CMP Journal 2026-09-22
Statistics
Nature Materials: 1
Nature Reviews Physics: 1
arXiv: 144
Nature Materials
Reconfigurable non-Abelian braiding of nematic bits
Original Paper | Colloids | 2026-09-21 20:00 EDT
Zihan Lei, Xinda Zheng, Jing Zhang, Wentao Tang, Kun Tian, Ganlin Song, Zhawure Asilehan, Zijun Chen, Fernando Vergara, Yu Guan, Rui Zhang, Jinghua Jiang, Chenhui Peng
Non-Abelian braiding offers a route to information processing that is robust against local perturbations, yet its programmable realization in real space remains challenging. Here we present a room-temperature soft-matter platform for reconfigurable non-Abelian braiding based on the light-driven transformations of disclination lines in a nematic liquid crystal. By photonically manipulating the entangled colloids, we weave the lines into chiral double-helix entanglements and encode their topological states as nematic bits. We implement a complete set of braid operations and demonstrate their non-commutativity in three-line networks, a defining signature of non-Abelian behaviour. Repositioning colloidal gates enables in situ reprogramming, whereas the method extends to multiline architectures. Building on the scalability of this approach, we establish a predictive inverse-design framework that algebraically compiles target topological transformations into prescribed spatial routing and layer-by-layer phase corrections. These results establish a programmable classical platform for robust topological transformations and connect soft-matter physics with topological information processing.
Colloids, Liquid crystals, Topological defects
Nature Reviews Physics
Optical information security
Review Paper | Fibre optics and optical communications | 2026-09-21 20:00 EDT
Hongtao Wang
(王洪涛), Haoran Zhang, Xiaoyan Zhou, Chi Li
(李驰), Hao Wang
(王浩), Haoran Ren, Etienne Brasselet, Zhaogang Dong, Andrew Forbes, Weibo Gao, Joel K. W. Yang
Advances in quantum computing threaten the cryptographic stack by undermining widely deployed public-key primitives and tightening security margins for symmetric encryption, thus creating a long-term confidentiality risk. Photonics offers a practical mitigation option as light offers multiple, independently addressable degrees of freedom (that is, polarization, phase, orbital angular momentum, wavelength and time) for high-dimensional encoding; propagation and interference realize intrinsic, massively parallel linear operations with faster processing time than electronics; and hardware spans free-space links to energy-efficient integrated chips. This Review assesses optical information security through the confidentiality, integrity, availability and authenticity (CIA+E) lens across a layered framework, that is, source, channel, encoding/modulation, optical processing, detection, protocol/system and application. We compare classical, quantum and hybrid post-quantum schemes; survey structured light and holographic encryption, high-dimensional multiplexing and photonic physical unclonable function; and examine artificial intelligence-assisted attack and defence. We sketch a pathway towards scalable, robust and energy-efficient secure photonic systems for the post-quantum era.
Fibre optics and optical communications, Nanophotonics and plasmonics, Quantum optics
arXiv
Efficient spectral Galerkin framework for nonlinear transient heat transfer in finite domains
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Théo Andrieux, Andreas Ntinos, Manas V. Upadhyay
Accurately modelling the temporal evolution of heterogeneous temperature fields requires resolving strong nonlinearities in the heat equation arising from temperature-dependent thermophysical properties, latent heats of transformation and any local heat sources/sinks. In this work, we present a spectral Galerkin (SG) framework to solve the fully nonlinear transient heat equation in finite domains to attain the accuracy of high-fidelity finite element (FE) simulations at considerably lower computational cost. The heat equation is reformulated into a linear reference problem with constant thermophysical properties and residual forcing terms. Solving the reference problem provides a complete three-dimensional orthonormal trigonometric basis, whose Galerkin projection reduces the heat equation to a set of modal ordinary differential equations (ODEs) in time; the reference operator is diagonal in the modal basis, and results in independent modal updates for a fixed nonlinear forcing. These ODEs can be integrated using exponential time differencing and iteratively corrected for nonlinearities. The SG method eliminates the global solve required by FE methods, and its use of structured grids allows efficient GPU parallelization. Applied to rapid laser-metal interactions, the SG solver reproduces high-fidelity FE temperature fields with less than 1% relative error while achieving 227-fold faster GPU runtimes. Applied to a part-scale laser scanning study [Ramani et al., Additive Manufacturing 52 (2022) 102643], the method shows that accounting for evaporation and latent heat more than halves their proposed processing metric. The source code of the SG heat solver and some worked examples are available at this https URL under the Apache 2.0 license.
Materials Science (cond-mat.mtrl-sci)
preprint, 30 pages, 1 algorithm, 1 link to source code, 15 figures, 3 tables
Predicting energy and structural response to force correction in molecular dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Peng Kang, Da Wan, Shulin Bai, Pengfei Zhang, Peng Wang, Chenglong Wen, Zhen Li, Yu Liu, Lei Zheng, Li-Dong Zhao
We predict how force correction changes energy exchange and structural statistics by measuring leading response coefficients on shared reference trajectories. Residual power and the displacement virial distinguish the transfer of energy from the change in restoring forces, including intermittent reference updates. Independent simulations then test the predicted kinetic and configurational shifts. A matched-timetable experiment shows that reference timing affects heating through its coupling to the evolving state. In an anharmonic chain, the displacement virial predicts a structural shift missed by a power-only description. Local force constants in silicon predict a complementary directional tradeoff: scalar calibration repairs optical motion while degrading an already accurate low-frequency direction. Full nonlinear trajectories confirm this tradeoff and distinguish the benefits of static curvature correction and repeated reference impulses. Independent finite-temperature integrals in orthorhombic tin selenide (SnSe) support the configurational-response direction predicted from separate reference calculations. These results provide a physical basis for choosing how reference information enters molecular dynamics. The framework assesses force correction through its effect on atomic motion and statistical observables, beyond the accuracy of individual force evaluations.
