconsidered here in order to explore the quantum dynamics of the oscillator as a\nfunction of time. The properties of the phonon distribution of the\nnanomechnical oscillator strongly coupled to the electrons on the dot are\ninvestigated using a non-perturbative approach. We consider both the energy\ntransferred from the electrons to the oscillator and the Fano factor as a\nfunction of time. We discuss the quantum dynamics of the nanomechanical\noscillator in terms of pure and mixed states. We have found a significant\ndifference between a quantum and a classical oscillator. In particular, the\nenergy of a classical oscillator will always be dissipated by the electrons\nwhereas the quantum oscillator remains in an excited state. This will provide\nuseful insight for the design of experiments aimed at studying the quantum\nbehavior of an oscillator.",
        "category": "cond-mat"
    },
    {
        "text": "Field-induced transverse spin ordering in FeBr2: Weak first-order phase transitions from axial to oblique spin ordering in\nFeBr2 are evidenced by SQUID magnetometry in axial fields H1(T) above the\nmulticritical point, Hm = 2.4 MA/m, Tm = 4.6 K, and below the\nantiferro-to-paramagnetic phase line, Hc(T), in agreement with recent specific\nheat data (Aruga Katori et al., 1996). The ordering of the in-plane moments is\nprobably due to non-diagonal coupling to the longitudinal ones, both of which\nincrease dis-continuously at H1(T) only under an additional symmetry-breaking\ntransverse field.",
        "category": "cond-mat"
    },
    {
        "text": "Synthesis, Structural, and Transport Properties of Cr-doped BaTi_2As_2O: The interplay between unconventional superconductivity and the ordering of\ncharge/spin density wave is one of the most vital issues in both condensed\nmatter physics and material science. The Ti-based compound BaTi_2As_2O, which\ncan be seen as the parent phase of superconducting BaTi_2Sb_2O, has a layered\nstructure with a space group P4/mmm, similar to that of cuprate and iron-based\nsuperconductors. This material exhibits a charge density wave (CDW) ordering\ntransition revealed by an anomaly at around 200 K in transport measurements.\nHere, we report the synthesis and systematical study of the physical properties\nin Cr-doped BaTi_{2-x}Cr_xAs_2O (x = 0 - 0.154), and demonstrate that the\ntransition temperature of the CDW ordering is suppressed gradually by the doped\nCr element. The magnetization measurements confirm the evolution of the CDW\nordering transition. These observed behaviors are similar to that observed in\niron-based superconductors, but no superconductivity emerges down to 2 K. In\naddition, the first-principles calculations are also carried out for\nwell-understanding the nature of experimental observations.",
        "category": "cond-mat"
    },
    {
        "text": "Broadband probing magnetization dynamics of the coupled vortex state\n  permalloy layers in nanopillars: Broadband magnetization response of coupled vortex state magnetic dots in\nlayered nanopillars was explored as a function of in-plane magnetic field and\ninterlayer separation. For dipolarly coupled circular Py(25 nm)/Cu(20 nm)/Py(25\nnm) nanopillars of 600 nm diameter, a small in-plane field splits the\neigenfrequencies of azimuthal spin wave modes inducing an abrupt transition\nbetween in-phase and out-of-phase kinds of the low-lying coupled spin wave\nmodes. The critical field for this splitting is determined by antiparallel\nchiralities of the vortices in the layers. Qualitatively similar (although more\ngradual) changes occur also in the exchange coupled Py(25 nm)/Cu(1 nm)/Py(25\nnm) tri-layer nanopillars. These findings are in qualitative agreement with\nmicromagnetic dynamic simulations.",
        "category": "cond-mat"
    },
    {
        "text": "X-ray imaging of the dynamic magnetic vortex core deformation: Magnetic platelets with a vortex configuration are attracting considerable\nattention. The discovery that excitation with small in-plane magnetic fields or\nspin polarised currents can switch the polarisation of the vortex core did not\nonly open the possibility of using such systems in magnetic memories, but also\ninitiated the fundamental investigation of the core switching mechanism itself.\nMicromagnetic models predict that the switching is mediated by a\nvortex-antivortex pair, nucleated in a dynamically induced vortex core\ndeformation. In the same theoretical framework, a critical core velocity is\npredicted, above which switching occurs. Although these models are extensively\nstudied and generally accepted, experimental support has been lacking until\nnow. In this work, we have used high-resolution time-resolved X-ray microscopy\nto study the detailed dynamics in vortex structures. We could reveal the\ndynamic vortex core deformation preceding the core switching. Also, the\nthreshold velocity could be measured, giving quantitative comparison with\nmicromagnetic models.",
        "category": "cond-mat"
    },
    {
        "text": "New Monte Carlo method for planar Poisson-Voronoi cells: By a new Monte Carlo algorithm we evaluate the sidedness probability p_n of a\nplanar Poisson-Voronoi cell in the range 3 \\leq n \\leq 1600. The algorithm is\ndeveloped on the basis of earlier theoretical work; it exploits, in particular,\nthe known asymptotic behavior of p_n as n\\to\\infty. Our p_n values all have\nbetween four and six significant digits. Accurate n dependent averages, second\nmoments, and variances are obtained for the cell area and the cell perimeter.\nThe numerical large n behavior of these quantities is analyzed in terms of\nasymptotic power series in 1/n. Snapshots are shown of typical occurrences of\nextremely rare events implicating cells of up to n=1600 sides embedded in an\nordinary Poisson-Voronoi diagram. We reveal and discuss the characteristic\nfeatures of such many-sided cells and their immediate environment. Their\nrelevance for observable properties is stressed.",
        "category": "cond-mat"
    },
    {
        "text": "Surfactant-Mediated Epitaxial Growth of Single-Layer Graphene in an\n  Unconventional Orientation on SiC: We report the use of a surfactant molecule during the epitaxy of graphene on\nSiC(0001) that leads to the growth in an unconventional orientation, namely\n$R0^\\circ$ rotation with respect to the SiC lattice. It yields a very\nhigh-quality single-layer graphene with a uniform orientation with respect to\nthe substrate, on the wafer scale. We find an increased quality and homogeneity\ncompared to the approach based on the use of a pre-oriented template to induce\nthe unconventional orientation. Using spot profile analysis low energy electron\ndiffraction, angle-resolved photoelectron spectroscopy, and the normal\nincidence x-ray standing wave technique, we assess the crystalline quality and\ncoverage of the graphene layer. Combined with the presence of a\ncovalently-bound graphene layer in the conventional orientation underneath, our\nsurfactant-mediated growth offers an ideal platform to prepare epitaxial\ntwisted bilayer graphene via intercalation.",
        "category": "cond-mat"
    },
    {
        "text": "In-plane Magnetization Induced Quantum Anomalous Hall Effect: In a two-dimensional electron gas, the quantized Hall conductance can be\ninduced by a strong magnetic field, known as the quantum Hall effect, and it\ncan also result from the strong exchange coupling of magnetic ions, dubbed as\nthe \"quantum anomalous Hall effect\". The quantum Hall effect requires the\nout-of-plane magnetic field, and similarly, it is commonly believed that the\nmagnetization should be out-of-plane for the quantum anomalous Hall effect. In\nthe present work, we find this condition is not necessary and predict that the\nquantum anomalous Hall effect can also be induced by the purely in-plane\nmagnetization in two realistic systems, including Bi$_2$Te$_3$ thin film with\nmagnetic doping and HgMnTe quantum wells with shear strains, when all the\nreflection symmetries are broken. An experimental setup is proposed to confirm\nthis effect, the observation of which will pave the way to search for the\nquantum anomalous Hall effect in a wider range of materials.",
        "category": "cond-mat"
    },
    {
        "text": "Non-Linear Stochastic Equations with Calculable Steady States: We consider generalizations of the Kardar--Parisi--Zhang equation that\naccomodate spatial anisotropies and the coupled evolution of several fields,\nand focus on their symmetries and non-perturbative properties. In particular,\nwe derive generalized fluctuation--dissipation conditions on the form of the\n(non-linear) equations for the realization of a Gaussian probability density of\nthe fields in the steady state. For the amorphous growth of a single height\nfield in one dimension we give a general class of equations with exactly\ncalculable (Gaussian and more complicated) steady states. In two dimensions, we\nshow that any anisotropic system evolves on long time and length scales either\nto the usual isotropic strong coupling regime or to a linear-like fixed point\nassociated with a hidden symmetry. Similar results are derived for textural\ngrowth equations that couple the height field with additional order parameters\nwhich fluctuate on the growing surface. In this context, we propose\nphenomenological equations for the growth of a crystalline material, where the\nheight field interacts with lattice distortions, and identify two special cases\nthat obtain Gaussian steady states. In the first case compression modes\ninfluence growth and are advected by height fluctuations, while in the second\ncase it is the density of dislocations that couples with the height.",
        "category": "cond-mat"
    },
    {
        "text": "Jamming of packings of frictionless particles with and without shear: By minimizing the enthalpy of packings of frictionless particles, we obtain\njammed solids at desired pressures and hence investigate the jamming transition\nwith and without shear. Typical scaling relations of the jamming transition are\nrecovered in both cases. In contrast to systems without shear, shear-driven\njamming transition occurs at a higher packing fraction and the jammed solids\nare more rigid with an anisotropic force network. Furthermore, by introducing\nthe macro-friction coefficient, we propose an explanation of the packing\nfraction gap between sheared and non-sheared systems at fixed pressure.",
        "category": "cond-mat"
    },
    {
        "text": "Profiles of near-resonant population-imbalanced trapped Fermi gases: We investigate the density profiles of a partially polarized trapped Fermi\ngas in the BCS-BEC crossover region using mean field theory within the local\ndensity approximation. Within this approximation the gas is phase separated\ninto concentric shells. We describe how the structure of these shells depends\nupon the polarization and the interaction strength. A Comparison with\nexperiments yields insight into the possibility of a polarized superfluid\nphase.",
        "category": "cond-mat"
    },
    {
        "text": "On super-Poissonian behavior of the Rosenzweig-Porter model in the\n  non-ergodic extended regime: The Rosenzweig-Porter model has seen a resurgence in interest as it exhibits\na non-ergodic extended phase between the ergodic extended metallic phase and\nthe localized phase. Such a phase is relevant to many physical models from the\nSachdev-Ye-Kitaev model in high-energy physics and quantum gravity, to the\ninteracting many-body localization in condensed matter physics and quantum\ncomputing. This phase is characterized by fractal behavior of the\nwavefunctions, and a postulated correlated mini-band structure of the energy\nspectrum. Here we will seek evidence for the latter in the spectrum. Since this\nbehavior is expected on intermediate energy scales spectral rigidity is a\nnatural way to tease it out. Nevertheless, due to the Thouless energy and\nambiguities in the unfolding procedure, the results are inconclusive. On the\nother hand, by using the singular value decomposition method, clear evidence\nfor a super-Poissonian behavior in this regime emerges, consistent with a\npicture of correlated mini-bands.",
        "category": "cond-mat"
    },
    {
        "text": "Hot 2DHG states in tellurium: Element semiconductor Te is very popular in both fundamental electronic\nstructure study, and device fabrication research area due to its unique band\nstructure. Specifically, in low temperatures, Te possesses strong quantum\noscillations with magnetic field applied in basal plane, either following\nShubnikov-de Haas (SdH) oscillation rule or following log-periodic oscillation\nrule. With magnetic field applied along the [001] direction, the SdH\noscillations are attributed to the two-dimensional hole gas (2DHG) surface\nstates. Here we reported an interesting SdH oscillation in Te-based single\ncrystals, with the magnetic field applied along the [001] direction of the\ncrystals, showing the maximum oscillation intensity at ~ 75 K, and still\ntraceable at 200 K, which indicates a rather hot 2DHG state. The nontrivial\nBerry phase can be also obtained from the oscillations, implying the\ncontribution from topological states. More importantly, the high temperature\nSdH oscillation phenomena are observed in different Te single crystals samples,\nand Te single crystals with nonmagnetic/magnetic dopants, showing robustness to\nbulk defects. Therefore, the oscillation may be contributed by the bulk\nsymmetry protected hot 2DHG states, which will offer a new platform for\nhigh-temperature quantum transport studies.",
        "category": "cond-mat"
    },
    {
        "text": "Spin dynamics at the singlet-triplet crossings in double quantum dot: We simulate the control of the spin states in a two-electron double quantum\ndot when an external detuning potential is used for passing the system through\nan anticrossing. The hyperfine coupling of the electron spins with the\nsurrounding nuclei causes the anticrossing of the spin states but also the\ndecoherence of the spin states. We calculate numerically the singlet-triplet\ndecoherence for different detuning values and find a good agreement with\nexperimental measurement results of the same setup. We predict an interference\neffect due to the coupling of T0 and T+ states.",
        "category": "cond-mat"
    },
    {
        "text": "Influence of the Halide Ion on the A Site Dynamics in FAPbX3 (X = Br and\n  Cl): The optoelectronic properties and ultimately photovoltaic performance of\nhybrid lead halide perovskites, is inherently related to the dynamics of the\norganic cations. Here we report on the dynamics of the formamidinium (FA)\ncation in FAPbX3 perovskites for chloride and bromide varieties, as studied by\nneutron spectroscopy. Elastic fixed window scan measurements showed the onset\nof reorientational motion of FA cations in FAPbCl3 to occur at a considerably\nhigher temperature compared to that in FAPbBr3. In addition, we observed two\ndistinct dynamical transitions only in the chloride system, suggesting a\nsignificant variation in the reorientational motions of the FA cation with\ntemperature. Quasielastic neutron scattering data analysis of FAPbCl3 showed\nthat in the low temperature orthorhombic phase, FA cations undergo 2-fold jump\nreorientations about the C-H axis which evolve into an isotropic rotation in\nthe intermediate tetragonal and high temperature cubic phases. Comparing the\nresults with those from FAPbBr3, reveal that the time scale, barrier to\nreorientation and the geometry of reorientational motion of the FA cation are\nsignificantly different for the two halides. We note that this dependence of\nthe dynamic properties of the A-site cation on the halide, is unique to the FA\nseries; the geometry of methylammonium (MA) cation dynamics in MAPbX3 is known\nto be insensitive to different halides.",
        "category": "cond-mat"
    },
    {
        "text": "Ab initio calculation of carrier mobility in semiconductors including\n  ionized-impurity scattering: The past decade has seen the emergence of ab initio computational methods for\ncalculating phonon-limited carrier mobilities in semiconductors with predictive\naccuracy. More realistic calculations ought to take into account additional\nscattering mechanisms such as, for example, impurity and grain-boundary\nscattering. In this work, we investigate the effect of ionized-impurity\nscattering on the carrier mobility. We model the impurity potential by a\ncollection of randomly distributed Coulomb scattering centers, and we include\nthis relaxation channel into the ab initio Boltzmann transport equation, as\nimplemented in the EPW code. We demonstrate this methodology by considering\nsilicon, silicon carbide, and gallium phosphide, for which detailed\nexperimental data are available. Our calculations agree reasonably well with\nexperiments over a broad range of temperatures and impurity concentrations. For\neach compound investigated here, we compare the relative importance of\nelectron-phonon scattering and ionized-impurity scattering, and we critically\nassess the reliability of Matthiessen's rule. We also show that an accurate\ndescription of dielectric screening and carrier effective masses cam improve\nquantitative agreement with experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Electrically tunable charge and spin transitions in Landau levels of\n  interacting Dirac fermions in trilayer graphene: Trilayer graphene in the fractional Quantum Hall Effect regime displays a set\nof unique interaction-induced transitions that can be tuned entirely by the\napplied bias voltage. These transitions occur near the anti-crossing points of\ntwo Landau levels. In a large magnetic field ($> 8$ T) the electron-electron\ninteractions close the anti-crossing gap, resulting in some unusual transitions\nbetween different Landau levels. For the filling factor $\\nu=\\frac23$, these\ntransitions are accompanied by a change of spin polarization of the ground\nstate. For a small Zeeman energy, this provides an unique opportunity to\ncontrol the spin polarization of the ground state by fine tuning the bias\nvoltage.",
        "category": "cond-mat"
    },
    {
        "text": "Spin relaxation in Mn12-acetate: We present a comprehensive derivation of the magnetization relaxation in a\nMn12-acetate crystal based on thermally assisted spin tunneling induced by\nquartic anisotropy and weak transverse magnetic fields. The overall relaxation\nrate as function of the magnetic field is calculated and shown to agree well\nwith data including all resonance peaks. The Lorentzian shape of the resonances\nis also in good agreement with recent data. A generalized master equation\nincluding resonances is derived and solved exactly. It is shown that many\ntransition paths with comparable weight exist that contribute to the relaxation\nprocess. Previously unknown spin-phonon coupling constants are calculated\nexplicitly.",
        "category": "cond-mat"
    },
    {
        "text": "Evolution of Landau Levels into Edge States at an Atomically Sharp Edge\n  in Graphene: The quantum-Hall-effect (QHE) occurs in topologically-ordered states of\ntwo-dimensional (2d) electron-systems in which an insulating bulk-state\ncoexists with protected 1d conducting edge-states. Owing to a unique\ntopologically imposed edge-bulk correspondence these edge-states are endowed\nwith universal properties such as fractionally-charged quasiparticles and\ninterference-patterns, which make them indispensable components for QH-based\nquantum-computation and other applications. The precise edge-bulk\ncorrespondence, conjectured theoretically in the limit of sharp edges, is\ndifficult to realize in conventional semiconductor-based electron systems where\nsoft boundaries lead to edge-state reconstruction. Using scanning-tunneling\nmicroscopy and spectroscopy to follow the spatial evolution of bulk\nLandau-levels towards a zigzag edge of graphene supported above a graphite\nsubstrate we demonstrate that in this system it is possible to realize\natomically sharp edges with no edge-state reconstruction. Our results single\nout graphene as a system where the edge-state structure can be controlled and\nthe universal properties directly probed.",
        "category": "cond-mat"
    },
    {
        "text": "New Superconducting RbFe2As2: A First-principles Investigation: RbFe2As2 has recently been reported to be a bulk superconductor with Tc = 2.6\nK in the undoped state, in contrast to undoped BaFe2As2 with a magnetic ground\nstate. We present here the results of the first-principles calculations of the\nstructural, elastic and electronic properties for this newest superconductor\nand discuss its behaviour in relation to other related systems.\n  Keywords: RbFe2As2, Electronic structure; Elastic constant;\nSuperconductivity.\n  PACS: 74.70.Dd, 74.10.+v, 74.20.Pq, 75.25.Ld",
        "category": "cond-mat"
    },
    {
        "text": "Superconducting properties of lithium-decorated bilayer graphene: Present study provides a comprehensive theoretical analysis of the\nsuperconducting phase in selected lithium-decorated bilayer graphene\nnanostructures. The numerical calculations, conducted within the Eliashberg\nformalism, give quantitative estimations of the most important thermodynamic\nproperties such as the critical temperature, specific heat, critical field and\nothers. It is shown that discussed lithium-graphene systems present enhancement\nof their thermodynamic properties comparing to the monolayer case e.g. the\ncritical temperature can be raised to $\\sim 15$ K. Furthermore, estimated\ncharacteristic thermodynamic ratios exceed predictions of the\nBardeen-Cooper-Schrieffer theory suggesting that considered lithium-graphene\nsystems can be properly analyzed only within the strong-coupling regime.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical Signatures of Rank-2 $U(1)$ Spin Liquids: Emergent $U(1)$ gauge theories and artificial photons in frustrated magnets\nare outstanding examples of many-body collective phenomena. The classical and\nquantum regimes of these systems provide platforms for classical and quantum\nspin liquids, and are the subject of current active theoretical and\nexperimental investigations. Recently, realizations of rank-2 $U(1)$ (R2-U1)\ngauge theories in three-dimensional frustrated magnets have been proposed. Such\nsystems in the quantum regime may lead to the so-called fracton ordered phases\n-- a new class of topological order that has been associated with quantum\nstabilizer codes and holography. However, there exist few distinguishing\ncharacteristics of these states for their detection in real materials. Here we\nfocus on the classical limit, and present the dynamical spin structure factor\nfor a R2-U1 spin liquid state on a breathing pyrochlore lattice. Remarkably, we\nfind unique signatures of the R2-U1 state, and we contrast them with the\nresults obtained from a more conventional $U(1)$ spin liquid. These results\nprovide a new path of investigation for future inelastic neutron scattering\nexperiments on candidate materials.",
        "category": "cond-mat"
    },
    {
        "text": "Muon-Spin Rotation Spectra in the Mixed Phase of High-T_c\n  Superconductors : Thermal Fluctuations and Disorder Effects: We study muon-spin rotation (muSR) spectra in the mixed phase of highly\nanisotropic layered superconductors, specifically Bi_2+xSr_2-xCaCu_2O_8+delta\n(BSCCO), by modeling the fluid and solid phases of pancake vortices using\nliquid-state and density functional methods. The role of thermal fluctuations\nin causing motional narrowing of muSR lineshapes is quantified in terms of a\nfirst-principles theory of the flux-lattice melting transition. The effects of\nrandom point pinning are investigated using a replica treatment of liquid state\ncorrelations and a replicated density functional theory. Our results indicate\nthat motional narrowing in the pure system, although substantial, cannot\naccount for the remarkably small linewidths obtained experimentally at\nrelatively high fields and low temperatures. We find that satisfactory\nagreement with the muSR data for BSCCO in this regime can be obtained through\nthe ansatz that this ``phase'' is characterized by frozen short-range\npositional correlations reflecting the structure of the liquid just above the\nmelting transition. This proposal is consistent with recent suggestions of a\n``pinned liquid'' or ``glassy'' state of pancake vortices in the presence of\npinning disorder. Our results for the high-temperature liquid phase indicate\nthat measurable linewidths may be obtained in this phase as a consequence of\ndensity inhomogeneities induced by the pinning disorder. The results presented\nhere comprise a unified, first-principles theoretical treatment of muSR spectra\nin highly anisotropic layered superconductors in terms of a controlled set of\napproximations.",
        "category": "cond-mat"
    },
    {
        "text": "Theory of Spin-Resolved Auger-Electron Spectroscopy from Ferromagnetic\n  3d-Transition Metals: CVV Auger electron spectra are calculated for a multi-band Hubbard model\nincluding correlations among the valence electrons as well as correlations\nbetween core and valence electrons. The interest is focused on the\nferromagnetic 3d-transition metals. The Auger line shape is calculated from a\nthree-particle Green function. A realistic one-particle input is taken from\ntight-binding band-structure calculations. Within a diagrammatic approach we\ncan distinguish between the \\textit{direct} correlations among those electrons\nparticipating in the Auger process and the \\textit{indirect} correlations in\nthe rest system. The indirect correlations are treated within second-order\nperturbation theory for the self-energy. The direct correlations are treated\nusing the valence-valence ladder approximation and the first-order perturbation\ntheory with respect to valence-valence and core-valence interactions. The\ntheory is evaluated numerically for ferromagnetic Ni. We discuss the\nspin-resolved quasi-particle band structure and the Auger spectra and\ninvestigate the influence of the core hole.",
        "category": "cond-mat"
    },
    {
        "text": "In situ TEM investigation of oxygen migration as a key mechanism for\n  resistive switching in Pr0.7Ca0.3MnO3: Low temperature growth Pr0.7Ca0.3MnO3 (PCMO) thin film showed high\nperformance in electric field induced resistance switching (RS). To understand\nthe micro-mechanism of RS in Metal/PCMO/Metal devices, structure evolution of\nPCMO under external electric field monitored inside transmission electron\nmicroscope (TEM) were performed. Evolution of the modulation stripe in as-grown\nPCMO sample was investigated when applying electric field. The new-generated\nmodulation stripe gradually disappeared. These results indicate that oxygen ion\nmigration plays a key role in RS.",
        "category": "cond-mat"
    },
    {
        "text": "Contact-Density Analysis of Lattice Polymer Adsorption Transitions: By means of contact-density chain-growth simulations, we investigate a simple\nlattice model of a flexible polymer interacting with an attractive substrate.\nThe contact density is a function of the numbers of monomer-substrate and\nmonomer-monomer contacts. These contact numbers represent natural order\nparameters and allow for a comprising statistical study of the conformational\nspace accessible to the polymer in dependence of external parameters such as\nthe attraction strength of the substrate and the temperature. Since the contact\ndensity is independent of the energy scales associated to the interactions, its\nlogarithm is an unbiased measure for the entropy of the conformational space.\nBy setting explicit energy scales, the thus defined, highly general\nmicrocontact entropy can easily be related to the microcanonical entropy of the\ncorresponding hybrid polymer-substrate system.",
        "category": "cond-mat"
    },
    {
        "text": "High energy pseudogap and its evolution with doping in Fe-based\n  superconductors as revealed by optical spectroscopy: We report optical spectroscopic measurements on electron- and hole-doped\nBaFe2As2. We show that the compounds in the normal state are not simple metals.\nThe optical conductivity spectra contain, in addition to the free carrier\nresponse at low frequency, a temperature-dependent gap-like suppression at\nrather high energy scale near 0.6 eV. This suppression evolves with the\nAs-Fe-As bond angle induced by electron- or hole-doping. Furthermore, the\nfeature becomes much weaker in the Fe-chalcogenide compounds. We elaborate that\nthe feature is caused by the strong Hund's rule coupling effect between the\nitinerant electrons and localized electron moment arising from the multiple Fe\n3d orbitals. Our experiments demonstrate the coexistence of itinerant and\nlocalized electrons in iron-based compounds, which would then lead to a more\ncomprehensive picture about the metallic magnetism in the materials.",
        "category": "cond-mat"
    },
    {
        "text": "Multigap superconductivity in the new BiCh$_{2}$-based layered\n  superconductor La$_\\mathrm{0.7}$Ce$_\\mathrm{0.3}$OBiSSe: The layered bismuth oxy-sulfide materials, which are structurally related to\nthe Fe-pnictides/chalcogenides and cuprates superconductors, have brought\nsubstantial attention for understanding the physics of reduced dimensional\nsuperconductors. We have examined the pairing symmetry of recently discovered\nBiCh$_2$-based superconductor, La$_\\mathrm{1-x}$Ce$_\\mathrm{x}$OBiSSe with $x$\n= 0.3, through transverse field (TF) muon spin rotation measurement, in\naddition we present the results of magnetization, resistivity and zero field\n(ZF) muon spin relaxation measurements. Bulk superconductivity has been\nobserved below 2.7 K for $x$ = 0.3, verified by resistivity and magnetization\ndata. The temperature dependence of the magnetic penetration depth has been\ndetermined from TF-$\\mu$SR data can be described by an isotropic two-gap $s+s$\nwave model compared to a single gap $s$- or anisotropic $s$-wave models, the\nresemblance with Fe-pnictides/chalcogenides and MgB$_2$. Furthermore, from the\nTF-$\\mu$SR data, we have determined the London's penetration depth\n$\\lambda_\\mathrm{L}(0)$ = 452(3) nm, superconducting carrier's density\n$n_\\mathrm{s}$ = 2.18(1) $\\times$10$^{26}$ carriers/m$^{3}$ and effective mass\nenhancement $m^{*}$ = 1.66(1) $m_\\mathrm{e}$, respectively. No signature of\nspontaneous internal field is found down to 100 mK in ZF-$\\mu$SR measurement\nsuggest that time-reversal symmetry is preserved in this system.",
        "category": "cond-mat"
    },
    {
        "text": "Performance Analysis of 60nm gate length III-V InGaAs HEMTs: Simulations\n  vs. experiments: An analysis of recent experimental data for high-performance In0.7Ga0.3As\nhigh electron mobility transistors (HEMTs) is presented. Using a fully quantum\nmechanical, ballistic model, we simulate In0.7Ga0.3As HEMTs with gate lengths\nof LG = 60nm, 85, and 135 nm and compare the result to the measured I-V\ncharacteristics including draininduced barrier lowering, sub-threshold swing,\nand threshold voltage variation with gate insulator thickness, as well as\non-current performance. To first order, devices with three different oxide\nthicknesses and channel lengths can all be described by our ballistic model\nwith appropriate values of parasitic series resistance. For high gate voltages,\nhowever, the ballistic simulations consistently overestimate the measured\non-current, and they do not show the experimentally observed decrease in\non-current with increasing gate length. With no parasitic series resistance at\nall, the simulated on-current of the LG = 60 nm device is about twice the\nmeasured current. According to the simulation, the estimated ballistic carrier\ninjection velocity for this device is about 2.7 x 10^7 cm/s. Because of the\nimportance of the semiconductor capacitance, the simulated gate capacitance is\nabout 2.5 times less than the insulator capacitance. Possible causes of the\ntransconductance degradation observed under high gate voltages in these devices\nare also explored. In addition to a possible gate-voltage dependent scattering\nmechanism, the limited ability of the source to supply carriers to the channel,\nand the effect of nonparabolicity are likely to play a role. The drop in\non-current with increasing gate length is an indication that the devices\noperate below the ballistic limit.",
        "category": "cond-mat"
    },
    {
        "text": "The onset of magnetic order in fcc-Fe films on Cu(100): On the basis of a first-principles electronic structure theory of finite\ntemperature metallic magnetism in layered materials, we investigate the onset\nof magnetic order in thin (2-8 layers) fcc-Fe films on Cu(100) substrates. The\nnature of this ordering is altered when the systems are capped with copper.\nIndeed we find an oscillatory dependence of the Curie temperatures as a\nfunction of Cu-cap thickness, in excellent agreement with experimental data.\nThe thermally induced spin-fluctuations are treated within a mean-field\ndisordered local moment (DLM) picture and give rise to layer-dependent `local\nexchange splittings' in the electronic structure even in the paramagnetic\nphase. These features determine the magnetic intra- and interlayer interactions\nwhich are strongly influenced by the presence and extent of the Cu cap.",
        "category": "cond-mat"
    },
    {
        "text": "Topological phase transition in the quench dynamics of a one-dimensional\n  Fermi gas: We study the quench dynamics of a one-dimensional ultracold Fermi gas in an\noptical lattice potential with synthetic spin-orbit coupling. At equilibrium,\nthe ground state of the system can undergo a topological phase transition and\nbecome a topological superfluid with Majorana edge states. As the interaction\nis quenched near the topological phase boundary, we identify an interesting\ndynamical phase transition of the quenched state in the long-time limit,\ncharacterized by an abrupt change of the pairing gap at a critical quenched\ninteraction strength. We further demonstrate the topological nature of this\ndynamical phase transition from edge-state analysis of the quenched states. Our\nfindings provide interesting clues for the understanding of topological phase\ntransitions in dynamical processes, and can be useful for the dynamical\ndetection of Majorana edge states in corresponding systems.",
        "category": "cond-mat"
    },
    {
        "text": "Novel method for photovoltaic energy conversion using surface acoustic\n  waves in piezoelectric semiconductors: This paper presents a novel principle for photovoltaic (PV) energy conversion\nusing surface acoustic waves (SAWs) in piezoelectric semiconductors. A SAW\nproduces a periodically modulated electric potential, which spatially\nsegregates photoexcited electrons and holes to the maxima and minima of the SAW\npotential. The moving SAW collectively transports the carriers with the speed\nof sound to the electrodes made of different materials, which extract electrons\nand holes separately and generate dc output. The proposed active design is\nexpected to have higher efficiency than passive designs of the existing PV\ndevices and to produce enough energy to sustain the SAW.",
        "category": "cond-mat"
    },
    {
        "text": "Twin-domain formation in epitaxial triangular lattice delafossites: Twin domains are often found as structural defects in symmetry mismatched\nepitaxial thin films. The delafossite ABO2, which has a rhombohedral structure,\nis a good example that often forms twin domains. Although bulk metallic\ndelafossites are known to be the most conducting oxides, the high conductivity\nis yet to be realized in thin film forms. Suppressed conductivity found in thin\nfilms is mainly caused by the formation of twin domains, and their boundaries\ncan be a source of scattering centers for charge carriers. To overcome this\nchallenge, the underlying mechanism for their formation must be understood, so\nthat such defects can be controlled and eliminated. Here, we report the origin\nof structural twins formed in a CuCrO2 delafossite thin film on a substrate\nwith hexagonal or triangular symmetries. A robust heteroepitaxial relationship\nis found for the delafossite film with the substrate, and the surface\ntermination turns out to be critical to determine and control the domain\nstructure of epitaxial delafossites. Based on such discoveries, we also\ndemonstrate a twin-free epitaxial thin films grown on high-miscut substrates.\nThis finding provides an important synthesis strategy for growing single domain\ndelafossite thin films and can be applied to other delafossites for epitaxial\nsynthesis of high-quality thin films.",
        "category": "cond-mat"
    },
    {
        "text": "Influence of the coordination defects on the dynamics and the potential\n  energy landscape of two-dimensional silica: The main cause of the fragile-to-strong crossover of 3D silica was previously\nattributed to the presence of a low energy cutoff in the potential energy\nlandscape. The important question emerges about the microscopic origin of this\ncrossover and the generalizibility to other glass-formers. In this work, the\nfragile-to-strong crossover of a model 2D glassy system is analyzed via\nmolecular dynamics simulation, which represents 2D-silica. By separating the\nsampled defect and defect-free inherent structures, we are able to identify\ntheir respective density of state distributions with respect to energy. A low\nenergy cutoff is found in both distributions. It is shown that the\nfragile-to-strong crossover can be quantitatively related to the parameters of\nthe energy landscape, involving in particular the low-energy cutoff of the\nenergy distribution. It is also shown that the low-energy cutoff of the\ndefect-states is determined by the formation energy of a specific defect\nconfiguration, involving two silicon and no oxygen defect. The low-temperature\nbehavior of 2D silica is quantitatively compared with that of 3D silica,\nshowing surprisingly similar behavior.",
        "category": "cond-mat"
    },
    {
        "text": "Possibility of Electron Pairing in Small Metallic Nanoparticles: We investigate the possibility of electron pairing in small metallic\nnanoparticles at zero temperature. In these particles both electrons and\nphonons are mesoscopic, i.e. modified by the nanoparticle's finite size. The\nelectrons, the phonons, and their interaction are described within the\nframework of a simplified model. The effective electron-electron interaction is\nderived from the underlying electron-phonon interaction. The effect of both\neffective interaction and Coulomb interaction on the electronic spectrum is\nevaluated. Results are presented for aluminum, zinc and potassium nanoparticles\ncontaining a few hundred atoms. We find that a large portion of the aluminum\nand zinc particles exhibit modifications in their electronic spectrum due to\npairing correlations, while pairing correlations are not present in the\npotassium particles.",
        "category": "cond-mat"
    },
    {
        "text": "Molecular Doping of Graphene: Graphene, a one-atom thick zero gap semiconductor [1, 2], has been attracting\nan increasing interest due to its remarkable physical properties ranging from\nan electron spectrum resembling relativistic dynamics [3-12] to ballistic\ntransport under ambient conditions [1-4]. The latter makes graphene a promising\nmaterial for future electronics and the recently demonstrated possibility of\nchemical doping without significant change in mobility has improved graphene's\nprospects further [13]. However, to find optimal dopants and, more generally,\nto progress towards graphene-based electronics requires understanding the\nphysical mechanism behind the chemical doping, which has been lacking so far.\nHere, we present the first joint experimental and theoretical investigation of\nadsorbates on graphene. We elucidate a general relation between the doping\nstrength and whether or not adsorbates have a magnetic moment: The paramagnetic\nsingle NO2 molecule is found to be a strong acceptor, whereas its diamagnetic\ndimer N2O4 causes only weak doping. This effect is related to the peculiar\ndensity of states of graphene, which provides an ideal situation for model\nstudies of doping effects in semiconductors. Furthermore, we explain recent\nresults on its \"chemical sensor\" properties, in particular, the possibility to\ndetect a single NO2 molecule [13].",
        "category": "cond-mat"
    },
    {
        "text": "Temperature dependence of polarization relaxation in semiconductor\n  quantum dots: The decay time of the linear polarization degree of the luminescence in\nstrongly confined semiconductor quantum dots with asymmetrical shape is\ncalculated in the frame of second-order quasielastic interaction between\nquantum dot charge carriers and LO phonons. The phonon bottleneck does not\nprevent significantly the relaxation processes and the calculated decay times\ncan be of the order of a few tens picoseconds at temperature $T \\simeq 100$K,\nconsistent with recent experiments by Paillard et al. [Phys. Rev. Lett.\n{\\bf86}, 1634 (2001)].",
        "category": "cond-mat"
    },
    {
        "text": "Stability and decay of Bloch oscillations in presence of time-dependent\n  nonlinearity: We consider Bloch oscillations of Bose-Einstein condensates in presence of a\ntime-modulated s-wave scattering length. Generically, interaction leads to\ndephasing and decay of the wave packet. Based on a cyclic-time argument, we\nfind---additionally to the linear Bloch oscillation and a rigid soliton\nsolution---an infinite family of modulations that lead to a periodic time\nevolution of the wave packet. In order to quantitatively describe the dynamics\nof Bloch oscillations in presence of time-modulated interactions, we employ two\ncomplementary methods: collective-coordinates and the linear stability analysis\nof an extended wave packet. We provide instructive examples and address the\nquestion of robustness against external perturbations.",
        "category": "cond-mat"
    },
    {
        "text": "Thermal-error regime in high-accuracy gigahertz single-electron pumping: Single-electron pumps based on semiconductor quantum dots are promising\ncandidates for the emerging quantum standard of electrical current. They can\ntransfer discrete charges with part-per-million (ppm) precision in nanosecond\ntime scales. Here, we employ a metal-oxide-semiconductor silicon quantum dot to\nexperimentally demonstrate high-accuracy gigahertz single-electron pumping in\nthe regime where the number of electrons trapped in the dot is determined by\nthe thermal distribution in the reservoir leads. In a measurement with\ntraceability to primary voltage and resistance standards, the averaged pump\ncurrent over the quantized plateau, driven by a \\mbox{$1$-GHz} sinusoidal wave\nin the absence of magnetic field, is equal to the ideal value of $ef$ within a\nmeasurement uncertainty as low as $0.27$~ppm.",
        "category": "cond-mat"
    },
    {
        "text": "Local modes, phonons, and mass transport in solid $^4$He: We propose a model to treat the local motion of atoms in solid $^{4}$He as a\nlocal mode. In this model, the solid is assumed to be described by the Self\nConsistent Harmonic approximation, combined with an array of local modes. We\nshow that in the bcc phase the atomic local motion is highly directional and\ncorrelated, while in the hcp phase there is no such correlation. The correlated\nmotion in the bcc phase leads to a strong hybridization of the local modes with\nthe T$_{1}(110)$ phonon branch, which becomes much softer than that obtained\nthrough a Self Consistent Harmonic calculation, in agreement with experiment.\nIn addition we predict a high energy excitation branch which is important for\nself-diffusion. Both the hybridization and the presence of a high energy branch\nare a consequence of the correlation, and appear only in the bcc phase. We\nsuggest that the local modes can play the role in mass transport usually\nattributed to point defects (vacancies). Our approach offers a more overall\nconsistent picture than obtained using vacancies as the predominant point\ndefect. In particular, we show that our approach resolves the long standing\ncontroversy regarding the contribution of point defects to the specific heat of\nsolid $^{4}$He.",
        "category": "cond-mat"
    },
    {
        "text": "Theory of Underdoped Cuprates: We develop a slave-boson theory for the t-J model at finite doping which\nrespects an SU(2) symmetry -- a symmetry previously known to be important at\nhalf filling. The mean field phase diagram is found to be consistent with the\nphases observed in the cuprate superconductors, which contains d-wave\nsuperconductor, spin gap, strange metal, and Fermi liquid phases. The spin gap\nphase is best understood as the staggered flux phase, which is nevertheless\ntranslationally invariant for physical quantities. The electron spectral\nfunction shows small Fermi pockets at low doping which continuously evolve into\nthe large Fermi surface at high doping concentrations.",
        "category": "cond-mat"
    },
    {
        "text": "Branch-entangled polariton pairs in planar microcavities and photonic\n  wires: A scheme is proposed for the generation of branch-entangled pairs of\nmicrocavity polaritons through spontaneous inter-branch parametric scattering.\nBranch-entanglement is achievable when there are two twin processes, where the\nrole of signal and idler can be exchanged between two different polariton\nbranches. Branch-entanglement of polariton pairs can lead to the emission of\nfrequency-entangled photon pairs out of the microcavity. In planar\nmicrocavities, the necessary phase-matching conditions are fulfilled for\npumping of the upper polariton branch at an arbitrary in-plane wave-vector. The\nimportant role of nonlinear losses due to pair scattering into high-momentum\nexciton states is evaluated. The results show that the lack of protection of\nthe pump polaritons in the upper branch is critical. In photonic wires,\nbranch-entanglement of one-dimensional polaritons is achievable when the pump\nexcites a lower polariton sub-branch at normal incidence, providing protection\nfrom the exciton reservoir.",
        "category": "cond-mat"
    },
    {
        "text": "Quadratic heat capacity and high-field magnetic phases of V5S8: We report the observation of an unexpected quadratic temperature dependence\nof the heat capacity in the vanadium sulphide metal V5S8 at low temperatures\nwhich is independent of applied magnetic field. We find that the behaviour of\nthe heat capacity is consistent with an unconventional phonon spectrum which is\nlinear in wavevector in the c direction but quadratic in the a-b plane,\nindicating a form of geometrical elastic criticality. In the case of V5S8 we\nalso observe an unusual intermediate transition at high magnetic fields between\nthe expected spin-flop and spin-flip transitions. We demonstrate that the\nintermediate field-induced transition is in agreement with a model of two\nsublattices with frustrated inter- and intra-sublattice spin couplings.",
        "category": "cond-mat"
    },
    {
        "text": "Nonclassical rotational inertia for a supersolid under rotation: As proposed by Leggett [4], the supersolidity of a crystal is characterized\nby the Non Classical Rotational Inertia (NCRI) property. Using a model of\nquantum crystal introduced by Josserand, Pomeau and Rica [5], we prove that\nNCRI occurs. This is done by analyzing the ground state of the aforementioned\nmodel, which is related to a sphere packing problem, and then deriving a\ntheoretical formula for the inertia momentum. We infer a lower estimate for the\nNCRI fraction, which is a landmark of supersolidity.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-wave nonreciprocity based on interband magnonic transitions: We theoretically demonstrate linear spin-wave nonreciprocity in a Ni80Fe20\nnanostripe waveguide, based on interband magnonic transitions induced by a\ntime-reversal and spatialinversion symmetry breaking magnetic field. An\nanalytical coupled-mode theory of spin waves, developed to describe the\ntransitions which are accompanied by simultaneous frequency and wavevector\nshifts of the coupled spin waves, is well corroborated by numerical\nsimulations. Our findings could pave the way for the realization of spin-wave\nisolation and the dynamic control of spin-wave propagation in nanoscale\nmagnonic integrated circuits via an applied magnetic field.",
        "category": "cond-mat"
    },
    {
        "text": "An electronic origin of charge order in infinite-layer nickelates: A charge order (CO) with a wavevector\n$\\mathbf{q}\\simeq\\left(\\frac{1}{3},0,0\\right)$ is observed in infinite-layer\nnickelates. Here we use first-principles calculations to demonstrate a\ncharge-transfer-driven CO mechanism in infinite-layer nickelates, which leads\nto a characteristic Ni$^{1+}$-Ni$^{2+}$-Ni$^{1+}$ stripe state. For every three\nNi atoms, due to the presence of near-Fermi-level conduction bands, Hubbard\ninteraction on Ni-$d$ orbitals transfers electrons on one Ni atom to conduction\nbands and leaves electrons on the other two Ni atoms to become more localized.\nWe further derive a low-energy effective model to elucidate that the CO state\narises from a delicate competition between Hubbard interaction on Ni-$d$\norbitals and charge transfer energy between Ni-$d$ orbitals and conduction\nbands. With physically reasonable parameters,\n$\\mathbf{q}=\\left(\\frac{1}{3},0,0\\right)$ CO state is more stable than uniform\nparamagnetic state and usual checkerboard antiferromagnetic state. Our work\nhighlights the multi-band nature of infinite-layer nickelates, which leads to\nsome distinctive correlated properties that are not found in cuprates.",
        "category": "cond-mat"
    },
    {
        "text": "Field-angle-dependent specific heat measurements and gap determination\n  of a heavy fermion superconductor URu2Si2: To identify the superconducting gap structure in URu2Si2 we perform\nfield-angle-dependent specific heat measurements for the two principal\norientations in addition to field rotations, and theoretical analysis based on\nmicroscopic calculations. The Sommerfeld coefficient \\gamma(H)'s in the mixed\nstate exhibit distinctively different field-dependence. This comes from point\nnodes and substantial Pauli paramagnetic effect of URu2Si2. These two features\ncombined give rise to a consistent picture of superconducting properties,\nincluding a possible first order transition of Hc2 at low temperatures.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-splitting in GaAs 2D holes: We present quantitative measurements and calculations of the spin-orbit\ninduced zero-magnetic-field spin-splitting in two-dimensional (2D) hole systems\nin modulation-doped GaAs (311)A quantum wells. The results show that the\nsplitting is large and tunable. In particular, via a combination of back- and\nfront-gate biases, we can tune the splitting while keeping the 2D hole density\nconstant. The data also reveal a surprising result regarding the\nmagnetoresistance (Shubnikov-de Haas) oscillations in a 2D system with\nspin-split energy bands: the frequencies of the oscillations are {\\it not}\nsimply related to the population of the spin-subbands. Next we concentrate on\nthe metallic-like behavior observed in these 2D holes and its relation to\nspin-splitting. The data indicate that the metallic behavior is more pronounced\nwhen two spin-subbands with unequal populations are occupied. Our measurements\nof the magnetoresistance of these 2D hole systems with an in-plane magnetic\nfield corroborate this conclusion: while the system is metallic at zero\nmagnetic field, it turns insulating when one of the spin-subbands is\ndepopulated at high magnetic field.",
        "category": "cond-mat"
    },
    {
        "text": "Generation and detection of mode-locked spin coherence in (In,Ga)As/GaAs\n  quantum dots by laser pulses of long duration: Using optical pulses of variable duration up to 80 ps, we report on spin\ncoherence initialization and its subsequent detection in n-type singly-charged\nquantum dots, subject to a transverse magnetic field, by pump-probe techniques.\nWe demonstrate experimentally and theoretically that the spin coherence\ngeneration and readout efficiencies are determined by the ratio of laser pulse\nduration to spin precession period: An increasing magnetic field suppresses the\nspin coherence signals for a fixed duration of pump and/or probe pulses, and\nthis suppression occurs for smaller fields the longer the pulse duration is.\nThe reason for suppression is the varying spin orientation due to precession\nduring pulse action.",
        "category": "cond-mat"
    },
    {
        "text": "Stretched Non-negative Matrix Factorization: An algorithm is described and tested that carries out a non negative matrix\nfactorization (NMF) ignoring any stretching of the signal along the axis of the\nindependent variable. This extended NMF model is called StretchedNMF.\nVariability in a set of signals due to this stretching is then ignored in the\ndecomposition. This can be used, for example, to study sets of powder\ndiffraction data collected at different temperatures where the materials are\nundergoing thermal expansion. It gives a more meaningful decomposition in this\ncase where the component signals resemble signals from chemical components in\nthe sample. The StretchedNMF model introduces a new variable, the stretching\nfactor, to describe any expansion of the signal. To solve StretchedNMF, we\ndiscretize it and employ Block Coordinate Descent framework algorithms. The\ninitial experimental results indicate that StretchedNMF model outperforms the\nconventional NMF for sets of data with such an expansion. A further enhancement\nto StretchedNMF for the case of powder diffraction data from crystalline\nmaterials called Sparse-StretchedNMF, which makes use of the sparsity of the\npowder diffraction signals, allows correct extractions even for very small\nstretches where StretchedNMF struggles. As well as demonstrating the model\nperformance on simulated PXRD patterns and atomic pair distribution functions\n(PDFs), it also proved successful when applied to real data taken from an in\nsitu chemical reaction experiment.",
        "category": "cond-mat"
    },
    {
        "text": "Optical absorption and carrier multiplication at graphene edges in a\n  magnetic field: We study optical absorption at graphene edges in a transversal magnetic\nfield. The magnetic field bends the trajectories of particle- and hole\nexcitations into antipodal direction which generates a directed current. We\nfind a rather strong amplification of the edge current by impact ionization\nprocesses. More concretely, the primary absorption and the subsequent carrier\nmultiplication is analyzed for a graphene fold and a zigzag edge. We identify\nexact and approximate selection rules and discuss the dependence of the decay\nrates on the initial state.",
        "category": "cond-mat"
    },
    {
        "text": "Magneto-Electric Effect for Multiferroic Thin Film by Monte Carlo\n  Simulation: Magneto-electric effect in a multiferroic heterostructure film, i.e. a\ncoupled ferromagnetic-ferroelectric thin film, has been investigated through\nthe use of the Metropolis algorithm in Monte Carlo simulations. A classical\nHeisenberg model describes the energy stored in the ferromagnetic film, and we\nuse a pseudo-spin model with a transverse Ising Hamiltonian to characterise the\nenergy of electric dipoles in the ferroelectric film. The purpose of this\narticle is to demonstrate the dynamic response of polarisation is driven by an\nexternal magnetic field, when there is a linear magneto-electric coupling at\nthe interface between the ferromagnetic and ferroelectric components.",
        "category": "cond-mat"
    },
    {
        "text": "Giant non-linear susceptibility of hydrogenic donors in silicon and\n  germanium: Implicit summation is a technique for the conversion of sums over\nintermediate states in multiphoton absorption and the high-order susceptibility\nin hydrogen into simple integrals. Here, we derive the equivalent technique for\nhydrogenic impurities in multi-valley semiconductors. While the absorption has\nuseful applications, it is primarily a loss process; conversely, the non-linear\nsusceptibility is a crucial parameter for active photonic devices. For Si:P, we\npredict the hyperpolarizability ranges from $\\chi^{(3)}/n_{\\text{3D}}=2.9 $ to\n$580 \\times 10^{-38}$ $\\text{m}^5/\\text{V}^2$ depending on the frequency, even\nwhile avoiding resonance. Using samples of a reasonable density,\n$n_{\\text{3D}}$, and thickness, $L$, to produce third-harmonic generation at 9\nTHz, a frequency that is difficult to produce with existing solid-state\nsources, we predict that $\\chi^{(3)}$ should exceed that of bulk InSb and\n$\\chi^{(3)}L$ should exceed that of graphene and resonantly enhanced quantum\nwells.",
        "category": "cond-mat"
    },
    {
        "text": "Thermoelectric Effect at Quantum Limit in Two-Dimensional Organic Dirac\n  Fermion System with Zeeman Splitting: The thermoelectric effect in a two-dimensional (2D) massless Dirac fermion\n(DF) system at the quantum limit is discussed to verify the prediction of\nhigh-performance thermopower in an organic conductor \\alpha-(BEDT-TTF)2I3.\nBecause of relatively large Zeeman splitting in \\alpha-(BEDT-TTF)2I3, the\nboundless increase of thermopower at high magnetic fields, predicted without\nthe Zeeman effect, is hardly expected, whereas there appears to be a broad\nlocal maximum. This is characteristic of 2D DF systems with Zeeman splitting\nand is recognized in the previous experiment. In contrast to 3D Dirac/Weyl\nsemimetals with robust gapless features, it might be difficult to realize\nhigh-performance thermopower in real 2D DF systems under high magnetic fields.",
        "category": "cond-mat"
    },
    {
        "text": "Thermodynamic signatures of short-range magnetic correlations in UTe$_2$: The normal-state out of which unconventional superconductivity in UTe$_2$\nemerges is studied in detail using a variety of thermodynamic and transport\nprobes. Clear evidence for a broad Schottky-like anomaly with roughly R ln 2\nentropy around $T^{*} \\approx 12$K is observed in all measured quantities.\nComparison with high magnetic field transport data allows the construction of\nan $H\\text{-}T$ phase diagram resembling that of the ferromagnetic\nsuperconductor URhGe. The low field electronic Gr\\\"uneisen parameter of $T^{*}$\nand that of the metamagnetic transition at $H_m \\approx 35$T are comparable\npointing to a common origin of both phenomena. Enhanced Wilson and Korringa\nratios suggests that the existence of short range ferromagnetic fluctuations\ncannot be ruled out.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical AC study of the critical behavior in Heisenberg spin glasses: We present some numerical results for the Heisenberg spin-glass model with\nGaussian interactions, in a three dimensional cubic lattice. We measure the AC\nsusceptibility as a function of temperature and determine an apparent finite\ntemperature transition which is compatible with the chiral-glass temperature\ntransition for this model. The relaxation time diverges like a power law\n$\\tau\\sim (T-T_c)^{-z\\nu}$ with $T_c=0.19(4)$ and $z\\nu=5.0(5)$. Although our\ndata indicates that the spin-glass transition occurs at the same temperature as\nthe chiral glass transition, we cannot exclude the possibility of a chiral-spin\ncoupling scenario for the lowest frequencies investigated.",
        "category": "cond-mat"
    },
    {
        "text": "Fully spin-polarized nodal loop semimetals in alkaline-metal\n  monochalcogenide monolayers: Topological semimetals in ferromagnetic materials have attracted enormous\nattention due to the potential applications in spintronics. Using the\nfirst-principles density functional theory together with an effective lattice\nmodel, here we present a new family of topological semimetals with a fully\nspin-polarized nodal loop in alkaline-metal monochalcogenide $MX$ ($M$ = Li,\nNa, K, Rb, Cs; $X$ = S, Se, Te) monolayers. The half-metallic ferromagnetism\ncan be established in $MX$ monolayers, in which one nodal loop formed by two\ncrossing bands with the same spin components is found at the Fermi energy. This\nnodal loop half-metal survives even when considering the spin-orbit coupling\nowing to the symmetry protection provided by the $\\mathcal{M}_{z}$ mirror\nplane. The quantum anomalous Hall state and Weyl-like semimetal in this system\ncan be also achieved by rotating the spin from the out-of-plane to the in-plane\ndirection. The $MX$ monolayers hosting rich topological phases thus offer an\nexcellent materials platform for realizing the advanced spintronics concepts.",
        "category": "cond-mat"
    },
    {
        "text": "Heat diode and engine based on quantum Hall edge states: We investigate charge and energy transport in a three-terminal quantum Hall\nconductor. The peculiar properties of chiral propagation along the edges of the\nsample have important consequences on the response to thermal biases. Based on\nthe separation of charge and heat flows, thermoelectric conversion and heat\nrectification can be manipulated by tuning the scattering at gate-modulated\nconstrictions. Chiral motion in a magnetic field allows for a different\nbehaviour of left- and right-moving carriers giving rise to thermal\nrectification by redirecting the heat flows. We propose our system both as an\nefficient heat-to-work converter and as a heat diode.",
        "category": "cond-mat"
    },
    {
        "text": "The length scale measurements of the Fractional quantum Hall state on\n  cylinder: Once the fractional quantum Hall (FQH) state for a finite size system is put\non the surface of a cylinder, the distance between the two ends with open\nboundary conditions can be tuned as varying the aspect ratio $\\gamma$. It\nscales linearly as increasing the system size and therefore has a larger\nadjustable range than that on disk. The previous study of the quasi-hole\ntunneling amplitude on disk in Ref.~\\cite{Zk2011} indicates that the tunneling\namplitudes have a scaling behavior as a function of the tunneling distance and\nthe scaling exponents are related to the scaling dimension and the charge of\nthe transported quasiparticles. However, the scaling behaviors poorly due to\nthe narrow range of the tunneling distance on disk. Here we systematically\nstudy the quasiparticle tunneling amplitudes of the Laughlin state in the\ncylinder geometry which shows a much better scaling behavior. Especially, there\nare some corssover behaviors at two length scales when the two open edges are\nclose to each other. These lengths are also reflected in the bipartite\nentanglement and the electron Green's function as either a singularity or a\ncrossover. These two critical length scales of the edge-edge distance,\n$L_x^{c_1}$ and $L_x^{c_2}$, are found to be related to the dimension reduction\nand back scattering point respectively.",
        "category": "cond-mat"
    },
    {
        "text": "Antiferromagnetic iron based magnetoelectric compounds: The Landau free-energy of a compound that benefits from a linear coupling of\nan electric field and a magnetic field includes a product of the two fields,\none polar and time-even and one axial and time-odd. In ME compounds,\nexpectation values of some atomic magnetic tensors are invariant with respect\nto anti-inversion. An invariance shared by the Dirac monopole (an element of\ncharge allowed in Maxwell's equations that has not been observed) and a\nZeldovich anapole, also known as a Dirac dipole. From the science of materials\nperspective, it has been established that Dirac multipoles contribute to the\ndiffraction of x-rays and neutrons. We identify Dirac monopoles in bulk\nmagnetic properties of iron tellurate (Fe2TeO6) and a spin ladder (SrFe2S2O).\nBoth cited compounds present a simple antiferromagnetic configuration of axial\ndipoles, and their different magnetic crystal classes allow a linear ME effect.\nHowever, the Kerr effect is symmetry allowed in the spin ladder and forbidden\nin iron tellurate. Anapoles are forbidden in iron tellurate and allowed in the\nspin ladder compound, a difference evident in diffraction patterns fully\ninformed by symmetry. More generally, we identify a raft of Dirac multipoles,\nand axial multipoles beyond dipoles, visible in future experiments using\nstandard techniques with beams of neutrons or x-rays tuned in energy to an iron\natomic resonance. ME invariance imposes a phase relationship between nuclear\n(charge) and magnetic contributions to neutron (x-ray) diffraction amplitudes.\nIn consequence, intensities of Bragg spots in an x-ray pattern do not change\nwhen helicity in the primary beam is reversed. A like effect occurs in the\nmagnetic diffraction of polarized neutrons.",
        "category": "cond-mat"
    },
    {
        "text": "Aperiodic crystals and beyond: Crystals are paradigms of ordered structures. While order was once seen as\nsynonymous with lattice periodic arrangements, the discoveries of\nincommensurate crystals and quasicrystals led to a more general perception of\ncrystalline order, encompassing both periodic and aperiodic crystals. The\ncurrent definition of crystals rests on their essentially point-like\ndiffraction. Considering a number of recently investigated toy systems, with\nparticular emphasis on non-crystalline ordered structures, the limits of the\ncurrent definition are explored.",
        "category": "cond-mat"
    },
    {
        "text": "Ultrapure Multilayer Graphene in Bromine Intercalated Graphite: We investigate the optical properties of bromine intercalated highly\norientated pyrolytic graphite (Br-HOPG) and provide a novel interpretation of\nthe data. We observe new absorption features below 620 meV which are absent in\nthe absorption spectrum of graphite. Comparing our results with those of\ntheoretical studies on graphite, single and bilayer graphene as well as recent\noptical studies of multilayer graphene, we conclude that Br-HOPG contains the\nsignatures of ultrapure bilayer, single layer graphene, and graphite. The\nobserved supermetallic conductivity of Br-HOPG is identified with the presence\nof very high mobility (~ 121,000 cm2V-1s-1 at room temperature and at very high\ncarrier density) multilayer graphene components in our sample. This could\nprovide a new avenue for single and multilayer graphene research.",
        "category": "cond-mat"
    },
    {
        "text": "Probing the Lattice Anharmonicity of Superconducting\n  YBa$_2$Cu$_3$O$_{7-\u03b4}$ Via Phonon Harmonics: We examine coherent phonons in a strongly driven sample of optimally-doped\nhigh temperature superconductor YBa$_2$Cu$_3$O$_{7-\\delta}$. We observe a\nnon-linear lattice response of the 4.5\\,THz copper-oxygen vibrational mode at\nhigh excitation densities, evidenced by the observation of the phonon third\nharmonic and indicating the mode is strongly anharmonic. In addition, we\nobserve how high-amplitude phonon vibrations modify the position of the\nelectronic charge transfer resonance. Both of these results have important\nimplications for possible phonon-driven non-equilibrium superconductivity.",
        "category": "cond-mat"
    },
    {
        "text": "Absorption suppression in photonic crystals: We study electromagnetic properties of periodic composite structures, such as\nphotonic crystals, involving lossy components. We show that in many cases a\nproperly designed periodic structure can dramatically suppress the losses\nassociated with the absorptive component, while preserving or even enhancing\nits useful functionality. As an example, we consider magnetic photonic\ncrystals, in which the lossy magnetic component provides nonreciprocal Faraday\nrotation. We show that the electromagnetic losses in the composite structure\ncan be reduced by up to two orders of magnitude, compared to those of the\nuniform magnetic sample made of the same lossy magnetic material. Importantly,\nthe dramatic absorption reduction is not a resonance effect and occurs over a\nbroad frequency range covering a significant portion of photonic frequency\nband.",
        "category": "cond-mat"
    },
    {
        "text": "Electrochemical lithium intercalation in nanosized manganese oxides: X-ray amorphous manganese oxides were prepared by reduction of sodium\npermanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition\nof manganese carbonate at moderate temperature (MnOx-C). TEM showed that these\nmaterials are not amorphous, but nanostructured, with a prominent spinel\nsubstructure in MnOx-C. These materials intercalate lithium with capacities up\nto 200 mAh/g at first cycle (potential window 1.8-4.3 V) and 175 mAh/g at 100th\ncycle. Best performances for MnOx-C are obtained with cobalt doping. Potential\nelectrochemical spectroscopy shows that the initial discharge induces a 2-phase\ntransformation in MnOx-C phases, but not in MnOx-I ones. EXAFS and XANES\nconfirm the participation of manganese in the redox process, with variations in\nlocal structure much smaller than in known long-range crystallized manganese\noxides. X-ray absorption spectroscopy also shows that cobalt in MnOx-C is\ndivalent and does not participate in the electrochemical reaction.",
        "category": "cond-mat"
    },
    {
        "text": "Franck-Condon-Broadened Angle-Resolved Photoemission Spectra Predicted\n  in LaMnO3: The sudden photohole of least energy created in the photoemission process is\na vibrationally excited state of a small polaron. Therefore the photoemission\nspectrum in LaMnO3 is predicted to have multiple Franck-Condon vibrational\nsidebands. This generates an intrinsic line broadening approximately 0.5 eV.\nThe photoemission spectral function has two peaks whose central energies\ndisperse with band width approximately 1.2 eV. Signatures of these phenomena\nare predicted to appear in angle-resolved photoemission spectra.",
        "category": "cond-mat"
    },
    {
        "text": "Uncovering the Dominant Scatterer in Graphene Sheets on SiO2: We have measured the impact of atomic hydrogen adsorption on the electronic\ntransport properties of graphene sheets as a function of hydrogen coverage and\ninitial, pre-hydrogenation field-effect mobility. Our results are compatible\nwith hydrogen adsorbates inducing intervalley mixing by exerting a short-range\nscattering potential. The saturation coverages for different devices are found\nto be proportional to their initial mobility, indicating that the number of\nnative scatterers is proportional to the saturation coverage of hydrogen. By\nextrapolating this proportionality, we show that the field-effect mobility can\nreach $1.5 \\times 10^4$ cm$^2$/V sec in the absence of the hydrogen-adsorbing\nsites. This affinity to hydrogen is the signature of the most dominant type of\nnative scatterers in graphene-based field-effect transistors on SiO$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Controlling dynamical entanglement in a Josephson tunneling junction: We analyze the evolution of an entangled many-body state in a Josephson\ntunneling junction. A N00N state, which is a superposition of two complementary\nFock states, appears in the evolution with sufficient probability only for a\nmoderate many-body interaction on an intermediate time scale. This time scale\nis inversely proportional to the tunneling rate. Interaction between particles\nsupports entanglement: The probability for creating an entangled state decays\nexponentially with the number of non-interacting particles, whereas it decays\nonly like the inverse square root of the number of interacting particles.",
        "category": "cond-mat"
    },
    {
        "text": "Exact thermodynamic limit of short-range correlation functions of the\n  antiferromagnetic $XXZ$-chain at finite temperatures: We evaluate numerically certain multiple integrals representing nearest and\nnext-nearest neighbor correlation functions of the spin-1/2 $XXZ$ Heisenberg\ninfinite chain at finite temperatures.",
        "category": "cond-mat"
    },
    {
        "text": "Spectroscopy Study on NV Sensors in Diamond-based High-pressure Devices: Recently, the negatively charged nitrogen-vacancy (NV) center has emerged as\na robust and versatile quantum sensor in pressurized environments. There are\ntwo popular ways to implement NV sensing in a diamond anvil cell (DAC), which\nis a conventional workhorse in the high-pressure community: create implanted NV\ncenters (INVs) at the diamond anvil tip or immerse NV-enriched nano-diamonds\n(NDs) in the pressure medium. Nonetheless, there are limited studies on\ncomparing the local stress environments experienced by these sensor types as\nwell as their performances as pressure gauges. In this work, by probing the NV\nenergy levels with the optically detected magnetic resonance (ODMR) method, we\nexperimentally reveal a dramatic difference in the partially reconstructed\nstress tensors of INVs and NDs incorporated in the same DAC. Our measurement\nresults agree with computational simulations, concluding that INVs perceive a\nmore non-hydrostatic environment dominated by a uniaxial stress along the DAC\naxis. This provides insights on the suitable choice of NV sensors for specific\npurposes and the stress distribution in a DAC. We further propose some possible\nmethods, such as using NDs and nanopillars, to extend the maximum working\npressure of quantum sensing based on ODMR spectroscopy, since the maximum\nworking pressure could be restricted by non-hydrostaticity of the pressure\nenvironment. Moreover, we explore more sensing applications of the NV center by\nstudying how pressure modifies different aspects of the NV system. We perform a\nphotoluminescence study using both INVs and NDs to determine the pressure\ndependence of the zero-phonon line, which helps developing an all-optical\npressure sensing protocol with the NV center. We also characterize the\nspin-lattice relaxation ($T_1$) time of INVs under pressure to lay a foundation\nfor robust pulsed measurements with NV centers in pressurized environments.",
        "category": "cond-mat"
    },
    {
        "text": "Nonequilibrium hyperuniform states in active turbulence: We demonstrate that the complex spatiotemporal structure in active fluids can\nfeature characteristics of hyperuniformity. Using a hydrodynamic model, we show\nthat the transition from hyperuniformity to non-hyperuniformity and\nanti-hyperuniformity depends on the strength of active forcing and can be\nrelated to features of active turbulence without and with scaling\ncharacteristics of inertial turbulence. Combined with identified signatures of\nLevy walks and non-universal diffusion in these systems, this allows for a\nbiological interpretation and the speculation of non-equilibrium hyperuniform\nstates in active fluids as optimal states with respect to robustness and\nstrategies of evasion and foraging.",
        "category": "cond-mat"
    },
    {
        "text": "Possible observation of phase separation near a quantum phase transition\n  in doubly connected ultrathin superconducting cylinders of aluminum: The kinetic energy of superconducting electrons in an ultrathin, doubly\nconnected superconducting cylinder, determined by the applied flux, increases\nas the cylinder diameter decreases, leading to a destructive regime around\nhalf-flux quanta and a superconductor to normal metal quantum phase transition\n(QPT). Regular step-like features in resistance vs. temperature curves taken at\nfixed flux values were observed near the QPT in ultrathin Al cylinders. It is\nproposed that these features are most likely resulted from a phase separation\nnear the QPT in which normal regions nucleate in a homogeneous superconducting\ncylinder.",
        "category": "cond-mat"
    },
    {
        "text": "Absence of Landau damping in driven three-component Bose-Einstein\n  condensate in optical lattices: We explore the quantum many-body physics of a three-component Bose-Einstein\ncondensate (BEC) in an optical lattices driven by laser fields in $V$ and\n$\\Lambda$ configurations. We obtain exact analytical expressions for the energy\nspectrum and amplitudes of elementary excitations, and discover symmetries\namong them. We demonstrate that the applied laser fields induce a gap in the\notherwise gapless Bogoliubov spectrum. We find that Landau damping of the\ncollective modes above the energy of the gap is carried by laser-induced roton\nmodes and is considerably suppressed compared to the phonon-mediated damping\nendemic to undriven scalar BECs.",
        "category": "cond-mat"
    },
    {
        "text": "Interdisciplinary Discovery of Nanomaterials Based on Convolutional\n  Neural Networks: The material science literature contains up-to-date and comprehensive\nscientific knowledge of materials. However, their content is unstructured and\ndiverse, resulting in a significant gap in providing sufficient information for\nmaterial design and synthesis. To this end, we used natural language processing\n(NLP) and computer vision (CV) techniques based on convolutional neural\nnetworks (CNN) to discover valuable experimental-based information about\nnanomaterials and synthesis methods in energy-material-related publications.\nOur first system, TextMaster, extracts opinions from texts and classifies them\ninto challenges and opportunities, achieving 94% and 92% accuracy,\nrespectively. Our second system, GraphMaster, realizes data extraction of\ntables and figures from publications with 98.3\\% classification accuracy and\n4.3% data extraction mean square error. Our results show that these systems\ncould assess the suitability of materials for a certain application by\nevaluation of synthesis insights and case analysis with detailed references.\nThis work offers a fresh perspective on mining knowledge from scientific\nliterature, providing a wide swatch to accelerate nanomaterial research through\nCNN.",
        "category": "cond-mat"
    },
    {
        "text": "Irreversible effects of memory: The steady state of a Langevin equation with short ranged memory and coloured\nnoise is analyzed. When the fluctuation-dissipation theorem of second kind is\nnot satisfied, the dynamics is irreversible, i.e. detailed balance is violated.\nWe show that the entropy production rate for this system should include the\npower injected by ``memory forces''. With this additional contribution, the\nFluctuation Relation is fairly verified in simulations. Both dynamics with\ninertia and overdamped dynamics yield the same expression for this additional\npower. The role of ``memory forces'' within the fluctuation-dissipation\nrelation of first kind is also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Kinetics of fragmentation and dissociation of two-strand protein\n  filaments: Coarse-grained simulations and experiments: While a significant body of investigations have been focused on the process\nof protein self-assembly, much less is understood about the reverse process of\na filament breaking due to thermal motion into smaller fragments, or\ndepolymerization of subunits from the filament ends. Indirect evidence for\nactin and amyloid filament fragmentation has been reported, although the\nphenomenon has never been directly observed either experimentally or in\nsimulations. Here we report the direct observation of filament depolymerization\nand breakup in a minimal, calibrated model of coarse-grained molecular\nsimulation. We quantify the orders of magnitude by which the depolymerization\nrate from the filament ends $k_\\mathrm{off}$ is larger than fragmentation rate\n$k_{-}$ and establish the law $k_\\mathrm{off}/k_- = \\exp [( \\varepsilon_\\| -\n\\varepsilon_\\bot) / k_\\mathrm{B}T ] = \\exp [0.5 \\varepsilon / k_\\mathrm{B}T ]$,\nwhich accounts for the topology and energy of bonds holding the filament\ntogether. This mechanism and the order-of-magnitude predictions are well\nsupported by direct experimental measurements of depolymerization of insulin\namyloid filaments.",
        "category": "cond-mat"
    },
    {
        "text": "Efficient Generation of Grids and Traversal Graphs in Compositional\n  Spaces towards Exploration and Path Planning Exemplified in Materials: Many disciplines of science and engineering deal with problems related to\ncompositions, ranging from chemical compositions in materials science to\nportfolio compositions in economics. They exist in non-Euclidean simplex\nspaces, causing many standard tools to be incorrect or inefficient, which is\nsignificant in combinatorically or structurally challenging spaces exemplified\nby Compositionally Complex Materials (CCMs) and Functionally Graded Materials\n(FGMs). Here, we explore them conceptually in terms of problem spaces and\nquantitatively in terms of computational feasibility.\n  This work implements several essential methods specific to the compositional\n(simplex) spaces through a high-performance open-source library nimplex. Most\nsignificantly, we derive and implement an algorithm for constructing a novel\nn-dimensional simplex graph data structure, which contains all discretized\ncompositions and all possible neighbor-to-neighbor transitions as pointer\narrays. Critically, no distance or neighborhood calculations are performed,\ninstead leveraging pure combinatorics and the ordering in procedurally\ngenerated simplex grids, keeping the algorithm $\\mathcal{O}(N)$, so that graphs\nwith billions of transitions take seconds to construct on a laptop.\nFurthermore, we demonstrate how such graph representations can be combined to\nexpress path-planning problem spaces and to incorporate prior knowledge while\nkeeping the problem space homogeneous. This allows for efficient deployment of\nexisting high-performance gradient descent, graph traversal search, and other\npath optimization algorithms.",
        "category": "cond-mat"
    },
    {
        "text": "Charge-stripe order in the electronic ferroelectric LuFe2O4: The structural features of the charge ordering states in LuFe2O4 are\ncharacterized by in-situ cooling TEM observations from 300K down to 20K. Two\ndistinctive structural modulations, a major q1= (1/3, 1/3, 2) and a weak\nq2=q1/10 + (0, 0, 3/2), have been well determined at the temperature of 20K.\nSystematic analysis demonstrates that the charges at low temperatures are well\ncrystallized in a charge stripe phase, in which the charge density wave\nbehaviors in a non-sinusoidal fashion resulting in elemental electric dipoles\nfor ferroelectricity. It is also noted that the charge ordering and\nferroelectric domains often change markedly with lowering temperatures and\nyields a rich variety of structural phenomena.",
        "category": "cond-mat"
    },
    {
        "text": "Doping-dependent energy scale of the low-energy band renormalization in\n  (Bi,Pb)2(Sr,La)2CuO6+d: The nodal band-dispersion in (Bi,Pb)2(Sr,La)2CuO6+d (Bi2201) is investigated\nover a wide range of doping by using 7-eV laser-based angle-resolved\nphotoemission spectroscopy. We find that the low-energy band renormalization\n(\"kink\"), recently discovered in Bi2Sr2CaCu2O8+d (Bi2212), also occurs in\nBi2201, but at a binding energy around half that in Bi2212, implying its\nscaling to Tc. Surprisingly the coupling-energy dramatically increases with a\ndecrease of carrier concentration, showing a sharp enhancement across the\noptimal doping. This strongly contrasts to other mode-couplings at higher\nbinding-energies (~20, ~40, and ~70 meV) with almost no doping variation in\nenergy scale. These nontrivial properties of the low-energy kink (material- and\ndoping-dependence of the coupling-energy) demonstrate the significant\ncorrelation among the mode-coupling, the Tc, and the strong electron\ncorrelation.",
        "category": "cond-mat"
    },
    {
        "text": "Graph-based analysis of nonreciprocity in coupled-mode systems: In this work we derive the general conditions for obtaining nonreciprocity in\nmulti-mode parametrically-coupled systems. The results can be applied to a\nbroad variety of optical, microwave, and hybrid systems including recent\nelectro- and opto-mechanical devices. In deriving these results, we use a\ngraph-based methodology to derive the scattering matrix. This approach\nnaturally expresses the terms in the scattering coefficients as separate graphs\ncorresponding to distinct coupling paths between modes such that it is evident\nthat nonreciprocity arises as a consequence of multi-path interference and\ndissipation in key ancillary modes. These concepts facilitate the construction\nof new devices in which several other characteristics might also be\nsimultaneously optimized. As an example, we synthesize a novel three-mode\nunilateral amplifier design by use of graphs. Finally, we analyze the isolation\ngenerated in a common parametric multi-mode system, the DC-SQUID.",
        "category": "cond-mat"
    },
    {
        "text": "Inherently high valley polarizations of momentum-forbidden dark excitons\n  in transition-metal dichalcogenide monolayers: High degree of valley polarization of optically active excitons in\ntransition-metal dichalcogenide monolayers (TMD-MLs) is vital in valley-based\nphotonic applications but known to be likely spoiled by the intrinsic\nelectron-hole exchange interactions. In this study, we present a theoretical\ninvestigation of the valley and optical properties of finite-momentum dark\nexcitons in WSe$_2$-MLs by solving the density-functional-theory(DFT)-based\nBethe-Salpeter equation (BSE) under the guidance of symmetry analysis. %We\nreveal that, in general, finite-momentum excitons are actually well immune from\nthe exchange-induced valley depolarization, except for those with specific\nexciton momenta coincident with the $3\\sigma_v$ and $3C_2'$ symmetries in the\n$D_{3h}$ point group of TMD-MLs. We reveal that, unlike the bright exciton\ninevitably subjected to electron-hole exchange interaction, inter-valley\nfinite-momentum dark excitons in WSe$_2$-MLs are well immune from the\nexchange-induced valley depolarization and inherently highly valley-polarized\nunder the enforcement of the crystal symmetries. More importantly, the superior\nvalley polarizations of the inter-valley dark excitons in WSe$_2$-MLs are shown\nalmost fully transferable to the optical polarization in the phonon-assisted\nphoto-luminescences because of the native suppression of exchange-induced\ndepolarization in the second-order optical processes. The analysis of\nphonon-assisted photo-luminescences accounts for the recently observed\nbrightness, high degree of optical polarization and long lifetime of the\ninter-valley dark exciton states in tungsten-based TMD-MLs.",
        "category": "cond-mat"
    },
    {
        "text": "Growth diagram and magnetic properties of hexagonal LuFe$_2$O$_4$ thin\n  films: A growth diagram of Lu-Fe-O compounds on MgO (111) substrates using pulsed\nlaser deposition is constructed based on extensive growth experiments.\n  The LuFe$_2$O$_4$ phase can only be grown in a small range of temperature and\nO$_2$ pressure conditions.\n  An understanding of the growth mechanism of Lu-Fe-O compound films is offered\nin terms of the thermochemistry at the surface.\n  Superparamagnetism is observed in LuFe$_2$O$_4$ film and is explained in\nterms of the effect of the impurity h-LuFeO$_3$ phase and structural defects .",
        "category": "cond-mat"
    },
    {
        "text": "Hyper-Raman scattering analysis of the vibrations in vitreous boron\n  oxide: Hyper-Raman scattering has been measured on vitreous boron oxide,\n$v-$B$_2$O$_3$. This spectroscopy, complemented with Raman scattering and\ninfrared absorption, reveals the full set of vibrations that can be observed\nwith light. A mode analysis is performed based on the local D$_{3h}$ symmetry\nof BO$_3$ triangles and B$_3$O$_3$ boroxol rings. The results show that in\n$v-$B$_2$O$_3$ the main spectral components can be succesfully assigned using\nthis relatively simple model. In particular, it can be shown that the\nhyper-Raman boson peak arises from external modes that correspond mainly to\nlibrational motions of rigid boroxol rings.",
        "category": "cond-mat"
    },
    {
        "text": "Phonon Dispersion Relationship and Oxygen Isotope Effect in\n  Superconductor LaFeAsO: In this paper we calculate ab initially the phonon dispersion relationship of\nthe superconductor LaFeAsO and investigate a main property in the\nsuperconductor, the oxygen isotope effect. Based on this phonon dispersion\nrelationship, we find the fact that an important reason of the oxygen isotope\neffect is connected with the phonon. This result agrees well with the\nexperimental data where the power index of the oxygen isotope effect in the\nsuperconductor LaFeAsO is small.",
        "category": "cond-mat"
    },
    {
        "text": "Real space mapping of topological invariants using artificial neural\n  networks: Topological invariants allow to characterize Hamiltonians, predicting the\nexistence of topologically protected in-gap modes. Those invariants can be\ncomputed by tracing the evolution of the occupied wavefunctions under twisted\nboundary conditions. However, those procedures do not allow to calculate a\ntopological invariant by evaluating the system locally, and thus require\ninformation about the wavefunctions in the whole system. Here we show that\nartificial neural networks can be trained to identify the topological order by\nevaluating a local projection of the density matrix. We demonstrate this for\ntwo different models, a 1-D topological superconductor and a 2-D quantum\nanomalous Hall state, both with spatially modulated parameters. Our neural\nnetwork correctly identifies the different topological domains in real space,\npredicting the location of in-gap states. By combining a neural network with a\ncalculation of the electronic states that uses the Kernel Polynomial Method, we\nshow that the local evaluation of the invariant can be carried out by\nevaluating a local quantity, in particular for systems without translational\nsymmetry consisting of tens of thousands of atoms. Our results show that\nsupervised learning is an efficient methodology to characterize the local\ntopology of a system.",
        "category": "cond-mat"
    },
    {
        "text": "Detection of the BCS transition of a trapped Fermi Gas: We investigate theoretically the properties of a trapped gas of fermionic\natoms in both the normal and the superfluid phases. Our analysis, which\naccounts for the shell structure of the normal phase spectrum, identifies two\nobservables which are sensitive to the presence of the superfluid: the response\nof the gas to a modulation of the trapping frequency, and the heat capacity.\nOur results are discussed in the context of experiments on trapped Fermi gases.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum interferences in quasicrystals: Contributions of quantum interference effects occuring in quasicrystals are\nemphasized. First conversely to metallic systems, quasiperiodic ones are shown\nto enclose original alterations of their conductive properties while\ndowngrading long range order. Besides, origins of localization mechanisms are\noutlined within the context of the original metal-insulator transition (MIT)\nfound in these materials.",
        "category": "cond-mat"
    },
    {
        "text": "Non-Hermitian quasicrystal in dimerized lattices: Non-Hermitian quasicrystals possess PT and metal-insulator transitions\ninduced by gain and loss or nonreciprocal effects. In this work, we uncover the\nnature of localization transitions in a generalized Aubry-Andre-Harper model\nwith dimerized hopping amplitudes and complex onsite potential. By\ninvestigating the spectrum, adjacent gap ratios and inverse participation\nratios, we find an extended phase, a localized phase and a mobility edge phase,\nwhich are originated from the interplay between hopping dimerizations and\nnon-Hermitian onsite potential. The lower and upper bounds of the mobility edge\nare further characterized by a pair of topological winding numbers, which\nundergo quantized jumps at the boundaries between different phases. Our\ndiscoveries thus unveil the richness of topological and transport phenomena in\ndimerized non-Hermitian quasicrystals.",
        "category": "cond-mat"
    },
    {
        "text": "Optical and transport properties of low-dimensional semiconductor\n  nanostructures: The interpretation of the electronic kinetic processes in the quantum zero\ndimensional nanostructures is considered. The main mechanism of the processes\nis supposed to be the interaction of electrons with the optical phonons. An\nemphasis is put on the recently measured effect of the long-time\nphotoluminescence of quantum dot samples, which is observed to occur after an\nillumination of the sample by a laser pulse. In addition to this, an attention\nis devoted to the possible origin of the optical effect of the blinking\n(intermittence) of the optical emission of certain quantum dot samples under a\npermanent optical excitation, and to another similar effect.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Degenerate Fermi Gas with Spin-orbit Coupling and Crossed Zeeman\n  Fields: We study quantum degenerate ultra-cold Fermi gases in the presence of\nartificial spin-orbit coupling and crossed Zeeman fields. We emphasize the case\nwhere parity is violated in the excitation spectrum and compare it with the\nsimpler situation where parity is preserved. We investigate in detail\nspectroscopic properties such as the excitation spectrum, the spectral\nfunction, momentum distribution and density of states for the cases where\nparity is preserved or violated. Similarly, we show that thermodynamic\nproperties such as pressure, chemical potential, entropy, specific heat,\nisothermal compressibility and induced spin polarization become anisotropic as\na function of Zeeman field components, when parity is violated. Lastly, we\ndiscuss the effects of interactions and present results for the pairing\ntemperature as the precursor for the transition to a superfluid state. In\nparticular, we find that the pairing temperature is dramatically reduced in the\nweak interaction regime as parity violation gets stronger, and that the\nmomentum dependence of the order parameter for superfluidity violates parity\nwhen crossed Zeeman fields are present for finite spin-orbit coupling.",
        "category": "cond-mat"
    },
    {
        "text": "Orbital order in degenerate Hubbard models : A variational study: We use the Gutzwiller variational many-body theory to investigate the\nstability of orbitally ordered states in a two-band Hubbard-model without spin\ndegrees of freedom. Our results differ significantly from earlier Hartree-Fock\ncalculations for this model. The Hartree-Fock phase diagram displays a large\nvariety of orbital orders. In contrast, in the Gutzwiller approach orbital\norder only appears for densities in a narrow region around half filling.",
        "category": "cond-mat"
    },
    {
        "text": "The Bose gas beyond mean field: We study a homogeneous Bose gas with purely repulsive forces. Using the Kac\nscaling of the binary potential we derive analytically the form of the\nthermodynamic functions of the gas for small but finite values of the scaling\nparameter in the low density regime. In this way we determine dominant\ncorrections to the mean-field theory. It turns out that repulsive forces\nincrease the pressure at fixed density and decrease the density at given\nchemical potential (the temperature is kept constant). They also flatten the\nBose momentum distribution. However, the present analysis cannot be extended to\nthe region where the mean-field theory predicts the appearence of condensate.",
        "category": "cond-mat"
    },
    {
        "text": "Multiferroic Decorated Fe2O3 Monolayer Predicted from First Principles: Two-dimensional (2D) multiferroics exhibit cross-control capacity between\nmagnetic and electric responses in reduced spatial domain, making them well\nsuited for next-generation nanoscale devices; however, progress has been slow\nin developing materials with required characteristic properties. Here we\nidentify by first-principles calculations robust 2D multiferroic behaviors in\ndecorated Fe2O3 monolayer, showcasing N@Fe2O3 as a prototypical case, where\nferroelectricity and ferromagnetism stem from the same origin, namely Fe\nd-orbit splitting induced by the Jahn-Teller distortion and associated crystal\nfield changes. The resulting ferromagnetic and ferroelectric polarization can\nbe effectively reversed and regulated by applied electric field or strain,\noffering efficient functionality. These findings establish strong materials\nphenomena and elucidate underlying physics mechanism in a family of truly 2D\nmultiferroics that are highly promising for advanced device applications.",
        "category": "cond-mat"
    },
    {
        "text": "SiQAD: A Design and Simulation Tool for Atomic Silicon Quantum Dot\n  Circuits: This paper introduces SiQAD, a computer-aided design tool enabling the rapid\ndesign and simulation of atomic silicon dangling bond quantum dot patterns\ncapable of computational logic. Several simulation tools are included, each\nable to inform the designer on various aspects of their designs: a ground-state\nelectron configuration finder, a non-equilibrium electron dynamics simulator,\nand an electric potential landscape solver with clocking electrode support.\nSimulations have been compared against past experimental results to inform the\nelectron population estimation and dynamic behavior. New logic gates suitable\nfor this platform have been designed and simulated, and a clocked wire has been\ndemonstrated. This work paves the way for the exploration of the vast and\nfertile design space of atomic silicon dangling bond quantum dot circuits.",
        "category": "cond-mat"
    },
    {
        "text": "Electronic Structure of Chromium Trihalides beyond Density Functional\n  Theory: We explore the electronic band structure of free standing monolayers of\nchromium trihalides, CrX\\textsubscript{3}{, X= Cl, Br, I}, within an advanced\n\\emph{ab-initio} theoretical approach based in the use of Green's function\nfunctionals. We compare the local density approximation with the quasi-particle\nself-consistent \\emph{GW} approximation (QS\\emph{GW}) and its self-consistent\nextension (QS$G\\widehat{W}$) by solving the particle-hole ladder Bethe-Salpeter\nequations to improve the effective interaction \\emph{W}. We show that at all\nlevels of theory, the valence band consistently changes shape in the sequence\nCl{\\textrightarrow}Br{\\textrightarrow}I, and the valence band maximum shifts\nfrom the M point to the $\\Gamma$ point. However, the details of the transition,\nthe one-particle bandgap, and the eigenfunctions change considerably going up\nthe ladder to higher levels of theory. The eigenfunctions become more\ndirectional, and at the M point there is a strong anisotropy in the effective\nmass. Also the dynamic and momentum dependent self energy shows that\nQS$G\\widehat{W}$ adds to the localization of the systems in comparison to the\nQS\\emph{GW} thereby leading to a narrower band and reduced amount of halogens\nin the valence band manifold.",
        "category": "cond-mat"
    },
    {
        "text": "Bayesian Optimization in Materials Science: A Survey: Bayesian optimization is used in many areas of AI for the optimization of\nblack-box processes and has achieved impressive improvements of the state of\nthe art for a lot of applications. It intelligently explores large and complex\ndesign spaces while minimizing the number of evaluations of the expensive\nunderlying process to be optimized. Materials science considers the problem of\noptimizing materials' properties given a large design space that defines how to\nsynthesize or process them, with evaluations requiring expensive experiments or\nsimulations -- a very similar setting. While Bayesian optimization is also a\npopular approach to tackle such problems, there is almost no overlap between\nthe two communities that are investigating the same concepts. We present a\nsurvey of Bayesian optimization approaches in materials science to increase\ncross-fertilization and avoid duplication of work. We highlight common\nchallenges and opportunities for joint research efforts.",
        "category": "cond-mat"
    },
    {
        "text": "Mixtures of Bose Gases Confined in a Ring Potential: The rotational properties of a mixture of two distinguishable Bose gases that\nare confined in a ring potential provide novel physical effects that we\ndemonstrate in this study. Persistent currents are shown to be stable for a\nrange of the population imbalance between the two components at low angular\nmomentum. At higher values of the angular momentum, even small admixtures of a\nsecond species of atoms make the persistent currents highly fragile.",
        "category": "cond-mat"
    },
    {
        "text": "Phase ordering and roughening on growing films: We study the interplay between surface roughening and phase separation during\nthe growth of binary films. Already in 1+1 dimension, we find a variety of\ndifferent scaling behaviors depending on how the two phenomena are coupled. In\nthe most interesting case, related to the advection of a passive scalar in a\nvelocity field, nontrivial scaling exponents are obtained in simulations.",
        "category": "cond-mat"
    },
    {
        "text": "A ferroelectric problem beyond the conventional scaling law: Ferroelectric (FE) size effects against the scaling law were reported\nrecently in ultrathin group-IV monochalcogenides, and extrinsic effects (e.g.\ndefects and lattice strains) were often resorted to. Via first-principles based\nfinite-temperature ($T$) simulations, we reveal that these abnormalities are\nintrinsic to their unusual symmetry breaking from bulk to thin film. Changes of\nthe electronic structures result in different order parameters characterizing\nthe FE phase transition in bulk and in thin films, and invalidation of the\nscaling law. Beyond the scaling law $T_{\\text{c}}$ limit, this mechanism can\nhelp predicting materials promising for room-$T$ ultrathin FE devices of broad\ninterest.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-Imbalance and Magnetoresistance in\n  Ferromagnet/Superconductor/Ferromagnet Double Tunnel Junctions: We theoretically study the spin-dependent transport in a ferromagnet/super-\nconductor/ferromagnet double tunnel junction. The tunneling current in the\nantiferromagnetic alignment of the magnetizations gives rise to a spin\nimbalance in the superconductor. The resulting nonequilibrium spin density\nstrongly suppresses the superconductivity with increase of bias voltage and\ndestroys it at a critical voltage Vc. The results provide a new method not only\nfor measuring the spin polarization of ferromagnets but also for controlling\nsuperconductivity and tunnel magnetoresistance (TMR) by applying the bias\nvoltage.",
        "category": "cond-mat"
    },
    {
        "text": "Entropy barriers and accelerated relaxation under resetting: The zero-temperature limit of the backgammon model under resetting is\nstudied. The model is a balls-in-boxes model whose relaxation dynamics is\ngoverned by the density of boxes containing just one particle. As these boxes\nbecome rare at large times, the model presents an entropy barrier. As a\npreliminary step, a related model with faster relaxation, known to be mapped to\na symmetric random walk, is studied by mapping recent results on diffusion with\nresetting onto the balls-in-boxes problem. Diffusion with an absorbing target\nat the origin (and diffusion constant equal to one), stochastically reset to\nthe unit position, is a continuum approximation to the dynamics of the\nballs-in-boxes model, with resetting to a configuration maximising the number\nof boxes containing just one ball. In the limit of a large system, the\nrelaxation time of the balls-in-boxes model under resetting is finite. The\nbackgammon model subject to a constant resetting rate is then studied using an\nadiabatic approximation.",
        "category": "cond-mat"
    },
    {
        "text": "Ettingshausen Effect around Landau Level Filling Factor nu=3 Studied by\n  Dynamic Nuclear Polarization: Spin current perpendicular to the electric current is investigated around\nLandau level filling factor $\\nu=3$ in a GaAs/AlGaAs two-dimensional electron\nsystem. Measurements of dynamic nuclear polarization in the vicinity of the\nedge of a specially designed Hall bar sample indicate that the direction of the\nspin current with respect to the Hall electric field reverses its polarity at\n$\\nu=3$, where the dissipative current carried by holes in the spin up Landau\nlevel is replaced with that by electrons in the spin down Landau level.",
        "category": "cond-mat"
    },
    {
        "text": "Mechanics of freely-suspended ultrathin layered materials: The study of atomically thin two-dimensional materials is a young and rapidly\ngrowing field. In the past years, a great advance in the study of the\nremarkable electrical and optical properties of 2D materials fabricated by\nexfoliation of bulk layered materials has been achieved. Due to the\nextraordinary mechanical properties of these atomically thin materials, they\nalso hold a great promise for future applications such as flexible electronics.\nFor example, this family of materials can sustain very large deformations\nwithout breaking. Due to the combination of small dimensions, high Young's\nmodulus and high crystallinity of 2D materials, they have attracted the\nattention of the field of nanomechanical systems as high frequency and high\nquality factor resonators. In this article, we review experiments on static and\ndynamic response of 2D materials. We provide an overview and comparison of the\nmechanics of different materials, and highlight the unique properties of these\nthin crystalline layers. We conclude with an outlook of the mechanics of 2D\nmaterials and future research directions such as the coupling of the mechanical\ndeformation to their electronic structure.",
        "category": "cond-mat"
    },
    {
        "text": "Photovoltage Dynamics of the Hydroxylated Si(111) Surface Investigated\n  by Ultrafast Electron Diffraction: We present a novel method to measure transient photovoltage at nanointerfaces\nusing ultrafast electron diffraction. In particular, we report our results on\nthe photoinduced electronic excitations and their ensuing relaxations in a\nhydroxyl-terminated silicon surface, a standard substrate for fabricating\nmolecular electronics interfaces. The transient surface voltage is determined\nby observing Coulomb refraction changes induced by the modified space-charge\nbarrier within a selectively probed volume by femtosecond electron pulses. The\nresults are in agreement with ultrafast photoemission studies of surface state\ncharging, suggesting a charge relaxation mechanism closely coupled to the\ncarrier dynamics near the surface that can be described by a drift-diffusion\nmodel. This study demonstrates a newly implemented ultrafast diffraction method\nfor investigating interfacial processes, with both charge and structure\nresolution.",
        "category": "cond-mat"
    },
    {
        "text": "Non-equilibrium dynamic critical scaling of the quantum Ising chain: We solve for the time-dependent finite-size scaling functions of the 1D\ntransverse-field Ising chain during a linear-in-time ramp of the field through\nthe quantum critical point. We then simulate Mott-insulating bosons in a tilted\npotential, an experimentally-studied system in the same equilibrium\nuniversality class, and demonstrate that universality holds for the dynamics as\nwell. We find qualitatively athermal features of the scaling functions, such as\nnegative spin correlations, and show that they should be robustly observable\nwithin present cold atom experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Pair correlations of a spin-imbalanced Fermi gas on two-leg ladders: We study the pair correlations of a spin-imbalanced two-leg ladder with\nattractive interactions, using the density matrix renormalization group method\n(DMRG). We identify regions in the phase diagram spanned by the chemical\npotential and the magnetic field that can harbor\nFulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like physics. Results for the pair\nstructure factor, exhibiting multiple pairing wave-vectors, substantiate the\npresence of FFLO-like correlations. We further discuss phase separation\nscenarios induced by a harmonic trap, which differ from the case of isolated\nchains.",
        "category": "cond-mat"
    },
    {
        "text": "Spontaneous phase coordination and fluid pumping in model ciliary\n  carpets: Ciliated tissues such as in the mammalian lungs, brains, and reproductive\ntracts, are specialized to pump fluid. They generate flows by the collective\nactivity of hundreds of thousands of individual cilia that beat in a striking\nmetachronal wave pattern. Despite progress in analyzing cilia coordination, a\ngeneral theory that links coordination and fluid pumping in the limit of large\narrays of cilia remains lacking. Here, we conduct in-silico experiments with\nthousands of hydrodynamically-interacting cilia, and we develop a continuum\ntheory in the limit of infinitely-many independently beating cilia by combining\ntools from active matter and classical Stokes flow. We find, in both\nsimulations and theory, that isotropic and synchronized ciliary states are\nunstable. Traveling waves emerge regardless of initial conditions, but the\ncharacteristics of the wave and net flows depend on cilia and tissue\nproperties. That is, metachronal phase coordination is a stable global\nattractor in large ciliary carpets, even under finite perturbations to cilia\nand tissue properties. These results support the notion that functional\nspecificity of ciliated tissues is interlaced with the tissue architecture and\ncilia beat kinematics and open up the prospect of establishing\nstructure-to-function maps from cilium-level beat to tissue-level coordination\nand fluid pumping.",
        "category": "cond-mat"
    },
    {
        "text": "Large-scale Atomistic Simulation of Quantum Effects in SrTiO$_3$ from\n  First Principles: Quantum effects of lattice vibration play a major role in many physical\nproperties of condensed matter systems, including thermal properties such as\nspecific heat, structural phase transition, as well as phenomena such as\nquantum crystal and quantum paraelectricity that are closely related to\nzero-point fluctuations. However, realizing atomistic simulations for realistic\nmaterials with a fully quantum-mechanical description remains a great\nchallenge. Here, we propose a first-principle strategy for large scale\nMolecular Dynamics simulation, where high accuracy force field obtained by\nDeep-Potential (DP) is combined with Quantum Thermal Bath (QTB) method to\naccount for quantum effects. We demonstrate the power of this DP+QTB method\nusing the archetypal example SrTiO$_3$, which exhibits several phenomena\ninduced by quantum fluctuations, such as the suppressed structure phase\ntransition temperature, the quantum paraelectric ground state at low\ntemperature and the quantum critical behavior $1/T^2$ law of dielectric\nconstant. Our DP+QTB strategy is efficient in simulating large scale system,\nand is first principle. More importantly, quantum effects of other systems\ncould also be investigated as long as corresponding DP model is trained. This\nstrategy would greatly enrich our vision and means to study quantum behavior of\ncondensed matter physics.",