Materials Science (cond-mat.mtrl-sci)
18 pages, 3 figures
Testing Two-State Access in Brain and Language Model: Human EEG Reproduction, Simulation Audit, and a Proposed Model Assay
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
Brains and the hardware of artificial neural networks are both organized ordinary matter, and whether an artificial system’s organization can support consciousness remains open. This paper examines one proposed mechanism, access to a capacity-limited global workspace, through one prediction of the global neuronal workspace theory: near threshold, the single-trial response distribution is a mixture of two states rather than a continuum. Two completed analyses are reported. First, the published competing-model test of that prediction is reproduced from the authors’ code on the open EEG data of twenty participants. In the active session the two-state model’s protected exceedance probability first exceeds 0.95 at the same 315 ms window, with a modest predictive advantage of about 0.003 nat per trial and optimizer-sensitive interval edges; in the passive session, an additional analysis, a graded comparator ranks highest without an across-window decision. Second, a held-out family comparison proposed for transferring the test to language-model representations is calibrated in simulation at one layer: it made no false two-state call in 12,000 datasets under twelve graded nulls, but its concept-cluster interval under-covered in six settings, down to 0.22, so a replacement interval must be validated before any confirmatory use. The proposed model study, with a natural-text evidence dose, a target bridge and a state-conditional causal test, is specified but not run. No claim about experience is made.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Neurons and Cognition (q-bio.NC)
32 pages, 2 figures, 3 tables. Data and code: this https URL
Towards the spin-glass transition in finite dimensions via blue percolation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
We prove blue percolation in the Chayes-Machta-Redner representation of the zero-field Edwards-Anderson spin glass in high finite dimensions. For fixed symmetric iid couplings with $ 0<m=\mathbb{E}|J|<\infty$ , the first percolation onset is asymptotic to $ (2dm)^{-1}$ in periodic joint limits. For symmetric $ \pm1$ couplings, we give a computer-assisted dimension-22 certificate. For exponential-moment disorder, we also establish a percolating regime with exactly equal infinite-blue-sector densities and finite spin-glass susceptibility. In these periodic limits, persistent density imbalance would imply distinct spin-flip-related Gibbs states and a pressure cusp for a suitable finite local replica coupling, without requiring finite-blue cancellation. Proving imbalance remains open.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph), Probability (math.PR)
44 pages, 7 figures, 2 algorithms
Universal Response Functions in Driven Dissipative Tunneling Dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Universality in nonlinear nonequilibrium systems is typically expressed through scaling laws that render macroscopic behavior insensitive to microscopic details. Whether this universality survives when periodic forcing and nonlocal dissipative memory act simultaneously remains an open question in driven open dynamics. Here, we demonstrate that barrier-crossing processes in periodically driven dissipative systems are governed not merely by modified exponential scaling, but by an explicit two-parameter universal response function.
Within a semiclassical instanton framework incorporating Floquet modulation and Ohmic environmental coupling, the tunneling exponent factorizes into a system-dependent static contribution and a universal function of two dimensionless control parameters: normalized driving frequency and dissipation strength. This factorization arises from the combined modification of a single saddle-point trajectory and introduces no additional independent scaling variables.
Weak-to-moderate dissipation acts as a smooth dynamical renormalization of the effective action, preserving the saddle-point structure and enabling controlled analytical expansion. In the high-frequency regime, the response exhibits universal dynamical averaging, while an explicit integral representation establishes a continuous adiabatic to Floquet crossover. Direct numerical evaluation of the nonlocal instanton action confirms that the normalized tunneling exponent exhibits a universal dependence on the driving parameters across different model systems. These results identify driven dissipative barrier crossing as a distinct two-parameter universality class within nonlinear nonequilibrium dynamics and provide a predictive functional framework for response phenomena in driven systems with memory.
Statistical Mechanics (cond-mat.stat-mech)
9 pages, 4 figures , 2 tables
Published in Chaos 36,073105(2026) (editorial pick)
A rank-two spherical transform for eigenvector and singular-vector overlaps
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
We define a rank-two extension $ \mathcal{H}^{(2)}$ of the spherical $ \mathcal{H}$ -transform, together with its associated transform $ \mathcal{R}^{(2)}$ . For sums, both transforms are additive. The transform $ \mathcal{R}^{(2)}$ yields a $ 4\times4$ formula for the average product of two hermitized resolvents, and hence for off-diagonal eigenvector overlaps, recovering the Ginibre, elliptic, and bi-invariant formulas. We also treat correlated pairs of matrices, and obtain overlaps between their eigenvectors or singular vectors.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph), Probability (math.PR)
NTBuilder: Commensurate Construction of Nanotubes from Arbitrary Two-Dimensional Crystals and a Catalog of 20 Million Structures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Although tens of thousands of two-dimensional (2D) crystals are now known, the nanotubes they can form are usually constructed for individual materials, using procedures derived for graphene. Here, we develop a general theory of the rolling construction for arbitrary 2D crystals and implement it in \ntbuilder{} (NanoTube Builder), an open-source library with desktop and web interfaces. We express the size of the exact unit cell of a tube through the reduced form of a single rational number built from the lattice metric, which explains why triangular and square lattices always close with small cells, whereas rectangular, centered rectangular, and oblique lattices can require cells larger by many orders of magnitude. The optimal approximate cells are the best rational approximations of a second number, so that a cell small enough for first-principles calculations can be chosen with a controlled departure from periodicity, as in the biphenylene network, where such a cell is eight orders of magnitude smaller than the exact one. The 17 plane groups reduce to seven distinct chirality maps once rolling is taken into account, the rolling sense of layers without a horizontal mirror defines distinct tubes, and bonds formed or broken by curvature are detected pair by pair against the flat layer. The same framework assembles multiwalled tubes whose walls share one axial period, periodic bundles, and strained or twisted structures that remain periodic. Applied to 46,403 distinct 2D systems, it produced a public catalog of 20,334,372 nanotubes, of which 57.1% show no bond change upon rolling. All structures can be exported directly as input for first-principles and molecular dynamics codes.
Materials Science (cond-mat.mtrl-sci)
24 pages and 12 figures
Gradient-estimator design overcomes trainability barriers in neural-network-based variational optimization
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
Yi-Ran Xue, Rui Wang, Baigeng Wang, Chenan Wei
Neural networks provide expressive representations for scientific computing. However, even sufficiently expressive networks can suffer training failure in weak-gradient regimes, limiting their practical use in quantum many-body physics and ab initio quantum chemistry. Here we derive an unbiased direct gradient estimator and introduce the adaptive minimum-variance phase (AMVP) estimator for neural-network variational optimization. By improving the signal-to-noise ratio of weak gradients, these methods enable reliable scientific calculations where training previously failed, while substantially reducing computational cost. The framework enables compact networks to outperform larger and fine-tuned default standard-estimator models with over an order of magnitude less GPU time on correlated flux models, and ultimately exceed the density matrix renormalization group (DMRG) accuracy. It further achieves chemical accuracy in N$ _2$ bond breaking and, for the first time, in heavy-element I$ _2$ with explicit spin-orbit coupling. These results demonstrate that gradient-estimator design expands the capabilities of neural-network variational methods for accurate scientific computing.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el), Machine Learning (cs.LG), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
10 pages, 4 figures; partially supersedes arXiv:2606.13912
Existence and Uniqueness of Nearest Stealthy Hyperuniform Configurations from Random Initial Conditions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
We prove that, for almost every uniformly random configuration of $ N$ particles in a two-dimensional periodic square domain, there exists a unique nearest stealthy hyperuniform configuration, up to floppy-mode displacements, when a finite set of $ m$ low-$ k$ Fourier modes is constrained to vanish exactly. Under an explicit full-rank Jacobian assumption, the displacement component orthogonal to the tangent space of the finite-mode hyperuniform manifold is uniquely determined, while residual tangent-space degrees of freedom correspond to first-order floppy modes that preserve the constrained low-$ k$ density fluctuations. We restrict attention to the regime of constrained-mode fraction $ \chi=m/(dN)$ in which such configurations are known to remain disordered rather than crystallize. To corroborate this framework, we implement a gradient-based generator network that iteratively displaces particles to minimize a combined loss functional of hyperuniformity, short-range repulsion, and smoothness, and whose dynamics is expected to approximate the theory’s minimal orthogonal projection onto the hyperuniform manifold. The network drives generic random configurations toward disordered hyperuniform representatives, progressively suppressing long-wavelength density fluctuations as measured by the structure factor and number-variance exponent\textcolor{black}{, over a reciprocal-space window that extends well beyond the explicitly constrained modes and is bounded, as we show, by the structure-factor sum rule. Local bond-orientational analysis and the absence of Bragg peaks confirm that the resulting states remain disordered}. This integrated analytical and computational approach provides a rigorous geometric foundation for understanding stealthy hyperuniformity and for generating its disordered representatives from generic random configurations.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
From Ferroionic Instability to Domain Patterns at an Exposed Surfaces of Multiaxial Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
We analyze the formation of domain structures in multiaxial ferroelectrics with an open, electrochemically compensated surface. The model combines vector polarization, surface electrochemistry, electrostatics, compatible strain, and competitive adsorption on common sites. We construct homogeneous phase maps and analyze polarization instabilities, first assuming perturbations that are uniform through the film thickness and then allowing depth-dependent polarization profiles. Nonlinear continuation follows the growth of these modulations into developed domains. Optimization of their period and tests of their stability establish how the initial instability wavelength relates to the preferred spacing of an established domain structure. We also consider surface ordering above a stable, weakly anisotropic bulk as a constitutive limit relevant to ferroelectric relaxors, providing insight into possible origins of their periodic surface modulations. Surface energies with the same quadratic terms can produce the same initial instability but favor different developed states, including periodic domains and uniform in-plane polarization. This analysis provides a procedure for connecting the initial development of ferroelectric modulations to amplitude selection, wavelength adjustment, and the subsequent evolution of the resulting domain structures.
Materials Science (cond-mat.mtrl-sci)
A Hybrid Quantum Neural Network to Analyse Big Experimental Powder X-ray Diffraction Data
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
H. Dong, S.D.M. Jacques, M.Q. Hlatshwayo, E. Papoutsellis, K. Georgopoulos, A. M. Beale, A. Vamvakeros
Quantitative analysis of experimental powder X-ray diffraction data remains challenging when evaluating complex multiphase materials and noisy measurements. We introduce a hybrid quantum neural network framework designed to extract quantitative parameters, such as phase weight fractions and scale factors, directly from one-dimensional powder diffraction patterns without iterative refinement. The model combines noise-aware classical simulator pre-training with fast downstream fine-tuning on quantum processing unit features, ensuring stability against hardware decoherence. We demonstrate the practical utility of this approach by deploying the trained network onto an IBM quantum computer to analyse experimental X-ray diffraction computed tomography datasets from a three-phase solid oxide fuel cell containing ca. 10,000 patterns and a four-phase lithium-ion battery containing ca. 20,000 patterns). The network successfully reconstructs quantitative spatial phase maps in strong agreement with classical Rietveld refinement, paving the way for using quantum computing hardware to analyse real-world materials characterisation data.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
On the ratio between longitudinal and transverse Ioffe-Regel frequencies in glasses
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Licun Fu, Mingyu Zhu, Xinyu Chang, Lijin Wang
The temperature dependence of thermal conductivity in glasses differs characteristically from that in crystals, and is largely controlled by how sound waves are damped. The Ioffe-Regel (IR) frequency sets the high-frequency limit of well-defined sound waves. Although the transverse IR frequency has been established to coincide with the boson peak frequency and reported to be far below the longitudinal IR frequency, the quantitative relation between longitudinal and transverse IR frequencies has remained unknown. Here we examine this relation in two- (2D) and three-dimensional (3D) model glasses with vastly different stability. We observe that, in 3D glasses, the longitudinal-to-transverse IR frequency ratio is approximately equal to the ratio of the low-frequency transverse to longitudinal sound attenuation coefficient, whereas this correspondence is not observed in 2D glasses. Moreover, we find that the glass stability strongly controls the longitudinal-to-transverse IR frequency ratio in both 2D and 3D glasses: the ratio decreases significantly with increasing glass stability and approaches unity for the most stable glasses under study. Accordingly, in sufficiently stable glasses, the longitudinal sound attenuation should be comparable to the transverse attenuation, and therefore cannot be treated as negligible, challenging common assumptions adopted especially in theoretical studies. Our work is another demonstration of the glass stability as a key parameter for investigating glass properties, and cautions against simply extrapolating observations from poorly annealed glasses to stable glasses.