        "category": "cond-mat"
    },
    {
        "text": "Symbiotic Optimization of the Nanolithography and RF-Plasma Etching for\n  Fabricating High-Quality Light-Sensitive Superconductors on the 50 nm Scale: We present results of a fabrication-process development for the lithographic\npattern transfer into the sub-100nm range by combining electron-beam\nlithography and reactive dry etching to obtain high quality niobium-based\nlight-sensitive superconducting devices. To achieve this spatial resolution, we\nsystematically investigated the stability of the positive organic etching masks\nZEP 520A and PMMA 950k in different properly operated fluoride based plasma\ndischarges. The chemically more robust ZEP 520A was used for defining the\nnanoscaled superconductors during the dry plasma etching. Our etching recipe is\nappropriate for a precisely controlled removal of a number of transition\nmetals, their nitrides and a number of lithographic resists. Our process\nyielded lightsensitive superconducting devices made from NbN with smallest\nplanar lateral dimensions of about 50nm with a critical temperature Tc(0) of\nabout 13K , which is close to the transition temperature of the unstructured\nthin film. Our ultra-narrow current paths are able to permanently carry\nbias-currents up to 60% of the theoretical de-pairing current-limit.",
        "category": "cond-mat"
    },
    {
        "text": "Photon correlation spectroscopy on a single quantum dot embedded in a\n  nanowire: We have observed strong photoluminescence from a single CdSe quantum dot\nembedded in a ZnSe nanowire. Exciton, biexciton and charged exciton lines have\nbeen identified unambiguously using photon correlation spectroscopy. This\ntechnique has provided a detailed picture of the dynamics of this new system.\nThis type of semi conducting quantum dot turns out to be a very efficient\nsingle photon source in the visible. Its particular growth technique opens new\npossibilities as compared to the usual self-asssembled quantum dots.",
        "category": "cond-mat"
    },
    {
        "text": "Engineering Nanowire n-MOSFETs at Lg < 8 nm: As metal-oxide-semiconductor field-effect transistors (MOSFET) channel\nlengths (Lg) are scaled to lengths shorter than Lg<8 nm source-drain tunneling\nstarts to become a major performance limiting factor. In this scenario a\nheavier transport mass can be used to limit source-drain (S-D) tunneling.\nTaking InAs and Si as examples, it is shown that different heavier transport\nmasses can be engineered using strain and crystal orientation engineering.\nFull-band extended device atomistic quantum transport simulations are performed\nfor nanowire MOSFETs at Lg<8 nm in both ballistic and incoherent scattering\nregimes. In conclusion, a heavier transport mass can indeed be advantageous in\nimproving ON state currents in ultra scaled nanowire MOSFETs.",
        "category": "cond-mat"
    },
    {
        "text": "Machine Learning Unifies the Modelling of Materials and Molecules: Determining the stability of molecules and condensed phases is the\ncornerstone of atomistic modelling, underpinning our understanding of chemical\nand materials properties and transformations. Here we show that a machine\nlearning model, based on a local description of chemical environments and\nBayesian statistical learning, provides a unified framework to predict\natomic-scale properties. It captures the quantum mechanical effects governing\nthe complex surface reconstructions of silicon, predicts the stability of\ndifferent classes of molecules with chemical accuracy, and distinguishes active\nand inactive protein ligands with more than 99% reliability. The universality\nand the systematic nature of our framework provides new insight into the\npotential energy surface of materials and molecules.",
        "category": "cond-mat"
    },
    {
        "text": "Phase of phonon-induced resistance oscillations in a high-mobility\n  two-dimensional electron gas: We report on experimental studies of magnetoresistance oscillations that\noriginate from the resonant interaction of two-dimensional electrons with\nthermal transverse-acoustic phonons in very high-mobility GaAs/AlGaAs quantum\nwells. We find that the oscillation maxima consistently occur when a frequency\nof a phonon with twice the Fermi momentum exceeds an integer multiple of the\ncyclotron frequency. This observation is in contrast to to all previous\nexperiments associating resistance maxima with magnetophonon resonance and its\nharmonics. Our experimentally obtained resonant condition is in excellent\nquantitative agreement with recent theoretical proposals.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic models on various topologies: A brief review is given on the study of the thermodynamic properties of spin\nmodels defined on different topologies like small-world, scale-free networks,\nrandom graphs and regular and random lattices. Ising, Potts and Blume-Capel\nmodels are considered. They are defined on complex lattices comprising\nAppolonian, Barab\\'asi-Albert, Voronoi-Delauny and small-world networks. The\nmain emphasis is given on the corresponding phase transitions, transition\ntemperatures, critical exponents and universality, compared to those obtained\nby the same models on regular Bravais lattices.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Monte Carlo study of ultracold gases (PhD thesis): This Dissertation presents results of a thorough study of ultracold bosonic\nand fermionic gases in three-dimensional and quasi-one-dimensional systems.\nAlthough the analyses are carried out within various theoretical frameworks\n(Gross-Pitaevskii, Bethe ansatz, local density approximation, etc.) the main\ntool of the study is the Quantum Monte Carlo method in different modifications\n(variational Monte Carlo, diffusion Monte Carlo, fixed-node Monte Carlo\nmethods). We benchmark our Monte Carlo calculations by recovering known\nanalytical results (perturbative theories in dilute limits, exactly solvable\nmodels, etc.) and extend calculations to regimes, where the results are so far\nunknown. In particular we calculate the equation of state and correlation\nfunctions for gases in various geometries and with various interatomic\ninteractions.",
        "category": "cond-mat"
    },
    {
        "text": "Anomalous Hall effect in van der Waals bonded ferromagnet\n  Fe$_{3-x}$GeTe$_2$: We report anomalous Hall effect (AHE) in single crystals of\nquasi-two-dimensional Fe$_{3-x}$GeTe$_2$ ($x \\approx 0.36$) ferromagnet grown\nby the flux method which induces defects on Fe site and bad metallic\nresistivity. Fe K-edge x-ray absorption spectroscopy was measured to provide\ninformation on local atomic environment in such crystals. The dc and ac\nmagnetic susceptibility measurements indicate a second-stage transition below\n119 K in addition to the paramagnetic to ferromagnetic transition at 153 K. A\nlinear scaling behavior between the modified anomalous Hall resistivity\n$\\rho_{xy}/\\mu_0H_{eff}$ and longitudinal resistivity\n$\\rho_{xx}^2M/\\mu_0H_{eff}$ implies that the AHE in Fe$_{3-x}$GeTe$_2$ should\nbe dominated by the intrinsic Karplus-Luttinger mechanism rather than the\nextrinsic skew-scattering and side-jump mechanisms. The observed deviation in\nthe linear-M Hall conductivity $\\sigma_{xy}^A$ below 30 K is in line with its\ntransport characteristic at low temperatures, implying the scattering of\nconduction electrons due to magnetic disorder and the evolution of the Fermi\nsurface induced by possible spin-reorientation transition.",
        "category": "cond-mat"
    },
    {
        "text": "Measuring Dirac Cones in a Sub-Wavelength Metamaterial: The exciting discovery of bi-dimensional systems in condensed matter physics\nhas triggered the search of their photonic analogues. In this letter, we\ndescribe a general scheme to reproduce some of the systems ruled by a\ntight-binding Hamiltonian in a locally resonant metamaterial: by specifically\ncontrolling the structure and the composition it is possible to engineer the\nband structure at will. We numerically and experimentally demonstrate this\nassertion in the microwave domain by reproducing the band structure of\ngraphene, the most famous example of those 2D-systems, and by accurately\nextracting the Dirac cones. This is a direct evidence that opting for a\ncrystalline description of those sub-wavelength scaled systems, as opposed to\nthe usual description in terms of effective parameters, makes them a really\nconvenient tabletop platform to investigate the tantalizing challenges that\nsolid-state physics offer.",
        "category": "cond-mat"
    },
    {
        "text": "On form-factor expansions for the XXZ chain in the massive regime: We study the large-volume-$L$ limit of form factors of the longitudinal spin\noperators for the XXZ spin-$1/2$ chain in the massive regime. We find that the\nindividual form factors decay as $L^{-n}$, $n$ being an even integer counting\nthe number of physical excitations -- the holes -- that constitute the excited\nstate. Our expression allows us to derive the form-factor expansion of\ntwo-point spin-spin correlation functions in the thermodynamic limit\n$L\\rightarrow +\\infty$. The staggered magnetisation appears naturally as the\nfirst term in this expansion. We show that all other contributions to the\ntwo-point correlation function are exponentially small in the large-distance\nregime.",
        "category": "cond-mat"
    },
    {
        "text": "Memory effects in nonlinear transport: kinetic equations and ratchet\n  devices: We present a new method to derive kinetic equations for systems undergoing\nnon-linear transport in the presence of memory effects. In the framework of\nmesoscopic nonequilibrium thermodynamics, we derive a generalized Fokker-Planck\nequation incorporating memory effects through time-dependent coefficients. As\napplications, we first discuss the non-Markovian dynamics of anomalous\ndiffusion in a potential, analyzing the validity of the fluctuation-dissipation\ntheorem. In a second application, we propose a new ratchet mechanism in which\nthe periodic driving acting on the particle is induced by the Onsager coupling\nof the diffusion current with an oscillating thermodynamic force.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic phase diagram and transport properties of FeGe_2: We have used resistivity measurements to study the magnetic phase diagram of\nthe itinerant antiferromagnet FeGe_2 in the temperature range from 0.3->300 K\nin magnetic fields up to 16 T. In contrast to theoretical predictions, the\nincommensurate spin density wave phase is found to be stable at least up to 16\nT, with an estimated critical field \\mu _0H_c of ~ 30 T. We have also studied\nthe low temperature magnetoresistance in the [100], [110], and [001]\ndirections. The transverse magnetoresistance is well described by a power law\nfor magnetic fields above 1 T with no saturation observed at high fields. We\ndiscuss our results in terms of the magnetic structure and the calculated\nelectronic bandstructure of FeGe_2. We have also observed, for the first time\nin this compound, Shubnikov-de Haas oscillations in the transverse\nmagnetoresistance with a frequency of 190 +- 10 T for a magnetic field along\n[001].",
        "category": "cond-mat"
    },
    {
        "text": "Topological Valley Currents in Bilayer Graphene/Hexagonal Boron Nitride\n  Superlattices: Graphene superlattices have recently been attracting growing interest as an\nemergent class of quantum metamaterials. In this paper, we report the\nobservation of nonlocal transport in bilayer graphene (BLG) superlattices\nencapsulated between two hexagonal boron nitride (hBN) layers, which formed\nhBN/BLG/hBN moir\\'e superlattices. We then employed these superlattices to\ndetect a long-range charge-neutral valley current using an all-electrical\nmethod. The moir\\'e superlattice with broken inversion symmetry leads to a hot\nspot with Berry curvature accumulating at the charge neutral point (CNP), and\nit harbors satellites of the CNP. We observed nonlocal resistance on the order\nof 1 $\\text{k}\\Omega$, which obeys a scaling relation. This nonlocal resistance\nevolves from the quantum Hall effect but without magnetic field/time-reversal\nsymmetry breaking, which is associated with a hot-spot-induced topological\nvalley current. This study should pave the way to developing a\nBerry-phase-sensitive probe to detect hot spots in gapped Dirac materials with\ninversion-symmetry breaking.",
        "category": "cond-mat"
    },
    {
        "text": "Continuum versus discrete flux behaviour in large mesoscopic\n  Bi(2)Sr(2)CaCu(2)O(8+delta) disks: Scanning Hall probe and local Hall magnetometry measurements have been used\nto investigate flux distributions in large mesoscopic superconducting disks\nwith sizes that lie near the crossover between the bulk and mesoscopic vortex\nregimes. Results obtained by directly mapping the magnetic induction profiles\nof the disks at different applied fields can be quite successfully fitted to\nanalytic models which assume a continuous distribution of flux in the sample.\nAt low fields, however, we do observe clear signatures of the underlying\ndiscrete vortex structure and can resolve the characteristic mesoscopic\ncompression of vortex clusters in increasing magnetic fields. Even at higher\nfields, where single vortex resolution is lost, we are still able to track\nconfigurational changes in the vortex patterns, since competing vortex orders\nimpose unmistakable signatures on \"local\" magnetisation curves as a function of\nthe applied field. Our observations are in excellent agreement with molecular\ndynamics numerical simulations which lead us to a natural definition of the\nlengthscale for the crossover between discrete and continuum behaviours in our\nsystem.",
        "category": "cond-mat"
    },
    {
        "text": "Hydrogenated Amorphous Silicon Carbide: A Low-loss Deposited Dielectric\n  for Microwave to Submillimeter Wave Superconducting Circuits: Low-loss deposited dielectrics will benefit superconducting devices such as\nintegrated superconducting spectrometers, superconducting qubits and kinetic\ninductance parametric amplifiers. Compared with planar structures, multi-layer\nstructures such as microstrips are more compact and eliminate radiation loss at\nhigh frequencies. Multi-layer structures are most easily fabricated with\ndeposited dielectrics, which typically exhibit higher dielectric loss than\ncrystalline dielectrics. We measured the sub-kelvin and low-power microwave and\nmm-submm wave dielectric loss of hydrogenated amorphous silicon carbide\n(a-SiC:H), using a superconducting chip with NbTiN/a-SiC:H/NbTiN microstrip\nresonators. We deposited the a-SiC:H by plasma-enhanced chemical vapor\ndeposition at a substrate temperature of 400{\\deg}C. The a-SiC:H has a mm-submm\nloss tangent ranging from $0.80 \\pm 0.01 \\times 10^{-4}$ to $1.43 \\pm 0.04\n\\times 10^{-4}$ in the range of 270 to 385 GHz. The microwave loss tangent is\n$3.2 \\pm 0.2 \\times 10^{-5}$. These are the lowest low-power sub-kelvin loss\ntangents that have been reported for microstrip resonators at mm-submm and\nmicrowave frequencies. We observe that the loss tangent increases with\nfrequency. The a-SiC:H films are free of blisters and have low stress: $-$20\nMPa compressive at 200 nm thickness to 60 MPa tensile at 1000 nm thickness.",
        "category": "cond-mat"
    },
    {
        "text": "Characterization of Electron Pair Velocity in\n  YBa$_{2}$Cu$_{3}$O$_{7-\\textit{$\u03b4$}}$ Thin Films: The superconducting phase transition in\nYBa$_{2}$Cu$_{3}$O$_{7-\\textit{$\\delta $}}$(YBCO) thin film samples doped with\nnon-superconducting nanodot impurities of CeO$_{2}$ are the focus of recent\nhigh-temperature superconductor studies. Non-superconducting holes of the\nsuperconducting lattice induce a bound-state of circulating paired electrons.\nThis creates a magnetic flux vortex state. Examining the flow of free-electrons\nshows that these quantized magnetic flux vortices arrange themselves in a\nself-assembled lattice. The nanodots serve to present structural properties to\nconstrict the \"creep\" of these flux vorticies under a field response in the\nform of a pinning-force enhancing the critical current density after phase\ntransition. In this work, a model for characterizing the superconducting phase\nby the work done on electron pairs and chemical potential, following the\nwell-known theories of Superconductivity (Bardeen-Cooper-Scheifer \\&\nGinzburg-Landau), is formulated and tested.A solution to the expression for the\nmagnetic flux, zero net force and pair velocity will generate a setting for the\noptimal deposition parameters of number density, growth geometry and mass\ndensity of these nanodot structures.",
        "category": "cond-mat"
    },
    {
        "text": "Effects of liquid fraction and contact angle on structure and coarsening\n  in two-dimensional foams: Aqueous foams coarsen with time due to gas diffusion through the liquid. The\nmean bubble size grows, and small bubbles vanish. However, coarsening is little\nunderstood for foams with an intermediate liquid content, particularly in the\npresence of surfactant-induced attractive forces between the bubbles, measured\nby the contact angle. Rigorous bubble growth laws have yet to be developed, and\nthe evolution of bulk foam properties is unclear. We present a quasi-static\nnumerical model for coarsening in two-dimensional wet foams, focusing on growth\nlaws and related bubble properties. The deformation of bubbles is modelled\nusing a finite-element approach, and the gas flow through both films and\nPlateau borders is approximated. We give results for disordered two-dimensional\nwet foams with 256 to 1024 bubbles, at liquid fractions from $2\\%$ to beyond\nthe zero-contact-angle jamming transition, and with contact angles up to\n$10^\\circ$. Simple analytical models are developed to aid interpretation. We\nfind that nonzero contact angle causes a proxy of the initial coarsening rate\nto plateau at large liquid fractions, and that the individual bubble growth\nrates are closely related to their effective number of neighbours.",
        "category": "cond-mat"
    },
    {
        "text": "Evolution of electronic structure of Ru-doped single-crystal iridiates,\n  Sr$_2$Ir$_{1-x}$Ru$_x$O$_4$: We investigated Ru-doped single-crystal 5$d$ iridiates,\nSr$_2$Ir$_{1-x}$Ru$_x$O$_{4}$, at three different doping concentrations ($x =$\n0.01, 0.07 and 0.10) using optical spectroscopy. The undoped pristine compound\n(Sr$_2$IrO$_{4}$) is known as a novel $J_{eff}$ = 1/2 Mott insulator.\nRemarkably, the optical conductivity spectra of all three samples exhibited the\ninsulating behavior, although we observed weak Drude components in the optical\nconductivity spectra down to the lowest temperature of 30 K. The charge-carrier\ndensities of the Ru-doped iridiates estimated from the Drude components are\nsignificantly smaller than the expected values estimated from the nominal\nRu-doping concentrations. Herein, we provide temperature- and doping-dependent\nelectronic structure evolution of Ru-doped iridiates. We expect that our\nresults will be useful for understanding the intriguing Ru-doping-dependent\nproperties of 5$d$ iridiate Sr$_2$IrO$_{4}$.",
        "category": "cond-mat"
    },
    {
        "text": "Room-Temperature Superconductivity in Boron-Nitrogen Doped Lanthanum\n  Superhydride: Recent theoretical and experimental studies of hydrogen-rich materials at\nmegabar pressures (i.e., >100 GPa) have led to the discovery of very\nhigh-temperature superconductivity in these materials. Lanthanum superhydride\nLaH$_{10}$ has been of particular focus as the first material to exhibit a\nsuperconducting critical temperature (T$_c$) near room temperature. Experiments\nindicate that the use of ammonia borane as the hydrogen source can increase the\nconductivity onset temperatures of lanthanum superhydride to as high as 290 K.\nHere we examine the doping effects of B and N atoms on the superconductivity of\nLaH$_{10}$ in its fcc (Fm-3m) clathrate structure at megabar pressures. Doping\nat H atomic positions strengthens the H$_{32}$ cages of the structure to give\nhigher phonon frequencies that enhance the Debye frequency and thus the\ncalculated T$_c$. The predicted T$_c$ can reach 288 K in\nLaH$_{9.985}$N$_{0.015}$ within the average high-symmetry structure at 240 GPa.",
        "category": "cond-mat"
    },
    {
        "text": "Segregated quantum phases of dipolar bosonic mixtures in two-dimensional\n  optical lattices: We identify the quantum phases in a binary mixture of dipolar bosons in\ntwo-dimensional optical lattices. Our study is motivated by the recent\nexperimental realization of binary dipolar condensate mixtures of Er-Dy [Phys.\nRev. Lett. 121, 213601 (2018)]. We model the system by using the extended\ntwo-species Bose-Hubbard model and calculate the ground-state phase diagrams by\nusing mean-field theory. For selected cases we also obtain analytical phase\nboundaries by using the site-decoupled mean-field theory. For comparison we\nalso examine the phase diagram of two-species Bose-Hubbard model. Our results\nshow that the quantum phases with the long-range intraspecies interaction phase\nseparate with no phase ordering. The introduction of the long-range\ninterspecies interaction modifies the quantum phases of the system. It leads to\nthe emergence of phase-separated quantum phases with phase ordering. The\ntransition from the phase-separated quantum phases without phase ordering to\nphase ordered ones breaks the inversion symmetry.",
        "category": "cond-mat"
    },
    {
        "text": "Structure of inactive states of a binary Lennard-Jones mixture: We study the structure of inactive states in a prototypical model glass, the\nKob-Andersen binary Lennard-Jones mixture. These inactive states are obtained\nby transition path sampling and are at dynamical phase coexistence with an\nactive equilibrium state. Configurations in the inactive states are kinetically\nstable and are located in deeper basins of the energy landscape than their\nactive counterparts. By analyzing trajectory-to-trajectory fluctuations within\nthe inactive state, we assess correlations between kinetic stability, energy\nand other structural properties. We show that measures of local order\nassociated to stable local packings and bond-orientational order are weakly\ncorrelated with energy and kinetic stability. We discuss what kinds of\nstructural measurement might capture the relevant dynamical features of the\ninactive state.",
        "category": "cond-mat"
    },
    {
        "text": "A general moment NRIXS approach to the determination of equilibrium Fe\n  isotopic fractionation factors: application to goethite and jarosite: We measured the reduced partition function ratios for iron isotopes in\ngoethite FeO(OH), potassium-jarosite KFe3(SO4)2(OH)6, and hydronium-jarosite\n(H3O)Fe3(SO4)2(OH)6, by Nuclear Resonant Inelastic X-Ray Scattering (NRIXS,\nalso known as Nuclear Resonance Vibrational Spectroscopy -NRVS- or Nuclear\nInelastic Scattering -NIS) at the Advanced Photon Source. These measurements\nwere made on synthetic minerals enriched in 57Fe. A new method (i.e., the\ngeneral moment approach) is presented to calculate {\\beta}-factors from the\nmoments of the NRIXS spectrum S(E). The first term in the moment expansion\ncontrols iron isotopic fractionation at high temperature and corresponds to the\nmean force constant of the iron bonds, a quantity that is readily measured and\noften reported in NRIXS studies.",
        "category": "cond-mat"
    },
    {
        "text": "Femtosecond optical breakdown in silicon: We investigate photoinization, energy deposition, plasma formation and the\nultrafast optical breakdown in crystalline silicon irradiated by intense\nnear-infrared laser pulses with pulse duration $\\tau \\le $ 100 fs. The\noccurrence of high-intensity breakdown was established by the sudden increase\nof the absorbed laser energy inside the bulk, which corresponds to threshold\nenergy fluence $\\Phi_{th} > $ 1 J/cm$^2$. The optical breakdown is accompanied\nby severe spectral broadening of the transmitted pulse. For the studied\nirradiation conditions, we find that the threshold fluence increases linearly\nwith the increase of the pulse duration, while the corresponding laser\nintensity threshold decreases. The effect of the high plasma density on the\nstability of diamond lattice is also examined. For near threshold fluences,\nwhen about 5 \\% of valence electrons are promoted into the conduction band, the\nSi-Si bonds are softened and large Fermi degeneracy pressure arises (with\npressure up to 100 kbar). The mechanical instability of the diamond lattice\nsuggests that the large number of electron-hole pairs leads directly to\nultrafast melting of the crystal structure.",
        "category": "cond-mat"
    },
    {
        "text": "Classifying transport behavior via current fluctuations in open quantum\n  systems: There are two standard ways of classifying transport behavior of systems. The\nfirst is via time scaling of spread of correlations in the isolated system in\nthermodynamic limit. The second is via system size scaling of conductance in\nthe steady state of the open system. We show here that these correspond to\ntaking the thermodynamic limit and the long time limit of the integrated\nequilibrium current-current correlations of the open system in different order.\nIn general, the limits may not commute leading to a conflict between the two\nstandard ways of transport classification. Nevertheless, the full information\nis contained in the equilibrium current-current correlations of the open\nsystem. We show this analytically by rigorously deriving the open-system\ncurrent fluctuation dissipation relations (OCFDR) starting from an extremely\ngeneral open quantum set-up and then carefully taking the proper limits. We\ntest our theory numerically on the non-trivial example of the critical\nAubry-Andr\\'e-Harper (AAH) model, where, it has been recently shown that, the\ntwo standard classifications indeed give different results. We find that both\nthe total current autocorrelation and the long-range local current correlations\nof the open system in equilibrium show signatures of diffusive transport up to\na time scale. This time scale grows as square of system size. Beyond this time\nscale a steady state value is reached. The steady state value is conductance,\nwhich shows sub-diffusive scaling with system size.",
        "category": "cond-mat"
    },
    {
        "text": "Wood compression in four-dimensional in situ tomography: Wood deformation, in particular when subject to compression, exhibits\nscale-free avalanche-like behavior as well as structure-dependent localization\nof deformation. We have taken three-dimensional (3D) x-ray tomographs during\ncompression with constant stress rate loading. Using digital volume\ncorrelation, we obtain the local total strain during the experiment and compare\nit to the global strain and acoustic emission. The wood cells collapse layer by\nlayer throughout the sample starting from the softest parts, i.e., the spring\nwood. As the damage progresses, more and more of the softwood layers throughout\nthe sample collapse, which indicates damage spreading instead of localization.\nIn 3D, one can see a fat-tailed local strain rate distribution, indicating that\ninside the softwood layers, the damage occurs in localized spots. The observed\nlog-normal strain distribution is in agreement with this view of the\ndevelopment of independent local collapses or irreversible deformation events.\nA key feature in the mechanical behavior of wood is then in the complex\ninteraction of localized deformation between or among the annual rings.",
        "category": "cond-mat"
    },
    {
        "text": "Tomonaga-Luttinger liquid parameters of magnetic waveguides in graphene: Electronic waveguides in graphene formed by counterpropagating snake states\nin suitable inhomogeneous magnetic fields are shown to constitute a realization\nof a Tomonaga-Luttinger liquid. Due to the spatial separation of the right- and\nleft-moving snake states, this non-Fermi liquid state induced by\nelectron-electron interactions is essentially unaffected by disorder. We\ncalculate the interaction parameters accounting for the absence of Galilei\ninvariance in this system, and thereby demonstrate that non-Fermi liquid\neffects are significant and tunable in realistic geometries.",
        "category": "cond-mat"
    },
    {
        "text": "Condensation of classical nonlinear waves: We study the formation of a large-scale coherent structure (a condensate) in\nclassical wave equations by considering the defocusing nonlinear Schr\\\"odinger\nequation as a representative model. We formulate a thermodynamic description of\nthe condensation process by using a wave turbulence theory with ultraviolet\ncut-off. In 3 dimensions the equilibrium state undergoes a phase transition for\nsufficiently low energy density, while no transition occurs in 2 dimensions, in\nanalogy with standard Bose-Einstein condensation in quantum systems. Numerical\nsimulations show that the thermodynamic limit is reached for systems with\n$16^3$ computational modes and greater. On the basis of a modified wave\nturbulence theory, we show that the nonlinear interaction makes the transition\nto condensation subcritical. The theory is in quantitative agreement with the\nsimulations.",
        "category": "cond-mat"
    },
    {
        "text": "Aging-induced continuous phase transition: Aging is considered as the property of the elements of a system to be less\nprone to change states as they get older. We incorporate aging into the noisy\nvoter model, a stochastic model in which the agents modify their binary state\nby means of noise and pair-wise interactions. Interestingly, due to aging the\nsystem passes from a finite-size discontinuous transition between ordered\n(ferromagnetic) and disordered (paramagnetic) phases to a second order phase\ntransition, well defined in the thermodynamic limit, belonging to the Ising\nuniversality class. We characterize it analytically by finding the stationary\nsolution of an infinite set of mean field equations. The theoretical\npredictions are tested with extensive numerical simulations in low dimensional\nlattices and complex networks. We finally employ the aging properties to\nunderstand the symmetries broken in the phase transition.",
        "category": "cond-mat"
    },
    {
        "text": "Fluctuations and scaling in creep deformation: The spatial fluctuations of deformation are studied in creep in the Andrade's\npower-law and the logarithmic phases, using paper samples. Measurements by the\nDigital Image Correlation technique show that the relative strength of the\nstrain rate fluctuations increases with time, in both creep regimes. In the\nAndrade creep phase characterized by a power law decay of the strain rate\n$\\epsilon_t \\sim t^{-\\theta}$, with $\\theta \\approx 0.7$, the fluctuations obey\n$\\Delta \\epsilon_t \\sim t^{-\\gamma}$, with $\\gamma \\approx 0.5$. The local\ndeformation follows a data collapse appropriate for an absorbing\nstate/depinning transition. Similar behavior is found in a crystal plasticity\nmodel, with a jamming or yielding phase transition.",
        "category": "cond-mat"
    },
    {
        "text": "Neural Network Analytic Continuation for Monte Carlo: Improvement by\n  Statistical Errors: This study explores the use of neural network-based analytic continuation to\nextract spectra from Monte Carlo data. We apply this technique to both\nsynthetic and Monte Carlo-generated data. The training sets for neural networks\nare carefully synthesized without ``data leakage\". We found that the training\nset should match the input correlation functions in terms of statistical error\nproperties, such as noise level, noise dependence on imaginary time, and\nimaginary time-displaced correlations. We have developed a systematic method to\nsynthesize such training datasets. Our improved algorithm outperform the widely\nused maximum entropy method in highly noisy situations. As an example, our\nmethod successfully extracted the dynamic structure factor of the spin-1/2\nHeisenberg chain from quantum Monte Carlo simulations.",
        "category": "cond-mat"
    },
    {
        "text": "The height distribution of the KPZ equation with sharp wedge initial\n  condition: numerical evaluations: The time-dependent probability distribution function of the height for the\nKardar-Parisi-Zhang equation with sharp wedge initial conditions has been\nobtained recently as a convolution between the Gumbel distribution and a\ndifference of two Fredholm determinants. We evaluate numerically this\ndistribution over the whole time span. The crossover from the short time\nbehavior, which is Gaussian, to the long time behavior, which is governed by\nthe GUE Tracy-Widom distribution, is clearly visible.",
        "category": "cond-mat"
    },
    {
        "text": "Improving Electric Contacts to Two-Dimensional Semiconductors: Electrical contact resistance to two-dimensional (2D) semiconductors such as\nmonolayer MoS_{2} is a key bottleneck in scaling the 2D field effect\ntransistors (FETs). The 2D semiconductor in contact with three-dimensional\nmetal creates unique current crowding that leads to increased contact\nresistance. We developed a model to separate the contribution of the current\ncrowding from the intrinsic contact resistivity. We show that current crowding\ncan be alleviated by doping and contact patterning. Using Landauer-B\\\"uttiker\nformalism, we show that van der Waals (vdW) gap at the interface will\nultimately limit the electrical contact resistance. We compare our models with\nexperimental data for doped and undoped MoS_{2} FETs. Even with heavy\ncharge-transfer doping of > 2x10^{13} cm^{-2}, we show that the\nstate-of-the-art contact resistance is 100 times larger than the ballistic\nlimit. Our study highlights the need to develop efficient interface to achieve\ncontact resistance of < 10 {\\Omega}.{\\mu}m, which will be ideal for extremely\nscaled devices.",
        "category": "cond-mat"
    },
    {
        "text": "Monolayer MoS$_2$ Strained to 1.3\\% with a Microelectromechanical System: We report on a modified transfer technique for atomically thin materials\nintegrated onto microelectromechanical systems (MEMS) for studying strain\nphysics and creating strain-based devices. Our method tolerates the non-planar\nstructures and fragility of MEMS, while still providing precise positioning and\ncrack free transfer of flakes. Further, our method used the transfer polymer to\nanchor the 2D crystal to the MEMS, which reduces the fabrication time,\nincreases the yield, and allowed us to exploit the strong mechanical coupling\nbetween 2D crystal and polymer to strain the atomically thin system. We\nsuccessfully strained single atomic layers of molybdenum disulfide (MoS$_2$)\nwith MEMS devices for the first time and achieved greater than 1.3\\% strain,\nmarking a major milestone for incorporating 2D materials with MEMS We used the\nestablished strain response of MoS$_2$ Raman and Photoluminescence spectra to\ndeduce the strain in our crystals and provide a consistency check. We found\ngood comparison between our experiment and literature.",
        "category": "cond-mat"
    },
    {
        "text": "Emergent Spacetime in Quantum Lattice Models: Many quantum lattice models have an emergent relativistic description in\ntheir continuum limit. The celebrated example is graphene, whose continuum\nlimit is described by the Dirac equation on a Minkowski spacetime. Not only\ndoes the continuum limit provide us with a dictionary of geometric observables\nto describe the models with, but it also allows one to solve models that were\notherwise analytically intractable. In this thesis, we investigate novel\nfeatures of this relativistic description for a range of quantum lattice\nmodels. In particular, we demonstrate how to generate emergent curved\nspacetimes and identify observables at the lattice level which reveal this\nemergent behaviour, allowing one to simulate relativistic effects in the\nlaboratory. We first study carbon nanotubes, a system with an edge, which\nallows us to test the interesting feature of the Dirac equation that it allows\nfor bulk states with support on the edges of the system. We then study Kitaev's\nhoneycomb model which has a continuum limit describing Majorana spinors on a\nMinkowski spacetime. We show how to generate a non-trivial metric in the\ncontinuum limit of this model and how to observe the effects of this metric and\nits corresponding curvature in the lattice observables, such as Majorana\ncorrelators, Majorana zero modes and the spin densities. We also discuss how\nlattice defects and $\\mathbb{Z}_2$ gauge fields at the lattice level can\ngenerate chiral gauge fields in the continuum limit and we reveal their\nadiabatic equivalence. Finally, we discuss a chiral modification of the 1D XY\nmodel which makes the model interacting and introduces a non-trivial phase\ndiagram. We see that this generates a black hole metric in the continuum limit,\nwhere the inside and outside of the black hole are in different phases. We then\ndemonstrate that by quenching this model we can simulate Hawking radiation.",
        "category": "cond-mat"
    },
    {
        "text": "Conventional Superconductivity properties of the ternary boron-nitride\n  Nb2BN: Superconducting bulk properties of ternary Nb2 BN are confirmed and are\ndescribed by means of magnetization, electronic transport and specific-heat\nmeasurements. BCS conventional super- conductivity is found with Tc = 4.4 K.\nCritical fields Hc1 (0)= 93 Oe and Hc2 (0)= 2082 Oe are extrapolated by\nmagnetic and resistivity measurements. The specific heat data reveals {\\gamma}\n= 6.3 mJ/mol K2 and {\\beta} = 0.293 mJ/mol K4 in good agreement with the BCS\nTheory.",
        "category": "cond-mat"
    },
    {
        "text": "Influence of electric fields on dielectric properties of GPI\n  ferroelectric: Using modified microscopic model of GPI by taking into account the\npiezoelectric coupling with strains $\\varepsilon_i$ in the frames of\ntwo-particle cluster approximation, the components of polarization vector and\nstatic dielectric permittivity tensor of the crystal at applying the external\ntransverse electric fields $E_1$ and $E_3$ are calculated. An analysis of the\ninfluence of these fields on thermodynamic characteristics of GPI is carried\nout. A satisfactory quantitative description of the available experimental data\nfor these characteristics has been obtained at a proper choice of the model\nparameters.",
        "category": "cond-mat"
    },
    {
        "text": "Current-induced birefringent absorption and non-reciprocal plasmons in\n  graphene: We present extensive calculations of the optical and plasmonic properties of\na graphene sheet carrying a dc current. By calculating analytically the\ndensity-density response function of current-carrying states at finite\ntemperature, we demonstrate that an applied dc current modifies the Pauli\nblocking mechanism and that absorption acquires a birefringent character with\nrespect to the angle between the in-plane light polarization and current flow.\nEmploying the random phase approximation at finite temperature, we show that\ngraphene plasmons display a degree of non-reciprocity and collimation that can\nbe tuned with the applied current. We discuss the possibility to measure these\neffects.",
        "category": "cond-mat"
    },
    {
        "text": "Contraction and expansion effects on the substitution-defect properties\n  of thirteen alloying elements in bcc Fe: Proposed as blanket structural materials for fusion power reactors, reduced\nactivation ferritic/martensitic (RAFM) steel undergoes volume expanding and\ncontracting in a cyclic mode under service environment. Particularly, being\nsubjected to significant fluxes of fusion neutrons RAFM steel suffers\nconsiderable local volume variations in the radiation damage involved regions.\nIt is necessary to study the structure properties of the alloying elements in\ncontraction and expansion states. In this paper we studied local substitution\nstructures of thirteen alloying elements Al, Co, Cr, Cu, Mn, Mo, Nb, Ni, Si,\nTa, Ti, V, and W in bcc Fe and calculated their substitutional energies in the\nvolume variation range from -1.0% to 1.0%. From the structure relaxation\nresults of the first five neighbor shells around the substitutional atom we\nfind the relaxation in each neighbor shell keeps approximately uniform within\nthe volume variation from -1.0% to 1.0% except those of Mn and the relaxation\nof the fifth neighbor shell is stronger than that of the third and forth,\nindicating that the lattice distortion due to the substitution atom is easier\nto spread in <111> direction than in other direction. The relaxation pattern\nand intensity are related to the size and electron structure of the\nsubstitutional atom. For some alloying elements, such as Mo, Nb, Ni, Ta, Ti and\nW, the substitutional energy decreases noticeably when the volume increases.\nFurther analysis show that the substitutional energy comprises the energy\nvariation originated from local structure relaxation and the chemical potential\ndifference of the substitutional atom between its elemental crystalline state\nand the solid solution phase in bcc Fe. We think the approximately uniform\nrelaxation of each neighbor shell around a substitutional atom give rise to a\nlinear decrease in the substitutional energy with the increasing volume.",
        "category": "cond-mat"
    },
    {
        "text": "Symmetry-enforced planar nodal chain phonons in non-symmorphic materials: Topological semimetal states which are constrained by symmetries and give\nbirth to innovative excitations are the frontiers of topological quantum\nmatter. Nodal chains in which two nodal rings connect at one point were first\ndiscovered in non-symmorphic electronic systems and then generalized to\nsymmorphic phononic systems. In this work, we identify a new class of planar\nnodal chains in non-symmorphic phononic systems, where the connecting rings lie\nin the same plane. The constituting nodal rings are protected by mirror\nsymmetry, their intersection is guaranteed by the combination of time-reversal\nand non-symmorphic two-fold screw symmetry. In addition, the connecting points\nare four-fold degenerate while those in previous works are two-fold degenerate.\nWe searched all 230 space groups and found 8 space groups that can host the\nproposed planar nodal chain phonons. Taking wurtzite GaN (space group No.186)\nas an example, the planar nodal chain is confirmed by first-principles\ncalculations. The planar nodal chains result in two distinct classes of\ndrumhead surface. The first category lies on the [10(-1)0] surface Brillouin\nzone and the second lies on the [0001] surface Brillouin zone. Our finding\nreveals a class of planar nodal chains in non-symmorphic phononic systems,\nexpands the catalog of topological nodal chains, and enriches the family of\ntopological surface states.",
        "category": "cond-mat"
    },
    {
        "text": "Chiral hedgehog textures in 2D XY-like ordered domains: The textures associated with a point defect centered in a circular domain of\na thin film with XY-like ordering have been analyzed. The family of equilibrium\ntextures, both stable and metastable, can be classified by a new radial\ntopological number in addition to the winding number of the defect. Chiral\ntextures are supported in an achiral system as a result of spontaneously broken\nchiral symmetry. Among these chiral textures, our theoretical analysis\naccurately describes two categories of recently discovered ``reversing spiral''\ntextures, ones that are energetically stable and metastable.",
        "category": "cond-mat"
    },
    {
        "text": "Hall Conductivity in the presence of repulsive magnetic impurities: The Hall conductivity of disordered magnetic systems consisting of hard-core\npoint vortices randomly dropped on the plane with a Poissonian distribution,\nhas a behavior analogous to the one observed experimentally by R.~J.~Haug,\nR.~R.~Gerhardts, K.~v.~Klitzling and K.~Ploog, with repulsive scatterers \\cite\n{1}. We also argue that models of homogeneous magnetic field with disordered\npotential, have necessarily vanishing Hall conductivities when their Hilbert\nspace is restricted to a given Landau level subspace.",
        "category": "cond-mat"
    },
    {
        "text": "Parametric statistics of the scattering matrix: From metallic to\n  insulating quasi-unidimensional disordered systems: We investigate the statistical properties of the scattering matrix $S$\ndescribing the electron transport through quasi-one dimensional disordered\nsystems. For weak disorder (metallic regime), the energy dependence of the\nphase shifts of $S$ is found to yield the same universal parametric\ncorrelations as those characterizing chaotic Hamiltonian eigenvalues driven by\nan external parameter. This is analyzed within a Brownian-motion model for $S$,\nwhich is directly related to the distribution of the Wigner-Smith delay time\nmatrix. For large disorder (localized regime), transport is dominated by\nresonant tunneling and the universal behavior disappears. A model based on a\nsimplified description of the localized wave functions qualitatively explains\nour numerical results. In the insulator, the parametric correlation of the\nphase shift velocities follows the energy-dependent autocorrelator of the\nWigner time. The Wigner time and the conductance are correlated in the metal\nand in the insulator.",
        "category": "cond-mat"
    },
    {
        "text": "Crow instability in trapped Bose-Einstein condensates: We show theoretically that elongated vortex-antivortex dipoles can be created\ncontrollably in trapped Bose-Einstein condensates, using known experimental\ntechniques. Vortex dipoles of sufficient length are unstable and cascade into\nslow vortex rings which ultimately decay via sound emission. This instability\nof antiparallel vortex line elements, which self-generates Kelvin waves on\nvortex loops and in trapped atomic gases, may play a role in bridging the\nKelvin-wave and Kolmogorov-Richardson cascades of quantum turbulence.",
        "category": "cond-mat"
    },
    {
        "text": "Devil's staircases, quantum dimer models, and stripe formation in strong\n  coupling models of quantum frustration: We construct a two-dimensional microscopic model of interacting quantum\ndimers that displays an infinite number of periodic striped phases in its T=0\nphase diagram. The phases form an incomplete devil's staircase and the period\nbecomes arbitrarily large as the staircase is traversed. The Hamiltonian has\npurely short-range interactions, does not break any symmetries of the\nunderlying square lattice, and is generic in that it does not involve the\nfine-tuning of a large number of parameters. Our model, a quantum mechanical\nanalog of the Pokrovsky-Talapov model of fluctuating domain walls in two\ndimensional classical statistical mechanics, provides a mechanism by which\nstriped phases with periods large compared to the lattice spacing can, in\nprinciple, form in frustrated quantum magnetic systems with only short-ranged\ninteractions and no explicitly broken symmetries.",
        "category": "cond-mat"
    },
    {
        "text": "Robustness and observability of rotating vortex-lattices in an\n  exciton-polariton condensate: Exciton-polariton condensates display a variety of intriguing pattern-forming\nbehaviors, particularly when confined in potential traps. It has previously\nbeen predicted that triangular lattices of vortices of the same sign will form\nspontaneously as the result of surface instabilities in a harmonic trap.\nHowever, natural disorder, deviation of the external potential from circular\nsymmetry, or higher-order terms modifying the dynamical equations may all have\ndetrimental effects and destabilize the circular trajectories of vortices. Here\nwe address these issues, by characterizing the robustness of the vortex lattice\nagainst disorder and deformations of the trapping potential. Since most\nexperiments use time integrated measurements it would be hard to observe\ndirectly the rotating vortex lattices or distinguish them from vortex-free\nstates. We suggest how these difficulties can be overcome and present an\nexperimentally viable interference-imaging scheme that would allow the\ndetection of rotating vortex lattices.",
        "category": "cond-mat"
    },
    {
        "text": "Measurement of the \u03bd= 1/3 fractional quantum Hall energy gap in\n  suspended graphene: We report on magnetotransport measurements of multi-terminal suspended\ngraphene devices. Fully developed integer quantum Hall states appear in\nmagnetic fields as low as 2 T. At higher fields the formation of longitudinal\nresistance minima and transverse resistance plateaus are seen corresponding to\nfractional quantum Hall states, most strongly for {\\nu}= 1/3. By measuring the\ntemperature dependence of these resistance minima, the energy gap for the 1/3\nfractional state in graphene is determined to be at ~20 K at 14 T.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-controlled Mott-Hubbard bands in LaMnO_3 probed by optical\n  ellipsometry: Spectral ellipsometry has been used to determine the dielectric function of\nan untwinned crystal of LaMnO_3 in the spectral range 0.5-5.6 eV at\ntemperatures 50 K < T < 300 K. A pronounced redistribution of spectral weight\nis found at the Neel temperature T_N = 140 K. The anisotropy of the spectral\nweight transfer matches the magnetic ordering pattern. A superexchange model\nquantitatively describes spectral weight transfer induced by spin correlations.\nThis analysis implies that the lowest-energy transitions around 2 eV are\nintersite d-d transitions, and that LaMnO_3 is a Mott-Hubbard insulator.",
        "category": "cond-mat"
    },
    {
        "text": "First order character and observable signatures of topological quantum\n  phase transitions: Topological quantum phase transitions are characterised by changes in global\ntopological invariants. These invariants classify many body systems beyond the\nconventional paradigm of local order parameters describing spontaneous symmetry\nbreaking. For non-interacting electrons, it is well understood that such\ntransitions are continuous and always accompanied by a gap-closing in the\nenergy spectrum, given that the symmetries protecting the topological phase are\nmaintained. Here, we demonstrate that sufficiently strong electron-electron\ninteraction can fundamentally change the situation: we discover a topological\nquantum phase transition of first order character in the genuine thermodynamic\nsense, that occurs without gap closing. Our theoretical study reveals the\nexistence of a quantum critical endpoint associated with an orbital instability\non the transition line between a 2D topological insulator and a trivial band\ninsulator. Remarkably, this phenomenon entails unambiguous signatures\nassociated to the orbital occupations that can be detected experimentally.",
        "category": "cond-mat"
    },
    {
        "text": "Jerk current: A novel bulk photovoltaic effect: We investigate a physical divergence of the third order polarization\nsusceptibility representing a photoinduced current in biased crystalline\ninsulators. This current grows quadratically with illumination time in the\nabsence of momentum relaxation and saturation; we refer to it as the\n\\textit{jerk current}. Two contributions to the current are identified. The\nfirst is a hydrodynamic acceleration of optically injected carriers by the\nstatic electric field, and the second is the change in the carrier injection\nrate in the presence of the static electric field. The jerk current can have a\ncomponent perpendicular to the static field, a feature not captured by standard\nhydrodynamic descriptions of carriers in electric fields. We suggest an\nexperiment to detect the jerk current and some of its interesting features.",
        "category": "cond-mat"
    },
    {
        "text": "Rotation-induced macromolecular spooling of DNA: Genetic information is stored in a linear sequence of base-pairs; however,\nthermal fluctuations and complex DNA conformations such as folds and loops make\nit challenging to order genomic material for in vitro analysis. In this work,\nwe discover that rotation-induced macromolecular spooling of DNA around a\nrotating microwire can monotonically order genomic bases, overcoming this\nchallenge. We use single-molecule fluorescence microscopy to directly visualize\nlong DNA strands deforming and elongating in shear flow near a rotating\nmicrowire, in agreement with numerical simulations. While untethered DNA is\nobserved to elongate substantially, in agreement with our theory and numerical\nsimulations, strong extension of DNA becomes possible by introducing tethering.\nFor the case of tethered polymers, we show that increasing the rotation rate\ncan deterministically spool a substantial portion of the chain into a fully\nstretched, single-file conformation. When applied to DNA, the fraction of\ngenetic information sequentially ordered on the microwire surface will increase\nwith the contour length, despite the increased entropy. This ability to handle\nlong strands of DNA is in contrast to modern DNA sample preparation\ntechnologies for sequencing and mapping, which are typically restricted to\ncomparatively short strands resulting in challenges in reconstructing the\ngenome. Thus, in addition to discovering new rotation-induced macromolecular\ndynamics, this work inspires new approaches to handling genomic-length DNA\nstrands.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum contact process: The contact process is a paradigmatic classical stochastic system displaying\ncritical behavior even in one dimension. It features a non-equilibrium phase\ntransition into an absorbing state that has been widely investigated and shown\nto belong to the directed percolation universality class. When the same process\nis considered in a quantum setting much less is known. So far mainly\nsemi-classical studies have been conducted and the nature of the transition in\nlow dimensions is still a matter of debate. Also from a numerical point of\nview, from which the system may look fairly simple --- especially in one\ndimension --- results are lacking. In particular the presence of the absorbing\nstate poses a substantial challenge which appears to affect the reliability of\nalgorithms targeting directly the steady-state. Here we perform real-time\nnumerical simulations of the open dynamics of the quantum contact process and\nshed light on the existence and on the nature of an absorbing state phase\ntransition in one dimension. We find evidence for the transition being\ncontinuous and provide first estimates for the critical exponents. Beyond the\nconceptual interest, the simplicity of the quantum contact process makes it an\nideal benchmark problem for scrutinizing numerical methods for open quantum\nnon-equilibrium systems.",
        "category": "cond-mat"
    },
    {
        "text": "Weyl semimetals and superconductors designed in an orbital selective\n  superlattice: We propose two complementary design principles for engineering\nthree-dimensional (3D) Weyl semimetals and superconductors in a layer-by-layer\nsetup which includes even and odd parity orbitals in alternating layers -\ndubbed orbital selective superlattice. Such structure breaks mirror symmetry\nalong the superlattice growth axis which, with the help of either a basal plane\nspin-orbit coupling or a spinless p+ip superconductivity, stabilizes a 3D Dirac\nnode. To explore this idea, we develop a 3D generalization of Haldane model and\na Bogoliubov-de-Gennes (BdG) Hamiltonian for the two cases, respectively, and\nshow that a tunable single or multiple Weyl nodes with linear dispersion in all\nspatial directions can be engineered desirably in a widespread parameter space.\nWe also demonstrate that a single helical Weyl band can be created at the\n$\\Gamma$-point at the Fermi level in the superconducting case via gapping out\neither of the orbital state by violating its particle-hole symmetry but not any\nother symmetries. Finally, implications of our results for the realization of\nanomalous Hall effect and Majorana bound state are discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Correlations between mechanical, structural, and dynamical properties of\n  polymer nanocomposites: We study the structural and dynamical mechanisms of reinforcement of a\npolymer nanocomposite (PNC) via coarse-grained molecular dynamics simulations.\nIn a regime of strong polymer-filler interactions, the stress at failure of the\nPNC is clearly correlated to structural quantities, such as the filler loading,\nthe surface area of the polymer-filler interface, and the network structure.\nAdditionally, we find that small fillers, of the size of the polymer monomers,\nare the most effective at reinforcing the matrix by surrounding the polymer\nchains and maximizing the number of strong polymer-filler interactions. Such a\nstructural configuration is correlated to a dynamical feature, namely, the\nminimization of the relative mobility of the fillers with respect to the\npolymer matrix.",
        "category": "cond-mat"
    },
    {
        "text": "Emergent channel over a pair of pockets in strong density waves: Different channels over which electrons scatter between parts of the Fermi\nsurface are the key to various electronic quantum matters, such as\nsuperconductivity and density waves. We consider an effective model in higher\ndimensions where each of the two pockets in the original model maps to (the\nLandau levels of) two Dirac fermions. We discover an emergent channel when two\nDirac fermions from different pairs annihilate, where the presence of a strong\ndensity wave is essential. We support our analysis with numerical calculations\non model examples in the vicinity of ferromagnetic and antiferromagnetic\norders. We also discuss interesting consequences on electron interaction\nchannels that beyond-mean-field fluctuations may induce.",
        "category": "cond-mat"
    },
    {
        "text": "Coupled Effects in Quantum Dot Nanostructures with Nonlinear Strain and\n  Bridging Modelling Scales: We demonstrate that the conventional application of linear models to the\nanalysis of optoelectromechanical properties of nanostructures in bandstructure\nengineering could be inadequate. The focus of the present paper is on a model\nbased on the coupled Schrodinger-Poisson system where we account consistently\nfor the piezoelectric effect and analyze the influence of different nonlinear\nterms in strain components. The examples given in this paper show that the\npiezoelectric effect contributions are essential and have to be accounted for\nwith fully coupled models. While in structural applications of piezoelectric\nmaterials at larger scales, the minimization of the full electromechanical\nenergy is now a routine in many engineering applications, in bandstructure\nengineering conventional approaches are still based on linear models with\nminimization of uncoupled, purely elastic energy functionals with respect to\ndisplacements. Generalizations of the existing models for bandstructure\ncalculations are presented in this paper in the context of coupled effects.",
        "category": "cond-mat"
    },
    {
        "text": "Structural reconstruction and anisotropic conductance in\n  $4f$-ferromagnetic monolayer: Two-dimensional magnets are promising for nanoscale spintronic applications.\nCurrently, most available candidates are based on $3d$ transition metal\ncompounds, with hexagonal or honeycomb lattice geometry. Here, a GdCl$_3$\nmonolayer with $4f$ moments is theoretically studied, which can be exfoliated\nfrom its existing bulk. Its orthorhombic structure and hendecahedral ion cages\nare unique in two-dimensional. Furthermore, a significant structural\nreconstruction is caused by the implantation of Li atoms into its interstitial\nposition, which also lead to ferromagnetism via a double-exchange-like process.\nIts highly anisotropic conductance may be peculiarly useful for\nnanoelectronics.",
        "category": "cond-mat"
    },
    {
        "text": "Finite-temperature critical point of a glass transition: We generalize the simplest kinetically constrained model of a glass-forming\nliquid by softening kinetic constraints, allowing them to be violated with a\nsmall finite rate. We demonstrate that this model supports a first-order\ndynamical (space-time) phase transition, similar to those observed with hard\nconstraints. In addition, we find that the first-order phase boundary in this\nsoftened model ends in a finite-temperature dynamical critical point, which we\nexpect to be present in natural systems. We discuss links between this critical\npoint and quantum phase transitions, showing that dynamical phase transitions\nin $d$ dimensions map to quantum transitions in the same dimension, and hence\nto classical thermodynamic phase transitions in $d+1$ dimensions. We make these\nlinks explicit through exact mappings between master operators, transfer\nmatrices, and Hamiltonians for quantum spin chains.",
        "category": "cond-mat"
    },
    {
        "text": "Pressure consistency for binary hard-sphere mixtures from an integral\n  equation approach: The site-site Ornstein-Zernike equation combined with the Verlet-modified\nbridge function has been applied to the binary hard sphere mixtures and\npressure consistency has been tested. An equation of state has been computed\nfor the case where a packing fraction is $\\eta = 0.49$, diameter ratios are\n$\\sigma_{2}/\\sigma_{1} = 0.3$ and $0.6$, and the mole fractions are $x_{1} =\n0.125, 0.5, 0.75$, and $1$. An excess chemical potential for each component has\nbeen obtained as well. Our findings for thermodynamic properties are in good\nagreement with available data in literature.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of Succinonitrile on Ion Transport in PEO-based Lithium Ion\n  Battery Electrolytes: We report the ion transport mechanisms in succinonitrile (SN) loaded solid\npolymer electrolytes containing polyethylene oxide (PEO) and dissolved lithium\nbis(trifluoromethane)sulphonamide (LiTFSI) salt using molecular dynamics\nsimulations. We investigated the effect of temperature and loading of SN on ion\ntransport and relaxation phenomenon in PEO-LiTFSI electrolytes. It is observed\nthat SN increases the ionic diffusivities in PEO-based solid polymer\nelectrolytes and makes them suitable for battery applications. Interestingly,\nthe diffusion coefficient of TFSI ions is an order of magnitude higher than the\ndiffusion coefficient of lithium ions across the range of temperatures and\nloadings integrated. By analyzing different relaxation timescales and examining\nthe underlying transport mechanisms in SN-loaded systems, we find that the\ndiffusivity of TFSI ions correlates excellently with the Li-TFSI ion-pair\nrelaxation timescales. In contrast, our simulations predict distinct transport\nmechanisms for Li-ions in SN-loaded PEO-LiTFSI electrolytes. Explicitly, the\ndiffusivity of lithium ions cannot be uniquely determined by the ion-pair\nrelaxation timescales but additionally depends on the polymer segmental\ndynamics. On the other hand, the SN loading induced diffusion coefficient at a\ngiven temperature does not correlate with either the ion-pair relaxation\ntimescales or the polymer segmental relaxation timescales.",
        "category": "cond-mat"
    },
    {
        "text": "Rethinking mean-field glassy dynamics and its relation with the energy\n  landscape: the awkward case of the spherical mixed p-spin model: The spherical p-spin model is not only a fundamental model in statistical\nmechanics of disordered system, but has recently gained popularity since many\nhard problems in machine learning can be mapped on it. Thus the study of the\nout of equilibrium dynamics in this model is interesting both for the glass\nphysics and for its implications on algorithms solving NP-hard problems. We\nrevisit the long-time limit of the out of equilibrium dynamics of mean-field\nspherical mixed p-spin models. We consider quenches (gradient descent dynamics)\nstarting from initial conditions thermalized at some temperature in the ergodic\nphase. We perform numerical integration of the dynamical mean-field equations\nof the model and we find an unexpected dynamical phase transition. Below an\nonset temperature, higher than the dynamical transition temperature, the\nasymptotic energy goes below the \"threshold energy\" of the dominant marginal\nminima of the energy function and memory of the initial condition is kept. This\nbehavior, not present in the pure spherical p-spin model, resembles closely the\none observed in simulations of glass-forming liquids. We then investigate the\nnature of the asymptotic dynamics, finding an aging solution that relaxes\ntowards deep marginal minima, evolving on a restricted marginal manifold.\nCareful analysis, however, rules out simple aging solutions. We compute the\nconstrained complexity in the aim of connecting the asymptotic solution to the\nenergy landscape.",
        "category": "cond-mat"
    },
    {
        "text": "Connectedness percolation of hard deformed rods: Nanofiller particles, such as carbon nanotubes or metal wires, are used in\nfunctional polymer composites to make them conduct electricity. They are often\nnot perfectly straight cylinders, but may be tortuous or exhibit kinks.\nTherefore we investigate the effect of shape deformations of the rodlike\nnanofillers on the geometric percolation threshold of the dispersion. We do\nthis by using connectedness percolation theory within a Parsons-Lee type of\napproximation, in combination with Monte Carlo integration for the average\noverlap volume in the isotropic fluid phase. We find that a deviation from a\nperfect rodlike shape has very little effect on the percolation threshold,\nunless the particles are strongly deformed. This demonstrates that idealized\nrod models are useful even for nanofillers that superficially seem imperfect.\nIn addition, we show that for small or moderate rod deformations, the universal\nscaling of the percolation threshold is only weakly affected by the precise\nparticle shape.",
        "category": "cond-mat"
    },
    {
        "text": "Optical Black-hole Analog Created by Topological Phase Transition with a\n  Long-lived Horizon: Hawking radiation, a manifestation of quantum field theory in curved\nspacetime, has stimulated extensive theoretical and experimental studies of\nvarious black-hole (BH) analogs. However, an undisputed confirmation of Hawking\nradiation remains elusive. One challenge is BH analog structures with\nlong-lived horizons are difficult to achieve. Here, we theoretically\ndemonstrate a new type of optical BH analog based on light cone evolution\nassociated with topological phase transition of Dirac cones. The transition\nfrom a type-II to type-I Dirac/Weyl cone creates an analogous curved spacetime\nthat crosses a type-III Dirac/Weyl cone, which affords a stationary\nconfiguration of long-lived event horizon. Photons tunneling through the\nhorizon emit a spectrum of Hawking radiation. As an example, we design a\nlaboratory version in an inhomogeneous two-dimensional graphyne-like\ntopological photonic lattice with a Hawking temperature of 0.14 mK.\nUnderstanding Hawking-like radiation in this unique topological BH is not only\nof fundamental interest in its own right but may also provide new hints to\ngravitational physics.",
        "category": "cond-mat"
    },
    {
        "text": "Defining Temperatures of Granular Powders Analogously with\n  Thermodynamics to Understand the Jamming Phenomena: For the purpose of applying laws or principles originated from thermal\nsystems to granular athermal systems, we may need to properly define the\ncritical temperature concept in granular powders. The conventional\nenvironmental temperature in thermal systems is too weak to drive movements of\nparticles in granular powders and cannot function as a thermal energy\nindicator. For maintaining the same functionality as in thermal systems, the\ntemperature in granular powders is defined analogously and uniformly in this\narticle. The newly defined granular temperature is utilized to describe and\nexplain one of the most important phenomena observed in granular powders, the\njamming transition, by introducing jamming temperature and jamming volume\nfraction concepts. The predictions from the equations of the jamming volume\nfractions for several cases like granular powders under shear or vibration are\nin line with experimental observations and empirical solutions in powder\nhandlings. The goal of this article is to establish similar concepts in\ngranular powders, allowing granular powders to be described with common laws or\nprinciples we are familiar with in thermal systems. Our intention is to build a\nbridge between thermal systems and granular powders to account for many\nsimilarities already found between these two systems.",
        "category": "cond-mat"
    },
    {
        "text": "Hyperuniformity of Maximally Random Jammed Packings of Hyperspheres\n  Across Spatial Dimensions: The maximally random jammed (MRJ) state is the most random configuration of\nstrictly jammed (mechanically rigid) nonoverlapping objects. MRJ packings are\nhyperuniform, meaning their long-wavelength density fluctuations are\nanomalously suppressed compared to typical disordered systems, i.e., their\nstructure factors $S(\\mathbf{k})$ tend to zero as the wavenumber $|\\mathbf{k}|$\ntends to zero. Here, we show that generating high-quality strictly jammed\nstates for space dimensions $d = 3,4,$ and $5$ is of paramount importance in\nensuring hyperuniformity and extracting precise values of the hyperuniformity\nexponent $\\alpha > 0$ for MRJ states, defined by the power-law behavior of\n$S(\\mathbf{k})\\sim|\\mathbf{k}|^{\\alpha}$ in the limit\n$|\\mathbf{k}|\\rightarrow0$. Moreover, we show that for fixed $d$ it is more\ndifficult to ensure jamming as the particle number $N$ increases, which results\nin packings that are nonhyperuniform. Free-volume theory arguments suggest that\nthe ideal MRJ state does not contain rattlers, which act as defects in\nnumerically generated packings. As $d$ increases, we find that the fraction of\nrattlers decreases substantially. Our analysis of the largest truly jammed\npackings suggests that the ideal MRJ packings for all dimensions $d\\geq3$ are\nhyperuniform with $\\alpha = d - 2$, implying the packings become more\nhyperuniform as $d$ increases. The differences in $\\alpha$ between MRJ packings\nand recently proposed Manna-class random close packed (RCP) states, which were\nreported to have $\\alpha = 0.25$ in $d=3$ and be nonhyperuniform ($\\alpha = 0$)\nfor $d = 4$ and $d = 5$, demonstrate the vivid distinctions between the\nlarge-scale structure of RCP and MRJ states in these dimensions. Our work\nclarifies the importance of the link between true jamming and hyperuniformity\nand motivates the development of an algorithm to produce rattler-free\nthree-dimensional MRJ packings.",
        "category": "cond-mat"
    },
    {
        "text": "Transport Properties of Multiple Quantum Dots Arranged in Parallel:\n  Results from the Bethe Ansatz: In this paper we analyze transport through a double dot system connected to\ntwo external leads. Imagining each dot possessing a single active level, we\nmodel the system through a generalization of the Anderson model. We argue that\nthis model is exactly solvable when certain constraints are placed upon the dot\nCoulomb charging energy, the dot-lead hybridization, and the value of the\napplied gate voltage. Using this exact solvability, we access the zero\ntemperature linear response conductance both in and out of the presence of a\nZeeman field. We are also able to study the finite temperature linear response\nconductance. We focus on universal behaviour and identify three primary\nfeatures in the transport of the dots: i) a so-called RKKY Kondo effect; ii) a\nstandard Kondo effect; and iii) interference phenomena leading to sharp\nvariations in the conductance including conductance zeros. We are able to use\nthe exact solvability of the dot model to characterize these phenomena\nquantitatively. While here we primarily consider a double dot system, the\napproach adopted applies equally well to N-dot systems.",
        "category": "cond-mat"
    },
    {
        "text": "Examination of the tradeoff between intrinsic and extrinsic properties\n  in the optimization of a modern internal tin Nb3Sn conductor: In modern Nb3Sn wires there is a fundamental compromise to be made between\noptimizing the intrinsic properties associated with the superfluid density in\nthe A15 phase (e.g. Tc, Hc, Hc2, all of which are composition dependent),\nmaximizing the quantity of A15 that can be formed from a given mixture of Nb,\nSn and Cu, minimizing the A15 composition gradients within each sub-element,\nwhile at the same time generating a high vortex pinning critical current\ndensity, Jc, by maximizing the grain boundary density with the additional\nconstraint of maintaining the RRR of the Cu stabilizer above 100. Here we study\nthese factors in a Ta-alloyed Restacked-Rod-Process (RRP) wire with ~70 microns\ndiameter sub-elements. Consistent with many earlier studies, maximum non-Cu\nJc(12T,4.2K) requires preventing A15 grain growth, rather than by optimizing\nthe superfluid density. In wires optimized for 12T, 4.2K performance, about 60%\nof the non-Cu cross-section is A15, 35% residual Cu and Sn core, and only 5% a\nresidual Nb7.5wt.%Ta diffusion barrier. The specific heat and chemical analyses\nshow that in this 60% A15 fraction there is a wide range of Tc and chemical\ncomposition that does diminish for higher heat treatment temperatures, which,\nhowever, are impractical because of the strong RRR degradation that occurs when\nonly about 2% of the A15 reaction front breaches the diffusion barrier. As this\nkind of Nb3Sn conductor design is being developed for sub-elements 1/2 the\npresent size, it is clear that better barriers are essential to allowing higher\ntemperature reactions with better intrinsic A15 properties. We present here\nmultiple and detailed intrinsic and extrinsic evaluations because we believe\nthat only such broad and quantitative descriptions are capable of accurately\ntracking the limitations of individual conductor designs where optimization\nwill always be a compromise between inherently conflicting goals",
        "category": "cond-mat"
    },
    {
        "text": "Orbital magnetization of correlated electrons with arbitrary band\n  topology: Spin-orbit coupling introduces chirality into electronic structure. This can\nhave profound effects on the magnetization induced by orbital motion of\nelectrons. Here we derive a formula for the orbital magnetization of\ninteracting electrons in terms of the full Green's function and vertex\nfunctions. The formula is applied within dynamical mean-field theory to the\nKane-Mele-Hubbard model that allows both topological and trivial insulating\nphases. We study the insulating and metallic phases in the presence of an\nexchange magnetic field. In the presence of interactions, the orbital\nmagnetization of the quantum spin Hall insulating phase with inversion symmetry\nis renormalized by the bulk quasi-particle weight. The orbital magnetization\nvanishes for the in-plane antiferromagnetic phase with trivial topology. In the\nmetallic phase, the enhanced effective spin-orbit coupling due to the\ninteraction sometimes leads to an enhancement of the orbital magnetization.\nHowever, at low doping, magnetization is suppressed at large interaction\nstrengths.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic molecular orbitals in MnSi: A large body of knowledge about magnetism is attained from models of\ninteracting spins, which usually reside on magnetic ions. Proposals beyond the\nionic picture are uncommon and seldom verified by direct observations in\nconjunction with microscopic theory. Here, using inelastic neutron scattering\nto study the itinerant near-ferromagnet MnSi, we find that the system's\nfundamental magnetic units are interconnected, extended molecular orbitals\nconsisting of three Mn atoms each, rather than individual Mn atoms. This result\nis further corroborated by magnetic Wannier orbitals obtained by ab initio\ncalculations. It contrasts the ionic picture with a concrete example, and\npresents a novel regime of the spin waves where the wavelength is comparable to\nthe spatial extent of the molecular orbitals. Our discovery brings important\ninsights into not only the magnetism of MnSi, but also a broad range of\nmagnetic quantum materials where structural symmetry, electron itinerancy and\ncorrelations act in concert.",
        "category": "cond-mat"
    },
    {
        "text": "Self-avoiding walks subject to a force: We prove some theorems about self-avoiding walks attached to an impenetrable\nsurface (i.e. positive walks) and subject to a force. Specifically we show the\nforce dependence of the free energy is identical when the force is applied at\nthe last vertex or at the top (confining) plane. We discuss the relevance of\nthis result to numerical results and to a recent result about convergence rates\nwhen the walk is being pushed towards the surface.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-polarized transport in II-VI magnetic resonant tunneling devices: We investigate electronic transport through II-VI semiconductor resonant\ntunneling structures containing diluted magnetic impurities. Due to the\nexchange interaction between the conduction electrons and the impurities, there\narises a giant Zeeman splitting in the presence of a moderately low magnetic\nfield. As a consequence, when the quantum well is magnetically doped the\ncurrent-voltage characteristics shows two peaks corresponding to transport for\neach spin channel. This behavior is experimentally observed and can be\nreproduced with a simple tunneling model. The model thus allows to analyze\nother configurations. First, we further increase the magnetic field, which\nleads to a spin polarization of the electronic current injected from the leads,\nthus giving rise to a relative change in the current amplitude. We demonstrate\nthat the spin polarization in the emitter can be determined from such a change.\nFurthermore, in the case of a magnetically doped injector our model shows a\nlarge increase in peak amplitude and a shift of the resonance to higher\nvoltages as the external field increases. We find that this effect arises from\na combination of giant Zeeman splitting, 3-D incident distribution and broad\nresonance linewidth.",
        "category": "cond-mat"
    },
    {
        "text": "Connection between matrix-product states and superposition of Bernoulli\n  shock measures: We consider a generalized coagulation-decoagulation system on a\none-dimensional discrete lattice with reflecting boundaries. It is known that a\nBernoulli shock measure with two shock fronts might have a simple random-walk\ndynamics, provided that some constraints on the microscopic reaction rates of\nthis system are fulfilled. Under these constraints the steady-state of the\nsystem can be written as a linear superposition of such shock measures. We show\nthat the coefficients of this expansion can be calculated using the\nfinite-dimensional representation of the quadratic algebra of the system\nobtained from a matrix-product approach.",
        "category": "cond-mat"
    },
    {
        "text": "eQE 2.0: Subsystem DFT Beyond GGA Functionals: By adopting a divide-and-conquer strategy, subsystem-DFT (sDFT) can\ndramatically reduce the computational cost of large-scale electronic structure\ncalculations. The key ingredients of sDFT are the nonadditive kinetic energy\nand exchange-correlation functionals which dominate it's accuracy. Even though,\nsemilocal nonadditive functionals find a broad range of applications, their\naccuracy is somewhat limited especially for those systems where achieving\nbalance between exchange-correlation interactions on one side and nonadditive\nkinetic energy on the other is crucial. In eQE 2.0, we improve dramatically the\naccuracy of sDFT simulations by (1) implementing nonlocal nonadditive kinetic\nenergy functionals based on the LMGP family of functionals; (2) adapting\nQuantum ESPRESSO's implementation of rVV10 and vdW-DF nonlocal\nexchange-correlation functionals to be employed in sDFT simulations; (3)\nimplementing \"deorbitalized\" meta GGA functionals (e.g., SCAN-L). We carefully\nassess the performance of the newly implemented tools on the S22-5 test set.\neQE 2.0 delivers excellent interaction energies compared to conventional\nKohn-Sham DFT and CCSD(T). The improved performance does not come at a loss of\ncomputational efficiency. We show that eQE 2.0 with nonlocal nonadditive\nfunctionals retains the same linear scaling behavior achieved in eQE 1.0 with\nsemilocal nonadditive functionals.",
        "category": "cond-mat"
    },
    {
        "text": "The Dynamics of Silica Melts under High Pressure: Mode-Coupling Theory\n  Results: The high-pressure dynamics of a computer-modeled silica melt is studied in\nthe framework of the mode-coupling theory of the glass transition (MCT) using\nstatic-structure input from molecular-dynamics (MD) computer simulation. The\ntheory reproduces the experimentally known viscosity minimum (diffusivity\nmaximum) as a function of density or pressure and explains it in terms of a\ncorresponding minimum in its critical temperature. This minimum arises from a\ngradual change in the equilibrium static structure which shifts from being\ndominated by tetrahedral ordering to showing the cageing known from\nhigh-density liquids. The theory is in qualitative agreement with computer\nsimulation results.",
        "category": "cond-mat"
    },
    {
        "text": "Capillary imbibition in a square tube: When a square tube is brought in contact with bulk liquid, the liquid wets\nthe corners of the tube, and creates finger-like wetted region. The wetting of\nthe liquid then takes place with the growth of two parts, the bulk part where\nthe cross section is entirely filled with the liquid and the finger part where\nthe cross section of the tube is partially filled. In the previous works, the\ngrowth of these two parts has been discussed separately. Here we conduct the\nanalysis by explicitly accounting for the coupling of the two parts. We propose\ncoupled equations for the liquid imbibition in both parts and show that (a) the\nlength of each part, $h_0$ and $h_1$, both increases in time $t$ following the\nLucas-Washburn's law, $h_0 \\sim t^{1/2}$ and $h_1 \\sim t^{1/2}$, but that (b)\nthe coefficients are different from those obtained in the previous analysis\nwhich ignored the coupling.",
        "category": "cond-mat"
    },
    {
        "text": "Evidence for 4e charge of Cooper quartets in a biased multi-terminal\n  graphene-based Josephson junction: In a Josephson junction (JJ), Cooper pairs are transported via Andreev bound\nstates (ABSs) between superconductors. The ABSs in the weak link of\nmulti-terminal (MT) JJs can coherently hybridize two Cooper pairs among\ndifferent superconducting electrodes, resulting in the Cooper quartet (CQ)\ninvolving four fermions entanglement. The energy spectrum of these CQ-ABS can\nbe controlled by biasing MT-JJs due to the AC Josephson effect. Here, using\ngate tunable four-terminal graphene JJs complemented with a flux loop, we\nconstruct CQs with a tunable spectrum. The critical quartet supercurrent\nexhibits magneto-oscillation associated with a charge of 4e; thereby presenting\nthe evidence for interference between entangled CQ-ABS. At a finite bias\nvoltage, we find the DC quartet supercurrent shows non-monotonic bias dependent\nbehavior, attributed to Landau-Zener transitions between different Floquet\nbands. Our experimental demonstration of coherent non-equilibrium CQ-ABS sets a\npath for design of artificial topological materials based on MT-JJs.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Monte Carlo Study on the Spin-1/2 Honeycomb Heisenberg Model\n  with Mixing Antiferromagnetic and Ferromagnetic Interactions in External\n  Magnetic Fields: The continuous imaginary-time quantum Monte Carlo method with the worm update\nalgorithm is applied to explore the ground state properties of the spin-1/2\nHeisenberg model with antiferromagnetic (AF) coupling $J>0$ and ferromagnetic\n(F) coupling $J^{\\prime}<0$ along zigzag and armchair directions, respectively,\non honeycomb lattice. It is found that by enhancing the F coupling $J^{\\prime}$\nbetween zigzag AF chains, the system is smoothly crossover from one-dimensional\nzigzag spin chains to a two-dimensional magnetic ordered state. In absence of\nan external field, the system is in a stripe order phase. In presence of\nuniform and staggered fields, the uniform and staggered out-of-plane\nmagnetizations appear while the stripe order keeps in $xy$ plane, and a\nsecond-order quantum phase transition (QPT) at a critical staggered field is\nobserved. The critical exponents of correlation length for QPTs induced by a\nstaggered field for the cases with $J>0$, $J^{\\prime}<0$ and $J<0$,\n$J^{\\prime}>0$ are obtained to be $\\nu=0.677(2)$ and $0.693(0)$, respectively,\nindicating that both cases belong to O(3) universality. The scaling behavior in\na staggered field is analyzed, and the ground state phase diagrams in the plane\nof coupling ratio and staggered field are presented for two cases. The\ntemperature dependence of susceptibility and specific heat of both systems in\nexternal magnetic fields is also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Operator-valued Riemann-Hilbert problem for correlation functions of the\n  XXZ spin chain: The generating functional of correlation functions for the XXZ spin chain is\nconsidered in the thermodynamic limit. We derive a system of integro-difference\nequations that prescribe this functional. On the basis of this system we\nestablish the operator-valued Riemann-Hilbert problem for correlation functions\nof the XXZ spin chain.",
        "category": "cond-mat"
    },
    {
        "text": "Decoding the Mechanisms of Reversibility Loss in Rechargeable Zinc-Air\n  Batteries: Attaining high reversibility of electrodes and electrolyte is essential for\nthe longevity of secondary batteries. Rechargeable zinc-air batteries (RZABs),\nhowever, encounter drastic irreversible changes in the zinc anodes and air\ncathodes during cycling. To uncover the mechanisms of reversibility loss in\nRZABs, we investigate the evolution of zinc anode, alkaline electrolyte, and\nair electrode through experiments and first-principles calculations. Morphology\ndiagrams of zinc anodes under versatile operating conditions reveal that the\nnano-sized mossy zinc dominates the later cycling stage. Such anodic change is\ninduced by the increased zincate concentration due to hydrogen evolution, which\nis catalyzed by the mossy structure and results in oxide passivation on\nelectrodes, and eventually leads to low true Coulombic efficiencies and short\nlifespans of batteries. Inspired by these findings, we finally present a novel\novercharge-cycling protocol to compensate the Coulombic efficiency loss caused\nby hydrogen evolution and significantly extend the battery life.",
        "category": "cond-mat"
    },
    {
        "text": "High-pressure synthesis and the enhancement of the superconducting\n  properties of FeSe0.5Te0.5: A series of FeSe0.5Te0.5 bulk samples have been prepared through the high gas\npressure and high-temperature synthesis (HP-HTS) method to optimize the growth\nconditions, for the first time and investigated for their superconducting\nproperties using structural, microstructure, transport, and magnetic\nmeasurements to reach the final conclusions. Ex-situ and in-situ processes are\nused to prepare bulk samples under a range of growth pressures using Ta-tube\nand without Tatube. The parent compound synthesized by convenient synthesis\nmethod at ambient pressure (CSP) exhibits a superconducting transition\ntemperature of 14.8 K. Our data demonstrate that the prepared FeSe0.5Te0.5\nsealed in a Ta-tube is of better quality than the samples without a Ta-tube,\nand the optimum growth conditions (500 MPa, 600{\\deg}C for 1 h) are favourable\nfor the development of the tetragonal FeSe0.5Te0.5 phase. The optimum bulk\nFeSe0.5Te0.5 depicts a higher transition temperature of 17.3 K and a high\ncritical current density of the order of >10^4 A/cm^2 at 0 T, which is improved\nover the entire magnetic field range and almost twice higher than the parent\ncompound prepared through CSP. Our studies confirm that the high-pressure\nsynthesis method is a highly efficient way to improve the superconducting\ntransition, grain connectivity, sample density, and also pinning properties of\na superconductor.",
        "category": "cond-mat"
    },
    {
        "text": "Doping Effect and Flux Pinning Mechanism of Nano-SiC Additions in MgB2\n  Strands: Superconducting MgB2 strands with nanometer-scale SiC additions have been\ninvestigated systematically using transport and magnetic measurements. A\ncomparative study of MgB2 strands with different nano-SiC addition levels has\nshown C-doping-enhanced critical current density Jc through enhancements in the\nupper critical field, Hc2, and decreased anisotropy. The critical current\ndensity and flux pinning force density obtained from magnetic measurements were\nfound to greatly differ from the values obtained through transport\nmeasurements, particularly with regards to magnetic field dependence. The\ndifferences in magnetic and transport results are largely attributed to\nconnectivity related effects. On the other hand, based on the scaling behavior\nof flux pinning force, there may be other effective pinning centers in MgB2\nstrands in addition to grain boundary pinning.",
        "category": "cond-mat"
    },
    {
        "text": "Geometric theory on the elasticity of bio-membranes: The purpose of this paper is to study the shapes and stabilities of\nbio-membranes within the framework of exterior differential forms. After a\nbrief review of the current status in theoretical and experimental studies on\nthe shapes of bio-membranes, a geometric scheme is proposed to discuss the\nshape equation of closed lipid bilayers, the shape equation and boundary\nconditions of open lipid bilayers and two-component membranes, the shape\nequation and in-plane strain equations of cell membranes with cross-linking\nstructures, and the stabilities of closed lipid bilayers and cell membranes.\nThe key point of this scheme is to deal with the variational problems on the\nsurfaces embedded in three-dimensional Euclidean space by using exterior\ndifferential forms.",
        "category": "cond-mat"
    },
    {
        "text": "Steady-state and quench dependent relaxation of a quantum dot coupled to\n  one-dimensional leads: We study the time evolution and steady state of the charge current in a\nsingle-impurity Anderson model, using matrix product states techniques. A\nnonequilibrium situation is imposed by applying a bias voltage across\none-dimensional tight-binding leads. Focusing on particle-hole symmetry, we\nextract current-voltage characteristics from universal low-bias up to high-bias\nregimes, where band effects start to play a dominant role. We discuss three\nquenches, which after strongly quench-dependent transients yield the same\nsteady-state current. Among these quenches we identify those favorable for\nextracting steady-state observables. The period of short-time oscillations is\nshown to compare well to real-time renormalization group results for a simpler\nmodel of spinless fermions. We find indications that many-body effects play an\nimportant role at high-bias voltage and finite bandwidth of the metallic leads.\nThe growth of entanglement entropy after a certain time scale (proportional to\nthe inverse of Delta) is the major limiting factor for calculating the time\nevolution. We show that the magnitude of the steady-state current positively\ncorrelates with entanglement entropy. The role of high-energy states for the\nsteady-state current is explored by considering a damping term in the time\nevolution.",
        "category": "cond-mat"
    },
    {
        "text": "Kinetics of inherent processes counteracting crystallization in\n  supercooled monatomic liquid: Crystallization of supercooled liquids is mainly determined by two competing\nprocesses associated with the transition of particles (atoms) from liquid phase\nto crystalline one and, vice versa, with the return of particles from\ncrystalline phase to liquid one. The quantitative characteristics of these\nprocesses are the so-called attachment rate $g^{+}$ and the detachment rate\n$g^{-}$, which determine how particles change their belonging from one phase to\nanother. In the present study, a {\\it correspondence rule} between the rates\n$g^{+}$ and $g^{-}$ as functions of the size $N$ of growing crystalline nuclei\nis defined for the first time. In contrast to the well-known detailed balance\ncondition, which relates $g^{+}(N)$ and $g^{-}(N)$ at $N=n_c$ (where $n_c$ is\nthe critical nucleus size) and is satisfied only at the beginning of the\nnucleation regime, the found {\\it correspondence rule} is fulfilled at all the\nmain stages of crystallization kinetics (crystal nucleation, growth and\ncoalescence). On the example of crystallizing supercooled Lennard-Jones liquid,\nthe rate $g^{-}$ was calculated for the first time at different supercooling\nlevels and for the wide range of nucleus sizes $N\\in[n_c;\\,40\\,n_c]$. It was\nfound that for the whole range of nucleus sizes, the detachment rate $g^{-}$ is\nonly $\\approx2$\\% less than the attachment rate $g^{+}$. This is direct\nevidence that the role of the processes that counteract crystallization remains\nsignificant at all the stages of crystallization. Based on the obtained\nresults, a kinetic equation was formulated for the time-dependent distribution\nfunction of the nucleus sizes, that is an alternative to the well-known kinetic\nBecker-D\\\"{o}ring-Zeldovich-Frenkel equation.",
        "category": "cond-mat"
    },
    {
        "text": "Exceptional point description of one-dimensional chiral topological\n  superconductors/superfluids in BDI class: We show that certain singularities of the Hamiltonian in the complex wave\nvector space can be used to identify topological quantum phase transitions for\n$1D$ chiral topological superconductors/superfluids in the BDI class. These\nsingularities fall into the category of the so-called exceptional points\n($EP$'s) studied in the context of non-Hermitian Hamiltonians describing open\nquantum systems. We also propose a generic formula in terms of the properties\nof the $EP$'s to quantify the exact number of Majorana zero modes in a\nparticular chiral topological superconducting phase, given the values of the\nparameters appearing in the Hamiltonian. This formula serves as an alternative\nto the familiar integer ($\\mathbb{Z}$) winding number invariant characterizing\ntopological superconductor/superfluid phases in the chiral BDI class.",
        "category": "cond-mat"
    },
    {
        "text": "Twisted bilayer blue phosphorene: A direct band gap semiconductor: We report that two rotated layers of blue phosphorene behave as a direct band\ngap semiconductor. The optical spectrum shows absorption peaks in the visible\nregion of the spectrum and in addition the energy of these peaks can be tuned\nwith the rotational angle. These findings makes twisted bilayer blue\nphosphorene a strong candidate as a solar cell or photodetection device. Our\nresults are based on ab initio calculations of several rotated blue phosphorene\nlayers.",
        "category": "cond-mat"
    },
    {
        "text": "Bulk Geometry of the Many Body Localized Phase from Wilson-Wegner Flow: Tensor networks are a powerful formalism for transforming one set of degrees\nof freedom to another. They have been heavily used in analyzing the geometry of\nbulk/boundary correspondence in conformal field theories. Here we develop a\ntensor-network version of the Wilson-Wegner Renormalization Group Flow\nequations to efficiently generate a unitary tensor network which diagonalizes\nmany-body localized Hamiltonians. Treating this unitary tensor network as a\nbulk geometry, we find this emergent geometry corresponds to the shredded\nhorizon picture: the circumference of the network shrinks exponentially with\ndistance into the bulk, with spatially distant points being largely\ndisconnected.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of an optical non-Fermi-liquid behavior in the heavy fermion\n  state of YbRh$_{2}$Si$_{2}$: We report far-infrared optical properties of YbRh$_{2}$Si$_{2}$ for photon\nenergies down to 2 meV and temperatures 0.4 -- 300 K. In the coherent heavy\nquasiparticle state, a linear dependence of the low-energy scattering rate on\nboth temperature and photon energy was found. We relate this distinct dynamical\nbehavior different from that of Fermi liquid materials to the non-Fermi liquid\nnature of YbRh$_{2}$Si$_{2}$ which is due to its close vicinity to an\nantiferromagnetic quantum critical point.",
        "category": "cond-mat"
    },
    {
        "text": "Faulty evidence for superconductivity in ac magnetic susceptibility of\n  sulfur hydride under pressure: It is generally believed that sulfur hydride under high pressure is a high\ntemperature superconductor. In National Science Review 6, 713 (2019) Huang and\ncoworkers reported detection of superconductivity in sulfur hydride through a\nhighly sensitive ac magnetic susceptibility technique and an unambiguous\ndetermination of the superconducting phase diagram. In this paper we present\nevidence showing that the experimental results reported in that paper do not\nsupport the conclusion that sulfur hydride is a superconductor.",
        "category": "cond-mat"
    },
    {
        "text": "Theory of Superfluids with Population Imbalance: Finite Temperature and\n  BCS-BEC Crossover Effects: In this paper we present a very general theoretical framework for addressing\nfermionic superfluids over the entire range of BCS to Bose Einstein\ncondensation (BEC) crossover in the presence of population imbalance or spin\npolarization. Our emphasis is on providing a theory which reduces to the\nstandard zero temperature mean field theories in the literature, but\nnecessarily includes pairing fluctuation effects at non-zero temperature within\na consistent framework. Physically, these effects are associated with the\npresence of pre-formed pairs (or a fermionic pseudogap) in the normal phase,\nand pair excitations of the condensate, in the superfluid phase. We show how\nthis finite $T$ theory of fermionic pair condensates bears many similarities to\nthe condensation of point bosons. In the process we examine three different\ntypes of condensate: the usual breached pair or Sarma phase and both the one\nand two plane wave Larkin- Ovchinnikov, Fulde-Ferrell (LOFF) states. The last\nof these has been discussed in the literature albeit only within a\nLandau-Ginzburg formalism, generally valid near $T_c$. Here we show how to\narrive at the two plane wave LOFF state in the ground state as well as at\ngeneral temperature $T$.",
        "category": "cond-mat"
    },
    {
        "text": "Conductance in strongly correlated 1D systems: Real-Time Dynamics in\n  DMRG: A new method to perform linear and finite bias conductance calculations in\none dimensional systems based on the calculation of real time evolution within\nthe Density Matrix Renormalization Group (DMRG) is presented. We consider a\nsystem of spinless fermions consisting of an extended interacting nanostructure\nattached to non-interacting leads. Results for the linear and finite bias\nconductance through a seven site structure with weak and strong\nnearest-neighbor interactions are presented. Comparison with exact\ndiagonalization results in the non-interacting limit serve as verification of\nthe accuracy of our approach. Our results show that interaction effects lead to\nan energy dependent self energy in the differential conductance.",
        "category": "cond-mat"
    },
    {
        "text": "Thermally Activated Motion of Sodium Cations in Insulating Parent\n  Low-Silica X Zeolite: We report a $^{23}$Na spin-lattice relaxation rate, $T_1^{-1}$, in low-silica\nX zeolite. $T_1^{-1}$ follows multiple BPP-type behavior as a result of thermal\nmotion of sodium cations in insulating material. The estimated lowest\nactivation energy of 15~meV is much lower than 100~meV observed previously for\nsodium motion in heavily Na-loaded samples and is most likely attributed to\nshort-distance jumps of sodium cations between sites within the same supercage.",
        "category": "cond-mat"
    },
    {
        "text": "Nature of order from random two-body interactions: We investigate the origin of order in the low-lying spectra of many-body\nsystems with random two-body interactions. Our study based both on analytical\nas well as on numerical arguments shows that except for the most $J$-stretched\nstates, the ground states in the higher $J$-sectors are more orderly and\ndevelop larger energy gaps than the ones in the J=0-sector. Due to different\ncharacteristic energy scales in different $J$-sectors the J=0 ground states may\npredominate only when all the states are taken together.",
        "category": "cond-mat"
    },
    {
        "text": "Detailed magneto-heat capacity analysis of SnAs topological\n  superconductor: In this article, we report magneto-heat capacity analysis of superconducting\nSnAs, which is characterized through X-ray diffraction (XRD), X-ray\nphotoelectron spectroscopy (XPS), and magneto-transport measurements. The\nstudied SnAs superconductor evidenced the presence of superconductivity at\naround 4K, and the same is seen to persist up to an applied field of 250Oe. The\nbulk nature of superconductivity is determined through AC susceptibility along\nwith heat capacity measurements. Magneto-heat capacity measurements show SnAs\nto be a fully gapped s wave superconductor. This finding is well supported by\ncalculated superconducting physical parameters. Further, the calculation of the\nresidual Sommerfeld coefficient at different fields confirms node-less\nsuperconductivity in SnAs.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical generation of skyrmion and bimeron crystals by a circularly\n  polarized electric field in frustrated magnets: A skyrmion crystal (SkX) has attracted much attention in condensed matter\nphysics, since topologically nontrivial structures induce fascinating physical\nphenomena. The SkXs have been experimentally observed in a variety of\nmaterials, where the Zeeman coupling to the static magnetic field plays an\nimportant role in the formation of the SkXs. In this study, we theoretically\npropose another route to generate the SkXs by using a circularly polarized\nelectric field. We investigate a non-equilibrium steady state in a classical\nfrustrated Heisenberg magnet under the circularly polarized electric field,\nwhere the electric field is coupled to the electric polarization via the\nspin-current mechanism. By numerically solving the Landau-Lifshitz-Gilbert\nequation at zero temperature, we show that the electric field radiation\ngenerates a SkX with a high topological number in the high-frequency regime,\nwhere the sign of the skyrmion number is fixed to be negative (positive) under\nthe left (right) circularly polarized field. The intense electric field melts\nthese SkXs and generates isolated skyrmions. We clarify that the microscopic\norigin is effective electric-field-induced three-spin interactions by adopting\nthe high-frequency expansion in the Floquet formalism. Furthermore, we find\nthat the electric field radiation generates another type of SkXs, a bimeron\ncrystal, in the low-frequency regime. Our results provide a way to generate the\nSkXs and control the topology by the circularly polarized electric field.",
        "category": "cond-mat"
    },
    {
        "text": "Second sound resonators and tweezers as vorticity or velocity probes :\n  fabrication, model and method: An analytical model of open-cavity second sound resonators is presented and\nvalidated against simulations and experiments in superfluid helium using a new\nresonator design that achieves unprecedented resolution. The model incorporates\ndiffraction, geometrical misalignments, and flow through the cavity, and is\nvalidated using cavities with aspect ratios close to unity, operated up to\ntheir 20th resonance in superfluid helium.An important finding of this study is\nthat resonators can be optimized to selectively sense either the quantum vortex\ndensity carried by the throughflow -- as typically done in the literature -- or\nthe mean velocity of the throughflow. We propose two velocity probing methods:\none that takes advantage of geometrical misalignments between the tweezers\nplates, and another that drives the resonator non-linearly, beyond a threshold\nthat results in the self-sustainment of a vortex tangle within the cavity.A new\nmathematical treatment of the resonant signal is proposed to adequately filter\nout parasitic signals, such as temperature and pressure drift, and accurately\nseparate the quantum vorticity signal. This elliptic method consists in a\ngeometrical projection of the resonance in the inverse complex plane. Its\neffectiveness is demonstrated over a wide range of operating conditions.The\nresonator model and elliptic method are being utilized to characterize a new\ndesign of second-sound resonator with high resolution thanks to miniaturization\nand design optimization. These second-sound tweezers are capable of providing\ntime-space resolved information similar to classical local probes in\nturbulence, down to sub-millimeter and sub-millisecond scales. The principle,\ndesign, and micro-fabrication of second sound tweezers are being presented in\ndetail, along with their potential for exploring quantum turbulence.",
        "category": "cond-mat"
    },
    {
        "text": "Large fluctuations of the KPZ equation in a half-space: We investigate the short-time regime of the KPZ equation in $1+1$ dimensions\nand develop a unifying method to obtain the height distribution in this regime,\nvalid whenever an exact solution exists in the form of a Fredholm Pfaffian or\ndeterminant. These include the droplet and stationary initial conditions in\nfull space, previously obtained by a different method. The novel results\nconcern the droplet initial condition in a half space for several Neumann\nboundary conditions: hard wall, symmetric, and critical. In all cases, the\nheight probability distribution takes the large deviation form $P(H,t) \\sim\n\\exp( - \\Phi(H)/\\sqrt{t})$ for small time. We obtain the rate function\n$\\Phi(H)$ analytically for the above cases. It has a Gaussian form in the\ncenter with asymmetric tails, $|H|^{5/2}$ on the negative side, and $H^{3/2}$\non the positive side. The amplitude of the left tail for the half-space is\nfound to be half the one of the full space. As in the full space case, we find\nthat these left tails remain valid at all times. In addition, we present here\n(i) a new Fredholm Pfaffian formula for the solution of the hard wall boundary\ncondition and (ii) two Fredholm determinant representations for the solutions\nof the hard wall and the symmetric boundary respectively.",
        "category": "cond-mat"
    },
    {
        "text": "Probing superfluid $^4\\mathrm{He}$ with high-frequency nanomechanical\n  resonators down to $\\mathrm{mK}$ temperatures: Superfluids, such as superfluid $^3\\mathrm{He}$ and $^4\\mathrm{He}$, exhibit\na broad range of quantum phenomena and excitations which are unique to these\nsystems. Nanoscale mechanical resonators are sensitive and versatile force\ndetectors with the ability to operate over many orders of magnitude in damping.\nUsing nanomechanical-doubly clamped beams of extremely high quality factors\n($Q>10^6$), we probe superfluid $^4\\mathrm{He}$ from the superfluid transition\ntemperature down to $\\mathrm{mK}$ temperatures at frequencies up to $11.6 \\,\n\\mathrm{MHz}$. Our studies show that nanobeam damping is dominated by\nhydrodynamic viscosity of the normal component of $^4\\mathrm{He}$ above\n$1\\,\\mathrm{K}$. In the temperature range $0.3-0.8\\,\\mathrm{K}$, the ballistic\nquasiparticles (phonons and rotons) determine the beams' behavior. At lower\ntemperatures, damping saturates and is determined either by magnetomotive\nlosses or acoustic emission into helium. It is remarkable that all these\ndistinct regimes can be extracted with just a single device, despite damping\nchanging over six orders of magnitude.",
        "category": "cond-mat"
    },
    {
        "text": "KMC-MD Investigations of Hyperthermal Copper Deposition on Cu(111): Detailed KMC-MD (kinetic Monte Carlo-molecular dynamics) simulations of\nhyperthermal energy (10-100 eV) copper homoepitaxy have revealed a re-entrant\nlayer-by-layer growth mode at low temperatures (50K) and reasonable fluxes (1\nML/s). This growth mode is the result of atoms with hyperthermal kinetic\nenergies becoming inserted into islands when the impact site is near a step\nedge. The yield for atomic insertion as calculated with molecular dynamics near\n(111) step edges reaches a maxima near 18 eV. KMC-MD simulations of growing\nfilms and a minima in the RMS roughness as a function of energy near 25 eV. We\nfind that the RMS roughness saturates just beyond 0.5 ML of coverage in films\ngrown with energies greater than 25 eV due to the onset of adatom-vacancy\nformation near 20 eV. Adatom-vacancy pairs increase the island nuclei density\nand the step edge density which increases the number of sites available to\ninsert atoms. Smoothest growth in this regime is achieved by maximizing island\nand step edge densities, which consequently reverses the traditional roles of\ntemperature and flux: low temperatures and high fluxes produce the smoothest\nsurfaces in these films. Dramatic increases in island densities are found to\npersist at room temperature,where island densities increase an order of\nmagnitude from 20 to 150 eV.",
        "category": "cond-mat"
    },
    {