Soft Condensed Matter (cond-mat.soft)
9 pages, 6 figures
Raman scattering in cuprate oxychlorides high-temperature superconductors single-crystals
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Chafic Fawaz (NEEL - MagSup), Yingzheng Gao (NEEL - MagSup), Luca Laveder (NEEL - MagSup), Lorenzo Menon (NEEL - MagSup), Owen Moulding (NEEL - MagSup), Rolf Heid (IQMT), Blair W Lebert (IMPMC DEMARE), Christophe Bellin (IMPMC PHYSIX), Keevin Beneut (IMPMC), David Santos-Cottin, Ikuya Yamada (OMU), Yuichi Okazaki (OMU), Hajime Yamamoto (TITECH), Masaki Azuma (TITECH), M.-A. Méasson (NEEL), Matteo d’Astuto (NEEL - MagSup)
We investigate the Raman response of sodium-doped cuprate oxychloride Na$ _x$ Ca$ _{2-x}$ CuO$ _2$ Cl$ 2$ high-temperature superconductors across their entire phase diagram, from the antiferromagnetic to the superconducting region. In addition to the expected Raman-active phonon modes, we detect several additional modes that can be interpreted as being excited via a resonance process enabled by strong electron–phonon coupling. To verify the resonance effect, the Raman response at different incident photon energies was measured. At high energies, there is a well-defined $ B{1g}$ mode in the antiferromagnetic phase, which can be interpreted as a bimagnon We follow its temperature and doping dependence, providing information on the multimagnon excitation in these cuprates, which can be theoretically linked to the exchange interaction.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Bootstrap certification of string order in quantum spin chains
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Sagnik Banerjee, Haoyu Guo, Debanjan Chowdhury
The many-body bootstrap certifies ground-state properties by minimizing energy over correlators constrained only by positivity, without any variational wavefunction. Its cost, however, grows exponentially with the size of the operators involved, placing the long-range string correlators that diagnose topological phases out of reach. We overcome this by treating string operators as primary objects: bare and endpoint-dressed strings satisfy a closed operator algebra with one another and with local words, yielding a semidefinite program whose cost grows only polynomially with string length. A single computation then yields estimates of string correlators of all lengths. Rigorous two-sided bounds are obtained for each target string once the ground-state energy is pinned within a window. When benchmarked against density-matrix renormalization group computations on the cluster Ising and spin$ -1$ Heisenberg chains, the method certifies the nonlocal string order of the cluster and Haldane phases directly from the Hamiltonian. Our rigorous certification of string order parameters reveal that the sharpness of the bounds is set by which operators enter the calculation, not by their length alone. By exploiting algebraic closure of strings and local words, our framework lifts spatially extended observables into polynomially tractable bootstrap variables, opening up a route to wavefunction-free certification of nonlocal order in quantum many-body systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Main text: 9 pages, 5 figures. Supplementary material: 8 pages, 5 figures
A low-symmetry ground state of dense two-dimensional hydrogen
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Cesare Cozza, Chris J. Pickard, Guglielmo Mazzola
Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic crystals. This preference already emerges with classical nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although crystals with very large primitive cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
Materials Science (cond-mat.mtrl-sci)
Laser-Ablated Au Electrodes with Preferred Orientation and Flat Interface on Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Ambrose Seo, Richard Lai, Sujan Shrestha, Tina Tong, Joseph W. Brill, Menglin Zhu, Chris Chae, Jinwoo Hwang
Gold (Au) thin-film electrodes deposited on oxides by pulsed laser deposition (PLD) exhibit distinctive structural properties compared with thermally evaporated Au films. While thermally evaporated Au forms polycrystalline films with randomly oriented grains, PLD-grown Au films show a strong preferred [111] orientation perpendicular to the substrate surface, likely due to the energetic nature of the laser-ablated Au plume. High-resolution transmission electron microscopy reveals atomically flat interfaces between the PLD-grown Au electrodes and epitaxial oxide thin films, separated by nanometer-scale gaps comparable to interlayer spacings in van der Waals materials. The highly ordered microstructure and flat interfacial morphology result in enhanced adhesion of the Au films to oxide surfaces. These results demonstrate that PLD can produce both high-quality Au electrodes and oxide thin films within a single deposition platform, offering improved interfacial control and potential benefits for a wide range of oxide electronic and functional devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
9 pages, 4 figures
Current Applied Physics 92, 162 (2026)
Mobility-lifetime relation links photodegradation in spin-coated and gravure-printed organic solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Maria Saladina, Paul Weitz, David Holzner, Chen Wang, Robert Eland, Svitlana Taranenko, Christopher Wöpke, Toni Seiler, Fabian Eller, Doyoung Sun, Alexander Ehm, Bekcy Joseph, Pelin Çiloğlu, Carmen Tretmans, Andreas Willert, Harald Kuhn, Roderick C. I. Mackenzie, Jan-Frederik Pietschmann, Martin Stoll, Yana Vaynzof, Dietrich R. T. Zahn, Safa Shoaee, Eva M. Herzig, Arved Carl Hübler, Thomas Heumüller, Christoph J. Brabec, Carsten Deibel
The degradation mechanisms of organic solar cells (OSCs) have been studied primarily in spin-coated, laboratory-scale devices, whereas scalable processing modifies the device architecture, active-layer morphology, and underlying charge-transport and recombination properties. Whether these changes also alter how solar cells degrade remains unclear. Here, we compare spin-coated and fully roll-to-roll-compatible gravure-printed PM6:Y12 solar cells during $ \sim$ 1000 h of continuous illumination. Despite distinct initial properties and degradation signatures, the loss of power-conversion efficiency systematically follows the mobility-lifetime product $ \mu\tau$ . Remarkably, ageing of the printed devices increases the recombination lifetime while strongly reducing charge-carrier mobility, showing that a longer lifetime alone does not imply improved device performance. The mobility reduction is accompanied by decreased PM6 lamellar order, whereas the additional open-circuit voltage loss originates predominantly from increased non-radiative recombination. Dark recovery further reveals a metastable contribution specific to the printed architecture. These results identify the mobility-lifetime product as a unifying physical descriptor for photodegradation, linking ageing-induced microscopic changes to macroscopic performance loss across spin-coated and scalable printed OSCs.
Materials Science (cond-mat.mtrl-sci)
Revealing epitaxial relationships at Ga$_2$O$_3$ interfaces with p-type oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Anna Sacchi, Krishna Acharya, Michelle A. Smeaton, Renae N. Gannon, Vladan Stevanovic, Steven R. Spurgeon, M. Brooks Tellekamp, Andriy Zakutayev
p-type oxide contact layers such as Cr$ _2$ O$ _3$ and NiO are attracting increasing interest in pn-heterojunctions with n-type monoclinic $ \beta$ -Ga$ _2$ O$ _3$ for high-power electronic devices and other extreme environment applications. However, scientific understanding of their epitaxial relationships remains incomplete. In this work we investigate the epitaxial relation of Cr$ _2$ O$ _3$ and NiO layers to (001) and ($ \bar{2}$ 01) out-of-plane oriented Ga$ _2$ O$ _3$ substrates. Surprisingly, we find that, for the most commercially relevant (001)-orientation of the Ga$ _2$ O$ _3$ substrate, the epitaxial relationships are Cr$ _2$ O$ _3$ (0001) and NiO (111) $ \parallel$ Ga$ _2$ O$ _3$ (101), both at the non-intuitive $ \chi$ = 22.5 $ ^\circ$ angle with respect to the substrate normal. We explain this unusual discovery by the interfacial atomistic bonding dominated by oxygen sublattice equivalence of these Cr$ _2$ O$ _3$ and NiO polar surface orientations to the tilted Ga$ _2$ O$ _3$ (101), rather than Ga$ _2$ O$ _3$ (001) substrate surface planes. Furthermore, we assign the in-plane orientation for Cr$ _2$ O$ _3$ on ($ \bar{2}$ 01)-oriented Ga$ _2$ O$ _3$ as: Cr$ _2$ O$ _3$ $ [12\bar{3}0]$ $ \parallel$ Ga$ _2$ O$ _3$ $ [010]$ with two in-plane rotational domains. Interface modeling confirms the in-plane orientation for Cr$ _2$ O$ _3$ /$ (\bar{2}01)$ Ga$ _2$ O$ _3$ and shows that strained O-terminated Ga$ _2$ O$ _3$ $ (\bar{2}01)$ surfaces have the lowest interfacial energy with Cr$ _2$ O$ _3$ (0001). Beyond establishing the specific epitaxial relationships for Cr$ _2$ O$ _3$ and NiO on Ga$ _2$ O$ _3$ , this work provides a systematic methodology for the unambiguous structural characterization of heterointerfaces involving materials with markedly different crystal symmetries.
Materials Science (cond-mat.mtrl-sci)
Experiments and Modeling of Defect Dynamics and BTI Behavior in Doped InO TFTs during $400^\circ$C Post-Processing Forming Gas Annealing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Yu-Hsin Kuo, Chengyang Zhang, Priyankka Ravikumar, Sanghyun Kang, Taeyoung Song, Marco Villena, Luca Larcher, Hwan Kim, Minji Hong, Pilsang Yun, Gaurav Thareja, Shimeng Yu, Daewon Ha, Suman Datta, Julia Medvedeva, Asif Khan
We investigate the impact of a monolithic three-dimensional (M3D) integration process-critical $ 400^\circ$ C post-processing forming gas anneal (FGA) on the electrical performance, reliability, and defect evolution of oxide-channel thin-film transistors (TFTs), combining systematic experiments with density-functional-theory (DFT)-based liquid-quench molecular-dynamics (MD) simulations. Indium tungsten oxide (IWO) TFTs are employed as a model system and encapsulated with a thin 3 nm Al$ _2$ O$ _3$ / 3 nm HfO$ _2$ hybrid layer that effectively suppresses external hydrogen ingress. We reveal a non-monotonic evolution of device behavior during FGA, governed by initial densification followed by partial crystallization. Short-duration FGA (10 min) induces channel densification and the formation of shallow, delocalized defect states, leading to pronounced positive bias temperature instability (PBTI) degradation and the emergence of a characteristic transfer-curve “kink.” With prolonged annealing (>40 min), partial crystallization of the oxide channel occurs, stabilizing hydrogen in deep, localized defect states, suppressing hydrogen mobility, and restoring device reliability. As a result, the PBTI shift is reduced to 10.4 mV after 2000 seconds of stress, accompanied by complete elimination of the transfer-curve kink. These findings provide a mechanistic understanding of hydrogen-defect interactions during high-temperature post-processing FGA and demonstrate that appropriate hydrogen-blocking encapsulation enables oxide-channel TFT integration without compromising electrical performance or reliability.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
9 pages, 13 figures. Author accepted manuscript
IEEE Transactions on Electron Devices, vol. 73, no. 5, pp. 3140-3148 (2026)
Acoustic dip in the effective temperature of hot Brownian motion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Mayank Srivastava, Dipanjan Chakraborty
A hot Brownian particle is driven by thermal fluctuations from a
nonuniformly heated solvent and therefore obeys a
fluctuation-dissipation relation with a frequency-dependent
effective temperature. Existing theories assume an incompressible
solvent. We show that finite sound speed qualitatively changes this
effective temperature in the kinetic regime. Solving the
compressible fluctuating-hydrodynamic problem for a heated sphere,
we find that the effective noise temperature develops a pronounced
acoustic dip when the sound wavelength becomes comparable to the
particle radius. The dip occurs because weakly attenuated
longitudinal modes carry mechanical energy away from the heated
surface before it is dissipated, so that the dissipation is weighted
by colder regions of the temperature field. Its position is set by
$ a\omega/c=\mathcal{O}(1)$ , while its depth is controlled by the
dimensionless viscous-acoustic attenuation length $ a_c/a$ . The
result identifies an acoustic window in hot Brownian motion in which
compressibility lowers, rather than raises, the kinetic noise
temperature.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Diffusion with stochastic resetting in the presence of a delta killing trap: Drift-controlled survival regimes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
We study a one-dimensional diffusive particle subject to stochastic resetting to its initial position, in the presence of an imperfect, localized target that can absorb (kill) the particle, modeled by a delta-function killing rate. The central question is how stochastic resetting competes with drift-induced transience and the target’s finite reactivity. Exact Laplace-space expressions are derived for the non-normalized propagator and survival probability, for arbitrary diffusion coefficient $ D$ , resetting rate $ r$ , and killing strength $ k$ , first in the absence of drift and then under a constant drift. The long-time behavior separates into distinct regimes. Without resetting, unbiased diffusion exhibits the recurrent algebraic survival law $ S(t)\sim t^{-1/2}$ , whereas any nonzero drift renders the motion transient with respect to the target and leaves a nonzero ultimate survival probability. By contrast, any $ r>0$ and $ k>0$ repeatedly renews encounters with the target and restores eventual absorption, yielding an exponential survival law $ S(t)\sim A e^{-\theta t}$ . The decay rate $ \theta$ is given by the dominant (rightmost) pole of the Laplace transform, and the surviving density converges after normalization to an explicit quasi-stationary profile. The driftless and perfectly absorbing limits recover standard resetting results. These formulas provide a unified description of the crossover between recurrence-controlled, transience-controlled, and renewal-controlled survival.
Statistical Mechanics (cond-mat.stat-mech)
27 pages, 4 figures
Two-Stage Ordering Kinetics in Binary Mixtures of Ellipsoidal Particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Parameshwaran A, Sanjay Puri, Bhaskar Sen Gupta
We investigate the nonequilibrium phase-ordering kinetics of a binary mixture of uniaxial ellipsoidal particles interacting via the anisotropic Gay-Berne potential using large-scale molecular dynamics simulations. Following a temperature quench from the isotropic and homogeneous phase into the coexistence region, the system exhibits two distinct ordering processes occurring on different time scales. At first, rapid orientational ordering leads to the formation and coarsening of nematic domains, characterized by dynamical scaling, generalized Porod-law behavior, and a growth law $ \ell(t) \sim t^{1/2}$ consistent with nonconserved order-parameter dynamics. Later, the system undergoes binary phase separation driven by compositional fluctuations. This compositional ordering process shows a transition from diffusive growth $ \ell(t) \sim t^{1/3}$ to hydrodynamic regimes, with finite-size scaling analysis indicating asymptotic viscous growth $ \ell(t) \sim t$ . Despite the presence of global orientational order, the phase-separation kinetics remains effectively isotropic. These results demonstrate a clear separation between orientational and compositional ordering dynamics, governed by distinct conservation laws, and provide a unified framework for understanding phase ordering in anisotropic particle systems.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)
Approaching the Inverse Neutron Scattering Problem with Neural Networks
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Jingyi Luo, Fletcher Williams, Ang-Kun Wu, David Dahlbom, Cristian D. Batista, Hao Zhang
Determining the microscopic Hamiltonian of a quantum magnet from inelastic neutron scattering measurements remains a central challenge in condensed matter physics. While the dynamical spin structure factor contains, in principle, sufficient information about the underlying interactions, extracting Hamiltonian parameters from experimental spectra constitutes a highly nontrivial inverse problem due to the large parameter space and the presence of experimental noise. Here we demonstrate that neural networks can efficiently solve this inverse problem for a broad class of quantum magnets. As a benchmark, we consider an eight-parameter family of honeycomb lattice Heisenberg spin models in the fully polarized phase, where the dynamical spin structure factor can be computed exactly within linear spin-wave theory. Using a large synthetic dataset of neutron scattering spectra, we train neural networks to infer the underlying Hamiltonian parameters directly from the dynamical response. We compare the performance of three different architectures—fully connected neural networks (FCNNs), one-dimensional convolutional neural networks (CNN1Ds), and two-dimensional convolutional neural networks (CNN2Ds)—and find that all achieve high predictive accuracy. Remarkably, the trained models remain robust in the presence of substantial experimental uncertainty, reliably recovering the Hamiltonian parameters even when the input spectra are contaminated by random noise with amplitudes reaching $ 10%$ of the signal intensity. Our results establish machine learning as a powerful framework for quantitative Hamiltonian reconstruction from neutron scattering data and provide a practical route toward automated characterization of quantum magnetic materials.
Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 12 figures
Intermittency in Wind-Driven Fires
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Laurent Hébert-Dufresne, Aanjaneya Kumar, S. Redner
We construct a wind-driven forest-fire model in one dimension in which a fire can jump gaps between trees to ignite disjoint downwind forests. The size of a gap that a fire can jump depends on the fire intensity, which increases as the fire propagates through trees and diminishes as the fire jumps gaps. Trees grow on empty sites at rate $ r$ and lightning strikes each site with rate $ f$ . When $ f\ll r/L$ , where $ L$ is the system length, lightning is sufficiently rare that quasi-deterministic dynamics arises where all trees are consumed when a lightning-induced fire occurs. For $ f\gg L^{-\mu}$ with $ \mu\approx 0.8$ , lightning is sufficiently frequent that a steady state is reached, but with unexpected behaviors for the forest- and gap-size distributions. Intermittency arises in between these regimes, with coexisting temporal domains of deterministic and chaotic dynamics.
Statistical Mechanics (cond-mat.stat-mech), Physics and Society (physics.soc-ph)
5 pages, 6 figures, revtex4 format
Compressive Splitting in Brittle Solids: The Inverse of Wrinkling in Sheets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Maryam Khodadad, Francois Barthelat, John D. Clayton, George Gazonas, Kaushik Dayal
Axial splitting is the dominant failure mode of brittle solids under compression, yet its mechanical origin remains unclear. We show that clamped loading platens suppress lateral Poisson expansion, generating boundary-induced tensile stresses at the specimen interior – the compressive analog of wrinkling in stretched sheets. This mechanism provides a predictive strength law, relating axial splitting to tensile strength, geometry, and confinement pressure. This is validated against diverse materials ranging from rocks to ceramics, establishing axial splitting as a geometry-controlled elastic process rather than a stochastic flaw problem.
Materials Science (cond-mat.mtrl-sci)
To appear in Physical Review Letters
Vanadium doping induced valley asymmetries in WS$_2$ monolayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Frederico B. Sousa, Boyang Zheng, Elizabeth Grace Houser, Paulo E. Faria Junior, Zhuohang Yu, Alessandra Ames, Gabriel A. D. Souza, Mingzu Liu, Gilmar Eugenio Marques, Leandro M. Malard, Mauricio Terrones, Vincent H. Crespi, Marcio D. Teodoro
Transition metal dichalcogenide (TMD) monolayers offer an innovative platform for encoding and manipulating information through the valley degree of freedom. While unique valley-related physical phenomena have been reported so far, practical applications still require advanced control over the valley polarization efficiency and the valley Zeeman effect. Recently, the introduction of spin-polarized metal atoms as substitutional defects was reported to break the time-reversal symmetry in TMD monolayers, consequently inducing a room-temperature ferromagnetic ordering and enhancing the valley-dependent optical responses. Here, we report valley asymmetries for vanadium-doped WS$ _2$ monolayers. With a given magnetic polarization, one valley exhibits larger Zeeman slope and degree of circular polarization than the other valley. Additionally, the overall degree of circular polarization in the doped samples is approximately twice that of the pristine WS$ _2$ monolayer. Density functional theory calculations in the doped structure show that different energy shifts in conduction band edges due to spin-dependent hybridization lead to different exciton energies between valleys, which is consistent with the experimental observations. Our results pave the way for valleytronic technologies based on defect-engineered two-dimensional materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Structural and magnetic properties of TbCuAs$_2$ studied by X-ray and neutron scattering
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
M. G. Kim, T. Heitmann, S. Boney, C. Neupane, R. Acevedo-Esteves, A. Sapkota, D. Evans, P. C. Canfield, C. Nelson, E. D. Mun, J.-W. Kim
We investigated antiferromagnetic metal TbCuAs$ _2$ , which exhibits an anomalous resistivity upturn at low temperatures. This resistivity upturn has been proposed to originate from the material’s magnetic ground state; however, the precise nature of the antiferromagnetic ordering in this compound has not been previously established. Here, we present a combined single crystal neutron diffraction, X-ray resonant magnetic scattering, and single crystal X-ray diffraction study of TbCuAs$ _2$ . These measurements unambiguously determine the Tb magnetic moment direction, the antiferromagnetic arrangement along high symmetry directions, the interplay between structure and magnetism, and their temperature dependence. Our observations are compared with previous studies on sister compounds in the rare-earth copper arsenide family ($ R$ CuAs$ _2$ , $ R$ = Sm and Gd), which also displays resistivity anomalies. We suggest a common underlying physics governing the structural and magentic properties of rare-earth copper arsenides that exhibit low-temperature resistivity anomalies.