        "text": "Significant enhancement of ferromagnetism in Zn$_{1-x}$Cr$_{x}$Te doped\n  with iodine as an n-type dopant: The effect of additional doping of charge impurities was investigated in a\nferromagnetic semiconductor Zn$_{1-x}$Cr$_{x}$Te. It was found that the doping\nof iodine, which is expected to act as an n-type dopant in ZnTe, brought about\na drastic enhancement of the ferromagnetism in Zn$_{1-x}$Cr$_{x}$Te while the\ngrown films remained electrically insulating. In particular, at a fixed Cr\ncomposition of x = 0.05, the ferromagnetic transition temperature Tc increased\nup to 300K at maximum due to the iodine doping from Tc = 30K of the undoped\ncounterpart, while the ferromagnetism disappeared due to the doping of nitrogen\nas a p-type dopant. The observed systematic correlation of ferromagnetism with\nthe doping of charge impurities of both p- and n-type, suggesting a key role of\nthe position of Fermi level within the impurity d-state, is discussed on the\nbasis of the double exchange interaction as a mechanism of ferromagnetism in\nthis material.",
        "category": "cond-mat"
    },
    {
        "text": "Proposal for a two-channel quantum dot setup: Prediction for the\n  capacitance lineshape: We have made a detailed proposal for a two-channel quantum dot setup. The\nenergy scales in the problem are such that we are able to make connection with\nthe two-channel Anderson model, which, in spite of being well-known in the\ncontext of heavy-Fermion systems remained theoretically elusive until recently\nand lacked a mesoscopic realization. Verification of our precise and robust\npredictions for the differential capacitance lineshape of the dot will provide\nan experimental signature of the two-channel behavior.",
        "category": "cond-mat"
    },
    {
        "text": "Universal Behavior of Entanglement in 2D Quantum Critical Dimer Models: We examine the scaling behavior of the entanglement entropy for the 2D\nquantum dimer model (QDM) at criticality and derive the universal finite\nsub-leading correction $\\gamma_{QCP}$. We compute the value of $\\gamma_{QCP}$\nwithout approximation working directly with the wave function of a generalized\n2D QDM at the Rokhsar-Kivelson QCP in the continuum limit. Using the replica\napproach, we construct the conformal boundary state corresponding to the cyclic\nidentification of $n$-copies along the boundary of the observed region. We find\nthat the universal finite term is $\\gamma_{QCP}=\\ln R-1/2$ where $R$ is the\ncompactification radius of the bose field theory quantum Lifshitz model, the\neffective field theory of the 2D QDM at quantum criticality. We also\ndemonstrated that the entanglement spectrum of the critical wave function on a\nlarge but finite region is described by the characters of the underlying\nconformal field theory. It is shown that this is formally related to the\nproblems of quantum Brownian motion on $n$-dimensional lattices or equivalently\na system of strings interacting with a brane containing a background\nelectromagnetic field and can be written as an expectation value of a vertex\noperator.",
        "category": "cond-mat"
    },
    {
        "text": "Semiclassical analysis of edge state energies in the integer quantum\n  Hall effect: Analysis of edge-state energies in the integer quantum Hall effect is carried\nout within the semiclassical approximation. When the system is wide so that\neach edge can be considered separatly, this problem is equivalent to that of a\none dimensional harmonic oscillator centered at x=x_c and an infinite wall at\nx=0, and appears in numerous physical contexts. The eigenvalues E_n(x_c) for a\ngiven quantum number n are solutions of the equation S(E,x_c)=\\pi [n+\n\\gamma(E,x_c)] where S is the WKB action and 0<\\gamma<1 encodes all the\ninformation on the connection procedure at the turning points.\n  A careful implication of the WKB connection formulae results in an excellent\napproximation to the exact energy eigenvalues. The dependence of \\gamma\n[E_n(x_c),x_c] \\equiv \\gamma_c (x_c) on x_c is analyzed between its two extreme\nvalues 1/2 as x_c goes to -infinity far inside the sample and 3/4 as x_c goes\nto infinity far outside the sample. The edge-state energies E_n(x_c) obey an\nalmost exact scaling law of the form E_n(x_c)=4 [n+\\gamma_n(x_c)] f(x_c/4 n +3)\nand the scaling function f(y) is explicitly elucidated",
        "category": "cond-mat"
    },
    {
        "text": "Thermodynamics and criticality of su($m$) spin chains of Haldane-Shastry\n  type: We study the thermodynamics and critical behavior of su($m$) spin chains of\nHaldane-Shastry type at zero chemical potential, both in the $A_{N-1}$ and\n$BC_N$ cases. We evaluate in closed form the free energy per spin for arbitrary\nvalues of $m$, from which we derive explicit formulas for the energy, entropy\nand specific heat per spin. In particular, we find that the specific heat\nfeatures a single Schottky peak, whose temperature is well approximated for\n$m\\lesssim10$ by the corresponding temperature for an $m$-level system with\nuniformly spaced levels. We show that at low temperatures the free energy per\nspin of the models under study behaves as that of a one-dimensional conformal\nfield theory with central charge $c=m-1$ (with the only exception of the\nFrahm-Inozemtsev chain with zero value of its parameter). However, from a\ndetailed study of the ground state degeneracy and the low-energy excitations,\nwe conclude that these models are only critical in the antiferromagnetic case,\nwith a few exceptions that we fully specify.",
        "category": "cond-mat"
    },
    {
        "text": "Damage in porous media due to salt crystallization: We investigate the origins of salt damage in sandstones for the two most\ncommon salts: sodium chloride and sulfate. The results show that the observed\ndifference in damage between the two salts is directly related to the kinetics\nof crystallization and the interfacial properties of the salt solutions and\ncrystals with respect to the stone. We show that, for sodium sulfate, the\nexistence of hydrated and anhydrous crystals and specifically their dissolution\nand crystallization kinetics are responsible for the damage. Using magnetic\nresonance imaging and optical microscopy we show that when water imbibes sodium\nsulfate contaminated sandstones, followed by drying at room temperature, large\ndamage occurs in regions where pores are fully filled with salts. After partial\ndissolution, anhydrous sodium sulfate salt present in these regions gives rise\nto a very rapid growth of the hydrated phase of sulfate in the form of clusters\nthat form on or close to the remaining anhydrous microcrystals. The rapid\ngrowth of these clusters generates stresses in excess of the tensile strength\nof the stone leading to the damage. Sodium chloride only forms anhydrous\ncrystals that consequently do not cause damage in the experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Interstitial Transition Metal Doping in Hydrogen Saturated Silicon\n  Nanowires: We report a first principles systematic study of atomic, electronic, and\nmagnetic properties of hydrogen saturated silicon nanowires (H-SiNW) which are\ndoped by transition metal (TM) atoms placed at various interstitial sites. Our\nresults obtained within the conventional GGA+U approach have been confirmed\nusing an hybrid functional. In order to reveal the surface effects we examined\nthree different possible facets of H-SiNW along [001] direction with a diameter\nof ~2nm. The energetics of doping and resulting electronic and magnetic\nproperties are examined for all alternative configurations. We found that\nexcept Ti, the resulting systems have magnetic ground state with a varying\nmagnetic moment. While H-SiNWs are initially non-magnetic semiconductor, they\ngenerally become ferromagnetic metal upon TM doping. Even they posses\nhalf-metallic behavior for specific cases. Our results suggest that H-SiNWs can\nbe functionalized by TM impurities which would lead to new electronic and\nspintronic devices at nanoscale.",
        "category": "cond-mat"
    },
    {
        "text": "Theorems on ground-state phase transitions in Kohn-Sham models given by\n  the Coulomb density functional: Some theorems on derivatives of the Coulomb density functional with respect\nto the coupling constant $\\lambda$ are given. Consider an electron density\n$n_{GS}({\\bf r})$ given by a ground state. A model Fermion system with the\nreduced coupling constant, $\\lambda<1$, is defined to reproduce $n_{GS}({\\bf\nr})$ and the ground state energy. Fixing the charge density, possible phase\ntransitions as level crossings detected in a value of the reduced density\nfunctional happen only at discrete points along the $\\lambda$ axis. If the\ndensity is $v$-representable also for $\\lambda<1$, accumulation of phase\ntransition points is forbidden when $\\lambda\\rightarrow 1$. Relevance of the\ntheorems for the multi-reference density functional theory is discussed.",
        "category": "cond-mat"
    },
    {
        "text": "The stochastic Gross-Pitaevskii equation: We show how to adapt the ideas of local energy and momentum conservation in\norder to derive modifications to the Gross-Pitaevskii equation which can be\nused phenomenologically to describe irreversible effects in a Bose-Einstein\ncondensate. Our approach involves the derivation of a simplified quantum\nkinetic theory, in which all processes are treated locally. It is shown that\nthis kinetic theory can then be transformed into a number of phase-space\nrepresentations, of which the Wigner function description, although\napproximate, is shown to be the most advantageous. In this description, the\nquantum kinetic master equation takes the form of a GPE with noise and damping\nadded according to a well-defined prescription--an equation we call the\nstochastic GPE. From this, a very simplified description we call the\nphenomenological growth equation can be derived. We use this equation to study\ni) the nucleation and growth of vortex lattices, and ii) nonlinear losses in a\nhydrogen condensate, which it is shown can lead to a curious instability\nphenomenon.",
        "category": "cond-mat"
    },
    {
        "text": "Surface plasmons for doped graphene: Within the Dirac model for the electronic excitations of graphene, we\ncalculate the full polarization tensor with finite mass and chemical potential.\nIt has, besides the (00)-component, a second form factor, which must be\naccounted for. We obtain explicit formulas for both form factors and for the\nreflection coefficients. Using these, we discuss the regions in the\nmomentum-frequency plane where plasmons may exist and give numeric solutions\nfor the plasmon dispersion relations. It turns out that plasmons exist for\nboth, TE and TM polarizations over the whole range of the ratio of mass to\nchemical potential, except for zero chemical potential, where only a TE plasmon\nexists.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamics of fully coupled rotators with unimodal and bimodal frequency\n  distribution: We analyze the synchronization transition of a globally coupled network of N\nphase oscillators with inertia (rotators) whose natural frequencies are\nunimodally or bimodally distributed. In the unimodal case, the system exhibits\na discontinuous hysteretic transition from an incoherent to a partially\nsynchronized (PS) state. For sufficiently large inertia, the system reveals the\ncoexistence of a PS state and of a standing wave (SW) solution. In the bimodal\ncase, the hysteretic synchronization transition involves several states.\nNamely, the system becomes coherent passing through traveling waves (TWs), SWs\nand finally arriving to a PS regime. The transition to the PS state from the SW\noccurs always at the same coupling, independently of the system size, while its\nvalue increases linearly with the inertia. On the other hand the critical\ncoupling required to observe TWs and SWs increases with N suggesting that in\nthe thermodynamic limit the transition from incoherence to PS will occur\nwithout any intermediate states. Finally a linear stability analysis reveals\nthat the system is hysteretic not only at the level of macroscopic indicators,\nbut also microscopically as verified by measuring the maximal Lyapunov\nexponent.",
        "category": "cond-mat"
    },
    {
        "text": "Resistive and rectifying effects of pulling gold atoms at thiol-gold\n  nano-contacts: We investigate, by means of first-principles calculations, structural and\ntransport properties of junctions made of symmetric dithiolated molecules\nplaced between Au electrodes. As the electrodes are pulled apart, we find that\nit becomes energetically favorable that Au atoms migrate to positions between\nthe electrode surface and thiol terminations, with junction structures\nalternating between symmetric and asymmetric. As a result, the calculated\n$\\emph{IV}$ curves alternate between rectifying and non-rectifying behaviors as\nthe electrodes are pulled apart, which is consistent with recent experimental\nresults.",
        "category": "cond-mat"
    },
    {
        "text": "Thin Film Growth of Heavy Fermion Chiral Magnet YbNi3Al9: We grew thin films of a heavy fermion chiral magnet YbNi$_3$Al$_9$ by using\nmolecular beam epitaxy. They were grown on $c$-plane sapphire substrates under\nultra-high vacuum while maintaining a deposition rate at a stoichiometric ratio\namong Yb, Ni, and Al. The resulting thin films contain epitaxial grains with a\n$c$ axis parallel to the substrate surface: The YbNi$_3$Al$_9$ $c$ axis is\nparallel to the sapphire $b$ or $a$ axis. The temperature dependence of the\nresistivity exhibits a typical feature of a dense Kondo system with a broad\nshoulder structure at $\\sim$40\\,K, as well as a kink as a signature of the\nchiral helimagnetic ordering at 3.6\\,K. These features are consistent with\nthose previously observed in bulk samples. The shift in the kink associated\nwith the field-induced phase transition is found in the magnetoresistance\ncurves under a magnetic field applied in the direction perpendicular to the\n$c$-axis. The magnetic phase diagram well reproduces that for the bulk\ncrystals, implying that the chiral soliton lattice phase arises under magnetic\nfields, even in thin films.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Confined Stark Effect in Wide Parabolic Quantum Wells: We show how to compute the optical functions of Wide Parabolic Quantum Wells\n(WPQWs) exposed to uniform electric F applied in the growth direction, in the\nexcitonic energy region. The effect of the coherence between the electron-hole\npair and the electromagnetic field of the propagating wave including the\nelectron-hole screened Coulomb potential is adopted, and the valence band\nstructure is taken into account in the cylindrical approximation. The role of\nthe interaction potential and of the applied electric field, which mix the\nenergy states according to different quantum numbers and create symmetry\nforbidden transitions, is stressed. We use the Real Density Matrix Approach\n(RDMA) and an effective e-h potential, which enable to derive analytical\nexpressions for the WPQWs electrooptical functions. Choosing the\nsusceptibility, we performed numerical calculations appropriate to a\nGaAs/GaAlAs WPQWs. We have obtained a red shift of the absorption maxima\n(Quantum Confined Stark Effect), asymmetric upon the change of the direction of\nthe applied field (F -> -F), parabolic for the ground state and strongly\ndependent on the confinement parameters (the QWs sizes), changes in the\noscillator strengths, and new peaks related to the states with different parity\nfor electron and hole.",
        "category": "cond-mat"
    },
    {
        "text": "Lanthanide molecular nanomagnets as probabilistic bits: Over the decades, the spin dynamics of a large set of lanthanide complexes\nhave been explored. Lanthanide-based molecular nanomagnets are bistable spin\nsystems, generally conceptualized as classical bits, but many lanthanide\ncomplexes have also been presented as candidate quantum bits (qubits). Here we\noffer a third alternative and model them as probabilistic bits (p-bits), where\ntheir stochastic behavior constitutes a computational resource instead of a\nlimitation. We present a modelling tool for molecular spin p-bits, we\ndemonstrate its capability to simulate bulk magnetic relaxation data and ac\nexperiments and to simulate a minimal p-bit network under realistic conditions.\nFinally, we go back to a recent systematic data gathering and screen the best\nlanthanide complexes for p-bit behavior, lay out the performance of the\ndifferent lanthanide ions and chemical families and offer some chemical design\nconsiderations.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic-Field-Induced 4f-Octupole in CeB6 Probed by Resonant X-ray\n  Diffraction: CeB6, a typical Gamma_8-quartet system, exhibits a mysterious\nantiferroquadrupolar ordered phase in magnetic fields, which is considered as\noriginating from the T_{xyz}-type magnetic octupole moment induced by the\nfield. By resonant x-ray diffraction in magnetic fields, we have verified that\nthe T_{xyz}-type octupole is indeed induced in the 4f-orbital of Ce with a\npropagation vector (1/2, 1/2, 1/2), thereby supporting the theory. We observed\nan asymmetric field dependence of the intensity for an electric quadrupole (E2)\nresonance when the field was reversed, and extracted a field dependence of the\noctupole by utilizing the interference with an electric dipole (E1) resonance.\nThe result is in good agreement with that of the NMR-line splitting, which\nreflects the transferred hyperfine field at the Boron nucleus from the\nanisotropic spin distribution of Ce with an O_{xy}-type quadrupole. The\nfield-reversal method used in the present study opens up the possibility of\nbeing widely applied to other multipole ordering systems such as NpO2,\nCe_{x}La_{1-x}B_{6}, SmRu_{4}P_{12}, and so on.",
        "category": "cond-mat"
    },
    {
        "text": "The type II Weyl semimetals at low temperatures: chiral anomaly, elastic\n  deformations, zero sound: We consider the properties of the type II Weyl semimetals at low temperatures\nbasing on the particular tight - binding model. In the presence of electric\nfield directed along the line connecting the Weyl points of opposite chirality\nthe occupied states flow along this axis giving rise to the creation of\nelectron - hole pairs. The electrons belong to a vicinity of one of the two\ntype II Weyl points while the holes belong to the vicinity of the other. This\nprocess may be considered as the manifestation of the chiral anomaly that\nexists without any external magnetic field. It may be observed experimentally\nthrough the measurement of conductivity. Next, we consider the modification of\nthe theory in the presence of elastic deformations. In the domain of the\nconsidered model, where it describes the type I Weyl semimetals the elastic\ndeformations lead to the appearance of emergent gravity. In the domain of the\ntype II Weyl semimetals the form of the Fermi surface is changed due to the\nelastic deformations, and its fluctuations represent the special modes of the\nzero sound. We find that there is one - to one correspondence between them and\nthe sound waves of the elasticity theory. Next, we discuss the influence of the\nelastic deformations on the conductivity. The particularly interesting case is\nwhen our model describes the intermediate state between the type I and the type\nII Weyl semimetal. Then without the elastic deformations there are the Fermi\nlines instead of the Fermi points/Fermi surface, while the DC conductivity\nvanishes. However, even small elastic deformations may lead to the appearance\nof large conductivity.",
        "category": "cond-mat"
    },
    {
        "text": "Ultra-low-energy computing paradigm using giant spin Hall devices: Spin Hall effect converts charge current to spin current, which can exert\nspin-torque to switch the magnetization of a nanomagnet. Recently, it is shown\nthat the ratio of spin current to charge current using spin Hall effect can be\nmade more than unity by using the areal geometry judiciously, unlike the case\nof conventional spin-transfer-torque switching of nanomagnets. This can enable\nenergy-efficient means to write a bit of information in nanomagnets. Here, we\nstudy the energy dissipation in such spin Hall devices. By solving stochastic\nLandau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of\nroom temperature thermal fluctuations, we show a methodology to simultaneously\nreduce switching delay, its variance and energy dissipation, while lateral\ndimensions of the spin Hall devices are scaled down.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetization controlled by crystallization in soft magnetic\n  Fe-Si-B-P-Cu alloys: Soft magnetic materials have low coercive fields and high permeability.\nRecently, nanocrystalline alloys obtained using annealing amorphous alloys have\nattracted much interest since nanocrystalline alloys with small grain sizes of\ntens of nanometers exhibit low coercive fields comparable to that of amorphous\nalloys. Since nanocrystalline soft magnetic materials attain remarkable soft\nmagnetic properties by controlling the grain size, the crystal grains'\nmicrostructure has a substantial influence on the soft magnetic properties. In\nthis research, we examined the magnetic properties of Fe-Si-B-P-Cu\nnanocrystalline soft magnetic alloys obtained by annealing amorphous alloys.\nDuring crystallization, the observation findings reveal the correlation between\nthe generated microstructures and soft magnetic properties.",
        "category": "cond-mat"
    },
    {
        "text": "Cluster mean-field study of the parity conserving phase transition: The phase transition of the even offspringed branching and annihilating\nrandom walk is studied by N-cluster mean-field approximations on\none-dimensional lattices. By allowing to reach zero branching rate a phase\ntransition can be seen for any N <= 12.The coherent anomaly extrapolations\napplied for the series of approximations results in $\\nu_{\\perp}=1.85(3)$ and\n$\\beta=0.96(2)$.",
        "category": "cond-mat"
    },
    {
        "text": "Non-local quantum fluctuations and fermionic superfluidity in the\n  imbalanced attractive Hubbard model: We study fermionic superfluidity in strongly anisotropic optical lattices\nwith attractive interactions utilizing the cluster DMFT method, and focusing in\nparticular on the role of non-local quantum fluctuations. We show that\nnon-local quantum fluctuations impact the BCS superfluid transition\ndramatically. Moreover, we show that exotic superfluid states with delicate\norder parameter structure, such as the Fulde-Ferrell-Larkin-Ovchinnikov phase\ndriven by spin population imbalance, can emerge even in the presence of such\nstrong fluctuations.",
        "category": "cond-mat"
    },
    {
        "text": "Analytically solvable model of an electronic Mach-Zehnder interferometer: We consider a class of models of non-equilibrium electronic Mach-Zehnder\ninterferometers built on integer quantum Hall edges states. The models are\ncharacterized by the electron-electron interaction being restricted to the\ninner part of the interferometer and transmission coefficients of the quantum\nquantum point contacts, defining the interferometer, which may take arbitrary\nvalues from zero to one. We establish an exact solution of these models in\nterms of single-particle quantities --- determinants and resolvents of Fredholm\nintegral operators. In the general situation, the results can be obtained\nnumerically. In the case of strong charging interaction, the operators acquire\nthe block Toeplitz form. Analyzing the corresponding Riemann-Hilbert problem,\nwe reduce the result to certain singular single-channel determinants (which are\na generalization of Toeplitz determinants with Fisher-Hartwig singularities),\nand obtain an analytic result for the interference current (and, in particular,\nfor the visibility of Aharonov-Bohm oscillations). Our results, which are in\ngood agreement with experimental observations, show an intimate connection\nbetween the observed \"lobe\" structure in the visibility of Aharonov-Bohm\noscillations and multiple branches in the asymptotics of singular integral\ndeterminants.",
        "category": "cond-mat"
    },
    {
        "text": "Ferroelastic twin wall mediated ferro-flexoelectricity and bulk\n  photovoltaic effect in SrTiO$_3$: Ferroelastic twin walls in nonpolar materials can give rise to a spontaneous\npolarization due to symmetry breaking. Nevertheless, the bi-stable polarity of\ntwin walls and its reversal have not yet been demonstrated. Here, we report\nthat the polarity of SrTiO$_3$ twin walls can be switched by ultra-low strain\ngradient. Using first-principles-based machine-learning potential, we\ndemonstrate that the twin walls can be deterministically rotated and realigned\nin specific directions under strain gradient, which breaks the inversion\nsymmetry of a sequence of walls and leads to a macroscopic polarization. The\nsystem can maintain polarity even after the strain gradient is removed. As a\nresult, the polarization of twin walls can exhibit ferroelectric-like\nhysteresis loop upon cyclic bending, namely ferro-flexoelectricity. Finally, we\npropose a scheme to experimentally detect the polarity of twin wall by\nmeasuring the bulk photovoltaic responses. Our findings suggest a\ntwin-wall-mediated ferro-flexoelectricity in SrTiO$_3$, which could be\npotentially exploited as functional elements in nano-electronic devices design.",
        "category": "cond-mat"
    },
    {
        "text": "Computing solubility and thermodynamics properties of H2O2 in water: Hydrogen peroxide plays a key role in many environmental and industrial\nchemical processes. We performed classical Molecular Dynamics and Continuous\nFractional Component Monte Carlo simulations to calculate thermodynamic\nproperties of H2O2 in aqueous solutions. The quality of the available force\nfields for H2O2 developed by Orabi & English, and by Cordeiro was\nsystematically evaluated. To assess which water force field is suitable for\npredicting properties of H2O2 in aqueous solutions, four water force fields\nwere used, namely the TIP3P, TIP4P/2005, TIP5P-E, and a modified TIP3P force\nfield. While the computed densities of pure H2O2 in the temperature range of\n253-353 K using the force field by Orabi & English are in excellent agreement\nwith experimental results, the densities using the force field by Cordeiro are\nunderestimated by 3%. The TIP4P/2005 force field in combination with the H2O2\nforce field developed by Orabi & English can predict the densities of H2O2\naqueous solution for the whole range of H2O2 mole fractions in very good\nagreement with experimental results. The TIP4P/2005 force field in combination\nwith either of the H2O2 force fields can predict the viscosities of H2O2\naqueous solutions for the whole range of H2O2 mole fractions in good agreement\nwith experimental results. The diffusion coefficients for H2O2 and water\nmolecules using the TIP4P/2005 force field with either of the H2O2 force fields\nare almost constant for the whole range of H2O2 mole fractions. The Cordeiro\nforce field for H2O2 in combination with either of the water force fields can\npredict the Henry coefficients of H2O2 in water in better agreement with\nexperimental values than the force field by Orabi & English.",
        "category": "cond-mat"
    },
    {
        "text": "On the mechanical modeling of the extreme softening/stiffening response\n  of axially loaded tensegrity prisms: We study the geometrically nonlinear behavior of uniformly compressed\ntensegrity prisms, through fully elastic and rigid--elastic models. The\npresented models predict a variety of mechanical behaviors in the regime of\nlarge displacements, including an extreme stiffening-type response, already\nknown in the literature, and a newly discovered, extreme softening behavior.\nThe latter may lead to a snap buckling event producing an axial collapse of the\nstructure. The switching from one mechanical regime to another depends on the\naspect ratio of the structure, the magnitude of the applied prestress, and the\nmaterial properties of the constituent elements. We discuss potential acoustic\napplications of such behaviors, which are related to the design and manufacture\nof tensegrity lattices and innovative phononic crystals.",
        "category": "cond-mat"
    },
    {
        "text": "Reduction in energy dissipation rate with increased effective applied\n  field: Dynamics of the response of type-II superconductors to a time-varying\nmagnetic field can exhibit a rate-independent or rate-dependent hysteresis. An\nenergy dissipation rate in a superconductor placed in a time-varying magnetic\nfield depends on its wave form and type of hysteresis, which depends on\ntemperature. The same wave form may reduce the energy dissipation rate in the\ncase of true hysteresis, while it may increase the energy dissipation rate in\nthe case of dynamic hysteresis compared with an energy dissipation rate in a\npure sinusoidal field. We present experimental data which confirm the energy\ndissipation rate calculated using the critical state theory for the case of\nrate-independent hysteresis and limiting behavior in a normal state for the\ncase of rate-dependent hysteresis.",
        "category": "cond-mat"
    },
    {
        "text": "BCS-BEC Crossover and Pairing Fluctuations in a Two Band\n  Superfluid/Superconductor: A T Matrix Approach: We investigate pairing fluctuation effects in a two band fermionic system,\nwhere a shallow band in the Bardeen--Cooper--Schrieffer--Bose--Einstein\ncondensation (BCS-BEC) crossover regime is coupled with a weakly interacting\ndeep band. Within a diagrammatic $T$ matrix approach, we~report how\nthermodynamic quantities such as the critical temperature, chemical potential,\n{and~momentum distributions} undergo the crossover from the BCS to BEC regime\nby tuning the intraband coupling in the shallow band. We also generalize the\ndefinition of Tan's contact to a two band system and report the two contacts\nfor different pair-exchange couplings. The present results are compared with\nthose obtained by the simpler Nozi\\`eres--Schmitt--Rink approximation. We\nconfirm a pronounced enhancement of the critical temperature due to the\nmultiband configuration, as well as to the pair-exchange coupling.",
        "category": "cond-mat"
    },
    {
        "text": "Phase diagram of geometric d-wave superconductor Josephson junctions: We show that a constriction-type Josephson junction realized by an epitactic\nthin film of a d-wave superconductor with an appropriate boundary geometry\nexhibits intrinsic phase differences between 0 and pi depending on geometric\nparameters and temperature. Based on microscopic Eilenberger theory, we provide\na general derivation of the relation between the change of the free energy of\nthe junction and the current-phase relation. From the change of the free\nenergy, we calculate phase diagrams and discuss transitions driven by geometric\nparameters and temperature.",
        "category": "cond-mat"
    },
    {
        "text": "Time-reversal symmetry breaking state in dirty three-band superconductor: I study the effects of disorder on the superconductivity of a three-band\nmodel with repulsive interband pairing. Such a model can support several\npossible superconducting order parameters, including a complex time-reversal\nsymmetry breaking (TRSB) state. Impurity scattering suppresses the critical\ntemperature of all these states, but the complex state survives, and remains a\npart of the phase diagram of the model even in the presence of moderate amount\nof disorder. This means that the TRSB states could be experimentally accessible\nin multiband materials like iron pnictides and chalcogenides.",
        "category": "cond-mat"
    },
    {
        "text": "Exact weak-coupling radius of the Holstein polaron in one, two, and\n  three dimensions: We apply weak-coupling perturbation theory to the Holstein molecular crystal\nmodel in order to compute an electron-phonon correlation function\ncharacterizing the shape and size of the polaron lattice distortion in one,\ntwo, and three dimensions. This correlation function is computed exactly to\nleading order in the electron-phonon coupling constant, permitting a complete\ndescription of correlations in any dimension for both isotropic and arbitrarily\nanisotropic cases. Using this exact result, the width of the polaron is\ncharacterized along arbitrary directions. The width of the polaron thus\ndetermined disagrees in every dimension with some well-known characterizations\nof polarons, signalling in particular the breakdown of the adiabatic\napproximation and the characterizations of self-trapping associated with it.",
        "category": "cond-mat"
    },
    {
        "text": "Evidence of exchange-striction and charge disproportionation in the\n  magneto-electric material Ni3TeO6: The chiral magneto-electric compound Ni3TeO6 is investigated through\ntemperature-dependent synchrotron-based powder x-ray diffraction and x-ray\nabsorption spectroscopy between 15 to 300 K. Our work provides direct evidence\nfor the exchange-striction in the material around the concomitant onset point\nof collinear antiferromagnetic and magneto-electric phases. The x-ray\nabsorption near edge spectra and x-ray photoelectron spectra show that the\nsample consists of both Ni2+ and Ni3+ ions in the lattice. The ionic state of\nNi is found to be quite robust, and it is largely independent of the\npreparation route. Additionally, the minority Te4+ state is found to coexist\nwith the majority Te6+ state, which may arise from the charge\ndisproportionation between Ni and Te ions (Ni2+ + Te6+ --> Ni3+ + Te4+). The\nobserved mixed valency of Ni is also confirmed by the total paramagnetic moment\nper Ni atom in the system. This mixed valency in the metal ions and the\nexchange-striction may be attributed to the observed magneto-electric effect in\nthe system.",
        "category": "cond-mat"
    },
    {
        "text": "SiNx:Tb3+--Yb3+, an efficient down-conversion layer compatible with a\n  silicon solar cell process: SiN x : Tb 3+-Yb 3+, an efficient down-conversion layer compatible with\nsilicon solar cell process Abstract Tb 3+-Yb 3+ co-doped SiN x down-conversion\nlayers compatible with silicon Photovoltaic Technology were prepared by\nreactive magnetron co-sputtering. Efficient sensitization of Tb 3+ ions through\na SiN x host matrix and cooperative energy transfer between Tb 3+ and Yb 3+\nions were evidenced as driving mechanisms of the down-conversion process. In\nthis paper, the film composition and microstructure are investigated alongside\ntheir optical properties, with the aim of maximizing the rare earth ions\nincorporation and emission efficiency. An optimized layer achieving the highest\nYb 3+ emission intensity was obtained by reactive magnetron co-sputtering in a\nnitride rich atmosphere for 1.2 W/cm${}^2$ and 0.15 W/cm${}^2$ power density\napplied on the Tb and Yb targets, respectively. It was determined that\ndepositing at 200 {\\textdegree}C and annealing at 850 {\\textdegree}C leads to\ncomparable Yb 3+ emission intensity than depositing at 500 {\\textdegree}C and\nannealing at 600 {\\textdegree}C, which is promising for applications toward\nsilicon solar cells.",
        "category": "cond-mat"
    },
    {
        "text": "Generation of optical potentials for ultracold atoms using a\n  superluminescent diode: We report on the realization and characterisation of optical potentials for\nultracold atoms using a superluminescent diode. The light emitted by this class\nof diodes is characterised by high spatial coherence but low temporal\ncoherence. On the one hand, this implies that it follows Gaussian propagation\nsimilar to lasers, allowing for high intensities and well-collimated beams. On\nthe other, it significantly reduces those interference effects that lead to\nsevere distortions in imaging. By using a high-resolution optical setup, we\nproduce patterned optical potentials with a digital micromirror device and\ndemonstrate that the quality of the patterns produced by our superluminescent\ndiode is consistently and substantially higher than those produced by our\nlaser. We show that the resulting optical potentials can be used to arrange the\natoms in arbitrary structures and manipulate them dynamically. Our results can\nopen new opportunities in the fields of quantum simulations and atomtronics.",
        "category": "cond-mat"
    },
    {
        "text": "Structure and diffusion time scales of disordered clusters: The eigenvalue spectra of the transition probability matrix for random walks\ntraversing critically disordered clusters in three different types of\npercolation problems show that the random walker sees a developing Euclidean\nsignature for short time scales as the local, full-coordination constraint is\niteratively applied.",
        "category": "cond-mat"
    },
    {
        "text": "Resonance Plasmon Linewidth Oscillations in Spheroidal Metallic\n  Nanoparticle Embedded in a Dielectric Matrix: The kinetic approach is applied to calculate oscillations of a surface\nplasmon linewidth in a spheroidal metal nanoparticle embedded in any dielectric\nmedia. The principal attention is focused on the case, when the free electron\npath is much greater than the particle size.\n  The linewidth of the plasmon resonance as a function of the particle radius,\nshape, dielectric constant of the surrounding medium, and the light frequency\nis studied in detail. It is found that the resonance plasmon linewidth\noscillates with increasing both the particle size and the dielectric constant\nof surrounding medium.\n  The main attention is paid to the electron surface-scattering contribution to\nthe plasmon decay.\n  All calculations the plasmon resonance linewidth are illustrated by the\nexample of the Na nanoparticles with different radii.\n  The results obtained in the kinetic approach are compared with the known ones\nfrom other models.\n  The role of the radiative damping is discussed as well.",
        "category": "cond-mat"
    },
    {
        "text": "Emergence of one-dimensional wires of free carriers in\n  transition-metal-dichalcogenide nanostructures: We highlight the emergence of metallic states in two-dimensional\ntransition-metal-dichalcogenide nanostructures -nanoribbons, islands, and\ninversion domain boundaries- as a widespread and universal phenomenon driven by\nthe polar discontinuities occurring at their edges or boundaries. We show that\nsuch metallic states form one-dimensional wires of electrons or holes, with a\nfree charge density that increases with the system size, up to complete\nscreening of the polarization charge, and can also be controlled by the\nspecific edge or boundary configurations, e.g. through chemisorption of\nhydrogen or sulfur atoms at the edges. For triangular islands, local polar\ndiscontinuities occur even in the absence of a total dipole moment for the\nisland and lead to an accumulation of free carriers close to the edges,\nproviding a consistent explanation of previous experimental observations. To\nfurther stress the universal character of these mechanisms, we show that polar\ndiscontinuities give rise to metallic states also at inversion domain\nboundaries. These findings underscore the potential of engineering\ntransition-metal-dichalcogenide nanostructures for manifold applications in\nnano- and opto-electronics, spintronics, catalysis, and solar-energy\nharvesting.",
        "category": "cond-mat"
    },
    {
        "text": "Spectral partitions on infinite graphs: Statistical models on infinite graphs may exhibit inhomogeneous thermodynamic\nbehaviour at macroscopic scales. This phenomenon is of geometrical origin and\nmay be properly described in terms of spectral partitions into subgraphs with\nwell defined spectral dimensions and spectral weights. These subgraphs are\nshown to be thermodynamically homogeneous and effectively decoupled.",
        "category": "cond-mat"
    },
    {
        "text": "Double-$Q$ spin chirality stripes in the anomalous Hall antiferromagnet\n  CoNb$_3$S$_6$: The metallic antiferromagnet CoNb$_3$S$_6$ exhibits a giant anomalous Hall\neffect (AHE) that cannot be explained by a collinear N\\'eel order on\nintercalated Co ions. Thus, a noncoplanar structure is expected. We carried out\nresonant elastic x-ray scattering (REXS) to reexamine the magnetic structure of\nCoNb$_3$S$_6$ and found a double-$Q$ ($2Q$) order with a $(\\frac{1}{2}00)$\ncommensurate component and a long-wavelength modulation. Circular dichroism and\nlinear polarization analysis reveal that the commensurate components on the two\nCo sites are noncollinear and the modulation is helical. The resulting magnetic\nstructure has a staggered scalar spin chirality forming a stripe pattern in\nreal space. Furthermore, we found that the helical modulation wavevector\nexhibits a sample dependence and develops a low-symmetry domain structure. We\npropose that quenched-in lattice strain controls the helical domain structure,\naccounting for much of the sample dependence. These results provide insight\ninto the mechanism of the AHE in CoNb$_3$S$_6$ and identifies potential routes\nfor controlling the Hall response and realizing other unconventional electronic\nphenomena in metallic antiferromagnets.",
        "category": "cond-mat"
    },
    {
        "text": "Imaging the itinerant-to-localized transmutation of electrons across the\n  metal-to-insulator transition in V$_2$O$_3$: In solids, strong repulsion between electrons can inhibit their movement and\nresult in a \"Mott\" metal-to-insulator transition (MIT), a fundamental\nphenomenon whose understanding has remained a challenge for over 50 years. A\nkey issue is how the wave-like itinerant electrons change into a localized-like\nstate due to increased interactions. However, observing the MIT in terms of the\nenergy- and momentum-resolved electronic structure of the system, the only\ndirect way to probe both itinerant and localized states, has been elusive. Here\nwe show, using angle-resolved photoemission spectroscopy (ARPES), that in\nV$_2$O$_3$ the temperature-induced MIT is characterized by the progressive\ndisappearance of its itinerant conduction band, without any change in its\nenergy-momentum dispersion, and the simultaneous shift to larger binding\nenergies of a quasi-localized state initially located near the Fermi level.",
        "category": "cond-mat"
    },
    {
        "text": "Hybrid surface waves in two-dimensional Rashba-Dresselhaus materials: We address the electromagnetic properties of two-dimensional electron gas\nconfined by a dielectric environment in the presence of both Rashba and\nDresselhaus spin-orbit interactions. It is demonstrated that off-diagonal\ncomponents of the conductivity tensor resulting from a delicate interplay\nbetween Rashba and Dresselhaus couplings lead to the hybridization of\ntransverse electric and transverse magnetic surface electromagnetic modes\nlocalized at the interface. We show that the characteristics of these hybrid\nsurface waves can be controlled by additional intense external off-resonant\ncoherent pumping.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of external electric field on the charge density waves in one\n  dimensional Hubbard superlattices: We have studied the ground state of the one dimensional Hubbard superlattice\nstructures with different unit cell sizes in the presence of electric field.\nSelf consistent Hartree-Fock approximation calculation is done in the weak to\nintermediate interaction regime. Studying the charge gap at the Fermi level and\nthe charge density structure factor, we get an idea how the charge modulation\non the superlattice is governed by the competition between the electronic\ncorrelation and the external electric field.",
        "category": "cond-mat"
    },
    {
        "text": "AC Conductance in Dense Array of the Ge$_{0.7}$Si$_{0.3}$ Quantum Dots\n  in Si: Complex AC-conductance, $\\sigma^{AC}$, in the systems with dense\nGe$_{0.7}$Si$_{0.3}$ quantum dot (QD) arrays in Si has been determined from\nsimultaneous measurements of attenuation, $\\Delta\\Gamma=\\Gamma(H)-\\Gamma(0)$,\nand velocity, $\\Delta V /V=(V(H)-V(0)) / V(0)$, of surface acoustic waves (SAW)\nwith frequencies $f$ = 30-300 MHz as functions of transverse magnetic field $H\n\\leq$ 18 T in the temperature range $T$ = 1-20 K. It has been shown that in the\nsample with dopant (B) concentration 8.2$ \\times 10^{11}$ cm$^{-2}$ at\ntemperatures $T \\leq$4 K the AC conductivity is dominated by hopping between\nstates localized in different QDs. The observed power-law temperature\ndependence, $\\sigma_1(H=0)\\propto T^{2.4}$, and weak frequency dependence,\n$\\sigma_1(H=0)\\propto \\omega^0$, of the AC conductivity are consistent with\npredictions of the two-site model for AC hopping conductivity for the case of\n$\\omega \\tau_0 \\gg $1, where $\\omega=2\\pi f$ is the SAW angular frequency and\n$\\tau_0$ is the typical population relaxation time. At $T >$ 7 K the AC\nconductivity is due to thermal activation of the carriers (holes) to the\nmobility edge. In intermediate temperature region 4$ < T<$ 7 K, where AC\nconductivity is due to a combination of hops between QDs and diffusion on the\nmobility edge, one succeeded to separate both contributions. Temperature\ndependence of hopping contribution to the conductivity above $T^*\\sim$ 4.5 K\nsaturates, evidencing crossover to the regime where $\\omega \\tau_0 < $1. From\ncrossover condition, $\\omega \\tau_0(T^*)$ = 1, the typical value, $\\tau_0$, of\nthe relaxation time has been determined.",
        "category": "cond-mat"
    },
    {
        "text": "Critical Phenomena of Ferromagnetic Transition in Double-Exchange\n  Systems: Critical phenomena of ferromagnetic transition at finite temperatures are\nstudied in double-exchange systems. In order to investigate strong interplay\nbetween charge and spin degrees of freedom, Monte Carlo technique is applied to\ninclude fluctuations in a controlled and unbiased manner. By using finite-size\nscaling analysis, critical exponents and transition temperature are estimated\nfor a model with Ising spin symmetry in two dimensions. The obtained exponents\nare far distinct from the mean-field values, but consistent with those of spin\nmodels with short-range exchange interactions. The universality class of this\ntransition belongs to that of short-range interaction with the same spin\nsymmetry. We also discuss the case for three dimensions. The results are\ncompared with experimental results in perovskite manganites which show colossal\nmagnetoresistance.",
        "category": "cond-mat"
    },
    {
        "text": "From many-body oscillations to thermalization in an isolated spinor gas: The dynamics of a many-body system can take many forms, from a purely\nreversible evolution to fast thermalization. Here we show experimentally and\nnumerically that an assembly of spin 1 atoms all in the same spatial mode\nallows one to explore this wide variety of behaviors. When the system can be\ndescribed by a Bogoliubov analysis, the relevant energy spectrum is linear and\nleads to undamped oscillations of many-body observables. Outside this regime,\nthe non-linearity of the spectrum leads to irreversibity, characterized by a\nuniversal behavior. When the integrability of the Hamiltonian is broken, a\nchaotic dynamics emerges and leads to thermalization, in agreement with the\nEigenstate Thermalization Hypothesis paradigm.",
        "category": "cond-mat"
    },
    {
        "text": "Mechanism of Polarization Fatigue in BiFeO3: the Role of Schottky\n  Barrier: By using piezoelectric force microscopy and scanning Kelvin probe microscopy,\nwe have investigated the domain evolution and space charge distribution in\nplanar BiFeO3 capacitors with different electrodes. It is observed that charge\ninjection at the film/electrode interface leads to domain pinning and\npolarization fatigue in BiFeO3. Furthermore, the Schottky barrier at the\ninterface is crucial for the charge injection process. Lowering the Schottky\nbarrier by using low work function metals as the electrodes can also improve\nthe fatigue property of the device, similar to what oxide electrodes can\nachieve.",
        "category": "cond-mat"
    },
    {
        "text": "Interface effects on titanium growth on graphene: Poor quality interfaces between metal and graphene cause non-linearity and\nimpair the carrier mobility in graphene devices. Here, we use aberration\ncorrected scanning transmission electron microscopy to observe hexagonally\nclose-packed Ti nano-islands grown on atomically clean graphene, and establish\na 30{\\deg} epitaxial relationship between the lattices. Due to the strong\nbinding of Ti on graphene, at the limit of a monolayer, the Ti lattice constant\nis mediated by the graphene epitaxy, and compared to bulk Ti, is strained by\nca. 3.7% to a value of 0.306(3) nm. The resulting interfacial strain is\nslightly greater than what has been predicted by density functional theory\ncalculations. Our early growth stage investigations also reveal that, in\ncontrast to widespread assumptions, Ti does not fully wet graphene but grows\ninitially in clusters with a thickness of 1-2 layers. Raman spectroscopy\nimplies charge transfer between the Ti islands and graphene substrate.",
        "category": "cond-mat"
    },
    {
        "text": "Structure and energetics of carbon-related defects in SiC\n  (0001)/SiO$_{\\rm 2}$ systems revealed by first-principles calculations:\n  Defects in SiC, SiO$_{\\rm 2}$, and just at their interface: We report first-principles calculations that reveal the atomic forms,\nstability, and energy levels of carbon-related defects in SiC (0001)/SiO$_{\\rm\n2}$ systems. We clarify the stable position (SiC side, SiO$_{\\rm 2}$ side, or\njust at the SiC/SiO$_{\\rm 2}$ interface) of defects depending on the oxidation\nenvironment. Under an O-rich condition, the di-carbon antisite ((C$_{\\rm\n2}$)$_{\\rm Si}$) in the SiC side is stable and critical for $n$-channel\nMOSFETs, whereas the di-carbon defect (Si-C-C-Si) at the interface becomes\ncritical under an O-poor condition. Our results suggest that the oxidation of\nSiC under a high-temperature O-poor condition is favorable in reducing the\ndefects, in consistent with recent experimental reports.",
        "category": "cond-mat"
    },
    {
        "text": "Elucidating the initial steps in \u03b1-uranium hydriding using\n  first-principles calculations: Hydrogen embrittlement of uranium, which arises due to the formation of a\nstructurally weak pyrophoric hydride, poses a major safety risk in material\napplications. Previous experiments have shown that hydriding begins on top or\nnear the surface (i.e., subsurface) of a-uranium. However, the fundamental\nmolecular-level mechanism of this process remains unknown. In this work,\nstarting from pristine {\\alpha}-U bulk and surfaces, we present a systematic\ninvestigation of possible mechanisms for formation of the metal hydride.\nSpecifically, we address this problem by examining the individual steps of\nhydrogen embrittlement, including surface adsorption, subsurface absorption,\nand the inter-layer diffusion of atomic hydrogen. Furthermore, by examining\nthese processes across different facets, we highlight the importance of both\n(1) hydrogen monolayer coverage and (2) applied tensile strain on hydriding\nkinetics. Taken together, by studying previously overlooked phenomena, this\nstudy provides foundational insights into the initial steps of this overall\ncomplex process. We anticipate that this work will guide near-term future\ndevelopment of multiscale kinetic models for uranium hydriding and\nsubsequently, identify potential strategies to mitigate this undesired process.",
        "category": "cond-mat"
    },
    {
        "text": "Spin mixing between subbands and extraordinary Landau levels shift in\n  wide HgTe quantum wells: We present both the experimental and theoretical investigation of a\nnon-trivial electron Landau levels shift in magnetic field in wide ~20 nm HgTe\nquantum wells: Landau levels split under magnetic fields but become degenerate\nagain when magnetic field increases. We reproduced this behavior qualitatively\nwithin an isotropic 6-band Kane model, then using semiclassical calculations we\nshowed this behavior is due to the mixing of the conduction band with total\nspin 3/2 with the next well subband with spin 1/2 which reduces the average\nvertical spin from 3/2 to around 1. This change of the average spin changes the\nBerry phase explaining the evolution of Landau levels under magnetic field.",
        "category": "cond-mat"
    },
    {
        "text": "Machine Learning Percolation Model: Recent advances in machine learning have become increasingly popular in the\napplications of phase transitions and critical phenomena. By machine learning\napproaches, we try to identify the physical characteristics in the\ntwo-dimensional percolation model. To achieve this, we adopt Monte Carlo\nsimulation to generate dataset at first, and then we employ several approaches\nto analyze the dataset. Four kinds of convolutional neural networks (CNNs), one\nvariational autoencoder (VAE), one convolutional VAE (cVAE), one principal\ncomponent analysis (PCA), and one $k$-means are used for identifying order\nparameter, the permeability, and the critical transition point. The former\nthree kinds of CNNs can simulate the two order parameters and the permeability\nwith high accuracy, and good extrapolating performance. The former two kinds of\nCNNs have high anti-noise ability. To validate the robustness of the former\nthree kinds of CNNs, we also use the VAE and the cVAE to generate new\npercolating configurations to add perturbations into the raw configurations. We\nfind that there is no difference by using the raw or the perturbed\nconfigurations to identify the physical characteristics, under the prerequisite\nof corresponding labels. In the case of lacking labels, we use unsupervised\nlearning to detect the physical characteristics. The PCA, a classical\nunsupervised learning, performs well when identifying the permeability but\nfails to deduce order parameter. Hence, we apply the fourth kinds of CNNs with\ndifferent preset thresholds, and identify a new order parameter and the\ncritical transition point. Our findings indicate that the effectiveness of\nmachine learning still needs to be evaluated in the applications of phase\ntransitions and critical phenomena.",
        "category": "cond-mat"
    },
    {
        "text": "Unusual eigenvalue spectrum and relaxation in the L\u00e9vy\n  Ornstein-Uhlenbeck process: We consider the rates of relaxation of a particle in a harmonic well, subject\nto L\\'evy noise characterized by its L\\'evy index $\\mu$. Using the propagator\nfor this L\\'evy Ornstein-Uhlenbeck process (LOUP), we show that the eigenvalue\nspectrum of the associated Fokker-Planck operator has the form $(n+m\\mu)\\nu$\nwhere $\\nu$ is the force constant characterizing the well, and\n$n,m\\in\\mathbb{N}$. If $\\mu$ is irrational, the eigenvalues are all\nnon-degenerate, but rational $\\mu$ can lead to degeneracy. The maximum\ndegeneracy is shown to be two. The left eigenfunctions of the fractional\nFokker-Planck operator are very simple while the right eigenfunctions may be\nobtained from the lowest eigenfunction by a combination of two different\nstep-up operators. Further, we find that the acceptable eigenfunctions should\nhave the asymptotic behavior $|x|^{-n_1+n_2\\;\\mu}$ as $|x| \\rightarrow \\infty$,\nwith $n_1$ and $n_2$ being positive integers, though this condition alone is\nnot enough to identify them uniquely. We also assert that the rates of\nrelaxation of LOUP are determined by the eigenvalues of the associated\nfractional Fokker-Planck operator and do not depend on the initial state if the\nmoments of the initial distribution are all finite. If the initial distribution\nhas fat tails, for which the higher moments diverge, one would have\nnon-spectral relaxation, as pointed out by Toenjes et. al (Physical Review\nLetters, 110, 150602 (2013)).",
        "category": "cond-mat"
    },
    {
        "text": "A droplet near the critical point: the divergence of Tolman's length: Application of \"complete scaling\" [Kim et al., Phys. Rev. E 67, 061506\n(2003); Anisimov and Wang, Phys. Rev. Lett. 97, 25703 (2006)] to the\ninterfacial behavior of fluids shows that Tolman's length, a curvature\ncorrection to the surface tension, diverges at the critical point of fluids\nmuch more strongly than is commonly believed. The amplitude of the divergence\ndepends on the degree of asymmetry in fluid phase coexistence. A new universal\namplitude ratio, which involves this asymmetry, is introduced. In highly\nasymmetric fluids and fluid mixtures the Tolman length may become large enough\nnear criticality to be detected in precise experiments with microcapillaries\nand in simulations.",
        "category": "cond-mat"
    },
    {
        "text": "The dynamics of azurite Cu$_3$(CO$_3$)$_2$(OH)$_2$ in a magnetic field\n  as determined by neutron scattering: Azurite, a natural mineral made up of CuO chains, is also an intriguing\nspin-1/2 quantum magnet. There has been much debate as to the 1-dimensional\n(1D) nature of this material by theorists and experimentalists alike. The focus\nof this debate lies in the interactions between Cu-ions within the\nantiferromagnetically ordered state below 1.9 K. We present high-resolution\ninelastic neutron scattering data which highlight the complexity of the\nmagnetic ground state of azurite. The application of magnetic fields and\ntemperatures were used to probe the excitations revealing important information\nabout the dynamics in this system. From this we are able to conclude that the\n1D Heisenberg antiferromagnetic spin chain model is not sufficient to describe\nthe dynamics in azurite. Instead additional coupling including interchain\ninteractions and an anisotropic staggered field are necessary to fully model\nthe observed excitations.",
        "category": "cond-mat"
    },
    {
        "text": "Zero temperature dynamics of Ising model on a densely connected small\n  world network: The zero temperature quenching dynamics of the ferromagnetic Ising model on a\ndensely connected small world network is studied where long range bonds are\nadded randomly with a finite probability $p$. We find that in contrast to the\nsparsely connected networks and random graph, there is no freezing and an\ninitial random configuration of the spins reaches the equilibrium configuration\nwithin a very few Monte Carlo time steps in the thermodynamic limit for any $p\n\\ne 0$. The residual energy and the number of spins flipped at any time shows\nan exponential relaxation to equilibrium. The persistence probability is also\nstudied and it shows a saturation within a few time steps, the saturation value\nbeing 0.5 in the thermodynamic limit. These results are explained in the light\nof the topological properties of the network which is highly clustered and has\na novel small world behaviour.",
        "category": "cond-mat"
    },
    {
        "text": "Energy landscapes in random systems, driven interfaces and wetting: We discuss the zero-temperature susceptibility of elastic manifolds with\nquenched randomness. It diverges with system size due to low-lying local\nminima. The distribution of energy gaps is deduced to be constant in the limit\nof vanishing gaps by comparing numerics with a probabilistic argument. The\ntypical manifold response arises from a level-crossing phenomenon and implies\nthat wetting in random systems begins with a discrete transition. The\nassociated ``jump field'' scales as $<h > \\sim L^{-5/3}$ and $L^{-2.2}$ for\n(1+1) and (2+1) dimensional manifolds with random bond disorder.",
        "category": "cond-mat"
    },
    {
        "text": "The 5D term origin of the excited triplet in LaCoO3: We provide the proof for the 5D term origin of an excited triplet observed in\nthe recent electron-spin-resonance (ESR) experiments by Noguchi et al. (Phys.\nRev. B 66, 094404 (2002)). We have succeeded to fully describe experimental ESR\nresults both for the zero-field g-factor, of 3.35, and the splitting D of 4.90\ncm-1, as well as for the magnetic field applied along different\ncrystallographic directions within the localized electron atomic-like approach\nas originating from excitations within the lowest triplet of the 5T2g\noctahedral subterm of the 5D term. In our atomic-like approach the d electrons\nof the Co3+ ion in LaCoO3 form the highly-correlated atomic-like 3d6 system\nwith the singlet 1A1 ground state (an octahedral subterm of the 1I term) and\nthe excited octahedral subterm 5T2g of the 5D term. We take the ESR experiment\nas confirmation of the existence of the discrete electronic structure for 3d\nelectron states in LaCoO3 in the meV scale.\n  PACS No: 76.30.Fc; 75.10.Dg : 73.30.-m\n  Keywords: electronic structure, crystal field, spin-orbit coupling, LaCoO3\nSubmitted 24.12.2002 to Phys. Rev. B.",
        "category": "cond-mat"
    },
    {
        "text": "Symmetrized Liouvillian Gap in Markovian Open Quantum Systems: Markovian open quantum systems display complicated relaxation dynamics. The\nspectral gap of the Liouvillian characterizes the asymptotic decay rate towards\nthe steady state, but it does not necessarily give a correct estimate of the\nrelaxation time because the crossover time to the asymptotic regime may be too\nlong. We here give a rigorous upper bound on the transient decay of\nauto-correlation functions in the steady state by introducing the symmetrized\nLiouvillian gap. The standard Liouvillian gap and the symmetrized one are\nidentical in an equilibrium situation but differ from each other in the absence\nof the detailed balance condition. It is numerically shown that the symmetrized\nLiouvillian gap always give a correct upper bound on the decay of the\nauto-correlation function, but the standard Liouvillian gap does not.",
        "category": "cond-mat"
    },
    {
        "text": "Weakly parametrized Jastrow ansatz for a strongly correlated Bose system: We consider the Jastrow pair-product wavefunction for the strongly correlated\nBose systems, in our case liquid helium-4. An ansatz is proposed for the pair\nfactors which consists of a numeric solution to a modified and parametrized\npair scattering equation. We consider a number of such simple one-variable\nparametrizations. Additionally, we allow for a parametrizeable cutoff of the\npair factors and for the addition of a long-range phonon tail. This approach\nresults in the many-body wavefunctions that have between just one and three\nparameters. Calculation of observables is carried with the Variational Monte\nCarlo method. We find that such a simple parametrization is sufficient to\nproduce results that are comparable in quality to the best available two-body\nJastrow factors for helium. For two-parameter wavefunction, we find variational\nenergies of $-6.04$~K per particle for a system of one thousand particles. It\nis also shown that short-range two-body correlations are reproduced in detail\nby two- and three-parameter functions.",
        "category": "cond-mat"
    },
    {
        "text": "Underpotential deposition of Cu on Au(111) in sulfate-containing\n  electrolytes: a theoretical and experimental study: We study the underpotential deposition of Cu on single-crystal Au(111)\nelectrodes in sulfate-containing electrolytes by a combination of computational\nstatistical-mechanics based lattice-gas modeling and experiments. The\nexperimental methods are in situ cyclic voltammetry and coulometry and ex situ\nAuger electron spectroscopy and low-energy electron diffraction. The\nexperimentally obtained voltammetric current and charge densities and adsorbate\ncoverages are compared with the predictions of a two-component lattice-gas\nmodel for the coadsorption of Cu and sulfate. This model includes effective,\nlateral interactions out to fourth-nearest neighbors. Using group-theoretical\nground-state calculations and Monte Carlo simulations, we estimate effective\nelectrovalences and lateral adsorbate--adsorbate interactions so as to obtain\noverall agreement with experiments, including both our own and those of other\ngroups. In agreement with earlier work, we find a mixed R3xR3 phase consisting\nof 2/3 monolayer Cu and 1/3 monolayer sulfate at intermediate electrode\npotentials, delimited by phase transitions at both higher and lower potentials.\nOur approach provides estimates of the effective electrovalences and lateral\ninteraction energies, which cannot yet be calculated by first-principles\nmethods.",
        "category": "cond-mat"
    },
    {
        "text": "High pressure x-ray study of spin-Peierls physics in the quantum spin\n  chain material TiOCl: The application of pressure can induce transitions between unconventional\nquantum phases in correlated materials. The inorganic compound TiOCl, composed\nof chains of S=1/2 Ti ions, is an ideal realization of a spin-Peierls system\nwith a relatively simple unit cell. At ambient pressure, it is an insulator due\nto strong electronic interactions (a Mott insulator). Its resistivity shows a\nsudden decrease with increasing pressure, indicating a transition to a more\nmetallic state which may coincide with the emergence of charge density wave\norder. Therefore, high pressure studies of the structure with x-rays are\ncrucial in determining the ground-state physics in this quantum magnet. In\nambient pressure, TiOCl exhibits a transition to an incommensurate nearly\ndimerized state at $T_{c2}=92$ K and to a commensurate dimerized state at\n$T_{c1}=66$ K. Here, we discover a rich phase diagram as a function of\ntemperature and pressure using x-ray diffraction on a single crystal in a\ndiamond anvil cell down to $T=4$ K and pressures up to 14.5 GPa. Remarkably,\nthe magnetic interaction scale increases dramatically with increasing pressure,\nas indicated by the high onset temperature of the spin-Peierls phase. At\n$\\sim$7 GPa, the extrapolated onset of the spin-Peierls phase occurs above\n$T=300$ K, indicating a quantum singlet state exists at room temperature.\nFurther comparisons are made with the phase diagrams of related spin-Peierls\nsystems that display metallicity and superconductivity under pressure.",
        "category": "cond-mat"
    },
    {
        "text": "Conversion of multilayer graphene into continuous ultrathin sp3-bonded\n  carbon films on metal surfaces: The conversion of multilayer graphenes into sp^3-bonded carbon films on metal\nsurfaces (through hydrogenation or fluorination of the outer surface of the top\ngraphene layer) is indicated through first-principles computations. The main\ndriving force for this conversion is the hybridization between carbon sp^3\norbitals and metal surface dz^2 orbitals. The induced electronic gap states in\nthe carbon layers are confined in a region within 0.5 nm of the metal surface.\nWhether the conversion occurs depend on the fraction of hydrogenated\n(fluorinated) C atoms and on the number of stacked graphene layers. In the\nanalysis of the Eliashberg spectral functions for the sp^3 carbon films on\ndiamagnetic metals, the strong covalent metal-sp^3 carbon bonds induce soft\nphonon modes that predominantly contribute to large electron-phonon couplings,\nsuggesting the possibility of phonon-mediated superconductivity. Our results\nsuggest a route to experimental realization of large-area ultrathin sp^3-bonded\ncarbon films on metal surfaces.",
        "category": "cond-mat"
    },
    {
        "text": "Persistent local order heterogeneity in the supercritical carbon dioxide: The supercritical state is currently viewed as uniform and homogeneous on the\npressure-temperature phase diagram in terms of physical properties. Here, we\nstudy structural properties of the supercritical carbon dioxide, and discover\nthe existence of persistent medium-range order correlations which make\nsupercritical carbon dioxide non-uniform and heterogeneous on an intermediate\nlength scale, a result not hitherto anticipated. We report on the carbon\ndioxide heterogeneity shell structure where, in the first shell, both carbon\nand oxygen atoms experience gas-like type inter- actions with short range order\ncorrelations, while within the second shell oxygen atoms essentially exhibit\nliquid-like type of interactions with medium range order correlations due to\nlocalisation of transverse-like phonon packets. We show that the local order\nheterogeneity remains in the three phase-like equilibrium within very wide\ntemperature range. Importantly, we highlight a catalytic role of atoms inside\nthe nearest neighbor heterogeneity shell in providing a mechanism for diffusion\nin the supercritical carbon dioxide on an intermediate length scale. Finally,\nwe discuss important implications for answering the intriguing question whether\nVenus may have had carbon dioxide oceans and urge for an experimental detection\nof this persistent local order heterogeneity.",
        "category": "cond-mat"
    },
    {
        "text": "Spin texture induced by non-magnetic doping and spin dynamics in 2D\n  triangular lattice antiferromagnet h-Y(Mn,Al)O3: Novel effects induced by nonmagnetic impurities in frustrated magnets and\nquantum spin liquid represent a highly nontrivial and interesting problem. A\ntheoretical proposal of extended modulated spin structures induced by doping of\nsuch magnets, distinct from the well-known skyrmions has attracted significant\ninterest. Here, we demonstrate that nonmagnetic impurities can produce such\nextended spin structures in h-YMnO3, a triangular antiferromagnet with\nnoncollinear magnetic order. Using inelastic neutron scattering (INS), we\nmeasured the full dynamical structure factor in Al-doped h-YMnO3 and confirmed\nthe presence of magnon damping with a clear momentum dependence. Our\ntheoretical calculations can reproduce the key features of the INS data,\nsupporting the formation of the proposed spin textures. As such, our study\nprovides the first experimental confirmation of the impurity-induced spin\ntextures. It offers new insights and understanding of the impurity effects in a\nbroad class of noncollinear magnetic systems.",
        "category": "cond-mat"
    },
    {
        "text": "Atomic structure analysis of nanocrystalline Boehmite AlO(OH): Nanocrystalline n-AlO(OH) (Disperal P2(R) of Sasol) was investigated by means\nof the atomic pair distribution function (PDF). The PDF is derived from powder\ndiffraction data, an ideally resolved PDF is obtained from a synchrotron source\nwhich provides a large maximal scattering vector length Qmax > 300 nm-1. Here,\nhowever, we were able to reveal atomic structure details of the about 4 nm\nparticles from in-house diffraction data (Qmax = 130 nm-1): PDF least squares\nmodel refinements show that n-AlO(OH) is of the layered Boehmite structure type\n(oC16, Cmcm). But the structure is uniformly distorted in domains of ca. 2 nm\nsize within the nano particles. The hydrogen bonds between the layers are\nwidened up significantly by +13 pm, accounting for the higher reactivity when\ncompared to microcrystalline Boehmite. Our results from only one\n\"nanocrystallographic\" experiment are consistent with a trend which was found\nvia the Rietveld technique on a series of AlO(OH) of different crystallite size\n(Bokhimi et al., 2001). In addition, the PDF contains information on structural\ndistortion as a function of (coherence) domain size within the nano particles.",
        "category": "cond-mat"
    },
    {
        "text": "Preferential out-of-plane conduction and quasi-one-dimensional\n  electronic states in layered 1T-TaS2: Layered transition metal dichalcogenides (TMDs) are commonly classified as\nquasi-two-dimensional materials, meaning that their electronic structure\nclosely resembles that of an individual layer, which results in resistivity\nanisotropies reaching thousands. Here, we show that this rule does not hold for\n1T-TaS2 - a compound with the richest phase diagram among TMDs. While the onset\nof charge density wave order makes the in-plane conduction non-metallic, we\nreveal that the out-of-plane charge transport is metallic and the resistivity\nanisotropy is close to one. We support our findings with ab-initio calculations\npredicting a pronounced quasi-one-dimensional character of the electronic\nstructure. Consequently, we interpret the highly debated metal-insulator\ntransition in 1T-TaS2 as a quasi-one-dimensional instability, contrary to the\nlong-standing Mott localisation picture. In a broader context, these findings\nare relevant for the newly born field of van der Waals heterostructures, where\ntuning interlayer interactions (e.g. by twist, strain, intercalation, etc.)\nleads to new emergent phenomena.",
        "category": "cond-mat"
    },
    {
        "text": "Bistable Spin Currents from Quantum Dots Embedded in a Microcavity: We examine the spin current generated by quantum dots embedded in an optical\nmicrocavity. The dots are connected to leads, which allow electrons to tunnel\ninto and out of the dot. The spin current is generated by spin flip transitions\ninduced by a quantized electromagnetic field inside the cavity with one of the\nZeeman states lying below the Fermi level of the leads and the other above. In\nthe limit of strong Coulomb blockade, this model is analogous to the\nJaynes-Cummings model in quantum optics. We find that the cavity field\namplitude and the spin current exhibit bistability as a function of the laser\namplitude, which is driving the cavity mode. Even in the limit of a single dot,\nthe spin current and the Q distribution of the cavity field have a bimodal\nstructure.",
        "category": "cond-mat"
    },
    {
        "text": "Exact Thermodynamics and Transport in the Classical Sine-Gordon Model: We revisit the exact thermodynamic description of the classical sine-Gordon\nfield theory, a notorious integrable model. We found that existing results in\nthe literature based on the soliton-gas picture did not correctly take into\naccount light, but extended, solitons and thus led to incorrect results. This\nissue is regularized upon requantization: we derive the correct thermodynamics\nby taking the semiclassical limit of the quantum model. Our results are then\nextended to transport settings by means of Generalized Hydrodynamics.",
        "category": "cond-mat"
    },
    {
        "text": "3-Wave Mixing Josephson Dipole Element: Parametric conversion and amplification based on three-wave mixing are\npowerful primitives for efficient quantum operations. For superconducting\nqubits, such operations can be realized with a quadrupole Josephson junction\nelement, the Josephson Ring Modulator (JRM), which behaves as a loss-less\nthree-wave mixer. However, combining multiple quadrupole elements is a\ndifficult task so it would be advantageous to have a pure three-wave dipole\nelement that could be tessellated for increased power handling and/or\ninformation throughput. Here, we present a dipole circuit element with\nthird-order nonlinearity, which implements three-wave mixing. Experimental\nresults for a non-degenerate amplifier based on the proposed pure third-order\nnonlinearity are reported.",
        "category": "cond-mat"
    },
    {
        "text": "Heat transport in quantum spin chains: the relevance of integrability: We investigate heat transport in various quantum spin chains, using the\nprojector operator technique. We find that anomalous heat transport is linked\nnot to the integrability of the Hamiltonian, but to whether it can be mapped to\na model of non-interacting fermions. Our results also suggest how seemingly\nanomalous transport may occur at low temperatures in a much wider class of\nmodels.",
        "category": "cond-mat"
    },
    {
        "text": "Affect of film thickness on the blue photoluminescence from ZnO: Zinc oxide (ZnO) films having various thicknesses were synthesized on\nsapphire substrates by thermal oxidation of Zn-metallic films in air ambient.\nX-ray diffraction (XRD) spectra indicate that the resulting films possess a\npolycrystalline hexagonal wurtzite structure without preferred orientation. For\nfilms having a thickness of 200 nm, crystal grain size was observed to decrease\nwith increasing annealing temperature up to 600C, and then increase at higher\ntemperatures. Thicker films demonstrated a modest increase in grain size as\ntemperature increased from 300C to 1200C. The influence of film thickness on\nthe optical properties was investigated using room temperature\nphotoluminescence (PL). Specifically, PL spectra indicate four emission bands:\nexcitonic ultraviolet, blue, and deep-level green and yellow emission. The\nstrongest UV emission and narrowest full width at half maximum (0.09 eV) was\nobserved for films having a thickness of 200 nm and annealed at low temperature\n(300C). The ratio of deep-level green emission to UV excitonic emission was\nobserved to decrease with decreasing annealing temperature, which is attributed\nto the generation of fewer oxygen vacancies and interstitial oxygen ions in the\nbulk. As film thickness decreased, we observed the emergence of blue emission\nand a significant red shift (0.15 eV) in the bandgap. The emergence of blue\nemission and the corresponding decrease in emission associated with bulk\ndefects when depletion width grows relative to the bulk suggests that the\norigin of the blue emission is related to the negatively charged Zinc\ninterstitials found within the deletion region near the interface.",
        "category": "cond-mat"
    },
    {
        "text": "Spectroscopic evidence for polaronic behaviour of the strong spin-orbit\n  insulator Sr$_3$Ir$_2$O$_7$: We investigate the bilayer Ruddlesden-Popper iridate Sr$_3$Ir$_2$O$_7$ by\ntemperature-dependent angle-resolved photoemission. We find a narrow-gap\ncorrelated insulator, with spectral features indicative of a polaronic ground\nstate, strikingly similar to that observed previously for the parent compounds\nof the cuprate superconductors. We additionally observe similar behaviour for\nthe single-layer cousin Sr$_2$IrO$_4$, indicating that strong electron-boson\ncoupling dominates the low-energy excitations of this exotic family of\nmaterials, and providing a microscopic link between the insulating ground\nstates of the seemingly-disparate 3d cuprates and 5d iridates.",
        "category": "cond-mat"
    },
    {
        "text": "Antioxidant activity and toxicity study of cerium oxide nanoparticles\n  stabilized with innovative functional copolymers: Oxidative stress, which is one of the main harmful mechanisms of pathologies\nincluding is-chemic stroke, contributes to both neurons and endothelial cell\ndamages, leading to vascular lesions. Although many antioxidants have been\ntested in preclinical studies, no treatment is currently available for stroke\npatients. Since cerium oxide nanoparticles (CNPs) exhibit remarkable\nantioxidant capacities, our objective is to develop an innovative coating to\nenhance CNPs biocompatibility without disrupting their antioxidant capacities\nor enhance their toxicity. This study reports the synthesis and\ncharacterization of functional polymers and their impact on the enzyme-like\ncatalytic activity of CNPs. To study the toxicity and the antioxidant\nproperties of CNPs for stroke and particularly endothelial damages, in vitro\nstudies are conducted on a cerebral endothelial cell line (bEnd.3). Despite\ntheir internalization in bEnd.3 cells, coated CNPs are devoid of cytotoxicity.\nMicroscopy studies report an intracellular localization of CNPs, more precisely\nin endosomes. All CNPs reduces glutamate-induced intracellular production of\nROS in endothelial cells but one CNP significantly reduces both the production\nof mitochondrial super-oxide anion and DNA oxidation. In vivo studies report a\nlack of toxicity in mice. This study there-fore describes and identifies\nbiocompatible CNPs with interesting antioxidant properties for ischemic stroke\nand related pathologies.",
        "category": "cond-mat"
    },
    {
        "text": "Optimal orbitals from energy fluctuations in correlated wave functions: A quantum Monte Carlo method of determining Jastrow-Slater wave functions for\nwhich the energy is stationary with respect to variations in the\nsingle-particle orbitals is presented. A potential is determined by a\nleast-squares fitting of fluctuations in the energy with a linear combination\nof one-body operators. This potential is used in a self-consistent scheme for\nthe orbitals whose solution ensures that the energy of the correlated wave\nfunction is stationary with respect to variations in the orbitals. The method\nis feasible for atoms, molecules, and solids and is demonstrated for the carbon\nand neon atoms.",
        "category": "cond-mat"
    },
    {
        "text": "Bending to kinetic energy transfer in adhesive peel front\n  micro-instability: We report an extensive experimental study of a detachment front dynamics\ninstability, appearing at microscopic scales during the peeling of adhesive\ntapes. The amplitude of this instability scales with its period as\n$A_{\\text{mss}} \\propto T_{\\text{mss}}^{1/3}$, with a pre-factor evolving\nslightly with the peel angle $\\theta$, and increasing systematically with the\nbending modulus $B$ of the tape backing. Establishing a local energy budget of\nthe detachment process during one period of this micro-instability, our\ntheoretical model shows that the elastic bending energy stored in the portion\nof tape to be peeled is converted into kinetic energy, providing a quantitative\ndescription of the experimental scaling law.",
        "category": "cond-mat"
    },
    {
        "text": "Phase stabilization by electronic entropy in plutonium: (Pu) has an unusually rich phase diagram that includes seven distinct solid\nstate phases and an unusually large 25% collapse in volume from its delta phase\nto its low temperature alpha phase via a series of structural transitions.\nDespite considerable advances in our understanding of strong electronic\ncorrelations within various structural phases of Pu and other actinides, the\nthermodynamic mechanism responsible for driving the volume collapse has\ncontinued to remain a mystery. Here we utilize the unique sensitivity of\nmagnetostriction measurements to unstable f electron shells to uncover the\ncrucial role played by electronic entropy in stabilizing delta-Pu against\nvolume collapse. We find that in contrast to valence fluctuating rare earths,\nwhich typically have a single f electron shell instability whose excitations\ndrive the volume in a single direction in temperature and magnetic field,\ndelta-Pu exhibits two such instabilities whose excitations drive the volume in\nopposite directions while producing an abundance of entropy at elevated\ntemperatures. The two instabilities imply a near degeneracy between several\ndifferent configurations of the 5f atomic shell, giving rise to a considerably\nricher behavior than found in rare earth metals. We use heat capacity\nmeasurements to establish a robust thermodynamic connection between the two\nexcitation energies, the atomic volume, and the previously reported excess\nentropy of delta-Pu at elevated temperatures.",
        "category": "cond-mat"
    },
    {
        "text": "Orbitally driven spin-singlet dimerization in $S$=1\n  La$_{4}$Ru$_{2}$O$_{10}$: Using x-ray absorption spectroscopy at the Ru-$L_{2,3}$ edge we reveal that\nthe Ru$^{4+}$ ions remain in the $S$=1 spin state across the rare 4d-orbital\nordering transition and spin-gap formation. We find using local spin density\napproximation + Hubbard U (LSDA+U) band structure calculations that the crystal\nfields in the low temperature phase are not strong enough to stabilize the\n$S$=0 state. Instead, we identify a distinct orbital ordering with a\nsignificant anisotropy of the antiferromagnetic exchange couplings. We conclude\nthat La$_{4}$Ru$_{2}$O$_{10}$ appears to be a novel material in which the\norbital physics drives the formation of spin-singlet dimers in a quasi\n2-dimensional $S$=1 system.",
        "category": "cond-mat"
    },
    {
        "text": "Phase diagram and critical behavior of the square-lattice Ising model\n  with competing nearest- and next-nearest-neighbor interactions: Using the parallel tempering algorithm and GPU accelerated techniques, we\nhave performed large-scale Monte Carlo simulations of the Ising model on a\nsquare lattice with antiferromagnetic (repulsive) nearest-neighbor(NN) and\nnext-nearest-neighbor(NNN) interactions of the same strength and subject to a\nuniform magnetic field. Both transitions from the (2x1) and row-shifted (2x2)\nordered phases to the paramagnetic phase are continuous. From our data\nanalysis, reentrance behavior of the (2x1) critical line and a bicritical point\nwhich separates the two ordered phases at T=0 are confirmed. Based on the\ncritical exponents we obtained along the phase boundary, Suzuki's weak\nuniversality seems to hold.",
        "category": "cond-mat"
    },
    {
        "text": "Light bipolarons in a system of electrons coupled to dispersive optical\n  phonons: We investigate the ground state properties of the bipolaron coupled to\nquantum dispersive optical phonons in the one-dimensional Holstein-Hubbard\nmodel. We concentrate on the interplay between the phonon dispersion and the\nCoulomb repulsion and their mutual effect on the bipolaron effective mass, the\nbinding energy, and the phase diagram. Most surprisingly, the sign of the\ncurvature of the optical phonon dispersion plays a decisive role on the\nbipolaron binding energy in the presence of the Coulomb repulsion $U$. In\nparticular, when the sign of the phonon dispersion curvature matches the sign\nof the electron dispersion curvature, the bipolaron remains bound in the strong\ncoupling limit even when $U\\to \\infty$ and the binding emanates from the\nexchange of phonons between two electrons residing on adjacent sites. At\nmoderate electron-phonon coupling a light bipolaron exists up to large values\nof $U$. Finally, an intuitive explanation of the role of the phonon dispersion\non the bipolaron binding energy is derived using the strong coupling limit\nwhere the binding emanates from the exchange of phonons between two electrons\nresiding on adjacent sites which leads to enhanced stability of bipolarons at\nelevated Coulomb repulsion.",
        "category": "cond-mat"
    },
    {
        "text": "The Berry Phase Rectification Tensor and The Solar Rectification Vector: We introduce an operational definition of the Berry Phase Rectification\nTensor as the second-order change of polarization of a material in response to\nan ideal short pulse of an electric field. Under time-reversal symmetry this\ntensor depends exclusively on the Berry phases of the Bloch bands and not their\nenergy dispersions, making it an intrinsic property to each material which\ncontains contributions from both the inter-band shift currents and the\nintra-band Berry Curvature Dipole. We also introduce the Solar Rectification\nVector as a technologically relevant figure of merit for a bulk photo-current\ngeneration under ideal black-body radiation in analogy with the classic solar\ncell model of Shockley and Queisser. We perform first-principles calculations\nof the Berry Phase Rectification Tensor and the Solar Rectification Vector for\nthe Weyl semimetal TaAs and the insulator LiAsSe2 which features large shift\ncurrents close to the peak of solar radiation intensity.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical Simulations of Trapped Bose Gases at Finite Temperatures: In this paper, we develop a numerical procedure for investigating the\ndynamics of trapped Bose gases based on the ZGN theory. The dynamical equations\nused consist of a generalized Gross-Pitaevskii equation for the condensate\norder parameter and a semiclassical kinetic equation for the thermal cloud. The\nformer is solved using a fast Fourier transform split-operator technique while\nthe Boltzmann equation is treated by means of N-body simulations. The two\ncomponents are coupled by mean fields as well as collisional processes that\ntransfer atoms between the two. This scheme has been applied to a model\nequilibration problem, dipole oscillations in isotropic traps and scissors\nmodes in anisotropic traps. In the case of the latter, the frequencies and\ndamping rates of the condensate mode have been extracted from the simulations\nfor a wide range of temperatures. Good agreement with recent experiments has\nbeen found.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of Dipole-Induced Spin Texture in an $^{87}$Rb Bose-Einstein\n  Condensate: We report the spin texture formation resulting from the magnetic\ndipole-dipole interaction in a spin-2 $^{87}$Rb Bose-Einstein condensate. The\nspinor condensate is prepared in the transversely polarized spin state and the\ntime evolution is observed under a magnetic field of 90 mG with a gradient of 3\nmG/cm using Stern-Gerlach imaging. The experimental results are compared with\nnumerical simulations of the Gross-Pitaevskii equation, which reveals that the\nobserved spatial modulation of the longitudinal magnetization is due to the\nspin precession in an effective magnetic field produced by the dipole-dipole\ninteraction. These results show that the dipole-dipole interaction has\nconsiderable effects even on spinor condensates of alkali metal atoms.",
        "category": "cond-mat"
    },
    {
        "text": "A Feshbach resonance in collisions between ultracold ground state\n  molecules: Collisional resonances are an important tool which has been used to modify\ninteractions in ultracold gases, for realizing novel Hamiltonians in quantum\nsimulations, for creating molecules from atomic gases and for controlling\nchemical reactions. So far, such resonances have been observed for atom-atom\ncollisions, atom-molecule collisions and collisions between Feshbach molecules\nwhich are very weakly bound. Whether such resonances exist for ultracold ground\nstate molecules has been debated due to the possibly high density of states\nand/or rapid decay of the resonant complex. Here we report a very pronounced\nand narrow (25 mG) Feshbach resonance in collisions between two ground state\nNaLi molecules. This molecular Feshbach resonance has two special\ncharacteristics. First, the collisional loss rate is enhanced by more than two\norders of magnitude above the background loss rate which is saturated at the\n$p$-wave universal value, due to strong chemical reactivity. Second, the\nresonance is located at a magnetic field where two open channels become nearly\ndegenerate. This implies the intermediate complex predominantly decays to the\nsecond open channel. We describe the resonant loss feature using a model with\ncoupled modes which is analogous to a Fabry-P\\'erot cavity. Our observations\nprove the existence of long-lived coherent intermediate complexes even in\nsystems without reaction barriers and open up the possibility of coherent\ncontrol of chemical reactions.",
        "category": "cond-mat"
    },
    {
        "text": "Resilience of gas-phase anharmonicity in the vibrational response of\n  adsorbed carbon monoxide and breakdown under electrical conditions: In surface catalysis, the adsorption of carbon monoxide on transition-metal\nelectrodes represents the prototype of strong chemisorption. Notwithstanding\nsignificant changes in the molecular orbitals of adsorbed CO, spectroscopic\nexperiments highlight a close correlation between the adsorbate stretching\nfrequency and equilibrium bond length for a wide range of adsorption geometries\nand substrate compositions. In this work, we study the origins of this\ncorrelation, commonly known as Badger's rule, by deconvoluting and examining\ncontributions from the adsorption environment to the intramolecular potential\nusing first-principles calculations. Noting that intramolecular anharmonicity\nis preserved upon CO chemisorption, we show that Badger's rule for adsorbed CO\ncan be expressed solely in terms of the tabulated Herzberg spectroscopic\nconstants of isolated CO. Moreover, although it had been previously established\nusing finite-cluster models that Badger's rule is not affected by electrical\nconditions, we find here that Badger's rule breaks down when the electrified\nsurface is represented as a periodic slab. Examining this breakdown in terms of\nanharmonic contributions from the effective surface charge reveals limitations\nof conventional finite-cluster models in describing electrical conditions at\nmetal electrodes.",
        "category": "cond-mat"
    },
    {
        "text": "Interaction-induced beats of Friedel oscillations in quantum wires: We analyze the spectrum of electron density oscillations in an interacting\none-dimensional electron system with an impurity. The system's inhomogeneity is\ncharacterized by different values of Fermi wave vectors $k_F=k_{L/R}$ on\nleft/right side of the scatterer, leading to a Landauer dipole formation. We\ndemonstrate, that while in the noninteracting system the Friedel oscillations\npossess only one periodicity related to the local $k_F$, say $k_L$ on the left\nside, the interplay of the interactions and the Landauer dipole generates an\nadditional peak in the spectrum of density oscillations at the counterpart\n$k_R$. Being only present in correlated systems, the position and shape of this\nspectral feature, which in coordinate space is observable as a beating pattern\nin the Friedel oscillations, reveals many important details about the nature of\ninteractions. Thus it has a potential to become an investigation tool in\ncondensed matter physics.",
        "category": "cond-mat"
    },
    {
        "text": "Non-local features of the spin-orbit exciton in Kitaev materials: A comparative resonant inelastic x-ray scattering (RIXS) study of three\nwell-known Kitaev materials is presented: $\\alpha$-Li$_2$IrO$_3$,\nNa$_2$IrO$_3$, and $\\alpha$-RuCl$_3$. Despite similar low-energy physics, these\nmaterials show distinct electronic properties, such as the large difference in\nthe size of the charge gap. The RIXS spectra of the spin-orbit exciton for\nthese materials show remarkably similar three-peak features, including sharp\nlow energy peak (peak A) as well as transitions between $j_{\\text{eff}}=1/2$\nand $j_{\\text{eff}}=3/2$ states. Comparison of experimental spectra with\ncluster calculations reveals that the observed three-peak structure reflects\nthe significant role that non-local physics plays in the electronic structure\nof these materials. In particular, the low-energy peak A arises from a\nholon-doublon pair rather than a conventional particle-hole exciton as proposed\nearlier. Our study suggests that while spin-orbit assisted Mott insulator is\nstill the best description for these materials, electron itinerancy cannot be\nignored when formulating low-energy Hamiltonian of these materials.",
        "category": "cond-mat"
    },
    {
        "text": "Comment on the energy spectrum of Tonks-Girardeau gas: Withdrawn due to major errors.",
        "category": "cond-mat"
    },
    {
        "text": "Two-channel point-contact tunneling theory of superconductors: We introduce a two-channel tunneling model to generalize the widely used BTK\ntheory of point-contact conductance between a normal metal contact and\nsuperconductor. Tunneling of electrons can occur via localized surface states\nor directly, resulting in a Fano resonance in the differential conductance\n$G=dI/dV$. We present an analysis of $G$ within the two-channel model when\napplied to soft point-contacts between normal metallic silver particles and\nprototypical heavy-fermion superconductors CeCoIn$_5$ and CeRhIn$_5$ at high\npressures. In the normal state the Fano line shape of the measured $G$ is well\ndescribed by a model with two tunneling channels and a large\ntemperature-independent background conductance. In the superconducting state a\nstrongly suppressed Andreev reflection signal is explained by the presence of\nthe background conductance. We report Andreev signal in CeCoIn$_5$ consistent\nwith standard $d_{x^2-y^2}$-wave pairing, assuming an equal mixture of\ntunneling into [100] and [110] crystallographic interfaces. Whereas in\nCeRhIn$_5$ at 1.8 and 2.0 GPa the signal is described by a $d_{x^2-y^2}$-wave\ngap with reduced nodal region, i.e., increased slope of the gap opening on the\nFermi surface. A possibility is that the shape of the high-pressure Andreev\nsignal is affected by the proximity of a line of quantum critical points that\nextends from 1.75 to 2.3 GPa, which is not accounted for in our description of\nthe heavy-fermion superconductor.",
        "category": "cond-mat"
    },
    {
        "text": "Fundamental differences between exciton and quantum dot duo: We present five major reasons why semiconductor exciton, that is, a\ncorrelated electron-hole pair in a bulk, quantum well, or quantum wire, is\nconceptually different from a pair in a quantum dot: (1) the origin of pair\nbinding, (2) the interaction with additional carriers, (3) the quantum nature\nof the pair, (4) the coupling to photon, and (5) the photon-absorption\nmechanism. Due to these differences, we should refrain from calling an\nelectron-hole pair in a quantum dot an exciton, as commonly done; we propose to\ncall it a duo. Within the same frame of chamber musics, we likewise propose to\ncall three and four carriers in a dot, a trio and a quatuor, instead of a trion\nand a biexciton.",
        "category": "cond-mat"
    },
    {
        "text": "Mechanical Theory of Nonequilibrium Coexistence and Motility-Induced\n  Phase Separation: Nonequilibrium phase transitions are routinely observed in both natural and\nsynthetic systems. The ubiquity of these transitions highlights the conspicuous\nabsence of a general theory of phase coexistence that is broadly applicable to\nboth nonequilibrium and equilibrium systems. Here, we present a general\nmechanical theory for phase separation rooted in ideas explored nearly a\nhalf-century ago in the study of inhomogeneous fluids. The core idea is that\nthe mechanical forces within the interface separating two coexisting phases\nuniquely determine coexistence criteria, regardless of whether a system is in\nequilibrium or not. We demonstrate the power and utility of this theory by\napplying it to active Brownian particles, predicting a quantitative phase\ndiagram for motility-induced phase separation in both two and three dimensions.\nThis formulation additionally allows for the prediction of novel interfacial\nphenomena, such as an increasing interface width while moving deeper into the\ntwo-phase region, a uniquely nonequilibrium effect confirmed by computer\nsimulations. The self-consistent determination of bulk phase behavior and\ninterfacial phenomena offered by this mechanical perspective provide a concrete\npath forward towards a general theory for nonequilibrium phase transitions.",
        "category": "cond-mat"
    },
    {
        "text": "Auger recombination and carrier multiplication in embedded silicon and\n  germanium nanocrystals: For Si and Ge nanocrystals (NCs) embedded in wide band-gap matrices, Auger\nrecombination (AR) and carrier multiplication (CM) lifetimes are computed\nexactly in a three-dimensional real space grid using empirical pseudopotential\nwave functions. Our results in support of recent experimental data offer new\npredictions. We extract simple Auger constants valid for NCs. We show that both\nSi and Ge NCs can benefit from photovoltaic efficiency improvement via CM due\nto the fact that under an optical excitation exceeding twice the band gap\nenergy, the electrons gain lion's share from the total excess energy and can\ncause a CM. We predict that CM becomes especially efficient for hot electrons\nwith an excess energy of about 1 eV above the CM threshold.",
        "category": "cond-mat"
    },
    {
        "text": "Fully resolved currents from quantum transport calculations: We extract local current distributions from interatomic currents calculated\nusing a fully relativistic quantum mechanical scattering formalism by\ninterpolation onto a three-dimensional grid. The method is illustrated with\ncalculations for Pt$|$Ir and Pt$|$Au multilayers as well as for thin films of\nPt and Au that include temperature-dependent lattice disorder. The current flow\nis studied in the \"classical\" and \"Knudsen\" limits determined by the sample\nthickness relative to the mean free path $\\lambda$, introducing current\nstreamlines to visualize the results. For periodic multilayers, our results in\nthe classical limit reveal that transport inside a metal can be described using\na single value of resistivity $\\rho$ combined with a linear variation of $\\rho$\nat the interface while the Knudsen limit indicates a strong spatial dependence\nof $\\rho$ inside a metal and an anomalous dip of the current density at the\ninterface which is accentuated in a region where transient shunting persists.",
        "category": "cond-mat"
    },
    {
        "text": "Melting tungsten nanoparticles: a molecular dynamics study: We report a molecular dynamics simulation of melting of tungsten (W)\nnanoparticles. The modified embedded atom method (MEAM) interatomic potentials\nare used to describe the interaction between tungsten atoms. The melting\ntemperature of unsupported tungsten nanoparticles of different sizes are found\nto decrease as the size of the particles decreases. The melting temperature\nobtained in the present study is approximately a decreasing function of inverse\nradius, in a good agreement with the predictions of thermodynamic models. We\nalso observed that the melting of a W nanoparticle is preceded by the\npremelting of its outer skin at a temperature lower than its melting\ntemperature.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic-field induced triplet superconductivity in the Hubbard model on\n  a triangular lattice: We propose theoretically that a magnetic field can realize spin-triplet\nsuperconductivity in repulsively interacting electron systems having strong\nferromagnetic spin fluctuations. We confirm the general idea for the\nlow-density Hubbard model on a triangular lattice, whose Fermi surface consists\nof disconnected pieces, by calculating the pairing susceptibility in a moderate\nmagnetic field with the quantum Monte-Carlo method combined with the dynamical\ncluster approximation.",
        "category": "cond-mat"
    },
    {
        "text": "Achieving fast oxygen diffusion in perovskites by cation ordering: The oxygen-exchange behavior has been studied in half-doped manganese and\ncobalt perovskite oxides. We have found that the oxygen diffusivity in\nGd_{0.5}Ba_{0.5}MnO_{3-\\delta} can be enhanced by orders of magnitude by\ninducing crystallographic ordering among lanthanide and alkali-earth ions in\nthe A-site sublattice. Transformation of a simple cubic perovskite, with\nrandomly occupied A-sites, into a layered crystal GdBaMn_2O_{5+x} (or\nisostructural GdBaCo_2O_{5+x} for cobalt oxide) with alternating lanthanide and\nalkali-earth planes reduces the oxygen bonding strength and provides\ndisorder-free channels for ion motion, pointing to an efficient way to design\nnew ionic conductors.",
        "category": "cond-mat"
    },
    {
        "text": "Comparative classical and ab initio Molecular Dynamics study of molten\n  and glassy germanium dioxide: A Molecular Dynamics (MD) study of static and dynamic properties of molten\nand glassy germanium dioxide is presented. The interactions between the atoms\nare modelled by the classical pair potential proposed by Oeffner and Elliott\n(OE) [Oeffner R D and Elliott S R 1998, Phys. Rev. B, 58, 14791]. We compare\nour results to experiments and previous simulations. In addition, an ab initio\nmethod, the so-called Car-Parrinello Molecular Dynamics (CPMD), is applied to\ncheck the accuracy of the structural properties, as obtained by the classical\nMD simulations with the OE potential. As in a similar study for SiO2, the\nstructure predicted by CPMD is only slightly softer than that resulting from\nthe classical MD. In contrast to earlier simulations, both the static structure\nand dynamic properties are in very good agreement with pertinent experimental\ndata. MD simulations with the OE potential are also used to study the\nrelaxation dynamics. As previously found for SiO2, for high temperatures the\ndynamics of molten GeO2 is compatible with a description in terms of mode\ncoupling theory.",
        "category": "cond-mat"
    },
    {
        "text": "Reinforcement Learning of Artificial Microswimmers: The behavior of living systems is based on the experience they gained through\ntheir interactions with the environment [1]. This experience is stored in the\ncomplex biochemical networks of cells and organisms to provide a relationship\nbetween a sensed situation and what to do in this situation [2-4]. An\nimplementation of such processes in artificial systems has been achieved\nthrough different machine learning algorithms [5, 6]. However, for microscopic\nsystems such as artificial microswimmers which mimic propulsion as one of the\nbasic functionalities of living systems [7, 8] such adaptive behavior and\nlearning processes have not been implemented so far. Here we introduce machine\nlearning algorithms to the motion of artificial microswimmers with a hybrid\napproach. We employ self-thermophoretic artificial microswimmers in a real\nworld environment [9, 10] which are controlled by a real-time microscopy system\nto introduce reinforcement learning [11-13]. We demonstrate the solution of a\nstandard problem of reinforcement learning - the navigation in a grid world.\nDue to the size of the microswimmer, noise introduced by Brownian motion if\nfound to contribute considerably to both the learning process and the actions\nwithin a learned behavior. We extend the learning process to multiple swimmers\nand sharing of information. Our work represents a first step towards the\nintegration of learning strategies into microsystems and provides a platform\nfor the study of the emergence of adaptive and collective behavior.",
        "category": "cond-mat"
    },
    {
        "text": "Simple derivation of Young, Wenzel and Cassie-Baxter equations and its\n  interpretations: In this paper we have derived Young's, Wenzel's and Cassie-Baxter's equations\nusing conceptual model rather than showing rigorous derivation to help the\nnew-comers in this field. We then pointed out that if the substrate is\ninitially hydorphilic then one can modify the surface morphology and make the\nsubstrate to become hydrophobic or superhydrophobic. But, if the substrate is\ninitially hydrophobic then one can only make it superhydrophobic but not\nhydrophilic by modifying the surface morphology using the formalisms mentioned\nin this paper",
        "category": "cond-mat"
    },
    {
        "text": "Phase diagram and neutron spin resonance of superconducting\n  NaFe$_{1-x}$Cu$_x$As: We use transport and neutron scattering to study the electronic phase diagram\nand spin excitations of NaFe$_{1-x}$Cu$_x$As single crystals. Similar to Co-\nand Ni-doped NaFeAs, a bulk superconducting phase appears near $x\\approx2\\%$\nwith the suppression of stripe-type magnetic order in NaFeAs. Upon further\nincreasing Cu concentration the system becomes insulating, culminating in an\nantiferromagnetically ordered insulating phase near $x\\approx 50\\%$. Using\ntransport measurements, we demonstrate that the resistivity in\nNaFe$_{1-x}$Cu$_x$As exhibits non-Fermi-liquid behavior near $x\\approx1.8\\%$.\nOur inelastic neutron scattering experiments reveal a single neutron spin\nresonance mode exhibiting weak dispersion along $c$-axis in\nNaFe$_{0.98}$Cu$_{0.02}$As. The resonance is high in energy relative to the\nsuperconducting transition temperature $T_{\\rm c}$ but weak in intensity,\nlikely resulting from impurity effects. These results are similar to other iron\npnictides superconductors despite the superconducting phase in\nNaFe$_{1-x}$Cu$_x$As is continuously connected to an antiferromagnetically\nordered insulating phase near $x\\approx 50\\%$ with significant electronic\ncorrelations. Therefore, electron correlations is an important ingredient of\nsuperconductivity in NaFe$_{1-x}$Cu$_x$As and other iron pnictides.",
        "category": "cond-mat"
    },
    {
        "text": "Fluid critical behavior at liquid-gas phase transition: Analytic method\n  for microscopic description: The behavior of fluids in the vicinity of the liquid-gas critical point is\nstudied within the cell fluid model framework. The analytic method for deriving\nthe equation of state of a cell fluid model in the low-temperature region\n(T<Tc) is developed using the renormalization group transformation within the\ncollective variables approach. Mathematical description within the grand\ncanonical ensemble is illustrated by an example of the Morse interaction\npotential possessing the Fourier transform. A specific feature of the proposed\nmethod lies in the possibility to use exclusively microscopic characteristics\nof a fluid (parameters of the interaction potential) for calculating\nmacroscopic quantities (pressure and other thermodynamic quantities) without\ninvolving the hard-spheres reference system. The grand partition function,\nthermodynamic potential, and equation of state of the model near the critical\npoint are derived taking into account the non-Gaussian (quartic) distribution\nof order parameter fluctuations. A nonlinear equation, which links the density\nand the chemical potential, is presented and solved. Graphs of the dependence\nof the density on the chemical potential are plotted for various values of the\nrelative temperature. The numerical estimates of the critical-point parameters\nfor potassium, obtained in addition to the estimates for sodium, are given. The\ncalculated critical-point parameters for liquid alkali metals (sodium and\npotassium) are in accord with experimental data. The coexistence curve for\nsodium is plotted and compared with other authors' data in the immediate\nvicinity of Tc, where theoretical and experimental researches are difficult to\ncarry out. The differences between the obtained results and the earlier\npublished results for T>Tc are discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Optical Response of Solid CO$_2$ as a Tool for the Determination of the\n  High Pressure Phase: We report first-principles calculations of the frequency dependent linear and\nsecond-order optical properties of the two probable extended-solid phases of\nCO$_2$--V, i.e. $I\\bar42d$ and $P2_12_12_1$. Compared to the parent $Cmca$\nphase the linear optical susceptibility of both phases is much smaller. We find\nthat $I\\bar42d$ and $P2_12_12_1$ differ substantially in their linear optical\nresponse in the higher energy regime. The nonlinear optical responses of the\ntwo possible crystal structures differ by roughly a factor of five. Since the\ndifferences in the nonlinear optical spectra are pronounced in the low energy\nregime, i.e. below the band gap of diamond, measurements with the sample inside\nthe diamond anvil cell are feasible. We therefore suggest optical experiments\nin comparison with our calculated data as a tool for the unambiguous\nidentification of the high pressure phase of CO$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Coexistence of Multifold and Multidimensional Topological Phonons in\n  KMgBO$_{3}$: Topological interpretations of phonons facilitate a new platform for novel\nconcepts in phonon physics. Though there are ubiquitous set of reports on\ntopological electronic excitations, the same for phonons are extremely limited.\nHere, we propose a new candidate material, KMgBO 3 , which showcase the\nco-existence of several multifold and multidimensional topological phonon\nexcitations, which are protected by spatial and non-spatial symmetries. This\nincludes zero dimensional double, triple and quadratic Weyl phonon nodes, one\ndimensional nodal line/loop and two dimensional doubly degenerate nodal surface\nstates. Nodal line/loop emerges from the spin- 12 phonon nodes, while the two\ndimensional doubly degenerate nodal surface arises from a combination of two\nfold screw rotational and time reversal symmetries. Application of strain\nbreaks the C 3 rotational symmetry, which annihilates the spin-1 double Weyl\nnodes, but preserves other topological features. Interestingly, strain helps to\ncreate two extra single Weyl nodes, which in turn preserve the total chirality.\nAlloying also breaks certain symmetries, destroying most of the topological\nphonon features in the present case. Thus, KMgBO 3 is a promising candidate\nwhich hosts various Weyl points, large Fermi arcs with a very clean phonon\nspectra and tunable topological phonon excitations, and hence certainly worth\nfor future theoretical/experimental investigation of topological phononics.",