Strongly Correlated Electrons (cond-mat.str-el)
LiNiO2/NiO Phase Prediction Using Artificial Neural Networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Jonas Scheunert, Shamail Ahmed, Thomas Demuth, Andreas Beyer, Kerstin Volz
In the realm of material analysis, identifying different material phases is of key importance. Artificial intelligence in the form of neural networks provides a very fast and, once trained, computationally inexpensive method for analysing large amounts of image data, like the sets of diffraction patterns generated during four-dimensional scanning transmission electron microscopy (4DSTEM) dataset acquisition. In this work, we train multiple network architectures on images of this type to distinguish between the phases of LiNiO2 and NiO, an important and challenging distinction in the lithium-ion battery community, since the formation of NiO limits battery capacity. We test both classical convolutional neural networks (CNNs) and different forms of vision transformers (ViTs). Our networks are trained on synthetic images and tested on experimentally recorded diffraction patterns. Additionally, we also investigate the decision-making of our networks using the GradCAM method. We test our networks on both synthetic as well as experimental diffraction patterns. Our networks exhibit very robust results, especially when dealing with highly varying data, an area where traditional template-matching methods typically struggle.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Probing $d$-wave pairing in the $t$-$t’$-$U$ Hubbard model with tensor-backflow wave functions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Building on the recently developed tensor-backflow method, which accurately describes energies and stripe states in the Fermi-Hubbard model, we investigate $ d$ -wave pairing in the two-dimensional $ t$ -$ t’$ -$ U$ Hubbard model. For the $ 8\times8$ lattice, we improve the wave function using symmetry projections followed by one Lanczos step, whereas for the $ 12\times 12$ and $ 16\times 16$ lattices, we apply one Lanczos step without symmetry projection. We focus primarily on the parameter regime with filling $ n=0.875$ , on-site repulsion $ U=8$ and next-nearest-neighbor hopping $ t’=-0.2t$ , a regime in which enhanced $ d$ -wave pairing has been reported. The resulting energies are competitive with those obtained using state-of-the-art neural quantum states. For example, on a $ 16\times 16$ lattice with periodic boundary conditions, the tensor-backflow wave function after one Lanczos step without explicit symmetry enforcement achieves a relative energy difference of $ 4.4\times 10^{-3}$ from the symmetry-preserving neural quantum state result. From the real space pair correlations, for $ t’=-0.2t$ , we observe stronger $ d$ -wave pair correlations together with the characteristic relative sign between horizontal and vertical bond-pair components. Compared with $ t’=0$ , finite negative $ t’$ increases the spectral weight of the corresponding pair-density matrix, which indicates the enhanced overall $ d$ -wave pair fluctuations. The leading eigenvalue is enhanced on the $ 8\times8$ lattice for both with and without symmetry projections. For larger lattices such as $ 12\times 12$ and $ 16\times 16$ , the leading pair-density matrix spectral weight is distributed among several nearly degenerate eigenmodes rather than being concentrated in a single dominant mode. This indicates enhanced and more broadly distributed $ d$ -wave pair fluctuations, but no single eigenvalue exhibits the extensive scaling required for ODLRO.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Extreme-Scale Ising Machines with Cluster Mean-Field Theory
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
Xiuqi Zhang, Shuvro Chowdhury, Shaila Niazi, Christian Z. Pratt, Navid Anjum Aadit, Kerem Y. Camsari
Scaling analog and digital Ising machines to larger problems requires overcoming finite device capacity and the cost of communication between devices. We present cluster mean-field theory (CMFT), a framework that partitions a large interaction graph into clusters sized to fit available hardware. Each cluster performs local updates independently, while interactions across cluster boundaries enter through periodically updated effective biases computed from boundary-spin averages. To reduce the error introduced by fixed cluster boundaries, we introduce dynamic partitioning, which cycles through multiple partitions so that interactions approximated by mean fields at one stage can act through instantaneous spins at another. On three-dimensional spin glasses and planted Pegasus instances, dynamic CMFT exhibits power-law decay of residual energy over sweep budgets. This shows that solution quality continues to improve with computational effort despite the mean-field approximation. An automated graph partitioner combined with a weighted recovery ratio provides a practical heuristic for selecting partition combinations on graphs without natural cut directions. We demonstrate CMFT on four GPUs with approximately four million p-bits, reaching comparable energy densities up to 15 times faster than a single-GPU implementation of the full graph. By coupling locally evolving clusters through programmable effective biases, CMFT provides a route to extreme-scale Ising machines on both analog and digital hardware.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Distributed, Parallel, and Cluster Computing (cs.DC), Emerging Technologies (cs.ET)
15 pages, 10 figures including Supplementary Information
Highly Lattice-Mismatched Selective Area Epitaxy and Coalescence of PbSe Nanostructures on GaAs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Ashlee M. García, Hosni A. Kaissi, Jarod E. Meyer, Kira J. Martin, Maksim Gomanko, Laura A. Stern, Pooja D. Reddy, SeongJin Park, Wilson J. Yánez-Parreño, Sergey M. Frolov, Vlad S. Pribiag, Kunal Mukherjee
Selective area growth of PbSe has the potential to realize deterministic placement of high-density, defect-tolerant nanostructure networks toward a scalable quantum platform. PbSe is a narrow bandgap semiconductor with advantageous (opto)electronic properties that has been shown to have a desirable defect-tolerance, enabling bright emission even when grown on highly-dissimilar platforms, and could be leveraged in combination with selective growth for site-selective quantum emitters and low-disorder hybrid nanowire networks. In this work, we achieve site-selective growth of well-faceted and ordered PbSe nanostructures, despite a large 8% lattice mismatch. Structural and morphological characterization reveal that $ >$ 99% of selectively grown islands within 100 nm opening are single-orientation and cube-on-cube oriented with sub-nm root-mean-square surface roughness. Defect analysis showed that 74% of the islands and 86% of the coalesced regions between different mask openings were free of threading dislocations. These PbSe islands achieved equivalent emission in the mid-infrared despite having a higher surface-to-volume ratio than the planar control. Further, we present a gate-tunable two-terminal Josephson junction fabricated from the PbSe nanowires grown with conditions identified in this study. The combination of the accessible selective growth regime, morphological control of island growth and demonstrations of optical and electrical transport properties indicates promise for PbSe SAG as a defect-tolerant scalable quantum platform.
Materials Science (cond-mat.mtrl-sci)
26 pages, 5 figures
GRAINSMITH: A Generator of Polycrystalline Models for Atomistic Simulations with Statistical and Grain-Boundary Morphology Control
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Atomistic studies of grain-boundary engineering, grain-size effects and dopant enrichment require reproducible models with prescribed microstructural features. We present GRAINSMITH, an open-source Python package for generating statistically controlled polycrystalline models with selectable grain-boundary morphologies for molecular dynamics and subsequent relaxation. Within supported feature combinations, a single configuration specifies grain-size and volume distributions, crystallographic texture, boundary-area-weighted disorientation-angle distributions, phase composition and grain-boundary dopant placement. Crystal construction supports 230 crystallographic space groups. Periodic Voronoi and volume-targeted Laguerre tessellations provide planar boundaries, while distinct geometry backends generate smoothly curved and band-limited self-affine boundaries. A registry of twenty-six checks assesses applicable inputs, construction properties and outputs. Each run exports LAMMPS data and Extended XYZ files together with structural and statistical descriptors and machine-readable provenance. For a fixed software version and computational environment, the configuration and random seed determine byte-reproducible atomic configurations and scientific data across supported worker counts. By combining statistical specification, boundary-morphology control and reproducible atomistic output, GRAINSMITH supports systematic studies of microstructural effects and quantitative comparisons across generated models.