        "category": "cond-mat"
    },
    {
        "text": "Switchable coupling for superconducting qubits using double resonance in\n  the presence of crosstalk: Several methods have been proposed recently to achieve switchable coupling\nbetween superconducting qubits. We discuss some of the main considerations\nregarding the feasibility of implementing one of those proposals: the\ndouble-resonance method. We analyze mainly issues related to the achievable\neffective coupling strength and the effects of crosstalk on this coupling\napproach. We also find a new, crosstalk-assisted coupling channel that can be\nan attractive alternative when implementing the double-resonance coupling\nproposal.",
        "category": "cond-mat"
    },
    {
        "text": "Variational Monte Carlo study of stripes as a function of doping in the\n  $t-t'$ Hubbard model: We perform variational Monte Carlo simulations of the single-band Hubbard\nmodel on the square lattice with both nearest ($t$) and next-nearest ($t'$)\nneighbor hoppings. Our work investigates the consequences of increasing hole\ndoping on the instauration of stripes and the behavior of the superconducting\norder parameter, with a discussion on how the two phenomena affect each other.\nWe consider two different values of the next-nearest neighbor hopping\nparameter, that are appropriate for describing cuprate superconductors. We\nobserve that stripes are the optimal state in a wide doping range; the stripe\nwavelength reduces at increasing doping, until stripes melt into a uniform\nstate for large values of doping. Superconducting pair-pair correlations,\nindicating the presence of superconductivity, are always suppressed in the\npresence of stripes. Our results suggest that the phase diagram for the\nsingle-band Hubbard model is dominated by stripes, with superconductivity being\npossible only in a narrow doping range between striped states and a\nnonsuperconducting metal.",
        "category": "cond-mat"
    },
    {
        "text": "Modified Double Exchange Model with Novel Spin and Orbital Coupling:\n  Phase Diagram of The Manganites: From a general model of the Mn oxides R_{1-x}A_{x}MnO_3, we derive an\neffective Hamiltonian in the low-energy subspace using the projection operator\nmethod, in which a novel coupling between the spin and orbital degrees of\nfreedom is included. A phase diagram for temperature T versus doping\nconcentration x is computed by means of Monte Carlo simulation. Our result is\nconsistent with experimental observations in the Mn oxides with relatively wide\nconduction band, such as Pr_{1-x}Sr_{x} MnO_{3} and La_{1-x}Sr_{x}MnO_{3}.\nAccording to the obtained orbital ordering, we also predict that the motion of\ncharge carriers transforms from three-dimensional to two-dimensional as x is\nincreased beyond a critical value.",
        "category": "cond-mat"
    },
    {
        "text": "Non-universal scaling in a model of information transmission and herd\n  behavior: We present a generalized dynamical model describing the sharing of\ninformation, and corresponding herd behavior, in a population based on the\nrecent model proposed by Eguiluz and Zimmermann. By introducing a\nsize-dependent probability for dissociation of a cluster, we show that the\nexponent characterizing the distribution of cluster sizes becomes\nmodel-dependent and non-universal. The resulting system, which provides a\nsimplified model of a financial market, yields power law behavior with an\neasily tunable exponent.",
        "category": "cond-mat"
    },
    {
        "text": "On the form of prior for constrained thermodynamic processes with\n  uncertainty: We consider the standard thermodynamic processes with constraints, but with\nadditional uncertainty about the control parameters. Motivated by inductive\nreasoning, we assign prior distribution that provides a rational guess about\nlikely values of the uncertain parameters.The priors are derived explicitly for\nboth the entropy conserving and the energy conserving processes. The proposed\nform is useful when the constraint equation cannot be treated analytically. The\ninference is performed using spin-1/2 systems as models for heat reservoirs.\nAnalytical results are derived in the high temperatures limit. Comparisons are\nfound between the estimates of thermal quantities and the optimal values\ndescribed by extremum principles. We also seek a intuitive interpretation of\nthe prior and show that it becomes uniform over the quantity which is conserved\nin the process. We find further points of correspondence between the inference\nbased approach and the thermodynamic framework.",
        "category": "cond-mat"
    },
    {
        "text": "Excitonic quantum criticality: from bilayer graphene to narrow Chern\n  bands: We study a family of excitonic quantum phase transitions describing the\nevolution of a bilayer metallic state to an inter-layer coherent state where\nexcitons condense. We argue that such transitions can be continuous and exhibit\na non-Fermi liquid counterflow response\n${\\rho_{\\mathrm{counterflow}}(\\omega)\\sim\\omega^{2/z}}$ that directly encodes\nthe dynamical critical exponent $z$. This physics is relevant to any system\nwith spin, valley, or layer degrees of freedom. We consider two contexts for\nexcitonic quantum criticality: (1) a weakly interacting graphene bilayer, and\n(2) a system of two narrow, half-filled Chern bands at zero external magnetic\nfield, with total Chern number $C_{\\mathrm{tot}}=0$, which may soon be\nrealizable in moir\\'{e} fractional quantum anomalous Hall systems. The latter\nsystem hosts a time-reversed pair of composite Fermi liquid states, and the\ncondensation of excitons of the composite fermions leads to an exotic exciton\ninsulator* state with a charge neutral Fermi surface. Our work sheds new light\non the physics of inter-layer coherence transitions in 2D materials, and it\nconstitutes the first unambiguous example of quantum critical transport in a\nclean non-Fermi liquid metal.",
        "category": "cond-mat"
    },
    {
        "text": "Bulk-like viscosity and shear thinning during dynamic compression of a\n  nanoconfined liquid: The viscosity of liquids under nanoconfinement remains controversial. Reports\nrange from spontaneous solidification to no change in the viscosity at all.\nHere, we present thorough measurements with a small-amplitude linear atomic\nforce microscopy technique and careful consideration of the confinement\ngeometry, to show that in a weakly interacting liquid, average viscosity\nremains bulk like, except for strong shear thinning once the liquid is confined\nto less than four molecular layers. Overlaid over this bulk-like viscous\nbehavior are stiffness and damping oscillations, indicating non-continuum\nbehavior, as well as an elastic response when the liquid is allowed to order in\nthe confinement gap.",
        "category": "cond-mat"
    },
    {
        "text": "Nonequilibrium Invariant Measure under Heat Flow: We provide an explicit representation of the nonequilibrium invariant measure\nfor a chain of harmonic oscillators with conservative noise in the presence of\nstationary heat flow. By first determining the covariance matrix, we are able\nto express the measure as the product of Gaussian distributions aligned along\nsome collective modes that are spatially localized with power-law tails.\nNumerical studies show that such a representation applies also to a purely\ndeterministic model, the quartic Fermi-Pasta-Ulam chain.",
        "category": "cond-mat"
    },
    {
        "text": "Localization as an entanglement phase transition in boundary-driven\n  Anderson models: The Anderson localization transition is one of the most well studied examples\nof a zero temperature quantum phase transition. On the other hand, many open\nquestions remain about the phenomenology of disordered systems driven far out\nof equilibrium. Here we study the localization transition in the prototypical\nthree-dimensional, noninteracting Anderson model when the system is driven at\nits boundaries to induce a current carrying non-equilibrium steady state.\nRecently we showed that the diffusive phase of this model exhibits extensive\nmutual information of its non-equilibrium steady-state density matrix. We show\nthat that this extensive scaling persists in the entanglement and at the\nlocalization critical point, before crossing over to a short-range (area-law)\nscaling in the localized phase. We introduce an entanglement witness for\nfermionic states that we name the mutual coherence, which, for fermionic\nGaussian states, is also a lower bound on the mutual information. Through a\ncombination of analytical arguments and numerics, we determine the finite-size\nscaling of the mutual coherence across the transition. These results further\ndevelop the notion of entanglement phase transitions in open systems, with\ndirect implications for driven many-body localized systems, as well as\nexperimental studies of driven-disordered systems.",
        "category": "cond-mat"
    },
    {
        "text": "The random force in molecular dynamics with electronic friction: The Langevin equation includes a random force to maintain equilibrium and\nprevent friction from bringing motion to a standstill; but for ballistic\nmotion, the random force is often neglected. Here, we use the Langevin equation\nfor molecular dynamics simulations of 2.76 eV H-atoms experiencing electronic\nfriction in collisions with 300 K metals, where a random force arises from\nthermal electron-hole pairs. Simulations without the random force fail\ndramatically to reproduce experiment, although the incidence energy is much\nlarger than $k_\\text{B}T$. We analyze the Ornstein-Uhlenbeck process to show\nthat this is a general property of ballistic particles experiencing friction\nunder the influence of thermal fluctuations.",
        "category": "cond-mat"
    },
    {
        "text": "Low-energy quasiparticle states at superconductor-CDW interfaces: Quasiparticle bound states are found theoretically on transparent interfaces\nof d-wave superconductors (dSC) with charge density wave solids (CDW), as well\nas s-wave superconductors (sSC) with d-density waves (DDW). These bound states\nrepresent a combined effect of Andreev reflection from the superconducting side\nand an unconventional quasiparticle Q-reflection from the density wave solid.\nIf the order parameter for a density wave state is much less than the Fermi\nenergy, bound states with almost zero energy take place for an arbitrary\norientation of symmetric interfaces. For larger values of the order parameter,\ndispersionless zero-energy states are found only on (110) interfaces. Two\ndispersive energy branches of subgap quasiparticle states are obtained for\n(100) symmetric interfaces. Andreev low-energy bound states, taking place in\njunctions with CDW or DDW interlayers, result in anomalous junction properties,\nin particular, the low-temperature behavior of the Josephson critical current.",
        "category": "cond-mat"
    },
    {
        "text": "Theory and Simulation of Multiphase Polymer Systems: The theory of multiphase polymer systems has a venerable tradition. The\n'classical' theory of polymer demixing, the Flory-Huggins theory, was developed\nalready in the forties of the last century. It is still the starting point for\nmost current approaches -- be they improved theories for polymer\n(im)miscibility that take into account the microscopic structure of blends more\naccurately, or sophisticated field theories that allow to study inhomogeneous\nmulticomponent systems of polymers with arbitrary architectures in arbitrary\ngeometries. In contrast, simulations of multiphase polymer systems are\nrelatively young. They are still limited by the fact that one must simulate a\nlarge number of large molecules in order to obtain meaningful results. Both\npowerful computers and smart modeling and simulation approaches are necessary\nto overcome this problem.\n  This article gives an overview over the state-of-the art in both areas,\ntheory and simulation. While the theory has reached a fairly mature stage by\nnow, and many aspects of it are covered in textbooks on polymer physics, the\ninformation on simulations is much more scattered. This is why some effort has\nbeen invested into putting together a representative list of references in this\narea (up to the year of 2008) -- which is of course still far from complete.",
        "category": "cond-mat"
    },
    {
        "text": "Stirring by swimmers in confined microenvironments: We consider the tracer diffusion $D_{rr}$ that arises from the run-and-tumble\nmotion of low Reynolds number swimmers, such as bacteria. In unbounded dilute\nsuspensions, where the dipole swimmers move in uncorrelated runs of length\n$\\lambda$, an exact solution showed that $D_{rr}$ is independent of $\\lambda$.\nHere we verify this result in numerical simulations for a particular model\nswimmer, the spherical squirmer. We also note that in confined\nmicroenvironments, such as microscopic droplets, microfluidic devices and\nbacterial microzones in marine ecosystems, the size of the system can be\ncomparable to $\\lambda$. We show that this effect alone reduces the value of\n$D_{rr}$ in comparison to its bulk value, and predict a scaling form for its\nrelative decrease.",
        "category": "cond-mat"
    },
    {
        "text": "Universality of One-Dimensional Heat Conductivity: We show analytically that the heat conductivity of oscillator chains diverges\nwith system size N as N^{1/3}, which is the same as for one-dimensional fluids.\nFor long cylinders, we use the hydrodynamic equations for a crystal in one\ndimension. This is appropriate for stiff systems such as nanotubes, where the\neventual crossover to a fluid only sets in at unrealistically large N. Despite\nthe extra equation compared to a fluid, the scaling of the heat conductivity is\nunchanged. For strictly one-dimensional chains, we show that the dynamic\nequations are those of a fluid at all length scales even if the static order\nextends to very large N. The discrepancy between our results and numerical\nsimulations on Fermi-Pasta-Ulam chains is discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Nonadiabatic Channels in the Superconducting Pairing of Fullerides: We show the intrinsic inconsistency of the conventional phonon mediated\ntheory of superconductivity in relation to the observed properties of\nRb$_3$C$_{60}$. The recent, highly accurate measurement of the carbon isotope\ncoefficient $\\alpha_{\\rm C}=0.21$, together with the high value of $T_c$ (30 K)\nand the very small Fermi energy $E_{\\rm F}$ (0.25 eV), unavoidably implies the\nopening of nonadiabatic channels in the superconducting pairing. We estimate\nthese effects and show that they are actually the key elements for the high\nvalue of $T_c$ in these materials compared to the very low values of graphite\nintercalation compounds.",
        "category": "cond-mat"
    },
    {
        "text": "Effects of turbulent transfer on the critical behaviour: Critical behaviour of two systems, subjected to the turbulent mixing, is\nstudied by means of the field theoretic renormalization group. The first\nsystem, described by the equilibrium model A, corresponds to relaxational\ndynamics of a non-conserved order parameter. The second one is the strongly\nnonequilibrium reaction-diffusion system, known as Gribov process or directed\npercolation process. The turbulent mixing is modelled by the stochastic\nNavier-Stokes equation with random stirring force with the correlator \\propto\n\\delta(t-t') p^{4-d-y}, where p is the wave number, d is the space dimension\nand y the arbitrary exponent. It is shown that, depending on the relation\nbetween y and d, the systems exhibit various types of critical behaviour. In\naddition to known regimes (original systems without mixing and passively\nadvected scalar field), existence of new strongly nonequilibrium universality\nclasses is established, and the corresponding critical dimensions are\ncalculated to the first order of the double expansion in y and \\epsilon=4-d\n(one-loop approximation).",
        "category": "cond-mat"
    },
    {
        "text": "Isostructural Metal-Insulator Transition Driven by Dimensional-Crossover\n  in SrIrO3 Heterostructures: Dimensionality reduction induced metal-insulator transitions in oxide\nheterostructures are usually coupled with structural and magnetic phase\ntransitions, which complicate the interpretation of the underlying physics.\nTherefore, achieving isostructural MIT is of great importance for fundamental\nphysics and even more for applications. Here, we report an isostructural\nmetal-insulator transition driven by dimensional-crossover in spin-orbital\ncoupled SrIrO3 films. By using in-situ pulsed laser deposition and\nangle-resolved photoemission spectroscopy, we synthesized and investigated the\nelectronic structure of SrIrO3 ultrathin films with atomic-layer precision.\nThrough inserting orthorhombic CaTiO3 buffer layers, we demonstrate that the\ncrystal structure of SrIrO3 films remains bulk-like with similar oxygen\noctahedra rotation and tilting when approaching the ultrathin limit. We observe\nthat a dimensional-crossover metal-insulator transition occurs in isostructural\nSrIrO3 films. Intriguingly, we find the bandwidth of Jeff=3/2 states reduces\nwith lowering the dimensionality and drives the metal-insulator transition. Our\nresults establish a bandwidth controlled metal-insulator transition in the\nisostructural SrIrO3 thin films.",
        "category": "cond-mat"
    },
    {
        "text": "Role of interactions in 87Rb-40K Bose-Fermi mixtures in a 3d optical\n  lattice: We investigate the effect of interspecies interaction on a degenerate mixture\nof bosonic 87Rb and fermionic 40K atoms in a three-dimensional optical lattice\npotential. Using a Feshbach resonance, the 87Rb-40K interaction is tuned over a\nwide range. Through an analysis of the 87Rb momentum distribution, we find a\npronounced asymmetry between strong repulsion and strong attraction. In the\nlatter case, the Bose-Hubbard parameters are renormalized due to self-trapping,\nleading to a marked shift in the superfluid to Mott insulator transition with\nincreasing Bose-Fermi interaction.",
        "category": "cond-mat"
    },
    {
        "text": "BEC phase diagram of a $^{87}$Rb trapped gas in terms of macroscopic\n  thermodynamic parameters: We measure the phase diagram of a $^{87}$Rb Bose gas in a harmonic trap in\nterms of macroscopic parameters obtained from the spatial distribution of\natoms. Considering the relevant variables as size of the cloud ${\\cal V}$,\nnumber of atoms $N$ and temperature $T$, a novel parameter $\\Pi = \\Pi(N,{\\cal\nV},T)$ is introduced to characterize the overall pressure of the system. We\nconstruct the phase diagram ($\\Pi$ vs $T$) identifying new features related to\nBose-Einstein condensation (BEC) transition in a trapped gas. A thermodynamic\ndescription of the phase transition based on purely macroscopic parameters,\nprovide us with properties that do not need the local density approximation. An\nunexpected consequence of this analysis is the suggestion that BEC appears as a\ncontinuous third-order phase transition instead of being a second-order one.",
        "category": "cond-mat"
    },
    {
        "text": "Topological critical states and anomalous electronic transmittance in\n  one dimensional quasicrystals: Due to the absence of periodic length scale, electronic states and their\ntopological properties in quasicrystals have been barely understood. Here, we\nfocus on one dimensional quasicrystal and reveal that their electronic critical\nstates are topologically robust. Based on tiling space cohomology, we exemplify\nthe case of one dimensional aperiodic tilings especially Fibonacci quasicrystal\nand prove the existence of topological critical states at zero energy.\nFurthermore, we also show exotic electronic transmittance behavior near such\ntopological critical states. Within the perturbative regime, we discuss lack of\ntranslational symmetries and presence of topological critical states lead to\nunconventional scaling behavior in transmittance. Considering both analytic\nanalysis and numerics, electronic transmittance is computed in cases where the\nsystem is placed in air or is connected by semi-infinite periodic leads.\nFinally, we also discuss generalization of our analysis to other quasicrystals.\nOur findings open a new class of topological quantum states which solely exist\nin quasicrystals due to exotic tiling patterns in the absence of periodic\nlength scale, and their anomalous electronic transport properties applicable to\nmany experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Synthesis and characterization of the infinite-layer superconductor\n  Sr_{0.9}La_{0.1}CuO_{2}: We report the high-pressure synthesis of the electron-doped infinite-layer\nsuperconductor Sr_{0.9}La_{0.1}CuO_{2}. A Rietveld analysis using X-ray powder\ndiffraction data showed that, within the resolution of the measurement, the\nsample was purely an infinite-layer structure without any discernible\nimpurities. The superconducting volume fraction and the transition width were\ngreatly improved compared to those in the previous reports. Also the\nirreversibility field line was much higher than that of (La,Sr)_{2}CuO_{4}. The\nhigher value seems to originate from the strong interlayer coupling due to the\nreduced average distance between the CuO_{2} planes.",
        "category": "cond-mat"
    },
    {
        "text": "Preemptive nematic order, pseudogap, and orbital order in the iron\n  pnictides: Starting from a microscopic itinerant model, we derive and analyze the\neffective low-energy model for collective magnetic excitations in the iron\npnictides. We show that the stripe magnetic order is generally preempted by an\nIsing-nematic order which breaks $C_{4}$ lattice symmetry but preserves O(3)\nspin-rotational symmetry. This leads to a rich phase diagram as function of\ndoping, pressure, and elastic moduli, displaying split magnetic and nematic\ntri-critical points. The nematic transition may instantly bring the system to\nthe verge of a magnetic transition, or it may occur first, being followed by a\nmagnetic transition at a lower temperature. In the latter case, the preemptive\nnematic transition is accompanied by either a jump or a rapid increase of the\nmagnetic correlation length, triggering a pseudogap behavior associated with\nmagnetic precursors. Furthermore, due to the distinct orbital character of each\nFermi pocket, the nematic transition also induces orbital order. We compare our\nresults to various experiments, showing that they correctly address the changes\nin the character of the magneto-structural transition across the phase diagrams\nof different compounds, as well as the relationship between the orthorhombic\nand magnetic order parameters.",
        "category": "cond-mat"
    },
    {
        "text": "Optical probing of correlation driven liquid-to-insulator transition in\n  2D electron gas: We study the quantum Hall liquid and the metal-insulator transition in a high\nmobility two dimensional electron gas, by means of photoluminescence and\nmagneto-transport. In the integer and fractional regime at nu > 1/3, analyzing\nthe emission energy dispersion we probe the magneto-Coulomb screening and the\nhidden symmetry of the electron liquid. In the fractional regime above above nu\n=1/3 the system undergoes the metal-to-insulator transition, and in the\ninsulating phase the dispersion becomes linear with evidence of an increased\nrenormalized mass.",
        "category": "cond-mat"
    },
    {
        "text": "Colossal pressure-induced softening in scandium fluoride: The counter-intuitive phenomenon of pressure-induced softening in materials\nis likely to be caused by the same dynamical behaviour that produces negative\nthermal expansion. Through a combination of molecular dynamics simulation on an\nidealised model and neutron diffraction at variable temperature and pressure,\nwe show the existence of extraordinary and unprecedented pressure-induced\nsoftening in the negative thermal expansion material scandium fluoride,\nScF$_3$, with values of the pressure-derivative of the bulk modulus $B$,\n$B^\\prime = \\partial B / \\partial P$, reaching as low as $-40 \\pm 1$.",
        "category": "cond-mat"
    },
    {
        "text": "First-principles study of magnetic structures of triangular\n  antiferromagnets NaYbS$_2$ and NaYbO$_2$: We investigate the magnetic interactions in triangular rare-earth\ndelafossites materials NaYbO$_2$ and NaYbS$_2$ via first-principles\ncalculations. The calculated Curie-Weiss temperatures are in good agreement\nwith experiments. We perform classical Monte Carlo simulations of the two\ncompounds using the extracted exchange parameters. We find that if only the\nnearest neighbor interactions are considered, the magnetic ground states of\nNaYbO$_2$ and NaYbS$_2$ are a stripe and a planar 120\\degree~ N\\'{e}el state,\nrespectively. The simulated transition temperatures are much higher than the\nlowest experimental temperatures, where no magnetic ordering was observed.\nHowever, we show by adding suitable second neighbor interactions, the {\\it\nclassical} magnetic ground state of NaYbO$_2$ becomes to the $Z_2$ vortex\nphase, and the simulated specific heat $C_v$ are very similar to the\nexperimental observations, with no obvious phase transition down to the\nextremely low temperature.",
        "category": "cond-mat"
    },
    {
        "text": "Superconductivity From Confinement of Singlets in Metal Oxides: The Yang-Mills description of phonons and the consequent structure of\nelectron liquids in strongly anharmonic crystals such as metal oxides is shown\nto yield an attractive electron-phonon interaction, and thus an instability\ntowards the formation of bound states, which can condense to form a\nsuperconductor. This mechanism differs significantly from the pairing mechanism\nof conventional superconductivity: the ground state from which\nsuperconductivity emerges is a many-body state of paired electrons and holes\nwhich is not amenable to a quasiparticle description, and whose properties are\nsimilar to those seen in the Cuprate high temperature superconductors.\nConfinement arises because the electron liquid structure acts as a source for\nYang-Mills bosons, and not the traditional longitudinal density waves of BCS\npairing.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic and magneto-transport characterization of (Ga,Mn)(Bi,As)\n  epitaxial layers: High-quality layers of the (Ga,Mn)(Bi,As) quaternary compound semiconductor\nhave been grown by the low-temperature molecular-beam epitaxy technique. An\neffect of Bi incorporation into the (Ga,Mn)As ferromagnetic semiconductor and\nthe post-growth annealing treatment of the layers have been investigated\nthrough examination of their magnetic and magneto-transport properties.\nSignificant enhancement of the planar Hall effect magnitude upon addition of Bi\ninto the layers is interpreted as a result of increased spin-orbit coupling in\nthe (Ga,Mn)(Bi,As) layers.",
        "category": "cond-mat"
    },
    {
        "text": "Point tension in adsorption at a chemically inhomogeneous substrate in\n  two dimensions: We study adsorption of liquid at a one-dimensional substrate composed of a\nsingle chemical inhomogeneity of width $2L$ placed on an otherwise homogeneous,\nplanar, solid surface. The excess point free energy $\\eta (L,T)$ associated\nwith the adsorbed layer's inhomogeneity induced by the substrate's chemical\nstructure is calculated within exact continuum transfer-matrix approach. It is\nshown that the way $\\eta (L,T)$ varies with $L$ depends sensitively on the\ntemperature regime. It exhibits logarithmic divergence as a function of $L$ in\nthe limit $L\\to\\infty$ for temperatures such that the chemical inhomogeneity is\ncompletely wetted by the liquid. In the opposite case $\\eta (L,T)$ converges\nfor large $L$ to $2\\eta_0$, where $\\eta_0$ is the corresponding point tension,\nand the dominant $L$-dependent correction to $2\\eta_0$ decays exponentially.\nThe interaction between the liquid layer inhomogeneities at $-L$ and $L$ for\nthe two temperature regimes is discussed and compared to earlier mean-field\ntheory predictions.",
        "category": "cond-mat"
    },
    {
        "text": "Antivortices due to competing orbital and paramagnetic pair-breaking\n  effects: Thermodynamically stable vortex-antivortex structures in a\nquasi-two-dimensional superconductor in a tilted magnetic field are predicted.\nFor this geometry, both orbital and spin pair-breaking effects exist, with\ntheir relative strength depending on the tilt angle \\Theta. The spectrum of\npossible states contains as limits the ordinary vortex state (for large \\Theta)\nand the Fulde-Ferrell-Larkin-Ovchinnikov state (for \\Theta=0). The\nquasiclassical equations are solved near H_{c2} for arbitrary \\Theta and it is\nshown that stable states with coexisting vortices and antivortices exist in a\nsmall interval close to \\Theta=0. The results are compared with recent\npredictions of antivortices in mesoscopic samples.",
        "category": "cond-mat"
    },
    {
        "text": "Interplay of two $E_g$ orbitals in Superconducting La$_3$Ni$_2$O$_7$\n  Under Pressure: The discovery of high-$T_c$ superconductivity (SC) in La$_3$Ni$_2$O$_7$ (LNO)\nhas aroused a great deal of interests. Previously, it was proposed that the\nNi-$3d_{z^2}$ orbital is crucial to realize the high-$T_c$ SC in LNO: The\npreformed Cooper pairs therein acquire coherence via hybridization with the\n$3d_{x^2-y^2}$ orbital to form the SC. However, we held a different viewpoint\nthat the interlayer pairing $s$-wave SC is induced by the $3d_{x^2-y^2}$\norbital, driven by the strong interlayer superexchange interaction. To include\neffects from both $E_g$-orbitals , we establish a two-orbital bilayer $t$-$J$\nmodel. Our calculations reveal that due to the no-double-occupancy constraint,\nthe $3d_{x^2-y^2}$ band and the $3d_{z^2}$ bonding band are flattened by a\nfactor of about 2 and 10, respectively, which is consistent with recent\nangle-resolved-photo-emission-spectroscopy measurements. Consequently, a high\ntemperature SC can be hardly induced in the $3d_{z^2}$-orbital due to the\ndifficulty to develop phase coherence. However, it can be easily achieved by\nthe $3d_{x^2-y^2}$ orbital under realistic interaction strength. With electron\ndoping, the $3d_{z^2}$-band gradually dives below the Fermi level, but $T_c$\ncontinues to enhance, suggesting that it is not necessary for the high-$T_c$ SC\nin LNO. With hole doping, $T_c$ initially drops and then rises, accompanied by\nthe crossover from the BCS to BEC-type superconducting transitions.",
        "category": "cond-mat"
    },
    {
        "text": "Percolation and jamming of linear $k$-mers on square lattice with\n  defects: effect of anisotropy: We study the percolation and jamming of rods ($k$-mers) on a square lattice\nthat contains defects. The point defects are placed randomly and uniformly on\nthe substrate before deposition of the rods. The general case of unequal\nprobabilities for orientation of depositing of rods along different directions\nof the lattice is analyzed. Two different models of deposition are used. In the\nrelaxation random sequential adsorption model (RRSA), the deposition of rods is\ndistributed over different sites on the substrate. In the single cluster\nrelaxation model (RSC), the single cluster grows by the random accumulation of\nrods on the boundary of the cluster. For both models, a suppression of growth\nof the infinite cluster at some critical concentration of defects $d_c$ is\nobserved. In the zero defect lattices, the jamming concentration $p_j$ (RRSA)\nand the density of single clusters $p_s$ (RSC) decrease with increasing length\nrods and with a decrease in the order parameter. For the RRSA model, the value\nof $d_c$ decreases for short rods as the value of $s$ increases. For longer\nrods, the value of $d_c$ is almost independent of $s$. Moreover, for short\nrods, the percolation threshold is almost insensitive to the defect\nconcentration for all values of $s$. For the RSC model, the growth of clusters\nwith ellipse-like shapes is observed for non-zero values of $s$. The density of\nthe clusters $p_s$ at the critical concentration of defects $d_c$ depends in a\ncomplex manner on the values of $s$ and $k$. For disordered systems, the value\nof $p_s$ tends towards zero in the limits of the very long rods and very small\ncritical concentrations $d_c \\to 0$. In this case, the introduction of defects\nresults in a suppression of rods stacking and in the formation of `empty' or\nloose clusters with very low density. On the other hand, denser clusters are\nformed for ordered systems.",
        "category": "cond-mat"
    },
    {
        "text": "Detection of short DNA sequences with DNA nanopores: Several studies suggest strong correlation between different types of cancer\nand the relative concentration of short circulating RNA sequences (miRNA).\nBecause of short length and low concentration, miRNA detection is not easy.\nStandard methods such as RT-PCR require both the standard PCR amplification\nstep and a preliminary additional step of reverse transcription. In this paper,\nwe investigate the use of DNA nanopores as a tool to detect short\noligonucleotide sequences at the single molecule level. These nanostructures\nshow two different conformations depending on the presence of DNA analogues of\nmiRNA sequences. By monitoring current across a lipid bilayer, we show that\nthis change of conformation translates to different levels of conductivity.",
        "category": "cond-mat"
    },
    {
        "text": "Testing self-energy embedding theory in combination with GW: We present a theoretical framework and implementation details for self-energy\nembedding theory (SEET) with the GW approximation for the treatment of weakly\ncorrelated degrees of freedom and configuration interactions solver for handing\nthe strongly correlated degrees. On a series of molecular examples, for which\nthe exact results are known within a given basis, we demonstrate that\nSEET(CI/GW) is a systematically improvable and well controlled method capable\nof giving accurate results and well behaved causal self-energies and Green's\nfunctions. We compare the theoretical framework of SEET(CI/GW) to that of\nGW+DMFT and comment on differences between these to approaches that aim to\ntreat both strongly and weakly correlated simultaneously.",
        "category": "cond-mat"
    },
    {
        "text": "Synchronization in dynamical networks of locally coupled self-propelled\n  oscillators: Systems of mobile physical entities exchanging information with their\nneighborhood can be found in many different situations. The understanding of\ntheir emergent cooperative behaviour has become an important issue across\ndisciplines, requiring a general conceptual framework in order to harvest the\npotential of these systems. We study the synchronization of coupled oscillators\nin time-evolving networks defined by the positions of self-propelled agents\ninteracting in real space. In order to understand the impact of mobility in the\nsynchronization process on general grounds, we introduce a simple model of\nself-propelled hard disks performing persistent random walks in 2$d$ space and\ncarrying an internal Kuramoto phase oscillator. For non-interacting particles,\nself-propulsion accelerates synchronization. The competition between agent\nmobility and excluded volume interactions gives rise to a richer scenario,\nleading to an optimal self-propulsion speed. We identify two extreme dynamic\nregimes where synchronization can be understood from theoretical\nconsiderations. A systematic analysis of our model quantifies the departure\nfrom the latter ideal situations and characterizes the different mechanisms\nleading the evolution of the system. We show that the synchronization of\nlocally coupled mobile oscillators generically proceeds through coarsening\nverifying dynamic scaling and sharing strong similarities with the phase\nordering dynamics of the 2$d$ XY model following a quench. Our results shed\nlight into the generic mechanisms leading the synchronization of mobile agents,\nproviding a efficient way to understand more complex or specific situations\ninvolving time-dependent networks where synchronization, mobility and excluded\nvolume are at play.",
        "category": "cond-mat"
    },
    {
        "text": "Scaling of 1/f noise in tunable break-junctions: We have studied the $1/f$ voltage noise of gold nano-contacts in\nelectromigrated and mechanically controlled break-junctions having resistance\nvalues $R$ that can be tuned from 10 $\\Omega$ (many channels) to 10 k$\\Omega$\n(single atom contact). The noise is caused by resistance fluctuations as\nevidenced by the $S_V\\propto V^2$ dependence of the power spectral density\n$S_V$ on the applied DC voltage $V$. As a function of $R$ the normalized noise\n$S_V/V^2$ shows a pronounced cross-over from $\\propto R^3$ for low-ohmic\njunctions to $\\propto R^{1.5}$ for high-ohmic ones. The measured powers of 3\nand 1.5 are in agreement with $1/f$-noise generated in the bulk and reflect the\ntransition from diffusive to ballistic transport.",
        "category": "cond-mat"
    },
    {
        "text": "Statistical scattering of waves in disordered waveguides: Universal\n  Properties: The statistical theory of certain complex wave interference phenomena, like\nthe statistical fluctuations of transmission and reflection of waves, is of\nconsiderable interest in many fields of physics. In this article we shall be\nmainly interested in those situations where the complexity derives from the\nquenched randomness of scattering potentials, as in the case of disordered\nconductors, or, more in general, disordered waveguides. In studies performed in\nsuch systems one has found remarkable statistical regularities, in the sense\nthat the probability distribution for various macroscopic quantities involves a\nrather small number of relevant physical parameters, while the rest of the\nmicroscopic details serves as mere \"scaffolding\". We shall review past work in\nwhich this feature was captured following a maximum-entropy approach, as well\nas later studies in which the existence of a limiting distribution, in the\nsense of a generalized central-limit theorem, has been actually demonstrated.\nWe then describe a microscopic potential model that was developed recently,\nwhich gives rise to a further generalization of the central-limit theorem and\nthus to a limiting macroscopic statistics.",
        "category": "cond-mat"
    },
    {
        "text": "Multilayer Pt/Al Based Ohmic contacts for AlGaN/GaN Heterostructures\n  Stable up to 600oC Ambient Air: In this paper, we present a Pt/Al multilayer stack-based ohmic contact\nmetallization for AlGaN/GaN heterostructures. CTLM structures were fabricated\nto assess the electrical properties of the proposed metallization. The\nfabricated stack shows excellent stability after more than 100 hours of\ncontinuous aging at 600oC in air. Measured I-V characteristics of the\nfabricated samples show excellent linearity after the aging. The Pt/Al-based\nmetallization shows great potential for future device and sensor applications\nin extreme environment conditions.",
        "category": "cond-mat"
    },
    {
        "text": "Simulating Met-Enkephalin With Population Annealing Molecular Dynamics: Met-enkephalin, one of the smallest opiate peptides and an important\nneurotransmitter, is a widely used benchmarking problem in the field of\nmolecular simulation. Through its range of possible low-temperature\nconformations separated by free-energy barriers it was previously found to be\nhard to thermalize using straight canonical molecular dynamics simulations.\nHere, we demonstrate how one can use the recently proposed population annealing\nmolecular dynamics scheme to overcome these difficulties. We show how the use\nof multi-histogram reweighting allows one to accurately estimate the density of\nstates of the system and hence derive estimates such as the potential energy as\nquasi continuous functions of temperature. We further investigate the\nfree-energy surface as a function of end-to-end distance and radius-of-gyration\nand observe two distinct basins of attraction.",
        "category": "cond-mat"
    },
    {
        "text": "Structural transformations in porous glasses under mechanical loading.\n  I. Tension: The evolution of porous structure and mechanical properties of binary glasses\nunder tensile loading were examined using molecular dynamics simulations. We\nconsider vitreous systems obtained in the process of phase separation after a\nrapid isochoric quench of a glass-forming liquid to a temperature below the\nglass transition. The porous structure in undeformed samples varies from a\nconnected porous network to a random distribution of isolated pores upon\nincreasing average glass density. We find that at small strain, the elastic\nmodulus follows a power-law dependence on the average glass density and the\npore size distribution remains nearly the same as in quiescent samples. Upon\nfurther loading, the pores become significantly deformed and coalesce into\nlarger voids that leads to formation of system-spanning empty regions\nassociated with breaking of the material.",
        "category": "cond-mat"
    },
    {
        "text": "NMR relaxation and rattling phonons in type-I Ba8Ga16Sn30 clathrate: Atomic motion of guest atoms inside semiconducting clathrate cages is\nconsidered as an important source for the glasslike thermal behavior.69Ga and\n71Ga Nuclear Magnetic Resonance (NMR) studies on type-I Ba8Ga16Sn30 show a\nclear low temperature relaxation peak attributed to the influence of Ba\nrattling dynamics on the framework-atom resonance, with a quadrupolar\nrelaxation mechanism as the leading contribution. The data are analyzed using a\ntwo-phonon Raman process, according to a recent theory involving localized\nanharmonic oscillators. Excellent agreement is obtained using this model, with\nthe parameters corresponding to a uniform array of localized oscillators with\nvery large anharmonicity.",
        "category": "cond-mat"
    },
    {
        "text": "Residual entropy from temperature incremental Monte Carlo method: Residual entropy, indicative of the degrees of freedom in a system at\nabsolute zero, is a cornerstone for understanding quantum and classical ground\nstates. Despite its critical role in elucidating low-temperature phenomena and\nground state degeneracy, accurately quantifying residual entropy remains a\nformidable challenge due to significant computational hurdles. In this Letter,\nwe introduce the Temperature Incremental Monte Carlo (TIMC) method, our novel\nsolution crafted to surmount these challenges. The TIMC method incrementally\ncalculates the partition function ratio of neighboring temperatures within\nMonte Carlo simulations, enabling precise entropy calculations and providing\ninsights into a spectrum of other temperature-dependent observables in a single\ncomputational sweep of temperatures. We have rigorously applied TIMC to a\nvariety of complex systems, such as the frustrated antiferromagnetic Ising\nmodel on both C60 and 2D triangular lattices, the Newman-Moore spin glass\nmodel, and a 2D quantum transverse field Ising model. Notably, our method\nsurmounts the traditional obstacles encountered in partition function\nmeasurements when mapping $d$-dimensional quantum models to $d+1$-dimensional\nclassical counterparts. The TIMC method's finesse in detailing entropy across\nthe entire temperature range enriches our comprehension of critical phenomena\nin condensed matter physics. This includes insights into spin glasses, phases\nexhibiting spontaneous symmetry breaking, topological states of matter and\nfracton phases. Our approach not only advances the methodology for probing the\nentropic landscape of such systems but also paves the way for exploring their\nbroader thermodynamic and quantum mechanical properties.",
        "category": "cond-mat"
    },
    {
        "text": "Extracting the Dispersion of Periodic Lossless LC Circuits Using White\n  Noise: The spectral energy density (SED) method is used to obtain the phonon\ndispersion of materials in molecular dynamics codes, e.g., LAMMPS. We show how\nthe electric analog of the SED method can be done using commercial circuit\nsimulators to find the dispersion of periodic lossless LC circuits. The purpose\nof this article is (a) to demonstrate how SED proves useful, should the\nanalytic methods of calculating dispersion of a circuit render difficult e.g.,\ndue to nonlinearity or having large number of elements in each unit-cell, and\n(b) to show how the concepts like Brillouin zone (BZ), dispersion (or band\nstructure), zone folding, gap formation, and avoided crossing can be taught to\nstudents of electrical engineering by highlighting the analogies between\nphonons and periodic circuits. This analogy also suggests that thermal devices,\ne.g., heat rectifiers can be simulated and understood using commercial circuit\nsimulators.",
        "category": "cond-mat"
    },
    {
        "text": "First observation of bright solitons in bulk superfluid He-4: The existence of bright solitons in bulk superfluid He-4 is demonstrated by\ntime-resolved shadowgraph i maging experiments and density functional theory\n(DFT) calculations. The initial liquid compression that leads to the creation\nof non-linear waves is produced by rapidly expanding plasma from laser\nablation. Af ter the leading dissipative period, these waves transform into\nbright solitons, which exhibit three chara cteristic features: dispersionless\npropagation, negligible interaction in two-wave collision, and direct\ndependence between soliton amplitude and the propagation velocity. The\nexperimental observations are supp orted by DFT calculations, which show rapid\nevolution of the initially compressed liquid into bright soli tons. At high\namplitudes, solitons become unstable and break down into dispersive shock\nwaves.",
        "category": "cond-mat"
    },
    {
        "text": "Thermodynamics of the multi-component dimerizing hard-sphere Yukawa\n  mixture in the associative mean spherical approximation: Explicit analytical expressions for Helmholtz free energy, chemical\npotential, entropy and pressure of the multi-component dimerizing Yukawa\nhard-sphere fluid are presented. These expressions are written in terms of the\nBlum's scaling parameter $\\Gamma$, which follows from the solution of the\nassociative mean spherical approximation (AMSA) for the model with factorized\nYukawa coefficients. In this case solution of the AMSA reduces to the solution\nof only one nonlinear algebraic equation for $\\Gamma$. This feature enables the\ntheory to be used in the description of the thermodynamical properties of\nassociating fluids with arbitrary number of components, including the limiting\ncase of polydisperse fluids.",
        "category": "cond-mat"
    },
    {
        "text": "Electrical Transport Property of ZnO Thin Films in High H2 Pressure up\n  to 20 bar: We have investigated the H2 pressure-dependent (from vacuum to 20 bar)\ncurrent-voltage characteristics of ZnO thin films prepared by spin coating\nmethod. The gas pressure effect on conductance (G) was subtracted using He gas.\nThe G increased as applying 2 bar of H2 pressure, and then it monotonously\ndecreased with the further increment of H2 pressure. Using X-ray diffraction\npatterns and X-ray photoelectron spectroscopy before and after H2 exposure, we\nfound that the H2 spillover effect plays an important role in the variation of\nG of ZnO film.",
        "category": "cond-mat"
    },
    {
        "text": "Ferromagnetism and Canted Spin Phase in AlAs/GaMnAs Single Quantum\n  Wells: Monte Carlo Simulation: The magnetic order resulting from a confinement-adapted\nRuderman-Kittel-Kasuya-Yosida indirect exchange between magnetic moments in the\nmetallic phase of a AlAs/Ga(1-x)Mn(x)As quantum well is studied by Monte Carlo\nsimulation. This coupling mechanism involves magnetic moments and carriers\n(holes), both coming from the same Mn(2+) ions. It leads to a paramagnetic, a\nferromagnetic, or a canted spin phase, depending on the carrier concentration,\nand on the magnetic layer width. It is shown that high transition temperatures\nmay be obtained.",
        "category": "cond-mat"
    },
    {
        "text": "Fate of spinons at the Mott point: Gapless spin liquids have recently been observed in several frustrated Mott\ninsulators, with elementary spin excitations - \"spinons\" - reminiscent of\ndegenerate Fermi systems. However, their precise role at the Mott point, where\ncharge fluctuations begin to proliferate, remains controversial and\nill-understood. Here we present the simplest theoretical framework that treats\nthe dynamics of emergent spin and charge excitations on the same footing,\nproviding a new physical picture of the Mott metal-insulator transition at half\nfiling. We identify a generic orthogonality mechanism leading to strong damping\nof spinons, arising as soon as the Mott gap closes. Our results indicates that\nspinons should not play a significant role within the high-temperature quantum\ncritical regime above the Mott point - in striking agreement with all available\nexperiments.",
        "category": "cond-mat"
    },
    {
        "text": "Overcoming correlation fluctuations in two-photon interference\n  experiments with differently bright and independently blinking remote quantum\n  emitters: As a fundamental building block for quantum computation and communication\nprotocols, the correct verification of the two-photon interference (TPI)\ncontrast between two independent quantum light sources is of utmost importance.\nHere, we experimentally demonstrate how frequently present blinking dynamics\nand changes in emitter brightness critically affect the Hong-Ou-Mandel-type\n(HOM) correlation histograms of remote TPI experiments measured via the\ncommonly utilized setup configuration. We further exploit this qualitative and\nquantitative explanation of the observed correlation dynamics to establish an\nalternative interferometer configuration, which is overcoming the discussed\ntemporal fluctuations, giving rise to an error-free determination of the remote\nTPI visibility. We prove full knowledge of the obtained correlation by\nreproducing the measured correlation statistics via Monte-Carlo simulations. As\nexemplary system, we make use of two pairs of remote semiconductor quantum\ndots, however, the same conclusions apply for TPI experiments with flying\nqubits from any kind of remote solid state quantum emitters.",
        "category": "cond-mat"
    },
    {
        "text": "Dissipationless counterflow currents above T_c in bilayer\n  superconductors: We report the existence of dissipationless currents in bilayer\nsuperconductors above the critical temperature $T_c$, assuming that the\nsuperconducting phase transition is dominated by phase fluctuations. Using a\nsemiclassical $U(1)$ lattice gauge theory, we show that thermal fluctuations\ncause a transition from the superconducting state at low temperature to a\nresistive state above $T_c$, accompanied by the proliferation of unbound\nvortices. Remarkably, while the proliferation of vortex excitations causes\ndissipation of homogeneous in-plane currents, we find that counterflow\ncurrents, flowing in opposite direction within a bilayer, remain\ndissipationless. The presence of a dissipationless current channel above $T_c$\nis attributed to the inhibition of vortex motion by local superconducting\ncoherence within a single bilayer, in the presence of counterflow currents. Our\ntheory presents a possible scenario for the pseudogap phase in bilayer\ncuprates.",
        "category": "cond-mat"
    },
    {
        "text": "Scaling Relations for Temperature Dependences of the Surface\n  Self-Diffusion Coefficient in Crystallized Molecular Glasses: Crystallization kinetics has features that are universal and independent of\nthe type of crystallized system. The possibility of using scaling relations to\ndescribe the temperature dependences of the surface self-diffusion coefficient\n$D_s$, which is one of the key characteristics of crystallization kinetics, has\nbeen demonstrated in application to various crystallized molecular glasses. It\nhas been shown that the surface self-diffusion coefficient $D_s$ as a function\nof the dimensionless temperature is reproduced by a power law and is\nuniversally scaled for all considered systems. The analysis of experimental\ndata has revealed a correlation between the crystallization kinetic\ncharacteristics, index of fragility, and criterion of the glass-forming ability\nof a liquid. It has been shown that this correlation can be obtained within the\ngeneralized Einstein-Stokes relation.",
        "category": "cond-mat"
    },
    {
        "text": "Tunneling current characteristics in bilayer quantum Hall systems: Weakly disordered bilayer quantum Hall systems at filling factor $\\nu=1$ show\nspontaneous interlayer phase coherence if the layers are sufficiently close\ntogether. We study the collective modes in the system, the current-voltage\ncharacteristics and their evolution with an in-plane magnetic field in the\nphase-coherent regime.",
        "category": "cond-mat"
    },
    {
        "text": "Dirac states in armchair- and zigzag-edged graphene M\u00f6bius strips: Edge structure plays an essential role in the nature of electronic states in\ngraphene nanoribbons. By focusing on the interplay between this feature and\nnon-trivial topology in the domain of the Dirac confinement problem, this paper\nproposes to examine how effects associated with edge shape manifest themselves\nin conjunction with the topological signature typical of M\\\"{o}bius strips\nwithin a low-energy regime. Aiming to provide an alternative to prevailing\ntight-binding approaches, zigzag and armchair M\\\"{o}bius strips are modeled by\nproposing compatible sets of boundary conditions, prescribing profiles of\nterminations in both transverse and longitudinal directions which are\ndemonstrated to be coherent in describing consistently transverse edge patterns\nin combination with a proper M\\\"{o}bius periodicity. Of particular importance\nis the absence of constraints on the solution, in contrast with infinite mass\nanalogues, as well as an energy spectrum with a characteristic dual structure\nresponding exclusively to the parity associated with the transverse quantum\nnumber. Zigzag ribbons are predicted to possess an intrinsic mechanism for\nparity inversion, while the armchair ones carry the possibility of a coexistent\ngapless and gapped band structure. We also inspect the influence of the edge\nstructure on persistent currents. In zigzag-edged configurations they are found\nto be sensitive to a length-dependent term which behaves as an effective flux.\nArmchair rings show a quite distinctive property: alternation of constant and\nflux-dependent currents according to the width of the ring, for a fixed\ntransverse quantum number. In the flux-free case the effects of topology are\nfound to be entirely suppressed, and conventional odd and even currents become\nundistinguishable.",
        "category": "cond-mat"
    },
    {
        "text": "Lagrange statistics in systems (markets) with price constraints:\n  Analysis of property, car sales, marriage and job markets by the Boltzmann\n  function and the Pareto distribution: Statistical models of economic distributions lead to Boltzmann distributions\nrather than a Pareto power law. This result is supported by two facts: 1. the\ndistributions of income, car sales, marriages or jobs are a matter of chances\nand luck and not of reason! 2. Data for property, automobile sales, marriages\nand job markets were analyzed by two models: the Pareto law and the Boltzmann\ndistribution of stochastic systems. In all cases the best fits to data were\nobtained by the Boltzmann function. This may indicate that the principles of\nstochastic systems like in physics, chemistry, thermodynamics may also be\napplied to economic systems.",
        "category": "cond-mat"
    },
    {
        "text": "A Paradox in the Langevin Equation with Long-Time Noise Correlations: We solve the generalized Langevin equation driven by a stochastic force with\npower-law autocorrelation function. A stationary Markov process has been\napplied as a model of the noise. However, the resulting velocity variance does\nnot stabilizes but diminishes with time. It is shown that algebraic\ndistributions can induce such non-stationary affects. Results are compared to\nthose obtained with a deterministic random force. Consequences for the\ndiffusion process are also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Assessing the potential of perfect screw dislocations in SiC for\n  solid-state quantum technologies: Although point defects in solids are one of the most promising physical\nsystems to build functioning qubits, it remains challenging to position them in\na deterministic array and to integrate them into large networks. By means of\nadvanced ab initio calculations we show that undissociated screw dislocations\nin cubic 3C-SiC, and their associated strain fields, could be used to create a\ndeterministic pattern of relevant point defects. Specifically, we present a\ndetailed analysis of the formation energies and electronic structure of the\ndivacancy in 3C-SiC when located in the vicinity of this type of dislocations.\nOur results show that the divacancy is strongly attracted towards specific and\nequivalent sites inside the core of the screw dislocations, and would form a\none-dimensional arrays along them. Furthermore, we show that the same strain\nthat attracts the divacancy allows the modulation of the position of its\nelectronic states and of its charge transition levels. In the case of the\nneutral divacancy, we find that these modulations result in the loss of its\npotential as a qubit. However, these same modulations could transform defects\nwith no potential as qubits when located in bulk, into promising defects when\nlocated inside the core of the screw dislocations. Since dislocations are still\nmostly perceived as harmful defects, our findings represent a technological\nleap as they show that dislocations can be used as active building blocks in\nfuture defect-based quantum computers.",
        "category": "cond-mat"
    },
    {
        "text": "The effect of layer number and substrate on the stability of graphene\n  under MeV proton beam irradiation: The use of graphene electronics in space will depend on the radiation\nhardness of graphene. The damage threshold of graphene samples, subjected to 2\nMeV proton irradiation, was found to increase with layer number and also when\nthe graphene layer was supported by a substrate. The thermal properties of\ngraphene as a function of the number of layers or as influenced by the\nsubstrate argue against a thermal model for the production of damage by the ion\nbeam. We propose a model of intense electronically-stimulated surface\ndesorption of the atoms as the most likely process for this damage mechanism.",
        "category": "cond-mat"
    },
    {
        "text": "Ferrodistortive instability at the (001) surface of half-metallic\n  manganites: We present the structure of the fully relaxed (001) surface of the\nhalf-metallic manganite La0.7Sr0.3MnO3, calculated using density functional\ntheory within the generalized gradient approximation (GGA). Two relevant\nferroelastic order parameters are identified and characterized: The tilting of\nthe oxygen octahedra, which is present in the bulk phase, oscillates and\ndecreases towards the surface, and an additional ferrodistortive Mn\noff-centering, triggered by the surface, decays monotonically into the bulk.\nThe narrow d-like energy band that is characteristic of unrelaxed manganite\nsurfaces is shifted down in energy by these structural distortions, retaining\nits uppermost layer localization. The magnitude of the zero-temperature\nmagnetization is unchanged from its bulk value, but the effective spin-spin\ninteractions are reduced at the surface.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamics of Successive Minor Hysteresis Loops: Cumulative growth of successive minor hysteresis loops in Co/Pd multilayers\nwith perpendicular anisotropy was studied in the context of time dependent\nmagnetization reversal dynamics. We show that in disordered ferromagnets, where\nmagnetization reversal involves nucleation, domains' expansion and\nannihilation, differences between the time dependencies of these processes are\nresponsible for accumulation of nuclei for rapid domain expansion, for the\nasymmetry of forward and backward magnetization reversals and for the\nrespective cumulative growth of hysteresis loops. Loops stop changing and\nbecome macroscopically reproducible when populations of upward and downward\nnucleation domains balance each other and the respective upward and downward\nreversal times stabilize.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of Weyl nodes in TaAs: In 1929, H. Weyl proposed that the massless solution of Dirac equation\nrepresents a pair of new type particles, the so-called Weyl fermions [1].\nHowever the existence of them in particle physics remains elusive for more than\neight decades. Recently, significant advances in both topological insulators\nand topological semimetals have provided an alternative way to realize Weyl\nfermions in condensed matter as an emergent phenomenon: when two non-degenerate\nbands in the three-dimensional momentum space cross in the vicinity of Fermi\nenergy (called as Weyl nodes), the low energy excitation behaves exactly the\nsame as Weyl fermions. Here, by performing soft x-ray angle-resolved\nphotoemission spectroscopy measurements which mainly probe bulk band structure,\nwe directly observe the long-sought-after Weyl nodes for the first time in\nTaAs, whose projected locations on the (001) surface match well to the Fermi\narcs, providing undisputable experimental evidence of existence of Weyl fermion\nquasiparticles in TaAs.",
        "category": "cond-mat"
    },
    {
        "text": "Acoustic interactions between inversion symmetric and asymmetric\n  two-level systems: Amorphous solids, as well as many disordered lattices, display remarkable\nuniversality in their low temperature acoustic properties. This universality is\nattributed to the attenuation of phonons by tunneling two-level systems (TLSs),\nfacilitated by the interaction of the TLSs with the phonon field. TLS-phonon\ninteraction also mediates effective TLS-TLS interactions, which dictates the\nexistence of a glassy phase and its low energy properties. Here we consider\nKBr:CN, the archetypal disordered lattice showing universality. We calculate\nnumerically, using conjugate gradients method, the effective TLS-TLS\ninteractions for inversion symmetric (CN flips) and asymmetric (CN rotations)\nTLSs, in the absence and presence of disorder, in two and three dimensions. The\nobserved dependence of the magnitude and spatial power law of the interaction\non TLS symmetry, and its change with disorder, characterizes TLS-TLS\ninteractions in disordered lattices in both extreme and moderate dilutions. Our\nresults are in good agreement with the two-TLS model, recently introduced to\nexplain long-standing questions regarding the quantitative universality of\nphonon attenuation and the energy scale of $\\approx 1-3$ K below which\nuniversality is observed.",
        "category": "cond-mat"
    },
    {
        "text": "Stable diagonal stripes in the t-J model at $\\bar{n}_h$=1/8 doping from\n  fPEPS calculations: We investigate the 2D t-J model at a hole doping of $\\bar{n}_h$=1/8 using\nrecently developed high accuracy fermionic projected entangled pair\nstates(fPEPS) method. By applying stochastic gradient descent method combined\nwith Monte Carlo sampling technique, we obtain the ground state hole energy\n$E_{\\rm hole}$=-1.6186 for $J/t$=0.4. We show that the ground state has stable\ndiagonal stripes instead of vertical stripes with width of 4 unit cells, and\nstripe filling $\\rho_l$=0.5. We further show that the long range\nsuperconductivity order is suppressed at this point.",
        "category": "cond-mat"
    },
    {
        "text": "Phase change materials for nano-polaritonics: a case study of hBN/VO2\n  heterostructures: Polaritonic excitation and control in van der Waals (vdW) materials exhibit\nsuperior merits than conventional materials and thus hold new promise for\nexploring light matter interactions. In this work, we created vdW\nheterostructures combining hexagonal boron nitride (hBN) and a representative\nphase change material - vanadium dioxide (VO2). Using infrared\nnano-spectroscopy and nano-imaging, we demonstrated the dynamic tunability of\nhyperbolic phonon polaritons in hBN/VO2 heterostructures by temperature control\nin a precise and reversible fashion. The dynamic tuning of the polaritons stems\nfrom the change of local dielectric properties of the VO2 sublayer through\ninsulator to metal transition by the temperature control. The high\nsusceptibility of polaritons to electronic phase transitions opens\npossibilities for applications of vdW materials in combination with correlated\nphase change materials.",
        "category": "cond-mat"
    },
    {
        "text": "Detecting sign-changing superconducting gap in LiFeAs using\n  quasiparticle interference: Using a realistic ten-orbital tight-binding model Hamiltonian fitted to the\nangle-resolved photoemission (ARPES) data on LiFeAs, we analyze the\ntemperature, frequency, and momentum dependencies of quasiparticle interference\n(QPI) to identify gap sign changes in a qualitative way, following our original\nproposal [Phys. Rev. B 92, 184513 (2015)]. We show that all features present\nfor the simple two-band model for the sign-changing $s_{+-}$-wave\nsuperconducting gap employed previously are still present in the realistic\ntight-binding approximation and gap values observed experimentally. We discuss\nvarious superconducting gap structures proposed for LiFeAs, and identify\nvarious features of these superconducting gaps functions in the quasiparticle\ninterference patterns. On the other hand, we show that it will be difficult to\nidentify the more complicated possible sign structures of the hole pocket gaps\nin LiFeAs, due to the smallness of the pockets and the near proximity of two of\nthe gap energies.",
        "category": "cond-mat"
    },
    {
        "text": "Dissipationless Anomalous Hall Current in $Fe_{100-x}(SiO_2)_x$ Films: The observation of dissipationless anomalous Hall current is one of the\nexperimental evidences to confirm the intrinsic origin of anomalous Hall\neffect. To study the origin of anomalous Hall effect in iron,\nFe$_{100-x}$(SiO$_{2}$)$_{x}$ granular films with volume fraction of SiO$_{2}$\n0\\le x \\le 40.51 were fabricated using co-sputtering. Hall and longitudinal\nresistivities were measured in the temperature range 5 to 350 K with magnetic\nfields up to 5 Tesla. As x increased from 0 to 40.51, the anomalous Hall\nresistivity and longitudinal resistivity increased about 4 and 3 orders in\nmagnitude, respectively. Analysis of the results revealed that the normalized\nanomalous Hall conductivity is a constant for all the samples, the evidence of\ndissipationless anomalous Hall current in Fe.",
        "category": "cond-mat"
    },
    {
        "text": "Steady state extensional rheology of a dilute suspension of spheres in a\n  dilute polymer solution: We investigate the steady-state extensional rheology of a dilute suspension\nof spherical particles in a dilute polymer solution. For a particle-free\npolymeric fluid, in addition to the solvent viscosity, the extensional\nviscosity due to the polymers, $\\mu^\\text{poly}$, contributes to the total\nnon-dimensionalized extensional viscosity $1+\\mu^\\text{poly}$. When a small\nvolume fraction, $\\phi$, of spheres is added to a polymeric fluid, the stress\nis altered by the Einstein viscosity of 2.5$\\phi$ and two additional stress\ncontributions: the interaction stresslet and the particle-induced polymer\nstress (PIPS). The net interaction stress is positive at lower Deborah numbers\n(product of extension rate and polymer relaxation time), $De\\lesssim0.5$, and\nnegative at large $De$. Relative to undisturbed flow, the presence of spheres\nin uniaxial extensional flow creates larger and smaller local stretching\nregions. Below the coil-stretch transition ($De<0.5$), the polymers far from\nthe particles are in a coiled state, and a wake of stretched polymers forms\ndownstream of the particle as they are stretched by the large stretching\nregions around the particle. This leads to a positive interaction stresslet\n(surface) and the PIPS (stretched wake). Beyond the coil-stretch transition,\npolymers far from the particle are highly stretched, but they collapse closer\nto the coiled state as they arrive at the low-stretching regions near the\nparticle surface. Therefore, a negative PIPS results from the regions of\ncollapsed polymers. When $De\\gtrsim0.6$, the changes in extensional viscosity\nfrom the interaction stresslet and the PIPS are $\\phi\\mu^\\text{poly}$ and\napproximately -1.85$\\phi\\mu^\\text{poly}$, respectively. At large $De$, the\npolymer extensional viscosity, $\\mu^\\text{poly}$, is large. Therefore, adding\nparticles reduces the extensional viscosity of the suspension\n($(2.5-0.85\\mu^\\text{poly})\\phi<0$).",
        "category": "cond-mat"
    },
    {
        "text": "Instabilities of a Filled Vortex in a Two-Component Bose-Einstein\n  Condensate: A two-component Bose-Einstein condensate of cold atoms with a strong\nintercomponent repulsion leading to the spatial separation of the components\nhas been numerically studied. Configurations with a multiple quantized vortex\nin one component, where the vortex core is filled with the other component, are\nconsidered. The effective radius of the core can exceed the width of the\ntransition layer between components, and then an analogy with a filled\ncylindrical vortex in the classical hydrodynamics of two immiscible ideal\nfluids appears. This analogy allows one to analyze the longitudinal \"sausage\"\ninstability and the transverse instability of the filled vortex in the\ncondensate caused by the \"tangential discontinuity,\" as well as the stable\nregime in the parametric gap between them. The presence of long-lived coherent\nstructures formed in some cases at the nonlinear stages of both instabilities\nis numerically discovered.",
        "category": "cond-mat"
    },
    {
        "text": "Voltage Control of Exchange Coupling in Phosphorus Doped Silicon: Motivated by applications to quantum computer architectures we study the\nchange in the exchange interaction between neighbouring phosphorus donor\nelectrons in silicon due to the application of voltage biases to surface\ncontrol electrodes. These voltage biases create electro-static fields within\nthe crystal substrate, perturbing the states of the donor electrons and thus\naltering the strength of the exchange interaction between them. We find that\ncontrol gates of this kind can be used to either enhance, or reduce the\nstrength of the interaction, by an amount that depends both on the magnitude\nand orientation of the donor separation.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical slowing down in an ultrafast photo-induced phase transition: Complex systems, which consist of a large number of interacting constituents,\noften exhibit universal behavior near a phase transition. A slowdown of certain\ndynamical observables is one such recurring feature found in a vast array of\ncontexts. This phenomenon, known as critical slowing down, is well studied\nmostly in thermodynamic phase transitions. However, it is less understood in\nhighly nonequilibrium settings, where the time it takes to traverse the phase\nboundary becomes comparable to the timescale of dynamical fluctuations. Using\ntransient optical spectroscopy and femtosecond electron diffraction, we studied\na photo-induced transition of a model charge-density-wave (CDW) compound,\nLaTe$_3$. We observed that it takes the longest time to suppress the order\nparameter at the threshold photoexcitation density, where the CDW transiently\nvanishes. This finding can be quantitatively captured by generalizing the\ntime-dependent Landau theory to a system far from equilibrium. The experimental\nobservation and theoretical understanding of dynamical slowing down may offer\ninsight into other general principles behind nonequilibrium phase transitions\nin many-body systems.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum Mechanics with a Momentum-Space Artificial Magnetic Field: The Berry curvature is a geometrical property of an energy band which acts as\na momentum space magnetic field in the effective Hamiltonian describing\nsingle-particle quantum dynamics. We show how this perspective may be exploited\nto study systems directly relevant to ultracold gases and photonics. Given the\nexchanged roles of momentum and position, we demonstrate that the global\ntopology of momentum space is crucially important. We propose an experiment to\nstudy the Harper-Hofstadter Hamiltonian with a harmonic trap that will\nillustrate the advantages of this approach and that will also constitute the\nfirst realization of magnetism on a torus.",
        "category": "cond-mat"
    },
    {
        "text": "Optical properties of an effective one-band Hubbard model for the\n  cuprates: We study the Cu and O spectral density of states and the optical conductivity\nof CuO_2 planes using an effective generalized one-band Hubbard model derived\nfrom the extended three-band Hubbard model. We solve exactly a square cluster\nof 10 unit cells and average the results over all possible boundary conditions,\nwhat leads to smooth functions of frequency. Upon doping, the Fermi energy\njumps to Zhang-Rice states which are connected to the rest of the valence band\n(in contrast to an isolated new band in the middle of the gap). The transfer of\nspectral weight depends on the parameters of the original three-band model not\nonly through the one-band effective parameters but also through the relevant\nmatrix elements. We discuss the evolution of the gap upon doping. The optical\nconductivity of the doped system shows a mid-infrared peak due to intraband\ntransitions, a pseudogap and a high frequency part related to interband\ntransitions. Its shape and integrated weight up to a given frequency (including\nthe Drude weight) agree qualitatively with experiments in the cuprates for low\nto moderate doping levels, but significant deviations exist for doping $x>0.3$.",
        "category": "cond-mat"
    },
    {
        "text": "Bose-Einstein Condensation and quasicrystals: We consider interacting Bose particles in an external local potential. It is\nshown that large class of external quasicrystal potentials cannot sustain any\ntype of Bose-Einstein condensates. Accordingly, at spatial dimensions $D\\leq 2$\nin such quasicrystal potentials a supersolid is not possible via Bose-Einstein\ncondensates at finite temperatures. The latter also hold true for the\ntwo-dimensional Fibonacci tiling. However, supersolids do arise at $D\\leq 2$\nvia Bose-Einstein condensates from infinitely long-range, nonlocal\ninterparticle potentials.",
        "category": "cond-mat"
    },
    {
        "text": "Optical properties of $MgCNi_3$ in the normal state: We present the optical reflectance and conductivity spectra for non-oxide\nantiperovskite superconductor $MgCNi_{3}$ at different temperatures. The\nreflectance drops gradually over a large energy scale up to 33,000 cm$^{-1}$,\nwith the presence of several wiggles. The reflectance has slight temperature\ndependence at low frequency but becomes temperature independent at high\nfrequency. The optical conductivity shows a Drude response at low frequencies\nand four broad absorption features in the frequency range from 600 $cm^{-1}$ to\n33,000 $cm^{-1}$. We illustrate that those features can be well understood from\nthe intra- and interband transitions between different components of Ni 3d\nbands which are hybridized with C 2p bands. There is a good agreement between\nour experimental data and the first-principle band structure calculations.",
        "category": "cond-mat"
    },
    {
        "text": "Competition between the structural phase transition and\n  superconductivity in Ir$_{1-x}$Pt$_x$Te$_2$ as revealed by pressure effects: Pressure-dependent transport measurements of Ir$_{1-x}$Pt$_x$Te$_2$ are\nreported. With increasing pressure, the structural phase transition at high\ntemperatures is enhanced while its superconducting transition at low\ntemperatures is suppressed. These pressure effects make Ir$_{1-x}$Pt$_x$Te$_2$\ndistinct from other studied $T$X$_2$ systems exhibiting a charge density wave\n(CDW) state, in which pressure usually suppresses the CDW state and enhances\nthe superconducting state. The results reveal that the emergence of\nsuperconductivity competes with the stabilization of the low temperature\nmonoclinic phase in Ir$_{1-x}$Pt$_x$Te$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Topological flat bands in a kagom\u00e9 lattice multiorbital system: Flat bands and dispersive Dirac bands are known to coexist in the electronic\nbands in a two-dimensional kagome lattice. Including the relativistic\nspin-orbit coupling, such systems often exhibit nontrivial band topology,\nallowing for gapless edge modes between flat bands at several locations in the\nband structure, and dispersive bands or at the Dirac band crossing. Here, we\ntheoretically demonstrate that a multiorbital system on a kagome lattice is a\nversatile platform to explore the interplay between nontrivial band topology\nand electronic interaction. Specifically, here we report that the multiorbital\nkagome model with the atomic spin-orbit coupling naturally supports topological\nbands characterized by nonzero Chern numbers $\\cal C$, including a flat band\nwith $|{\\cal C}| =1$. When such a flat band is $1/3$ filled, the non-local\nrepulsive interactions induce a fractional Chern insulating state. We also\ndiscuss the possible realization of our findings in real kagome materials.",
        "category": "cond-mat"
    },
    {
        "text": "Nearest level spacing statistics in open chaotic systems: a\n  generalization of the Wigner Surmise: We investigate the nearest level spacing statistics of open chaotic wave\nsystems. To this end we derive the spacing distributions for the three Wigner\nensembles in the one-channel case. The theoretical results give a clear\nphysical meaning of the modifications on the spacing distributions produced by\nthe coupling to the environment. Based on the analytical expressions obtained,\nwe then propose general expressions of the spacing distributions for any number\nof channels, valid from weak to strong coupling. The latter expressions contain\none free parameter. The surmise is successfully compared with numerical\nsimulations of non-Hermitian random matrices and with experimental data\nobtained with a lossy electromagnetic chaotic cavity.",
        "category": "cond-mat"
    },
    {
        "text": "Theoretical Understanding of Photon Spectroscopies in Correlated\n  Materials In and Out of Equilibrium: Photon-based spectroscopies have had a significant impact on both fundamental\nscience and applications by providing an efficient approach to investigate the\nmicroscopic physics of materials. Together with the development of synchrotron\nX-ray techniques, theoretical understanding of the spectroscopies themselves\nand the underlying physics that they reveal has progressed through advances in\nnumerical methods and scientific computing. In this review, we provide an\noverview of theories for angle-resolved photoemission spectroscopy and resonant\ninelastic X-ray scattering applied to quantum materials. First, we discuss\nmethods for studying equilibrium spectroscopies, including first-principles\napproaches, numerical many-body methods and a few analytical advances. Second,\nwe assess the recent development of ultrafast techniques for out-of-equilibrium\nspectroscopies, from characterizing equilibrium properties to generating\ntransient or metastable states, mainly from a theoretical point of view.\nFinally, we identify the main challenges and provide an outlook for the future\ndirection of the field.",
        "category": "cond-mat"
    },
    {
        "text": "Chaos-assisted tunneling resonances in a synthetic Floquet superlattice: The field of quantum simulation, which aims at using a tunable quantum system\nto simulate another, has been developing fast in the past years as an\nalternative to the all-purpose quantum computer. In particular, the use of\ntemporal driving has attracted a huge interest recently as it was shown that\ncertain fast drivings can create new topological effects, while a strong\ndriving leads to e.g. Anderson localization physics. In this work, we focus on\nthe intermediate regime to observe a quantum chaos transport mechanism called\nchaos-assisted tunneling which provides new possibilities of control for\nquantum simulation. Indeed, this regime generates a rich classical phase space\nwhere stable trajectories form islands surrounded by a large sea of unstable\nchaotic orbits. This mimics an effective superlattice for the quantum states\nlocalized in the regular islands, with new controllable tunneling properties.\nBesides the standard textbook tunneling through a potential barrier,\nchaos-assisted tunneling corresponds to a much richer tunneling process where\nthe coupling between quantum states located in neighboring regular islands is\nmediated by other states spread over the chaotic sea. This process induces\nsharp resonances where the tunneling rate varies by orders of magnitude over a\nshort range of parameters. We experimentally demonstrate and characterize these\nresonances for the first time in a quantum system. This opens the way to new\nkinds of quantum simulations with long-range transport and new types of control\nof quantum systems through complexity.",
        "category": "cond-mat"
    },
    {
        "text": "Spacial Modulation of the Magnetization in Cobalt Nanowires: Cobalt nanowires with a diameter in the range between 50 to 100nm can be\nprepared as single-crystal wires with the easy axis (the c-axis) perpendicular\nto the wire axis. The competition between the crystal anisotropy and\ndemagnetization energy frustrates the magnetization direction. A periodic\nmodulation of the angle between M and the wire axis yields a lower energy.",
        "category": "cond-mat"
    },
    {
        "text": "Learning hidden elasticity with deep neural networks: We introduce a de novo elastography method to learn the elasticity of solids\nfrom measured strains. The deep neural network in our new method is supervised\nby the theory of elasticity and does not require labeled data for training.\nResults show that the proposed method can learn the hidden elasticity of solids\naccurately and is robust when it comes to noisy and missing measurements. A\nprobable elasticity distribution for areas without measurements may also be\nreconstructed by the neural network based on the elasticity distribution in\nnearby regions. The neural network learns the hidden elasticity of solids as a\nfunction of positions and thus it can generate elasticity images with an\narbitrary resolution. This feature is applied to create super-resolution\nelasticity images in this study. We demonstrate that the neural network can\nalso learn the hidden physics when strain and elasticity distributions are both\ngiven. The proposed method has various unique features and can be applied to a\nbroad range of elastography applications.",
        "category": "cond-mat"
    },
    {
        "text": "Mott Insulator to Superfluid Phase Transition in Bravais Lattices via\n  the Jaynes-Cummings-Hubbard Model: The Properties of the Mott insulator to superfluid phase transition are\nobtained through the fermionic approximation in the Jaynes-Cummings-Hubbard\nmodel on linear, square, SC, FCC, and BCC Bravais lattices. For varying\nexcitation number and atom-cavity frequency detuning. We find that the Mott\nlobes and the critical hopping are not scalable only for the FCC lattice. At\nthe large excitation number regime, the critical hopping is scalable for all\nthe lattices and it does not depend on the detuning.",
        "category": "cond-mat"
    },
    {
        "text": "Spin Hall Effect in a Thin Pt Film: A density-functional-theory based relativistic scattering formalism is used\nto study charge transport through thin Pt films with room temperature lattice\ndisorder. A Fuchs-Sondheimer specularity coefficient $p \\sim 0.5$ is needed to\ndescribe the suppression of the charge current at the surface even in the\nabsence of surface roughness. The charge current drives a spin Hall current\nperpendicular to the surface. Analysing the latter with a model that is\nuniversally used to interpret the spin Hall effect in thin films and layered\nmaterials, we are unable to recover values of the spin-flip diffusion length\n$l_{\\rm sf}$ and spin Hall angle $\\Theta_{\\rm sH}$ that we obtain for bulk Pt\nusing the same approximations. We trace this to the boundary conditions used\nand develop a generalized model that takes surface effects into account. A\nreduced value of $\\Theta_{\\rm sH}$ at the surface is then found to describe the\nfirst-principles transport results extremely well. The in-plane spin Hall\neffect is substantially enhanced at the surface.",
        "category": "cond-mat"
    },
    {
        "text": "Density fluctuations of polymers in disordered media: We study self avoiding random walks in an environment where sites are\nexcluded randomly, in two and three dimensions. For a single polymer chain, we\nstudy the statistics of the time averaged monomer density and show that these\nare well described by multifractal statistics. This is true even far from the\npercolation transition of the disordered medium. We investigate solutions of\nchains in a disordered environment and show that the statistics cease to be\nmultifractal beyond the screening length of the solution.",
        "category": "cond-mat"
    },
    {
        "text": "Orbital structure and magnetic ordering in stoichiometric and doped\n  crednerite CuMnO2: The exchange interactions and magnetic structure in layered system CuMnO2\n(mineral crednerite) and in nonstoichiometric system Cu1.04Mn0.96O2, with\ntriangular layers distorted due to orbital ordering of the Mn3+ ions, are\nstudied by ab-initio band-structure calculations, which were performed within\nthe GGA+U approximation. The exchange interaction parameters for the Heisenberg\nmodel within the Mn-planes and between the Mn-planes were estimated. We explain\nthe observed in-plane magnetic structure by the dominant mechanism of the\ndirect d-d exchange between neighboring Mn ions. The superexchange via O ions,\nwith 90 degree Mn-O-Mn bonds, plays less important role for the in-plane\nexchange. The interlayer coupling is largely dominated by one exchange path\nbetween the half-filled 3z^2-r^2 orbitals of Mn3+. The change of interlayer\ncoupling from antiferromagnetic in pure CuMnO2 to ferromagnetic in doped\nmaterial is also explained by our calculations.",
        "category": "cond-mat"
    },
    {
        "text": "Theory of Electronic Ferroelectricity: We present a theory of the linear and nonlinear optical characteristics of\nthe insulating phase of the Falicov-Kimball model within the self-consistent\nmean-field approximation. The Coulomb attraction between the itinerant\nd-electrons and the localized f-holes gives rise to a built-in coherence\nbetween the d and f-states, which breaks the inversion symmetry of the\nunderlying crystal, leading to: (1) electronic ferroelectricity, (2)\nferroelectric resonance, and (3) a nonvanishing susceptibility for\nsecond-harmonic generation. As experimental tests of such a built-in coherence\nin mixed-valent compounds we propose measurements of the static dielectric\nconstant, the microwave absorption spectrum, and the dynamic second-order\nsusceptibility.",
        "category": "cond-mat"
    },
    {
        "text": "Kohn-Sham computation and the bivariate view of density functional\n  theory: Informed by an abstraction of Kohn-Sham computation called a KS machine, a\nfunctional analytic perspective is developed on mathematical aspects of density\nfunctional theory. A natural semantics for the machine is bivariate, consisting\nof a sequence of potentials paired with a ground density. Although the question\nof when the KS machine can converge to a solution (where the potential\ncomponent matches a designated target) is not resolved here, a number of\nrelated ones are. For instance: Can the machine progress toward a solution?\nBarring presumably exceptional circumstances, yes in an energetic sense, but\nusing a potential-mixing scheme rather than the usual density-mixing variety.\nAre energetic and function space distance notions of proximity-to-solution\ncommensurate? Yes, to a significant degree. If the potential components of a\nsequence of ground pairs converges to a target density, do the density\ncomponents cluster on ground densities thereof? Yes, barring particle number\ndrifting to infinity.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-triplet Superconductivity in Nonsymmorphic crystals: Spin-triplet superconductivity is known to be a rare quantum phenomenon. Here\nwe show that nonsymmorphic crystalline symmetries can dramatically assist\nspin-triplet superconductivity in the presence of spin-orbit coupling. Even\nwith a weak spin-orbit coupling, the spin-triplet pairing can be the leading\npairing instability in a lattice with a nonsymmorphic symmetry. The underlining\nmechanism is the spin-sublattice-momentum lock on electronic bands that are\nprotected by the nonsymmorphic symmetry. We use the nonsymmorphic space group\nP4/nmm to demonstrate these results and discuss related experimental\nobservables. Our work paves a new way in searching for spin-triplet\nsuperconductivity.",
        "category": "cond-mat"
    },
    {
        "text": "Shot noise and tunnel magnetoresistance in multilevel quantum dots:\n  Effects of cotunneling: Spin-dependent transport through a multilevel quantum dot weakly coupled to\nferromagnetic leads is analyzed theoretically by means of the real-time\ndiagrammatic technique. Both the sequential and cotunneling processes are taken\ninto account, which makes the results on tunnel magnetoresistance (TMR) and\nshot noise applicable in the whole range of relevant bias and gate voltages.\nSuppression of the TMR due to inelastic cotunneling and super-Poissonian shot\nnoise have been found in some of the Coulomb blockade regions. Furthermore, in\nthe Coulomb blockade regime there is an additional contribution to the noise\ndue to bunching of cotunneling processes involving the spin-majority electrons.\nOn the other hand, in the sequential tunneling regime TMR oscillates with the\nbias voltage, while the current noise is generally sub-Poissonian.",
        "category": "cond-mat"
    },
    {
        "text": "A microstructural analysis of 2D halide perovskites: Stability and\n  functionality: Recent observations indicated that the photoelectric conversion properties of\nperovskite materials are intimately related to the presence of superlattice\nstructures and other unusual nanoscale features in them. The low dimensional or\nmixed dimensional halide perovskite family are found to be more efficient\nmaterials for device application compared to 3-dimensional halide perovskites.\nThe emergence of perovskite solar cell has revolutionized the solar cell\nindustry because of their flexible architecture and rapidly increased\nefficiency. Tuning the dielectric constant, charge separation are the main\nobjective in designing a photovoltaic device that can be explored using\n2-dimensional perovskite family. Thus, revisiting the fundamental properties of\nperovskite crystals could reveal further possibilities for recognizing these\nimprovements towards device functionality. In this context, this review\ndiscusses the material properties of 2-dimensional halide perovskite and\nrelated optoelectronic devices aiming particularly for solar cell application.",
        "category": "cond-mat"
    },
    {
        "text": "Maximum entropy analytic continuation for frequency-dependent transport\n  coefficients with non-positive spectral weight: The computation of transport coefficients, even in linear response, is a\nmajor challenge for theoretical methods that rely on analytic continuation of\ncorrelations functions obtained numerically in Matsubara space. While maximum\nentropy methods can be used for certain correlation functions, this is not\npossible in general, important examples being the Seebeck, Hall, Nernst and\nReggi-Leduc coefficients. Indeed, positivity of the spectral weight on the\npositive real-frequency axis is not guaranteed in these cases. The spectral\nweight can even be complex in the presence of broken time-reversal symmetry.\nVarious workarounds, such as the neglect of vertex corrections or the study of\nthe infinite frequency or Kelvin limits have been proposed. Here, we show that\none can define auxiliary response functions that allow to extract the desired\nreal-frequency susceptibilities from maximum entropy methods in the most\ngeneral multiorbital cases with no particular symmetry. As a benchmark case, we\nstudy the longitudinal thermoelectric response and corresponding Onsager\ncoefficient in the single-band two-dimensional Hubbard model treated with\ndynamical mean-field theory (DMFT) and continuous-time quantum Monte Carlo\n(CTQMC). We thereby extend to transport coefficients the maximum entropy\nanalytic continuation with auxiliary functions (MaxEntAux method), developed\nfor the study of the superconducting pairing dynamics of correlated materials.",
        "category": "cond-mat"
    },
    {
        "text": "Boson pairing and unusual criticality in a generalized XY model: We discuss the unusual critical behavior of a generalized XY model containing\nboth 2\\pi-periodic and \\pi-periodic couplings between sites. The presence of\nvortices and half-vortices allows for single-particle condensate and\npair-condensate phases. Using a field theoretic formulation and worm algorithm\nMonte Carlo simulations, we show that in two dimensions it is possible for the\nsystem to pass directly from the disordered (high temperature) phase to the\nsingle particle (quasi)-condensate via an Ising transition, a situation\nreminiscent of the `deconfined criticality' scenario.",
        "category": "cond-mat"
    },
    {
        "text": "Real-time measurement of laser induced photoconductivity in sol-gel\n  derived Al doped ZnO thin films: In this paper Al doped ZnO (AZO) thin films with 0, 3, 6 and 12 at. % Al\nconcentration were prepared by sol-gel method on glass substrates. The\ndeposited films were annealed at different temperatures of 300, 350, 400, 450\nand 500 {\\deg}C for 1 h in air. X-ray diffraction (XRD) showed wurtzite\ncrystalline structure for the films annealed above 400 {\\deg}C. The films were\nsubsequently irradiated by beams of excimer (KrF, {\\lambda}=248 nm) laser. The\nevolution of crystal structure, surface morphology and optical properties were\nstudied using XRD, filed emission scanning electron microscope (FE-SEM) and\nUV-Vis spectrophotometer, respectively. Real-time measurement of electrical\nconductivity during laser irradiation showed a transient or persistent\nphotoconductivity effect. The effect of laser energy on this photoconductivity\nwas also investigated. Based on the observed photoluminescence (PL) and X-ray\nphotoelectron spectroscopy (XPS), the observed photoconductivity effect was\ndescribed.",
        "category": "cond-mat"
    },
    {
        "text": "Quotient symmetry protected topological phenomena: Topological phenomena are commonly studied in phases of matter which are\nseparated from a trivial phase by an unavoidable quantum phase transition. This\ncan be overly restrictive, leaving out scenarios of practical relevance --\nsimilar to the distinction between liquid water and vapor. Indeed, we show that\ntopological phenomena can be stable over a large part of parameter space even\nwhen the bulk is strictly speaking in a trivial phase of matter. In particular,\nwe focus on symmetry-protected topological phases which can be trivialized by\nextending the symmetry group. The topological Haldane phase in spin chains\nserves as a paradigmatic example where the $SO(3)$ symmetry is extended to\n$SU(2)$ by tuning away from the Mott limit. Although the Haldane phase is then\nadiabatically connected to a product state, we show that characteristic\nphenomena -- edge modes, entanglement degeneracies and bulk phase transitions\n-- remain parametrically stable. This stability is due to a separation of\nenergy scales, characterized by quantized invariants which are well-defined\nwhen a subgroup of the symmetry only acts on high-energy degrees of freedom.\nThe low-energy symmetry group is a quotient group whose emergent anomalies\nstabilize edge modes and unnecessary criticality, which can occur in any\ndimension.",
        "category": "cond-mat"
    },
    {
        "text": "Topological charge distributions of an interacting two-spin system: Quantum systems are often described by parameter-dependent Hamiltonians.\nPoints in parameter space where two levels are degenerate can carry a\ntopological charge. Here we theoretically study an interacting two-spin system\nwhere the degeneracy points form a nodal loop or a nodal surface in the\nmagnetic parameter space, similarly to such structures discovered in the band\nstructure of topological semimetals. We determine the topological charge\ndistribution along these degeneracy geometries. We show that these\nnon-point-like degeneracy patterns can be obtained not only by fine-tuning, but\nthey can be stabilized by spatial symmetries. Since simple spin systems such as\nthe one studied here are ubiquitous in condensed-matter setups, we expect that\nour findings, and the physical consequences of these nontrivial degeneracy\ngeometries, are testable in experiments with quantum dots, molecular magnets,\nand adatoms on metallic surfaces.",
        "category": "cond-mat"
    },
    {
        "text": "Power-law temporal auto-correlations in day-long records of human\n  physical activity and their alteration with disease: We investigate long-duration time series of human physical activity under\nthree different conditions: healthy individuals in (i) a constant routine\nprotocol and (ii) in regular daily routine, and (iii) individuals diagnosed\nwith multiple chemical sensitivities. We find that in all cases human physical\nactivity displays power law decaying temporal auto-correlations. Moreover, we\nfind that under regular daily routine, time correlations of physical activity\nare significantly different during diurnal and nocturnal periods but that no\ndifference exists under constant routine conditions. Finally, we find\nsignificantly different auto-correlations for diurnal records of patients with\nmultiple chemical sensitivities.",
        "category": "cond-mat"
    },
    {
        "text": "Pseudogap transition within the superconducting phase in the three-band\n  Hubbard model: The onset of the pseudogap in high-$T_c$ superconducting cuprates (HTSC) is\nmarked by the $T^*$ line in the doping-temperature phase diagram, which ends at\na point $p^*$ at zero temperature within the superconducting dome. Although\nvarious theoretical and experimental studies indicate a competition between the\npseudogap and superconductivity, there is no general consensus on the effects\nof the pseudogap within the superconducting phase. We use cluster dynamical\nmean field theory on a three-band Hubbard model for the HTSC to study the\nsuperconducting phase at $T=0$, obtained when doping the charge-transfer\ninsulator, for several values of $U$. We observe a first-order transition\nwithin the superconducting phase, which separates the underdoped and overdoped\nsolutions. The transition to the underdoped solution is marked by a\ndiscontinuous increase in the spectral gap, and on further underdoping the\nspectral gap increases while the superconducting order parameter decreases. We\nconclude that this is due to the onset of the pseudogap in the underdoped\nregion, which contributes to the increasing spectral gap; this is further\nconsistent with the appearance of a pole in the normal component of the\nself-energy, in the antinodal region, in the underdoped solution. This is\naccompanied by a change in the source of the condensation energy from potential\nenergy, in the overdoped region, to kinetic energy in the underdoped region.\nFurther, we also observe that the $d$-wave node vanishes smoothly within the\nsuperconducting phase at low values of hole doping, within the underdoped\nregion. We see this as a manifestation of Mott physics operating at very low\ndoping. Various aspects of the results and their implications are discussed.",
        "category": "cond-mat"
    },
    {
        "text": "High-energy long-lived resonance of electrons in fractal-like\n  semiconductor heterostructures: A fractal-like alignment of quantum wells is shown to accommodate resonant\nstates with long lifetimes. For the parameters of the semiconductor\nheterostructure GaAs/Al$_{0.4}$Ga$_{0.6}$As with the well depth 300meV, a\nresonant state of the energy as high as 44meV with the lifetime as long as\n2.8\\{mu}s is shown to be achievable.",
        "category": "cond-mat"
    },
    {
        "text": "Power laws, Pareto distributions and Zipf's law: When the probability of measuring a particular value of some quantity varies\ninversely as a power of that value, the quantity is said to follow a power law,\nalso known variously as Zipf's law or the Pareto distribution. Power laws\nappear widely in physics, biology, earth and planetary sciences, economics and\nfinance, computer science, demography and the social sciences. For instance,\nthe distributions of the sizes of cities, earthquakes, solar flares, moon\ncraters, wars and people's personal fortunes all appear to follow power laws.\nThe origin of power-law behaviour has been a topic of debate in the scientific\ncommunity for more than a century. Here we review some of the empirical\nevidence for the existence of power-law forms and the theories proposed to\nexplain them.",
        "category": "cond-mat"
    },
    {
        "text": "Van Hove Exciton-Cageons and High-T$_c$ Superconductivity: XB: Polaronic\n  Coupling in the Doped Material: A purely ionic interpretation of the tilting mode instabilities in\nLa$_{2-x}$A$ _x$CuO$_4$ (A=Sr,Ba) is shown to be not self-consistent: the\ndominant factor influencing the doping dependence of the interlayer mismatch is\nthe large change in the Cu-O bond length, which in turn leads to a strong\nelectron-phonon coupling. This coupling is closely related to the vHs-JT\neffect. This new insight clarifies the role of the tilt-mode instabilities. The\nmain JT coupling is {\\it not} to these modes, but to the in-plane O-O bond\nstretching modes which split the vHs degeneracy. However, as these modes\nsoften, they couple to the lower-lying tilt modes, so that the ultimate\ninstability has a finite tilt component. The bond stretch modes have a large,\nlinear coupling to electrons, with clear polaronic effects. A striking result\nof this is that there will be a large polaronic band narrowing near the vHs,\nwhether or not the vHs is near the Fermi level. This vHs-localized band\nnarrowing provides a natural explanation for the common occurence of extended\nvHs's.",
        "category": "cond-mat"
    },
    {
        "text": "NMR properties of a one-dimesional Cu-O model: We obtain the Knight shifts and the relaxation rates related to the Fermi\ncontact interaction term for a one-dimensional Cu-O model using bosonization\ntechnique. We consider the small interaction limit at half-filling and away\nfrom half-filling. In this framework we predict that the antiferromagnetic\ncontribution to the relaxation rate of the nuclear oxygen spin is completely\nsuppressed even away from half-filling, when the temperature is low enough. In\nthe strong interaction limit at half-filling we compute the effective Fermi\ncontact interaction performing a Gutzwiller projection. Both limits suggest\nthat the one-dimensional versions of the Mila-Rice and of the Shastry scenarios\nof transferred hyperfine couplings which were proposed to explain the NMR\nmeasurements for High-T_c cuprates fail in a one-dimensional situation.",
        "category": "cond-mat"
    },
    {
        "text": "Topological Transitions in a Model for Proximity Induced\n  Superconductivity: Using a prototype model for proximity induced superconductivity on a bilayer\nsquare lattice, we show that interlayer tunneling can drive change in topology\nof the Bogoliubov quasiparticle bands. Starting with topologically trivial\nsuperconductors, transitions to a non-trivial $p_x + {\\rm i} p_y$ state and\nback to another trivial state are discovered. We characterize these phases in\nterms of edge-state spectra and Chern indices. We show that these transitions\ncan also be controlled by experimentally viable control parameters, the\nbandwidth of the metallic layer and the gate potential. Insights from our\nresults on a simple model for proximity induced superconductivity may open up a\nnew route to discover topological superconductors.",
        "category": "cond-mat"
    },
    {
        "text": "Instabilities of micro-phase separated Coulombic systems in constant\n  electric fields: Mixtures of near-symmetric oppositely charged components with strong\nattractive short range interactions exhibit ordered lamellar phases at low\ntemperatures. In the strong segregation limit the state of these systems can be\ndescribed by the location of the interfaces between the components. It has\npreviously been shown that these systems are stable against small deformations\nof the interfaces. We examine their stability in the presence of a uniform\nelectric field. When the field is perpendicular to the lamellae, the system is\nunstable against long wavelength deformations for all non-zero values of the\nexternal field. A field parallel to the lamellae produces deformed but\npersistent interfaces. In a finite thickness system, onset of an external\nperpendicular field modifies the ground state. Flow between the old and new\nground states requires the destruction of the original interfaces; this\ndestruction proceeds through the instabilities identified in the bulk case. We\nexamine the possibility of dynamical stabilization of structures by means of\noscillating fields.",
        "category": "cond-mat"
    },
    {
        "text": "Signatures of a topological Weyl loop in Co$_3$Sn$_2$S$_2$: The search for novel topological phases of matter in quantum magnets has\nemerged as a frontier of condensed matter physics. Here we use state-of-the-art\nangle-resolved photoemission spectroscopy (ARPES) to investigate single\ncrystals of Co$_3$Sn$_2$S$_2$ in its ferromagnetic phase. We report for the\nfirst time signatures of a topological Weyl loop. From fundamental symmetry\nconsiderations, this magnetic Weyl loop is expected to be gapless if spin-orbit\ncoupling (SOC) is strictly zero but gapped, with possible Weyl points, under\nfinite SOC. We point out that high-resolution ARPES results to date cannot\nunambiguously resolve the SOC gap anywhere along the Weyl loop, leaving open\nthe possibility that Co$_3$Sn$_2$S$_2$ hosts zero Weyl points or some non-zero\nnumber of Weyl points. On the surface of our samples, we further observe a\npossible Fermi arc, but we are unable to clearly verify its topological nature\nusing the established counting criteria. As a result, we argue that from the\npoint of view of photoemission spectroscopy the presence of Weyl points and\nFermi arcs in Co$_3$Sn$_2$S$_2$ remains ambiguous. Our results have\nimplications for ongoing investigations of Co$_3$Sn$_2$S$_2$ and other\ntopological magnets.",
        "category": "cond-mat"
    },
    {
        "text": "Bilayer Isotropic Thermal Cloak: Invisibility has attracted intensive research in various communities, e.g.,\noptics, electromagnetics, acoustics, thermodynamics, etc. However, the most of\nthem have only been experimentally achieved by virtue of simplified approaches\ndue to their inhomogeneous and extreme parameters imposed by\ntransformation-optic method, and usually require challenging realization with\nmetamaterials. In this paper, we demonstrate an advanced bilayer thermal cloak\nwith naturally available materials first time. This scheme, directly from\nthermal conduction equation, has been validated as an exact cloak rather than a\nreduced one, and we experimentally confirmed its perfect performance\n(heat-front maintenance and heat protection) in an actual setup. The proposed\nscheme may open a new avenue to control the diffusive heat flow in ways\ninconceivable with phonons.",
        "category": "cond-mat"
    },
    {
        "text": "Eigenvector Dreaming: Among the performance-enhancing procedures for Hopfield-type networks that\nimplement associative memory, Hebbian Unlearning (or dreaming) strikes for its\nsimplicity and its clear biological interpretation. Yet, it does not easily\nlend itself to a clear analytical understanding. Here we show how Hebbian\nUnlearning can be effectively described in terms of a simple evolution of the\nspectrum and the eigenvectors of the coupling matrix. We use these ideas to\ndesign new dreaming algorithms that are effective from a computational point of\nview, and are analytically far more transparent than the original scheme.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamic Length Scale and Weakest Link Behavior in Crystal Plasticity: Plastic deformation of heterogeneous solid structures is often characterized\nby random intermittent local plastic events. On the mesoscale this feature can\nbe represented by a spatially fluctuating local yield threshold. Here we study\nthe validity of such an approach and the ideal choice for the size of the\nrepresentative volume element for crystal plasticity in terms of a discrete\ndislocation model. We find that the number of links representing possible\nsources of plastic activity exhibits anomalous (super-extensive) scaling which\ntends to extensive scaling (often assumed in weakest-link models) if quenched\nshort-range interactions are introduced. The reason is that the interplay\nbetween long-range dislocation interactions and short-range quenched disorder\ndestroys scale-free dynamical correlations leading to event localization with a\ncharacteristic length-scale. Several methods are presented to determine the\ndynamic length-scale that can be generalized to other types of heterogeneous\nmaterials.",
        "category": "cond-mat"
    },
    {
        "text": "Nonlinear twistoptics at symmetry-broken interfaces: Broken symmetries induce strong nonlinear optical responses in materials and\nat interfaces. Twist angle can give complete control over the presence or lack\nof inversion symmetry at a crystal interface, and is thus an appealing knob for\ntuning nonlinear optical systems. In contrast to conventional nonlinear\ncrystals with rigid lattices, the weak interlayer coupling in van der Waals\n(vdW) heterostructures allows for arbitrary selection of twist angle, making\nnanomechanical manipulation of fundamental interfacial symmetry possible within\na single device. Here we report highly tunable second harmonic generation (SHG)\nfrom nanomechanically rotatable stacks of bulk hexagonal boron nitride (BN)\ncrystals, and introduce the term twistoptics to describe studies of optical\nproperties in dynamically twistable vdW systems. We observe SHG intensity\nmodulated by a factor of more than 50, polarization patterns determined by\nmoir\\'e interface symmetry, and enhanced conversion efficiency for bulk\ncrystals by stacking multiple pieces of BN joined by symmetry-broken\ninterfaces. Our study provides a foundation for compact twistoptics\narchitectures aimed at efficient, scalable, and tunable frequency-conversion,\nand demonstrates SHG as a robust probe of buried vdW interfaces.",
        "category": "cond-mat"
    },
    {
        "text": "Chain decay and rates disorder in the totally asymmetric simple\n  exclusion process: We theoretically study the Totally Asymmetric Exclusion Process (TASEP) with\nquenched jumping rates disorder and finite lifetime chain. TASEP is widely used\nto model the translation of messenger RNAs by Ribosomes in protein synthesis.\nSince the exact solution of the TASEP model is analytically and computationally\nintractable for biologically relevant systems parameters, the canonical\nMean-Field (MF) approaches of solving coupled non-linear differential equations\nis also computational expensive for the scale of relevant biological data\nanalysis. In this article, we provide alternative approach to computing the MF\nsteady state solution via a computationally efficient system of non-linear\nalgebraic equations. We further outline a framework for including correlations\nprogressively via the exact solution of small size TASEP system. Leading order\napproximation in the biologically relevant entry rate limited regime shows\nremarkable agreement with the full Monte-Carlo simulation result for a wide\nrange of system parameter space. These results could be of importance to the\nkinetic rates inference in Ribo-Seq data analysis and other related problems.",
        "category": "cond-mat"
    },
    {
        "text": "rf SQUID metamaterials: An rf superconducting quantum interference device (SQUID) array in an\nalternating magnetic field is investigated with respect to its effective\nmagnetic permeability, within the effective medium approximation. This system\nacts as an inherently nonlinear magnetic metamaterial, leading to negative\nmagnetic response, and thus negative permeability, above the resonance\nfrequency of the individual SQUIDs. Moreover, the permeability exhibits\noscillatory behavior at low field intensities, allowing its tuning by a slight\nchange of the intensity of the applied field.",
        "category": "cond-mat"
    },
    {
        "text": "Hydrodynamics of granular gases of inelastic and rough hard disks or\n  spheres. II. Stability analysis: Conditions for the stability under linear perturbations around the\nhomogeneous cooling state are studied for dilute granular gases of inelastic\nand rough hard disks or spheres with constant coefficients of normal ($\\alpha$)\nand tangential ($\\beta$) restitution. After a formally exact linear stability\nanalysis of the Navier--Stokes--Fourier hydrodynamic equations in terms of the\ntranslational ($d_t$) and rotational ($d_r$) degrees of freedom, the transport\ncoefficients derived in the companion paper [A. Meg\\'ias and A. Santos,\n\"Hydrodynamics of granular gases of inelastic and rough hard disks or spheres.\nI. Transport coefficients,\" Phys. Rev. E 104, 034901 (2021)] are employed.\nKnown results for hard spheres [V. Garz\\'o, A. Santos, and G. M. Kremer, Phys.\nRev. E 97, 052901 (2018)] are recovered by setting $d_t=d_r=3$, while novel\nresults for hard disks ($d_t=2$, $d_r=1$) are obtained. In the latter case, a\nhigh-inelasticity peculiar region in the $(\\alpha,\\beta)$ parameter space is\nfound, inside which the critical wave number associated with the longitudinal\nmodes diverges. Comparison with event-driven molecular dynamics simulations for\ndilute systems of hard disks at $\\alpha=0.2$ shows that this theoretical region\nof absolute instability may be an artifact of the extrapolation to high\ninelasticity of the approximations made in the derivation of the transport\ncoefficients, although it signals a shrinking of the conditions for stability.\nIn the case of moderate inelasticity ($\\alpha=0.7$), however, a good agreement\nbetween the theoretical predictions and the simulation results is found.",
        "category": "cond-mat"
    },
    {
        "text": "Electrically tunable multi-terminal SQUID-on-tip: We present a new nanoscale superconducting quantum interference device\n(SQUID) whose interference pattern can be shifted electrically in-situ. The\ndevice consists of a nanoscale four-terminal/four-junction SQUID fabricated at\nthe apex of a sharp pipette using a self-aligned three-step deposition of Pb.\nIn contrast to conventional two-terminal/two-junction SQUIDs that display\noptimal sensitivity when flux biased to about a quarter of the flux quantum,\nthe additional terminals and junctions allow optimal sensitivity at arbitrary\napplied flux, thus eliminating the magnetic field \"blind spots\". We demonstrate\nspin sensitivity of 5 to 8 $\\mu_B/\\text{Hz}^{1/2}$ over a continuous field\nrange of 0 to 0.5 T, with promising applications for nanoscale scanning\nmagnetic imaging.",
        "category": "cond-mat"
    },
    {
        "text": "Domain wall architecture in tetragonal ferroelectric thin films: Domain walls in ferroelectrics exhibit a plethora of phases and\nfunctionalities not found in the bulk. The interplay of electrostatic,\nchemical, topological, and distortive inhomogeneities at the walls can be so\ncomplex, however, that this obstructs their technological performance. In\ntetragonal ferroelectrics like PbZrxTi1-xO3, for example, the desired\nfunctional 180{\\deg} domain walls within out-of-plane-polarized c-domains are\ninterspersed by in-plane-polarized a-domains and the associated network of\ndomain walls remains challenging to analyze. Here we use a combination of STEM\nand optical second harmonic generation (SHG) to determine the relation between\nstrain, film thickness, local electric fields and the resulting domain and\ndomain-wall structures across the entire thickness of a set of PZT films. We\nquantify the distribution of a-domains in the c-domain matrix of the films.\nUsing locally applied electric fields we control the a/c distribution and\ninduce the technologically preferable 180{\\deg} domain walls. We find that\nthese voltage induced walls are tilted and exhibit a mixed Ising-N\\'eel type\ntransverse rotation of polarization across the wall with a specific nonlinear\noptical response.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of Giant Quantized Phonon Modes in Graphene via Tunneling\n  Spectra: Phonons, the fundamental vibrational modes of a crystal lattice, play a\ncrucial role in determining electronic properties of materials through\nelectron-phonon interaction. However, it has proved difficult to directly probe\nthe phonon modes of materials in electrical measurements. Here, we report the\nobservation of giant quantized phonon peaks of the K and K out-of-plane phonon\nin graphene monolayer in magnetic fields via tunneling spectra, which are\nusually used to measure local electronic properties of materials. A\nperpendicular magnetic field quantizes massless Dirac fermions in graphene into\ndiscrete Landau levels (LLs). We demonstrate that emission or absorption of\nphonons of quasiparticles in the LLs of graphene generates a new sequence of\ndiscrete states: the quantized phonon modes. In our tunneling spectra, the\nintensity of the observed phonon peaks is about 50 times larger than that of\nthe LLs because that the K and K out-of-plane phonon opens an inelastic\ntunneling channel. We also show that it is possible to switch on off the\nquantized phonon modes at nanoscale by controlling interactions between\ngraphene and the supporting substrate.",
        "category": "cond-mat"
    },
    {
        "text": "Rheology and Contact Lifetime Distribution in Dense Granular Flows: We study the rheology and distribution of interparticle contact lifetimes for\ngravity-driven, dense granular flows of non-cohesive particles down an inclined\nplane using large-scale, three dimensional, granular dynamics simulations.\nRather than observing a large number of long-lived contacts as might be\nexpected for dense flows, brief binary collisions predominate. In the hard\nparticle limit, the rheology conforms to Bagnold scaling, where the shear\nstress is quadratic in the strain rate. As the particles are made softer,\nhowever, we find significant deviations from Bagnold rheology; the material\nflows more like a viscous fluid. We attribute this change in the collective\nrheology of the material to subtle changes in the contact lifetime distribution\ninvolving the increasing lifetime and number of the long-lived contacts in the\nsofter particle systems.",
        "category": "cond-mat"
    },
    {
        "text": "Fermion Parity Flips and Majorana Bound States at twist defects in\n  Superconducting Fractional Topological Phases: In this paper we consider a layered heterostructure of an Abelian\ntopologically ordered state (TO), such as a fractional Chern insulator/quantum\nHall state with an s-wave superconductor in order to explore the existence of\nnon-Abelian defects. In order to uncover such defects we must augment the\noriginal TO by a $\\mathbb{Z}_2$ gauge theory sector coming from the s-wave SC.\nWe first determine the extended TO for a wide variety of fractional quantum\nHall or fractional Chern insulator heterostructures. We prove the existence of\na general anyon permutation symmetry (AS) that exists in any fermionic Abelian\nTO state in contact with an s-wave superconductor. Physically this permutation\ncorresponds to adding a fermion to an odd flux vortices (in units of $h/2e$) as\nthey travel around the associated topological (twist) defect. As such, we call\nit a fermion parity flip AS. We consider twist defects which mutate anyons\naccording to the fermion parity flip symmetry and show that they can be\nrealized at domain walls between distinct gapped edges or interfaces of the TO\nsuperconducting state. We analyze the properties of such defects and show that\nfermion parity flip twist defects are always associated with Majorana zero\nmodes. Our formalism also reproduces known results such as\nMajorana/parafermionic bound states at superconducting domain walls of\ntopological/Fractional Chern insulators when twist defects are constructed\nbased on charge conjugation symmetry. Finally, we briefly describe more exotic\ntwist liquid phases obtained by gauging the AS where the twist defects become\ndeconfined anyonic excitations.",
        "category": "cond-mat"
    },
    {
        "text": "Revealing the nature of defects in quasi free standing mono-layer\n  graphene on SiC(0001) by means of Density Functional Theory: Quasi free standing monolayer graphene (QFMLG) grown on SiC by selective Si\nevaporation from the Si-rich SiC(0001) face and H intercalation displays\nirregularities in STM and AFM analysis, appearing as localized features, which\nwe previously identified as vacancies in the H layer coverage [Y Murata, et al.\nNano Res, in press, DOI: 10.1007/s12274-017-1697-x]. The size, shape,\nbrightness, location, and concentration of these features, however, are\nvariable, depending on the hydrogenation conditions. In order to shed light on\nthe nature of these features, in this work we perform a systematic Density\nFunctional Theory study on the structural and electronic properties of QFMLG\nwith defects in the H coverage arranged in different configurations including\nup to 13 vacant H atoms, and show that these generate localized electronic\nstates with specific electronic structure. Based on the comparison of simulated\nand measured STM images we are able to associate different vacancies of large\nsize (7-13 missing H) to the different observed features. The presence of large\nvacancies is in agreement with the tendency of single H vacancies to aggregate,\nas demonstrated here by DFT results. This gives some hints into the\nhydrogenation process. Our work unravels the structural diversity of defects of\nH coverage in QFMLG and provides operative ways to interpret the variety in the\nSTM images. The energy of the localized states generated by these vacancies is\ntunable by means of their size and shape, suggesting applications in nano- and\nopto-electronics.",
        "category": "cond-mat"
    },
    {
        "text": "Stability conditions for a large anharmonic bipolaron: A large polaron is a quasiparticle that consists of a nearly free electron\ninteracting with the phonons of a material, whose lattice parameters are much\nsmaller than the polaron scale. The electron-phonon interaction also leads to\nan attractive interaction between electrons, which can allow two polarons to\npair up and form a bipolaron. It has been shown that large bipolarons can form\nin theory due to strong 1-electron-1-phonon coupling, but they have not been\nseen in real materials because the critical value of the required\nelectron-phonon interaction is too large. Here, we investigate the effect of\n1-electron-2-phonon coupling on the large bipolaron problem.\n  Starting from a generalization of the Fr\\\"ohlich Hamiltonian that includes\nboth the standard 1-electron-1-phonon interaction as well as an anharmonic\n1-electron-2-phonon interaction, we use the path integral method to find a\nsemi-analytical upper bound for the bipolaron energy that is valid at all\nvalues of the Fr\\\"ohlich coupling strength $\\alpha$. We find the bipolaron\nphase diagram and conditions for the bipolaron stability by comparing the\nbipolaron energy to the energy of two free polarons. The critical value of the\nFr\\\"ohlich coupling strength $\\alpha_{\\text{crit}}$ is calculated as a function\nof the strength of the 1-electron-2-phonon interaction. The results suggest\nthat large bipolaron formation is more likely in materials with significant\n1-electron-2-phonon interaction as well as strong 1-electron-1-phonon\ninteraction, such as strontium titanate.",
        "category": "cond-mat"
    },
    {
        "text": "Comments on \"Competition Between Fractional Quantum Hall Liquid ...\", by\n  G. Gervais, L. W. Engel, H. L. Stormer, D. C. Tsui, et al (cond-mat/0402169): The quantum Hall effect in ultra-high mobility GaAs/AlGaAs has been measured\nand plateaus are found at many different fractions. The resistivity is\nquantized as \\rho =h/ie^2 where i exhibits many different values. The fractions\n5/3, 8/5, 11/7, 14/9, 17/11 fit the formula, i=3p\\pm 2/(2p \\pm 1) and it is\nclaimed that 2p flux quanta are attached to the electron. The fractions 4/11,\n7/11, 12/7, 13/8 and 15/11 do not fit the expression for i, even then the\nauthors insist that flux quanta are attached to the electron and hence\ncomposite fermions (CF) are formed. We report that the interpretation of the\nexperimental data in terms of CF is incorrect.",
        "category": "cond-mat"
    },
    {
        "text": "Protected edge modes without symmetry: We discuss the question of when a gapped 2D electron system without any\nsymmetry has a protected gapless edge mode. While it is well known that systems\nwith a nonzero thermal Hall conductance, $K_H \\neq 0$, support such modes, here\nwe show that robust modes can also occur when $K_H = 0$ -- if the system has\nquasiparticles with fractional statistics. We show that some types of\nfractional statistics are compatible with a gapped edge, while others are\nfundamentally incompatible. More generally, we give a criterion for when an\nelectron system with abelian statistics and $K_H = 0$ can support a gapped\nedge: we show that a gapped edge is possible if and only if there exists a\nsubset of quasiparticle types $M$ such that (1) all the quasiparticles in $M$\nhave trivial mutual statistics, and (2) every quasiparticle that is not in $M$\nhas nontrivial mutual statistics with at least one quasiparticle in $M$. We\nderive this criterion using three different approaches: a microscopic analysis\nof the edge, a general argument based on braiding statistics, and finally a\nconformal field theory approach that uses constraints from modular invariance.\nWe also discuss the analogous result for 2D boson systems.",
        "category": "cond-mat"
    },
    {
        "text": "Non-Fermi Liquid Fixed Point in 2+1 Dimensions: We construct models of excitations about a Fermi surface that display\ncalculable deviations from Fermi liquid behavior in the low-energy limit. They\narise as a consequence of coupling to a Chern-Simons gauge field, whose\nfluctations are controlled through a ${1\\over{k^x}}$ interaction. The Fermi\nliquid fixed point is shown to be unstable in the infrared for $x<1$, and an\ninfrared-stable fixed point is found in a $(1-x)$-expansion, analogous to the\n$\\epsilon$-expansion of critical phenomena. $x=1$ corresponds to Coulomb\ninteractions, and in this case we find a logarithmic approach to zero coupling.\nWe describe the low-energy behavior of metals in the universality class of the\nnew fixed point, and discuss its possible application to the compressible\n$\\nu={1\\over2}$ quantum Hall state and to the normal state of copper-oxide\nsuperconductors.",
        "category": "cond-mat"
    },
    {
        "text": "Factors Enabling Delocalized Charge-Carriers in Pnictogen-Based Solar\n  Absorbers: In-depth Investigation into CuSbSe2: Inorganic semiconductors based on heavy pnictogen cations (Sb3+ and Bi3+)\nhave gained significant attention as potential nontoxic and stable alternatives\nto lead-halide perovskites for solar cell applications. A limitation of these\nnovel materials, which is being increasingly commonly found, is carrier\nlocalization, which substantially reduces mobilities and diffusion lengths.\nHerein, the layered p\\v{r}\\'ibramite CuSbSe2 is investigated and discovered to\nhave delocalized free carriers, as shown through optical pump terahertz probe\nspectroscopy and temperature-dependent mobility measurements. Using a\ncombination of theory and experiment, it is found that the underlying factors\nare: 1) weak coupling to acoustic phonons due to low deformation potentials, as\nlattice distortions are primarily accommodated through rigid inter-layer\nmovement rather than straining inter-atomic bonds, and 2) weak coupling to\noptical phonons due to the ionic contributions to the dielectric constant being\nlow compared to electronic contributions. This work provides important insights\ninto how pnictogen-based semiconductors avoiding carrier localization could be\nidentified.",
        "category": "cond-mat"
    },
    {
        "text": "Relationship between Population Dynamics and the Self-Energy in Driven\n  Non-Equilibrium Systems: We compare the decay rates of excited populations directly calculated within\na Keldysh formalism to the equation of motion of the population itself for a\nHubbard-Holstein model in two dimensions. While it is true that these two\napproaches must give the same answer, it is common to make a number of\nsimplifying assumptions within the differential equation for the populations\nthat allows one to interpret the decay in terms of hot electrons interacting\nwith a phonon bath. Here we show how care must be taken to ensure an accurate\ntreatment of the equation of motion for the populations due to the fact that\nthere are identities that require cancellations of terms that naively look like\nthey contribute to the decay rates. In particular, the average time dependence\nof the Green's functions and self-energies plays a pivotal role in determining\nthese decay rates.",
        "category": "cond-mat"
    },
    {
        "text": "Collective excitations of the Chern-insulator states in commensurate\n  double moir\u00e9 superlattices of twisted bilayer graphene on hexagonal boron\n  nitride: We study the collective excitation modes of the Chern insulator states in\nmagic-angle twisted bilayer graphene aligned with hexagonal boron nitride\n(TBG/BN) at odd integer fillings ($\\nu$) of the flat bands. For the $1 \\times\n1$ commensurate double moir\\'{e} superlattices in TBG/BN at three twist angles\n($\\theta'$) between BN and graphene, self-consistent Hartree-Fock calculations\nshow that the electron-electron interaction and the broken $C_{2z}$ symmetry\nlead to the Chern-insulator ground states with valley-spin flavor polarized HF\nbands at odd $\\nu$. In the active-band approximation, the HF bands in the same\nflavor of TBG/BN are much more separated than those of the pristine TBG with\nTBG/BN having a larger intra-flavor band gap so that the energies of the lowest\nintra-flavor exciton modes of TBG/BN computed within the time-dependent HF\nmethod are much higher than those of TBG and reach about 20 meV, and the\nexciton wavefunctions of TBG/BN become less localized than those of TBG. The\ninter-flavor valley-wave modes in TBG/BN have excitation energies higher than\n2.5 meV which is also much larger than that of TBG, while the spin-wave modes\nall have zero excitation gap. In contrast to TBG with particle-hole symmetric\nexcitation modes for positive and negative $\\nu$, the excitation spectrums and\ngaps of TBG/BN at positive $\\nu$ are rather different from those at negative\n$\\nu$. The quantitative behavior of the excitation spectrum of TBG/BN also\nvaries with $\\theta'$. Full HF calculations demonstrate that more HF bands\nbesides the two central bands can have rather large contributions from the\nsingle-particle flat-band states, then the lowest exciton modes that determine\nthe optical properties of the Chern insulator states in TBG/BN are generally\nthe ones between the remote and flat-like bands, while the valley-wave modes\nhave similar energies as those in the active-band approximation.",
        "category": "cond-mat"
    },
    {
        "text": "Spontaneous Charge Oscillations in Dielectric Confined Quasi-2D Systems: We report spontaneous electric field and charge oscillations in dielectric\nconfined Quasi-2D charged systems. A simple relationship is found for the\noscillation wave number, which is solely determined by the dielectric mismatch\nand the length scale of confinement. We analytically show that the emergence of\ncharge/field oscillation is due to the arising of a first-order pole in the\nquasi-2D Green's function. The oscillatory behavior is further validated\nnumerically, and its influence on collective behaviors of the confined\nparticles is studied via computer simulations. Interestingly, the substrate\npermittivity alone can trigger spontaneous formations of lattice structures,\nwhich may provide new insights in the study of Quasi-2D systems and the design\nof future nanodevices.",
        "category": "cond-mat"
    },
    {
        "text": "Self-motile colloidal particles: from directed propulsion to random walk: The motion of an artificial micro-scale swimmer that uses a chemical reaction\ncatalyzed on its own surface to achieve autonomous propulsion is fully\ncharacterized experimentally. It is shown that at short times, it has a\nsubstantial component of directed motion, with a velocity that depends on the\nconcentration of fuel molecules. At longer times, the motion reverts to a\nrandom walk with a substantially enhanced diffusion coefficient. Our results\nsuggest strategies for designing artificial chemotactic systems.",
        "category": "cond-mat"
    },
    {
        "text": "How Silicon and Boron Dopants Govern the Cryogenic Scintillation\n  Properties of N-type GaAs: This paper is the first report describing how the concentrations of silicon\nand boron govern the cryogenic scintillation properties of n-type GaAs. It\nshows that valence band holes are promptly trapped on radiative centers and\nthen combine radiatively with silicon donor band electrons at rates that\nincrease with the density of free carriers. It also presents the range of\nsilicon and boron concentrations needed for efficient light emission under\nX-ray excitation, which along with its low band gap and apparent absence of\nafterglow, make scintillating GaAs suitable for the detection of rare,\nlow-energy electronic excitations from interacting dark matter particles. A\ntotal of 29 samples from four different suppliers were studied. Luminosities\nand timing responses were measured for the four principal emission bands\ncentered at 860, 930, 1070, and 1335 nm, and for the total emissions.\nExcitation pulses of 40 kVp X-rays were provided by a light-excited X-ray tube\ndriven by an ultra-fast laser. Scintillation emissions from 800 to 1350 nm were\nmeasured using an InGaAs photomultiplier. Within the concentration ranges of\nfree carriers from 2 x 10^16/cm3 to 6 x 10^17/cm3 and boron from 1.5 x\n10^18/cm3 to 6 x 10^18/cm3, nine samples have luminosities > 70 photons/keV and\ntwo have luminosities > 110 photons/keV. Other samples in that range have lower\nluminosities due to higher concentrations of non-radiative centers. The decay\ntimes decrease by typically a factor of ten with increasing free carrier\nconcentrations from 10^17/cm3 to 2 x 10^18/cm3.",
        "category": "cond-mat"
    },
    {
        "text": "Superfluid Turbulence in the Kelvin Wave Cascade Regime: Theoretical considerations are made of superfluid turbulence in the Kelvin\nwave cascade regime at low temperatures (T < 1K) and length scales of the order\nor smaller than the intervortical distance. The energy spectrum is shown to be\nin accord with the Kolmogorov scaling. The vortex line decay equation is shown\nto have an underlying Hamiltonian framework. Effects of spatial intermittency\n(exhibited in laboratory experiments) on superfluid turbulence are incorporated\nvia the fractal nature of the vortex lines, for length scales of the order or\nsmaller than the intervortical distance. The spatial intermittency effects are\nshown to enhance the vortex line density L, for a given value of intervortex\nspacing L, and to provide for a mechanism commensurate with the enhanced\ndepolarization of vortex lines. The spatial intermittency is found to steepen\nthe energy spectrum in qualitative agreement with laboratory experiments and to\nenhance vortex line decay.",
        "category": "cond-mat"
    },
    {
        "text": "Computational Pipeline to probe NaV1.7 gain-of-functions variants in\n  neuropathic painful syndromes: Applications of machine learning and graph theory techniques to neuroscience\nhave witnessed an increased interest in the last decade due to the large data\navailability and unprecedented technology developments. Their employment to\ninvestigate the effect of mutational changes in genes encoding for proteins\nmodulating the membrane of excitable cells, whose biological correlates are\nassessed at electrophysiological level, could provide useful predictive clues.\nWe apply this concept to the analysis of variants in sodium channel NaV1.7\nsubunit found in patients with chronic painful syndromes, by the implementation\nof a dedicated computational pipeline empowering different and complementary\ntechniques including homology modeling, network theory, and machine learning.\nBy testing three templates of different origin and sequence identities, we\nprovide an optimal condition for its use. Our findings reveal the usefulness of\nour computational pipeline in supporting the selection of candidates for cell\nelectrophysiology assay and with potential clinical applications.",
        "category": "cond-mat"
    },
    {
        "text": "Electrophoresis of active Janus particles: We theoretically consider the dynamics of a self-propelled active Janus motor\nmoving in an external electric field. The external field can manipulate the\nroute of a Janus particle and enforce it to move towards the desired targets.\nTo investigate the trajectory of this active motor, we use a perturbative\nscheme. At the leading orders of surface activity of the Janus particle and\nalso the external field, the orientational dynamics of the Janus particles\nbehave like a mathematical pendulum with an angular the velocity that is\nsensitive to both the electric field and surface activity of the motor.",
        "category": "cond-mat"
    },
    {
        "text": "Silicon in the Quantum Limit: Quantum Computing and Decoherence in\n  Silicon Architectures: Semiconductor architectures hold promise for quantum information processing\n(QIP) applications due to their large industrial base and perceived scalability\npotential. Electron spins in silicon in particular may be an excellent\narchitecture for QIP and also for spin electronics (spintronics) applications.\nWhile the charge of an electron is easily manipulated by charged gates, the\nspin degree of freedom is well isolated from charge fluctuations. Inherently\nsmall spin-orbit coupling and the existence of a spin-zero Si isotope\nfacilitate long single spin qubit coherence times. Here we consider the\nrelaxation properties of localized electronic states in silicon due to donors,\nquantum wells, and quantum dots, including effects due to phonons and Rashba\nspin-orbit coupling. Our analysis is impeded by the complicated, many-valley\nband structure of silicon and previously unaddressed physics in silicon quantum\nwells. We find that electron spins in silicon and especially strained silicon\nhave excellent decoherence properties. Where possible we compare with\nexperiment to test our theories. We go beyond issues of coherence in a quantum\ncomputer to problems of control and measurement. Precisely what makes spin\nrelaxation so long in semiconductor architectures makes spin measurement so\ndifficult. To address this, we propose a new scheme for spin readout which has\nthe added benefit of automatic spin initialization, a vital component of\nquantum computing and quantum error correction. Our results represent important\npractical milestones on the way to the design and construction of a\nsilicon-based quantum computer.",
        "category": "cond-mat"
    },
    {
        "text": "Optical absorption of non-interacting tight-binding electrons in a\n  Peierls-distorted chain at half band-filling: In this first of three articles on the optical absorption of electrons in\nhalf-filled Peierls-distorted chains we present analytical results for\nnon-interacting tight-binding electrons. We carefully derive explicit\nexpressions for the current operator, the dipole transition matrix elements,\nand the optical absorption for electrons with a cosine dispersion relation of\nband width $W$ and dimerization parameter $\\delta$. New correction\n(``$\\eta$''-)terms to the current operator are identified. A broad band-to-band\ntransition is found in the frequency range $W\\delta < \\omega < W$ whose shape\nis determined by the joint density of states for the upper and lower Peierls\nsubbands and the strong momentum dependence of the transition matrix elements.",
        "category": "cond-mat"
    },
    {
        "text": "On various levels of deterministic toy models for the Richardson cascade\n  in turbulence: The Desnyanski-Novikov shell model is a deterministic dynamical model for\nscalar velocities $v_t(n)$ defined on the one-dimensional-lattice $n=0,1,2,..$\nlabelling the length-scales $l_n=l_0 2^{-n}$, in order to describe the cascade\nof energy from the biggest scale where it is injected by some external forcing\ntowards the smaller scales where it is dissipated by viscosity. We describe the\ngeneralization of this model in two directions : (i) the\none-dimensional-lattice $n=0,1,2,..$ labelling the length-scales $l_n=l_0\n2^{-n}$ is replaced by a scale-spatial tree structure of nested cells in order\nto allow spatial heterogeneities between different coherent structures that are\nlocalized in different regions of the whole volume ; (ii) the scalar velocities\n$v_t(n)$ are replaced by 3D-vector velocities in order to take into account the\nvorticity in the dynamical equations and to include vortex-stretching effects.",
        "category": "cond-mat"
    },
    {
        "text": "Low-dimensional antiferromagnetic fluctuations in the heavy-fermion\n  paramagnetic ladder UTe$_2$: Inelastic-neutron-scattering measurements were performed on a single crystal\nof the heavy-fermion paramagnet UTe$_2$ above its superconducting temperature.\nWe confirm the presence of antiferromagnetic fluctuations with the\nincommensurate wavevector $\\mathbf{k}_1=(0,0.57,0)$. A quasielastic signal is\nfound, whose momentum-transfer dependence is compatible with fluctuations of\nmagnetic moments $\\mu\\parallel\\mathbf{a}$, with a sine-wave modulation of\nwavevector $\\mathbf{k}_1$ and in-phase moments on the nearest U atoms. Low\ndimensionality of the magnetic fluctuations, consequence of the ladder\nstructure, is indicated by weak correlations along the direction $\\mathbf{c}$.\nThese fluctuations saturate below the temperature $T_1^*\\simeq15$~K, in\npossible relation with anomalies observed in thermodynamic,\nelectrical-transport and nuclear-magnetic-resonance measurements. The absence\nor weakness of ferromagnetic fluctuations, in our data collected at\ntemperatures down to 2.1 K and energy transfers from 0.6 to 7.5 meV, is\nemphasized. These results constitute constraints for models of\nmagnetically-mediated superconductivity in UTe$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Scale invariance and universality of force networks in static granular\n  matter: Force networks form the skeleton of static granular matter. They are the key\ningredient to mechanical properties, such as stability, elasticity and sound\ntransmission, which are of utmost importance for civil engineering and\nindustrial processing. Previous studies have focused on the global structure of\nexternal forces (the boundary condition), and on the probability distribution\nof individual contact forces. The disordered spatial structure of the force\nnetwork, however, has remained elusive so far. Here we report evidence for\nscale invariance of clusters of particles that interact via relatively strong\nforces. We analyzed granular packings generated by molecular dynamics\nsimulations mimicking real granular matter; despite the visual variation, force\nnetworks for various values of the confining pressure and other parameters have\nidentical scaling exponents and scaling function, and thus determine a\nuniversality class. Remarkably, the flat ensemble of force configurations--a\nsimple generalization of equilibrium statistical mechanics--belongs to the same\nuniversality class, while some widely studied simplified models do not.",
        "category": "cond-mat"
    },
    {
        "text": "Phase Diagram and Snap-Off Transition for a Twisted Party Balloon: All children enjoy inflating balloons and twisting them into different shapes\nand animals. Snapping the balloon into two separate compartments is a necessary\nstep that bears resemblance to the pinch-off phenomenon for water droplet\ndetached from the faucet. In addition to testing whether balloons exhibit the\nproperties of self-similarity and memory effect that are often associated with\nthe latter event, we determine their phase diagram by experiments. It turns out\nthat a common party balloon does not just snap. They in fact can assume five\nmore shapes, i.e., straight, necking, wrinkled, helix, and supercoil, depending\non the twist angle and ratio of its length and diameter. Moreover, history also\nmatters due to their prominent hysteresis. One may shift the phase boundary\nor/and reshuffle the phases by untwisting or lengthening the balloon at\ndifferent twist angle and initial length. Heuristic models are provided to\nobtain analytic expressions for the phase boundaries.",
        "category": "cond-mat"
    },
    {
        "text": "Tunneling Spin Injection into Single Layer Graphene (Supplementary\n  Information): We achieve tunneling spin injection from Co into single layer graphene (SLG)\nusing TiO2 seeded MgO barriers. A non-local magnetoresistance ({\\Delta}RNL) of\n130 {\\Omega} is observed at room temperature, which is the largest value\nobserved in any material. Investigating {\\Delta}RNL vs. SLG conductivity from\nthe transparent to the tunneling contact regimes demonstrates the contrasting\nbehaviors predicted by the drift-diffusion theory of spin transport.\nFurthermore, tunnel barriers reduce the contact-induced spin relaxation and are\ntherefore important for future investigations of spin relaxation in graphene.",
        "category": "cond-mat"
    },
    {
        "text": "Single crystal study of the layered heavy fermion compounds\n  Ce$_2$PdIn$_8$, Ce$_3$PdIn$_{11}$, Ce$_2$PtIn$_8$ and Ce$_3$PtIn$_{11}$: We report on single crystal growth and crystallographic parameters results of\nCe$_2$PdIn$_8$, Ce$_3$PdIn$_{11}$, Ce$_2$PtIn$_8$ and Ce$_3$PtIn$_{11}$. The\nPt-systems Ce$_2$PtIn$_8$ and Ce$_3$PtIn$_{11}$ are synthesized for the first\ntime. All these compounds are member of the Ce$_n$T$_m$In$_{3n+2m}$ (n = 1,\n2,..; m = 1, 2,.. and T = transition metal) to which the extensively studied\nheavy fermion superconductor CeCoIn$_5$ belongs. Single crystals have been\ngrown by In self-flux method. Differential scanning calorimetry studies were\nused to derive optimal growth conditions. Evidently, the maximum growth\nconditions for these materials should not exceed 750 $^{\\circ}$C. Single\ncrystal x-ray data show that Ce$_2$TIn$_8$ compounds crystallize in the\ntetragonal Ho$_2$CoGa$_8$ phase (space group P4/mmm) with lattice parameters a\n=4.6898(3) $\\AA$ and c =12.1490(8) $\\AA$ for the Pt-based one (Pd: a =\n4.6881(4) $\\AA$ and c = 12.2031(8) \\AA). The Ce$_3$TIn$_{11}$ compounds adopt\nthe Ce$_3$PdIn$_{11}$ structure with a = 4.6874(4) $\\AA$ and c = 16.8422(12)\n$\\AA$ for the Pt-based one (Pd: a = 4.6896 $\\AA$ and c = 16.891 \\AA). Specific\nheat experiments on Ce$_3$PtIn$_{11}$ and Ce$_3$PdIn$_{11}$ have revealed that\nboth compounds undergo two successive magnetic transitions at T$_1$ ~ 2.2 K\nfollowed by T$_N$ ~ 2.0 K and T$_1$ ~ 1.7 K and T$_N$ ~ 1.5 K, respectively.\nAdditionally, both compounds exhibit enhanced Sommerfeld coefficients yielding\n{\\gamma}$_{Pt}$ = 0.300 J/mol K$^2$ Ce ({\\gamma}$_{Pd}$ = 0.290 J/mol K$^2$\nCe), hence qualifying them as heavy fermion materials.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetization Plateaux in Bethe Ansatz Solvable Spin-S Ladders: We examine the properties of the Bethe Ansatz solvable two- and three-leg\nspin-$S$ ladders. These models include Heisenberg rung interactions of\narbitrary strength and thus capture the physics of the spin-$S$ Heisenberg\nladders for strong rung coupling. The discrete values derived for the\nmagnetization plateaux are seen to fit with the general prediction based on the\nLieb-Schultz- Mattis theorem. We examine the magnetic phase diagram of the\nspin-1 ladder in detail and find an extended magnetization plateau at the\nfractional value $<M > = {1/2}$ in agreement with the experimental observation\nfor the spin-1 ladder compound BIP-TENO.",
        "category": "cond-mat"
    },
    {
        "text": "Study of off-diagonal disorder using the typical medium dynamical\n  cluster approximation: We generalize the typical medium dynamical cluster approximation (TMDCA) and\nthe local Blackman, Esterling, and Berk (BEB) method for systems with\noff-diagonal disorder. Using our extended formalism we perform a systematic\nstudy of the effects of non-local disorder-induced correlations and of\noff-diagonal disorder on the density of states and the mobility edge of the\nAnderson localized states. We apply our method to the three-dimensional\nAnderson model with configuration dependent hopping and find fast convergence\nwith modest cluster sizes. Our results are in good agreement with the data\nobtained using exact diagonalization, and the transfer matrix and kernel\npolynomial methods.",
        "category": "cond-mat"
    },
    {
        "text": "Two-Particle Self-Consistent Approach to Anisotropic Superconductivity: A nonperturbative approach to anisotropic superconductivity is developed\nbased on the idea of two-particle self-consistent (TPSC) theory by Vilk and\nTremblay. A sum-rule which the momentum-dependent pairing susceptibility\nsatisfies is derived. An effective pairing interaction between quasiparticles\nis determined so that the susceptibility should fulfill this exact sum-rule, in\nwhich fluctuations belonging to different symmetries couple at finite momentum.\nIt is demonstrated that the mode coupling between d-wave and s-wave pairing\nfluctuations leads to suppression of the d-wave fluctuation near the Mott\ninsulator.",
        "category": "cond-mat"
    },
    {
        "text": "Chiral-symmetric Topological Origin of Nonlinear Fixed Points: Particle-hole symmetry and chiral symmetry play a pivotal role in multiple\nareas of physics, yet they remain un-studied in systems with nonlinear\ninteractions that are beyond Kerr-type. Here, we establish these two\nnon-spatial symmetries in systems with strong and general nonlinear\ninteractions. Chiral symmetry ensures the quantization of the Berry phase of\nnonlinear normal modes and categorizes the topological phases of nonlinear\ndynamics. We show edge modes that serve as topologically protected fixed points\nof chiral-symmetric nonlinear dynamics. Our theoretical framework paves the way\ntowards the topological classification of general nonlinear dynamics.",
        "category": "cond-mat"
    },
    {
        "text": "Competing magnetic fluctuations and orders in a multiorbital model of\n  doped SrCo$_2$As$_2$: We revisit the intriguing magnetic behavior of the paradigmatic itinerant\nfrustrated magnet $\\rm{Sr}\\rm{Co}_2\\rm{As}_2$, which shows strong and competing\nmagnetic fluctuations yet does not develop long-range magnetic order. By\ncalculating the static spin susceptibility $\\chi(\\mathbf{q})$ within a\nrealistic sixteen orbital Hubbard-Hund model, we determine the leading\ninstability to be ferromagnetic (FM). We then explore the effect of doping and\ncalculate the critical Hubbard interaction strength $U_c$ that is required for\nthe development of magnetic order. We find that $U_c$ decreases under electron\ndoping and with increasing Hund's coupling $J$, but increases rapidly under\nhole doping. This suggests that magnetic order could possibly emerge under\nelectron doping but not under hole doping, which agrees with experimental\nfindings. We map out the leading magnetic instability as a function of doping\nand Hund's coupling and find several antiferromagnetic phases in addition to\nFM. We also quantify the degree of itinerant frustration in the model and\nresolve the contributions of different orbitals to the magnetic susceptibility.\nFinally, we discuss the dynamic spin susceptibility, $\\chi(\\mathbf{q},\n\\omega)$, at finite frequencies, where we recover the anisotropy of the peaks\nat $\\mathbf{Q}_\\pi = (\\pi, 0)$ and $(0, \\pi)$ observed by inelastic neutron\nscattering that is associated with the phenomenon of itinerant magnetic\nfrustration. By comparing results between theory and experiment, we conclude\nthat the essential experimental features of doped SrCo$_2$As$_2$ are well\ncaptured by a Hubbard-Hund multiorbital model if one considers a small shift of\nthe chemical potential towards hole doping.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum weight: We introduce the concept of quantum weight as a fundamental property of\ninsulating states of matter that is encoded in the ground-state static\nstructure and measures quantum fluctuation in electrons' center of mass. We\nfind a sum rule that directly relates quantum weight -- a ground state property\n-- with the negative-first moment of the optical conductivity above the gap\nfrequency. Building on this connection to optical absorption, we derive both an\nupper bound and a lower bound on quantum weight in terms of electron density,\ndielectric constant, and energy gap. Therefore, quantum weight constitutes a\nkey material parameter that can be experimentally determined from X-ray\nscattering.",
        "category": "cond-mat"
    },
    {
        "text": "Zeno and anti-Zeno dynamics in spin-bath models: We investigate the quantum Zeno and anti-Zeno effects in spin bath models:\nthe spin-boson model and a spin-fermion model. We show that the Zeno-anti-Zeno\ntransition is critically controlled by the system-bath coupling parameter, the\nsame parameter that determines spin decoherence rate. We also discuss the\ncrossover in a biased system, at high temperatures, and for a nonequilibrium\nspin-fermion system, manifesting the counteracting roles of electrical bias,\ntemperature, and magnetic field on the spin decoherence rate.",
        "category": "cond-mat"
    },
    {
        "text": "The nature of the short wavelength excitations in vitreous silica:\n  X-Rays Brillouin scattering study: The dynamical structure factor (S(Q,E)) of vitreous silica has been measured\nby Inelastic X-ray Scattering varying the exchanged wavevector (Q) at fixed\nexchanged energy (E) - an experimental procedure that, contrary to the usual\none at constant Q, provides spectra with much better identified inelastic\nfeatures. This allows the first direct evidence of Brillouin peaks in the\nS(Q,E) of SiO_2 at energies above the Boson Peak (BP) energy, a finding that\nexcludes the possibility that the BP marks the transition from propagating to\nlocalised dynamics in glasses.",
        "category": "cond-mat"
    },
    {
        "text": "Electron-phonon coupling of Fe-adatom electron states on MgO/Ag(100): We study the strength of the electron-phonon interaction on Fe single adatoms\non MgO/Ag(100) based on many-body \\textit{ab-initio} spin collinear\ncalculations. In particular, we analyze the relative importance of the\nsubstrate and, among other results, we conclude that the interface electron\nstate of Ag(100) plays a prominent role in determining the electron-phonon\ncoupling of localized Fe electron states. The analysis of the hybridization of\nthe adatom with the substrate reveals qualitative differences for even or odd\ncoverages of MgO, affecting significantly the spectral structure and strength\nof the electron-phonon coupling. Our calculations indicate that the\nelectron-phonon interaction is very strong for $\\le$~1 layers of MgO, while it\nis sharply suppressed for larger coverages, a trend that is consistent with\nrecent experimental findings.",
        "category": "cond-mat"
    },
    {
        "text": "From Luttinger liquid to Mott insulator: the correct low-energy\n  description of the one-dimensional Hubbard model by an unbiased variational\n  approach: We show that a particular class of variational wave functions reproduces the\nlow-energy properties of the Hubbard model in one dimension. Our approach\ngeneralizes to finite on-site Coulomb repulsion the fully-projected wave\nfunction proposed by Hellberg and Mele [Phys. Rev. Lett. {\\bf 67}, 2080 (1991)]\nfor describing the Luttinger-liquid behavior of the doped $t{-}J$ model. Within\nour approach, the long-range Jastrow factor emerges from a careful minimization\nof the energy, without assuming any parametric form for the long-distance tail.\nSpecifically, in the conducting phase of the Hubbard model at finite hole\ndoping, we obtain the correct power-law behavior of the correlation functions,\nwith the exponents predicted by the Tomonaga-Luttinger theory. By decreasing\nthe doping, the insulating phase is reached with a continuous change of the\nsmall-$q$ part of the Jastrow factor.",
        "category": "cond-mat"
    },
    {
        "text": "Noncommutative generalized Gibbs ensemble in isolated integrable quantum\n  systems: The generalized Gibbs ensemble (GGE), which involves multiple conserved\nquantities other than the Hamiltonian, has served as the statistical-mechanical\ndescription of the long-time behavior for several isolated integrable quantum\nsystems. The GGE may involve a noncommutative set of conserved quantities in\nview of the maximum entropy principle, and show that the GGE thus generalized\n(noncommutative GGE, NCGGE) gives a more qualitatively accurate description of\nthe long-time behaviors than that of the conventional GGE. Providing a clear\nunderstanding of why the (NC)GGE well describes the long-time behaviors, we\nconstruct, for noninteracting models, the exact NCGGE that describes the\nlong-time behaviors without an error even at finite system size. It is\nnoteworthy that the NCGGE involves nonlocal conserved quantities, which can be\nnecessary for describing long-time behaviors of local observables. We also give\nsome extensions of the NCGGE and demonstrate how accurately they describe the\nlong-time behaviors of few-body observables.",
        "category": "cond-mat"
    },
    {
        "text": "Pseudofermion ferromagnetism in the Kondo lattices: a mean-field\n  approach: Ground state ferromagnetism of the Kondo lattices is investigated within\nslave fermion approach by Coleman and Andrei within a mean-field approximation\nin the effective hybridization model. Conditions for formation of both\nsaturated (half-metallic) and non-saturated magnetic state are obtained for\nvarious lattices. A description in terms of universal functions which depend\nonly on bare electron density of states (DOS) is presented. A crucial role of\nthe energy dependence of the bare DOS (especially, of DOS peaks) for the\nsmall-moment ferromagnetism formation is demonstrated.",
        "category": "cond-mat"
    },
    {
        "text": "Electron refrigeration in hybrid structures with spin-split\n  superconductors: Electron tunneling between superconductors and normal metals has been used\nfor an efficient refrigeration of electrons in the latter. Such cooling is a\nnon-linear effect and usually requires a large voltage. Here we study the\nelectron cooling in heterostructures based on superconductors with a\nspin-splitting field coupled to normal metals via spin-filtering barriers. The\ncooling power shows a linear term in the applied voltage. This improves the\ncoefficient of performance of electron refrigeration in the normal metal by\nshifting its optimum cooling to lower voltage, and also allows for cooling the\nspin-split superconductor by reverting the sign of the voltage. We also show\nhow tunnel coupling spin-split superconductors with regular ones allows for a\nhighly efficient refrigeration of the latter.",
        "category": "cond-mat"
    },
    {
        "text": "Relaxational dynamics in 3D randomly diluted Ising models: We study the purely relaxational dynamics (model A) at criticality in\nthree-dimensional disordered Ising systems whose static critical behaviour\nbelongs to the randomly diluted Ising universality class. We consider the\nsite-diluted and bond-diluted Ising models, and the +- J Ising model along the\nparamagnetic-ferromagnetic transition line. We perform Monte Carlo simulations\nat the critical point using the Metropolis algorithm and study the dynamic\nbehaviour in equilibrium at various values of the disorder parameter. The\nresults provide a robust evidence of the existence of a unique model-A dynamic\nuniversality class which describes the relaxational critical dynamics in all\nconsidered models. In particular, the analysis of the size-dependence of\nsuitably defined autocorrelation times at the critical point provides the\nestimate z=2.35(2) for the universal dynamic critical exponent. We also study\nthe off-equilibrium relaxational dynamics following a quench from T=\\infty to\nT=T_c. In agreement with the field-theory scenario, the analysis of the\noff-equilibrium dynamic critical behavior gives an estimate of z that is\nperfectly consistent with the equilibrium estimate z=2.35(2).",
        "category": "cond-mat"
    },
    {
        "text": "Quantum critical phenomena of long-range interacting bosons in a\n  time-dependent random potential: We study the superfluid-insulator transition of a particle-hole symmetric\nsystem of long-range interacting bosons in a time-dependent random potential in\ntwo dimensions, using the momentum-shell renormalization-group method. We find\na new stable fixed point with non-zero values of the parameters representing\nthe short- and long-range interactions and disorder when the interaction is\nasymptotically logarithmic. This is contrasted to the non-random case with a\nlogarithmic interaction, where the transition is argued to be first-order, and\nto the $1/r$ Coulomb interaction case, where either a first-order transition or\nan XY-like transition is possible depending on the parameters. We propose that\nour model may be relevant in studying the vortex liquid-vortex glass transition\nof interacting vortex lines in point-disordered type-II superconductors.",
        "category": "cond-mat"
    },
    {
        "text": "Integrable multiparametric quantum spin chains: Using Reshetikhin's construction for multiparametric quantum algebras we\nobtain the associated multiparametric quantum spin chains. We show that under\ncertain restrictions these models can be mapped to quantum spin chains with\ntwisted boundary conditions. We illustrate how this general formalism applies\nto construct multiparametric versions of the supersymmetric t-J and U models.",
        "category": "cond-mat"
    },
    {
        "text": "Modeling Short-Range and Three-Membered Ring Structures in Lithium\n  Borosilicate Glasses using Machine Learning Potential: Lithium borosilicate (LBS) glass is a prototypical lithium-ion conducting\noxide glasses available for an all-solid state buttery. Nevertheless, the\natomistic modeling of LBS glass using $ab$ $initio$ (AIMD) and classical\nmolecular dynamics (CMD) simulations have critical limitations due to\ncomputational cost and inaccuracy in reproducing the glass microstructures,\nrespectively. To overcome these difficulties, a machine-learning potential\n(MLP) was examined in this work for modeling LBS glasses using DeepMD. The\nglass structures obtained by this MLP possessed fourhold-coordinated boron\n($^4$B) confirmed well with the experimental data and abundance of\nthree-membered rings. The models were energetically more stable compared with\nthose constructed with a functional force-field even though both the models\nincluded reasonable $^4$B. The results confirmed MLP to be superior to model\nthe boron-containing glasses and address the inherent shortcomings of the AIMD\nand CMD. This study also discusses some limitations of MLP for modeling\nglasses.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical Properties of an Antiferromagnet near the Quantum Critical\n  Point: Application to LaCuO_2.5: For a system of two-chain spin ladders, the ground state for weak interladder\ncoupling is the spin-liquid state of the isolated ladder, but is an ordered\nantiferromagnet (AF) for sufficiently large interactions. We generalize the\nbond-operator mean-field theory to describe both regimes, and to focus on the\ntransition between them. In the AF phase near the quantum critical point (QCP)\nwe find both spin waves and a low-lying but massive amplitude mode which is\nabsent in a conventional AF. The static susceptibility has the form $\\chi(T) =\n\\chi_0 + a T^2$, with $\\chi_0$ small for a system near criticality. We consider\nthe dynamical properties to examine novel features due to the presence of the\namplitude mode, and compute the dynamic structure factor. LaCuO$_{2.5}$ is\nthought to be such an unconventional AF, whose ordered phase is located very\nclose to the QCP of the transition to the spin liquid. From the N\\'eel\ntemperature we deduce the interladder coupling, the small ordered moment and\nthe gap in the amplitude mode. The dynamical properties unique to near-critical\nAFs are expected to be observable in LaCuO$_{2.5}$.",
        "category": "cond-mat"
    },
    {
        "text": "Halogen in Materials Design: Revealing the Nature of Hydrogen Bonding\n  and Other Non-Covalent Interactions in the Polymorphic Transformations of\n  Methylammonium Lead Tribromide Perovskite: Methylammonium lead tribromide perovskite (CH3NH3PbBr3, or MAPbBr3) as a\nphotovoltaic material has attracted a great deal of recent interest. Factors\nthat are important in their application in optoelectronic devices include their\nfractional contribution of the composition of the materials as well as their\nmicroscopic arrangement that is responsible for the formation of well-defined\nmacroscopic structures. CH3NH3PbBr3 assumes different polymorphs (orthorhombic,\ntetragonal and cubic) depending on the evolution temperature of the bulk\nmaterial. Density functional theory calculations have been performed on\npolymorphs of CH3NH3PbBr3 to demonstrate that the H atoms on C of the methyl\ngroup in MA entrapped within a MAPbBr3 perovskite cage are not electronically\ninnocent, as is often contended. We show here that these H atoms are involved\nin attractive interactions with the surrounding bromides of corner-sharing\noctahedra of the CH3NH3PbBr3 cage to form Br...H(-C) hydrogen bonding\ninteractions. This is analogous to the way the H atoms on N of the ammonium\ngroup in MA form Br...H(-N) hydrogen bonding interactions to stabilize the\nstructure of CH3NH3PbBr3. Both these hydrogen bonding interactions are shown to\npersist regardless of the nature of the three polymorphic forms of CH3NH3PbBr3.\nThese, together with the Br...C(-N) carbon bonding, the Br...N(-C) pnictogen\nbonding, and the Br...Br lump-hole type intermolecular non-covalent\ninteractions identified for the first time in this study, are shown to be\ncollectively responsible for the eventual emergence of the orthorhombic\ngeometry of the CH3NH3PbBr3 system. These conclusions are arrived at from a\nsystematic analysis of the results obtained from combined DFT, Quantum Theory\nof Atoms in Molecules, and Reduced Density Gradient Non-Covalent Interaction\ncalculations carried out on the three temperature-dependent polymorphic\ngeometries of CH3NH3PbBr3.",
        "category": "cond-mat"
    },
    {
        "text": "Application of the finite-temperature Lanczos method for the evaluation\n  of magnetocaloric properties of large magnetic molecules: We discuss the magnetocaloric properties of gadolinium containing magnetic\nmolecules which potentially could be used for sub-Kelvin cooling. We show that\na degeneracy of a singlet ground state could be advantageous in order to\nsupport adiabatic processes to low temperatures and simultaneously minimize\ndisturbing dipolar interactions. Since the Hilbert spaces of such spin systems\nassume very large dimensions we evaluate the necessary thermodynamic\nobservables by means of the Finite-Temperature Lanczos Method.",
        "category": "cond-mat"
    },
    {
        "text": "Optical and electrical properties of Nd3+doped Na2O-ZnO-TeO2 Material: Neodymium doped Na2O-ZnO-TeO2 (NZT) glasses were prepared by the conventional\nmelt quenching technique. DTA and TG were used to confirmation of glass\npreparation through the glass transition temperature at 447{\\deg}C for the\nglass system. The analysis of FTIR spectra and X-ray diffraction described the\nnature of the samples were ionic and amorphous respectively. The optical\nbandgap energy was estimated using absorption spectra and found to be decreased\nfrom 2.63eV to 1.32 eV due to the increase of doping concentration. The\nintensity of the emission spectra was enhanced for the higher concentration of\nNd3+ ions. The dielectric constant of the glass samples was found to be\nconstant for the large range of frequency (3 kHz to 1 MHz). The variation of\nconductivity with the temperature of the samples had shown the Arrhenius\nmechanism of conduction.",
        "category": "cond-mat"
    },
    {
        "text": "Potts model: Duality, Uniformization and the Seiberg-Witten modulus: The introduction of a modulus z(K), analogous to u=<tr phi^2> in the N=2 SUSY\nSU(2) gauge theory solved by Seiberg and Witten, and whose defining property is\nthe invariance under the symmetry and duality transformations of the effective\ncoupling K, reveals an intriguing correspondence between the D=2 Ising and\nPotts models on the square lattice. The moduli spaces of both models, the\nspaces of inequivalent effective temperatures K, correspond to a\nthree-punctured sphere M_3=P^1(C)\\{z=+1,-1,\\infty}. Furthermore, in both\nmodels, the locus of Fisher zeroes is given by the segment joining z_c=-1 to\nz_c=+1.",
        "category": "cond-mat"
    },
    {
        "text": "On the critical weight statistics of the Random Energy Model and of the\n  Directed Polymer on the Cayley Tree: We consider the critical point of two mean-field disordered models : (i) the\nRandom Energy Model (REM), introduced by Derrida as a mean-field spin-glass\nmodel of $N$ spins (ii) the Directed Polymer of length $N$ on a Cayley Tree\n(DPCT) with random bond energies. Both models are known to exhibit a freezing\ntransition between a high temperature phase where the entropy is extensive and\na low-temperature phase of finite entropy. In this paper, we study the weight\nstatistics at criticality via the entropy $S=-\\sum w_i \\ln w_i$ and the\ngeneralized moments $Y_k=\\sum w_i^k$, where the $w_i$ are the Boltzmann weights\nof the $2^N$ configurations. In the REM, we find that the critical weight\nstatistics is governed by the finite-size exponent $\\nu=2$ : the entropy scales\nas $\\bar{S}_N(T_c) \\sim N^{1/2}$, the typical values $e^{\\bar{\\ln Y_k}}$ decay\nas $N^{-k/2}$, and the disorder-averaged values $\\bar{Y_k}$ are governed by\nrare events and decay as $N^{-1/2}$ for any $k>1$. For the DPCT, we find that\nthe entropy scales similarly as $\\bar{S}_N(T_c) \\sim N^{1/2}$, whereas another\nexponent $\\nu'=1$ governs the $Y_k$ statistics : the typical values\n$e^{\\bar{\\ln Y_k}}$ decay as $N^{-k}$, the disorder-averaged values $\\bar{Y_k}$\ndecay as $N^{-1}$ for any $k>1$. As a consequence, the asymptotic probability\ndistribution $\\bar{\\pi}_{N=\\infty}(q)$ of the overlap $q$, beside the delta\nfunction $\\delta(q)$ which bears the whole normalization, contains an isolated\npoint at $q=1$, as a memory of the delta peak $(1-T/T_c) \\delta(q-1)$ of the\nlow-temperature phase $T<T_c$. The associated value $\\bar{\\pi}_{N=\\infty}(q=1)$\nis finite for the DPCT, and diverges as $\\bar{\\pi}_{N=\\infty}(q=1) \\sim\nN^{1/2}$ for the REM.",
        "category": "cond-mat"
    },
    {
        "text": "Electron flow in split-gated bilayer graphene: We present transport measurements on a bilayer graphene sheet with\nhomogeneous back gate and split top gate. The electronic transport data\nindicates the capability to direct electron flow through graphene\nnanostructures purely defined by electrostatic gating. By comparing the\ntransconductance data recorded for different top gate geometries - continuous\nbarrier and split-gate - the observed transport features for the split-gate can\nbe attributed to interference effects inside the narrow opening.",
        "category": "cond-mat"
    },
    {
        "text": "The role of multiplicative noise in critical dynamics: We study the role of multiplicative stochastic processes in the description\nof the dynamics of an order parameter near a critical point. We study\nequilibrium, as well as, out-of-equilibrium properties. By means of a\nfunctional formalism, we built the Dynamical Renormalization Group equations\nfor a real scalar order parameter with $Z_2$ symmetry, driven by a class o\nmultiplicative stochastic processes with the same symmetry. We have computed\nthe flux diagram, using a controlled $\\epsilon$-expansion, up to order\n$\\epsilon^2$. We have found that, for dimensions $d=4-\\epsilon$, the additive\ndynamic fixed point is unstable. The flux runs to a {\\em multiplicative fixed\npoint} driven by a diffusion function $G(\\phi)=1+g^*\\phi^2({\\bf x})/2$, where\n$\\phi$ is the order parameter and $g^*=\\epsilon^2/18$ is the fixed point value\nof the multiplicative noise coupling constant. We show that, even though the\nposition of the fixed point depends on the stochastic prescription, the\ncritical exponents do not. Therefore, different dynamics driven by different\nstochastic prescriptions (such as It\\^o, Stratonovich, anti-It\\^o and so on)\nare in the same universality class.",
        "category": "cond-mat"
    },
    {
        "text": "Anisotropic Gilbert damping in perovskite La$_{0.7}$Sr$_{0.3}$MnO$_{3}$\n  thin film: The viscous Gilbert damping parameter governing magnetization dynamics is of\nprimary importance for various spintronics applications. Although, the damping\nconstant is believed to be anisotropic by theories. It is commonly treated as a\nscalar due to lack of experimental evidence. Here, we present an elaborate\nangle dependent broadband ferromagnetic resonance study of high quality\nepitaxial La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films. Extrinsic effects are suppressed\nand we show convincing evidence of anisotropic damping with twofold symmetry at\nroom temperature. The observed anisotropic relaxation is attributed to the\nmagnetization orientation dependence of the band structure. In addition, we\ndemonstrated that such anisotropy can be tailored by manipulating the stain.\nThis work provides new insights to understand the mechanism of magnetization\nrelaxation.",
        "category": "cond-mat"
    },
    {
        "text": "Kinematically constrained vortex dynamics in charge density waves: We build a minimal model of dissipative vortex dynamics in two spatial\ndimensions, subject to a kinematic constraint: dipole conservation. The\nadditional conservation law implies anomalously slow decay rates for vortices.\nWe argue that this model of vortex dynamics is relevant for a broad range of\ntime scales during a quench into a uniaxial charge density wave state. Our\npredictions are consistent with recent experiments on uniaxial charge density\nwave formation in $\\mathrm{LaTe}_3$.",
        "category": "cond-mat"
    },
    {
        "text": "Spin correlation functions in random-exchange s=1/2 XXZ chains: The decay of (disorder-averaged) static spin correlation functions at T=0 for\nthe one-dimensional spin-1/2 XXZ antiferromagnet with uniform longitudinal\ncoupling $J\\Delta$ and random transverse coupling $J\\lambda_i$ is investigated\nby numerical calculations for ensembles of finite chains. At $\\Delta=0$ (XX\nmodel) the calculation is based on the Jordan-Wigner mapping to free lattice\nfermions for chains with up to N=100 sites. At $\\Delta \\neq 0$ Lanczos\ndiagonalizations are carried out for chains with up to N=22 sites. The\nlongitudinal correlation function $<S_0^z S_r^z>$ is found to exhibit a\npower-law decay with an exponent that varies with $\\Delta$ and, for nonzero\n$\\Delta$, also with the width of the $\\lambda_i$-distribution. The results for\nthe transverse correlation function $<S_0^x S_r^x>$ show a crossover from\npower-law decay to exponential decay as the exchange disorder is turned on.",
        "category": "cond-mat"
    },
    {
        "text": "Electronic and magnetic properties of the 2H-NbS$_2$ intercalated by 3d\n  transition metal atoms: The electronic structure and magnetic properties of the 2H-NbS$_2$ compound\nintercalated by Cr, Mn and Fe, have been investigated by means of the\nKorringa-Kohn-Rostoker (KKR) method. The calculations demonstrate easy plane\nmagneto-crystalline anisotropy (MCA) of Cr$_{1/3}$NbS$_2$ monotonously\ndecreasing towards the Curie temperature in line with the experimental results.\nThe modification of the electronic structure results in a change of the easy\naxis from in-plane to out-of-plane. It is shown, that for Cr$_{1/3}$NbS$_2$ and\nMn$_{1/3}$NbS$_2$ the in-plane MCA and Dzyaloshinskii-Moriya interactions\nresults in a helimagnetic structure along the hexagonal $c$ axis, following the\nexperimental observations. The negative exchange interactions in the\nFe$_{1/3}$NbS$_2$ compound results in a non-collinear frustrated magnetic\nstructure if the MCA is not taken into account. It is shown, however, that a\nstrong MCA along the hexagonal $c$ axis leads to a magnetic ordering referred\nto as an ordering of the third kind, which was observed experimentally.",
        "category": "cond-mat"
    },
    {
        "text": "Rotation of the Trajectories of Bright soliton and Realignment of\n  Intensity Distribution in the Coupled Nonlinear Schrodinger Equation: We revisit the collisional dynamics of bright solitons in the coupled\nNonlinear Schrodinger equation. We observe that apart from the intensity\nredistribution in the interaction of bright solitons, one also witnesses a\nrotation of the trajectories of bright solitons . The angle of rotation can be\nvaried by suitably manipulating the Self-Phase Modulation (SPM) or Cross Phase\nModulation (XPM) parameters.The rotation of the trajectories of the bright\nsolitons arises due to the excess energy that is injected into the dynamical\nsystem through SPM or XPM. This extra energy not only contributes to the\nrotation of the trajectories, but also to the realignment of intensity\ndistribution between the two modes. We also notice that the angular separation\nbetween the bright solitons can also manouvred suitably. The above results\nwhich exclude quantum superposition for the field vectors may have wider\nramifications in nonlinear optics, Bose-Einstein condensates, Left Handed (LH)\nand Right Handed (RH) meta materials.",
        "category": "cond-mat"
    },
    {
        "text": "Loss of control in pattern-directed nucleation: a theoretical study: The properties of template-directed nucleation are studied close to the\ntransition where full nucleation control is lost and additional nucleation\noccurs beyond the pre-patterned regions. First, kinetic Monte Carlo simulations\nare performed to obtain information on a microscopic level. Here the\nexperimentally relevant cases of 1D stripe patterns and 2D square lattice\nsymmetry are considered. The nucleation properties in the transition region\ndepend in a complex way on the parameters of the system, i.e. the flux, the\nsurface diffusion constant, the geometric properties of the pattern and the\ndesorption rate. Second, the properties of the stationary concentration field\nin the fully controlled case are studied to derive the remaining nucleation\nprobability and thus to characterize the loss of nucleation control. Using the\nanalytically accessible solution of a model system with purely radial symmetry,\nsome of the observed properties can be rationalized. A detailed comparison to\nthe Monte Carlo data is included.",
        "category": "cond-mat"
    },
    {
        "text": "Attosecond streaking of core lines of copper dihalides: In the attosecond (as) streaking of Cu 3s core-level photoemission of copper\ndihalides, we predict theoretically that the satellite ($3d^9$) is emitted\nlater than the main line ($3d^{10}L^{-1}$; $L$: ligand). The emission time\ndelay is originated from the electron correlation between the core level and 3d\nshell, which leads to the difference in core-hole screening between satellite\nand main lines. Further, we find that the time delay corresponds to a\nquantification of the extrinsic loss of photoemission.",
        "category": "cond-mat"
    },
    {
        "text": "Properties and Origins of Protein Secondary Structure: Proteins contain a large fraction of regular, repeating conformations, called\nsecondary structure. A simple, generic definition of secondary structure is\npresented which consists of measuring local correlations along the protein\nchain. Using this definition and a simple model for proteins, the forces\ndriving the formation of secondary structure are explored. The relative role of\nenergy and entropy are examined. Recent work has indicated that compaction is\nsufficient to create secondary structure. We test this hypothesis, using simple\nnon-lattice protein models.",
        "category": "cond-mat"
    },
    {
        "text": "ab-plane tilt angles in REBCO conductors: Critical current (Ic) of REBCO tapes is strongly aniso-tropic with respect to\nthe orientation of the magnetic field. Usually, Ic is at maximum when the\nab-plane of the REBCO crystal is parallel to the magnetic field. In commercial\nREBCO tapes, it is commonly assumed that the ab-plane is coincide with the tape\nplane. While in fact, the ab-plane is near but slightly tilted from the tape\nplane in the transverse direction. To accurately measure Ic as a function of\nthe field angle {\\theta} , which is defined as the angle between ab-plane and\nthe magnetic field direction, and to design and fabricate REBCO mag-net coils\nbased on the measured Ic(angle), it is important to measure the tilt angle. In\nthis work, we used x-ray diffraction (XRD) to measure the tilt angles at room\ntemperature for a large number of REBCO conductors made by SuperPower Inc.\nTransmission electron mi-croscopy (TEM) was also used to investigate the origin\nof this tilt. The measured data are presented, and the measurement uncer-tainty\nis discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Quantitative analysis of Sr2RuO4 ARPES spectra: Many-body interactions\n  in a model Fermi liquid: ARPES spectra hold a wealth of information about the many-body interactions\nin a correlated material. However, the quantitative analysis of ARPES spectra\nto extract the various coupling parameters in a consistent manner is extremely\nchallenging, even for a model Fermi liquid system. We propose a fitting\nprocedure which allows quantitative access to the intrinsic lineshape,\ndeconvolved of energy and momentum resolution effects, of the correlated\n2-dimensional material Sr2RuO4. For the first time in correlated 2-dimensional\nmaterials, we find an ARPES linewidth that is narrower than its binding energy,\na key property of quasiparticles within Fermi liquid theory. We also find that\nwhen the electron-electron scattering component is separated from the\nelectron-phonon and impurity scattering terms it decreases with a functional\nform compatible with Fermi liquid theory as the Fermi energy is approached. In\ncombination with the previously determined Fermi surface, these results give\nthe first complete picture of a Fermi liquid system via ARPES. Furthermore, we\nshow that the magnitude of the extracted imaginary part of the self-energy is\nin remarkable agreement with DC transport measurements.",
        "category": "cond-mat"
    },
    {
        "text": "Different ways of dealing with Compton scattering and positron\n  annihilation experimental data: Different ways of dealing with one-dimensional (1D) spectra, measured e.g. in\nthe Compton scattering or angular correlation of positron annihilation\nradiation (ACAR) experiments are presented. On the example of divalent\nhexagonal close packed metals it is shown what kind of information on the\nelectronic structure one can get from 1D profiles, interpreted in terms of\neither 2D or 3D momentum densities. 2D and 3D densities are reconstructed from\nmerely two and seven 1D profiles, respectively. Applied reconstruction\ntechniques are particular solutions of the Radon transform in terms of\northogonal Gegenabauer polynomials. We propose their modification connected\nwith so-called two-step reconstruction. The analysis is performed both in the\nextended p and reduced k zone schemes. It is demonstrated that if positron wave\nfunction or many-body effects are strongly momentum dependent, analysis of 2D\ndensities folded into k space may lead to wrong conclusions concerning the\nFermi surface. In the case of 2D ACAR data in Mg we found very strong many-body\neffects. PACS numbers: 71.18.+y, 13.60.Fz, 87.59.Fm",
        "category": "cond-mat"
    },
    {
        "text": "Thermally driven ballistic rectifer: The response of electric devices to an applied thermal gradient has, so far,\nbeen studied almost exclusively in two-terminal devices. Here we present\nmeasurements of the response to a thermal bias of a four-terminal,\nquasi-ballistic junction with a central scattering site. We find a novel\ntransverse thermovoltage measured across isothermal contacts. Using a\nmulti-terminal scattering model extended to the weakly non-linear voltage\nregime, we show that the device's response to a thermal bias can be predicted\nfrom its nonlinear response to an electric bias. Our approach forms a\nfoundation for the discovery and understanding of advanced, nonlocal,\nthermoelectric phenomena that in the future may lead to novel thermoelectric\ndevice concepts.",
        "category": "cond-mat"
    },
    {
        "text": "Prediction of anomalous LA-TA splitting in electrides: Electrides are an emerging class of materials with excess electrons localized\nin interstices and acting as anionic interstitial quasi-atoms (ISQs). The\nspatial ion-electron separation means that electrides can be treated physically\nas ionic crystals, and this unusual behavior leads to extraordinary physical\nand chemical phenomena. Here, a completely different effect in electrides is\npredicted. By recognizing the long-range Coulomb interactions between matrix\natoms and ISQs that are unique in electrides, a nonanalytic correction to the\nforces exerted on matrix atoms is proposed. This correction gives rise to an\nLA-TA splitting in the acoustic branch of lattice phonons near the zone center,\nsimilar to the well-known LO-TO splitting in the phonon spectra of ionic\ncompounds. The factors that govern this splitting are investigated, with\nisotropic fcc-Li and anisotropic hP4-Na as the typical examples. It is found\nthat not all electrides can induce a detectable splitting, and criteria are\ngiven for this type of splitting. The present prediction unveils the rich\nphenomena in electrides and could lead to unprecedented applications.",
        "category": "cond-mat"
    },
    {
        "text": "van der Waals-like phase separation instability of a driven granular gas\n  in three dimensions: We show that the van der Waals-like phase separation instability of a driven\ngranular gas at zero gravity, previously investigated in two-dimensional\nsettings, persists in three dimensions. We consider a monodisperse granular gas\ndriven by a thermal wall of a three-dimensional rectangular container at zero\ngravity. The basic steady state of this system, as described by granular\nhydrodynamic equations, involves a denser and colder layer of granulate located\nat the wall opposite to the driving wall. When the inelastic energy loss is\nsufficiently high, the driven granular gas exhibits, in some range of average\ndensities, negative compressibility in the directions parallel to the driving\nwall. When the lateral dimensions of the container are sufficiently large, the\nnegative compressibility causes spontaneous symmetry breaking of the basic\nsteady state and a phase separation instability. Event-driven molecular\ndynamics simulations confirm and complement our theoretical predictions.",
        "category": "cond-mat"
    },
    {
        "text": "Transport in Fermi Liquids Confined by Rough Walls: I present theoretical calculations of the thermal conductivity of Fermi\nliquid 3He confined to a slab of thickness of order 100nm. The effect of the\nroughness of the confining surfaces is included directly in terms of the\nsurface roughness power spectrum which may be determined experimentally.\nTransport at low temperatures is limited by scattering off rough surfaces and\nevolves into the known high-temperature limit in bulk through an anomalous\nregime in which both inelastic quasiparticle scattering and elastic scattering\noff the rough surface coexist. I show preliminary calculations for the\ncoefficients of thermal conductivity. These studies are applicable in the\ncontext of electrical transport in metal nanowires as well as experiments that\nprobe the superfluid phase diagram of liquid 3He in a slab geometry.",
        "category": "cond-mat"
    },
    {
        "text": "Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron\n  Pnictides: Using first-principle density functional theory calculations combined with\ninsight from a tight-binding representation, dynamical mean field theory, and\nlinear response theory, we have extensively investigated the electronic\nstructures and magnetic interactions of nine ferropnictides representing three\ndifferent structural classes. The calculated magnetic interactions are found to\nbe short-range, and the nearest ($J_{1a}$) and next-nearest ($J_{2}$) exchange\nconstants follow the universal trend of J_{1a}/2J_{2}\\sim 1, despite their\nitinerant origin and extreme sensitivity to the z-position of As. These results\nbear on the discussion of itineracy versus magnetic frustration as the key\nfactor in stabilizing the superconducting ground state. The calculated spin\nwave dispersions show strong magnetic anisotropy in the Fe plane, in contrast\nto cuprates.",
        "category": "cond-mat"
    },
    {
        "text": "Intrinsic origin of electron scattering at 4H-SiC(0001)/SiO$_2$: We introduce a first-principles study to clarify the carrier-scattering\nproperty at the SiC/SiO$_2$. Interestingly, the electron transport at the\nconduction-band edge is significantly affected by the introduction of oxygen,\neven though there are no electrically active defects. The origin of the large\nscattering is explained by the behavior of the internal-space states (ISSs).\nMoreover, the effect of the ISSs is larger than that of the electrically active\ncarbon-related defects. This result indicates that an additional scattering not\nconsidered in a conventional Si/SiO$_2$ occurs at the SiC/SiO$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Ion specificity and the theory of stability of colloidal suspensions: A theory is presented which allow us to accurately calculate the critical\ncoagulation concentration (CCC) of hydrophobic colloidal suspensions. For\npositively charged particles the CCC's follow the Hofmeister (lyotropic)\nseries. For negatively charged particles the series is reversed. We find that\nstrongly polarizable chaotropic anions are driven towards the colloidal surface\nby electrostatic and hydrophobic forces. Within approximately one ionic radius\nfrom the surface, the chaotropic anions loose part of their hydration sheath\nand become strongly adsorbed. The kosmotropic anions, on the other hand, are\nrepelled from the hydrophobic surface. The theory is quantitatively accurate\nwithout any adjustable parameters. We speculate that the same mechanism is\nresponsible for the Hofmeister series that governs stability of protein\nsolutions.",
        "category": "cond-mat"
    },
    {
        "text": "Low-temperature structural transition in FeCr_2S_4: Transmission electron microscopy studies of [110] and [111] oriented\nFeCr_2S_4 single crystals at different temperatures reveal a structural\ntransition at low temperatures indicating a cubic-to-triclinic symmetry\nreduction within crystallographic domains. The overall crystal symmetry was\nfound to be reduced from Fd3m to F-43m. The triclinic distortions were\nsuggested to result from the combined actions of tetragonal distortions due to\nthe Jahn-Teller active Fe^2+ ions and trigonal distortions due to a\ndisplacement of the Cr^3+ ions in the <111> direction.",
        "category": "cond-mat"
    },
    {
        "text": "Binding a Hopfion in Chiral Magnet Nanodisk: Hopfions are three-dimensional (3D) topological textures characterized by the\ninteger Hopf invariant $Q_H$. Here, we present the realization of a\nzero--field, stable hopfion spin texture in a magnetic system consisting of a\nchiral magnet nanodisk sandwiched by two films with perpendicular magnetic\nanisotropy. The preimages of the spin texture and numerical calculations of\n$Q_H$ show that the hopfion has $Q_H=1$. Furthermore, another non-trivial state\nthat includes a monopole--antimonopole pair (MAP) is also stabilized in this\nsystem. By applying an external magnetic field, hopfion and MAP states with the\nsame polarization can be switched between each other. The topological\ntransition between the hopfion and the MAP state involves a creation\n(annihilation) of the MAP and twist of the preimages. Our work paves the way to\nstudy non-trivial 3D topological spin textures and stimulates more\ninvestigations in the field of 3D spintronics.",
        "category": "cond-mat"
    },
    {
        "text": "Large Scale (~25 m^2) metal diffraction grating of submicron period as\n  possible optoelectronic detector for short scalar gravitational waves: A method of detecting of short scalar gravitational waves with a wavelength\nof ~ 0.5 micrometers is proposed, in contrast to LIGO Project, aimed at\ndetecting of long quadrupole gravitational waves with a wavelength in interval\nfrom 43 till 10000 km. The conduction electrons in a metal are proposed to use\nas gravitational receiving antennas (pendulums) instead of massive mirrors in\nLIGO. It is shown that using a Large Scale metal diffraction grating with area\nof 25 m^2 you can convert the mechanical vibrations of the conduction electrons\nof metal into a plane electromagnetic wave propagating along the normal to the\ngrating. It is shown that when the amplitude of the scalar gravitational wave\nin a source (in quasar at the centre of our galaxy) is greater than Ag0 = 10^20\ncm/(s^2), you can register it with the help of a large optical telescope\nequipped with the proposed diffraction grating. It is shown that the special\ntheory of relativity allows the amplitude of the scalar gravitational waves in\nthis source by 5 orders of magnitude greater than the above-mentioned minimum\nvalue.",
        "category": "cond-mat"
    },
    {
        "text": "Memory of jamming - multiscale models for soft and granular matter: Soft, disordered, micro-structured materials are ubiquitous in nature and\nindustry, and are different from ordinary fluids or solids, with unusual,\ninteresting static and flow properties. The transition from fluid to solid -at\nthe so-called jamming density- features a multitude of complex mechanisms, but\nthere is no unified theoretical framework that explains them all. In this\nstudy, a simple yet quantitative and predictive model is presented, which\nallows for a variable, changing jamming density, encompassing the memory of the\ndeformation history and explaining a multitude of phenomena at and around\njamming. The jamming density, now introduced as a new state-variable, changes\ndue to the deformation history and relates the system's macroscopic response to\nits microstructure. The packing efficiency can increase logarithmically slow\nunder gentle repeated (isotropic) compression, leading to an increase of the\njamming density. In contrast, shear deformations cause anisotropy, changing the\npacking efficiency exponentially fast with either dilatancy or compactancy. The\nmemory of the system near jamming can be explained by a microstatistical model\nthat involves a multiscale, fractal energy landscape and links the microscopic\nparticle picture to the macroscopic continuum description, providing a unified\nexplanation for the qualitatively different flow-behavior for different\ndeformation modes. To complement our work, a recipe to extract the\nhistory-dependent jamming density from experimentally accessible data is\nproposed, and alternative state-variables are compared. The proposed simple\nmacroscopic constitutive model is calibrated with the memory of microstructure.\nSuch approach can help understanding predicting and mitigating failure of\nstructures or geophysical hazards, and will bring forward industrial process\ndesign/optimization, and help solving scientific challenges in fundamental\nresearch.",
        "category": "cond-mat"
    },
    {
        "text": "Giant energy oscillations mediated by a quasiperiodically driven qubit: A qubit driven by two incommensurate frequencies can mediate a quantised\naverage energy current in the adiabatic limit. We show that non-adiabatic\nprocesses result in reversals of the energy current and corresponding\noscillations in the net energy transferred between the drives. The oscillations\nare bounded but giant -- much larger than the qubit energy splitting. A\nLandau-Zener analysis predicts that the timescale of the oscillations is\nexponentially large in the period of the drives. However, numerical analysis\nreveals that this timescale is not a monotonic function of the period, and has\nincreasing sub-structure as the adiabatic limit is approached. We show that\nthis non-monotonicity arises from interference effects between subsequent\nLandau-Zener transitions. Giant energy oscillations should be observable in\nnear-term experiments with nitrogen-vacancy centers.",
        "category": "cond-mat"
    },
    {
        "text": "Entropy production rate of nonequilibrium systems from the Fokker-Planck\n  equation: The entropy production rate of nonequilibrium systems is studied via the\nFokker-Planck equation. This approach, based on the entropy production rate\nequation given by Schnakenberg from a master equation, requires information of\nthe transition rate of the system under study. We obtain the transition rate\nfrom the conditional probability extracted from the Fokker-Planck equation and\nthen derive a new and more operable expression for the entropy production rate.\nExamples are presented as applications of our approach.",
        "category": "cond-mat"
    },
    {
        "text": "Competing magnetic orders in a bilayer Hubbard model with ultracold\n  atoms: Fermionic atoms in optical lattices have served as a compelling model system\nto study and emulate the physics of strongly-correlated matter. Driven by the\nadvances of high-resolution microscopy, the recent focus of research has been\non two-dimensional systems in which several quantum phases, such as\nanti-ferromagnetic Mott insulators for repulsive interactions and\ncharge-density waves for attractive interactions have been observed. However,\nthe aspired emulations of real materials, such as bilayer graphene, have to\ntake into account that their lattice structure composes of coupled layers and\ntherefore is not strictly two-dimensional. In this work, we realize a bilayer\nFermi-Hubbard model using ultracold atoms in an optical lattice and demonstrate\nthat the interlayer coupling controls a crossover between a planar\nanti-ferromagnetically ordered Mott insulator and a band insulator of\nspin-singlets along the bonds between the layers. Our work will enable the\nexploration of further fascinating properties of coupled-layer Hubbard models,\nsuch as theoretically predicted superconducting pairing mechanisms.",
        "category": "cond-mat"
    },
    {
        "text": "Equilibrium and Kinetics: Water Confined in Carbon Nanotube as 1D\n  Lattice Gas: A simple 1D lattice gas model is presented, which very well describes the\nequilibrium and kinetic behaviors of water confined in a thin carbon nanotube\nfound in an atomistic molecular dynamics(MD) simulation {[} Nature {\\bf 414},\n188 (2001) {]}. The model parameters are corresponding to various physical\ninteractions and can be calculated or estimated in statistic mechanics. The\nroles of every interaction in the water filling, emptying and transporting\nprocesses are clearly understood. Our results indicate that the physical\npicture of the single-file kinetics is very simple.",
        "category": "cond-mat"
    },
    {
        "text": "Phase diagram of the quarter-filled extended Hubbard model on a two-leg\n  ladder: We investigate the ground-state phase diagram of the quarter-filled Hubbard\nladder with nearest-neighbor Coulomb repulsion V using the Density Matrix\nRenormalization Group technique. The ground-state is homogeneous at small V, a\n``checkerboard'' charge--ordered insulator at large V and not too small on-site\nCoulomb repulsion U, and is phase-separated for moderate or large V and small\nU. The zero-temperature transition between the homogeneous and the\ncharge-ordered phase is found to be second order. In both the homogeneous and\nthe charge-ordered phases the existence of a spin gap mainly depends on the\nratio of interchain to intrachain hopping. In the second part of the paper, we\nconstruct an effective Hamiltonian for the spin degrees of freedom in the\nstrong-coupling charge-ordered regime which maps the system onto a frustrated\nspin chain. The opening of a spin gap is thus connected with spontaneous\ndimerization.",
        "category": "cond-mat"
    },
    {
        "text": "Characterizing fractional topological phases of lattice bosons near the\n  first Mott lobe: The Bose-Hubbard model subjected to an effective magnetic field hosts a\nplethora of phases with different topological orders when tuning the chemical\npotential. Using the density matrix renormalization group method, we identify\nseveral gapped phases near the first Mott lobe at strong interactions. They are\nconnected by a particle-hole symmetry to a variety of quantum Hall states\nstabilized at low fillings. We characterize phases of both particle and hole\ntype and identify signatures compatible with Laughlin, Moore-Read, and Bosonic\nInteger Quantum Hall states by calculating the quantized Hall conductance and\nby extracting the topological entanglement entropy. Furthermore, we analyze the\nentanglement spectrum of a Laughlin state of bosonic particles and holes for a\nrange of interaction strengths, as well as the entanglement spectrum of a\nMoore-Read state. These results further corroborate the existence of\ntopological states at high fillings, close to the first Mott lobe, as hole\nanalogues of the respective low-filling states.",
        "category": "cond-mat"
    },
    {
        "text": "Ferroelectricity from iron valence ordering in rare earth ferrites?: The possibility of multiferroicity arising from charge ordering in LuFe2O4\nand structurally related rare earth ferrites is reviewed. Recent experimental\nwork on macroscopic indications of ferroelectricity and microscopic\ndetermination of coupled spin and charge order indicates that this scenario\ndoes not hold. Understanding the origin of the experimentally observed charge\nand spin order will require further theoretical work. Other aspects of recent\nresearch in these materials, such as geometrical frustration effects, possible\nelectric-field-induced transitions, or orbital order are also briefly treated.",
        "category": "cond-mat"
    },
    {
        "text": "The Nature of Electron Transport and visible light absorption in\n  Strontium Niobate -- A Plasmonic Water Splitter: Semiconductor compounds are widely used for water splitting applications,\nwhere photo-generated electron-hole pairs are exploited to induce catalysis.\nRecently, powders of a metallic oxide (Sr$_{1-x}$NbO$_3$, 0.03 < x < 0.20) have\nshown competitive photocatalytic efficiency, opening up the material space\navailable for finding optimizing performance in water-splitting applications.\nThe origin of the visible light absorption in these powders was reported to be\ndue to an interband transition and the charge carrier separation was proposed\nto be due to the high carrier mobility of this material. In the current work we\nhave prepared epitaxial thin films of Sr$_{0.94}$NbO$_{3+{\\delta}}$ and found\nthat the bandgap of this material is ~4.1 eV, which is very large. Surprisingly\nthe carrier density of the conducting phase reaches 10$^{22}$ cm$^{-3}$, which\nis only one order smaller than that of elemental metals and the carrier\nmobility is only 2.47 cm$^2$/(V$\\cdot$s). Contrary to earlier reports, the\nvisible light absorption at 1.8 eV (~688 nm) is due to the bulk plasmon\nresonance, arising from the large carrier density, instead of an interband\ntransition. Excitation of the plasmonic resonance results in a multifold\nenhancement of the lifetime of charge carriers. Thus we propose that the hot\ncharge carriers generated from decay of plasmons produced by optical absorption\nis responsible for the water splitting efficiency of this material under\nvisible light irradiation.",
        "category": "cond-mat"
    },
    {
        "text": "Influence of heat flow directions on Nernst effects in Py/Pt bilayers: We investigated the voltages obtained in a thin Pt strip on a Permalloy film\nwhich was subject to in-plane temperature gradients and magnetic fields. The\nvoltages detected by thin W-tips or bond wires showed a purely symmetric effect\nwith respect to the external magnetic field which can be fully explained by the\nplanar Nernst effect (PNE). To verify the influence of the contacts\nmeasurements in vacuum and atmosphere were compared and gave similar results.\nWe explain that a slightly in-plane tilted temperature gradient only shifts the\nfield direction dependence but does not cancel out the observed effects.\nAdditionally, the anomalous Nernst effect (ANE) could be induced by using thick\nAu-tips which generated a heat current perpendicular to the sample plane. The\neffect can be manipulated by varying the temperature of the Au-tips. These\nmeasurements are discussed concerning their relevance in transverse spin\nSeebeck effect measurements.",
        "category": "cond-mat"
    },
    {
        "text": "Fractional Brownian motion and the critical dynamics of zipping polymers: We consider two complementary polymer strands of length $L$ attached by a\ncommon end monomer. The two strands bind through complementary monomers and at\nlow temperatures form a double stranded conformation (zipping), while at high\ntemperature they dissociate (unzipping). This is a simple model of DNA (or RNA)\nhairpin formation. Here we investigate the dynamics of the strands at the\nequilibrium critical temperature $T=T_c$ using Monte Carlo Rouse dynamics. We\nfind that the dynamics is anomalous, with a characteristic time scaling as\n$\\tau \\sim L^{2.26(2)}$, exceeding the Rouse time $\\sim L^{2.18}$. We\ninvestigate the probability distribution function, the velocity autocorrelation\nfunction, the survival probability and boundary behaviour of the underlying\nstochastic process. These quantities scale as expected from a fractional\nBrownian motion with a Hurst exponent $H=0.44(1)$. We discuss similarities and\ndifferences with unbiased polymer translocation.",
        "category": "cond-mat"
    },
    {
        "text": "Role of disorder in determining the vibrational properties of\n  mass-spring networks: By introducing four fundamental types of disorders into a two-dimensional\ntriangular lattice separately, we determine the role of each type of disorder\nin the vibration of the resulting mass-spring networks. We are concerned mainly\nwith the origin of the boson peak and the connection between the boson peak and\nthe transverse Ioffe-Regel limit. For all types of disorders, we observe the\nemergence of the boson peak and Ioffe-Regel limits. With increasing disorder,\nthe boson peak frequency $\\omega_{BP}$, transverse Ioffe-Regel frequency\n$\\omega_{IR}^T$, and longitudinal Ioffe-Regel frequency $\\omega_{IR}^L$ all\ndecrease. We find that there are two ways for the boson peak to form:\ndeveloping from and coexisting with (but remaining independent of) the\ntransverse van Hove singularity without and with local coordination number\nfluctuation. In the presence of a single type of disorder, $\\omega_{IR}^T\\ge\n\\omega_{BP}$, and $\\omega_{IR}^T\\approx \\omega_{BP}$ only when the disorder is\nsufficiently strong and causes spatial fluctuation of the local coordination\nnumber. Moreover, if there is no positional disorder, $\\omega_{IR}^T\\approx\n\\omega_{IR}^L$. Therefore, the argument that the boson peak is equivalent to\nthe transverse Ioffe-Regel limit is not general. Our results suggest that both\nlocal coordination number and positional disorder are necessary for the\nargument to hold, which is actually the case for most disordered solids such as\nmarginally jammed solids and structural glasses. We further combine two types\nof disorders to cause disorder in both the local coordination number and\nlattice site position. The density of vibrational states of the resulting\nnetworks resembles that of marginally jammed solids well. However, the relation\nbetween the boson peak and the transverse Ioffe-Regel limit is still indefinite\nand condition-dependent.",
        "category": "cond-mat"
    },
    {
        "text": "Thermal radiation as a probe of one-dimensional electron liquids: Motivated by recent developments in the field of plasmonics, we develop the\ntheory of radiation from one-dimensional electron liquids, showing that the\nspectrum of thermal radiation emitted from the system exhibits signatures of\nnon-Fermi liquid behavior. We derive a multipole expansion for the radiation\nbased on the Tomonaga-Luttinger liquid model. While the dipole radiation\npattern is determined by the conductivity of the system, we demonstrate that\nthe quadrupole radiation can reveal important features of the quantum liquid,\nsuch as the Luttinger parameter. Radiation offers a probe of the interactions\nof the system, including Mott physics as well as non-linear Luttinger liquid\nbehavior. We show that these effects can be probed in current experiments on\neffectively one-dimensional electron liquids, such as carbon nanotubes.",
        "category": "cond-mat"
    },
    {
        "text": "Phase Diagram of a Loop on the Square Lattice: The phase diagram of the O(n) model, in particular the special case $n=0$, is\nstudied by means of transfer-matrix calculations on the loop representation of\nthe O(n) model. The model is defined on the square lattice; the loops are\nallowed to collide at the lattice vertices, but not to intersect. The loop\nmodel contains three variable parameters that determine the loop density or\ntemperature, the energy of a bend in a loop, and the interaction energy of\ncolliding loop segments. A finite-size analysis of the transfer-matrix results\nyields the phase diagram in a special plane of the parameter space. These\nresults confirm the existence of a multicritical point and an Ising-like\ncritical line in the low-temperature O(n) phase.",
        "category": "cond-mat"
    },
    {
        "text": "Electronic structures of ferromagnetic superconductors $\\mathrm{UGe}_2$\n  and $\\mathrm{UCoGe}$ studied by angle-resolved photoelectron spectroscopy: The electronic structures of the ferromagnetic superconductors\n$\\mathrm{UGe}_2$ and $\\mathrm{UCoGe}$ in the paramagnetic phase were studied by\nangle-resolved photoelectron spectroscopy using soft X-rays ($h\\nu =400-500$).\nThe quasi-particle bands with large contributions from $\\mathrm{U}~5f$ states\nwere observed in the vicinity of $E_\\mathrm{F}$, suggesting that the\n$\\mathrm{U}~5f$ electrons of these compounds have an itinerant character. Their\noverall band structures were explained by the band-structure calculations\ntreating all the $\\mathrm{U}~5f$ electrons as being itinerant. Meanwhile, the\nstates in the vicinity of $E_\\mathrm{F}$ show considerable deviations from the\nresults of band-structure calculations, suggesting that the shapes of Fermi\nsurface of these compounds are qualitatively different from the calculations,\npossibly caused by electron correlation effect in the complicated band\nstructures of the low-symmetry crystals. Strong hybridization between\n$\\mathrm{U}~5f$ and $\\mathrm{Co}~3d$ states in $\\mathrm{UCoGe}$ were found by\nthe $\\mathrm{Co}~2p-3d$ resonant photoemission experiment, suggesting that\n$\\mathrm{Co}~3d$ states have finite contributions to the magnetic, transport,\nand superconducting properties.",
        "category": "cond-mat"
    },
    {
        "text": "Random walks on weighted networks: Exploring local and non-local\n  navigation strategies: In this paper, we present an overview of different types of random walk\nstrategies with local and non-local transitions on undirected connected\nnetworks. We present a general approach to analyzing these strategies by\ndefining the dynamics as a discrete time Markovian process with probabilities\nof transition expressed in terms of a symmetric matrix of weights. In the first\npart, we describe the matrices of weights that define local random walk\nstrategies like the normal random walk, biased random walks, random walks in\nthe context of digital image processing and maximum entropy random walks. In\naddition, we explore non-local random walks like L\\'evy flights on networks,\nfractional transport and applications in the context of human mobility.\nExplicit relations for the stationary probability distribution, the mean first\npassage time and global times to characterize the random walk strategies are\nobtained in terms of the elements of the matrix of weights and its respective\neigenvalues and eigenvectors. Finally, we apply the results to the analysis of\nparticular local and non-local random walk strategies; we discuss their\nefficiency and capacity to explore different types of structures. Our results\nallow to study and compare on the same basis the global dynamics of different\ntypes of random walk strategies.",
        "category": "cond-mat"
    },
    {
        "text": "Interband coherence induced correction to Thouless pumping: possible\n  observation in cold-atom systems: In Thouless pump, the charge transport in a one-dimensional insulator over an\nadiabatic cycle is topologically quantized. For nonequilibrium initial states,\nhowever, interband coherence will induce a previously unknown contribution to\nThouless pumping. Though not geometric in nature, this contribution is\nindependent of the time scale of the pumping protocol. In this work, we perform\na detailed analysis of our previous finding [Phys. Rev. B 91, 085420 (2015)] in\nan already available cold-atom setup. We show that initial states with\ninterband coherence can be obtained via a quench of the system's Hamiltonian.\nAdiabatic pumping in the post-quench system are then examined both\ntheoretically and numerically, in which the interband coherence is shown to\nplay an important role and can hence be observed experimentally. By choosing\nadiabatic protocols with different switching-on speeds, we also show that the\ncontribution of interband coherence to adiabatic pumping can be tuned. It is\nfurther proposed that the interband coherence induced correction to Thouless\npumping may be useful in capturing a topological phase transition point. All\nour results have direct experimental interests.",
        "category": "cond-mat"
    },
    {
        "text": "Evolution of ferromagnetic order in URhGe alloyed with Ru, Co and Si: We have investigated the evolution of ferromagnetic order in the correlated\nmetal URhGe (Curie temperature $T_{\\rm C} = $9.5 K) by chemical substitution of\nRu, Co and Si. Polycrystalline samples URh$_{1-x}$Ru$_x$Ge ($x \\leq $0.6),\nURh$_{1-x}$Co$_x$Ge ($x \\leq $0.9) and URhGe$_{1-x}$Si$_x$ ($x \\leq $0.2) have\nbeen prepared and the magnetic properties have been investigated by\nmagnetization and transport experiments. In the case of Ru doping, $T_{\\rm C}$\ninitially increases, but then decreases linearly as a function of $x$ and is\ncompletely suppressed for $x_{\\rm cr} \\approx 0.38$. The Curie temperature in\nthe URh$_{1-x}$Co$_x$Ge series has a broad maximum $T_{\\rm C} = 20$ K near\n$x=0.6$ and then drops to 8 K for $x=0.9$. In the case of Si doping $T_{\\rm C}$\nstays roughly constant. We conclude that the alloy systems URh$_{1-x}$Ru$_x$Ge\nand URh$_{1-x}$Co$_x$Ge are interesting candidates to study the ferromagnetic\ninstability.",
        "category": "cond-mat"
    },
    {
        "text": "Imaging Grains and Grain Boundaries in Single-Layer Graphene: An Atomic\n  Patchwork Quilt: The properties of polycrystalline materials are often dominated by the size\nof their grains and by the atomic structure of their grain boundaries. These\neffects should be especially pronounced in 2D materials, where even a line\ndefect can divide and disrupt a crystal. These issues take on practical\nsignificance in graphene, a hexagonal two-dimensional crystal of carbon atoms;\nSingle-atom-thick graphene sheets can now be produced by chemical vapor\ndeposition on up to meter scales, making their polycrystallinity almost\nunavoidable. Theoretically, graphene grain boundaries are predicted to have\ndistinct electronic, magnetic, chemical, and mechanical properties which\nstrongly depend on their atomic arrangement. Yet, because of the\nfive-order-of-magnitude size difference between grains and the atoms at grain\nboundaries, few experiments have fully explored the graphene grain structure.\nHere, we use a combination of old and new transmission electron microscope\ntechniques to bridge these length scales. Using atomic-resolution imaging, we\ndetermine the location and identity of every atom at a grain boundary and find\nthat different grains stitch together predominantly via pentagon-heptagon\npairs. We then use diffraction-filtered imaging to rapidly map the location,\norientation, and shape of several hundred grains and boundaries, where only a\nhandful have been previously reported. The resulting images reveal an\nunexpectedly small and intricate patchwork of grains connected by tilt\nboundaries. By correlating grain imaging with scanned probe measurements, we\nshow that these grain boundaries dramatically weaken the mechanical strength of\ngraphene membranes, but do not measurably alter their electrical properties.\nThese techniques open a new window for studies on the structure, properties,\nand control of grains and grain boundaries in graphene and other 2D materials.",
        "category": "cond-mat"
    },
    {
        "text": "Controlling grain boundaries by magnetic fields: The ability to use external magnetic fields to influence the microstructure\nin polycrystalline materials has potential applications in microstructural\nengineering. To explore this potential and to understand the complex\ninteractions between electromagnetic fields and solid-state matter transport we\nconsider a phase-field-crystal (PFC) model. Together with efficient and\nscalable numerical algorithms this allows the examination of the role that\nexternal magnetic fields play on the evolution of defect structures and grain\nboundaries, on diffusive time scales. Examples for planar and circular grain\nboundaries explain the essential atomistic processes and large scale\nsimulations in 2D are used to obtain statistical data on grain growth under the\ninfluence of external fields.",
        "category": "cond-mat"
    },
    {
        "text": "Criterion for weak spin-orbit coupling in heavy-fermion\n  superconductivity: A numerical renormalization-group study: A criterion for effective irrelevancy of the spin-orbit coupling in the\nheavy-fermion superconductivity is discussed on the basis of the impurity\nAnderson model with two sets of Kramers doublets. Using Wilson's numerical\nrenormalization-group method, we demonstrate a formation of the quasiparticle\nas well as the renormalization of the rotational symmetry-breaking interaction\nin the lower Kramers doublet (quasispin) space. A comparison with the quasispin\nconserving interaction exhibits the effective irrelevancy of the\nsymmetry-breaking interaction for the splitting of two doublets Delta larger\nthan the characteristic energy of the local spin fluctuation T_K. The formula\nfor the ratio of two interactions is also determined.",
        "category": "cond-mat"
    },
    {
        "text": "Understanding one-dimensional topological Kondo insulator: Poor man's\n  non-uniform antiferromagnetic mean-field theory versus quantum Monte Carlo\n  simulation: Topological Kondo insulator (TKI) is an essential example of interacting\ntopological insulator, where electron's correlation effect plays a key role.\nHowever, most of our understanding on this timely issue comes from numerical\nsimulations, (particularly in one-spatial dimension) which exactly includes\ncorrelation effect but is black box for extracting underlying physics. In this\nwork, we use a non-uniform antiferromagnetic mean-field (nAFM) theory to\nunderstand the underlying physics in a TKI model, the $1D$ $p-$wave periodic\nAnderson model ($p$-PAM). Comparing with numerically exact quantum Monte Carlo\nsimulation, we find that nAFM theory is an excellent approximation for\nground-state properties when onsite Hubbard interaction is weak. This\nemphasizes the dominating antiferromagnetic correlation in this system and\nlocal antiferromagnetic picture captures the qualitative nature of interacting\nmany-body ground state. Adding extra conduction electron band to $p$-PAM leads\nto a quantum phase transition from Haldane phase into topological trivial\nphase. We believe these results may be helpful for understanding novel physics\nin interacting TKI materials such as SmB$_{6}$ and other related compounds.",
        "category": "cond-mat"
    },
    {
        "text": "Superconducting junction with tri-component pairing gap functions: We study a superconducting hetro-junction with one side characterized by the\nunconventional chiral $p$-wave gap function $p_x\\pm ip_y$ and the other side\nthe conventional $s$-wave one. Though a relative phase of $\\pm \\frac{\\pi}{2}$\nbetween any two components of gap functions is favored in the junction region,\nmutual phase differences cannot achieve $\\pm \\frac{\\pi}{2}$ simultaneously,\nwhich results in frustration. Based on a Ginzburg-Landau free energy analysis,\nthe frustrated pattern is determined to be $s+ i\\eta_1 (e^{ i\\eta_2\n\\varphi/2}p_x +\\eta_3 e^{- i\\eta_2 \\varphi/2}p_y)$ with $\\eta_j=\\pm 1$\n($j=1,2,3$), where $\\varphi$ is the phase difference between the $p_x$- and\n$p_y$-wave gap functions. Furthermore, we find that the junction exhibits an\nanisotropic magnetoelectric effect, manifesting itself as an anisotropic spin\nmagnetization along the edge of the junction.",
        "category": "cond-mat"
    },
    {
        "text": "Charge-Kondo Effect in Mesoscopic Superconductors Coupled to Normal\n  Metals: We develop a theoretical proposal for the charge Kondo effect in mesoscopic\nnormal-superconductor-normal heterostructures, where the superconducting gap\nexceeds the electrostatic charging energy. Charge-Kondo correlations in these\ndevices alter the conventional temperature-dependence of Andreev reflection and\nelectron cotunneling. We predict typical Kondo temperatures of $\\gtrsim 10 {\\rm\nmK}$, and suggest experimental architectures that combine superconducting\ncharge-qubits with semiconducting nanowires at cryogenic temperatures.",
        "category": "cond-mat"
    },
    {
        "text": "High-efficient thermoelectric materials: The case of orthorhombic IV-VI\n  compounds: Improving the thermoelectric efficiency is one of the greatest challenges in\nmaterials science. The recent discovery of excellent thermoelectric performance\nin simple orthorhombic SnSe crystal offers new promise in this prospect [Zhao\net al. Nature 508, 373 (2014)]. By calculating the thermoelectric properties of\northorhombic IV-VI compounds GeS,GeSe,SnS,and SnSe based on the\nfirst-principles combined with the Boltzmann transport theory, we show that the\nSeebeck coefficient, electrical conductivity, and thermal conductivity of\northorhombic SnSe are in agreement with the recent experiment. Importantly,\nGeS,GeSe,and SnS exhibit comparative thermoelectric performance compared to\nSnSe. Especially, the Seebeck coefficients of GeS,GeSe,and SnS are even larger\nthan that of SnSe under the studied carrier concentration and temperature\nregion. We also use the Cahill's model to estimate the lattice thermal\nconductivities at the room temperature. The large Seebeck coefficients, high\npower factors, and low thermal conductivities make these four orthorhombic\nIV-VI compounds promising candidates for high-efficient thermoelectric\nmaterials.",
        "category": "cond-mat"
    },
    {
        "text": "Dielectric function of CuBr$_\\mathrm{x}$I$_{1-\\mathrm{x}}$ alloy thin\n  films: We study the dielectric function of CuBr$_\\mathrm{x}$I$_{1-\\mathrm{x}}$ thin\nfilm alloys using spectroscopic ellipsometry in the spectral range between 0.7\neV to 6.4 eV, in combination with first-principles calculations based on\ndensity functional theory. Through the comparison of theory and experiment, we\nattribute features in the dielectric function to electronic transitions at\nspecific k-points in the Brillouin zone. The observed bandgap bowing as a\nfunction of alloy composition is discussed in terms of different physical and\nchemical contributions. The band splitting at the top of the valence band due\nto spin-orbit coupling is found to decrease with increasing Br-concentration,\nfrom a value of 660 meV for CuI to 150 meV for CuBr. This result can be\nunderstood considering the contribution of copper d-orbitals to the valence\nband maximum as a function of the alloy composition.",
        "category": "cond-mat"
    },
    {
        "text": "Thermoelectric response near a quantum critical point: the case of\n  CeCoIn5: We present a study of thermoelectric coefficients in CeCoIn_5 down to 0.1 K\nand up to 16 T in order to probe the thermoelectric signatures of quantum\ncriticality. In the vicinity of the field-induced quantum critical point, the\nNernst coefficient nu exhibits a dramatic enhancement without saturation down\nto lowest measured temperature. The dimensionless ratio of Seebeck coefficient\nto electronic specific heat shows a minimum at a temperature close to threshold\nof the quasiparticle formation. Close to T_c(H), in the vortex-liquid state,\nthe Nernst coefficient behaves anomalously in puzzling contrast with other\nsuperconductors and standard vortex dynamics.",
        "category": "cond-mat"
    },
    {
        "text": "Impurity electrons in narrow electric field-biased armchair graphene\n  nanoribbons: We present an analytical investigation of the quasi-Coulomb impurity states\nin a narrow gapped armchair graphene nanoribbon (GNR) in the presence of a\nuniform external electric field directed parallel to the ribbon axis. The\neffect of the ribbon confinement is taken to be much greater than that of the\nimpurity electric field, which in turn considerably exceeds the external\nelectric field. Under these conditions we employ the adiabatic approximation\nassuming that the motion parallel (\"slow\") and perpendicular (\"fast\") to the\nribbon axis are separated adiabatically. In the approximation of the isolated\nsize-quantized subbands induced by the \"fast\" motion the complex energies of\nthe impurity electron are calculated in explicit form. The real and imaginary\nparts of these energies determine the binding energy and width of the\nquasi-discrete state, respectively. The energy width increases with increasing\nthe electric field and ribbon width. The latter forms the background of the\nmechanism of dimensional ionization. The S-matrix - the basic tool of study of\nthe transport problems can be trivially derived from the phases of the wave\nfunctions of the continuous spectrum presented in explicit form. In the\ndouble-subband approximation we calculate the complete widths of the impurity\nstates caused by the combined effect of the electric field and the Fano\nresonant coupling between the impurity states of the discrete and continuous\nspectra associated with the ground and first excited size-quantized subbands.",
        "category": "cond-mat"
    },
    {
        "text": "Universal Dynamic Magnetism in Yb-Pyrochlores with Disparate Ground\n  States: The ytterbium pyrochlore magnets, Yb2B2O7 (B = Sn, Ti, Ge) are well described\nby S_eff = 1/2 quantum spins decorating a network of corner-sharing tetrahedra\nand interacting via anisotropic exchange. Structurally, only the non-magnetic\nB-site cation, and hence, primarily the lattice parameter, is changing across\nthe series. Nonetheless, a range of magnetic behaviors are observed: the low\ntemperature magnetism in Yb2Ti2O7 and Yb2Sn2O7 has ferromagnetic character,\nwhile Yb2Ge2O7 displays an antiferromagnetically ordered Neel state at low\ntemperatures. While the static properties of the ytterbium pyrochlores are\ndistinct, inelastic neutron scattering measurements reveal a common character\nto their exotic spin dynamics. All three ytterbium pyrochlores show a gapless\ncontinuum of spin excitations, resembling over-damped ferromagnetic spin waves\nat low Q. Furthermore, the specific heat of the series also follows a common\nform, with a broad, high-temperature anomaly followed by a sharp\nlow-temperature anomaly at T_C or T_N. The novel spin dynamics we report\ncorrelate strongly with the broad specific heat anomaly only, remaining\nunchanged across the sharp anomaly. This result suggests that the primary order\nparameter in the ytterbium pyrochlores associated with the sharp anomaly is\n\"hidden\" and not simple magnetic dipole order.",
        "category": "cond-mat"
    },
    {
        "text": "Relaxation of frustration and gap enhancement by the lattice distortion\n  in the $\u0394$ chain: We clarify an instability of the ground state of the $\\Delta$ chain against\nthe lattice distortion that increases a strength $(\\lambda)$ of a bond in each\ntriangle. It relaxes the frustration and causes a remarkable gap enhancement;\nonly a $6\\%$ increase of $\\lambda$ causes the gap doubled from the\nfully-frustrated case $(\\lambda=1)$. The lowest excitation is revealed to be a\nkink-antikink bound state whose correlation length decreases drastically with\n$\\lambda$ increase. The enhancement follows a power law, $\\Delta E_{\\rm\ngap}\\sim (\\lambda-1) + 1.44 (\\lambda -1)^{\\frac{2}{3}}$, which can be obtained\nfrom the exact result of the continuous model. This model describes a spin gap\nbehavior of the delafossite YCuO$_{2.5}$.",
        "category": "cond-mat"
    },
    {
        "text": "Direct visualization of phase separation between superconducting and\n  nematic domains in Co-doped CaFe2As2 close to a first order phase transition: We show that biaxial strain induces alternating tetragonal superconducting\nand orthorhombic nematic domains in Co substituted CaFe2As2. We use Atomic\nForce, Magnetic Force and Scanning Tunneling Microscopy (AFM, MFM and STM) to\nidentify the domains and characterize their properties, finding in particular\nthat tetragonal superconducting domains are very elongated, more than several\ntens of micron long and about 30 nm wide, have the same Tc than unstrained\nsamples and hold vortices in a magnetic field. Thus, biaxial strain produces a\nphase separated state, where each phase is equivalent to what is found at\neither side of the first order phase transition between antiferromagnetic\northorhombic and superconducting tetragonal phases found in unstrained samples\nwhen changing Co concentration. Having such alternating superconducting domains\nseparated by normal conducting domains with sizes of order of the coherence\nlength opens opportunities to build Josephson junction networks or vortex\npinning arrays and suggests that first order quantum phase transitions lead to\nnanometric size phase separation under the influence of strain.",
        "category": "cond-mat"
    },
    {
        "text": "Revealing frustrated local moment model for pressurized hyperhoneycomb\n  iridate: paving a way toward quantum spin liquid: There have been tremendous experimental and theoretical efforts toward\ndiscovery of quantum spin liquid phase in honeycomb-based-lattice materials\nwith strong spin-orbit coupling. Here the bond-dependent Kitaev interaction\nbetween local moments provides strong magnetic frustration and if it is the\nonly interaction present in the system, it will lead to an exactly solvable\nquantum spin liquid ground state. In all of these materials, however, the\nground state is in a magnetically ordered phase due to additional interactions\nbetween local moments. Recently, it has been reported that the magnetic order\nin hyperhoneycomb material, $\\beta$-Li$_2$IrO$_3$, is suppressed upon applying\nhydrostatic pressure and the resulting state becomes a quantum paramagnet or\npossibly a quantum spin liquid. Using ab-initio computations and strong\ncoupling expansion, we investigate the lattice structure and resulting local\nmoment model in pressurized $\\beta$-Li$_2$IrO$_3$. Remarkably, the dominant\ninteraction under high pressure is not the Kitaev interaction nor further\nneighbor interactions, but a different kind of bond-dependent interaction. This\nleads to strong magnetic frustration and may provide a platform for discovery\nof a new kind of quantum spin liquid ground state.",
        "category": "cond-mat"
    },
    {
        "text": "Comment on \"Theoretical analysis of quantum turbulence using the Onsager\n  ideal turbulence theory'': In a recent paper [T. Tanogami Phys. Rev. E 103, 023106 ] proposes a scenario\nfor quantum turbulence where the energy spectrum at scales smaller than the\ninter-vortex distance is dominated by a quantum stress cascade, in opposition\nto Kelvin wave cascade predictions. The purpose of the present comment is to\nhighlight some physical issues in the derivation of the quantum stress cascade,\nin particular to stress that quantization of circulation has been ignored.",
        "category": "cond-mat"
    },
    {
        "text": "Spectral and localization properties of random bipartite graphs: Bipartite graphs are often found to represent the connectivity between the\ncomponents of many systems such as ecosystems. A bipartite graph is a set of\n$n$ nodes that is decomposed into two disjoint subsets, having $m$ and $n-m$\nvertices each, such that there are no adjacent vertices within the same set.\nThe connectivity between both sets, which is the relevant quantity in terms of\nconnections, can be quantified by a parameter $\\alpha\\in[0,1]$ that equals the\nratio of existent adjacent pairs over the total number of possible adjacent\npairs. Here, we study the spectral and localization properties of such random\nbipartite graphs. Specifically, within a Random Matrix Theory (RMT) approach,\nwe identify a scaling parameter $\\xi\\equiv\\xi(n,m,\\alpha)$ that fixes the\nlocalization properties of the eigenvectors of the adjacency matrices of random\nbipartite graphs. We also show that, when $\\xi<1/10$ ($\\xi>10$) the\neigenvectors are localized (extended), whereas the\nlocalization--to--delocalization transition occurs in the interval\n$1/10<\\xi<10$. Finally, given the potential applications of our findings, we\nround off the study by demonstrating that for fixed $\\xi$, the spectral\nproperties of our graph model are also universal.",
        "category": "cond-mat"
    },
    {
        "text": "Assembly of hard spheres in a cylinder: a computational and experimental\n  study: Hard spheres are an important benchmark of our understanding of natural and\nsynthetic systems. In this work, colloidal experiments and Monte Carlo\nsimulations examine the equilibrium and out-of-equilibrium assembly of hard\nspheres of diameter $\\sigma$ within cylinders of diameter $\\sigma\\leq D\\leq\n2.82\\sigma$. Although in such a system phase transitions formally do not exist,\nmarked structural crossovers are observed. In simulations, we find that the\nresulting pressure-diameter structural diagram echoes the densest packing\nsequence obtained at infinite pressure in this range of $D$. We also observe\nthat the out-of-equilibrium self-assembly depends on the compression rate. Slow\ncompression approximates equilibrium results, while fast compression can skip\nintermediate structures. Crossovers for which no continuous line-slip exists\nare found to be dynamically unfavorable, which is the source of this\ndifference. Results from colloidal sedimentation experiments at high P\\'eclet\nnumber are found to be consistent with the results of fast compressions, as\nlong as appropriate boundary conditions are used. The similitude between\ncompression and sedimentation results suggests that the assembly pathway does\nnot here sensitively depend on the nature of the out-of-equilibrium dynamics.",
        "category": "cond-mat"
    },
    {
        "text": "Time Constants of Spin-Dependent Recombination Processes: We present experiments to systematically study the time constants of\nspin-dependent recombination processes in semiconductors using pulsed\nelectrically detected magnetic resonance (EDMR). The combination of\ntime-programmed optical excitation and pulsed spin manipulation allows us to\ndirectly measure the recombination time constants of electrons via localized\nspin pairs and the time constant of spin pair formation as a function of the\noptical excitation intensity. Using electron nuclear double resonance, we show\nthat the time constant of spin pair formation is determined by an electron\ncapture process. Based on these time constants we devise a set of rate\nequations to calculate the current transient after a resonant microwave pulse\nand compare the results with experimental data. Finally, we critically discuss\nthe effects of different boxcar integration time intervals typically used to\nanalyze pulsed EDMR experiments on the determination of the time constants. The\nexperiments are performed on phosphorus-doped silicon, where EDMR via spin\npairs formed by phosphorus donors and Si/SiO2 interface dangling bond defects\nis detected.",
        "category": "cond-mat"
    },
    {
        "text": "The Tin Pest Problem as a Test of Density Functionals Using\n  High-Throughput Calculations: At ambient pressure tin transforms from its ground-state semi-metal\n$\\alpha$-Sn (diamond structure) phase to the compact metallic $\\beta$-Sn phase\nat 13$^\\circ$C (286K). There may be a further transition to the simple\nhexagonal $\\gamma$-Sn above 450K. These relatively low transition temperatures\nare due to the small energy differences between the structures, $\\approx\n20$\\,meV/atom between $\\alpha$- and $\\beta$-Sn. This makes tin an exceptionally\nsensitive test of the accuracy of density functionals and computational\nmethods. Here we use the high-throughput Automatic-FLOW (AFLOW) method to study\nthe energetics of tin in multiple structures using a variety of density\nfunctionals. We look at the successes and deficiencies of each functional. As\nno functional is completely satisfactory, we look Hubbard U corrections and\nshow that the Coulomb interaction can be chosen to predict the correct phase\ntransition temperature. We also discuss the necessity of testing\nhigh-throughput calculations for convergence for systems with small energy\ndifferences.",
        "category": "cond-mat"
    },
    {
        "text": "Field-induced reorientation of helimagnetic order in Cu$_2$OSeO$_3$\n  probed by magnetic force microscopy: Cu$_2$OSeO$_3$ is an insulating skyrmion-host material with a magnetoelectric\ncoupling giving rise to an electric polarization with a characteristic\ndependence on the magnetic field $\\vec H$. We report magnetic force microscopy\nimaging of the helical real-space spin structure on the surface of a bulk\nsingle crystal of Cu$_2$OSeO$_3$. In the presence of a magnetic field, the\nhelimagnetic order in general reorients and acquires a homogeneous component of\nthe magnetization, resulting in a conical arrangement at larger fields. We\ninvestigate this reorientation process at a temperature of 10~K for fields\nclose to the crystallographic $\\langle 110\\rangle$ direction that involves a\nphase transition at $H_{c1}$. Experimental evidence is presented for the\nformation of magnetic domains in real space as well as for the microscopic\norigin of relaxation events that accompany the reorientation process. In\naddition, the electric polarization is measured by means of Kelvin-probe force\nmicroscopy. We show that the characteristic field dependency of the electric\npolarization originates in this helimagnetic reorientation process. Our\nexperimental results are well described by an effective Landau theory\npreviously invoked for MnSi, that captures the competition between\nmagnetocrystalline anisotropies and Zeeman energy.",
        "category": "cond-mat"
    },
    {
        "text": "Excitonic giant Zeeman effect in GaN:Mn^3+: We describe a direct observation of the excitonic giant Zeeman splitting in\n(Ga,Mn)N, a wide-gap III-V diluted magnetic semiconductor. Reflectivity and\nabsorption spectra measured at low temperatures display the A and B excitons,\nwith a shift under magnetic field due to s,p-d exchange interactions. Using an\nexcitonic model, we determine the difference of exchange integrals between\nMn^3+ and free carriers in GaN, N_0(alpha-beta)=-1.2 +/- 0.2 eV. Assuming a\nreasonable value of alpha, this implies a positive sign of beta which\ncorresponds to a rarely observed ferromagnetic interaction between the magnetic\nions and the holes.",
        "category": "cond-mat"
    },
    {
        "text": "Temperature-induced nanostructural evolution of hydrogen-rich voids in\n  amorphous silicon: A first-principles study: The paper presents an $ab$ $initio$ study of temperature-induced\nnanostructural evolution of hydrogen-rich voids in amorphous silicon. By using\nlarge $a$-Si models, obtained from classical molecular-dynamics simulations,\nwith a realistic void-volume density of 0.2%, the dynamics of Si and H atoms on\nthe surface of the nanometer-size cavities were studied and their effects on\nthe shape and size of the voids were examined using first-principles\ndensity-functional simulations. The results from $ab$ $initio$ calculations\nwere compared with those obtained from using the modified Stillinger-Weber\npotential. The temperature-induced nanostructural evolution of the voids was\nexamined by analyzing the three-dimensional distribution of Si and H atoms\non/near void surfaces using the convex-hull approximation, and computing the\nradius of gyration of the corresponding convex hulls. A comparison of the\nresults with those from the simulated values of the intensity in small-angle\nX-ray scattering of $a$-Si/$a$-Si:H in the Guinier approximation is also\nprovided, along with a discussion on the dynamics of bonded and non-bonded\nhydrogen in the vicinity of voids.",
        "category": "cond-mat"
    },
    {
        "text": "Two-Step Discontinuous Shear Thickening of Dilute Inertial Suspensions\n  Having Soft-Core Potential: Kinetic theory for dilute inertial suspension having soft-core potential is\ntheoretically investigated. From the analysis of the scattering process, the\nexpression of the scattering angle is analytically obtained. We derive the flow\ncurve between the viscosity and the shear rate, which shows two-step\ndiscontinuous shear thickening when we change the softness of the particles.\nThe molecular dynamics simulation shows that our theoretical results are\nconsistent with the numerical ones.",
        "category": "cond-mat"
    },
    {
        "text": "Field theory of absorbing phase transitions with a non-diffusive\n  conserved field: We investigate the critical behavior of a reaction-diffusion system\nexhibiting a continuous absorbing-state phase transition. The\nreaction-diffusion system strictly conserves the total density of particles,\nrepresented as a non-diffusive conserved field, and allows an infinite number\nof absorbing configurations. Numerical results show that it belongs to a wide\nuniversality class that also includes stochastic sandpile models. We derive\nmicroscopically the field theory representing this universality class.",
        "category": "cond-mat"
    },
    {
        "text": "Topological Insulator VxBi1.08-xSn0.02Sb0.9Te2S as a Promising n-type\n  Thermoelectric Material: As one of the most important n-type thermoelectric (TE) materials, Bi2Te3 has\nbeen studied for decades, with efforts to enhance the thermoelectric\nperformance based on element doping, band engineering, etc. In this study, we\nreport a novel bulk-insulating topological material system as a replacement for\nn-type Bi2Te3 materials: V doped Bi1.08Sn0.02Sb0.9Te2S (V:BSSTS) . The V:BSSTS\nis a bulk insulator with robust metallic topological surface states.\nFurthermore, the bulk band gap can be tuned by the doping level of V, which is\nverified by magnetotransport measurements. Large linear magnetoresistance is\nobserved in all samples. Excellent thermoelectric performance is obtained in\nthe V:BSSTS samples, e.g., the highest figure of merit ZT of ~ 0.8 is achieved\nin the 2% V doped sample (denoted as V0.02) at 550 K. The high thermoelectric\nperformance of V:BSSTS can be attributed to two synergistic effects: (1) the\nlow conductive secondary phases Sb2S3, and V2S3 are believed to be important\nscattering centers for phonons, leading to lower lattice thermal conductivity;\nand (2) the electrical conductivity is increased due to the high-mobility\ntopological surface states at the boundaries. In addition, by replacing one\nthird of costly tellurium with abundant, low-cost, and less-toxic sulfur\nelement, the newly produced BSSTS material is inexpensive but still has\ncomparable TE performance to the traditional Bi2Te3-based materials, which\noffers a cheaper plan for the electronics and thermoelectric industries. Our\nresults demonstrate that topological materials with unique band structures can\nprovide a new platform in the search for new high performance TE materials.",
        "category": "cond-mat"
    },
    {
        "text": "Relativistic Nonextensive Thermodynamics: Starting from the basic prescriptions of the Tsallis' nonextensive\nthermostatistics, i.e. generalized entropy and normalized q-expectation values,\nwe study the relativistic nonextensive thermodynamics and derive a Boltzmann\ntransport equation that implies the validity of the H-theorem where a local\nnonextensive four-entropy density is considered. Macroscopic thermodynamic\nfunctions and the equation of state for a perfect gas are derived at the\nequilibrium.",
        "category": "cond-mat"
    },
    {
        "text": "NMR of liquid 3He in clay pores at 1.5 K: In the present work a new method for studying porous media by nuclear\nmagnetic resonance of liquid 3He has been proposed. This method has been\ndemonstrated in an example of a clay mineral sample. For the first time the\nintegral porosity of clay sample has been measured. For investigated samples\nthe value of integral porosity is in the range of 10-30%. Inverse Laplace\ntransform of 3He longitudinal magnetization recovery curve has been carried\nout, thus distribution of relaxation times T1 has been obtained.",
        "category": "cond-mat"
    },
    {
        "text": "Collusion of Interactions and Disorder at the Superfluid-Insulator\n  Transition: A Dirty 2d Quantum Critical Point: We study the stability of the Wilson-Fisher fixed point of the quantum\n$\\mathrm{O}(2N)$ vector model to quenched disorder in the large-$N$ limit.\nWhile a random mass is strongly relevant at the Gaussian fixed point, its\neffect is screened by the strong interactions of the Wilson-Fisher fixed point.\nThis enables a perturbative renormalization group study of the interplay of\ndisorder and interactions about this fixed point. We show that, in contrast to\nthe spiralling flows obtained in earlier double-$\\epsilon$ expansions, the\ntheory flows directly to a quantum critical point characterized by finite\ndisorder and interactions. The critical exponents we obtain for this transition\nare in remarkable agreement with numerical studies of the superfluid-Mott glass\ntransition. We additionally discuss the stability of this fixed point to scalar\nand vector potential disorder and use proposed boson-fermion dualities to make\nconjectures regarding the effects of weak disorder on dual Abelian Higgs and\nChern-Simons-Dirac fermion theories when $N=1$.",
        "category": "cond-mat"
    },
    {
        "text": "Oscillatory Thickness Dependence of the Coercive Field in Magnetic 3D\n  Anti-Dot Arrays: We present studies on magnetic nano-structures with 3D architectures,\nfabricated using electrodeposition in the pores of well-ordered templates\nprepared by self-assembly of polystyrene latex spheres. The coercive field is\nfound to demonstrate an oscillatory dependence on film thickness reflecting the\npatterning transverse to the film plane. Our results demonstrate that 3D\npatterned magnetic materials are prototypes of a new class of geometrical\nmultilayer structures in which the layering is due to local shape effects\nrather then compositional differences.",
        "category": "cond-mat"
    },
    {
        "text": "On the elastic-wave imaging and characterization of fractures with\n  specific stiffness: The concept of topological sensitivity (TS) is extended to enable\nsimultaneous 3D reconstruction of fractures with unknown boundary condition and\ncharacterization of their interface by way of elastic waves. Interactions\nbetween the two surfaces of a fracture, due to e.g. presence of asperities,\nfluid, or proppant, are described via the Schoenberg's linear slip model. The\nproposed TS sensing platform is formulated in the frequency domain, and entails\npoint-wise interrogation of the subsurface volume by infinitesimal fissures\nendowed with interfacial stiffness. For completeness, the featured elastic\npolarization tensor - central to the TS formula - is mathematically described\nin terms of the shear and normal specific stiffness (ks,kn) of a vanishing\nfracture. Simulations demonstrate that, irrespective of the contact condition\nbetween the faces of a hidden fracture, the TS (used as a waveform imaging\ntool) is capable of reconstructing its geometry and identifying the normal\nvector to the fracture surface without iterations. On the basis of such\ngeometrical information, it is further shown via asymptotic analysis --\nassuming \"low frequency\" elastic-wave illumination, that by certain choices of\n(ks,kn) characterizing the trial (infinitesimal) fracture, the ratio between\nthe shear and normal specific stiffness along the surface of a nearly-panar\n(finite) fracture can be qualitatively identified. This, in turn, provides a\nvaluable insight into the interfacial condition of a fracture at virtually no\nsurcharge -- beyond the computational effort required for its imaging. The\nproposed developments are integrated into a computational platform based on a\nregularized boundary integral equation (BIE) method for 3D elastodynamics, and\nillustrated via a set of numerical experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Quantitatively consistent, scale-spanning model for same-material\n  tribocharging: By rigorously accounting for mesoscale spatial correlations in donor/acceptor\nsurface properties, we develop a scale-spanning model for same-material\ntribocharging. We find that mesoscale correlations affect not only the\nmagnitude of charge transfer but also the fluctuations-suppressing otherwise\noverwhelming charge-transfer variability that is not observed experimentally.\nWe furthermore propose a generic theoretical mechanism by which the mesoscale\nfeatures might emerge, which is qualitatively consistent with other proposals\nin the literature.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of the iron valence in the two types of layers in\n  LiFeO$_2$Fe$_2$Se$_2$: We perform electronic structure calculations for the recently synthesized\niron-based superconductor LiFeO$_2$Fe$_2$Se$_2$. In contrast to other\niron-based superconductors, this material comprises two different iron atoms in\n3$d^5$ and 3$d^6$ configurations. In band theory, both contribute to the\nlow-energy electronic structure. Spin-polarized density functional theory\ncalculations predict an antiferromagnetic metallic ground state with different\nmoments on the two Fe sites. However, several other almost degenerate magnetic\nconfigurations exist. Due to their different valences, the two iron atoms\nbehave very differently when local quantum correlations are included through\nthe dynamical mean-field theory. The contributions from the half-filled 3$d^5$\natoms in the LiFeO$_2$ layer are suppressed and the 3$d^6$ states from the FeSe\nlayer restore the standard iron-based superconductor fermiology.",
        "category": "cond-mat"
    },
    {
        "text": "A threshold model of plastic waste fragmentation: New insights into the\n  distribution of microplastics in the ocean and its evolution over time: Plastic pollution in the aquatic environment has been assessed for many years\nby ocean waste collection expeditions around the globe or by river sampling.\nWhile the total amount of plastic produced worldwide is well documented, the\namount of plastic found in the ocean, the distribution of particles on its\nsurface and its evolution over time are still the subject of much debate. In\nthis article, we propose a general fragmentation model, postulating the\nexistence of a critical size below which particle fragmentation becomes\nextremely unlikely. In the frame of this model, an abundance peak appears for\nsizes around 1mm, in agreement with real environmental data. Using, in\naddition, a realistic exponential waste feed to the ocean, we discuss the\nrelative impact of fragmentation and feed rates, and the temporal evolution of\nmicroplastics (MP) distribution. New conclusions on the temporal trend of MP\npollution are drawn.",
        "category": "cond-mat"
    },
    {
        "text": "The influence of structural variations on the constitutive response and\n  strain variations in thin fibrous materials: The stochastic variations in the structural properties of thin fiber networks\ngovern to a great extent their mechanical performance. To assess the influence\nof local structural variability on the local strain and mechanical response of\nthe network, we propose a multiscale approach combining modeling, numerical\nsimulation and experimental measurements. Based on micro-mechanical fiber\nnetwork simulations, a continuum model describing the response at the mesoscale\nlevel is first developed. Experimentally measured spatial fields of thickness,\ndensity, fiber orientation and anisotropy are thereafter used as input to a\nmacroscale finite-element model. The latter is used to simulate the impact of\nspatial variability of each of the studied structural properties. In addition,\nthis work brings novelty by including the influence of the drying condition\nduring the production process on the fiber properties. The proposed approach is\nexperimentally validated by comparison to measured strain fields and uniaxial\nresponses. The results suggest that the spatial variability in density presents\nthe highest impact on the local strain field followed by thickness and fiber\norientation. Meanwhile, for the mechanical response, the fiber orientation\nangle with respect to the drying restraints is the key influencer and its\ncontribution to the anisotropy of the mechanical properties is greater than the\ncontribution of the fiber anisotropy developed during the fiber sheet-making.",
        "category": "cond-mat"
    },
    {
        "text": "Reversible Diffusion-Limited Reactions: \"Chemical Equilibrium\" State and\n  the Law of Mass Action Revisited: The validity of two fundamental concepts of classical chemical kinetics - the\nnotion of \"Chemical Equilibrium\" and the \"Law of Mass Action\" - are re-examined\nfor reversible \\textit{diffusion-limited} reactions (DLR), as exemplified here\nby association/dissociation $A+A \\rightleftharpoons B$ reactions. We consider a\ngeneral model of long-ranged reactions, such that any pair of $A$ particles,\nseparated by distance $\\mu$, may react with probability $\\omega_+(\\mu)$, and\nany $B$ may dissociate with probability $\\omega_-(\\lambda)$ into a geminate\npair of $A$s separated by distance $\\lambda$. Within an exact analytical\napproach, we show that the asymptotic state attained by reversible DLR at $t =\n\\infty$ is generally \\textit{not a true thermodynamic equilibrium}, but rather\na non-equilibrium steady-state, and that the Law of Mass Action is invalid. The\nclassical picture holds \\text{only} in physically unrealistic case when\n$\\omega_+(\\mu) \\equiv \\omega_-(\\mu)$ for any value of $\\mu$.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-Valley Coherent Phases of the $\u03bd=0$ Quantum Hall State in Bilayer\n  Graphene: Bilayer graphene (BLG) offers a rich platform for broken symmetry states\nstabilized by interactions. In this work we study the phase diagram of BLG in\nthe quantum Hall regime at filling factor $\\nu=0$ within the Hartree-Fock\napproximation. In the simplest non-interacting situation this system has eight\n(nearly) degenerate Landau levels near the Fermi energy, characterized by spin,\nvalley, and orbital quantum numbers. We incorporate in our study two effects\nnot previously considered: (i) the nonperturbative effect of trigonal warping\nin the single-particle Hamiltonian, and (ii) short-range SU(4)\nsymmetry-breaking interactions that distinguish the energetics of the orbitals.\nWe find within this model a rich set of phases, including ferromagnetic,\nlayer-polarized, canted antiferromagnetic, Kekul\\'e, a \"spin-valley entangled\"\nstate, and a \"broken U(1) $\\times$ U(1)\" phase. This last state involves\nindependent spontaneous symmetry breaking in the layer and valley degrees of\nfreedom, and has not been previously identified. We present phase diagrams as a\nfunction of interlayer bias $D$ and perpendicular magnetic field $B_{\\perp}$\nfor various interaction and Zeeman couplings, and discuss which are likely to\nbe relevant to BLG in recent measurements. Experimental properties of the\nvarious phases and transitions among them are also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Classification of Abelian and Non-Abelian Multilayer Fractional Quantum\n  Hall States Through the Pattern of Zeros: A large class of fractional quantum Hall (FQH) states can be classified\naccording to their pattern of zeros, which describes the way ideal ground state\nwave functions go to zero as various clusters of electrons are brought\ntogether. In this paper we generalize this approach to classify multilayer FQH\nstates. Such a classification leads to the construction of a class of\nnon-Abelian multilayer FQH states that are closely related to $\\hat{g}_k$\nparafermion conformal field theories, where $\\hat{g}_k$ is an affine simple Lie\nalgebra. We discuss the possibility of some of the simplest of these\nnon-Abelian states occuring in experiments on bilayer FQH systems at $\\nu =\n2/3$, 4/5, 4/7, etc.",
        "category": "cond-mat"
    },
    {
        "text": "Temperature Induced Shifts of Yu-Shiba-Rusinov Resonances in\n  Nanowire-Based Hybrid Quantum Dots: The strong coupling of a superconductor to a spinful quantum dot results in\nYu-Shiba-Rusinov (YSR) discrete subgap excitations. In isolation and at zero\ntemperature, the excitations are $\\delta$ resonances. In transport experiments,\nhowever, they show as broad differential conductance peaks. We obtain the\nlineshape of the peaks and their temperature dependence in\nsuperconductor-quantum-dot-metal (S-QD-N) nanowire-based devices. Unexpectedly,\nwe find that the peaks shift in energy with temperature, with the shift\nmagnitude and sign depending on ground state parity and bias voltage.\nAdditionally, we empirically find a power-law scaling of the peak area versus\ntemperature. These observations are not explained by current models.",
        "category": "cond-mat"
    },
    {
        "text": "Duality in quantum transport models: We develop the `duality approach', that has been extensively studied for\nclassical models of transport, for quantum systems in contact with a thermal\n`Lindbladian' bath. The method provides (a) a mapping of the original model to\na simpler one, containing only a few particles and (b) shows that any dynamic\nprocess of this kind with generic baths may be mapped onto one with equilibrium\nbaths. We exemplify this through the study of a particular model: the quantum\nsymmetric exclusion process introduced in [D. Bernard, T. Jin, Phys. Rev. Lett.\n123, 080601 (2019)]. As in the classical case, the whole construction becomes\nintelligible by considering the dynamical symmetries of the problem.",
        "category": "cond-mat"
    },
    {
        "text": "Entangled quantum currents in distant mesoscopic Josephson junctions: Two mesoscopic SQUID rings which are far from each other, are considered. A\nsource of two-mode nonclassical microwaves irradiates the two rings with\ncorrelated photons. The Josephson currents are in this case quantum mechanical\noperators, and their expectation values with respect to the density matrix of\nthe microwaves, yield the experimentally observed currents. Classically\ncorrelated (separable) and quantum mechanically correlated (entangled)\nmicrowaves are considered, and their effect on the Josephson currents is\nquantified. Results for two different examples that involve microwaves in\nnumber states and coherent states are derived. It is shown that the quantum\nstatistics of the tunnelling electron pairs through the Josephson junctions in\nthe two rings, are correlated.",
        "category": "cond-mat"
    },
    {
        "text": "Hot Brownian Motion of thermoresponsive microgels in optical tweezers\n  shows discontinuous volume phase transition and bistability: Microgels are soft microparticles that often exhibit thermoresponsiveness and\nfeature a transformation at a critical temperature, referred to as the volume\nphase transition temperature. The question of whether this transformation\noccurs as a smooth or as a discontinuous one is still a matter of debate. This\nquestion can be addressed by studying individual microgels trapped in optical\ntweezers. For this aim, composite particles were obtained by decorating pNIPAM\nmicrogels with iron oxide nanocubes. These composites become self-heating when\nilluminated by the infrared trapping laser, featuring Hot Brownian Motion\nwithin the trap. Above a certain laser power, a single decorated microgel\nfeatures a volume phase transition that is discontinuous, while the usual\ncontinuous sigmoidal-like dependence is recovered after averaging over\ndifferent microgels. The collective sigmoidal behavior enables the application\nof a power-to-temperature calibration and provides the effective drag\ncoefficient of the self-heating microgels, thus establishing these composite\nparticles as potential micro-thermometers and micro-heaters. Moreover, the\nself-heating microgels also exhibit an unexpected and intriguing bistability\nbehavior above the critical temperature, probably due to partial collapses of\nthe microgel. These results set the stage for further studies and the\ndevelopment of applications based on the Hot Brownian Motion of soft particles.",
        "category": "cond-mat"
    },
    {
        "text": "Hydration at highly crowded interfaces: Understanding the molecular and electronic structure of electrolytes at\ninterfaces requires an analysis of the interactions between the electrode\nsurface, the ions, and the solvent environment on equal footing. Here, we\ntackle this challenge by exploring the initial stages of Cs+ hydration on a\nCu(111) surface by combining experiment and theory. Remarkably, we observe\n\"inside out\" solvation of Cs ions, i.e, their preferential location at the\nperimeter of the water clusters on the metal surface. In addition, water-Cs\ncomplexes containing multiple Cs+ ions are observed to form at these surfaces.\nEstablished models based on maximum ion-water coordination and the double layer\nnotion cannot account for this situation and the complex interplay of\nmicroscopic interactions is the key to a fundamental understanding.",
        "category": "cond-mat"
    },
    {
        "text": "Stiffening graphene by controlled defect creation: Graphene extraordinary strength, stiffness and lightness have generated great\nexpectations towards its application in flexible electronics and as mechanical\nreinforcement agent. However, the presence of lattice defects, unavoidable in\nsheets obtained by scalable routes, might degrade its mechanical properties.\nHere we report a systematic study on the elastic modulus and strength of\ngraphene with controlled density of defects. Counter intuitively, the in-plane\nYoung modulus increases with increasing defect density up to almost twice the\ninitial value for vacancy content of ~0.2%, turning it into the stiffest\nmaterial ever reported. For higher density of vacancies, elastic modulus\ndecreases with defect inclusion. The initial increase in Young modulus is\nexplained in terms of a dependence of the elastic coefficients with the\nmomentum of flexural modes predicted for 2D membranes. In contrast, the\nfracture strength decreases with defect density according to standard fracture\ncontinuum models. These quantitative structure-property relationships, measured\nin atmospheric conditions, are of fundamental and technological relevance and\nprovide guidance for applications in which graphene mechanics represents a\ndisruptive improvement.",
        "category": "cond-mat"
    },
    {
        "text": "FFLO or Majorana superfluids: The fate of fermionic cold atoms in\n  spin-orbit coupled optical lattices: The recent experimental realization of spin-orbit coupling (SOC) for\nultra-cold atoms opens a completely new avenue for exploring new quantum\nmatter. In experiments, the SOC is implemented simultaneously with a Zeeman\nfield. Such spin-orbit coupled Fermi gases are predicted to support Majorana\nfermions with non-Abelian exchange statistics in one dimension (1D). However,\nas shown in recent theory and experiments for 1D spin-imbalanced Fermi gases,\nthe Zeeman field can lead to the long-sought Fulde-Ferrell-Larkin-Ovchinnikov\n(FFLO) superfluids with non-zero momentum Cooper pairings, in contrast to the\nzero momentum pairing in Majorana superfluids. Therefore a natural question to\nask is which phase, FFLO or Majorana superfluids, will survive in spin-orbit\ncoupled Fermi gases in the presence of a large Zeeman field. In this paper, we\naddress this question by studying the mean field quantum phases of 1D\n(quasi-1D) spin-orbit coupled fermionic cold atom optical lattices.",
        "category": "cond-mat"
    },
    {
        "text": "Thermodynamics of volume collapse transitions in cerium and related\n  compounds: We present a non-linear elastic model of a coherent transition with\ndiscontinuous volume change in an isotropic solid. The model reproduces the\nanomalous thermodynamics typical of coherent equilibrium including intrinsic\nhysteresis (for a pressure driven experiment) and a negative bulk modulus. The\nnovelty of the model is that the statistical mechanics solution can be easily\nworked out. We find that coherency leads to an infinite-range density--density\ninteraction, which drives classical critical behavior. The pressure width of\nthe hysteresis loop shrinks with increasing temperature, ending at a critical\npoint at a temperature related to the shear modulus. The bulk modulus softens\nwith a 1/2 exponent at the transition even far from the critical point. Many\nwell known features of the phase diagram of Ce and related systems are\nexplained by the model.",
        "category": "cond-mat"
    },
    {
        "text": "Superconductivity in layered Zintl phase LiSn2As2: We report the superconductivity in the layered Zintl phase LiSn$_2$As$_2$,\nwhich is isostructural to NaSn$_2$As$_2$ and has a transition temperature\n($T_{\\mathrm{c}}$) of 1.6 K. Despite similar $T_{\\mathrm{c}}$ and Debye\ntemperatures, substituting of Na with Li considerably increases the upper\ncritical field. Based on a systematically comparation of Sn$_4$As$_3$, NaSnAs,\nNaSn$_2$As$_2$,Na$_{1-x}$Sn$_2$P$_2$, SrSn$_2$As$_2$, and LiSn$_2$As$_2$, we\npropose that carrier doping, intimately related to the formation of lone-pair\nelectrons, controls superconductivity in layered SnAs-based compounds rather\nthan chemical pressure. The current findings provide a thorough and\ncomprehensive understanding of Sn-based Zintl phase.",
        "category": "cond-mat"
    },
    {
        "text": "Topological d-wave pairing structures in Jain states: We discuss d-wave topological (broken time reversal symmetry) pairing\nstructures in unpolarized and polarized Jain states. We demonstrate pairing in\nthe Jain spin singlet state by rewriting it in an explicit pairing form, in\nwhich we can recognize d-wave weak pairing of underlying quasiparticles -\nneutral fermions. We find and describe the root configuration of the Jain spin\nsinglet state and its connection with neutral excitations of the Haldane-Rezayi\nstate, and study the transition between these states via exact diagonalization.\nWe find high overlaps with the Jain spin singlet state upon a departure from\nthe hollow core model for which the Haldane-Rezayi state is the exact ground\nstate. Due to a proven algebraic identity we were able to extend the analysis\nof topological d-wave pairing structures to polarized Jain states and integer\nquantum Hall states, and discuss its consequences.",
        "category": "cond-mat"
    },
    {
        "text": "Topological and holonomic quantum computation based on second-order\n  topological superconductors: Majorana fermions feature non-Abelian exchange statistics and promise\nfascinating applications in topological quantum computation. Recently,\nsecond-order topological superconductors (SOTSs) have been proposed to host\nMajorana fermions as localized quasiparticles with zero excitation energy,\npointing out a new avenue to facilitate topological quantum computation. We\nprovide a minimal model for SOTSs and systematically analyze the features of\nMajorana zero modes with analytical and numerical methods. We further construct\nthe fundamental fusion principles of zero modes stemming from a single or\nmultiple SOTS islands. Finally, we propose concrete schemes in different setups\nformed by SOTSs, enabling us to exchange and fuse the zero modes for\nnon-Abelian braiding and holonomic quantum gate operations.",
        "category": "cond-mat"
    },
    {
        "text": "A new model to describe the physics of VOPO: In the past different models for the magnetic salt vanadyl pyrophosphate\n(VOPO) were discussed. Neither a spin ladder nor an alternating chain are\ncapable to describe recently measured magnetic excitations. In this paper we\npropose a 2D model that fits better to experimental observations.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-ladders with spin gaps: A description of a class of cuprates: We investigate the magnetic properties of the Cu-O planes in stoichiometric\nSr$_{n-1}$Cu$_{n+1}$O$_{2n}$ (n=3,5,7,...) which consist of CuO double chains\nperiodically intergrown within the CuO$_2$ planes. The double chains break up\nthe two-dimensional antiferromagnetic planes into Heisenberg spin ladders with\n$n_r=\\frac{1}{2}(n-1)$ rungs and $n_l=\\frac{1}{2}(n+1)$ legs and described by\nthe usual antiferromagnetic coupling J inside each ladder and a weak and\nfrustrated interladder coupling J$^\\prime$. The resulting lattice is a new\ntwo-dimensional trellis lattice. We first examine the spin excitation spectra\nof isolated quasi one dimensional Heisenberg ladders which exhibit a gapless\nspectra when $n_r$ is even and $n_l$ is odd ( corresponding to n=5,9,...) and a\ngapped spectra when $n_r$ is odd and $n_l$ is even (corresponding to\nn=3,7,...). We use the bond operator representation of quantum $S=\\frac{1}{2}$\nspins in a mean field treatment with self-energy corrections and obtain a spin\ngap of $\\approx \\frac{1}{2} J$ for the simplest single rung ladder (n=3), in\nagreement with numerical estimates.",
        "category": "cond-mat"
    },
    {
        "text": "In-situ measurements of the optical absorption of dioxythiophene-based\n  conjugated polymers: Conjugated polymers can be reversibly doped by electrochemical means. This\ndoping introduces new sub-bandgap optical absorption bands in the polymer while\ndecreasing the bandgap absorption. To study this behavior, we have prepared an\nelectrochemical cell allowing measurements of the optical properties of the\npolymer. The cell consists of a thin polymer film deposited on gold-coated\nMylar behind which is another polymer that serves as a counterelectrode. An\ninfrared transparent window protects the upper polymer from ambient air. By\nadding a gel electrolyte and making electrical connections to the\npolymer-on-gold films, one may study electrochromism in a wide spectral range.\nAs the cell voltage (the potential difference between the two electrodes)\nchanges, the doping level of the conjugated polymer films is changed\nreversibly. Our experiments address electrochromism in\npoly(3,4-ethylene-dioxy-thiophene) (PEDOT) and\npoly(3,4-dimethyl-propylene-dioxy-thiophene) (PProDOT-Me$_2$). This closed\nelectrochemical cell allows the study of the doping induced sub-bandgap\nfeatures (polaronic and bipolaronic modes) in these easily oxidized and highly\nredox switchable polymers. We also study the changes in cell spectra as a\nfunction of polymer thickness and investigate strategies to obtain cleaner\nspectra, minimizing the contributions of water and gel electrolyte features.",
        "category": "cond-mat"
    },
    {
        "text": "Octonacci Photonic Crystals with Negative Refraction Index Materials: We investigate the optical transmission spectra for $s$-polarized (TE) and\n$p$-polarized (TM) waves in one-dimensional photonic quasicrystals on a\nquasiperiodic multilayer structure made up by alternate layers of SiO$_{2}$ and\n\\textit{metamaterials}, organized by following the Octonacci sequence.\nMaxwell's equations and the transfer-matrix technique are used to derive the\ntransmission spectra for the propagation of normaly and obliquely incident\noptical fields. We assume Drude-Lorentz-type dispersive response for the\ndielectric permittivity and magnetic permeability of the metamaterials. For\nnormally incident waves, we observe that the spectra does not have self-similar\nbehavior or mirror symmetry and it also features the absence of optical band\ngap. Also for normally incident waves, we show regions of full transmittance\nwhen the incident angle $\\theta_{C} = 0^{\\circ}$ in a particular frequency\nrange.",
        "category": "cond-mat"
    },
    {
        "text": "Scale invariance and superfluid turbulence: We construct a Schroedinger field theory invariant under local spatial\nscaling. It is shown to provide an effective theory of superfluid turbulence by\nderiving, analytically, the observed Kolmogorov 5/3 law and to lead to a\nBiot-Savart interaction between the observed filament excitations of the system\nas well.",
        "category": "cond-mat"
    },
    {
        "text": "Surface criticality in random field magnets: The boundary-induced scaling of three-dimensional random field Ising magnets\nis investigated close to the bulk critical point by exact combinatorial\noptimization methods. We measure several exponents describing surface\ncriticality: $\\beta_1$ for the surface layer magnetization and the surface\nexcess exponents for the magnetization and the specific heat, $\\beta_s$ and\n$\\alpha_s$. The latter ones are related to the bulk phase transition by the\nsame scaling laws as in pure systems, but only with the same violation of\nhyperscaling exponent $\\theta$ as in the bulk. The boundary disorders faster\nthan the bulk, and the experimental and theoretical implications are discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Spin Glass in a Field: a New Zero-Temperature Fixed Point in Finite\n  Dimensions: By using real space renormalisation group (RG) methods we show that\nspin-glasses in a field display a new kind of transition in high dimensions.\nThe corresponding critical properties and the spin-glass phase are governed by\ntwo non-perturbative zero temperature fixed points of the RG flow. We compute\nthe critical exponents, discuss the RG flow and its relevance for three\ndimensional systems. The new spin-glass phase we discovered has unusual\nproperties, which are intermediate between the ones conjectured by droplet and\nfull replica symmetry breaking theories. These results provide a new\nperspective on the long-standing debate about the behaviour of spin-glasses in\na field.",
        "category": "cond-mat"
    },
    {
        "text": "Structure and magnetism in $\\rm LaCoO_3$: The temperature dependence of the hexagonal lattice parameter $c$ of single\ncrystal $\\rm LaCoO_3$ (LCO) with $H=0$ and $800$Oe, as well as LCO bulk powders\nwith $H=0$, was measured using high-resolution x-ray scattering near the\ntransition temperature $T_o\\approx 35$K. The change of $c(T)$ is well\ncharacterized by a power law in $T-T_o$ for $T>T_o$ and by a temperature\nindependent constant for $T<T_o$ when convoluted with a Gaussian function of\nwidth $8.5$K. This behavior is discussed in the context of the unusual magnetic\nbehavior observed in LCO as well as recent generalized gradient approximation\ncalculations.",
        "category": "cond-mat"
    },
    {
        "text": "Single-dot spectroscopy via elastic single-electron tunneling through a\n  pair of coupled quantum dots: We study the electronic structure of a single self-assembled InAs quantum dot\nby probing elastic single-electron tunneling through a single pair of weakly\ncoupled dots. In the region below pinch-off voltage, the non-linear threshold\nvoltage behavior provides electronic addition energies exactly as the linear,\nCoulomb blockade oscillation does. By analyzing it, we identify the s and p\nshell addition spectrum for up to six electrons in the single InAs dot, i.e.\none of the coupled dots. The evolution of shell addition spectrum with magnetic\nfield provides Fock-Darwin spectra of s and p shell.",
        "category": "cond-mat"
    },
    {
        "text": "Singular low-energy states of tilted Dirac semimetals induced by the\n  fermion-fermion interactions: We attentively investigate the effects of short-range fermion-fermion\ninteractions on the low-energy properties of both two-dimensional type-I and\ntype-II tilted Dirac semimetals by means of the renormalization group\nframework. Practicing the standard renormalization group procedures via taking\ninto account all one-loop corrections gives rise to the coupled\nenergy-dependent evolutions of all interaction parameters, which are adopted to\ncarefully examine whether and how the fermion-fermion interactions influence\nthe low-energy physical behaviors of tilted Dirac fermions. After carrying out\nthe detailed analysis of coupled flows, we figure out the tilting parameter\ndictates the low-energy states of tilted Dirac fermions in conjunction with\nstarting values of fermion-fermion couplings. With proper variations of these\ntwo kinds of parameters, the tilted Dirac fermions can either flow towards the\nGaussian fixed point or undergo certain instability that is conventionally\naccompanied by a phase transition in the low-energy regime. In addition, all\npotential instabilities can be clustered into five distinct classes owing to\nthe competitions between the tilting parameter and initial fermionic\ninteractions. Moreover, the dominant phases accompanied by the instabilities\nare determined via computing and comparing the susceptibilities of eight\npotential phases.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic structure and exchange interactions in the layered\n  semiconductor CrPS4: Compounds with two-dimensional (2D) layers of magnetic ions weakly connected\nby van der Waals bonding offer routes to enhance quantum behavior, stimulating\nboth fundamental and applied interest. CrPS4 is one such magnetic van der Waals\nmaterial, however, it has undergone only limited investigation. Here we present\na comprehensive series of neutron scattering measurements to determine the\nmagnetic structure and exchange interactions. The observed magnetic excitations\nallow a high degree of constraint on the model parameters not normally\nassociated with measurements on a powder sample. The results demonstrate the 2D\nnature of the magnetic interactions, while also revealing the importance of\ninteractions along 1D chains within the layers. The subtle role of competing\ninteractions is observed, which manifest in a non-trivial magnetic transition\nand a tunable magnetic structure in a small applied magnetic field through a\nspin-flop transition. Our results on the bulk compound provide insights that\ncan be applied to an understanding of the behavior of reduced layer CrPS4.",
        "category": "cond-mat"
    },
    {
        "text": "The angular momentum of a magnetically trapped atomic condensate: For an atomic condensate in an axially symmetric magnetic trap, the sum of\nthe axial components of the orbital angular momentum and the hyperfine spin is\nconserved. Inside an Ioffe-Pritchard trap (IPT) whose magnetic field (B-field)\nis not axially symmetric, the difference of the two becomes surprisingly\nconserved. In this paper we investigate the relationship between the values of\nthe sum/difference angular momentums for an atomic condensate inside a magnetic\ntrap and the associated gauge potential induced by the adiabatic approximation.\nOur result provides significant new insight into the vorticity of magnetically\ntrapped atomic quantum gases.",
        "category": "cond-mat"
    },
    {
        "text": "Hybrid density functional theory study on zinc blende GaN and diamond\n  surfaces and interfaces: Effects of size, hydrogen passivation and dipole\n  corrections: GaN based high electron mobility transistors show promise in numerous device\napplications which elicits the need for accurate models of bulk, surface, and\ninterface electronic properties. We detail here a hybrid density functional\ntheory study of zinc blende (zb) GaN and diamond bulk and surface properties,\nand zb GaN on diamond interfaces using slab supercell models. Details are\nprovided on the dependence of electronic properties with respect to supercell\nsize, the use of pseudo-hydrogen to passivate the bottom GaN layer, and dipole\ncorrections. The large bulk modulus of diamond provides a templating structure\nfor GaN to grow upon, where a large lattice mismatch is accounted for through\nthe inclusion of a cationic Ga adlayer. Looking at both type I and II surfaces\nand interfaces of GaN shows the instability of zb GaN without an adlayer (type\nII), where increased size, pseudo-hydrogen passivation and dipole corrections\ndo not remove the spurious interaction between the top and bottom layers in\ntype II GaN. Layer dependent density of states, local potential differences,\nand charge density differences show that the type I interface (with a Ga\nadlayer) is stable with an adhesion energy of 0.704 eV/{\\AA}2 (4.346 J/m2);\ninterestingly, the diamond charge density intercalates into the first layer of\nGaN, which was seen experimentally for wurtzite GaN grown over diamond. The\ntype II interface is shown to be unstable which implies that, to form a stable,\nthin-film zb interface between GaN and diamond, the partial pressure of\ntrimethylgallium must be controlled to ensure a Ga layer exists both on the top\nand bottom layer of the GaN thin film atop the diamond. We believe our results\ncan shed light towards a better understanding of the GaN/diamond multifaceted\ninterface present in the GaN overgrowth on diamond samples.",
        "category": "cond-mat"
    },
    {
        "text": "Scaling of the conductance in gold nanotubes: A new form of gold nanobridges has been recently observed in ultrahigh-vacuum\nexperiments, where the gold atoms rearrange to build helical nanotubes, akin in\nsome respects to carbon nanotubes. The good reproducibility of these wires and\ntheir unexpected stability will allow for conductance measurements and make\nthem promising candidates for future applications . We present here a study of\nthe transport properties of these nanotubes in order to understand the role of\nchirality and of the different orbitals in quantum transport observables. The\nconductance per atomic row shows a light decreasing trend as the diameter\ngrows, which is also shown through an analytical formula based on a one-orbital\nmodel.",
        "category": "cond-mat"
    },
    {
        "text": "Microstructure and Fe-vacancy ordering in the KFexSe2 superconducting\n  system: Structural investigations by means of transmission electron microscopy (TEM)\non KFexSe2 with 1.5 \\leq x \\leq 1.8 have revealed a rich variety of\nmicrostructure phenomena, the KFe1.5Se2 crystal often shows a superstructure\nmodulation along the [310] zone-axis direction, this superstructure can be well\ninterpreted by the Fe-vacancy order within the a-b plane. Increase of\nFe-concentration in the KFexSe2 materials could not only result in the\nappearance of superconductivity but also yield clear alternations of\nmicrostructure. Structural inhomogeneity, the complex superstructures and\ndefect structures in the superconducting KFe1.8Se2 sample have been\ninvestigated based on the high-resolution TEM.",
        "category": "cond-mat"
    },
    {
        "text": "Magneto-Seebeck effect in bismuth: Thermoelectricity was discovered almost two centuries ago in bismuth. The\nlarge and negative Seebeck coefficient of this semimetal remains almost flat\nbetween 300 K and 100 K. This striking feature can be understood by considering\nthe ratio of electron and hole mobilities and the evolution of their equal\ndensities with temperature. The large and anisotropic magneto-Seebeck effect in\nbismuth, on the other hand, has not been understood up to the present day.\nHere, we report on a systematic study of the thermopower of bismuth from room\ntemperature down to 20 K upon application of a magnetic field of 13.8 T in the\nbinary-bisectrix plane. The amplitude of the Seebeck coefficient depends on the\norientation of the magnetic field and the anisotropy changes sign with\ndecreasing temperature. The magneto-Seebeck effect becomes non-monotonic at low\ntemperatures. When the magnetic field is oriented along the binary axis, the\nSeebeck coefficient is not the same for positive and negative fields. This\nso-called Umkehr effect arises because the high symmetry axes of the Fermi\nsurface ellipsoids are neither parallel to each other nor to the high symmetry\naxes of the lattice. The complex evolution of thermopower can be accounted for\nin a large part of the ($T,B,\\Theta$)-space by a model based on semiclassical\ntransport theory and incorporating Landau quantization. The employed energy\ndependence of the scattering time is compatible with electron-acoustic phonon\nscattering. We find that the transverse Nernst response plays an important role\nin setting the amplitude of the longitudinal magneto-Seebeck effect.\nFurthermore, Landau quantization significantly affects thermoelectricity up to\ntemperatures as high as 120 K.",
        "category": "cond-mat"
    },
    {
        "text": "Size quantization of an exciton: A toy model of the \"dead layer\": Size-quantization levels of an exciton in large nanocrystals is studied\ntheoretically. For the nanocrystal size, $L$, much bigger than the Bohr radius,\n$a_B$, the level positions do not depend on $a_B$. The correction to the levels\nin a small parameter $a_B/L$ depends on the reflection phase of the exciton\nfrom the boundary. Calculation of this phase constitutes a three-body problem:\nelectron, hole, and the boundary. This calculation can be performed\nanalytically in the limit when the hole is much heavier than the electron.\nPhysically, a slow motion of the hole towards the boundary takes place in the\neffective potential created by the fast motion of the electron orbiting the\nhole and touching the boundary. As a result, the hole is reflected before\nreaching the boundary. The distance of the closest approach of the hole to the\nboundary (the dead layer) exceeds $a_B$ parametrically.",
        "category": "cond-mat"
    },
    {
        "text": "Internal Space Renormalization Group Methods for Atomic and Condensed\n  Matter Physics: The functional renormalization group method is used to take into account the\nvacuum polarization around localized bound states generated by external\npotential. The application to Atomic Physics leads to improved Hartree-Fock and\nKohn-Sham equations in a systematic manner within the framework of the Density\nFunctional Theory. Another application to Condensed Matter Physics consists of\nan algorithm to compute quenched averages with or without Coulomb interaction\nin a non-perturbative manner.",
        "category": "cond-mat"
    },
    {
        "text": "A note on generalized hydrodynamics: inhomogeneous fields and other\n  concepts: Generalized hydrodynamics (GHD) was proposed recently as a formulation of\nhydrodynamics for integrable systems, taking into account infinitely-many\nconservation laws. In this note we further develop the theory in various\ndirections. By extending GHD to all commuting flows of the integrable model, we\nprovide a full description of how to take into account weakly varying force\nfields, temperature fields and other inhomogeneous external fields within GHD.\nWe expect this can be used, for instance, to characterize the non-equilibrium\ndynamics of one-dimensional Bose gases in trap potentials. We further show how\nthe equations of state at the core of GHD follow from the continuity relation\nfor entropy, and we show how to recover Euler-like equations and discuss\npossible viscosity terms.",
        "category": "cond-mat"
    },
    {
        "text": "A kinetic model for the finite-time thermodynamics of small heat engines: We study a molecular engine constituted by a gas of $N \\sim 10^2$ molecules\nenclosed between a massive piston and a thermostat. The force acting on the\npiston and the temperature of the thermostat are cyclically changed with a\nfinite period $\\tau$. In the adiabatic limit $\\tau \\to \\infty$, even for finite\nsize $N$, the average work and heats reproduce the thermodynamic values,\nrecovering the Carnot result for the efficiency. The system exhibits a stall\ntime $\\tau^*$ where net work is zero: for $\\tau<\\tau^*$ it consumes work\ninstead of producing it, acting as a refrigerator or as a heat sink. At\n$\\tau>\\tau^*$ the efficiency at maximum power is close to the Curzorn-Ahlborn\nlimit. The fluctuations of work and heat display approximatively a Gaussian\nbehavior. Based upon kinetic theory, we develop a three-variables Langevin\nmodel where the piston's position and velocity are linearly coupled together\nwith the internal energy of the gas. The model reproduces many of the system's\nfeatures, such as the inversion of the work's sign, the efficiency at maximum\npower and the approximate shape of fluctuations. A further simplification in\nthe model allows to compute analytically the average work, explaining its\nnon-trivial dependence on $\\tau$.",
        "category": "cond-mat"
    },
    {
        "text": "Flow can order: Phases of live XY spins in two dimensions: We present the hydrodynamic theory of active XY spins coupled with flow\nfields, for systems both having and or lacking number conservation in two\ndimensions (2D). For the latter, with strong activity or nonequilibrium drive,\nthe system can synchronize, or be phase-ordered with various types of order,\ne.g., quasi long range order (QLRO) or new kind of order weaker or stronger\nthan QLRO for sufficiently strong active flow-phase couplings. For the number\nconserving case, the system can show QLRO or order weaker than QLRO, again for\nsufficiently strong active flow-phase couplings. For other choices of the model\nparameters, the system necessarily disorders in a manner similar to immobile\nbut active XY spins, or 2D Kardar-Parisi-Zhang surfaces.",
        "category": "cond-mat"
    },
    {
        "text": "The electronic and transport properties of a molecular junction studied\n  by an integrated piecewise thermal equilibrium approach: An integrated piecewise thermal equilibrium approach based on the\nfirst-principles calculation method has been developed to calculate bias\ndependent electronic structures and current- and differential\nconductance-voltage characteristics of the gold-benzene-1,4-dithiol-gold\nmolecular junction. The calculated currents and differential conductance have\nthe same order of magnitude as experimental ones. An electron transfer was\nfound between the two electrodes when a bias is applied, which renders the two\nelectrodes to have different local electronic structures. It was also found\nthat when Au 5d electrons were treated as core electrons the calculated\ncurrents were overestimated, which can be understood as an underestimate of the\nAu-S covalent bonding and consequently the contact potential barrier and the\nreplacement of delocalized Au 5d carriers by more itinerant delocalized Au 6sp\ncarriers in the electrodes.",
        "category": "cond-mat"
    },
    {
        "text": "Hopf-link multi-Weyl-loop topological semimetals: We construct a generic two-band model which can describe topological Weyl\nsemimetals with multiple closed Weyl loops. All the existing multi-Weyl-loop\nsemimetals including the nodal-net, or nodal-chain and Hopf-link states can be\nexamined within one same framework. Based on a two-loop model, the\ncorresponding drum-head surface states for these topologically different bulk\nstates are studied and compared with each other. The connection of our model\nwith Hopf insulators is also discussed. Furthermore, to identify experimentally\nthese topologically different Weyl semimetal states, especially distinguish the\nHopf-link from unlinked ones, we also investigate their Landau levels. It is\nfound that the Hopf-link state can be characterized by the existence of a\nquadruply degenerate zero-energy Landau band, regardless of the direction of\nthe magnetic field.",
        "category": "cond-mat"
    },
    {
        "text": "Spontaneous symmetry breaking: exact results for a biased random walk\n  model of an exclusion process: It has been recently suggested that a totally asymmetric exclusion process\nwith two species on an open chain could exhibit spontaneous symmetry breaking\nin some range of the parameters defining its dynamics. The symmetry breaking is\nmanifested by the existence of a phase in which the densities of the two\nspecies are not equal. In order to provide a more rigorous basis to these\nobservations we consider the limit of the process when the rate at which\nparticles leave the system goes to zero. In this limit the process reduces to a\nbiased random walk in the positive quarter plane, with specific boundary\nconditions. The stationary probability measure of the position of the walker in\nthe plane is shown to be concentrated around two symmetrically located points,\none on each axis, corresponding to the fact that the system is typically in one\nof the two states of broken symmetry in the exclusion process. We compute the\naverage time for the walker to traverse the quarter plane from one axis to the\nother, which corresponds to the average time separating two flips between\nstates of broken symmetry in the exclusion process. This time is shown to\ndiverge exponentially with the size of the chain.",
        "category": "cond-mat"
    },
    {
        "text": "Delay and distortion of slow light pulses by excitons in ZnO: Light pulses propagating through ZnO undergo distortions caused by both bound\nand free excitons. Numerous lines of bound excitons dissect the pulse and\ninduce slowing of light around them, to the extend dependent on their nature.\nExciton-polariton resonances determine the overall pulse delay and attenuation.\nThe delay time of the higher-energy edge of a strongly curved light stripe\napproaches 1.6 ns at 3.374 eV with a 0.3 mm propagation length. Modelling the\ndata of cw and time-of-flight spectroscopies has enabled us to determine the\nexcitonic parameters, inherent for bulk ZnO. We reveal the restrictions on\nthese parameters induced by the light attenuation, as well as a discrepancy\nbetween the parameters characterizing the surface and internal regions of the\ncrystal.",
        "category": "cond-mat"
    },
    {
        "text": "Optical orientation of nuclei in nitrogen alloys GaAsN at room\n  temperature: The intensity and the giant circular polarization of edge luminescence in a\nlongitudinal magnetic field have been measured in nitrogen alloys GaAsN under\ncircularly polarized pumping. It has been found that these dependences are\nshifted with respect to zero field by a value Beff. The magnitude of the\ninternal field Beff increases with increase in pumping intensity and reaches\nsaturation (~250 Gauss) at great densities of excitation. The saturation of the\nBeff field with growth of pumping indicates that this is a field of nuclei,\npolarized dynamically due to hyperfine interaction with optically oriented deep\nparamagnetic centers, rather than a field of exchange interaction created on\nthe center by spin-polarized photo-excited conduction electrons. The short time\nof nuclear polarization by electrons (<15 mks), measured under modulation of\ncircular polarization of the exciting light with high frequency, points to a\nsmall number of nuclei undergoing hyperfine interaction with an electron\nlocalized at a center.",
        "category": "cond-mat"
    },
    {
        "text": "Self-assembly of multicomponent structures in and out of equilibrium: Theories of phase change and self-assembly often invoke the idea of a\n`quasiequilibrium', a regime in which the nonequilibrium association of\nbuilding blocks results nonetheless in a structure whose properties are\ndetermined solely by an underlying free energy landscape. Here we study a\nprototypical example of multicomponent self-assembly, a one-dimensional fiber\ngrown from red and blue blocks. If the equilibrium structure possesses\ncompositional correlations different from those characteristic of random\nmixing, then it cannot be generated without error at any finite growth rate:\nthere is no quasiequilibrium regime. However, by exploiting dynamic scaling,\nstructures characteristic of equilibrium at one point in phase space can be\ngenerated, without error, arbitrarily far from equilibrium. Our results thus\nsuggest a `nonperturbative' strategy for multicomponent self-assembly in which\nthe target structure is, by design, not the equilibrium one.",
        "category": "cond-mat"
    },
    {
        "text": "Clusters in a magnetic toy model for binary granular piles: Results on a generalized magnetically controlled ballistic deposition (MBD)\nmodel of granular piles are reported in order to search for the effect of \"spin\nflip\" probability q in building a granular pile. Two different regimes of spin\ncluster site distributions have been identified, a border line $q_c(\\beta J)$\nwhere J is the interaction potential strength.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum body in uniform magnetic fields: In this article it will be presented the first attempt made in order to\nperform gauge invariant calculations of eigenstates of a quantum body in its\ncondensed phase, the latter reacting to an external uniform magnetic field. The\ntarget is achieved introducing a new unitary translation operator transforming\neigenstates into a new set of eigenstates having different total linear\nmomentum. This new quantum representation solves the problem of calculating the\nmagnetic response of quantum eigenstates of finite or either infinite periodic\nsystems to uniform magnetic fields, where equivalence between the customarily\nused representation and the new representation has been made.",
        "category": "cond-mat"
    },
    {
        "text": "Tunable-range, photon-mediated atomic interactions in multimode cavity\n  QED: Optical cavity QED provides a platform with which to explore quantum\nmany-body physics in driven-dissipative systems. Single-mode cavities provide\nstrong, infinite-range photon-mediated interactions among intracavity atoms.\nHowever, these global all-to-all couplings are limiting from the perspective of\nexploring quantum many-body physics beyond the mean-field approximation. The\npresent work demonstrates that local couplings can be created using multimode\ncavity QED. This is established through measurements of the threshold of a\nsuperradiant, self-organization phase transition versus atomic position.\nSpecifically, we experimentally show that the interference of near-degenerate\ncavity modes leads to both a strong and tunable-range interaction between\nBose-Einstein condensates (BECs) trapped within the cavity. We exploit the\nsymmetry of a confocal cavity to measure the interaction between real BECs and\ntheir virtual images without unwanted contributions arising from the merger of\nreal BECs. Atom-atom coupling may be tuned from short range to long range. This\ncapability paves the way toward future explorations of exotic, strongly\ncorrelated systems such as quantum liquid crystals and driven-dissipative spin\nglasses.",
        "category": "cond-mat"
    },
    {
        "text": "Thin film modeling of crystal dissolution and growth in confinement: We present a continuum model describing dissolution and growth of a crystal\ncontact confined against a substrate. Diffusion and hydrodynamics in the liquid\nfilm separating the crystal and the substrate are modeled within the\nlubrication approximation. The model also accounts for the disjoining pressure\nand surface tension. Within this framework, we obtain evolution equations which\ngovern the non-equilibrium dynamics of the crystal interface. Based on this\nmodel, we explore the problem of dissolution under an external load, known as\npressure solution. We find that in steady-state, diverging (power-law)\ncrystal-surface repulsions lead to flat contacts with a monotonic increase of\nthe dissolution rate as a function of the load. Forces induced by viscous\ndissipation then surpass those due to disjoining pressure at large enough\nloads. In contrast, finite repulsions (exponential) lead to sharp pointy\ncontacts with a dissolution rate independent on the load and on the liquid\nviscosity. Ultimately, in steady-state the crystal never touches the substrate\nwhen pressed against it, independently from the nature of the crystal-surface\ninteraction due to the combined effects of viscosity and surface tension.",
        "category": "cond-mat"
    },
    {
        "text": "Real spin glasses relax slowly in the shade of hierarchical trees: The Parisi solution of the mean-field spin glass has been widely accepted and\ncelebrated. Its marginal stability in 3d and its complexity however raised the\nquestion of its relevance to real spin glasses. This paper gives a short\noverview of the important experimental results which could be understood within\nthe mean-field solution. The existence of a true phase transition and the\nparticular behaviour of the susceptibility below the freezing temperature,\npredicted by the theory, are clearly confirmed by the experimental results. The\nbehaviour of the complex order parameter and of the Fluctuation Dissipation\nratio are in good agreement with results of spontaneous noise measurements. The\nvery particular ultrametric symmetry, the key feature of the theory, provided\nus with a simple description of the rejuvenation and memory effects observed in\nexperiment. Finally, going a step beyond mean-field, the paper shortly\ndiscusses new analyses in terms of correlated domains characterized by their\nlength scales, as well as new experiments on superspin glasses which compare\nwell with recent theoretical simulations.",
        "category": "cond-mat"
    },
    {
        "text": "Frustration -- Exactly Solved Frustrated Models: After a short introduction on frustrated spin systems, we study in this\nchapter several two-dimensional frustrated Ising spin systems which can be\nexactly solved by using vertex models. We show that these systems contain most\nof the spectacular effects due to the frustration: high ground-state\ndegeneracy, existence of several phases in the ground-state phase diagram,\nmultiple phase transitions with increasing temperature, reentrance, disorder\nlines, partial disorder at equilibrium. Evidences of such effects in non\nsolvable models are also shown and discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Higher-Order Results for the Relation between Channel Conductance and\n  the Coulomb Blockade for Two Tunnel-Coupled Quantum Dots: We extend earlier results on the relation between the dimensionless tunneling\nchannel conductance $g$ and the fractional Coulomb blockade peak splitting $f$\nfor two electrostatically equivalent dots connected by an arbitrary number\n$N_{\\text{ch}}$ of tunneling channels with bandwidths $W$ much larger than the\ntwo-dot differential charging energy $U_{2}$. By calculating $f$ through second\norder in $g$ in the limit of weak coupling ($g \\rightarrow 0$), we illuminate\nthe difference in behavior of the large-$N_{\\text{ch}}$ and\nsmall-$N_{\\text{ch}}$ regimes and make more plausible extrapolation to the\nstrong-coupling ($g \\rightarrow 1$) limit. For the special case of\n$N_{\\text{ch}}=2$ and strong coupling, we eliminate an apparent ultraviolet\ndivergence and obtain the next leading term of an expansion in $(1-g)$. We show\nthat the results we calculate are independent of such band structure details as\nthe fraction of occupied fermionic single-particle states in the weak-coupling\ntheory and the nature of the cut-off in the bosonized strong-coupling theory.\nThe results agree with calculations for metallic junctions in the\n$N_{\\text{ch}} \\rightarrow \\infty$ limit and improve the previous good\nagreement with recent two-channel experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Thermal generation, manipulation and detection of skyrmions: Recent years have witnessed significant progresses in realizing skyrmions in\nchiral magnets1-4 and asymmetric magnetic multilayers5-13, as well as their\nelectrical manipulation2,7,8,10. Equally important, thermal generation,\nmanipulation and detection of skyrmions can be exploited for prototypical new\narchitecture with integrated computation14 and energy harvesting15. It has yet\nto verify if skyrmions can be purely generated by heating16,17, and if their\nresultant direction of motion driven by temperature gradients follows the\ndiffusion or, oppositely, the magnonic spin torque17-21. Here, we address these\nimportant issues in microstructured devices made of multilayers:\n(Ta_CoFeB_MgO)15, (Pt_CoFeB_MgO_Ta)15 and (Pt_Co_Ta)15 integrated with on-chip\nheaters, by using a full-field soft X-ray microscopy. The thermal generation of\ndensely packed skyrmions is attributed to the low energy barrier at the device\nedge, together with the thermally induced morphological transition from stripe\ndomains to skyrmions. The unidirectional diffusion of skyrmions from the hot\nregion towards the cold region is experimentally observed. It can be\ntheoretically explained by the combined contribution from repulsive forces\nbetween skyrmions, and thermal spin-orbit torques in competing with magnonic\nspin torques17,18,20,21 and entropic forces22. These thermally generated\nskyrmions can be further electrically detected by measuring the accompanied\nanomalous Nernst voltages23. The on-chip thermoelectric generation,\nmanipulation and detection of skyrmions could open another exciting avenue for\nenabling skyrmionics, and promote interdisciplinary studies among spin\ncaloritronics15, magnonics24 and skyrmionics3,4,12.",
        "category": "cond-mat"
    },
    {
        "text": "Bound on annealing performance from stochastic thermodynamics, with\n  application to simulated annealing: Annealing is the process of gradually lowering the temperature of a system to\nguide it towards its lowest energy states. In an accompanying paper [Luo et al.\nPhys. Rev. E 108, L052105 (2023)], we derived a general bound on annealing\nperformance by connecting annealing with stochastic thermodynamics tools,\nincluding a speed-limit on state transformation from entropy production. We\nhere describe the derivation of the general bound in detail. In addition, we\nanalyze the case of simulated annealing with Glauber dynamics in depth. We show\nhow to bound the two case-specific quantities appearing in the bound, namely\nthe activity, a measure of the number of microstate jumps, and the change in\nrelative entropy between the state and the instantaneous thermal state, which\nis due to temperature variation. We exemplify the arguments by numerical\nsimulations on the SK model of spin-glasses.",
        "category": "cond-mat"
    },
    {
        "text": "Transient excitonic states in optically-pumped Dirac materials: overview\n  of recent work: Driven and non-equilibrium quantum states of matter have attracted growing\ninterest in both theoretical and experimental studies in condensed matter\nphysics. We review recent progress in realizing transient collective states in\ndriven or pumped Dirac materials (DMs). In particular, we focus on\noptically-pumped DMs which have been theoretically proposed as a promising\nplatform for observation of a transient excitonic instability.\n  Optical pumping combined with the linear (Dirac) dispersion of the electronic\nspectrum offers a knob for tuning the effective interaction between the\nphotoexcited electrons and holes, and thus provides a way of reducing the\ncritical coupling for excitonic instability. As a result, a transient excitonic\ncondensate could be achieved in a pumped DM while it is not feasible in\nequilibrium. We provide a unifying theoretical framework for describing\ntransient collective states in two- and three-dimensional DMs. We describe\nexperimental signatures of the transient excitonic state and summarize\nnumerical estimates of the magnitude of the effect, namely the size of the\ndynamically-induced excitonic gaps and the values of the critical temperatures\nfor several specific systems. We also discuss general guidelines for\nidentifying promising material candidates.Finally, we comment recent\nexperimental efforts in realizing transient excitonic condensate in pumped DMs\nand outline outstanding issues and possible future directions.",
        "category": "cond-mat"
    },
    {
        "text": "Tunnel-Junction Thermometry Down to Millikelvin Temperatures: We present a simple on-chip electronic thermometer with the potential to\noperate down to 1 mK. It is based on transport through a single normal-metal -\nsuperconductor tunnel junction with rapidly widening leads. The current through\nthe junction is determined by the temperature of the normal electrode that is\nefficiently thermalized to the phonon bath, and it is virtually insensitive to\nthe temperature of the superconductor, even when the latter is relatively far\nfrom equilibrium. We demonstrate here the operation of the device down to 7 mK\nand present a systematic thermal analysis.",
        "category": "cond-mat"
    },
    {
        "text": "Chemically Functionalized Semiconducting Carbon Nanotubes: Limits for\n  High Conductance Performance: We present a first-principles study of the electronic transport properties of\nmicrometer long semiconducting CNTs randomly covered with carbene functional\ngroups. Whereas prior studies suggested that metallic tubes are hardly affected\nby such addends, we show here that the conductance of semiconducting tubes with\nstandard diameter is on the contrary severely damaged. The configurational\naveraged conductance as a function of tube diameter and with a coverage of up\nto one hundred functional groups is extracted. Our results indicate that the\nsearch for a conductance-preserving covalent functionalization route remains a\nchallenging issue.",
        "category": "cond-mat"
    },
    {
        "text": "$\u03b1$-FeSe as an orbital-selective incoherent metal: An LDA+DMFT\n  study: $\\alpha$-FeSe, a prototype iron-chalcogenide superconductor, shows clear\nsignatures of a strange incoherent normal state. Motivated thereby, we use\nLDA+DMFT to show how strong multi-band correlations generate a low-energy\npseudogap in the normal state, giving an incoherent metal in very good\nsemi-quantitative agreement with observations. We interpret our results in\nterms of $\\alpha$-FeSe being close to Mottness. A wide range of anomalous\nresponses in the \"normal\" state are consistently explained, lending strong\nsupport for this view. Implications for superconductivity arising from such an\nanomalous state are touched upon.",
        "category": "cond-mat"
    },
    {
        "text": "Huge (but finite) time scales in slow relaxations: beyond simple aging: Experiments performed in the last years demonstrated slow relaxations and\naging in the conductance of a large variety of materials. Here, we present\nexperimental and theoretical results for conductance relaxation and aging for\nthe case-study example of porous silicon. The relaxations are experimentally\nobserved even at room temperature over timescales of hours, and when a strong\nelectric field is applied for a time $t_w$, the ensuing relaxation depends on\n$t_w$. We derive a theoretical curve and show that all experimental data\ncollapse onto it with a single timescale as a fitting parameter. This timescale\nis found to be of the order of thousands of seconds at room temperature. The\ngeneric theory suggested is not fine-tuned to porous silicon, and thus we\nbelieve the results should be universal, and the presented method should be\napplicable for many other systems manifesting memory and other glassy effects.",
        "category": "cond-mat"
    },
    {
        "text": "Limitations of the two-media approach in calculating magneto-optical\n  properties of layered systems: It is shown that in polar geometry and normal incidence the 2x2 matrix\ntechnique - as discussed in detail in a preceeding paper [Phys. Rev. B 65,\n144448 (2002)] - accounts correctly for multiple reflections and optical\ninterferences, and reduces only in the case of a periodic sequence of identical\nlayers to the Fresnel formula of reflectivity, which in turn is the theoretical\nbasis of the two-media approach, widely used in the literature to compute\nmagneto-optical Kerr spectra. As a numerical example ab-initio calculations of\nthe optical constants for an fcc Pt semi-infinite bulk using the spin-polarized\nrelativistic screened Korringa-Kohn-Rostoker method show very good agreement\nwith experimental data.",
        "category": "cond-mat"
    },
    {
        "text": "Ferromagnetic exchange, spin-orbit coupling and spiral magnetism at the\n  LaAlO_3/SrTiO_3 interface: The electronic properties of the polar interface between insulating oxides is\na subject of great current interest. An exciting new development is the\nobservation of robust magnetism at the interface of two non-magnetic materials\nLaAlO_3 (LAO) and SrTiO_3 (STO). Here we present a microscopic theory for the\nformation and interaction of local moments, which depends on essential features\nof the LAO/STO interface. We show that correlation-induced moments arise due to\ninterfacial splitting of orbital degeneracy. We find that gate-tunable Rashba\nspin-orbit coupling at the interface influences the exchange interaction\nmediated by conduction electrons. We predict that the zero-field ground state\nis a long-wavelength spiral and show that its evolution in an external field\naccounts semi-quantitatively for torque magnetometry data. Our theory describes\nqualitative aspects of the scanning SQUID measurements and makes several\ntestable predictions for future experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Modelling a suspended nanotube oscillator: We present a general study of oscillations in suspended one-dimensional\nelastic systems clamped at each end, exploring a wide range of slack (excess\nlength) and downward external forces. Our results apply directly to recent\nexperiments in nanotube and silicon nanowire oscillators. We find the behavior\nto simplify in three well-defined regimes which we present in a dimensionless\nphase diagram. The frequencies of vibration of such systems are found to be\nextremely sensitive to slack.",
        "category": "cond-mat"
    },
    {
        "text": "Discovering Strongly Correlated Quantum Spin Liquid: Strongly correlated Fermi systems are among the most intriguing and\nfundamental systems in physics. We show that the herbertsmithite ZnCu3(OH)6Cl2\ncan be viewed as a new type of strongly correlated electrical insulator that\npossesses properties of heavy-fermion metals with one exception: it resists the\nflow of electric charge. We demonstrate that herbertsmithite's low temperature\nproperties are defined by a strongly correlated quantum spin liquid made with\nsuch hypothetic particles as fermionic spinons which carry spin 1/2 and no\ncharge. Our calculations of its thermodynamic and relaxation properties are in\ngood agreement with recent experimental facts and allow us to reveal their\nscaling behavior which strongly resembles that observed in heavy-fermion\nmetals. Analysis of the dynamic magnetic susceptibility of strongly correlated\nFermi systems suggests that there exist at least two types of its scaling.",
        "category": "cond-mat"
    },
    {
        "text": "Magnon Wave-function and Impurity Effects in S=1 Antiferromagnetic\n  Chains: A Large-n Approach: A large-n approximation to the S=1 antiferromagnetic chain, using the\nsymmetric tensor representation and its conjugate, is developed to order 1/n in\norder to calculate the magnon wave-function and to study the effect of\nmodifying the exchange coupling from J to J' on a single link. It is shown that\na magnon boundstate exists below the Haldane gap for arbitrarily small negative\nJ'-J but only above a certain critical value of J'-J for positive values. In\nthe former case the binding energy vanishes as the square of (J-J').",
        "category": "cond-mat"
    },
    {
        "text": "Absence of disordered Thouless pumps at finite frequency: A Thouless pump is a slowly driven one-dimensional band insulator which pumps\ncharge at a quantised rate. Previous work showed that pumping persists in\nweakly disordered chains, and separately in clean chains at finite drive\nfrequency. We study the interplay of disorder and finite frequency, and show\nthat the pump rate always decays to zero due to non-adiabatic transitions\nbetween the instantaneous eigenstates. However, the decay is slow, occurring on\na time-scale that is exponentially large in the period of the drive. In the\nadiabatic limit, the band gap in the instantaneous spectrum closes at a\ncritical disorder strength above which pumping ceases. We predict the scaling\nof the pump rate around this transition from a model of scattering between rare\nstates near the band edges. Our predictions can be experimentally tested in\nultracold atomic and photonic platforms.",
        "category": "cond-mat"
    },
    {
        "text": "Learning and predicting time series by neural networks: Artificial neural networks which are trained on a time series are supposed to\nachieve two abilities: firstly to predict the series many time steps ahead and\nsecondly to learn the rule which has produced the series. It is shown that\nprediction and learning are not necessarily related to each other. Chaotic\nsequences can be learned but not predicted while quasiperiodic sequences can be\nwell predicted but not learned.",
        "category": "cond-mat"
    },
    {
        "text": "Improved Thin Film Quality and Photoluminescence of N-Doped Epitaxial\n  Germanium-on-Silicon using MOCVD: Ge-on-Si structures in-situ doped with phosphorus or arsenic via metal\norganic chemical vapor deposition (MOCVD) were investigated. Surface roughness,\nstrain, threading dislocation desnity, Si-Ge interdiffusion, dopant diffusion,\nand photoluminescence were characterized to study the impacts of defect\nannealing and Si substrate offcut effects on the Ge film quality and most\nimportantly, the light emission properties. All samples have a smooth surface\n(roughness < 1.5 nm), and the Ge films have a small tensile strain of 0.2%.\nAs-grown P and As-doped Ge films have threading dislocaiton densities from\n2.8e8 to 1.1e9 cm^(-2) without defect annealing. With thermal cycling, these\nvalues reduced to 1-1.5e8 cm^(-2). The six degree offcut of the Si substrate\nwas shown to have little impact. In contrast to delta doping, the out-diffusion\nof dopants has been successfully suppressed to retain the doping concentration\nupon defect annealing. However, the photoluminescence intensity decreases\nmostly due to Si-Ge interdiffusion, which also causes a blue-shift in the\nemission wavelength. Compared to a benckmarking sample from the first Ge laser\nwork doped by delta doping method in 2012, the as-grown P or As-doped Ge films\nhave similar photoluminescence intensity at a 25% doping concentration and\nsmoother surface, which are promising for Ge lasers with better light emission\nefficiencies.",
        "category": "cond-mat"
    },
    {
        "text": "Nonlinear electric transport in graphene with magnetic disorder: The influence of magnetic impurities on the transport properties of graphene\nis investigated in the regime of strong applied electric fields. As a result of\nelectron-hole pair creation, the response becomes nonlinear and dependent on\nthe magnetic polarization. In the paramagnetic phase, time reversal symmetry is\nstatistically preserved, and transport properties are similar to the clean\ncase. At variance, in the antiferromagnetic phase, the system undergoes a\ntransition between a superdiffusive to a subdiffusive spreading of a wave\npacket, signaling the development of localized states. This critical regime is\ncharacterized by the appearance of electronic states with a multifractal\ngeometry near the gap. The local density of states concentrates in large\npatches having a definite charge-spin correlation. In this state, the\nconductivity tends to half the minimum conductivity of clean graphene.",
        "category": "cond-mat"
    },
    {
        "text": "Rigorous proof of a phase transition of parallelizability in a\n  one-dimensional structure assembly: In this paper, we prove the existence of a phase transition of\nparallelizability in the assembly of one-dimensional chains. By introducing the\nparallel efficiency that measures how efficiently the parallel assembly works,\nthe parallelizable phase is defined by its positive value. The\nparallelizable/unparallelizable transition is then identified by the\nnon-analytic change in the parallel efficiency from a positive value to zero.\nBy evaluating the parallel efficiency on each side of the transition point, we\nshow the existence of a phase transition in this system.",
        "category": "cond-mat"
    },
    {
        "text": "Thermodynamics of Antiferromagnetic Solids in Magnetic Fields: We analyze the thermodynamic properties of antiferromagnetic solids subjected\nto a combination of mutually orthogonal uniform magnetic and staggered fields.\nLow-temperature series for the pressure, order parameter and magnetization up\nto two-loop order in the effective expansion are established. We evaluate the\nself-energy and the dispersion relation of the dressed magnons in order to\ndiscuss the impact of spin-wave interactions on thermodynamic observables.",
        "category": "cond-mat"
    },
    {
        "text": "Remanence effects in the electrical resistivity of spin glasses: We have measured the low temperature electrical resistivity of Ag : Mn\nmesoscopic spin glasses prepared by ion implantation with a concentration of\n700 ppm. As expected, we observe a clear maximum in the resistivity (T ) at a\ntemperature in good agreement with theoretical predictions. Moreover, we\nobserve remanence effects at very weak magnetic fields for the resistivity\nbelow the freezing temperature Tsg: upon Field Cooling (fc), we observe clear\ndeviations of (T ) as compared with the Zero Field Cooling (zfc); such\ndeviations appear even for very small magnetic fields, typically in the Gauss\nrange. This onset of remanence for very weak magnetic fields is reminiscent of\nthe typical signature on magnetic susceptibility measurements of the spin glass\ntransition for this generic glassy system.",
        "category": "cond-mat"
    },
    {
        "text": "Anisotropy of graphite optical conductivity: The graphite conductivity is evaluated for frequencies between\n  0.1 eV, the energy of the order of the electron-hole overlap, and 1.5 eV, the\nelectron nearest hopping energy. The in-plane conductivity per single atomic\nsheet is close to the universal graphene conductivity $e^2/4\\hbar$ and,\nhowever, contains a singularity conditioned by peculiarities of the electron\ndispersion. The conductivity is less in the $c-$direction by the factor of the\norder of 0.01 governed by electron hopping in this direction.",
        "category": "cond-mat"
    },
    {
        "text": "Persistent photovoltage in methylammonium lead iodide perovskite solar\n  cells: Open circuit voltage decay measurements are performed on methylammonium lead\niodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier\nrecombination dynamics. The measurements are compared to the two reference\npolymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and\nPTB7:PC70BM blends. In the perovskite devices, two very different time domains\nof the voltage decay are found, with a first drop on a short time scale that is\nsimilar to the organic solar cells. However, two major differences are also\nobserved. 65-70% of the maximum photovoltage persists on much longer\ntimescales, and the recombination dynamics are dependent on the illumination\nintensity.",
        "category": "cond-mat"
    },
    {
        "text": "Ultrafast Charge Migration in XUV Photoexcited Phenylalanine: a\n  First-Principles Study Based on Real-Time Nonequilibrium Green's Functions: The early stage density oscillations of the electronic charge in molecules\nirradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond\ntimescales. This ultrafast charge migration process is a central topic in\nattoscience as it dictates the relaxation pathways of the molecular structure.\nA predictive quantum theory of ultrafast charge migration should incorporate\nthe atomistic details of the molecule, electronic correlations and the\nmultitude of ionization channels activated by the broad-bandwidth XUV pulse. In\nthis work we propose a first-principles Non Equilibrium Green's Function method\nfulfilling all three requirements, and apply it to a recent experiment on the\nphotoexcited phenylalanine aminoacid. Our results show that dynamical\ncorrelations are necessary for a quantitative overall agreement with the\nexperimental data. In particular, we are able to capture the transient\noscillations at frequencies 0.15PHz and 0.30PHz in the hole density of the\namine group, as well as their suppression and the concomitant development of a\nnew oscillation at frequency 0.25PHz after about 14 femtoseconds.",
        "category": "cond-mat"
    },
    {
        "text": "Noise Measurements of High-Speed, Light-Emitting GaN Resonant-Tunneling\n  Diodes: We report here the first RF noise measurements on two designs of n-doped\nGaN/AlN double-barrier resonant tunneling diodes (RTDs), each having a\nroom-temperature negative differential resistance (NDR) and also strong near-UV\nlight emission. The measurements are made with a standard, un-isolated RF\nreceiver and calibration is made using a substitution-resistor/hot-cold\nradiometric technique which works in the positive differential resistance (PDR)\nregion but not the NDR region. A high-quality InGaAs/AlAs double-barrier RTD is\nused as a control sample and displays shot noise suppression down to\n$\\Gamma\\approx$0.5 in the PDR region, as expected. The GaN/AlN RTDs display\nboth shot-noise enhancement and suppression in the PDR regions, but no obvious\nsign of sudden shot-noise enhancement in the threshold bias region of light\nemission. This supports the hypothesis that the holes required for light\nemission are created by electronic (Zener) interband tunneling, not impact\nionization. Further the minimum shot-noise factor of $\\Gamma\\sim$ 0.34 suggests\nthat the GaN/AlN RTDs are acting like triple-barrier devices.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum chaos on a critical Fermi surface: We compute parameters characterizing many-body quantum chaos for a critical\nFermi surface without quasiparticle excitations. We examine a theory of $N$\nspecies of fermions at non-zero density coupled to a $U(1)$ gauge field in two\nspatial dimensions, and determine the Lyapunov rate and the butterfly velocity\nin an extended random-phase approximation. The thermal diffusivity is found to\nbe universally related to these chaos parameters i.e. the relationship is\nindependent of $N$, the gauge coupling constant, the Fermi velocity, the Fermi\nsurface curvature, and high energy details.",
        "category": "cond-mat"
    },
    {
        "text": "Effects of interactions on Bose-Einstein condensation of an atomic gas: The phase transition to a Bose-Einstein condensate is unusual in that it is\nnot necessarily driven by inter-particle interactions but can occur in an ideal\ngas as a result of a purely statistical saturation of excited states. However,\ninteractions are necessary for any system to reach thermal equilibrium and so\nare required for condensation to occur in finite time. In this Chapter we\nreview the role of interactions in Bose-Einstein condensation, covering both\ntheory and experiment. We focus on measurements performed on harmonically\ntrapped ultracold atomic gases, but also discuss how these results relate to\nthe uniform-system case, which is more theoretically studied and also more\nrelevant for other experimental systems.\n  We first consider interaction strengths for which the system can be\nconsidered sufficiently close to equilibrium to measure thermodynamic\nbehaviour. In particular we discuss the effects of interactions both on the\nmechanism of condensation (namely the saturation of the excited states) and on\nthe critical temperature at which condensation occurs. We then discuss in more\ndetail the conditions for the equilibrium thermodynamic measurements to be\npossible, and the non-equilibrium phenomena that occur when these conditions\nare controllably violated by tuning the strength of interactions in the gas.",
        "category": "cond-mat"
    },
    {
        "text": "Room-temperature multiferroic hexagonal LuFeO$_3$ films: The crystal and magnetic structures of single-crystalline hexagonal LuFeO$_3$\nfilms have been studied using x-ray, electron and neutron diffraction methods.\nThe polar structure of these films are found to persist up to 1050 K; and the\nswitchability of the polar behavior is observed at room temperature, indicating\nferroelectricity. An antiferromagnetic order was shown to occur below 440 K,\nfollowed by a spin reorientation resulting in a weak ferromagnetic order below\n130 K. This observation of coexisting multiple ferroic orders demonstrates that\nhexagonal LuFeO$_3$ films are room-temperature multiferroics.",
        "category": "cond-mat"
    },
    {
        "text": "Polaritons are Not Weakly Interacting: Direct Measurement of the\n  Polariton-Polariton Interaction Strength: Exciton-polaritons in a microcavity are composite two-dimensional bosonic\nquasiparticles, arising from the strong coupling between confined light modes\nin a resonant planar optical cavity and excitonic transitions, typically using\nexcitons in semiconductor quantum wells (QWs) placed at the antinodes of the\nsame cavity. Quantum phenomena such as Bose-Einstein condensation (BEC),\nquantized vortices, and macroscopic quantum states have been reported at\ntemperatures from tens of Kelvin up to room temperatures, and polaritonic\ndevices such as spin switches \\cite{Amo2010} and optical transistors have also\nbeen reported. Many of these effects of exciton-polaritons depend crucially on\nthe polariton-polariton interaction strength. Despite the importance of this\nparameter, it has been difficult to make an accurate experimental measurement,\nmostly because of the difficulty of determining the absolute densities of\npolaritons and bare excitons. Here we report the direct measurement of the\npolariton-polariton interaction strength in a very high-Q microcavity\nstructure. By allowing polaritons to propagate over 40 $\\mu$m to the center of\na laser-generated annular trap, we are able to separate the polariton-polariton\ninteractions from polariton-exciton interactions. The interaction strength is\ndeduced from the energy renormalization of the polariton dispersion as the\npolariton density is increased, using the polariton condensation as a benchmark\nfor the density. We find that the interaction strength is about two orders of\nmagnitude larger than previous theoretical estimates, putting polaritons\nsquarely into the strongly-interacting regime. When there is a condensate, we\nsee a sharp transition to a different dependence of the renormalization on the\ndensity, which is evidence of many-body effects.",
        "category": "cond-mat"
    },
    {
        "text": "Kramers-Wannier Duality and Random Bond Ising Model: We present a new combinatorial approach to the Ising model incorporating\narbitrary bond weights on planar graphs. In contrast to existing methodologies,\nthe exact free energy is expressed as the determinant of a set of ordered and\ndisordered operators defined on vertices and dual vertices respectively,\nthereby explicitly demonstrating the Kramers-Wannier duality. The implications\nof our derived formula for the random bond Ising model are further elucidated.",
        "category": "cond-mat"
    },
    {
        "text": "First-principles DFT+\\emph{U} study of structural and electronic\n  properties of PbCrO$_{3}$: We have performed a systematic first-principles investigation to calculate\nthe structural, electronic, and magnetic properties of PbCrO$_{3}$, CrPbO$_{3}$\nas well as their equiproportional combination. The local density approximation\n(LDA)$+U$ and the generalized gradient approximation$+U$ theoretical formalisms\nhave been used to account for the strong on-site Coulomb repulsion among the\nlocalized Cr 3d electrons. By choosing the Hubbard \\emph{U} parameter around 4\neV, ferromagnetic, and/or antiferromagnetic ground states can be achieved and\nour calculated lattice constants, bulk moduli, and equation of states are in\ngood agreement with recent experiments [W. Xiao \\emph{et al.}, PNAS\n\\textbf{107}, 14026 (2010)]. The bonding nature of B$-$O bonds in these\nABO$_{3}$ compounds exhibit evident covalent character and our electron\ntransferring study indicates that the ionicity shows decreasing trend with\nincreasing fraction of CrO$_{6/2}$ octahedron within the\nPbCrO$_{3}$-CrPbO$_{3}$ random compounds. The lengthes of B$-$O bonds determine\ntheir lattice parameters, thus, clearly indicates that the abnormally large\nvolume and compressibility is due to the contain of CrPbO$_{3}$ in the\nexperimental sample and the transition of PbO$_{6/2}$ octahedron to CrO$_{6/2}$\nupon compression.",
        "category": "cond-mat"
    },
    {
        "text": "Kondo effect in \"bad metals\": We study the low-temperature properties of a Kondo lattice using the large-N\nformalism. For a singular density of conduction states (DOS), we generalize the\nsingle-impurity result of Withoff and Fradkin: the strong-coupling fixed point\nbecomes irrelevant if the DOS vanishes at the Fermi level E_F. However, for E_F\nclose enough to the singularity, and close to half-filling, the Kondo\ntemperature, $T_K$, can become much smaller than the characteristic Fermi\nliquid scale. At T=0, a meta-magnetic transition occurs at the critical\nmagnetic field H_c ~ (k_B/mu_B) T_K. Our results provide a qualitative\nexplanation for the behavior of the YbInCu_4 compound below the valence-change\ntransition.",
        "category": "cond-mat"
    },
    {
        "text": "Contrary Effect of B and N Doping into Graphene and Graphene Oxide\n  Heterostructures with MoS$_2$ on Interface Function and Hydrogen Evolution: Molybdenum disulfide (MoS$_2$) attracts attention as a high efficient and low\ncost photocatalyst for hydrogen production, but suffers from low conductance\nand high recombination rate of photo-generated charge carriers. In this work,\nwe investigate the MoS$_2$ heterostructures with graphene variants (GVs),\nincluding graphene, graphene oxide, and their boron- and nitrogen-doped\nvariants, by using first-principles calculations. Systematic comparison between\ngraphene and graphene oxide composites is performed, and contrary effect of B\nand N doping on interface function and hydrogen evolution is clarified. We find\nthat upon the formation of the interfaces some amount of electronic charge\ntransfers from the GV side to the MoS$_2$ layer, inducing the creation of\ninterface dipole and the reduction of work function, which is more pronounced\nin the graphene oxide composites. Moreover, our results reveal that N doping\nenhances the interface functions by forming donor-type interface states,\nwhereas B doping reduces those functions by forming acceptor-type interface\nstates. However, the B-doped systems exhibit lower Gibbs free energy difference\nfor hydrogen adsorption on GV side than the N-doped systems, which deserves\nmuch consideration in the design of new functional photocatalysts.",
        "category": "cond-mat"
    },
    {
        "text": "Gas sensing technologies -- status, trends, perspectives and novel\n  applications: The strong, continuous progresses in gas sensors and electronic noses\nresulted in improved performance and enabled an increasing range of\napplications with large impact on modern societies, such as environmental\nmonitoring, food quality control and diagnostics by breath analysis. Here we\nreview this field with special attention to established and emerging approaches\nas well as the most recent breakthroughs, challenges and perspectives. In\nparticular, we focus on (1) the transduction principles employed in different\narchitectures of gas sensors, analysing their advantages and limitations; (2)\nthe sensing layers including recent trends toward nanostructured,\nlow-dimensional and composite materials; (3) advances in signal processing\nmethodologies, including the recent advent of artificial neural networks.\nFinally, we conclude with a summary on the latest achievements and trends in\nterms of applications.",
        "category": "cond-mat"
    },
    {
        "text": "Mechanical fluctuations suppress the threshold of soft-glassy solids :\n  the secular drift scenario: We propose a dynamical mechanism leading to the fluidization of soft-glassy\namorphous mate-rial driven below the yield-stress by external mechanical\nfluctuations. The model is based on the combination of memory effect and\nnon-linearity, leading to an accumulation of tiny effects over a long-term. We\ntest this scenario on a granular packing driven mechanically below the Coulomb\nthreshold. We bring evidences for an effective viscous response directly\nrelated to small stress modulations in agreement with the theoretical\nprediction of a generic secular drift.",
        "category": "cond-mat"
    },
    {
        "text": "Impressive optoelectronic and thermoelectric properties of\n  two-dimensional XI$_2$ (X=Sn, Si): a first principle study: Two-dimensional (2D) metal halides have received more attention because of\ntheir electronic and optoelectronic properties. Recently, researchers are\ninterested to investigate the thermoelectric properties of metal halide\nmonolayers because of their ultralow lattice conductivity, high Seebeck\ncoefficient and figure of merit. Here, we have investigated thermoelectric and\noptoelectronic properties of XI$_2$ (X=Sn and Si) monolayers with the help of\ndensity functional theory and Boltzmann transport equation. The structural\nparameters have been optimized with relaxation of atomic positions. Excellent\nthermoelectric and optical properties have been obtained for both SnI$_2$ and\nSiI$_2$ monolayers. For SnI$_2$ an indirect bandgap of 2.06 eV was observed and\nthe absorption peak was found at 4.68 eV. For this the highest ZT value of 0.84\nfor p-type doping at 600K has been calculated. Similarly, for SiI$_2$ a\ncomparatively low indirect bandgap of 1.63 eV was observed, and the absorption\npeak was obtained at 4.86 eV. The calculated ZT product for SiI$_2$ was 0.87 at\n600K. Both the crystals having high absorbance and ZT value suggest that they\ncan be promising candidates for optoelectronic and thermoelectric devices.",
        "category": "cond-mat"
    },
    {
        "text": "Stabilizing fluctuating spin-triplet superconductivity in graphene via\n  induced spin-orbit coupling: A recent experiment showed that proximity induced Ising spin-orbit coupling\nenhances the spin-triplet superconductivity in Bernal bilayer graphene. Here,\nwe show that, due to the nearly perfect spin rotation symmetry of graphene, the\nfluctuations of the spin orientation of the triplet order parameter suppress\nthe superconducting transition to nearly zero temperature. Our analysis shows\nthat both Ising spin-orbit coupling and in-plane magnetic field can eliminate\nthese low-lying fluctuations and can greatly enhance the transition\ntemperature, consistent with the recent experiment. Our model also suggests the\npossible existence of a phase at small anisotropy and magnetic field which\nexhibits quasi-long-range ordered spin-singlet charge 4e superconductivity,\neven while the triplet 2e superconducting order only exhibits short-ranged\ncorrelations. Finally, we discuss relevant experimental signatures.",
        "category": "cond-mat"
    },
    {
        "text": "Many-body Multifractality throughout Bosonic Superfluid and Mott\n  Insulator Phases: We demonstrate many-body multifractality of the Bose-Hubbard Hamiltonian's\nground state in Fock space, for arbitrary values of the interparticle\ninteraction. Generalized fractal dimensions unambiguously signal, even for\nsmall system sizes, the emergence of a Mott insulator, that cannot, however, be\nnaively identified with a localized phase in Fock space. We show that the\nscaling of the derivative of any generalized fractal dimension with respect to\nthe interaction strength encodes the critical point of the superfluid to Mott\ninsulator transition, and provides an efficient way to accurately estimate its\nposition. We further establish that the transition can be quantitatively\ncharacterized by one single wavefunction amplitude from the exponentially large\nFock space.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamical dimer correlations at bipartite and non-bipartite\n  Rokhsar-Kivelson points: We determine the dynamical dimer correlation functions of quantum dimer\nmodels at the Rokhsar-Kivelson point on the bipartite square and cubic lattices\nand the non-bipartite triangular lattice. Based on an algorithmic idea by\nHenley, we simulate a stochastic process of classical dimer configurations in\ncontinuous time and perform a stochastic analytical continuation to obtain the\ndynamical correlations in momentum space and the frequency domain. This\napproach allows us to observe directly the dispersion relations and the\nevolution of the spectral intensity within the Brillouin zone beyond the\nsingle-mode approximation. On the square lattice, we confirm analytical\npredictions related to soft modes close to the wavevectors (pi,pi) and (pi,0)\nand further reveal the existence of shadow bands close to the wavevector (0,0).\nOn the cubic lattice the spectrum is also gapless but here only a single soft\nmode at (pi,pi,pi) is found, as predicted by the single mode approximation. The\nsoft mode has a quadratic dispersion at very long wavelength, but crosses over\nto a linear behavior very rapidly. We believe this to be the remnant of the\nlinearly dispersing \"photon\" of the Coulomb phase. Finally the triangular\nlattice is in a fully gapped liquid phase where the bottom of the dimer\nspectrum exhibits a rich structure. At the M point the gap is minimal and the\nspectral response is dominated by a sharp quasiparticle peak. On the other\nhand, at the X point the spectral function is much broader. We sketch a\npossible explanation based on the crossing of the coherent dimer excitations\ninto the two-vison continuum.",
        "category": "cond-mat"
    },
    {
        "text": "Rotation of the dislocation grid in multilayer FeSe films and\n  visualization of electronic nematic domains via orbital-selective tunneling: Understanding the interplay of structural and electronic symmetry breaking in\nFe-based high temperature superconductors remains of high interest. In this\nwork we grow strain-patterned multilayer FeSe thin films in a range of\nthicknesses using molecular beam epitaxy. We study the formation of electronic\nnematic domains and spatially-varying strain using scanning tunneling\nmicroscopy and spectroscopy. We directly visualize the formation of edge\ndislocations that give rise to a two-dimensional edge dislocation network in\nthe films. Interestingly, we observe a 45 degree in-plane rotation of the\ndislocation network as a function of film thickness, yielding antisymmetric\nstrain along different directions. This results in different coupling ratios\nbetween electronic nematic domains and antisymmetric strain. Lastly, we are\nable to distinguish between different orthogonal nematic domains by revealing a\nsmall energy-dependent difference in differential conductance maps between the\ntwo regions. This could be explained by orbital-selective tip-sample tunneling.\nOur observations bring new insights into the dislocation network formation in\nepitaxial thin films and provide another nanoscale tool to explore electronic\nnematicity in Fe-based superconductors.",
        "category": "cond-mat"
    },
    {
        "text": "Ultracold atomic Bose and Fermi spinor gases in optical lattices: We investigate magnetic properties of Mott-insulating phases of ultracold\nBose and Fermi spinor gases in optical lattices. We consider in particular the\nF=2 Bose gas, and the F=3/2 and F=5/2 Fermi gases. We derive effective spin\nHamiltonians for one and two atoms per site and discuss the possibilities of\nmanipulating the magnetic properties of the system using optical Feshbach\nresonances. We discuss low temperature quantum phases of a 87Rb gas in the F=2\nhyperfine state, as well as possible realizations of high spin Fermi gases with\neither 6Li or 132Cs atoms in the F=3/2 state, and with 173Yb atoms in the F=5/2\nstate.",
        "category": "cond-mat"
    },
    {
        "text": "Clustering and fluidization in a one-dimensional granular system:\n  molecular dynamics and direct-simulation Monte Carlo method: We study a 1-D granular gas of point-like particles not subject to gravity\nbetween two walls at temperatures T_left and T_right. The system exhibits two\ndistinct regimes, depending on the normalized temperature difference Delta =\n(T_right - T_left)/(T_right + T_left): one completely fluidized and one in\nwhich a cluster coexists with the fluidized gas. When Delta is above a certain\nthreshold, cluster formation is fully inhibited, obtaining a completely\nfluidized state. The mechanism that produces these two phases is explained. In\nthe fluidized state the velocity distribution function exhibits peculiar\nnon-Gaussian features. For this state, comparison between integration of the\nBoltzmann equation using the direct-simulation Monte Carlo method and results\nstemming from microscopic Newtonian molecular dynamics gives good coincidence,\nestablishing that the non-Gaussian features observed do not arise from the\nonset of correlations.",
        "category": "cond-mat"
    },
    {
        "text": "Hysteresis behavior of the anisotropic quantum Heisenberg model driven\n  by periodic magnetic field: Dynamic behavior of a quantum Heisenberg ferromagnet in the presence of a\nperiodically oscillating magnetic field has been analyzed by means of the\neffective field theory with two spin cluster. The dynamic equation of motion\nhas been constructed with the help of a Glauber type stochastic process and\nsolved for a simple cubic lattice. After the phase diagrams given, the behavior\nof the hysteresis loop area, coercive field and remanent magnetization with the\nanisotropy in the exchange interaction has been investigated in detail.\nEspecially, by comparing of the magnitudes of the hysteresis loop area in the\nhigh anisotropy limit (i.e. Ising model) and low anisotropy limit (i.e.\nisotropic Heisenberg model), detailed description of the hysteresis loop area\nwith the anisotropy in the exchange interaction given. Some interesting\nfeatures have been obtained about this behavior as well as in phase diagrams\nsuch as tricritical points.",
        "category": "cond-mat"
    },
    {
        "text": "Non-linear Poisson-Boltzmann Theory for Swollen Clays: The non-linear Poisson-Boltzmann equation for a circular, uniformly charged\nplatelet, confined together with co- and counter-ions to a cylindrical cell, is\nsolved semi-analytically by transforming it into an integral equation and\nsolving the latter iteratively. This method proves efficient, robust, and can\nbe readily generalized to other problems based on cell models, treated within\nnon-linear Poisson-like theory. The solution to the PB equation is computed\nover a wide range of physical conditions, and the resulting osmotic equation of\nstate is shown to be in fair agreement with recent experimental data for\nLaponite clay suspensions, in the concentrated gel phase.",
        "category": "cond-mat"
    },
    {
        "text": "Robust entangling gate for capacitively coupled few-electron\n  singlet-triplet qubits: The search of a sweet spot, locus in qubit parameters where quantum control\nis first-order insensitive to noises, is key to achieve high-fidelity quantum\ngates. Efforts to search for such a sweet spot in conventional\ndouble-quantum-dot singlet-triplet qubits where each dot hosts one electron\n(\"two-electron singlet-triplet qubit\"), especially for two-qubit operations,\nhave been unsuccessful. Here we consider singlet-triplet qubits allowing each\ndot to host more than one electron, with a total of four electrons in the\ndouble quantum dots (\"four-electron singlet-triplet qubit\"). We theoretically\ndemonstrate, using configuration-interaction calculations, that sweet spots\nappear in this coupled qubit system. We further demonstrate that, under\nrealistic charge noise and hyperfine noise, two-qubit operation at the proposed\nsweet spot could offer gate fidelities ($\\sim99\\%$) that are higher than\nconventional two-electron singlet-triplet qubit system ($\\sim90\\%$). Our\nresults should facilitate realization of high-fidelity two-qubit gates in\nsinglet-triplet qubit systems.",
        "category": "cond-mat"
    },
    {
        "text": "Elasticity and melting of skyrmion flux lattices in p-wave\n  superconductors: We analytically calculate the energy, magnetization curves (B(H)), and\nelasticity of skyrmion flux lattices in p-wave superconductors near the lower\ncritical field H_c1, and use these results with the Lindemann criterion to\npredict their melting curve. In striking contrast to vortex flux lattices,\nwhich always melt at an external field H > H_c1, skyrmion flux lattices never\nmelt near H_c1. This provides a simple and unambiguous test for the presence of\nskyrmions.",
        "category": "cond-mat"
    },
    {
        "text": "Rational Approximations of Quasi-Periodic Problems via Projected Green's\n  Functions: We introduce the projected Green's function technique to study quasi-periodic\nsystems such as the Andre-Aubry-Harper (AAH) model and beyond. In particular,\nwe use projected Green's functions to construct a \"rational approximate\"\nsequence of transfer matrix equations consistent with quasi-periodic topology,\nwhere convergence of these sequences corresponds to the existence of extended\neigenfunctions. We motivate this framework by applying it to a few well studied\ncases such as the almost-Mathieu operator (AAH model), as well as more generic\nnon-dual models that challenge standard routines. The technique is flexible and\ncan be used to extract both analytic and numerical results, e.g. we\nanalytically extract a modified phase diagram for Liouville irrationals. As a\nnumerical tool, it does not require the fixing of boundary conditions and\ncircumvents a primary failing of numerical techniques in quasi-periodic\nsystems, extrapolation from finite size. Instead, it uses finite size scaling\nto define convergence bounds on the full irrational limit.",
        "category": "cond-mat"
    },
    {
        "text": "Voltage-dependent first-principles simulation of insertion of chloride\n  ions into Al/Al$_2$O$_3$ interfaces using the Quantum Continuum Approximation: Experiments have shown that pitting corrosion can develop in aluminum\nsurfaces at potentials $> -0.5$ V relative to the standard hydrogen electrode\n(SHE). Until recently, the onset of pitting corrosion in aluminum has not been\nrigorously explored at an atomistic scale because of the difficulty of\nincorporating a voltage into density functional theory (DFT) calculations. We\nintroduce the Quantum Continuum Approximation (QCA) which self-consistently\ncouples explicit DFT calculations of the metal-insulator and insulator-solution\ninterfaces to continuum Poisson-Boltzmann electrostatic distributions\ndescribing the bulk of the insulating region. By decreasing the number of atoms\nnecessary to explicitly simulate with DFT by an order of magnitude, QCA makes\nthe first-principles prediction of the voltage of realistic electrochemical\ninterfaces feasible. After developing this technique, we apply QCA to predict\nthe formation energy of chloride atoms inserting into oxygen vacancies in\nAl(111)/$\\alpha$-Al$_2$O$_3$ (0001) interfaces as a function of applied\nvoltage. We predict that chloride insertion is only favorable in systems with a\ngrain boundary in the Al$_2$O$_3$ for voltages $> -0.2$ V (SHE). Our results\nroughly agree with the experimentally demonstrated onset of corrosion,\ndemonstrating QCA's utility in modeling realistic electrochemical systems at\nreasonable computational cost.",
        "category": "cond-mat"
    },
    {
        "text": "Tsallis distributions and 1/f noise from nonlinear stochastic\n  differential equations: Probability distributions which emerge from the formalism of nonextensive\nstatistical mechanics have been applied to a variety of problems. In this paper\nwe unite modeling of such distributions with the model of widespread 1/f noise.\nWe propose a class of nonlinear stochastic differential equations giving both\nthe q-exponential or q-Gaussian distributions of signal intensity, revealing\nlong-range correlations and 1/f^beta behavior of the power spectral density.\nThe superstatistical framework to get 1/f^beta noise with q-exponential and\nq-Gaussian distributions of the signal intensity in is proposed, as well.",
        "category": "cond-mat"
    },
    {
        "text": "Topological Effect of Surface Plasmon Excitation in Gapped Isotropic\n  Topological Insulator Nanowires: We present a theoretical investigation of the surface plasmon (SP) at the\ninterface between topologically non-trivial cylindrical core and\ntopological-trivial surrounding material, from the axion electrodynamics and\nmodified constitutive relations. We find that the topological effect always\nleads to a red-shift of SP energy, while the energy red-shift decreases\nmonotonically as core diameter decreases. A qualitative picture based on\nclassical perturbation theory is given to explain these phenomena, from which\nwe also infer that in order to enhance the shift, the difference between the\ninverse of dielectric constants of two materials shall be increased. We also\nfind that the surrounding magnetic environment suppresses the topological\neffect. All these features can be well described by a simple ansatz surface\nwave, which is in good agreement with full electromagnetic eigenmodes. In\naddition, bulk plasmon energy at \\omega_{P}=17.5\\pm0.2eV for semiconducting\nBi2Se3 nanoparticle is observed from high-resolution Electron Energy Loss\nSpectrum Image measurements.",
        "category": "cond-mat"
    },
    {
        "text": "Building and Destroying Symmetry in 1-D Elastic Systems: Locally periodic rods, which show approximate invariance with respect to\ntranslations, are constructed by joining $N$ unit cells. The spectrum then\nshows a band spectrum. We then break the local periodicity by including one or\nmore defects in the system. When the defects follow a certain definite\nprescription, an analog of the Wannier-Stark ladders is gotten; when the\ndefects are random, an elastic rod showing Anderson localization is obtained.\nIn all cases experimental values match the theoretical predictions.",
        "category": "cond-mat"
    },
    {
        "text": "Random sequential adsorption of trimers and hexamers: Adsorption of trimers and hexamers built of identical spheres was studied\nnumerically using the Random Sequential Adsorption (RSA) algorithm. Particles\nwere adsorbed on a two dimensional, flat and homogeneous surface. Numerical\nsimulations allow to establish the maximal random coverage ratio, RSA kinetics\nas well as the Available Surface Function (ASF), which is crucial for\ndetermining kinetics of the adsorption process obtained experimentally.\nAdditionally, the density autocorrelation function was measured. All the\nresults were compared with previous results obtained for spheres, dimers and\ntetramers.",
        "category": "cond-mat"
    },
    {
        "text": "Charge carrier localisation in disordered graphene nanoribbons: We study the electronic properties of actual-size graphene nanoribbons\nsubjected to substitutional disorder particularly with regard to the\nexperimentally observed metal-insulator transition. Calculating the local, mean\nand typical density of states, as well as the time-evolution of the particle\ndensity we comment on a possible disorder-induced localisation of charge\ncarriers at and close to the Dirac point within a percolation transition\nscenario.",
        "category": "cond-mat"
    },
    {
        "text": "Large-scale simulation of adhesion dynamics for end-graphed polymers: The adhesion between a polymer melt and substrate is studied in the presence\nof chemically attached chains on the substrate surface. Extensive molecular\ndynamics simulations have been carried out to study the effect of temperature,\ntethered chain areal density ($\\Sigma$), tethered chain length ($N_{t}$), chain\nbending energy ($k_{\\theta}$) and tensile pull velocity ($v$) on the adhesive\nfailure mechanisms of pullout and/or scission of the tethered chains. We\nobserve a crossover from pure chain pullout to chain scission as $N_{t}$ is\nincreased. Below the glass transition, the value of $N_{t}$ for which this\ncrossover begins approaches the bulk entanglement length $N_{e}$. For the\nvalues of $N_{t}$ and $\\Sigma$ used here, no crossover to crazing is observed.",
        "category": "cond-mat"
    },
    {
        "text": "Relativity Restored: Dirac Anisotropy in QED$_3$: We show that at long lengthscales and low energies and to leading order in\n1/N expansion, the anisotropic QED in 2+1 dimensions renormalizes to an\nisotropic limit. Consequently, the (Euclidean) relativistic invariance of the\ntheory is spontaneously restored at the isotropic critical point, characterized\nby the anomalous dimension exponent of the Dirac fermion propagator $\\eta$. We\nfind $\\eta=16/3\\pi^2 N$.",
        "category": "cond-mat"
    },
    {
        "text": "A van der Waals pn heterojunction with organic/inorganic semiconductors: van der Waals (vdW) heterojunctions formed by two-dimensional (2D) materials\nhave attracted tremendous attention due to their excellent electrical/optical\nproperties and device applications. However, current 2D heterojunctions are\nlargely limited to atomic crystals, and hybrid organic/inorganic structures are\nrarely explored. Here, we fabricate hybrid 2D heterostructures with p-type\ndioctylbenzothienobenzothiophene (C8-BTBT) and n-type MoS2. We find that\nfew-layer C8-BTBT molecular crystals can be grown on monolayer MoS2 by vdW\nepitaxy, with pristine interface and controllable thickness down to monolayer.\nThe operation of the C8-BTBT/MoS2 vertical heterojunction devices is highly\ntunable by bias and gate voltages between three different regimes: interfacial\nrecombination, tunneling and blocking. The pn junction shows diode-like\nbehavior with rectifying ratio up to 105 at the room temperature. Our devices\nalso exhibit photovoltaic responses with power conversion efficiency of 0.31%\nand photoresponsivity of 22mA/W. With wide material combinations, such hybrid\n2D structures will offer possibilities for opto-electronic devices that are not\npossible from individual constituents.",
        "category": "cond-mat"
    },
    {
        "text": "Analogue of Hamilton-Jacobi theory for the time-evolution operator: In this paper we develop an analogue of Hamilton-Jacobi theory for the\ntime-evolution operator of a quantum many-particle system. The theory offers a\nuseful approach to develop approximations to the time-evolution operator, and\nalso provides a unified framework and starting point for many well-known\napproximations to the time-evolution operator. In the important special case of\nperiodically driven systems at stroboscopic times, we find relatively simple\nequations for the coupling constants of the Floquet Hamiltonian, where a\nstraightforward truncation of the couplings leads to a powerful class of\napproximations. Using our theory, we construct a flow chart that illustrates\nthe connection between various common approximations, which also highlights\nsome missing connections and associated approximation schemes. These missing\nconnections turn out to imply an analytically accessible approximation that is\nthe \"inverse\" of a rotating frame approximation and thus has a range of\nvalidity complementary to it. We numerically test the various methods on the\none-dimensional Ising model to confirm the ranges of validity that one would\nexpect from the approximations used. The theory provides a map of the relations\nbetween the growing number of approximations for the time-evolution operator.\nWe describe these relations in a table showing the limitations and advantages\nof many common approximations, as well as the new approximations introduced in\nthis paper.",
        "category": "cond-mat"
    },
    {
        "text": "Ultra cold atoms and Bose-Einstein condensation for quantum metrology: This paper is a short introduction to cold atom physics and Bose-Einstein\ncondensation. Light forces on atoms are presented, together with laser cooling,\nand a few atom traps: the magneto-optical trap, dipole traps and magnetic\ntraps. A brief description of Bose-Einstein condensation is given together with\nsome important links with condensed matter physics. The reader is referred to\ncomprehensive reviews and to other lecture notes for further details on atom\ncooling, trapping and Bose-Einstein condensation.",
        "category": "cond-mat"
    },
    {
        "text": "Anisotropic signatures of the electronic correlations in the electrical\n  resistivity of UTe$_2$: Multiple unconventional superconducting phases are suspected to be driven by\nmagnetic fluctuations in the heavy-fermion paramagnet UTe$_2$, and a challenge\nis to identify the signatures of the electronic correlations, including the\nmagnetic fluctuations, in the bulk physical quantities. Here, we investigate\nthoroughly the anisotropy of the electrical resistivity of UTe$_2$ under\nintense magnetic fields up to 70~T, for different electrical-current and\nmagnetic-field configurations. Two characteristic temperatures and an\nanisotropic low-temperature Fermi-liquid-like coefficient $A$, controlled by\nthe electronic correlations, are extracted. Their critical behavior near the\nmetamagnetic transition induced at $\\mu_0H_m\\simeq35$~T for\n$\\mathbf{H}\\parallel\\mathbf{b}$ is characterized. Anisotropic scattering\nprocesses are evidenced and magnetic fluctuations are proposed to contribute,\nvia a Kondo hybridization, to the electrical resistivity. Our work appeals for\na microscopic modeling of the anisotropic contributions to the electrical\nresistivity as a milestone for understanding magnetically-mediated\nsuperconductivity in UTe$_2$.",
        "category": "cond-mat"
    },
    {
        "text": "Ground State Properties of Anti-Ferromagnetic Spinor Bose gases in One\n  Dimension: We investigate the ground state properties of anti-ferromagnetic spin-1 Bose\ngases in one dimensional harmonic potential from the weak repulsion regime to\nthe strong repulsion regime. By diagonalizing the Hamiltonian in the Hilbert\nspace composed of the lowest eigenstates of single particle and spin\ncomponents, the ground state wavefunction and therefore the density\ndistributions, magnetization distribution, one body density matrix, and\nmomentum distribution for each components are obtained. It is shown that the\nspinor Bose gases of different magnetization exhibit the same total density\nprofiles in the full interaction regime, which evolve from the single peak\nstructure embodying the properties of Bose gases to the fermionized shell\nstructure of spin-polarized fermions. But each components display different\ndensity profiles, and magnetic domains emerge in the strong interaction limit\nfor $M=0.25$. In the strong interaction limit, one body density matrix and the\nmomentum distributions exhibit the same behaviours as those of spin-polarized\nfermions. The fermionization of momentum distribution takes place, in contrast\nto the $\\delta$-function-like distribution of single component Bose gases in\nthe full interaction region.",
        "category": "cond-mat"
    },
    {
        "text": "Spinodal decomposition stabilizes plastic flow in a nanocrystalline\n  Cu-Ti alloy: A combination of high strength and reasonable ductility has been achieved in\na copper-1.7 at.%titanium alloy deformed by high-pressure torsion. Grain\nrefinement and a spinodal microstructure provided a hardness of 254 +/- 2 HV ,\nyield strength of 800 MPa and elongation of 10%. The spinodal structure\npersisted during isothermal ageing, further increasing the yield strength to\n890MPa while retaining an elongation of 7%. This work demonstrates the\npotential for spinodal microstructures to overcome the difficulties in\nretaining ductility in ultra-fine grained or nanocrystalline alloys, especially\nupon post-deformation heating where strain softening normally results in\nbrittle behavior.",
        "category": "cond-mat"
    },
    {
        "text": "Ultrafast Calculation of Diffuse Scattering from Atomistic Models: Diffuse scattering is a rich source of information about disorder in\ncrystalline materials, which can be modelled using atomistic techniques such as\nMonte Carlo and molecular dynamics simulations. Modern X-ray and neutron\nscattering instruments can rapidly measure large volumes of diffuse-scattering\ndata. Unfortunately, current algorithms for atomistic diffuse-scattering\ncalculations are too slow to model large data sets completely, because the fast\nFourier transform (FFT) algorithm has long been considered unsuitable for such\ncalculations [Butler & Welberry, J. Appl. Cryst. 25, 391 (1992)]. Here, a new\napproach is presented for ultrafast calculation of atomistic diffuse-scattering\npatterns. It is shown that the FFT can actually be used to perform such\ncalculations rapidly, and that a fast method based on sampling theory can be\nused to reduce high-frequency noise in the calculations. These algorithms are\nbenchmarked using realistic examples of compositional, magnetic and displacive\ndisorder. They accelerate the calculations by a factor of at least 100, making\nrefinement of atomistic models to large diffuse-scattering volumes practical.",
        "category": "cond-mat"
    },
    {
        "text": "Bound on Eigenstate Thermalization from Transport: We show that macroscopic thermalization and transport impose constraints on\nmatrix elements entering the Eigenstate Thermalization Hypothesis (ETH) ansatz\nand require them to be correlated. It is often assumed that the ETH reduces to\nRandom Matrix Theory (RMT) below the Thouless energy scale. We show this\nconventional picture is not self-consistent. We prove that energy scale at\nwhich the RMT behavior emerges has to be parametrically smaller than the\ninverse timescale of the slowest thermalization mode coupled to the operator of\ninterest. We argue that the timescale marking the onset of the RMT behavior is\nthe same timescale at which hydrodynamic description of transport breaks down.",
        "category": "cond-mat"
    },
    {
        "text": "Disorder and non-Hermiticity in Kitaev spin liquids with a Majorana\n  Fermi surface: We study the effect of disorder on Z$_2$ quantum spin liquids with a Majorana\nFermi line (respectively surface in three dimensions) and show that depending\non the symmetries that are preserved \\emph{on average} qualitatively different\nscenarios will occur.\n  In particular, we identify the relevant non-Hermitian symmetries for which\ndisorder will effectively split the Fermi line into two exceptional lines, with\n$\\Re(E)=0$ states filling the area in between. We demonstrate the different\nscenarios using both toy models as well as large-scale numerical simulations.",
        "category": "cond-mat"
    },
    {
        "text": "The metastate approach to thermodynamic chaos: In realistic disordered systems, such as the Edwards-Anderson (EA) spin\nglass, no order parameter, such as the Parisi overlap distribution, can be both\ntranslation-invariant and non-self-averaging. The standard mean-field picture\nof the EA spin glass phase can therefore not be valid in any dimension and at\nany temperature. Further analysis shows that, in general, when systems have\nmany competing (pure) thermodynamic states, a single state which is a mixture\nof many of them (as in the standard mean-field picture) contains insufficient\ninformation to reveal the full thermodynamic structure. We propose a different\napproach, in which an appropriate thermodynamic description of such a system is\ninstead based on a metastate, which is an ensemble of (possibly mixed)\nthermodynamic states. This approach, modelled on chaotic dynamical systems, is\nneeded when chaotic size dependence (of finite volume correlations) is present.\nHere replicas arise in a natural way, when a metastate is specified by its\n(meta)correlations. The metastate approach explains, connects, and unifies such\nconcepts as replica symmetry breaking, chaotic size dependence and replica\nnon-independence. Furthermore, it replaces the older idea of non-self-averaging\nas dependence on the bulk couplings with the concept of dependence on the state\nwithin the metastate at fixed coupling realization. We use these ideas to\nclassify possible metastates for the EA model, and discuss two scenarios\nintroduced by us earlier --- a nonstandard mean-field picture and a picture\nintermediate between that and the usual scaling/droplet picture.",
        "category": "cond-mat"
    },
    {
        "text": "Equivalence of wave function matching and Green's functions methods for\n  quantum transport: generalized Fisher-Lee relation: We present a proof of an exact equivalence of the two approaches that are\nmost used in computing conductance in quantum electron and phonon transport:\nthe wave function matching and Green's functions methods. We can obtain all the\nquantities defined in one method starting from those obtained in the other.\nThis completes and illuminates the work started Ando[Ando T 1991 Phys. Rev. B\n44 8017] and continued later by Komyakov et al.[Khomyakov P A, Brocks G, Karpan\nV, Zwierzycki M and Kelly P J 2005 Phys. Rev. B 72 035450]. The aim is to allow\nfor solving the transport problem with whichever approach fits most the system\nat hand. One major corollary of the proven equivalence is our derivation of a\ngeneralized Fisher-Lee formula for resolving the transmission function into\nindividual phonon mode contributions. As an illustration, we applied our method\nto a simple model to highlight its accuracy and simplicity.",
        "category": "cond-mat"
    },
    {
        "text": "Spontaneous multipole ordering by local parity mixing: Broken spatial inversion symmetry in spin-orbital coupled systems leads to a\nmixing between orbitals with different parity, which results in unusual\nelectronic structures and transport properties. We theoretically investigate\nthe possibility of multipole ordering induced by a parity mixing. In\nparticular, we focus on the system in which the parity mixing appears in a\nsublattice-dependent form. Starting from the periodic Anderson model with such\na local parity mixing, we derive an extended Kondo lattice model with\nsublattice-dependent antisymmetric exchange couplings between itinerant\nelectrons and localized spins. By the variational calculation, simulated\nannealing, and Monte Carlo simulation, we show that the model on a\nquasi-one-dimensional zig-zag lattice exhibits an odd-parity multipole order\ncomposed of magnetic toroidal and quadrupole components at and near half\nfilling. The multipole order causes a band deformation with the band bottom\nshift and a magnetoelectric response. The results suggest that unusual\nodd-parity multipole orders will be widely observed in multi-orbital systems\nwith local parity mixing.",
        "category": "cond-mat"
    },
    {
        "text": "Cold spots in quantum systems far from equilibrium: local entropies and\n  temperatures near absolute zero: We consider a question motivated by the third law of thermodynamics: can\nthere be a local temperature arbitrarily close to absolute zero in a\nnonequilibrium quantum system? We consider nanoscale quantum conductors with\nthe source reservoir held at finite temperature and the drain held at or near\nabsolute zero, a problem outside the scope of linear response theory. We obtain\nlocal temperatures close to absolute zero when electrons originating from the\nfinite temperature reservoir undergo destructive quantum interference. The\nlocal temperature is computed by numerically solving a nonlinear system of\nequations describing equilibration of a scanning thermoelectric probe with the\nsystem, and we obtain excellent agreement with analytic results derived using\nthe Sommerfeld expansion. A local entropy for a nonequilibrium quantum system\nis introduced, and used as a metric quantifying the departure from local\nequilibrium. It is shown that the local entropy of the system tends to zero\nwhen the probe temperature tends to zero, consistent with the third law of\nthermodynamics.",
        "category": "cond-mat"
    },
    {
        "text": "Deconstructing Magnetization Noise: Degeneracies, Phases, and Mobile\n  Fractionalized Excitations in Tetris Artificial Spin Ice: Direct detection of spontaneous spin fluctuations, or \"magnetization noise\",\nis emerging as a powerful means of revealing and studying magnetic excitations\nin both natural and artificial frustrated magnets. Depending on the lattice and\nnature of the frustration, these excitations can often be described as\nfractionalized quasiparticles possessing an effective magnetic charge. Here, by\ncombining ultrasensitive optical detection of thermodynamic magnetization noise\nwith Monte Carlo simulations, we reveal emergent regimes of magnetic\nexcitations in artificial \"tetris ice\". A marked increase of the intrinsic\nnoise at certain applied magnetic fields heralds the spontaneous proliferation\nof fractionalized excitations, which can diffuse independently, without cost in\nenergy, along specific quasi-1D spin chains in the tetris ice lattice.",
        "category": "cond-mat"
    },
    {
        "text": "Winding up superfluid in a torus via Bose Einstein condensation: We simulate Bose-Einstein condensation (BEC) in a ring employing stochastic\nGross-Pitaevskii equation and show that cooling through the critical\ntemperature can generate spontaneous quantized circulation around the ring of\nthe newborn condensate. Dispersion of the resulting winding numbers follows\nscaling law predicted by the Kibble-Zurek mechanism (KZM). Density growth also\nexhibits scaling behavior consistent with KZM. This paves a way towards\nexperimental verification of KZM scalings, and experimental determination of\ncritical exponents for the BEC transition.",
        "category": "cond-mat"
    },
    {
        "text": "Time-dependent matrix product ansatz for interacting reversible dynamics: We present an explicit time-dependent matrix product ansatz (tMPA) which\ndescribes the time-evolution of any local observable in an interacting and\ndeterministic lattice gas, specifically for the rule 54 reversible cellular\nautomaton of [Bobenko et al., Commun. Math. Phys. 158, 127 (1993)]. Our\nconstruction is based on an explicit solution of real-space real-time inverse\nscattering problem. We consider two applications of this tMPA. Firstly, we\nprovide the first exact and explicit computation of the dynamic structure\nfactor in an interacting deterministic model, and secondly, we solve the\nextremal case of the inhomogeneous quench problem, where a semi-infinite\nlattice in the maximum entropy state is joined with an empty semi-infinite\nlattice. Both of these exact results rigorously demonstrate a coexistence of\nballistic and diffusive transport behaviour in the model, as expected for\nnormal fluids.",
        "category": "cond-mat"
    },
    {
        "text": "Curved non-interacting two-dimensional electron gas with anisotropic\n  mass: In the da Costa's thin-layer approach, a quantum particle moving in a 3D\nsample is confined on a curved thin interface. At the end, the interface\neffects are ignored and such quantum particle is localized on a curved surface.\nA geometric potential arises and, since it manifests due to this confinement\nprocedure, it depends on the transverse to the surface mass component. This\ninspired us to consider, in this paper, the effects due to an anisotropic\neffective mass on a non-interacting two dimensional electron gas confined on a\ncurved surface, a fact not explored before in this context. By tailoring the\nmass, many investigations carried out in the literature can be improved which\nin turns can be useful to better designing electronic systems without modifying\nthe geometry of a given system. Some examples are examined here, as a particle\non helicoidal surface, on a cylinder, on a catenoid and on a cone, with some\npossible applications briefly discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Elastohydrodynamics of swimming helices: effects of flexibility and\n  confinement: Motivated by bacterial transport through porous media, here we study the\nswimming of an actuated, flexible helical filament in both three-dimensional\nfree space and within a cylindrical tube whose diameter is much smaller than\nthe length of the helix. The filament, at rest, has a native helical shape\nmodeled after the geometry of a typical bacterial flagellar bundle. The finite\nlength filament is a free swimmer, and is driven by an applied torque as well\nas a counter-torque (of equal strength and opposite direction) that represents\na virtual cell body. We use a regularized Stokeslet framework to examine the\nshape changes of the flexible filament in response to the actuation as well as\nthe swimming performance as a function of the nondimensional Sperm number that\ncharacterizes the elastohydrodynamic system. We also show that a modified Sperm\nnumber may be defined to characterize the swimming progression within a tube.\nFinally, we demonstrate that a helical filament whose axis is not aligned with\nthe tube axis can exhibit centering behavior in the narrowest tubes.",
        "category": "cond-mat"
    },
    {
        "text": "Novel Laves phase superconductor NbBe2: A theoretical investigation: A new Laves phase superconductor NbBe2, prototype with MgCu2, having maximum\nTc ~2.6 K has been reported very recently. Based on first-principle\ncalculations, we systematically study the structural, elastic, mechanical,\nelectronic, thermal and superconducting properties of the newly reported\nsuperconducting intermetallic compound NbBe2. Finally, we investigate the\nelectron-phonon coupling constant, phonon dispersion curve and density of\nstates which indicates that the compound under study is a weakly coupled BCS\nsuperconductor.",
        "category": "cond-mat"
    },
    {
        "text": "Third-order optical conductivity of an electron fluid: We derive the nonlinear optical conductivity of an isotropic electron fluid\nat frequencies below the interparticle collision rate. In this regime, governed\nby hydrodynamics, the conductivity acquires a universal form at any\ntemperature, chemical potential, and spatial dimension. We show that the\nnonlinear response of the fluid to a uniform field is dominated by the\nthird-order conductivity tensor $\\sigma^{(3)}$ whose magnitude and temperature\ndependence differ qualitatively from those in the conventional kinetic regime\nof higher frequencies. We obtain explicit formulas for $\\sigma^{(3)}$ for Dirac\nmaterials such as graphene and Weyl semimetals. We make predictions for the\nthird-harmonic generation, renormalization of the collective-mode spectrum, and\nthe third-order circular magnetic birefringence experiments.",
        "category": "cond-mat"
    },
    {
        "text": "Asymptotic Freedom and Large Spin Antiferromagnetic Chains: Building on the mapping of large-$S$ spin chains onto the O($3$) nonlinear\n$\\sigma$ model with coupling constant $2/S$, and on general properties of that\nmodel (asymptotic freedom, implying that perturbation theory is valid at high\nenergy, and Elitzur's conjecture that rotationally invariant quantities are\ninfrared finite in perturbation theory), we use the Holstein-Primakoff\nrepresentation to derive analytic expressions for the equal-time and dynamical\nspin-spin correlations valid at distances smaller than $S^{-1} \\exp(\\pi S)$ or\nat energies larger than $J S^2 \\exp(-\\pi S)$, where $J$ is the Heisenberg\nexchange coupling. This is supported by comparing the static correlations with\nquantum Monte Carlo simulations for $S = 5/2$.",
        "category": "cond-mat"
    },
    {
        "text": "Heat capacity of Schottky type in low-dimensional spin system: The heat capacity of low-dimensional spin systems is studied using\ntheoretical and numerical techniques. Keeping only two energy states, the\nsystem is mapped onto the two -level-system (TLS) model. Using the low\ntemperature Lanczos method, it is confirmed that the behavior of $T_{M}$ and\nthe energy gap as functions of the control parameter is the same in the two\nmodels studied; a conclusion that can probably be extrapolated to the general\ncase of any system that possesses an energy gap.",
        "category": "cond-mat"
    },
    {
        "text": "Correlation and confinement induced itinerant ferromagnetism in chain\n  structures: Using a positive semidefinite operator technique one deduces exact ground\nstates for a zig-zag hexagon chain described by a non-integrable Hubbard model\nwith on-site repulsion. Flat bands are not present in the bare band structure,\nand the operators $\\hat B^{\\dagger}_{\\mu,\\sigma}$ introducing the electrons\ninto the ground state, are all extended operators and confined in the quasi 1D\nchain structure of the system. Consequently, increasing the number of carriers,\nthe $\\hat B^{\\dagger}_{\\mu,\\sigma}$ operators become connected i.e. touch each\nother on several lattice sites. Hence the spin projection of the carriers\nbecomes correlated in order to minimize the ground state energy by reducing as\nmuch as possible the double occupancy leading to a ferromagnetic ground state.\nThis result demonstrates in exact terms in a many-body frame that the\nconjecture made at two-particle level by G. Brocks et al.\n[Phys.Rev.Lett.93,146405,(2004)] that the Coulomb interaction is expected to\nstabilize correlated magnetic ground states in acenes is clearly viable, and\nopens new directions in the search for routes in obtaining organic\nferromagnetism. Due to the itinerant nature of the obtained ferromagnetic\nground state, the systems under discussion may have also direct application\npossibilities in spintronics.",
        "category": "cond-mat"
    },
    {
        "text": "Resistive state of superconducting structures with fractal clusters of a\n  normal phase: The effect of morphologic factors on magnetic flux dynamics and critical\ncurrents in percolative superconducting structures is considered. The\nsuperconductor contains the fractal clusters of a normal phase, which act as\npinning centers. The properties of these clusters are analyzed in the general\ncase of gamma-distribution of their areas. The statistical characteristics of\nthe normal phase clusters are studied, the critical current distribution is\nderived, and the dependencies of the main statistical parameters on the fractal\ndimension are found. The effect of fractal clusters of a normal phase on the\nelectric field induced by the motion of the magnetic flux after the vortices\nhave been broken away from pinning centers is considered. The voltage-current\ncharacteristics of fractal superconducting structures in a resistive state for\nan arbitrary fractal dimension are obtained. It is found that the fractality of\nthe boundaries of normal phase clusters intensifies magnetic flux trapping and\nthereby increases the current-carrying capability of the superconductor.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetotransport near a quantum critical point in a simple metal: We use geometric considerations to study transport properties, such as the\nconductivity and Hall coefficient, near the onset of a nesting-driven spin\ndensity wave in a simple metal. In particular, motivated by recent experiments\non vanadium-doped chromium, we study the variation of transport coefficients\nwith the onset of magnetism within a mean-field treatment of a model that\ncontains nearly nested electron and hole Fermi surfaces. We show that most\ntransport coefficients display a leading dependence that is linear in the\nenergy gap. The coefficient of the linear term, though, can be small. In\nparticular, we find that the Hall conductivity $\\sigma_{xy}$ is essentially\nunchanged, due to electron-hole compensation, as the system goes through the\nquantum critical point. This conclusion extends a similar observation we made\nearlier for the case of completely flat Fermi surfaces to the immediate\nvicinity of the quantum critical point where nesting is present but not\nperfect.",
        "category": "cond-mat"
    },
    {
        "text": "Flagellated bacterial motility in polymer solutions: It is widely believed that the swimming speed, $v$, of many flagellated\nbacteria is a non-monotonic function of the concentration, $c$, of\nhigh-molecular-weight linear polymers in aqueous solution, showing peaked\n$v(c)$ curves. Pores in the polymer solution were suggested as the explanation.\nQuantifying this picture led to a theory that predicted peaked $v(c)$ curves.\nUsing new, high-throughput methods for characterising motility, we have\nmeasured $v$, and the angular frequency of cell-body rotation, $\\Omega$, of\nmotile Escherichia coli as a function of polymer concentration in\npolyvinylpyrrolidone (PVP) and Ficoll solutions of different molecular weights.\nWe find that non-monotonic $v(c)$ curves are typically due to low-molecular\nweight impurities. After purification by dialysis, the measured $v(c)$ and\n$\\Omega(c)$ relations for all but the highest molecular weight PVP can be\ndescribed in detail by Newtonian hydrodynamics. There is clear evidence for\nnon-Newtonian effects in the highest molecular weight PVP solution.\nCalculations suggest that this is due to the fast-rotating flagella `seeing' a\nlower viscosity than the cell body, so that flagella can be seen as\nnano-rheometers for probing the non-Newtonian behavior of high polymer\nsolutions on a molecular scale.",
        "category": "cond-mat"
    },
    {
        "text": "Emergence of multi-body interactions in few-atom sites of a fermionic\n  lattice clock: Alkaline-earth (AE) atoms have metastable clock states with minute-long\noptical lifetimes, high-spin nuclei, and SU($N$)-symmetric interactions that\nuniquely position them for advancing atomic clocks, quantum information\nprocessing, and quantum simulation. The interplay of precision measurement and\nquantum many-body physics is beginning to foster an exciting scientific\nfrontier with many opportunities. Few particle systems provide a window to view\nthe emergence of complex many-body phenomena arising from pairwise\ninteractions. Here, we create arrays of isolated few-body systems in a\nfermionic ${}^{87}$Sr three-dimensional (3D) optical lattice clock and use high\nresolution clock spectroscopy to directly observe the onset of both elastic and\ninelastic multi-body interactions. These interactions cannot be broken down\ninto sums over the underlying pairwise interactions. We measure\nparticle-number-dependent frequency shifts of the clock transition for atom\nnumbers $n$ ranging from 1 to 5, and observe nonlinear interaction shifts,\nwhich are characteristic of SU($N$)-symmetric elastic multi-body effects. To\nstudy inelastic multi-body effects, we use these frequency shifts to isolate\n$n$-occupied sites and measure the corresponding lifetimes. This allows us to\naccess the short-range few-body physics free from systematic effects\nencountered in a bulk gas. These measurements, combined with theory, elucidate\nan emergence of multi-body effects in few-body systems of sites populated with\nground-state atoms and those with single electronic excitations. By connecting\nthese few-body systems through tunneling, the favorable energy and timescales\nof the interactions will allow our system to be utilized for studies of\nhigh-spin quantum magnetism and the Kondo effect.",
        "category": "cond-mat"
    },
    {
        "text": "Phase Transitions Driven by Vortices in 2D Superfluids and\n  Superconductors: From Kosterlitz-Thouless to 1st Order: The Landau-Ginzburg-Wilson hamiltonian is studied for different values of the\nparameter $\\lambda$ which multiplies the quartic term (it turns out that this\nis equivalent to consider different values of the coherence length $\\xi$ in\nunits of the lattice spacing $a$). It is observed that amplitude fluctuations\ncan change dramatically the nature of the phase transition: for small values of\n$\\lambda$ ($\\xi/a > 0.7$), instead of the smooth Kosterlitz-Thouless transition\nthere is a {\\em first order} transition with a discontinuous jump in the vortex\ndensity $v$ and a larger non-universal drop in the helicity modulus. In\nparticular, for $\\lambda$ sufficiently small ($\\xi/a \\cong 1$), the density of\nbound pairs of vortex-antivortex below $T_c$ is so low that, $v$ drops to zero\nalmost for all temperature $T<Tc$.",
        "category": "cond-mat"
    },
    {
        "text": "Condensate Fraction and Pair Coherence Lengths of Two-Dimension Fermi\n  Gases with Spin-Orbit Coupling: The effects of Rashba spin-orbit coupling on BCS-BEC crossover, the\ncondensate fraction and pair coherence lengths for a two-component attractive\nFermi gas in two dimension are studied. The results at $T=0K$ indicate that (1)\nwhen the strength of SOC is beyond a critical value, BCS-BEC crossover does not\nhappen in a conventional sense; (2) SOC enhances the condensate fraction, but\nsuppresses pair coherence lengths.",
        "category": "cond-mat"
    },
    {
        "text": "Generation of electric current and electromotive force by an\n  antiferromagnetic domain wall: Dynamic magnetic textures may transfer the angular moment from the varying in\ntime antiferromagnetic order to spins of conduction electrons. Due to the spin\norbit coupling (SOC) these spin excitations can induce the electric current of\nconduction electrons. We calculated the electric current and the electromotive\nforce (EMF) which are produced by a domain wall (DW) moving parallel to the\nmagnetically compensated interface between an antiferromagnetic insulator\n(AFMI) and a two-dimensional spin orbit coupled metal. Spins of conduction\nelectrons interact with localized spins of a collinear AFMI through the\ninterface exchange interaction. The Keldysh formalism of nonequilibrium Green\nfunctions was applied for the analysis of this system. It is shown that a Bloch\nDW generates the current perpendicular to the DW motion direction. At the same\ntime a N\\'{e}el DW creates the electric potential which builds up across the\nwall. The total charge which is pumped by a Bloch DW can be expressed in terms\nof a topologically invariant charge quantum. The latter does not depend on\nvariations of DW's velocity and shape. These effects increase dramatically when\nthe Fermi energy approaches the van Hove singularity of the Fermi surface. The\nobtained results are important for the electrical detection and control of\ndynamic magnetic textures in antiferromagnets.",
        "category": "cond-mat"
    },
    {
        "text": "Hausdorff dimension and filling factor: We propose a new hierarchy scheme for the filling factor, a parameter which\ncharacterizes the occurrence of the Fractional Quantum Hall Effect (FQHE). We\nconsider the Hausdorff dimension, $h$, as a parameter for classifying\nfractional spin particles, such that, it is written in terms of the statistics\nof the collective excitations. The number $h$ classifies these excitations with\ndifferent statistics in terms of its homotopy class.",
        "category": "cond-mat"
    },
    {
        "text": "Bounding the coarse graining error in hidden Markov dynamics: Lumping a Markov process introduces a coarser level of description that is\nuseful in many contexts and applications. The dynamics on the coarse grained\nstates is often approximated by its Markovian component. In this letter we\nderive finite-time bounds on the error in this approximation. These results\nhold for non-reversible dynamics and for probabilistic mappings between\nmicroscopic and coarse grained states.",
        "category": "cond-mat"
    },
    {
        "text": "Drude weight in systems with open boundary conditions: For finite systems, the real part of the conductivity is usually decomposed\nas the sum of a zero frequency delta peak and a finite frequency regular part.\nIn studies with periodic boundary conditions, the Drude weight, i.e., the\nweight of the zero frequency delta peak, is found to be nonzero for integrable\nsystems, even at very high temperatures, whereas it vanishes for generic\n(nonintegrable) systems. Paradoxically, for systems with open boundary\nconditions, it can be shown that the coefficient of the zero frequency delta\npeak is identically zero for any finite system, regardless of its\nintegrability. In order for the Drude weight to be a thermodynamically\nmeaningful quantity, both kinds of boundary conditions should produce the same\nanswer in the thermodynamic limit. We shed light on these issues by using\nanalytical and numerical methods.",
        "category": "cond-mat"
    },
    {
        "text": "Giant current-driven domain wall mobility in (Ga,Mn)As: We study theoretically hole current-driven domain wall dynamics in (Ga,Mn)As.\nWe show that the spin-orbit coupling causes significant hole reflection at the\ndomain wall, even in the adiabatic limit when the wall is much thicker than the\nFermi wavelength, resulting in spin accumulation and mistracking between\ncurrent-carrying spins and the domain wall magnetization. This increases the\nout-of-plane non-adiabatic spin transfer torque and consequently the\ncurrent-driven domain wall mobility by three to four orders of magnitude.\nTrends and magnitude of the calculated domain wall current mobilities agree\nwith experimental findings.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of orbital relaxation on the band structure of cuprate\n  superconductors and implications for the superconductivity mechanism: Where the doped holes reside in cuprate superconductors has crucial\nimplications for the understanding of the mechanism responsible for their high\ntemperature superconductivity. It has been generally assumed that doped holes\nreside in hybridized Cu $d_{x^2-y^2}$ - O $p\\sigma$ orbitals in the $CuO_2$\nplanes, based on results of density functional band structure calculations.\nInstead, we propose that doped holes in the cuprates reside in O $p\\pi$\norbitals in the plane, perpendicular to the $Cu-O$ bond, that are raised to the\nFermi energy through local orbital relaxation, that is not taken into account\nin band structure calculations that place the bands associated with these\norbitals well below the Fermi energy. We use a dynamic Hubbard model to\nincorporate the orbital relaxation degree of freedom and find in exact\ndiagonalization of a small $Cu_4O_4$ cluster that holes will go to the O $p\\pi$\norbitals for relaxation energies comparable to what is expected from atomic\nproperties of oxygen anions. The bandwidth of this band becomes significantly\nsmaller than predicted by band structure calculations due to the orbital\nrelaxation effect. Within the theory of hole superconductivity the heavy hole\ncarriers in this almost full band will pair and drive the system\nsuperconducting through lowering of their quantum kinetic energy.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum fluctuations of the ultracold atom-molecule mixtures: We investigate evolution of the quantum coherence in the ultracold mixture of\nfermionic atoms and bosonic dimer molecules. Interactions are there\nexperimentally controlled via tuning the external magnetic field. Consequently,\nthe fermionic atoms and their bosonic counterparts can be driven to a behavior\nresembling the usual BCS to BEC crossover. We analyze in some detail how this\nquantum coherence evolves with respect to time upon a smooth and abrupt sweep\nacross the Feshbach resonance inducing the atom-molecule quantum fluctuations.",
        "category": "cond-mat"
    },
    {
        "text": "Phase boundary near a magnetic percolation transition: Motivated by recent experimental observations [Phys. Rev. 96, 020407 (2017)]\non hexagonal ferrites, we revisit the phase diagrams of diluted magnets close\nto the lattice percolation threshold. We perform large-scale Monte Carlo\nsimulations of XY and Heisenberg models on both simple cubic lattices and\nlattices representing the crystal structure of the hexagonal ferrites. Close to\nthe percolation threshold $p_c$, we find that the magnetic ordering temperature\n$T_c$ depends on the dilution $p$ via the power law $T_c \\sim |p-p_c|^\\phi$\nwith exponent $\\phi=1.09$, in agreement with classical percolation theory.\nHowever, this asymptotic critical region is very narrow, $|p-p_c| \\lesssim\n0.04$. Outside of it, the shape of the phase boundary is well described, over a\nwide range of dilutions, by a nonuniversal power law with an exponent somewhat\nbelow unity. Nonetheless, the percolation scenario does not reproduce the\nexperimentally observed relation $T_c \\sim (x_c -x)^{2/3}$ in\nPbFe$_{12-x}$Ga$_x$O$_{19}$. We discuss the generality of our findings as well\nas implications for the physics of diluted hexagonal ferrites.",
        "category": "cond-mat"
    },
    {
        "text": "Charge and spin ordering in Nd{1/3}Sr{2/3}FeO{3}: We have investigated the charge and spin ordering in Nd{1/3}Sr{2/3}FeO{3}\nwith neutron diffraction technique. This sample undergoes a charge ordering\ntransition accompanying charge disproportionation of 2Fe4+ -> Fe3+ + Fe5+. We\nmeasured the superlattice reflections due to the charge and spin ordering, and\nconfirmed that charges and spins order simultaneously at Tco = 185 K. The\nordering pattern of charges and spins in this sample can be viewed as three\ndimensional stripe order, and is compared with two dimensional stripe order\nobserved in other transition metal oxides.",
        "category": "cond-mat"
    },
    {
        "text": "Large deviations for the Pearson family of ergodic diffusion processes\n  involving a quadratic diffusion coefficient and a linear force: The Pearson family of ergodic diffusions with a quadratic diffusion\ncoefficient and a linear force are characterized by explicit dynamics of their\ninteger moments and by explicit relaxation spectral properties towards their\nsteady state. Besides the Ornstein-Uhlenbeck process with a Gaussian steady\nstate, the other representative examples of the Pearson family are the\nSquare-Root or the Cox-Ingersoll-Ross process converging towards the\nGamma-distribution, the Jacobi process converging towards the\nBeta-distribution, the reciprocal-Gamma process (corresponding to an\nexponential functional of the Brownian motion) that converges towards the\nInverse-Gamma-distribution, the Fisher-Snedecor process, and the Student\nprocess, so that the last three steady states display heavy-tails. The goal of\nthe present paper is to analyze the large deviations properties of these\nvarious diffusion processes in a unified framework. We first consider the Level\n1 concerning time-averaged observables over a large time-window $T$ : we write\nthe first rescaled cumulants for generic observables and we identify the\nspecific observables whose large deviations can be explicitly computed from the\ndominant eigenvalue of the appropriate deformed-generator. The explicit large\ndeviations at Level 2 concerning the time-averaged density are then used to\nanalyze the statistical inference of model parameters from data on a very long\nstochastic trajectory in order to obtain the explicit rate function for the two\ninferred parameters of the Pearson linear force.",
        "category": "cond-mat"
    },
    {
        "text": "Three-Dimensional Percolation Modeling of Self-Healing Composites: We study the self-healing process of materials with embedded \"glue\"-carrying\ncells, in the regime of the onset of the initial fatigue. Three-dimensional\nnumerical simulations within the percolation-model approach are reported. The\nmain numerical challenge taken up in the present work, has been to extend the\ncalculation of the conductance to three-dimensional lattices. Our results\nconfirm the general features of the process: The onset of the material fatigue\nis delayed, by developing a plateau-like time-dependence of the material\nquality. We demonstrate that in this low-damage regime, the changes in the\nconductance and thus, in similar transport/response properties of the material\ncan be used as measures of the material quality degradation. A new feature\nfound for three dimensions, where it is much more profound than in\nearlier-studied two-dimensional systems, is the competition between the healing\ncells. Even for low initial densities of the healing cells, they interfere with\neach other and reduce each other's effective healing efficiency.",
        "category": "cond-mat"
    },
    {
        "text": "The Fermi Edge Singularity and Boundary Condition Changing Operators: The boundary conformal field theory approach to quantum impurity problems is\nused to study the Fermi edge singularity, occuring in the X-ray adsorption\nprobablility. The deep-hole creation operator, in the effective low-energy\ntheory, changes the boundary condition on the conduction electrons. By a\nconformal mapping, the dimension of such an operator is related to the\ngroundstate energy for a finite system with different boundary conditions at\nthe two ends. The Fermi edge singularity is solved using this method, for the\nLuttinger liquid including back-scattering and for the multi-channel Kondo\nproblem.",
        "category": "cond-mat"
    },
    {
        "text": "The second law and fluctuations of work: The case against quantum\n  fluctuation theorems: We study how Thomson's formulation of the second law: no work is extracted\nfrom an equilibrium ensemble by a cyclic process, emerges in the quantum\nsituation through the averaging over fluctuations of work. The latter concept\nis carefully defined for an ensemble of quantum systems interacting with\nmacroscopic sources of work. The approach is based on first splitting a mixed\nquantum ensemble into pure subensembles, which according to quantum mechanics\nare maximally complete and irreducible. The splitting is done by filtering the\noutcomes of a measurement process. A critical review is given of two other\napproaches to fluctuations of work proposed in the literature. It is shown that\nin contrast to those ones, the present definition {\\it i)} is consistent with\nthe physical meaning of the concept of work as mechanical energy lost by the\nmacroscopic sources, or, equivalently, as the average energy acquired by the\nensemble; {\\it ii)} applies to an arbitrary non-equilibrium state. There is no\ndirect generalization of the classical work-fluctuation theorem to the proper\nquantum domain. This implies some non-classical scenarios for the emergence of\nthe second law.",
        "category": "cond-mat"
    },
    {
        "text": "Detecting a true quantum pump effect: Even though quantum pumping is a very promising field, it has unfortunately\nnot been unambiguously experimentally detected. The reason being that in the\nexperiments the rectification effect overshadows the pumped current. One of the\nbetter known ways to detect it is by using the magnetic field symmetry\nproperties of the rectified and pumped currents. The rectified currents are\nsymmetric with respect to magnetic field reversal while the pumped currents do\nnot possess any definite symmetry with respect to field reversal. This feature\nhas been exploited in some recent works. In this work we look beyond this\nmagnetic field symmetry properties and provide examples wherein the nature or\nmagnitudes of the pumped and rectified currents are exactly opposite enabling\nan effective distinction between the two.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum back-action evading measurement of collective mechanical modes: The standard quantum limit constrains the precision of an oscillator position\nmeasurement. It arises from a balance between the imprecision and the quantum\nback-action of the measurement. However, a measurement of only a single\nquadrature of the oscillator can evade the back-action and be made with\narbitrary precision. Here we demonstrate quantum back-action evading\nmeasurements of a collective quadrature of two mechanical oscillators, both\ncoupled to a common microwave cavity. The work allows for quantum state\ntomography of two mechanical oscillators, and provides a foundation for\nmacroscopic mechanical entanglement and force sensing beyond conventional\nquantum limits.",
        "category": "cond-mat"
    },
    {
        "text": "Tailoring the flow of soft glasses by soft additives: We examine the vitrification and melting of asymmetric star polymers mixtures\nby combining rheological measurements with mode coupling theory. We identify\ntwo types of glassy states, a {\\it single} glass, in which the small component\nis fluid in the glassy matrix of the big one and a {\\it double} glass, in which\nboth components are vitrified. Addition of small star polymers leads to melting\nof {\\it both} glasses and the melting curve has a non-monotonic dependence on\nthe star-star size ratio. The phenomenon opens new ways for externally steering\nthe rheological behavior of soft matter systems.",
        "category": "cond-mat"
    },
    {
        "text": "Hidden structural transition in epitaxial\n  Ca$_{0.5}$Sr$_{0.5}$IrO$_{3}$/SrTiO$_{3}$ thin film: A structural transition in an ABO$_{3}$ perovskite thin film involving the\nchange of the BO$_{6}$ octahedral rotation pattern can be hidden under the\nglobal lattice symmetry imposed by the substrate and often easily overlooked.\nWe carried out high-resolution x-ray diffraction experiments to investigate the\nstructures of epitaxial Ca$_{0.5}$Sr$_{0.5}$IrO$_{3}$ (CSIO) perovskite iridate\nfilms grown on the SrTiO$_{3}$ (STO) and GdScO$_{3}$ (GSO) substrates in\ndetail. Although the CSIO/STO film layer displays a global tetragonal lattice\nsymmetry evidenced by the reciprocal space mapping, synchrotron x-ray data\nindicates that its room temperature structure is monoclinic due to Glazer's\na$^{+}$a$^{-}$c$^{-}$-type rotation of the IrO$_{6}$ octahedra. In order to\naccommodate the lower-symmetry structure under the global tetragonal symmetry,\nthe film breaks into four twinned domains, resulting in the splitting of the\n(half-integer, 0, integer) superlattice reflections. Surprisingly, the\nsplitting of these superlattice reflections decrease with increasing\ntemperature, eventually disappearing at T$_{S}$ = 510(5) K, which signals a\nstructural transition to an orthorhombic phase with a$^{+}$a$^{-}$c$^{0}$\noctahedral rotation. In contrast, the CSIO/GSO film displays a stable\nmonoclinic symmetry with a$^{+}$b$^{-}$c$^{-}$ octahedral rotation, showing no\nstructural instability caused by the substrate up to 520 K. Our study\nillustrates the importance of the symmetry in addition to the lattice mismatch\nof the substrate in determining the structure of epitaxial thin films.",
        "category": "cond-mat"
    },
    {
        "text": "Effect of one-dimensional superlattice potentials on the band gap of\n  two-dimensional materials: Using the tight-binding approach, we analyze the effect of a one-dimensional\nsuperlattice (1DSL) potential on the electronic structure of black phosphorene\nand transition metal dichalcogenides. We observe that the 1DSL potential\nresults in a decrease of the energy band gap of the two-dimensional (2D)\nmaterials. An analytical model is presented to relate the decrease in the\ndirect-band gap to the different orbital characters between the valence band\ntop and conduction band bottom of the 2D materials. The direct-to-indirect gap\ntransition, which occurs under a 1DSL potential with an unequal barrier width,\nis also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "The Heart of Fidelity: The multi-electron wave function of an interacting electron system depends on\nthe size of the system, i.e. the number of electrons. Here the question\ninvestigated is how the wave function changes for a symmetric Friedel-Anderson\nimpurity when the volume is doubled. It turns out that for sufficiently large\nvolume (when the level spacing is smaller than the resonance width) the change\nin the wave function can be expressed in terms of a universal single-electron\nstate |q> centered at the Fermi level. This electron state is independent of\nthe number of electrons and independent of the parameters of the\nFriedel-Anderson impurity. It is even the same universal state for a Kondo\nimpurity and a symmetric Friedel impurity independent of any parameter. The\nonly requirement is that the impurity has a resonance exactly at the Fermi\nlevel and that the level spacing is smaller than the resonance width. This\nresult clarifies recent fidelity calculations.",
        "category": "cond-mat"
    },
    {
        "text": "Three-body local correlation function in the Lieb-Liniger model:\n  bosonization approach: We develop a method for the calculation of vacuum expectation values of local\noperators in the Lieb-Liniger model. This method is based on a set of new\nidentities obtained using integrability and effective theory (``bosonization'')\ndescription. We use this method to get an explicit expression for the\nthree-body local correlation function, measured in a recent experiment [1].",
        "category": "cond-mat"
    },
    {
        "text": "On the Belitz-Kirkpatrick comment on \"Specific heat of a Fermi system\n  near ferromagnetic quantum phase transition\", by I.Grosu, D.Bodea and\n  M.Crisan (cond-mat/0101392): We reply to Belitz and Kirkpatrick comment cond-mat/0102064, on\ncond-mat/0101392.",
        "category": "cond-mat"
    },
    {
        "text": "Limit of validity of Ostwald's rule of stages in a statistical\n  mechanical model of crystallization: We have only rules of thumb with which to predict how a material will\ncrystallize, chief among which is Ostwald's rule of stages. It states that the\nfirst phase to appear upon transformation of a parent phase is the one closest\nto it in free energy. Although sometimes upheld, the rule is without\ntheoretical foundation and is not universally obeyed, highlighting the need for\nmicroscopic understanding of crystallization controls. Here we study in detail\nthe crystallization pathways of a prototypical model of patchy particles. The\nrange of crystallization pathways it exhibits is richer than can be predicted\nby Ostwald's rule, but a combination of simulation and analytic theory reveals\nclearly how these pathways are selected by microscopic parameters. Our results\nsuggest strategies for controlling self-assembly pathways in simulation and\nexperiment.",
        "category": "cond-mat"
    },
    {
        "text": "d0 Ferromagnetism in Mg-doped Rutile TiO2 Nanoparticles: In a quest of enriching the area of d0 magnetism in oxide materials, we have\nundertaken to study Mg-doped TiO2 compounds. The Ti1-xMgxO2 (x=0, 0.02, 0.04\nand 0.06) nanoparticles were prepared by solid-state reaction route. The X-ray\ndiffractions (XRD) patterns of these samples indicate single phase of\ntetragonal rutile-structure of TiO2. The refinement of the XRD patterns reveals\nno change in the crystallographic lattice parameters in comparison to pure TiO2\nupon Mg doping and it indicates that Mg2+ ions do not enter core grains and\nform core/shell structure. SEM observations reveal the uniform morphology with\nnanometric grains in the range of 150-200 nm. The measurement of magnetic\nproperties of these compounds indicates that pure TiO2 and Ti0.98Mg0.02\ncompounds exhibit paramagnetic behavior and Ti0.96Mg0.04 compound exhibits\nferromagnetic (FM) phase superimposed with the dominating paramagnetic phase.\nHowever, Ti0.94Mg0.06 compound exhibits ferromagnetic to paramagnetic\ntransition with FM transition temperature of 180.2 K. The measurements of zero\nfield and field cooled magnetization data indicate low temperature magnetic\nirreversibility for x=0.06 sample and it was attributed to the competing AFM\n(core) and the FM (shell) interactions. The measurement of hysteresis curves at\nvarious temperatures indicates domain wall pinning and an exchange-bias\nbehavior.",
        "category": "cond-mat"
    },
    {
        "text": "The Sine-Gordon Wobble: Nonperturbative, oscillatory, winding number one solutions of the Sine-Gordon\nequation are presented and studied numerically. We call these nonperturbative\nshape modes {\\sl wobble} solitons. Perturbed Sine-Gordon kinks are found to\ndecay to {\\sl wobble} solitons.",
        "category": "cond-mat"
    },
    {
        "text": "An efficient method to calculate the anharmonicity free energy: The anharmonicity resulted from the intrinsic phonon interaction is neglected\nby quasiharmonic approximation. Although the intensive researches about\nanharmonicity have been done, up to now the free energy contributed by the\nanharmonicity is still difficult to calculate. Here we put forward a new method\nthat can well include the anharmonicity. We introduce the implicit temperature\ndependence of effective frequency by volume modification. The quasiharmonic\napproximation becomes a special case in our method corresponding to non volume\nmodification. Although our method is simple and only a constant need to\ndetermine, the anharmonicity is well included. Thermodynamic properties of MgO\npredicted with our method are excellent consistent with the experiment results\nat very wide temperature range. We also believe that our method will be helpful\nto reveal the characteristic of anharmonicity and intrinsic phonon interaction.",
        "category": "cond-mat"
    },
    {
        "text": "Spectroscopic evidence for a charge-density-wave condensate in a\n  charge-ordered manganite: Observation of collective excitation mode in\n  Pr$_{\\text{0.7}}$Ca$_{\\text{0.3}}$MnO$_{\\text{3}}$ by using THz time-domain\n  spectroscopy: THz time-domain spectroscopy was used to directly probe the low-energy\n(0.5--5 meV) electrodynamics of the charge-ordered manganite\nPr$_{0.7}$Ca$_{0.3}$MnO$_3$. We revealed the existence of a finite peak\nstructure around 2--3 meV well below the charge gap $\\sim300$ meV. In analogy\nto the low-energy optical properties of the well-studied low-dimensional\nmaterials, we attributed this observed structure to the collective excitation\nmode arising from the charge-density-wave condensate. This finding provides the\nimportance role of the quasi-one dimensional nature of the charge and orbital\nordering in Pr$_{0.7}$Ca$_{0.3}$MnO$_3$.",
        "category": "cond-mat"
    },
    {
        "text": "The random model for simulation of the growth of small populations: The probability of the survival of the population of individuals of both\nsexes of given mature age, procreation rate and structure stability has been\nsearched in the numerical experiment. The populations with long period of\nreproduction and the high rate of procreation and without social mobility have\nthe most chance to survive. The populations with the late mature age and high\nmobility dies out. The fertility rate of simple reconstruction of generations\nobtained in the model (2.8) is close to the value for a human being (2.1).",
        "category": "cond-mat"
    },
    {
        "text": "Modelling of field-effect transistors based on 2D materials targeting\n  high-frequency applications: New technologies are necessary for the unprecedented expansion of\nconnectivity and communications in the modern technological society. The\nspecific needs of wireless communication systems in 5G and beyond, as well as\ndevices for the future deployment of Internet of Things has caused that the\nInternational Technology Roadmap for Semiconductors, which is the strategic\nplanning document of the semiconductor industry, considered since 2011,\ngraphene and related materials (GRMs) as promising candidates for the future of\nelectronics. Graphene, a one-atom-thick of carbon, is a promising material for\nhigh-frequency applications due to its intrinsic superior carrier mobility and\nvery high saturation velocity. These exceptional carrier transport properties\nsuggest that GRM-based field-effect transistors could potentially outperform\nother technologies.\n  This thesis presents a body of work on the modelling, performance prediction\nand simulation of GRM-based field-effect transistors and circuits. The main\ngoal of this work is to provide models and tools to ease the following issues:\n(i) gaining technological control of single layer and bilayer graphene devices\nand, more generally, devices based on 2D materials, (ii) assessment of\nradio-frequency (RF) performance and microwave stability, (iii) benchmarking\nagainst other existing technologies, (iv) providing guidance for device and\ncircuit design, (v) simulation of circuits formed by GRM-based transistors.",
        "category": "cond-mat"
    },
    {
        "text": "The Individual and Collective Effects of Exact Exchange and Dispersion\n  Interactions on the Ab Initio Structure of Liquid Water: In this work, we report the results of a series of density functional theory\n(DFT) based ab initio molecular dynamics (AIMD) simulations of ambient liquid\nwater using a hierarchy of exchange-correlation (XC) functionals to investigate\nthe individual and collective effects of exact exchange (Exx), via the PBE0\nhybrid functional, non-local vdW/dispersion interactions, via a fully\nself-consistent density-dependent dispersion correction, and approximate\nnuclear quantum effects (aNQE), via a 30 K increase in the simulation\ntemperature, on the microscopic structure of liquid water. Based on these AIMD\nsimulations, we found that the collective inclusion of Exx, vdW, and aNQE as\nresulting from a large-scale AIMD simulation of (H$_2$O)$_{128}$ at the\nPBE0+vdW level of theory, significantly softens the structure of ambient liquid\nwater and yields an oxygen-oxygen structure factor, $S_{\\rm OO}(Q)$, and\ncorresponding oxygen-oxygen radial distribution function, $g_{\\rm OO}(r)$, that\nare now in quantitative agreement with the best available experimental data.\nThis level of agreement between simulation and experiment as demonstrated\nherein originates from an increase in the relative population of water\nmolecules in the interstitial region between the first and second coordination\nshells, a collective reorganization in the liquid phase which is facilitated by\na weakening of the hydrogen bond strength by the use of the PBE0 hybrid XC\nfunctional, coupled with a relative stabilization of the resultant disordered\nliquid water configurations by the inclusion of non-local vdW/dispersion\ninteractions.",
        "category": "cond-mat"
    },
    {
        "text": "Stable multispeed lattice Boltzmann methods: We demonstrate how to produce a stable multispeed lattice Boltzmann method\n(LBM) for a wide range of velocity sets, many of which were previously thought\nto be intrinsically unstable. We use non-Gauss--Hermitian cubatures. The method\noperates stably for almost zero viscosity, has second-order accuracy,\nsuppresses typical spurious oscillation (only a modest Gibbs effect is present)\nand introduces no artificial viscosity. There is almost no computational cost\nfor this innovation.\n  DISCLAIMER: Additional tests and wide discussion of this preprint show that\nthe claimed property of coupled steps: no artificial dissipation and the\nsecond-order accuracy of the method are valid only on sufficiently fine grids.\nFor coarse grids the higher-order terms destroy coupling of steps and\nadditional dissipation appears.\n  The equations are true.",
        "category": "cond-mat"
    },
    {
        "text": "Gapless spin liquid ground state of spin-1/2 $J_1$-$J_2$ Heisenberg\n  model on square lattices: The spin-1/2 $J_1$-$J_2$ Heisenberg model on square lattices are investigated\nvia the finite projected entangled pair states (PEPS) method. Using the\nrecently developed gradient optimization method combining with Monte Carlo\nsampling techniques, we are able to obtain the ground states energies that are\ncompetitive to the best results. The calculations show that there is no N\\'eel\norder, dimer order and plaquette order in the region of 0.42 $\\lesssim\nJ_2/J_1\\lesssim$ 0.6, suggesting a single spin liquid phase in the intermediate\nregion. Furthermore, the calculated staggered spin, dimer and plaquette\ncorrelation functions all have power law decay behaviours, which provide strong\nevidences that the intermediate nonmagnetic phase is a single gapless spin\nliquid state.",
        "category": "cond-mat"
    },
    {
        "text": "Bose-Condensed Gases in a 1D Optical Lattice at Finite Temperatures: We study equilibrium properties of Bose-Condensed gases in a one-dimensional\n(1D) optical lattice at finite temperatures. We assume that an additional\nharmonic confinement is highly anisotropic, in which the confinement in the\nradial directions is much tighter than in the axial direction. We derive a\nquasi-1D model of the Gross-Pitaeavkill equation and the Bogoliubov equations,\nand numerically solve these equations to obtain the condensate fraction as a\nfunction of the temperature.",
        "category": "cond-mat"
    },
    {
        "text": "Surface structures of the magnetostrictive D03-Fe3Ga(001): First-principles total energy calculations and experimental measurements were\nperformed to study the surface reconstructions of the magnetostrictive Fe3Ga\nalloy. The magnetostrictive behavior was evaluated in the bulk by compressing\nand stretching its lattice parameter. Results demonstrate two thermodynamically\nstable surfaces, the 1x1 and 3x1 reconstructions. The 1x1 is an ideally FeGa\nterminated surface whereas the 3x1 is also FeGa terminated but it has a\nfirst-layer Fe atom substituted by a Ga atom every three unit-cells, forming\nstripe-like domain patterns. Tersoff-Hamann scanning tunneling microscopy\nsimulations were obtained and compared with experimental results. We found good\nagreement between theory and experiment, in which the distance between rows is\n~1.23 nm. The substrate-induced strain increases the stability of the 3x1\nreconstruction. Here we have demonstrated that Ga/Fe atomic exchanges lead to\nthe stripe-like domain patterns. Clarification of the atomic reconstructions\npresent on the magnetostrictive Fe3Ga alloys is an important step towards the\nunderstanding of its surfaces and poses this system as a potential candidate to\nbe used as part of perpendicular magnetic tunnel junctions due to the existing\nperpendicular magnetic anisotropy effect when grown on different substrates.",
        "category": "cond-mat"
    },
    {
        "text": "Magneto-transport of large CVD-grown graphene: We present magnetoresistance measurements on large scale monolayer graphene\ngrown by chemical vapor deposition (CVD) on copper. The graphene layer was\ntransferred onto SiO2/Si via PMMA and thermal release tape for transport\nmeasurements. The resulting centimeter-sized graphene samples were measured at\ntemperatures down to 30mK in a magnetic field. We observe a very sharp peak in\nresistance at zero field, which is well fitted by weak localization theory. The\nsamples exhibit conductance fluctuations symmetric in field, which are\nattributed to ensemble averaged conductance fluctuations due to large scale\ninhomogeneities consistent with the grain boundaries of copper during the CVD\ngrowth.",
        "category": "cond-mat"
    },
    {
        "text": "Linear and quadratic magnetoresistance in the semimetal SiP2: Multiple mechanisms for extremely large magnetoresistance (XMR) found in many\ntopologically nontrivial/trivial semimetals have been theoretically proposed,\nbut experimentally it is unclear which mechanism is responsible in a particular\nsample. In this article, by the combination of band structure calculations,\nnumerical simulations of magnetoresistance (MR), Hall resistivity and de\nHaas-van Alphen (dHvA) oscillation measurements, we studied the MR anisotropy\nof SiP$_{2}$ which is verified to be a topologically trivial, incomplete\ncompensation semimetal. It was found that as magnetic field, $H$, is applied\nalong the $a$ axis, the MR exhibits an unsaturated nearly linear $H$\ndependence, which was argued to arise from incomplete carriers compensation.\nFor the $H$ $\\parallel$ [101] orientation, an unsaturated nearly quadratic $H$\ndependence of MR up to 5.88 $\\times$ 10$^{4}$$\\%$ (at 1.8 K, 31.2 T) and\nfield-induced up-turn behavior in resistivity were observed, which was\nsuggested due to the existence of hole open orbits extending along the $k_{x}$\ndirection. Good agreement of the experimental results with the simulations\nbased on the calculated Fermi surface (FS) indicates that the topology of FS\nplays an important role in its MR.",
        "category": "cond-mat"
    },
    {
        "text": "Criticality in Cell Adhesion: We illuminate the many-body effects underlying the structure, formation, and\ndissolution of cellular adhesion domains in the presence and absence of forces.\nWe consider mixed Glauber-Kawasaki dynamics of a two-dimensional model of\nnearest-neighbor interacting adhesion bonds with intrinsic binding-affinity\nunder the action of a shared pulling or pushing force. We consider adhesion\nbonds that are immobile due to being anchored to the underlying cytoskeleton as\nwell as adhesion molecules that are transiently diffusing. Highly accurate\nanalytical results are obtained on the pair-correlation level of the\nBethe-Guggenheim approximation for the complete thermodynamics and kinetics of\nadhesion clusters of any size, including the thermodynamic limit. A new kind of\ndynamical phase transition is uncovered -- the mean formation and dissolution\ntimes per adhesion bond change discontinuously with respect to the\nbond-coupling parameter. At the respective critical points cluster formation\nand dissolution are fastest, while the statistically dominant transition path\nundergoes a qualitative change -- the entropic barrier to complete\nbinding/unbinding is rate-limiting below, and the phase transition between\ndense and dilute phases above the dynamical critical point. In the context of\nthe Ising model the dynamical phase transition reflects a first-order\ndiscontinuity in the magnetization-reversal time. Our results provide a\npotential explanation for the mechanical regulation of cell adhesion, and\nsuggest that the quasi-static and kinetic response to changes in the membrane\nstiffness or applied forces is largest near the statical and dynamical critical\npoint, respectively.",
        "category": "cond-mat"
    },
    {
        "text": "Monte Carlo Simulation of Liquid-Crystal Alignment and of Chiral\n  Symmetry-Breaking: We carry out Monte Carlo simulations to investigate the effect of molecular\nshape on liquid-crystal order. In our approach, each model mesogen consists of\nseveral soft spheres bonded rigidly together. The arrangement of the spheres\nmay be straight (to represent uniaxial molecules), Z-shaped (for biaxial\nmolecules), or banana-shaped (for bent-core molecules). Using this approach, we\ninvestigate the alignment of the nematic phase by substrates decorated with\nparallel ridges. We compare results for wide and narrow ridge spacing and\nexamine local order near the substrates, and show that our results are\nconsistent with the predictions of Landau theory. We also investigate chiral\nsymmetry-breaking in systems of bent-core molecules. We find a chiral\ncrystalline phase as well as a nonchiral smectic-A phase, but not a chiral\nsmectic-C phase.",
        "category": "cond-mat"
    },
    {
        "text": "Superfluidity and magnetism in multicomponent ultracold fermions: We study the interplay between superfluidity and magnetism in a\nmulticomponent gas of ultracold fermions. Ward-Takahashi identities constrain\npossible mean-field states describing order parameters for both pairing and\nmagnetization. The structure of global phase diagrams arises from competition\namong these states as functions of anisotropies in chemical potential, density,\nor interactions. They exhibit first and second order phase transition as well\nas multicritical points, metastability regions, and phase separation. We\ncomment on experimental signatures in ultracold atoms.",
        "category": "cond-mat"
    },
    {
        "text": "Improved performance in quantum transport calculations: A\n  divide-and-conquer method based on S-matrices: We propose a divide-and-conquer algorithm to find recursively the Scattering\nmatrix of general tight-binding structures. The Scattering matrix allows a\ndirect calculation of transport properties in mesoscopic systems by using the\nLandauer formula. The method is exact, and by analyzing the performance of the\nalgorithm in square, triangular and honeycomb lattices, we show a significant\nimprovement in comparison to other state-of-the-art recursive and non-recursive\nmethods.",
        "category": "cond-mat"
    },
    {
        "text": "Near-zero-field microwave-free magnetometry with nitrogen-vacancy\n  centers in nanodiamonds: We study the fluorescence of nanodiamond ensembles as a function of static\nexternal magnetic field and observe characteristic dip features close to the\nzero field with potential for magnetometry applications. We analyze the\ndependence of the features width and contrast of the feature on the size of the\ndiamond (in the range 30 nm to 3 um) and on the strength of a bias magnetic\nfield applied transversely to the field being scanned. We also perform\noptically detected magnetic resonance (ODMR) measurements to quantify the\nstrain splitting of the zero-field ODMR resonance across various nanodiamond\nsizes and compare it with the width and contrast measurements of the zero-field\nfluorescence features for both nanodiamonds and bulk samples. The observed\nproperties provide compelling evidence of cross-relaxation effects in the NV\nsystem occurring close to zero magnetic fields. Finally, the potential of this\ntechnique for use in practical magnetometry is discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Evaluation of Neel temperatures from fully self-consistent\n  broken-symmetry GW and high-temperature expansion: application to cubic\n  transition-metal oxides: Using fully self-consistent thermal broken-symmetry GW we construct effective\nmagnetic Heisenberg Hamiltonians for a series of transition metal oxides (NiO,\nCoO, FeO, MnO), capturing a rigorous but condensed description of the magnetic\nstates. Then applying high-temperature expansion, we find the decomposition\ncoefficients for spin susceptibility and specific heat. The radius of\nconvergence of the found series determine the Neel temperature. The NiO, CoO,\nand FeO contain a small ferromagnetic interaction between the nearest neighbors\n(NN) and the dominant antiferromagnetic interaction between the next-nearest\nneighbors (NNN). For them the derived Neel temperatures are in a good agreement\nwith experiment. The case of MnO is different because both NN and NNN couplings\nare antiferromagnetic and comparable in magnitude, for which the error in the\nestimated Neel temperature is larger, which is a signature of additional\neffects not captured by electronic structure calculations.",
        "category": "cond-mat"
    },
    {
        "text": "Avoided metallicity in a hole-doped Mott insulator on a triangular\n  lattice: Charge carrier doping of a Mott insulator is known to give rise to a wide\nvariety of exotic emergent states, from high-temperature superconductivity to\nvarious charge, spin, and orbital orders. The physics underpinning their\nevolution is, however, poorly understood. A major challenge is the chemical\ncomplexity associated with traditional routes to the addition or removal of\ncarriers. Here, we study the Mott insulating CrO$_2$ layer of the delafossite\noxide PdCrO$_2$, where an intrinsic polar catastrophe provides a clean route to\ninduce substantial doping of the surface layer. Despite this, from scanning\ntunneling microscopy and angle-resolved photoemission, we find that the surface\nretains an insulating character, but with a modified electronic structure and\nthe development of a short-range ordered state with a distinct\n$(\\sqrt{7}\\times\\sqrt{7})\\mathrm{R}\\pm 19.1^\\circ$ periodicity. From density\nfunctional theory, we demonstrate how this reflects the formation of an\nintricate charge disproportionation that results in an insulating ground state\nof the surface layer that is disparate from the hidden Mott insulator found in\nthe bulk. By applying voltage pulses to the surface layer, we induce\nsubstantial local modifications to this state, which we find relax on a time\nscale of tens of minutes, pointing to a glassy nature of the\ncharge-disproportionated insulator realised here.",
        "category": "cond-mat"
    },
    {
        "text": "Short-time dynamics in active systems: the Vicsek model: We study the short-time dynamics (STD) of the Vicsek model with vector noise.\nThe study of STD has proved to be very useful in the determination of the\ncritical point, critical exponents, and spinodal points in equilibrium phase\ntransitions. Here we aim to test its applicability in active systems. We find\nthat, despite the essential non-equilibrium characteristics of the VM (absence\nof detailed balance, activity), the STD presents qualitatively the same\nphenomenology as in equilibrium systems. From the STD one can distinguish\nwhether the transition is continuous or discontinuous (which we have checked\nalso computing the Binder cumulant). When the transition is continuous, one can\ndetermine the critical point and the critical exponents.",
        "category": "cond-mat"
    },
    {
        "text": "Ostwald ripening of aqueous microbubble solutions: Bubble solutions are of growing interest because of various technological\napplications in surface cleaning, water treatment, and agriculture. However,\ntheir physicochemical properties such as the stability and interfacial charge\nof bubbles are not fully understood yet. In this study, the kinetics of radii\nin aqueous microbubble solutions are experimentally investigated, and the\nresults are discussed in the context of Ostwald ripening. The obtained\ndistributions of bubble radii scaled by mean radius and total number were found\nto be time-independent during the observation period. Image analysis of radii\nkinetics revealed that the average growth and shrinkage speed of each bubble is\ngoverned by diffusion-limited Ostwald ripening, and the kinetic coefficient\ncalculated using the available physicochemical constants in literature\nquantitatively agrees with the experimental data. Furthermore, the cube of mean\nradius and mean volume exhibit a linear time evolution in agreement with the\nLifshitz-Slezov-Wagner (LSW) theory. The coefficients are slightly larger than\nthose predicted using the LSW theory, which can be qualitatively explained by\nthe effect of finite volume fraction. Finally, the slow down and pinning of\nradius in the shrinkage dynamics of small microbubbles are discussed in detail.",
        "category": "cond-mat"
    },
    {
        "text": "Impact of AC Magnetic Field on Decoherence of Quantum Dot based Single\n  Spin Qubit System: Quantum dot-based spin qubits are resilient towards charge noise and are\naffected by magnetic noise only. However, environmental interaction leads to\ndecoherence in these qubit systems. The external control parameters are\ndirectly related to the magnitude of decoherence. This in turn limits the range\nof values of those parameters for which operations can be done with high\nfidelity. In this work, using a model of quantum dot spin qubit system, we\ninvestigate the impact of varying ac magnetic fields on suppression of\ndecoherence. We report an increment in the usable range of static magnetic\nfield value using our technique.",
        "category": "cond-mat"
    },
    {
        "text": "Active and Passive Transport of Cargo in a Corrugated Channel: A Lattice\n  Model Study: Inside cells, cargos such as vesicles and organelles are transported by\nmolecular motors to their correct locations via active motion on cytoskeletal\ntracks and passive, Brownian diffusion. During the transportation of cargos,\nmotor-cargo complexes (MCC) navigate the confining and crowded environment of\nthe cytoskeletal network and other macromolecules. Motivated by this, we study\na minimal two-state model of motor-driven cargo transport in confinement and\npredict transport properties that can be tested in experiments. We assume that\nthe motion of the MCC is directly affected by the entropic barrier due to\nconfinement if it is in the passive, unbound state, but not in the active,\nbound state where it moves with a constant bound velocity. We construct a\nlattice model based on a Fokker Planck description of the two-state system,\nstudy it using a kinetic Monte Carlo method and compare our numerical results\nwith analytical expressions for a mean field limit. We find that the effect of\nconfinement strongly depends on the bound velocity and the binding kinetics of\nthe MCC. Confinement effectively reduces the effective diffusivity and average\nvelocity, except when it results in an enhanced average binding rate and\nthereby leads to a larger average velocity than when unconfined.",
        "category": "cond-mat"
    },
    {
        "text": "Supersolidity from defect-condensation in the extended boson Hubbard\n  model: We study the ground state phase diagram of the hard-core extended boson\nHubbard model on the square lattice with both nearest- (nn) and\nnext-nearest-neighbor (nnn) hopping and repulsion, using Gutzwiller mean field\ntheory and quantum Monte Carlo simulations. We observe the formation of\nsupersolid states with checkerboard, striped, and quarter-filled crystal\nstructures, when the system is doped away from commensurate fillings. In the\nstriped supersolid phase, a strong anisotropy in the superfluid density is\nobtained from the simulations; however, the transverse component remains\nfinite, indicating a true two-dimensional superflow. We find that upon doping,\nthe striped supersolid transitions directly into the supersolid with\nquarter-filled crystal structure, via a first-order stripe melting transition.",
        "category": "cond-mat"
    },
    {
        "text": "High pressure layered structure of carbon disulfide: Solid CS$_{2}$ is superficially similar to CO$_{2}$, with the same $Cmca$\nmolecular crystal structure at low pressures, which has suggested similar\nphases also at high pressures. We carried out an extensive first principles\nevolutionary search in order to identify the zero temperature lowest enthalpy\nstructures of CS$_{2}$ for increasing pressure up to 200\\,GPa. Surprisingly,\nthe molecular $Cmca$ phase does not evolve into $\\beta$-cristobalite as in\nCO$_{2}$, but transforms instead into phases HP2 and HP1, both recently\ndescribed in high pressure SiS$_{2}$. HP1 in particular, with a wide stability\nrange, is a layered $P2_{1}/c$ structure characterized by pairs of edge-sharing\ntetrahedra, and theoretically more robust than all other CS$_{2}$ phases\ndiscussed so far. Its predicted Raman spectrum and pair correlation function\nagree with experiment better than those of $\\beta$-cristobalite, and further\ndifferences are predicted between their respective IR spectra. The band gap of\nHP1-CS$_{2}$ is calculated to close under pressure yielding an insulator-metal\ntransition near 50 GPa in agreement with experimental observations. However,\nthe metallic density of states remains modest above this pressure, suggesting a\ndifferent origin for the reported superconductivity.",
        "category": "cond-mat"
    },
    {
        "text": "Double-dot charge transport in Si single electron/hole transistors: We studied transport through ultra-small Si quantum dot transistors\nfabricated from silicon-on-insulator wafers. At high temperatures, 4K<T<100K,\nthe devices show single-electron or single-hole transport through the\nlithographically defined dot. At T<4K, current through the devices is\ncharacterized by multidot transport. From the analysis of the transport in\nsamples with double-dot characteristics, we conclude that extra dots are formed\ninside the thermally grown gate oxide which surrounds the lithographically\ndefined dot.",
        "category": "cond-mat"
    },
    {
        "text": "Collective phenomena in granular and atmospheric electrification: In clouds of suspended particles (grains, droplets, spheres, crystals, etc.),\ncollisions electrify the particles and the clouds, producing large electric\npotential differences over large scales. This is seen most spectacularly in the\natmosphere as lighting in thunderstorms, thundersnow, dust storms, and volcanic\nash plumes where multi-million-volt potential differences over scales of\nkilometers can be produced, but it is a general phenomenon in granular systems\nas a whole. The electrification process is not well understood, especially for\nelectrification of insulating particles of the same material. To investigate\nthe relative importances of particle properties (material, size, etc.) and\ncollective phenomena (behaviors of systems at large scales not easily predicted\nfrom local dynamics) in granular and atmospheric electrification, we used a\ntable-top experiment that mechanically shakes particles inside a cell where we\nmeasure the macroscopic electric field between the electrically conducting end\nplates. The measured electric fields are a result of capacitive coupling and\ndirect charge transfer between the particles and the plates. Using a diverse\nrange of mono-material particle sets (plastics, ceramic, glass, and metals), we\nfound that all our particle materials electrify and show similar dynamics with\nlong time-scale temporal variation and an electric field amplitude that depends\non the particle quantity in a complex way. These results suggest that while\nparticle properties do matter like previous investigations have shown,\nmacroscopic electrification of solids is relatively material agnostic and large\nscale collective phenomena play a major role.",
        "category": "cond-mat"
    },
    {
        "text": "Tunable spin and valley excitations of correlated insulators in\n  $\u0393$-valley moir\u00e9 bands: Moir\\'e superlattices formed from transition metal dichalcogenides (TMDs)\nhave been shown to support a variety of quantum electronic phases that are\nhighly tunable using applied electromagnetic fields. While the valley character\nof the low-energy states dramatically affects optoelectronic properties in the\nconstituent TMDs, this degree of freedom has yet to be fully explored in\nmoir\\'e systems. Here, we establish twisted double bilayer WSe$_2$ as an\nexperimental platform to study electronic correlations within $\\Gamma$-valley\nmoir\\'e bands. Through a combination of local and global electronic\ncompressibility measurements, we identify charge-ordered phases at multiple\ninteger and fractional moir\\'e band fillings $\\nu$. By measuring the magnetic\nfield dependence of their energy gaps and the chemical potential upon doping,\nwe reveal spin-polarized ground states with novel spin polaron quasiparticle\nexcitations. In addition, an applied displacement field allows us to realize a\nnew mechanism of metal-insulator transition at $\\nu = -1$ driven by tuning\nbetween $\\Gamma$- and $K$-valley moir\\'e bands. Together, our results\ndemonstrate control over both the spin and valley character of the correlated\nground and excited states in this system.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-to-Orbital Angular Momentum Conversion in Semiconductor\n  Microcavities: We experimentally demonstrate a technique for the generation of optical beams\ncarrying orbital angular momentum using a planar semiconductor microcavity.\nDespite being isotropic systems, the transverse electric - transverse magnetic\n(TE-TM) polarization splitting featured by semiconductor microcavities allows\nfor the conversion of the circular polarization of an incoming laser beam into\nthe orbital angular momentum of the transmitted light field. The process\nimplies the formation of topological entities, a pair of optical half-vortices,\nin the intracavity field.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetoelectric coupling in multiferroic CFO/BCTSn core shell nanofibers\n  elaborated by co-axial electrospinning method: Multiferroic CoFe2O4-Ba0.95Ca0.05Ti0.89Sn0.11O3 core-shell nanofibers\n(CFO@BCTSn NFs) were synthesized by a sol-gel co-axial electrospinning\ntechnique. The scanning electron microscope and transmission electron\nmicroscope were used to check nanofibers' core-shell structure/configuration.\nX-ray diffraction and a high-resolution transmission electron microscope were\nused to confirm the spinel structure of CFO and the perovskite structure of\nBCTSn. The magnetic character of the resultant CFO@BCTSn NFs was determined by\nSQUID magnetometry. The piezoelectricity was verified using piezo-response\nforce microscopy, which revealed an entirely covered ferroelectric shell\noutline, in accordance with SEM and TEM observations. The magnetoelectric (ME)\ncoefficient was measured as a function of the applied external DC magnetic\nfield. The maximum ME coefficient obtained for the CFO@BCTSn NFs was 346 mV\ncm-1 Oe-1. The high magnetoelectric coupling suggests that CFO@BCTSn NFs could\nbe a promising candidate for magnetic field sensor and magnetoelectric device\napplications.",
        "category": "cond-mat"
    },
    {
        "text": "Bayesian Inference in the Scaling Analysis of Critical Phenomena: To determine the universality class of critical phenomena, we propose a\nmethod of statistical inference in the scaling analysis of critical phenomena.\nThe method is based on Bayesian statistics, most specifically, the Gaussian\nprocess regression. It assumes only the smoothness of a scaling function, and\nit does not need a form. We demonstrate this method for the finite-size scaling\nanalysis of the Ising models on square and triangular lattices. Near the\ncritical point, the method is comparable in accuracy to the least-square\nmethod. In addition, it works well for data to which we cannot apply the\nleast-square method with a polynomial of low degree. By comparing the data on\ntriangular lattices with the scaling function inferred from the data on square\nlattices, we confirm the universality of the finite-size scaling function of\nthe two-dimensional Ising model.",
        "category": "cond-mat"
    },
    {
        "text": "Ferromagnetic metallic Sr-rich Ln$_{1/2}$A$_{1/2}$CoO$_3$ cobaltites\n  with spontaneous spin rotation: The Pr$_{0.50}$Sr$_{0.5}$0CoO$_3$ perovskite exhibits unique\nmagnetostructural properties among the rest of ferromagnetic/metallic\nLn$_{0.50}$Sr$_{0.50}$CoO$_3$ compounds. The sudden orthorhombic-tetragonal\n(Imma $\\to$ I4/mcm) structural transition produces an unusual magnetic behavior\nversus temperature and external magnetic fields. In particular, the symmetry\nchange is responsible for a spontaneous spin rotation in this metallic oxide.\nWe have studied half-doped Ln$_{0.50}$(Sr$_{1-x}$A$_x$)$_{0.50}$CoO$_3$\ncobaltites varying the ionic radius rA of A-site cations (divalent cations and\nlanthanides) in order to complete the T-rA phase diagram. The influence of the\nstructural distortion and the A-cations size for the occurrence of a\nspontaneous spin reorientation in the metallic state has been investigated. As\nthe reorientation of the magnetization is driven by the temperature induced\ncollapse of the orthorhombic distortion, a careful investigation of the\nstructural symmetry is presented varying the structural distortion of the\nSr-rich half-doped cobaltites by means of both compositional and temperature\nchanges. The region in the phase diagram of these perovskites where the phase\nof magnetic symmetry Fm'm'm replaces that of Im'm'a symmetry was determined in\nthis family of ferromagnetic/metallic cobaltites. In that region the\nmagnetization direction has rotated 45 degrees within the a-b plane with\nrespect to the second.",
        "category": "cond-mat"
    },
    {
        "text": "Interplay of Hidden Orbital Order and Superconductivity in CeCoIn5: Visualizing atomic-orbital degrees of freedom is a frontier challenge in\nscanned microscopy. Some types of orbital order are virtually imperceptible to\nnormal scattering techniques because they do not reduce the overall crystal\nlattice symmetry. A good example is dxz/dyz ({\\pi},{\\pi}) orbital order in\ntetragonal lattices. For enhanced detectability, here we consider the\nquasiparticle scattering interference (QPI) signature of such ({\\pi},{\\pi})\norbital order in both normal and superconducting phases. The theory reveals\nthat sublattice-specific QPI signatures generated by the orbital order should\nemerge strongly in the superconducting phase. Sublattice-resolved QPI\nvisualization in superconducting CeCoIn5 then reveals two orthogonal QPI\npatterns at lattice-substitutional impurity atoms. We analyze the energy\ndependence of these two orthogonal QPI patterns and find the intensity peaked\nnear E=0, as predicted when such ({\\pi}) orbital order is inte,{\\pi}rtwined\nwith d-wave superconductivity. Sublattice-resolved superconductive QPI\ntechniques thus represent a new approach for study of hidden orbital order.",
        "category": "cond-mat"
    },
    {
        "text": "Pair Tunneling in Semiconductor Quantum Dots: We propose here a model for the pair tunneling states observed by Ashoori and\nco-workers (Phys. Rev. Lett. {\\bf 68}, 3088 (1992)) in GaAs quantum dots. We\nshow that while GaAs is a weakly-polar semiconductor, coupling to optical\nphonons is sufficiently strong to mediate a negative-U pairing state. The\nphysical potential in which the two electrons are bound can be composed of a Si\nimpurity and a parabolic well that originates from the potential created by the\n$\\delta-$dopants in the backing layer of the dot. Such a pair state breaks up\nat moderate magnetic field strengths ($\\approx$ 2 T), as is seen\nexperimentally, and is unstable when the confining radius of the dot is smaller\nthan $\\approx 400$\\AA.",
        "category": "cond-mat"
    },
    {
        "text": "Mpemba effect in molecular gases under nonlinear drag: We look into the Mpemba effect---the initially hotter sample cools\nsooner---in a molecular gas with nonlinear viscous drag. Specifically, the gas\nparticles interact among them via elastic collisions and also with a background\nfluid at equilibrium. Thus, within the framework of kinetic theory, our gas is\ndescribed by an Enskog--Fokker--Planck equation. The analysis is carried out in\nthe first Sonine approximation, in which the evolution of the temperature is\ncoupled to that of the excess kurtosis. This coupling leads to the emergence of\nthe Mpemba effect, which is observed in an early stage of the relaxation and\nwhen the initial temperatures of the two samples are close enough. This allows\nfor the development of a simple theory, linearizing the temperature evolution\naround a reference temperature---namely the initial temperature closer to the\nasymptotic equilibrium value. The linear theory provides a semiquantitative\ndescription of the effect, including expressions for the crossover time and the\nmaximum temperature difference. We also discuss the limitations of our\nlinearized theory.",
        "category": "cond-mat"
    },
    {
        "text": "Critical Casimir torques and forces acting on needles in two spatial\n  dimensions: We investigate the universal orientation-dependent interactions between\nnon-spherical colloidal particles immersed in a critical solvent by studying\nthe instructive paradigm of a needle embedded in bounded two-dimensional Ising\nmodels at bulk criticality. For a needle in an Ising strip the interaction on\nmesoscopic scales depends on the width of the strip and the length, position,\nand orientation of the needle. By lattice Monte Carlo simulations we evaluate\nthe free energy difference between needle configurations being parallel and\nperpendicular to the strip. We concentrate on small but nonetheless mesoscopic\nneedle lengths for which analytic predictions are available for comparison. All\ncombinations of boundary conditions for the needles and boundaries are\nconsidered which belong to either the \"normal\" or the \"ordinary\" surface\nuniversality class, i.e., which induce local order or disorder, respectively.\nWe also derive exact results for needles of arbitrary mesoscopic length, in\nparticular for needles embedded in a half plane and oriented perpendicular to\nthe corresponding boundary as well as for needles embedded at the center line\nof a symmetric strip with parallel orientation.",
        "category": "cond-mat"
    },
    {
        "text": "Plastic Instabilities in Charged Granular Systems: Competition between\n  Elasticity and Electrostatics: Electrostatic theory preserves charges, but allows dipolar excitations.\nElasticity theory preserves dipoles, but allows quadrupolar (Eshelby like)\nplastic events. Charged amorphous granular systems are interesting in their own\nright; here we focus on their plastic instabilities and examine their\nmechanical response to external strain and to external electric field, to\nexpose the competition between elasticity and electrostatics. In this paper a\ngeneric model is offered, its mechanical instabilities are examined and a\ntheoretical analysis is presented. Plastic instabilities are discussed as\nsaddle-node bifurcations that can be fully understood in terms of eigenvalues\nand eigenfunctions of the relevant Hessian matrix. This system exhibits moduli\nthat describe how electric polarization and stress are influenced by strain and\nelectric field. Theoretical expression for these moduli are offered and\ncompared to the measurements in numerical simulations.",
        "category": "cond-mat"
    },
    {
        "text": "Interaction of chiral rafts in self-assembled colloidal membranes: Colloidal membranes are monolayer assemblies of rodlike particles that\ncapture the long-wavelength properties of lipid bilayer membranes on the\ncolloidal scale. Recent experiments on colloidal membranes formed by chiral\nrodlike viruses showed that introducing a second species of virus with\ndifferent length and opposite chirality leads to the formation of rafts ---\nmicron-sized domains of one virus species floating in a background of the other\nviruses [Sharma et al., Nature 513, 77 (2014)]. In this article we study the\ninteraction of such rafts using liquid crystal elasticity theory. By\nnumerically minimizing the director elastic free energy, we predict the tilt\nangle profile for both a single raft and two rafts in a background membrane,\nand the interaction between two rafts as a function of their separation. We\nfind that the chiral penetration depth in the background membrane sets the\nscale for the range of the interaction. We compare our results with the\nexperimental data and find good agreement for the strength and range of the\ninteraction. Unlike the experiments, however, we do not observe a complete\ncollapse of the data when rescaled by the tilt angle at the raft edge.",
        "category": "cond-mat"
    },
    {
        "text": "Absence of evidence of spin transport through amorphous\n  Y$_3$Fe$_5$O$_{12}$: Long-distance transport of spin information in insulators without long-range\nmagnetic order has been recently reported. Here, we perform a complete\ncharacterization of amorphous Y$_3$Fe$_5$O$_{12}$ (a-YIG) films grown on top of\nSiO$_2$. We confirm a clear amorphous structure and paramagnetic behavior of\nour a-YIG films, with semiconducting behavior resistivity that strongly decays\nwith increasing temperature. The non-local transport measurements show a signal\nwhich is not compatible with spin transport and can be attributed to the drop\nof the a-YIG resistivity caused by Joule heating. Our results emphasize that\nexploring spin transport in amorphous materials requires careful procedures in\norder to exclude the charge contribution from the spin transport signals.",
        "category": "cond-mat"
    },
    {
        "text": "Structure and oxidation kinetics of the Si(100)-SiO2 interface: We present first-principles calculations of the structural and electronic\nproperties of Si(001)-SiO2 interfaces. We first arrive at reasonable structures\nfor the c-Si/a-SiO2 interface via a Monte-Carlo simulated annealing applied to\nan empirical interatomic potential, and then relax these structures using\nfirst-principles calculations within the framework of density-functional\ntheory. We find a transition region at the interface, having a thickness on the\norder of 20\\AA, in which there is some oxygen deficiency and a corresponding\npresence of sub-oxide Si species (mostly Si^+2 and Si^+3). Distributions of\nbond lengths and bond angles, and the nature of the electronic states at the\ninterface, are investigated and discussed. The behavior of atomic oxygen in\na-SiO2 is also investigated. The peroxyl linkage configuration is found to be\nlower in energy than interstitial or threefold configurations. Based on these\nresults, we suggest a possible mechanism for oxygen diffusion in a-SiO2 that\nmay be relevant to the oxidation process.",
        "category": "cond-mat"
    },
    {
        "text": "Bright solitons in ultracold atoms: We review old and recent experimental and theoretical results on bright\nsolitons in Bose-Einstein condensates made of alkali-metal atoms and under\nexternal optical confinement. First we deduce the three-dimensional\nGross-Pitaevskii equation (3D GPE) from the Dirac-Frenkel action of interacting\nidentical bosons within a time-dependent Hartree approximation. Then we discuss\nthe dimensional reduction of the GPE from 3D to 1D, deriving the 1D GPE and\nalso the 1D nonpolynomial Schr\\\"odinger equation (1D NPSE). Finally, we analyze\nthe bright solition solutions of both 1D GPE and 1D NPSE and compare these\ntheoretical predictions with the available experimental data.",
        "category": "cond-mat"
    },
    {
        "text": "Heat release by controlled continuous-time Markov jump processes: We derive the equations governing the protocols minimizing the heat released\nby a continuous-time Markov jump process on a one-dimensional countable state\nspace during a transition between assigned initial and final probability\ndistributions in a finite time horizon. In particular, we identify the\nhypotheses on the transition rates under which the optimal control strategy and\nthe probability distribution of the Markov jump problem obey a system of\ndifferential equations of Hamilton-Bellman-Jacobi-type. As the state-space mesh\ntends to zero, these equations converge to those satisfied by the diffusion\nprocess minimizing the heat released in the Langevin formulation of the same\nproblem. We also show that in full analogy with the continuum case, heat\nminimization is equivalent to entropy production minimization. Thus, our\nresults may be interpreted as a refined version of the second law of\nthermodynamics.",
        "category": "cond-mat"
    },
    {
        "text": "Nanoparticles actively fragment armored droplets: Understanding the complexity of fragmentation processes is essential for\nregulating intercellular communication in mechanistic biology and developing\nnovel bottom-up approaches in a large range of multiphase flow processes. In\nthis context, self-fragmentation proceeds without any external mechanical\nenergy input allowing one to create efficiently micro- and nanodroplets. Here\nwe examine self-fragmentation in emulsion nanodroplets stabilized by solid\nparticles with different surface features. Mesoscopic modelling and accelerated\ndynamics simulations allow us to overcome the limitations of atomistic\nsimulations and offer detailed insight into the interplay between the evolution\nof the droplet shape and the particle finite-sized effects at the interface. We\nshow that finite-sized nanoparticles play an active role in the necking\nbreakup, behaving like nano-scale razors, and affect strongly the thermodynamic\nproperties of the system. The role played by the particles during\nself-fragmentation might be of relevance to multifunctional biomaterial design\nand tuning of signaling pathways in mechanistic biology.",
        "category": "cond-mat"
    },
    {
        "text": "Strongly coupled modes in a weakly driven micromechanical resonator: We demonstrate strong coupling between the flexural vibration modes of a\nclamped-clamped micromechanical resonator vibrating at low amplitudes. This\ncoupling enables the direct measurement of the frequency response via\namplitude- and phase modulation schemes using the fundamental mode as a\nmechanical detector. In the linear regime, a frequency shift of\n$\\mathrm{0.8\\,Hz}$ is observed for a mode with a line width of\n$\\mathrm{5.8\\,Hz}$ in vacuum. The measured response is well-described by the\nanalytical model based on the Euler-Bernoulli beam including tension.\nCalculations predict an upper limit for the room-temperature Q-factor of\n$\\mathrm{4.5\\times10^5}$ for our top-down fabricated micromechanical beam\nresonators.",
        "category": "cond-mat"
    },
    {
        "text": "Low-lying energy levels of a one-dimensional weakly interacting Bose gas\n  under zero boundary conditions: We diagonalize the second-quantized Hamiltonian of a one-dimensional Bose gas\nwith a nonpoint repulsive interatomic potential and zero boundary conditions.\nAt weak coupling the solutions for the ground-state energy $E_{0}$ and the\ndispersion law $E(k)$ coincide with the Bogoliubov solutions for a periodic\nsystem. In this case, the single-particle density matrix $F_{1}(x,x^{\\prime})$\nat $T=0$ is close to the solution for a periodic system and, at $T>0$, is\nsignificantly different from it. We also obtain that the wave function $\\langle\n\\hat{\\psi}(x,t) \\rangle$ of the effective condensate is close to a constant\n$\\sqrt{N_{0}/L}$ inside the system and vanishes on the boundaries (here,\n$N_{0}$ is the number of atoms in the effective condensate, and $L$ is the size\nof the system). We find the criterion of applicability of the method, according\nto which the method works for a finite system at very low temperature and with\na weak coupling (a weak interaction or a large concentration).",
        "category": "cond-mat"
    },
    {
        "text": "Touching is believing: interrogating organometal halide perovskite solar\n  cells at the nanoscale via scanning probe microscopy: Halide perovskite solar cells based on CH3NH3PbI3 and related materials have\nemerged as the most exciting development in the next generation photovoltaic\ntechnologies, yet the microscopic phenomena involving photo-carriers, ionic\ndefects, spontaneous polarization, and molecular vibration and rotation\ninteracting with numerous grains, grain boundaries, and interfaces are still\ninadequately understood. In fact, there is still need for an effective method\nto interrogate the local photovoltaic properties of halide perovskite solar\ncells that can be directly traced to their microstructures on one hand and\nlinked to their device performance on the other hand. In this perspective, we\npropose that scanning probe microscopy techniques have great potential to\nrealize such promises at the nanoscale, and highlight some of the recent\nprogresses and challenges along this line of investigation toward local probing\nof photocurrent, work function, ionic activities, polarization switching, and\nchemical degradation. We also emphasize the importance of multi-modality\nimaging, in-operando scanning, big data analysis, and multidisciplinary\ncollaboration for further studies toward fully understanding of these complex\nsystems.",
        "category": "cond-mat"
    },
    {
        "text": "Structural defects responsible for strain glassy transition in\n  Ni$_{50+x}$Ti$_{50-x}$: The strain glassy phase is produced by doping a small percentage of impurity\nin a martensitic alloy. Its ground state is conceived to consist of martensitic\nnano domains spatially separated from each other by a defect phase. The present\nstudy, by probing the local structure around the Ni and Ti in martensitic and\nstrain glassy compositions of Ni$_{50+x}$Ti$_{50-x}$, for the first time,\nidentifies the defect phase that is responsible for inhibiting the long range\nordering of the elastic strain vector leading to the formation of the strain\nglassy phase.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetic properties of bismuth-cobalt oxides doped by erbium: We synthesized bismuth - cobalt oxide doped by erbium with general formula\nBi3-xErxCoO3-y. Compound has structure of delta-form bismuth oxide. Magnetic\nproperties of the compound were measured by Faraday's method using quartz\nscales in the temperature range of 80-500 K. The magnetic susceptibility and\neffective magnetic moment were calculated.",
        "category": "cond-mat"
    },
    {
        "text": "Active colloid with externally induced periodic bipolar motility and its\n  cooperative motion: Active matter physics has been developed with various types of self-propelled\nparticles, including those with polar and bipolar motility and beyond. However,\nthe bipolar motions experimentally realized so far have been either random\nalong the axis or periodic at intrinsic frequencies. Here we report another\nkind of bipolar active particles, whose periodic bipolar self-propulsion is set\nexternally at a controllable frequency. We used Quincke rollers -- dielectric\nparticles suspended in a conducting liquid driven by an electric field -- under\nan AC electric field instead of the usually used DC field. Reciprocating motion\nof a single particle at the external frequency was observed experimentally and\ncharacterized theoretically as stable periodic motion. Experimentally, we\nobserved not only the reciprocating motion but also non-trivial active Brownian\nparticle (ABP)-like persistent motion in a long time scale. This resulted in a\nLorentzian spectrum around zero frequency, which is not accounted for by a\nsimple extension of the conventional model of Quincke rollers to the AC field.\nIt was found that ABP-like motion can be reproduced by considering the\ntop-bottom asymmetry in the experimental system. Moreover, we found a\nrotational diffusion coefficient much larger than the thermal one, as also\nreported in previous experiments, which may have resulted from roughness of the\nelectrode surface. We also found self-organized formation of small clusters,\nsuch as doublets and triplets, and characterized cooperative motion of\nparticles therein. The AC Quincke rollers reported here may serve as a model\nexperimental system of bipolar active matter, which appears to deserve further\ninvestigations.",
        "category": "cond-mat"
    },
    {
        "text": "Magneto-Stark and Zeeman effect as origin of second harmonic generation\n  of excitons in Cu$_2$O: We report on the experimental and theoretical investigation of\nmagnetic-field-induced second harmonic generation (SHG) and two-photon\nabsorption (TPA) of excited exciton states ($n \\geq 3$) of the yellow series in\nCu$_2$O. In this centrosymmetric material, SHG can occur due to constructive\ninterplay of electric dipole and electric quadrupole/magnetic dipole\ntransitions for light propagating along the low-symmetry directions [111] or\n[112]. By application of a magnetic field in Voigt configuration, SHG gets also\nallowed for excitation along the [110]-axis and even the high-symmetry cubic\ndirection [001]. Combining a symmetry analysis and a microscopic theory, we\nuncover the two key contributions to the magnetic-field-induced SHG: the Zeeman\neffect and the magneto-Stark effect. We demonstrate systematic dependencies of\nthe SHG intensity on the linear polarization angles of the ingoing fundamental\nlaser and the outgoing SHG beam. In general, the resulting contour plots in\ncombination with a symmetry analysis allow one to determine uniquely the\ncharacter of involved transitions. Moreover, we can separate in magnetic field\nthe Zeeman and the magneto-Stark effect through appropriate choice of the\nexperimental geometry and polarization configuration. We present a microscopic\ntheory of the second harmonic generation of excitons in a centrosymmetric cubic\nsemiconductor taking into account the symmetry and the band structure of\ncuprous oxide. Based on the developed microscopic theory we identify the main\ncontributions to the second-order nonlinear susceptibility of $S$-, $P$- and\n$D$-excitons. We analyze the redistribution of SHG intensities between the\nexcitonic states both in the absence and presence of the magnetic field and\nshow good agreement with the experimental data. With increasing exciton\nprincipal quantum number the magneto-Stark effect overpowers the influence of\nthe Zeeman effect.",
        "category": "cond-mat"
    },
    {
        "text": "Bright solitary waves of atomic Bose-Einstein condensates under rotation: We analyse the rotation of bright solitary waves formed of atomic\nBose-Einstein condensates with attractive atomic interactions. By employing a\nvariational technique and assuming an irrotational quadrupolar flow field, we\nmap out the variational solutions in the rotating frame. In particular, we show\nthat rotation has a considerable stabilising effect on the system,\nsignificantly raising the critical threshold for collapse of the bright\nsolitary waves.",
        "category": "cond-mat"
    },
    {
        "text": "Non-perturbative $J_{pd}$ model and ferromagnetism in dilute magnets: We calculate magnetic couplings in the $J_{pd}$ model for dilute magnets, in\norder both to identify the relevant parameters which control ferromagnetism and\nalso to bridge the gap between first principle calculations and model\napproaches. The magnetic exchange interactions are calculated\nnon-perturbatively and disorder in the configuration of impurities is treated\nexacly, allowing us to test the validity of effective medium theories.\n  Results differ qualitatively from those of weak coupling. In contrast to mean\nfield theory, increasing $J_{pd}$ may not favor high Curie temperatures: $T_C$\nscales primarily with the bandwidth. High temperature ferromagnetism at small\ndilutions is associated with resonant structure in the p-band. Comparison to\ndiluted magnetic semiconductors indicate that Ga(Mn)As has such a resonant\nstructure and thus this material is already close to optimality.",
        "category": "cond-mat"
    },
    {
        "text": "Topological states in normal and superconducting $p$-wave chains: We study a two-band model of fermions in a 1d chain with an antisymmetric\nhybridization that breaks inversion symmetry. We find that for certain values\nof its parameters, the $sp$-chain maps formally into a $p$-wave superconducting\nchain, the archetypical 1d system exhibiting Majorana fermions. The\neigenspectra, including the existence of zero energy modes in the topological\nphase, agree for both models. The end states too share several similarities in\nboth models, such as the behavior of the localization length, the non-trivial\ntopological index and robustness to disorder. However, we show by mapping the\n$s$- and $p$- fermions to two copies of Majoranas, that the excitations in the\nends of a finite $sp$ chain are indeed conventional fermions though endowed\nwith protected topological properties. Our results are obtained by a scattering\napproach in a semi-infinite chain with an edge defect treated within the\n$T$-matrix approximation. We augment the analytical results with exact\nnumerical diagonalization that allow us to extend our results to arbitrary\nparameters and also to disordered systems.",
        "category": "cond-mat"
    },
    {
        "text": "Suppressed compressibility of quantum Hall effect edge states in\n  epitaxial graphene on SiC: We determine conditions for the formation of compressible stripes near the\nquantum Hall effect (QHE) edges of top-gated epitaxial graphene on\nSi-terminated SiC (G/SiC) and compare those to graphene exfoliated onto\ninsulating substrate in the field-effect-transistor (GraFET) geometry.\n  For G/SiC, a large density of localised surface states on SiC just underneath\ngraphene layer and charge transfer between them lead both to doping of graphene\nand to screening of potential profile near its edge. This suppresses formation\nof compressible stripes near QHE edges in graphene, making them much narrower\nthan the corresponding compressible stripes in GraFETs.",
        "category": "cond-mat"
    },
    {
        "text": "The many-electron ground-state determines uniquely the potential in\n  Spin-Density-Functional Theory for non-collinear magnetism: Since Spin Density Functional Theory was first proposed, but also recently,\nexamples were constructed to show that a spin-potential may share its ground\nstate with other spin-potentials. In fact, for collinear magnetic fields and\nsystems with fixed magnetization, the mapping between potentials and ground\nstates is invertible, provided the magnetization is not saturated and that\nspin-potentials are determined within a spin-constant. We complete the proof\nthat the mapping is invertible also for non-collinear magnetic fields and\nsystems with more than one electron. We then discuss the non-collinear exchange\nand correlation energy functional and suggest improvements.",
        "category": "cond-mat"
    },
    {
        "text": "Substrate-Independent Catalyst-Free Synthesis of High-Purity Bi2Se3\n  Nanostructures: We describe a catalyst-free vapor-solid synthesis of bismuth selenide\n(Bi2Se3) nanostructures at ambient pressure with hydrogen as a carrier gas. The\nnanostructures were synthesized on glass, silicon and mica substrates and the\nmethod yields a variety of nanostructures: nanowires, nanoribbons,\nnanoplatelets and nanoflakes. The materials analysis shows high chemical purity\nin all cases, without sacrificing the crystalline structure of Bi2Se3.\nLow-temperature measurements of the nanostructures indicate contributions from\nthe surface states with a tunable carrier density. Samples synthesized on\nflexible mica substrates show no significant change in resistance upon bending,\nindicating robustness of as-grown Bi2Se3 nanostructures and their suitability\nfor device applications.",
        "category": "cond-mat"
    },
    {
        "text": "Electron-phonon coupling and superconductivity in LiB$_{1+x}$C$_{1-x}$: By means of the first-principles density-functional theory calculation and\nWannier interpolation, electron-phonon coupling and superconductivity are\nsystematically explored for boron-doped LiBC (i.e. LiB$_{1+x}$C$_{1-x}$), with\n$x$ between 0.1 and 0.9. Hole doping introduced by boron atoms is treated\nthrough virtual-crystal approximation. For the investigated doping\nconcentrations, our calculations show the optimal doping concentration\ncorresponds to 0.8. By solving the anisotropic Eliashberg equations, we find\nthat LiB$_{1.8}$C$_{0.2}$ is a two-gap superconductor, whose superconducting\ntransition temperature, T$_c$, may exceed the experimentally observed value of\nMgB$_2$. Similar to MgB$_2$, the two-dimensional bond-stretching $E_{2g}$\nphonon modes along $\\Gamma$-$A$ line have the largest contribution to\nelectron-phonon coupling. More importantly, we find that the first two acoustic\nphonon modes $B_1$ and $A_1$ around the midpoint of $K$-$\\Gamma$ line play a\nvital role for the rise of T$_c$ in LiB$_{1.8}$C$_{0.2}$. The origin of strong\ncouplings in $B_1$ and $A_1$ modes can be attributed to enhanced\nelectron-phonon coupling matrix elements and softened phonons. It is revealed\nthat all these phonon modes couple strongly with $\\sigma$-bonding electronic\nstates.",
        "category": "cond-mat"
    },
    {
        "text": "Microwave properties of superconducting $MgB_{2}$: Measurements of the $10GHz$ microwave surface resistance of dense $MgB_{2}$\nwire and pellet are reported. Significant improvements are observed in the wire\nwith reduction of porosity. The data lie substantially above the theoretical\nestimates for a pure BCS s-wave superconductor . However the $R_{s}(20K)$ of\nthe wire is an order of magnitude lower than that of polycrystal\n$YBa_{2}Cu_{3}O_{6.95}$ and matches with single crystal\n$YBa_{2}Cu_{3}O_{6.95}.$The results show promise for the use of $MgB_{2}$ in\nmicrowave applications.",
        "category": "cond-mat"
    },
    {
        "text": "Diagrammatic Monte Carlo study of the Fr\u00f6hlich polaron dispersion in\n  2D and 3D: We present results for the solution of the large polaron Fr\\\"ohlich\nHamiltonian in 3-dimensions (3D) and 2-dimensions (2D) obtained via the\nDiagrammatic Monte Carlo (DMC) method. Our implementation is based on the\napproach by Mishchenko [A.S. Mishchenko et al., Phys. Rev. B 62, 6317 (2000)].\nPolaron ground state energies and effective polaron masses are successfully\nbenchmarked with data obtained using Feynman's path integral formalism. By\ncomparing 3D and 2D data, we verify the analytically exact scaling relations\nfor energies and effective masses from 3D$\\to$2D, which provides a stringent\ntest for the quality of DMC predictions. The accuracy of our results is further\nproven by providing values for the exactly known coefficients in weak- and\nstrong coupling expansions. Moreover, we compute polaron dispersion curves\nwhich are validated with analytically known lower and upper limits in the small\ncoupling regime and verify the first order expansion results for larger\ncouplings, thus disproving previous critiques on the apparent incompatibility\nof DMC with analytical results and furnishing useful reference for a wide range\nof coupling strengths.",
        "category": "cond-mat"
    },
    {
        "text": "Unexpected upper critical dimension for spin glass models in a field\n  predicted by the loop expansion around the Bethe solution at zero temperature: The spin-glass transition in a field in finite dimension is analyzed directly\nat zero temperature using a perturbative loop expansion around the Bethe\nlattice solution. The loop expansion is generated by the $M$-layer construction\nwhose first diagrams are evaluated numerically and analytically. The\ngeneralized Ginzburg criterion reveals that the upper critical dimension below\nwhich mean-field theory fails is $D_U \\le 8$, at variance with the classical\nresult $D_U = 6$ yielded by finite-temperature replica field theory. Our\nexpansion around the Bethe lattice has two crucial differences with respect to\nthe classical one. The finite connectivity $z$ of the lattice is directly\nincluded from the beginning in the Bethe lattice, while in the classical\ncomputation the finite connectivity is obtained through an expansion in $1/z$.\nMoreover, if one is interested in the zero temperature ($T = 0$) transition,\none can directly expand around the $T = 0$ Bethe transition. The expansion\ndirectly at $T = 0$ is not possible in the classical framework because the\nfully connected spin glass does not have a transition at $T = 0$, being in the\nbroken phase for any value of the external field.",
        "category": "cond-mat"
    },
    {
        "text": "Epitaxy of Advanced Nanowire Quantum Devices: Semiconductor nanowires provide an ideal platform for various low-dimensional\nquantum devices. In particular, topological phases of matter hosting\nnon-Abelian quasi-particles can emerge when a semiconductor nanowire with\nstrong spin-orbit coupling is brought in contact with a superconductor. To\nfully exploit the potential of non-Abelian anyons for topological quantum\ncomputing, they need to be exchanged in a well-controlled braiding operation.\nEssential hardware for braiding is a network of single-crystalline nanowires\ncoupled to superconducting islands. Here, we demonstrate a technique for\ngeneric bottom-up synthesis of complex quantum devices with a special focus on\nnanowire networks having a predefined number of superconducting islands.\nStructural analysis confirms the high crystalline quality of the nanowire\njunctions, as well as an epitaxial superconductor-semiconductor interface.\nQuantum transport measurements of nanowire \"hashtags\" reveal Aharonov-Bohm and\nweak-antilocalization effects, indicating a phase coherent system with strong\nspin-orbit coupling. In addition, a proximity-induced hard superconducting gap\nis demonstrated in these hybrid superconductor-semiconductor nanowires,\nhighlighting the successful materials development necessary for a first\nbraiding experiment. Our approach opens new avenues for the realization of\nepitaxial 3-dimensional quantum device architectures.",
        "category": "cond-mat"
    },
    {
        "text": "Diffusion of Pt dimers on Pt(111): We report the results of a density-functional study of the diffusion of Pt\ndimers on the (111) surface of Pt. The calculated activation energy of 0.37 eV\nis in {\\em exact} agreement with the recent experiment of Kyuno {\\em et al.}\n\\protect{[}Surf. Sci. {\\bf 397}, 191 (1998)\\protect{]}. Our calculations\nestablish that the dimers are mobile at temperatures of interest for adatom\ndiffusion, and thus contribute to mass transport. They also indicate that the\ndiffusion path for dimers consists of a sequence of one-atom and (concerted)\ntwo-atom jumps.",
        "category": "cond-mat"
    },
    {
        "text": "Incommensurability and edge states in the one-dimensional S=1\n  bilinear-biquadratic model: Commensurate-incommensurate change on the one-dimensional S=1\nbilinear-biquadratic model (${\\cal H}(\\alpha)=\\sum_i \\{{\\bf S}_i\\cdot {\\bf\nS}_{i+1} +\\alpha ({\\bf S}_i\\cdot{\\bf S}_{i+1})^2\\}$) is examined. The gapped\nHaldane phase has two subphases (the commensurate Haldane subphase and the\nincommensurate Haldane subphase) and the commensurate-incommensurate change\npoint (the Affleck-Kennedy-Lieb-Tasaki point, $\\alpha=1/3$). There have been\ntwo different analytical predictions about the static structure factor in the\nneighborhood of this point. By using the S{\\o}rensen-Affleck prescription,\nthese static structure factors are related to the Green functions, and also to\nthe energy gap behaviors. Numerical calculations support one of the\npredictions. Accordingly, the commensurate-incommensurate change is recognized\nas a motion of a pair of poles in the complex plane.",
        "category": "cond-mat"
    },
    {
        "text": "Experimental observation of a large ac-spin Hall effect: In spinelectronics the spin degree of freedom is used to transmit and store\ninformation. Ideally this occurs without net charge currents in order to avoid\nenergy dissipation due to Joule heating. To this end the ability to create pure\nspin currents i.e.without net charge transfer is essential. Spin pumping is the\nmost popular approach to generate pure spin currents in metals, semiconductors,\ngraphene, and even organic materials. When the magnetization vector in a\nferromagnet (FM) - normal metal (NM) junction is excited the spin pumping\neffect leads to the injection of pure spin currents in the normal metal. The\npolarization of this spin current is time dependent and contains a very small\ndc component. The dc-component of the injected spin current has been intensely\nstudied in recent years and has given rise to controversial discussions\nconcerning the magnitude the spin Hall angle which is a material dependent\nmeasure of the efficiency of spin to charge conversion . However in contrast to\nthe rather well understood dc component the two orders of magnitude larger ac\ncomponent has escaped experimental detection so far. Here we show that the\nlarge ac component of the spin currents can be detected very efficiently using\nthe inverse spin Hall effect (ISHE). The observed ac-ISHE voltages are one\norder of magnitude larger than the conventional dc-ISHE measured on the same\ndevice. The spectral shape, angular dependence, power scaling behavior and\nabsolute magnitude of the signals are in line with spin pumping and ISHE\neffects. Our results demonstrate that FM-NM junctions are very efficient\nsources of pure spin currents in the GHz frequency range and we believe that\nour result will stimulate the emerging field of ac spintronics.",
        "category": "cond-mat"
    },
    {
        "text": "Correlation of the angular dependence of spin-transfer torque and giant\n  magnetoresistance in the limit of diffusive transport in spin valves: Angular variation of giant magnetoresistance and spin-transfer torque in\nmetallic spin-valve heterostructures is analyzed theoretically in the limit of\ndiffusive transport. It is shown that the spin-transfer torque in asymmetric\nspin valves can vanish in non-collinear magnetic configurations, and such a\nnon-standard behavior of the torque is generally associated with a\nnon-monotonic angular dependence of the giant magnetoresistance, with a global\nminimum at a non-collinear magnetic configuration.",
        "category": "cond-mat"
    },
    {
        "text": "A new approach to the inverse problem for current mapping in thin-film\n  superconductors: A novel mathematical approach has been developed to complete the inversion of\nthe Biot-Savart law in one- and two-dimensional cases from measurements of the\nperpendicular component of the magnetic field using the well-developed\nMagneto-Optical Imaging technique. Our approach, especially in the 2D case, is\nprovided in great detail to allow a straightforward implementation as opposed\nto those found in the literature. Our new approach also refines our previous\nresults for the 1D case [Johansen et al., Phys. Rev. B 54, 16264 (1996)], and\nstreamlines the method developed by Jooss et al. [Physica C 299, 215 (1998)]\ndeemed as the most accurate if compared to that of Roth et al. [J. Appl. Phys.\n65, 361 (1989)]. We also verify and streamline the iterative technique, which\nwas developed following Laviano et al. [Supercond. Sci. Technol. 16, 71 (2002)]\nto account for in-plane magnetic fields caused by the bending of the applied\nmagnetic field due to the demagnetising effect. After testing on\nmagneto-optical images of a high quality YBa2Cu3O7 superconducting thin film,\nwe show that the procedure employed is effective.",
        "category": "cond-mat"
    },
    {
        "text": "Symmetry breaking orbital anisotropy on detwinned Ba(Fe1-xCox)2As2 above\n  the spin density wave transition: Nematicity, defined as broken rotational symmetry, has recently been observed\nin competing phases proximate to the superconducting phase in the cuprate high\ntemperature superconductors. Similarly, the new iron-based high temperature\nsuperconductors exhibit a tetragonal to orthorhombic structural transition\n(i.e. a broken C4 symmetry) that either precedes or is coincident with a\ncollinear spin density wave (SDW) transition in undoped parent compounds, and\nsuperconductivity arises when both transitions are suppressed via doping.\nEvidence for strong in-plane anisotropy in the SDW state in this family of\ncompounds has been reported by neutron scattering, scanning tunneling\nmicroscopy, and transport measurements. Here we present an angle resolved\nphotoemission spectroscopy study of detwinned single crystals of a\nrepresentative family of electron-doped iron-arsenide superconductors,\nBa(Fe1-xCox)2As2 in the underdoped region. The crystals were detwinned via\napplication of in-plane uniaxial stress, enabling measurements of single domain\nelectronic structure in the orthorhombic state. At low temperatures, our\nresults clearly demonstrate an in-plane electronic anisotropy characterized by\na large energy splitting of two orthogonal bands with dominant dxz and dyz\ncharacter, which is consistent with anisotropy observed by other probes. For\ncompositions x>0, for which the structural transition (TS) precedes the\nmagnetic transition (TSDW), an anisotropic splitting is observed to develop\nabove TSDW, indicating that it is specifically associated with TS. For\nunstressed crystals, the band splitting is observed close to TS, whereas for\nstressed crystals the splitting is observed to considerably higher\ntemperatures, revealing the presence of a surprisingly large in-plane nematic\nsusceptibility in the electronic structure.",
        "category": "cond-mat"
    },
    {
        "text": "Spatial Confinement Affects the Heterogeneity and Interactions Between\n  Shoaling Fish: Living objects are able to consume chemical energy and process information\nindependently from others. However, living objects can coordinate to form\nordered groups such as schools of fish. This work considers these complex\ngroups as living materials and presents imaging-based experiments of laboratory\nschools of fish to understand how this non-equilibrium activity affects the\nmechanical properties of a group. We use spatial confinement to control the\nmotion and structure of fish within quasi-2D shoals of fish. Using image\nanalysis techniques, we make quantitative observations of the structures, their\nspatial heterogeneity, and their temporal fluctuations. Furthermore, we utilize\nMonte Carlo simulations to replicate the experimentally observed area\ndistribution patterns which provide insight into the effective interactions\nbetween fish and confirm the presence of a confinement-based behavioral\npreference transition. In addition, unlike in short-range interacting systems,\nhere structural heterogeneity and dynamic activities are positively correlated\nas a result of complex interplay between spatial arrangement and behavioral\ndynamics in fish collectives.",
        "category": "cond-mat"
    },
    {
        "text": "Paraelectric and ferroelectric order in two-state dipolar fluids: Monte Carlo simulations are used to examine cooperative creation of polar\nstate in fluids of two-state particles with nonzero dipole in the excited\nstate. With lowering temperature such systems undergo a second order transition\nfrom nonpolar to polar, paraelectric phase. The transition is accompanied by a\ndielectric anomaly of polarization susceptibility increasing by three orders of\nmagnitude. The paraelectric phase is then followed by formation of a nematic\nferroelectric which further freezes into an fcc ferroelectric crystal by a\nfirst order transition. A mean-field model of phase transitions is discussed.",
        "category": "cond-mat"
    },
    {
        "text": "^{75}As NMR study of the growth of paramagnetic-metal domains due to\n  electron doping near the superconducting phase in LaFeAsO_{1-x}F_{x}: We studied the electric and magnetic behavior near the phase boundary between\nantiferromagnetic (AF) and superconducting (SC) phases for a prototype of\nhigh-T_c pnictides LaFeAsO_{1-x}F_{x} by using nuclear magnetic resonance, and\nfound that paramagnetic-metal (PM) domains segregate from AF domains. PM\ndomains grow in size with increasing electron doping level and are accompanied\nby the onset of superconductivity, and thus application of pressure or\nincreasing the doping level causes superconductivity. The existence of PM\ndomains cannot be explained by the existing paradigm that focuses only on the\nrelationship between superconductivity and antiferromagnetism. Based on orbital\nfluctuation theory, the existence of PM domains is evidence of the\nferroquadrupole state.",
        "category": "cond-mat"
    },
    {
        "text": "Collective modes in the anisotropic unitary Fermi gas and the inclusion\n  of a backflow term: We study the collective modes of the confined unitary Fermi gas under\nanisotropic harmonic confinement as a function of the number of atoms. We use\nthe equations of extended superfluid hydrodynamics, which take into account a\ndispersive von Weizsacker-like term in the equaton of state. We also discuss\nthe inclusion of a backflow term in the extended superfluid Lagrangian and the\neffects of this anomalous term on sound waves and Beliaev damping of phonons.",
        "category": "cond-mat"
    },
    {
        "text": "Fermionization and Hubbard Models: We introduce a transformation which allows the fermionization of operators of\nany one-dimensional spin-chain. This fermionization procedure is independent of\nany eventual integrable structure and is compatible with it. We illustrate this\nmethod on various integrable and non-integrable chains, and deduce some general\nresults. In particular, we fermionize XXC spin-chains and study their\nsymmetries. Fermionic realizations of certain Lie algebras and superalgebras\nappear naturally as symmetries of some models. We also fermionize recently\nobtained Hubbard models, and obtain for the first time multispecies analogues\nof the Hubbard model, in their fermionic form. We comment on the conflict\nbetween symmetry enhancement and integrability of these models. Finally, the\nfermionic versions of the non integrable spin-1 and spin-3/2 Heisenberg chains\nare obtained.",
        "category": "cond-mat"
    },
    {
        "text": "Role of oxygen-oxygen hopping in the three-band copper-oxide model:\n  quasiparticle weight, metal insulator and magnetic phase boundaries, gap\n  values and optical conductivity: We investigate the effect of oxygen-oxygen hopping on the three-band\ncopper-oxide model relevant to high-$T_c$ cuprates, finding that the physics is\nchanged only slightly as the oxygen-oxygen hopping is varied. The location of\nthe metal-insulator phase boundary in the plane of interaction strength and\ncharge transfer energy shifts by $\\sim 0.5$eV or less along the charge transfer\naxis, the quasiparticle weight has approximately the same magnitude and doping\ndependence and the qualitative characteristics of the electron-doped and\nhole-doped sides of the phase diagram do not change. The results confirm the\nidentification of La$_2$CuO$_4$ as a material with intermediate correlation\nstrength. However, the magnetic phase boundary as well as higher-energy\nfeatures of the optical spectrum are found to depend on the magnitude of the\noxygen-oxygen hopping. We compare our results to previously published one-band\nand three-band model calculations.",
        "category": "cond-mat"
    },
    {
        "text": "Machine Learning Inter-Atomic Potentials Generation Driven by Active\n  Learning: A Case Study for Amorphous and Liquid Hafnium dioxide: We propose a novel active learning scheme for automatically sampling a\nminimum number of uncorrelated configurations for fitting the Gaussian\nApproximation Potential (GAP). Our active learning scheme consists of an\nunsupervised machine learning (ML) scheme coupled to Bayesian optimization\ntechnique that evaluates the GAP model. We apply this scheme to a Hafnium\ndioxide (HfO2) dataset generated from a melt-quench ab initio molecular\ndynamics (AIMD) protocol. Our results show that the active learning scheme,\nwith no prior knowledge of the dataset is able to extract a configuration that\nreaches the required energy fit tolerance. Further, molecular dynamics (MD)\nsimulations performed using this active learned GAP model on 6144-atom systems\nof amorphous and liquid state elucidate the structural properties of HfO2 with\nnear ab initio precision and quench rates (i.e. 1.0 K/ps) not accessible via\nAIMD. The melt and amorphous x-ray structural factors generated from our\nsimulation are in good agreement with experiment. Additionally, the calculated\ndiffusion constants are in good agreement with previous ab initio studies.",
        "category": "cond-mat"
    },
    {
        "text": "First-principles calculation of the thermoelectric figure of merit for\n  [2,2]paracyclophane-based single-molecule junctions: Here we present a theoretical study of the thermoelectric transport through\n{[}2,2{]}para\\-cyclo\\-phane-based single-molecule junctions. Combining\nelectronic and vibrational structures, obtained from density functional theory\n(DFT), with nonequilibrium Green's function techniques, allows us to treat both\nelectronic and phononic transport properties at a first-principles level. For\nthe electronic part, we include an approximate self-energy correction, based on\nthe DFT+$\\Sigma$ approach. This enables us to make a reliable prediction of all\nlinear response transport coefficients entering the thermoelectric figure of\nmerit $ZT$. Paracyclophane derivatives offer a great flexibility in tuning\ntheir chemical properties by attaching different functional groups. We show\nthat, for the specific molecule, the functional groups mainly influence the\nthermopower, allowing to tune its sign and absolute value. We predict that the\nfunctionalization of the bare paracyclophane leads to a largely enhanced\nelectronic contribution $Z_{\\mathrm{el}}T$ to the figure of merit.\nNevertheless, the high phononic contribution to the thermal conductance\nstrongly suppresses $ZT$. Our work demonstrates the importance to include the\nphonon thermal conductance for any realistic estimate of the $ZT$ for\noff-resonant molecular transport junctions. In addition, it shows the\npossibility of a chemical tuning of the thermoelectric properties for a series\nof available molecules, leading to equally performing hole- and\nelectron-conducting junctions based on the same molecular framework.",
        "category": "cond-mat"
    },
    {
        "text": "Origin and magnitude of 'designer' spin-orbit interaction in graphene on\n  semiconducting transition metal dichalcogenides: We use a combination of experimental techniques to demonstrate a general\noccurrence of spin-orbit interaction (SOI) in graphene on transition metal\ndichalcogenide (TMD) substrates. Our measurements indicate that SOI is\nultra-strong and extremely robust, despite it being merely\ninterfacially-induced, with neither graphene nor the TMD substrates changing\ntheir structure. This is found to be the case irrespective of the TMD material\nused, of the transport regime, of the carrier type in the graphene band, and of\nthe thickness of the graphene multilayer. Specifically, we perform weak\nantilocalization measurements as the simplest and most general diagnostic of\nSOI, and show that the spin relaxation time is very short in all cases\nregardless of the elastic scattering time. Such a short spin-relaxation time\nstrongly suggests that the SOI originates from a modification of graphene band\nstructure. We confirmed this expectation by measuring a gate-dependent beating,\nand a corresponding frequency splitting, in the low-field Shubnikov-de Haas\nmagneto-resistance oscillations in high quality bilayer graphene on WSe$_2$.\nThese measurements provide an unambiguous diagnostic of a SOI-induced splitting\nin the electronic band structure, and their analysis allows us to determine the\nSOI coupling constants for the Rashba term and the so-called spin-valley\ncoupling term, i.e., the terms that were recently predicted theoretically for\ninterface-induced SOI in graphene. The magnitude of the SOI splitting is found\nto be on the order of 10 meV, more than 100 times greater than the SOI\nintrinsic to graphene. Both the band character of the interfacially induced\nSOI, as well as its robustness and large magnitude make graphene-on-TMD a\npromising system to realize and explore a variety of spin-dependent transport\nphenomena, such as, in particular, spin-Hall and valley-Hall topological\ninsulating states.",
        "category": "cond-mat"
    },
    {
        "text": "Raman scattering of graphene based systems in high magnetic fields: We review the different results obtained in the last decade in the field of\nRaman scattering of graphene based systems, with an applied magnetic field.\nElectronic properties of graphene based systems with an applied magnetic field\nwill first be described. The phonon response in magnetic field, the\nmagneto-phono resonance, will then be introduced and described in different\nsystems, including graphene, multilayer graphene and bulk graphite. Electronic\nRaman scattering is then be discussed in the context of Landau level\nspectroscopy, of electron phonon interaction and of electron-electron\ninteraction.",
        "category": "cond-mat"
    },
    {
        "text": "Structural and optical properties of high quality zinc-blende/wurtzite\n  GaAs hetero-nanowires: The structural and optical properties of 3 different kinds of GaAs nanowires\nwith 100% zinc-blende structure and with an average of 30% and 70% wurtzite are\npresented. A variety of shorter and longer segments of zinc-blende or wurtzite\ncrystal phases are observed by transmission electron microscopy in the\nnanowires. Sharp photoluminescence lines are observed with emission energies\ntuned from 1.515 eV down to 1.43 eV when the percentage of wurtzite is\nincreased. The downward shift of the emission peaks can be understood by\ncarrier confinement at the interfaces, in quantum wells and in random short\nperiod superlattices existent in these nanowires, assuming a staggered\nband-offset between wurtzite and zinc-blende GaAs. The latter is confirmed also\nby time resolved measurements. The extremely local nature of these optical\ntransitions is evidenced also by cathodoluminescence measurements. Raman\nspectroscopy on single wires shows different strain conditions, depending on\nthe wurtzite content which affects also the band alignments. Finally, the\noccurrence of the two crystallographic phases is discussed in thermodynamic\nterms.",
        "category": "cond-mat"
    },
    {
        "text": "Stationary distributions of propelled particles as a system with\n  quenched disorder: This article is the exploration of the viewpoint within which propelled\nparticles in a steady-state are regarded as a system with quenched disorder.\nThe analogy is exact when the rate of the drift orientation vanishes and the\nlinear potential, representing the drift, becomes part of an external\npotential, resulting in the effective potential $u_{eff}$. The stationary\ndistribution is then calculated as a disorder-averaged quantity by considering\nall contributing drift orientations. To extend this viewpoint to the case when\na drift orientation evolves in time, we reformulate the relevant Fokker-Planck\nequation as a self-consistent relation. One interesting aspect of this\nformulation is that it is represented in terms of the Boltzmann factor\n$e^{-\\beta u_{eff}}$. In the case of a run-and-tumble model, the formulation\nreveals an effective interaction between particles.",
        "category": "cond-mat"
    },
    {
        "text": "A Unified Theory of Consequences of Spontaneous Emission in a $\u039b$\n  System: In a $\\Lambda$ system with two nearly degenerate ground states and one\nexcited state in an atom or quantum dot, spontaneous radiative decay can lead\nto a range of phenomena, including electron-photon entanglement, spontaneously\ngenerated coherence, and two-pathway decay. We show that a treatment of the\nradiative decay as a quantum evolution of a single physical system composed of\na three-level electron subsystem and photons leads to a range of consequences\ndepending on the electron-photon interaction and the measurement. Different\ntreatments of the emitted photon channel the electron-photon system into a\nvariety of final states. The theory is not restricted to the three-level\nsystem.",
        "category": "cond-mat"
    },
    {
        "text": "On superstatistical multiplicative-noise processes: In this manuscript we analyse the long-term probability density function of\nnon-stationary dynamical processes which are enclosed inward the Feller class\nof processes with time varying exponents for multiplicative noise. The update\nin the value of the exponent occurs in the same conditions presented by Beck\nand Cohen for superstatistics. Moreover, we are able to provide a dynamical\nscenario for the emergence of a generalisation of the Weibull distribution\npreviously introduced.",
        "category": "cond-mat"
    },
    {
        "text": "Infrared phonon spectrum of the tetragonal helimagnet\n  Ba$_2$CuGe$_2$O$_7$: The lattice dynamics of Ba$_2$CuGe$_2$O$_7$, a compound which develops\nDzyaloshinsky-Moriya (DM) helical magnetism below $T_N$ = 3.2 K, has been\nstudied by measuring the infrared reflectivity of a single crystal with the\nradiation polarized both in the $ab$ plane and along the $c$ axis of its\ntetragonal cell, from 7 K to 300 K. In this compound, where the unit cell has\nno inversion symmetry, fourteen $E$ phonon modes of the $ab$ plane, out of the\neighteen predicted, and all the ten $B_2$ modes of the $c$ axis, have been\nobserved. They have been assigned to the atomic motions by a comparison with\nshell-model calculations, which provided vibrational frequencies in good\nagreement with the experiment, while most calculated intensities turned to be\nmuch lower than the experimental values. This discrepancy has been tentatively\nexplained by assuming strong electron-phonon interactions, a hypothesis\nsupported by the failure of the $f$- sum rule if restricted to the phonon\nregion. Indeed, we observe a remarkable increase in the oscillator strengths at\n$T$'s low but higher than $T_N$, which suggests that the dielectric constant of\nBa$_2$CuGe$_2$O$_7$ may increase at those temperatures.",
        "category": "cond-mat"
    },
    {
        "text": "Monte Carlo study of the magnetic properties of the 3D Hubbard model: We investigate numerically the magnetic properties of the 3D Isotropic and\nAnisotropic Hubbard model at half-filling. The behavior of the transition\ntemperature as a function of the anisotropic hopping parameter is qualitatively\ndescribed. In the Isotropic model we measure the scaling properties of the\nsusceptibility finding agreement with the magnetic critical exponents of the 3D\nHeisenberg model. We also describe several particularities concerning the\nimplementation of our simulation in a cluster of personal computers.",
        "category": "cond-mat"
    },
    {
        "text": "Nitrogen incorporated Zinc oxide thin film for efficient ethanol\n  detection: Zinc oxide which is a n-type semiconducting metal oxide (SMO) has been a\npromising material for detecting ethanol vapor. However, pure ZnO based ethanol\nsensors often suffer from high working temperature, cross sensitivity towards\nmethanol and poor stability against humidity. Doping ZnO with various metal\nions has been widely explored as a proficient approach to improve its ethanol\nsensing properties, while anionic dopants have been rarely considered. Here in\nwe demonstrate the effect of nitrogen doping on the ethanol sensing\ncharacteristics of ZnO thin films. Nitrogen doped ZnO (N-ZnO) thin films have\nbeen synthesized following sol-gel technique with urea as nitrogen precursor.\nEthanol sensing characteristics of the N-ZnO thin film has been com-pared with\npure ZnO sensor over a wide range of temperature and relative humidity\nconditions. The N-ZnO sensor exhibits significantly large ethanol sensing\nresponse at a lower operating temperature (~99 % at 225 {\\deg}C vs ~81 % at 250\n{\\deg}C for ZnO), faster response time (12 s vs 33 s for ZnO), long term\nstability, improved resilience against humidity and selectivity towards ethanol\nover methanol and acetone. The experimental observations have been supplemented\nby estimating the adsorption energies of ethanol on ZnO and N-ZnO surface using\ndensity functional theory (DFT) calculations. We discuss that the microscopic\norigin of improved ethanol sensing of N-ZnO is related to the facile adsorption\nof ethanol molecules on the oxide surface which is promoted by modification of\nelectronic properties of ZnO by the nitrogen dopant atoms.",
        "category": "cond-mat"
    },
    {
        "text": "Elemental substitution tuned magneto elastoviscous behavior of nanoscale\n  ferrite MFe2O4 M = Mn, Fe, Co, Ni based complex fluids: The present article reports the governing influence of substituting the M2\nsite in nanoscale MFe2O4 spinel ferrites by different magnetic metals\nFe,Mn,Co,Ni on magnetorheological and magneto elastoviscous behaviors of the\ncorresponding magnetorheological fluids MRFs. Different doped MFe2O4\nnanoparticles have been synthesized using the polyol assisted hydrothermal\nmethod. Detailed steady and oscillatory shear rheology have been performed on\nthe MRFs to determine the magneto-viscoelastic responses. The MRFs exhibit\nshear thinning behavior and augmented yield characteristics under influence of\nmagnetic field. The steady state magnetoviscous behaviors are scaled against\nthe governing Mason number and self similar response from all the MRFs have\nbeen noted. The MRFs conform to an extended Bingham plastic model under field\neffect. Transient magnetoviscous responses show distinct hysteresis behaviors\nwhen the MRFs are exposed to time varying magnetic fields. Oscillatory shear\nstudies using frequency and strain amplitude sweeps exhibit predominant solid\nlike behaviors under field environment. However, the relaxation behaviors and\nstrain amplitude sweep tests of the MRFs reveal that while the fluids show\nsolid like behaviors under field effect, they cannot be termed as typical\nelastic fluids. Comparisons show that the MnFe2O4 MRFs have superior yield\nperformance among all. However, in case of dynamic and oscillatory systems,\nCoFe2O4 MRFs show the best performance. The viscoelastic responses of the MRFs\nare noted to correspond to a three element viscoelastic model. The study may\nfind importance in design and development strategies of nano MRFs for different\napplications.",
        "category": "cond-mat"
    },
    {
        "text": "Single-layer $1T'$-MoS$_2$ under electron irradiation from $ab$ $initio$\n  molecular dynamics: Irradiation with high-energy particles has recently emerged as an effective\ntool for tailoring the properties of two-dimensional transition metal\ndichalcogenides. In order to carry out an atomically-precise manipulation of\nthe lattice, a detailed understanding of the beam-induced events occurring at\nthe atomic scale is necessary. Here, we investigate the response of\n$1T'$-MoS$_2$ to the electron irradiation by $ab$ $initio$ molecular dynamics\nmeans. Our simulations suggest that an electron beam with energy smaller than\n75 keV does not result in any knock-on damage. The displacement threshold\nenergies are different for the two nonequivalent sulfur atoms in $1T'$-MoS$_2$\nand strongly depend on whether the top or bottom chalcogen layer is considered.\nAs a result, a careful tuning of the beam energy can promote the formation of\nordered defects in the sample. We further discuss the effect of the electron\nirradiation in the neighborhood of a defective site, the mobility of the sulfur\nvacancies created and their tendency to aggregate. Overall, our work provides\nuseful guidelines for the imaging and the defect engineering of $1T'$-MoS$_2$\nusing electron microscopy.",
        "category": "cond-mat"
    },
    {
        "text": "First-Principles Constitutive Equation for Suspension Rheology: We provide a detailed derivation of a recently developed first-principles\napproach to calculating averages in systems of interacting, spherical Brownian\nparticles under time-dependent flow. Although we restrict ourselves to flows\nwhich are both homogeneous and incompressible, the time-dependence and geometry\n(e.g. shear, extension) are arbitrary. The approximations formulated within\nmode-coupling theory are particularly suited to dense colloidal suspensions and\ncapture the slow relaxation arising from particle interactions and the\nresulting glass transition to an amorphous solid. The delicate interplay\nbetween slow structural relaxation and time-dependent external flow in\ncolloidal suspensions may thus be studied within a fully tensorial theory.",
        "category": "cond-mat"
    },
    {
        "text": "Tensor-entanglement renormalization group approach to topological phases: The tensor-entanglement renormalization group approach is applied to\nHamiltonians that realize a class of topologically ordered states -- string-net\ncondensed states. We analyze phase transitions between phases with and without\nstring-net condensation. These phase transitions change topological order\nwithout changing any symmetries. This demonstrates that the tensor-entanglement\nrenormalization group approach can be used to study the phase diagram of a\nquantum system with topologically ordered phases.",
        "category": "cond-mat"
    },
    {
        "text": "Specific Heat of (Ca1-xSrx)3Ru2O7 Single Crystals: We have measured the specific heat of crystals of (Ca1-xSrx)3Ru2O7 using ac-\nand relaxation-time calorimetry. Special emphasis was placed on the\ncharacterization of the Neel (TN=56 K) and structural (Tc = 48 K) phase\ntransitions in the pure, x=0 material. While the latter is believed to be first\norder, detailed measurements under different experimental conditions suggest\nthat all the latent heat (with L ~ 0.3 R) is being captured in a broadened peak\nin the effective heat capacity. The specific heat has a mean-field-like step at\nTN, but its magntitude (Delta cP ~ R) is too large to be associated with a\nconventional itinerant electron (e.g. spin-density-wave) antiferromagnetic\ntransition, while its entropy is too small to be associated with full ordering\nof localized spins. The TN transition broadens with Sr substitution while its\nmagnitude decreases slowly. On the other hand, the entropy change associated\nwith the Tc transition decreases rapidly with Sr substitution and is not\nobservable for our x=0.58 sample.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of ultraslow hole dynamics in the 3D topological insulator\n  Bi2Se3 coated with a thin MgF2 layer using multiphoton pumped UV-Vis\n  transient absorption spectroscopy: Individual relaxation dynamics of electrons and holes in optically pumped\nsemiconductors is rarely observed due to their overlap. Here we report the\nindividual dynamics of long-lived (~200 mks) holes observed at room temperature\nin a 10 nm thick film of the 3D topological insulator (TI) Bi2Se3 coated with a\n10 nm thick MgF2 layer using transient absorption spectroscopy in the UV-Vis\nregion. The ultraslow hole dynamics was observed by applying multiphoton\nresonant pumping of massless Dirac fermions and bound valence electrons in\nBi2Se3 at a certain wavelength sufficient for their photoemission and\nsubsequent trapping at the Bi2Se3/MgF2 interface. The emerging deficit of\nelectrons in the film makes it impossible for the remaining holes to recombine,\nthus causing their ultraslow dynamics measured at a specific probing\nwavelength. We also found an extremely long rise time (~600 ps) for this\nultraslow optical response, which is due to the large spin-orbit coupling (SOC)\nsplitting at the valence band maximum and the resulting intervalley scattering\nbetween the splitting components. The ultraslow hole dynamics in Bi2Se3 due to\nthe presence of the Bi2Se3/MgF2 interface is nevertheless much faster than the\nknown ultraslow electron dynamics at the Si/SiO2 interface, also induced by\nmultiphoton excitation in Si. The observed dynamics of long-lived holes is\ngradually suppressed with decreasing Bi2Se3 film thickness for the 2D TI Bi2Se3\n(film thickness 5, 4, and 2 nm) due to the loss of resonance conditions for\nmultiphoton photoemission caused by the gap opening at the Dirac surface state\nnodes. This behavior indicates that the dynamics of massive Dirac fermions\npredominantly determines the relaxation of photoexcited carriers for both the\n2D topologically nontrivial and 2D topologically trivial insulator phases.",
        "category": "cond-mat"
    },
    {
        "text": "Numerical studies of the fractional quantum Hall effect in systems with\n  tunable interactions: The discovery of the fractional quantum Hall effect in GaAs-based\nsemiconductor devices has lead to new advances in condensed matter physics, in\nparticular the possibility for exotic, topological phases of matter that\npossess fractional, and even non-Abelian, statistics of quasiparticles. One of\nthe main limitations of the experimental systems based on GaAs has been the\nlack of tunability of the effective interactions between two-dimensional\nelectrons, which made it difficult to stabilize some of the more fragile\nstates, or induce phase transitions in a controlled manner. Here we review the\nrecent studies that have explored the effects of tunability of the interactions\noffered by alternative two-dimensional systems, characterized by non-trivial\nBerry phases and including graphene, bilayer graphene and topological\ninsulators. The tunability in these systems is achieved via external fields\nthat change the mass gap, or by screening via dielectric plate in the vicinity\nof the device. Our study points to a number of different ways to manipulate the\neffective interactions, and engineer phase transitions between quantum Hall\nliquids and compressible states in a controlled manner.",
        "category": "cond-mat"
    },
    {
        "text": "Fourier Transform Scanning Tunneling Spectroscopy: the possibility to\n  obtain constant energy maps and the band dispersion using a local measurement: We present here an overview of the Fourier Transform Scanning Tunneling\nspectroscopy technique (FT-STS). This technique allows one to probe the\nelectronic properties of a two-dimensional system by analyzing the standing\nwaves formed in the vicinity of defects. We review both the experimental and\ntheoretical aspects of this approach, basing our analysis on some of our\nprevious results, as well as on other results described in the literature. We\nexplain how the topology of the constant energy maps can be deduced from the FT\nof dI/dV map images which exhibit standing waves patterns. We show that not\nonly the position of the features observed in the FT maps, but also their shape\ncan be explained using different theoretical models of different levels of\napproximation. Thus, starting with the classical and well known expression of\nthe Lindhard susceptibility which describes the screening of electron in a free\nelectron gas, we show that from the momentum dependence of the susceptibility\nwe can deduce the topology of the constant energy maps in a joint density of\nstates approximation (JDOS). We describe how some of the specific features\npredicted by the JDOS are (or are not) observed experimentally in the FT maps.\nThe role of the phase factors which are neglected in the rough JDOS\napproximation is described using the stationary phase conditions. We present\nalso the technique of the T-matrix approximation, which takes into account\naccurately these phase factors. This technique has been successfully applied to\nnormal metals, as well as to systems with more complicated constant energy\ncontours. We present results recently obtained on graphene systems which\ndemonstrate the power of this technique, and the usefulness of local\nmeasurements for determining the band structure, the map of the Fermi energy\nand the constant-energy maps.",
        "category": "cond-mat"
    },
    {
        "text": "Electronic structure and magnetic interactions in LiV2O4: We present results of all-electron electronic structure calculations for the\nrecently discovered d electron heavy fermion compound LiV_2O_4. The augmented\nspherical wave calculations are based on density functional theory within the\nlocal density approximation. The electronic properties near the Fermi energy\noriginate almost exclusively from V 3d t_{2g} states, which fall into two\nequally occupied subbands: While sigma-type metal-metal bonding leads to rather\nbroad bands, small pi-type p-d overlap causes a narrow peak at E_F. Without the\ngeometric frustration inherent in the crystal structure, spin-polarized\ncalculations reveal an antiferromagnetic ground state and ferromagnetic order\nat slightly higher energy. Since direct d-d exchange interaction plays only a\nminor role, ordering of the localized vanadium moments can be attributed\nexclusively to a rather weak superexchange interaction. With the magnetic order\nsuppressed by the geometric frustration, the remaining spin fluctuations\nsuggest an explanation of the low temperature behaviour of the specific heat.",
        "category": "cond-mat"
    },
    {
        "text": "Effective thermodynamics for a marginal observer: Thermodynamics is usually formulated on the presumption that the observer has\ncomplete information about the system he/she deals with: no parasitic current,\nexact evaluation of the forces that drive the system. For example, the\nacclaimed Fluctuation Relation (FR), relating the probability of time-forward\nand time-reversed trajectories, assumes that the measurable transitions suffice\nto characterize the process as Markovian (in our case, a continuous-time jump\nprocess). However, most often the observer only measures a marginal current. We\nshow that he/she will nonetheless produce an effective description that does\nnot dispense with the fundamentals of thermodynamics, including the FR and the\n2nd law. Our results stand on the mathematical construction of a hidden time\nreversal of the dynamics, and on the physical requirement that the observed\ncurrent only accounts for a single transition in the configuration space of the\nsystem. We employ a simple abstract example to illustrate our results and to\ndiscuss the feasibility of generalizations.",
        "category": "cond-mat"
    },
    {
        "text": "Spin-asymmetric Josephson effect: The Josephson effect is a manifestation of the macroscopic phase coherence of\nsuperconductors and superfluids. We propose that with ultracold Fermi gases one\ncan realise a spin-asymmetric Josephson effect in which the two spin components\nof a Cooper pair are driven asymmetrically - corresponding to driving a\nJosephson junction of two superconductors with different voltages V_\\uparrow\nand V_\\downarrow for spin up and down electrons, respectively. We predict that\nthe spin up and down components oscillate at the same frequency but with\ndifferent amplitudes. Our results reveal that the standard description of the\nJosephson effect in terms of bosonic pair tunnelling is insufficient. We\nprovide an intuitive interpretation of the Josephson effect as interference in\nRabi oscillations of pairs and single particles, the latter causing the\nasymmetry.",
        "category": "cond-mat"
    },
    {
        "text": "Dynamics of two trapped Brownian particles: shear-induced\n  cross-correlations: The dynamics of two Brownian particles trapped by two neighboring harmonic\npotentials in a linear shear flow is investigated. The positional correlation\nfunctions in this system are calculated analytically and analyzed as a function\nof the shear rate and the trap distance. Shear-induced cross-correlations\nbetween particle fluctuations along orthogonal directions in the shear plane\nare found. They are linear in the shear rate, asymmetric in time, and occur for\none particle as well as between both particles. Moreover, the shear rate enters\nas a quadratic correction to the well-known correlations of random\ndisplacements along parallel spatial directions. The correlation functions\ndepend on the orientation of the connection vector between the potential minima\nwith respect to the flow direction. As a consequence, the inter-particle\ncross-correlations between orthogonal fluctuations can have zero, one or two\nlocal extrema as a function of time. Possible experiments for detecting these\npredicted correlations are described.",
        "category": "cond-mat"
    },
    {
        "text": "Accurate Prediction of Bonding Properties by A Machine Learning-based\n  Model using Isolated States Before Bonding: Given the strong dependence of material structure and properties on the\nlength and strength of constituent bonds and the fact that surface adsorption\nand chemical reactions are initiated by the formation of bonds between two\nsystems, bonding parameters are of key importance for material design and\nindustrial processes. In this study, a machine learning (ML)-based model is\nused to accurately predict bonding properties from information pertaining to\nisolated systems before bonding. This model employs the density of states (DOS)\nbefore bond formation as the ML descriptor and accurately predicts binding\nenergy, bond distance, covalent electron amount, and Fermi energy even when\nonly 20% of the whole dataset is used for training. The results show that the\nDOS of isolated systems before bonding is a powerful descriptor for the\naccurate prediction of bonding and adsorption properties.",
        "category": "cond-mat"
    },
    {
        "text": "Dielectric and structural studies of ferroelectric phase evolution in\n  dipole pair substituted barium titanate ceramics: Ba{[Gax,Tax]Ti(1-2x)}O3 ceramics with x equal to 0, 0.0025, 0.005, 0.01,\n0.025 and 0.05 have been prepared by conventional solid-state reaction.\nStructural and dielectric characterization have been performed to investigate\nthe effect of dipole-pair substitution concentration on the macroscopic\ndielectric properties. Ba{[Gax,Tax]Ti(1-2x)}O3 evolves from a classic\nferroelectric to a diffuse phase transition (DPT) as x increases.\nBa{[Gax,Tax]Ti(1-2x)}O3 for x > or = 0.01 possesses diffuseness parameters\ncomparable to Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and recently reported\n(Ba0.97Pr0.03)(Ti0.9425Ce0.05)O3 (BPTC), yet it lacks the frequency and\ntemperature dependence of Tm necessary to be a strictly defined relaxor\nferroelectric. Additionally, Ba{[Ga0.05,Ta0.05]Ti0.9}O3 possesses a relative\npermittivity, {\\epsilon}r, of 700+/-16% and dissipation factor less than 0.05\nat 10 kHz within the temperature range [-75{\\deg}C, 120{\\deg}C]. In comparison\nto BaTiO3, Ba{[Gax,Tax]Ti(1-2x)}O3 possesses enhanced electrical resistivity at\nand above room temperature. In-situ XRD, including Rietveld refinement, have\nbeen performed to determine the lattice parameter, coefficient of thermal\nexpansion and phase transition temperature (Tc) of each composition within the\ntemperature range [RT, 1000{\\deg}C], thus linking the dielectric properties\nwith the materials structure. These studies have been corroborated by\ntemperature dependent Raman spectroscopy to compare the Tc determined by\nelectrical and structural characterization. The properties of\nBa{[Gax,Tax]Ti(1-2x)}O3 are discussed in context with available models that\ndescribe donor and acceptor dopants spatially separated in the parent matrix,\ninter-relating lattice parameter, Curie temperature, and other material\nproperties",
        "category": "cond-mat"
    },
    {
        "text": "Optically driven rotation of exciton-polariton condensates: The rotational response of quantum condensed fluids is strikingly distinct\nfrom rotating classical fluids, especially notable for the excitation and\nordering of quantized vortex ensembles. Although widely studied in conservative\nsystems, the dynamics of rotating open-dissipative superfluids such as\nexciton-polariton condensates remain largely unexplored, as it requires\nhigh-frequency rotation whilst avoiding resonantly driving the condensate. We\ncreate a rotating polariton condensate at GHz frequencies by off-resonantly\npumping with a rotating optical stirrer composed of the time-dependent\ninterference of two frequency-offset, structured laser modes. Acquisition of\nangular momentum exceeding the critical $1\\hbar$/particle is directly measured,\naccompanied by the deterministic nucleation and capture of quantized vortices\nwith a handedness controlled by the pump rotation direction. The demonstration\nof controlled optical rotation of a spontaneously formed polariton condensate\nenables new opportunities for the study of open-dissipative superfluidity,\nordering of non-Hermitian quantized vortex matter, and topological states in a\nhighly non-linear, photonic platform.",
        "category": "cond-mat"
    },
    {
        "text": "Strongly Correlated Chern Insulators in Magic-Angle Twisted Bilayer\n  Graphene: Interactions among electrons and the topology of their energy bands can\ncreate novel quantum phases of matter. Most topological electronic phases\nappear in systems with weak electron-electron interactions. The instances where\ntopological phases emerge only as a result of strong interactions are rare, and\nmostly limited to those realized in the presence of intense magnetic fields.\nThe discovery of flat electronic bands with topological character in\nmagic-angle twisted bilayer graphene (MATBG) has created a unique opportunity\nto search for new strongly correlated topological phases. Here we introduce a\nnovel local spectroscopic technique using a scanning tunneling microscope (STM)\nto detect a sequence of topological insulators in MATBG with Chern numbers C =\n$\\pm$ 1, $\\pm$ 2, $\\pm$ 3, which form near $\\nu$ = $\\pm$ 3, $\\pm$ 2, $\\pm$ 1\nelectrons per moir\\'e unit cell respectively, and are stabilized by the\napplication of modest magnetic fields. One of the phases detected here (C = +1)\nhas been previously observed when the sublattice symmetry of MATBG was\nintentionally broken by hexagonal boron nitride (hBN) substrates, with\ninteractions playing a secondary role. We demonstrate that strong\nelectron-electron interactions alone can produce not only the previously\nobserved phase, but also new and unexpected Chern insulating phases in MATBG.\nThe full sequence of phases we observed can be understood by postulating that\nstrong correlations favor breaking time-reversal symmetry to form Chern\ninsulators that are stabilized by weak magnetic fields. Our findings illustrate\nthat many-body correlations can create topological phases in moir\\'e systems\nbeyond those anticipated from weakly interacting models.",
        "category": "cond-mat"
    },
    {
        "text": "Phase transition of Two-timescale Two-temperature Spin-lattice Gas Model: We study phase transition of a nonequilibrium statistical-mechanical model,\nin which two degrees of freedom with different time scales separated from each\nother touch to their own heat bath. A general condition for finding anomalous\nnegative latent heat recently discovered is derived a from thermodynamic\nargument. As a specific example, phase diagram of a spin-lattice gas model is\nstudied based on a mean-field analysis with replica method. While\nconfigurational variables are spin and particle in this model, it is found that\nthe negative latent heat appears in a parameter region of the model,\nirrespective of the order of their time scale. Qualitative differences in the\nphase diagram are also discussed.",
        "category": "cond-mat"
    },
    {
        "text": "Adiabatic magnon spectra with and without constraining field: Benchmark\n  against an exact magnon spectrum: The spectrum of magnon excitations in magnetic materials can be obtained\nexactly from the transverse dynamic magnetic susceptibility, which is however\nin practice numerically expensive. Many ab initio approaches therefore consider\ninstead the adiabatic magnon spectrum, which assumes a separation of time\nscales of magnons and electronic excitations. There exist two alternative\nimplementations for adiabatic magnon spectra: one based on the magnetic force\ntheorem (MFT) and the other with a constraining field that enforces static\nnon-collinear spin configurations. We benchmark both implementations against\nthe exact magnon spectrum of an exactly solvable mean-field model. While both\nadiabatic methods are equally valid in the low magnon energy and strong Stoner\ncoupling limits, we find that the constraining field method performs better\nthan the MFT in both the cases of strong Stoner coupling and high magnon\nenergies,while the MFT performs better for combined weak coupling and low\nmagnon energies.",
        "category": "cond-mat"
    },
    {
        "text": "Observation of the In-plane Anomalous Hall Effect induced by Octupole in\n  Magnetization Space: The Anomalous Hall Effect (AHE) manifests as a transverse voltage\nproportional to magnetization in ferromagnetic materials under the application\nof a charge current, being an indispensable tool for probing magnetism,\nespecially in nanoscale devices. However, the AHE primarily sensitizes to\nout-of-plane magnetization, thereby hindering its capacity to discern the\nin-plane magnetization, a characteristic prevalent in ferromagnetic films. Here\nwe challenge this conventional understanding by demonstrating the in-plane\nmagnetization-induced AHE in iron and nickel, two ubiquitous ferromagnets. This\nobservation of the in-plane AHE is remarkable as it contradicts existing\ntheories that forbid such phenomena in cubic crystal systems. We trace the\norigin of this unanticipated phenomenon to a hitherto unconsidered octupole of\nthe anomalous Hall conductivity in the magnetization space, a mechanism we\npropose could enable the detection of in-plane AHE in a wide range of\nferromagnetic materials. This work realizes the in-plane AHE in common\nferromagnets by exploiting the anomalous Hall conductivity octupole, revealing\na new physical origin of the AHE and promising to revolutionize the design of\nmagnetic devices and sensors.",
        "category": "cond-mat"
    },
    {
        "text": "Solving the Poisson-Boltzmann Equation to Obtain Interaction Energies\n  Between Confined, Like-charged Cylinders: We numerically solve the non-linear Poisson-Boltzmann equation for two\ncylinders confined by two parallel charged plates. The repulsive electrical\ndouble layer component of the cylinder pair potential is substantially reduced\nby confinement between like-charged plates. While the effective cylinder\nsurface charge is increased by the confinement, the effective interaction\nscreening length is reduced, this effect being dominant so that the repulsive\nconfined cylinder-cylinder interaction potential is reduced.",
        "category": "cond-mat"
    },
    {
        "text": "Time irreversibility from symplectic non-squeezing: The issue of how time reversible microscopic dynamics gives rise to\nmacroscopic irreversible processes has been a recurrent issue in Physics since\nthe time of Boltzmann whose ideas shaped, and essentially resolved, such an\napparent contradiction. Following Boltzmann's spirit and ideas, but employing\nGibbs's approach, we advance the view that macroscopic irreversibility of\nHamiltonian systems of many degrees of freedom can be also seen as a result of\nthe symplectic non-squeezing theorem.",
        "category": "cond-mat"
    },
    {
        "text": "Analysis of Magnetization Loss on a Twisted Superconducting Strip in a\n  Constantly Ramped Magnetic Field: Magnetization loss on a twisted superconducting (SC) tape in a ramped\nmagnetic field is theoretically investigated through the use of a power law for\nthe electric field--current density characteristics and a sheet current\napproximation. First, the Maxwell equation in a helicoidal coordinate system is\nderived to model a twisted SC tape, taking account of the response to the\nperpendicular field component in the steady state. We show that a loosely\ntwisted tape can be viewed as the sum of a portion of tilted flat tapes of\ninfinite length by examining the perpendicular field distribution on a twisted\ntape. The analytic formulae for both magnetization and loss power in the tilted\nflat tape approximation are verified based on the analytic solution of the\nreduced Maxwell equation in the loosely twisted tape limit of $L_{\\rm\np}\\rightarrow \\infty$ with the twist pitch length $L_{\\rm p}$. These analytic\nformulae show that both magnetization and loss power decrease by a factor of\n$B(1+1/2n,1/2)/\\pi$ (where $B$ is the beta function) for an arbitrary power of\nSC nonlinear resistivity $n$, compared with those in a flat tape of infinite\nlength. Finally, the effect of the field-angle dependence of the critical\ncurrent density $J_{\\rm c}$ on the loss power is investigated, and we\ndemonstrate that it is possible to obtain an approximate estimate of the loss\npower value via $J_{\\rm c}$ in an applied magnetic field perpendicular to the\ntape surface (i.e., parallel to the $c$ axis).",
        "category": "cond-mat"
    },
    {
        "text": "Controlling the dynamic range of a Josephson parametric amplifier: One of the central challenges in the development of parametric amplifiers is\nthe control of the dynamic range relative to its gain and bandwidth, which\ntypically limits quantum limited amplification to signals which contain only a\nfew photons per inverse bandwidth. Here, we discuss the control of the dynamic\nrange of Josephson parametric amplifiers by using Josephson junction arrays. We\ndiscuss gain, bandwidth, noise, and dynamic range properties of both a\ntransmission line and a lumped element based parametric amplifier. Based on\nthese investigations we derive useful design criteria, which may find broad\napplication in the development of practical parametric amplifiers.",
        "category": "cond-mat"
    },
    {
        "text": "Prediction of High Transition Temperatures in Ceramic Superconductors: The prediction of transition temperatures can be regarded in several ways,\neither as an exacting test of theory, or as a tool for identifying theoretical\nrules for defining new homology models. Popular \"first principle\" methods for\npredicting transition temperatures in conventional crystalline superconductors\nhave failed for cuprate HTSC, as have parameterized models based on CuO2 planes\n(with or without apical oxygen). Following a path suggested by Bayesian\nprobability, we find that the glassy, self-organized dopant network percolative\nmodel is so successful that it defines a new homology class appropriate to\nceramic superconductors. The reasons for this success are discussed, and a\ncritical comparison is made with previous theories. The predictions are\nsuccessful for all ceramics, including new non-cuprates based on FeAs in place\nof CuO2.",
        "category": "cond-mat"
    },
    {
        "text": "Origin of giant magnetoresistance in layered nodal-line semimetal\n  TaNiTe5 nanoflakes: Layered transition metal chalcogenides have stimulated a wide research\ninterest due to its many exotic physical properties. In this paper, we studied\nthe magnetotransport properties of the exfoliated TaNiTe5, a recently\ndiscovered Dirac nodal-line semimetal. A giant positive magnetoresistance (MR)\nis observed when the current is parallel to the crystallographic c axis, while\nit is strongly diminished when the current flows along the a axis. The observed\ngiant MR is gradually suppressed either on reducing the thickness of nanoflake\nor on increasing temperature. By performing MR measurement in tilted magnetic\nfields, the interlayer coupling is found to be weakened both by reducing the\nthickness and by increasing temperature. We propose a mechanism of\nelectron-electron interaction-assisted interlayer transport as a origin of the\ngiant MR. The mechanism is likely to provide a explanation for the giant MR in\nother layered materials.",
        "category": "cond-mat"
    },
    {
        "text": "Quantum criticality of magnetic catalysis in two-dimensional correlated\n  Dirac fermions: We study quantum criticality of the magnetic field induced charge density\nwave (CDW) order in correlated spinless Dirac fermions on the $\\pi$-flux square\nlattice at zero temperature as a prototypical example of the magnetic\ncatalysis, by using the infinite density matrix renormalization group. It is\nfound that the CDW order parameter $M(B)$ exhibits an anomalous magnetic field\n$(B)$ scaling behavior characteristic of the $(2+1)$-dimensional chiral Ising\nuniversality class near the quantum critical point, which leads to a strong\nenhancement of $M(B)$ compared with a mean field result. We also establish a\nglobal phase diagram in the interaction-magnetic field plane for the fermionic\nquantum criticality.",
        "category": "cond-mat"
    },
    {
        "text": "Composite Fermions and the Energy Gap in the Fractional Quantum Hall\n  Effect: The energy gaps for the fractional quantum Hall effect at filling fractions\n1/3, 1/5, and 1/7 have been calculated by variational Monte Carlo using Jain's\ncomposite fermion wave functions before and after projection onto the lowest\nLandau level. Before projection there is a contribution to the energy gaps from\nthe first excited Landau level. After projection this contribution vanishes,\nthe quasielectron charge becomes more localized, and the Coulomb energy\ncontribution increases. The projected gaps agree well with previous\ncalculations, lending support to the composite fermion theory.",
        "category": "cond-mat"
    },
    {
        "text": "Diluted antiferromagnets in a field seem to be in a different\n  universality class than the random-field Ising model: We perform large-scale Monte Carlo simulations using the Machta-Newman-Chayes\nalgorithms to study the critical behavior of both the diluted antiferromagnet\nin a field with 30% dilution and the random-field Ising model with Gaussian\nrandom fields for different field strengths. Analytical calculations by Cardy\n[Phys. Rev. B 29, 505 (1984)] predict that both models map onto each other and\nshare the same universality class in the limit of vanishing fields. However, a\ndetailed finite-size scaling analysis of both the Binder cumulant and the\ntwo-point finite-size correlation length suggests that even in the limit of\nsmall fields, where the mapping is expected to work, both models are not in the\nsame universality class. Therefore, care should be taken when interpreting\n(experimental) data for diluted antiferromagnets in a field using the\nrandom-field Ising model. Based on our numerical data, we present analytical\nexpressions for the phase boundaries of both models.",
        "category": "cond-mat"
    },
    {
        "text": "Nonlocal elasticity near jamming: We demonstrate that the elasticity of jammed solids is nonlocal. By forcing\nfrictionless soft sphere packings at varying wavelength, we directly access\ntheir transverse and longitudinal compliances without resorting to curve\nfitting. The observed wavelength dependence of the compliances is incompatible\nwith classical (local) elasticity, and hence quantifies the amplitude of\nnonlocal effects. Three distinct length scales, two of which diverge, control\nthe amplitude of both nonlocal effects and fluctuations about the mean\nresponse. Our results identify new, more accurate constitutive relations for\nweakly jammed solids, including emulsions, foams, and granulates.",
        "category": "cond-mat"
    },
    {
        "text": "The magnetic field induced phase separation in a model of a\n  superconductor with local electron pairing: We have studied the extended Hubbard model with pair hopping in the atomic\nlimit for arbitrary electron density and chemical potential and focus on\nparamagnetic effects of the external magnetic field. The Hamiltonian considered\nconsists of (i) the effective on-site interaction U and (ii) the intersite\ncharge exchange interactions I, determining the hopping of electron pairs\nbetween nearest-neighbour sites. The phase diagrams and thermodynamic\nproperties of this model have been determined within the variational approach\n(VA), which treats the on-site interaction term exactly and the intersite\ninteractions within the mean-field approximation. Our investigation of the\ngeneral case shows that the system can exhibit not only the homogeneous phases:\nsuperconducting (SS) and nonordered (NO), but also the phase separated states\n(PS: SS-NO). Depending on the values of interaction parameters, the PS state\ncan occur in higher fields than the SS phase (field-induced PS). Some ground\nstate results beyond the VA are also presented.",
        "category": "cond-mat"
    },
    {
        "text": "The effects of interstitials clustering on the configurational entropy\n  of bcc solid solutions: This work presents a simple model for describing the interstitials behavior\nin solid solutions enlarging the current random interstitial atoms paradigm. A\ngeneral and parameter-free analytical expression to compute the configurational\nentropy, valid for any tetrahedral or octahedral interstitial solutions and\nsuitable for the treatment of interstitials clustering, is deduced for that\npurpose. The effect of interstitials clustering on the configurational entropy\nis shown by applying the methodology to the Nb-H and bcc Zr-H solid solutions.\nThe model for Nb-H presented in this work, based on the existence of H pairs in\nthe \\alpha phase and double pairs in the \\alpha 'phase, provides the basis to\nexplain the unsolved controversies in this system. The unusual shape of the\npartial configurational entropy measured in bcc Zr-H can be accurately\ndescribed if a small amount of H clusters are included in the solution.",
        "category": "cond-mat"
    },
    {
        "text": "Self-organised quantum dots in marginally twisted MoSe$_2$/WSe$_2$ and\n  MoS$_2$/WS$_2$ bilayers: Moir\\'e superlattices in twistronic heterostructures are a powerful tool for\nmaterials engineering. In marginally twisted (small misalignment angle,\n$\\theta$) bilayers of nearly lattice-matched two-dimensional (2D) crystals\nmoir\\'e patterns take the form of domains of commensurate stacking, separated\nby a network of domain walls (NoDW) with strain hot spots at the NoDW nodes.\nHere, we show that, for type-II transition metal dichalcogenide bilayers\nMoX$_2$/WX$_2$ (X=S, Se), the hydrostatic strain component in these hot spots\ncreates quantum dots for electrons and holes. We investigate the electron/hole\nstates bound by such objects, discussing their manifestations via the\nintralayer intraband infrared transitions. The electron/hole confinement, which\nis strongest for $\\theta<0.5^{\\circ}$, leads to a red-shift of their\nrecombination line producing single photon emitters (SPE) broadly tuneable\naround 1\\,eV by misalignment angle. These self-organised dots can form in\nbilayers with both aligned and inverted MoX$_2$ and WX$_2$ unit cells, emitting\nphotons with different polarizations. We also find that the hot spots of strain\nreduce the intralayer MoX$_2$ A-exciton energy, enabling selective population\nof the quantum dot states.",
        "category": "cond-mat"
    },
    {
        "text": "Magnetotransport Properties of Antiferromagnetic YBa_2Cu_3O_6.25 Single\n  Crystals: In-plane and out-of-plane magnetoresistivities (MR) of antiferromagnetic\nYBa_2Cu_3O_6.25 single crystals were measured in magnetic fields H applied\nalong the (ab) plane. In-plane MR is a superposition of two components: The\nfirst component is strongly in-plane anisotropic, changing sign from negative\nwhen H is parallel to the electrical current I to positive when H is\nperpendicular to I. The second component is positive, quadratic in H, and\nisotropic in the (ab)-plane. The out-of-plane MR displays a fourfold symmetry\nupon in-plane rotation of the magnetic field, with maxima along the easy axes\nof antiferromagnetic spin ordering and minima along unfavorable directions of\nspin orientation (45 degrees from the Cu-O-Cu bonds).",
        "category": "cond-mat"
    },
    {
        "text": "Charge renormalization and other exact coupling corrections in the\n  dipolar effective interaction in an electrolyte near a dielectric wall: The aim of the paper is to study the renormalizations of the charge and of\nthe screening length that appear in the large-distance behavior of the\neffective pairwise interaction between two charges in a dilute electrolyte\nsolution, both along a dielectric wall and in the bulk. The electrolyte is\ndescribed by the primitive model in the framework of classical statistical\nmechanics and the electrostatic response of the wall is characterized by its\ndielectric constant.",
        "category": "cond-mat"
    },
    {
        "text": "Large area photoelectrodes based on hybrids of CNT fibres and ALD grown\n  TiO2: Hybridisation is a powerful strategy towards the next generation of\nmultifunctional materials for environmental and sustainable energy\napplications. Here, we report a new inorganic nanocarbon hybrid material\nprepared with atomically controlled deposition of a monocrystalline TiO2 layer\nthat conformally coats a macroscopic carbon nanotube (CNT) fiber. Through X-ray\ndiffraction, Raman spectroscopy and photoemission spectroscopy we detect the\nformation of a covalent Ti-O-C bond at the TiO2/CNT interface and a residual\nstrain of approximately 0.7-2 \\%, which is tensile in TiO2 and compressive in\nthe CNT. It arises after deposition of the amorphous oxide onto the CNT surface\npreviously functionalized by the oxygen plasma used in ALD. These features are\nobserved in samples of different TiO2 thickness, in the range from 10 to 80 nm.\nUltraviolet photoemission spectroscopy on a 20 nm-thick TiO2 coated sample\ngives a work function of 4.27 eV, between that of TiO2 (4.23 eV) and the CNT\nfiber (4.41 eV), and the presence of new interband gap states that shift the\nvalence band maximum to 1.05 eV below the Fermi level. Photoelectrochemical\nmeasurements demonstrate electron transfer from TiO2 to the CNT fiber network\nunder UV irradiation. Electrochemical impedance spectroscopy measurements\nreveal a low resistance for charge transfer and transport, as well as a large\ncapacitance. Our results point to the fact that these hybrids, in which each\nphase has nanometric thickness and the current collector is integrated into the\nmaterial, are very different from conventional electrodes and can provide a\nnumber of superior properties.",
        "category": "cond-mat"
    }
]