Materials Science (cond-mat.mtrl-sci)
22 pages 7 figures
Electrical Probing of Dark Excitons through Microwave Permittivity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Alex Stram, Zhida Liu, Ziheng Zhang, Yangchen He, Xuejian Ma, Kyoung Pyo Lee, Lisa Frammolino, Fuxiang Chen, Robert J. Boyd, Sirapas Tangton, Anand Swain, Kan Yao, Kenji Watanabe, Takashi Taniguchi, Yuebing Zheng, Chih-Kang Shih, Daniel Rhodes, Li Yang, Xiaoqin Li, Keji Lai
Excitons in atomically thin semiconductors are almost always probed through their optical signatures, because the short lifetimes of these transient quasiparticles are generally assumed to preclude electrical detection. Here we show that photoexcited excitons in monolayer tungsten disulfide produce a large, optically tunable permittivity at gigahertz frequencies, and that the effect provides a contact-free electrical route to imaging dark excitons at the nanoscale. Using laser-illuminated microwave impedance microscopy, we find that high-purity encapsulated flakes exhibit a purely dielectric response resonant with the exciton spectrum, whereas defect-rich samples are governed by conventional photoconductivity. Spatial mapping of diffusion and sublinear power dependence identify long-lived dark excitons as the dominant contributors, and first-principles modelling of exciton polarizability reproduces the measured susceptibility. Our results establish excitons as optically tunable dielectric elements and introduce microwave microscopy as a direct electrical probe of dark-exciton transport with sub-100 nm resolution.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
17 pages, 4 figures
Three-dimensional atom-by-atom measurement of interface diffusion dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Doojin Park, Hyesung Jo, Yongmin Kwon, Seokjo Hong, Jaewhan Oh, Youngjoo Whang, Eunjik Lee, Gu-Gon Park, Sang Woo Han, Yongsoo Yang
Diffusion at interfaces governs how materials and devices form, evolve and function. It is usually measured through smooth concentration profiles and bulk transport coefficients, which average over the discrete atomic rearrangements. At nanoscale interfaces only a few atomic layers wide, however, such coarse-graining obscures the local three-dimensional (3D) atomic transport, and scalar diffusion coefficients cannot fully describe species-, layer- and facet-resolved redistribution. The essential observable is the discrete 3D redistribution of atoms themselves, beyond an averaged profile. Here we combine micro-electro-mechanical systems (MEMS) pulse-quench heating with atomic electron tomography (AET) to reconstruct five 3D atomic configurations of the same coherent Pd@Pt core-shell nanoparticle, each corresponding to a well-defined thermal state. Species-conserving one-to-one assignment links neighbouring configurations, and labelled reference simulations correct the displacement bias caused by indistinguishable same-species atoms. The corrected Pd diffusivities follow Arrhenius behaviour, giving an apparent activation energy of 1.10 eV, consistent with migration-limited vacancy-mediated transport. Atomic-layer transition statistics further show that increasing 3D mobility can coexist with declining net chemical transfer and reveal facet-dependent pathways hidden by the scalar diffusivity. Together, these measurements establish a 3D atom-by-atom framework that connects identity-corrected mobility to species-, layer- and facet-resolved transport at buried nanointerfaces.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
40 pages, 4 figures, 11 supplementary figures
Comment on “Topography of Fermi arcs in t-PtBi$_2$ using high-resolution angle-resolved photoemission spectroscopy” arXiv:2503.08841 (cond-mat)
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy have established surface superconductivity in the Weyl semimetal t-PtBi$ _2$ , whereas O’Leary et al. concluded from an independent ARPES experiment that superconducting signatures are absent above 3 K. Here we reanalyze the complete deposited data of O’Leary et al. Using only experimentally determined momentum-distribution-curve (MDC) maxima, energy-distribution-curve (EDC) peak positions, and leading edges, we find a strongly anisotropic low-energy gap and dispersion back-bending that closely reproduce the magnitude and angular dependence reported independently by Changdar et al. We further show that the temperature-dependent data of Ref.~\cite{Oleary} originate from the other surface termination and were presented using temperature-dependent energy translations, momentum translations, and momentum rescalings. Registering the original temperature-dependent datasets using the metallic bulk Fermi cutoff reveals finite gaps of approximately 2, 2, 1, and 0.8 meV at the four Fermi crossings. Thus the independently acquired data of O’Leary et al., obtained on different samples and with a different photon energy, confirm rather than contradict the previously reported anisotropic superconducting gap and additionally show that an anisotropic low-energy suppression persists to 19 K.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Comment on arXiv:2503.08841
Pressure-induced unconventional charge-density-wave states in kagome metal AV3Sb5 (A = K, Rb, Cs)
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Zhimian Wu, Linpeng Nie, Ye Yang, Kuanglv Sun, Huachen Rao, Dan Zhao, Zhongjun Li, Tao Wu, Xianhui Chen
Since the discovery of charge density wave (CDW) and superconductivity, kagome metal AV3Sb5 (A = K, Rb, Cs) provides a new platform for exploring novel many-body quantum phenomena. In CsV3Sb5, a stripe-like CDW with commensurate wave vector q = 3/8 was observed under moderate pressures, which leads to a peculiar superconducting double-dome behavior in pressure-dependent phase diagram. Previous density functional theory (DFT) calculations indicate that the pressure-induced stripe-like CDW is beyond conventional phonon softening scenario, suggesting a nontrivial role of electronic correlations. However, an in-depth understanding for the pressure-induced unconventional CDW remains elusive. Here, we performed pressure-dependent 51V nuclear magnetic resonance (NMR) measurements on KV3Sb5 and RbV3Sb5. Although the superconducting double-dome behavior is absent in pressurized KV3Sb5 and RbV3Sb5, a pressure-induced CDW phase, ascribed to a possible incommensurate triple-Q CDW, is identified by NMR spectra in both materials, indicating that the pressure-induced unconventional CDW beyond DFT calculations is a common feature for kagome metal AV3Sb5. In contrast to the stripe-like CDW, the pressure-induced incommensurate triple-Q CDW does not strongly suppress the superconducting temperature (Tc) but coincide with an almost plateau behavior at intermediate pressure regime in the pressure-dependent superconducting phase diagram. Furthermore, by systematically analyzing the Korringa relation between Knight shift and nuclear spin-lattice relaxation rate in AV3Sb5, van Hove singularities (vHSs) driven electronic fluctuations are revealed as an effective knob for the pressure-induced unconventional CDW. Finally, our present findings underscore the pressure-induced unconventional CDW as a novel correlated quantum state in kagome metal AV3Sb5.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
39 pages, 20 figures
Photoresist-Free Lithography via Light-Induced Redox Patterning of Oxide Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Johannes Frantti, Yukari Fujioka, Christopher Rouleau, Alexander Puretzky, Ilia Ivanov
Lithographic patterning of nanoscale devices typically depends on photoresists, wet processing and multistep pattern-transfer workflows that impose both environmental and scaling constraints. Focused laser irradiation of (Ni,Co)1+2xTi1-xO3 under a reducing atmosphere drives localized oxygen removal, directly converting the insulating oxide into embedded metallic features without etching or chemical processing. Here we demonstrate a photoresist-free patterning method based on light-induced redox transformations in (Ni0.4Co0.6)3O3 (x = 1) thin films. Our results indicate that the transformation is self-limiting, as the high optical absorption of the emerging metallic phase restricts further energy penetration and confines the reduction front, producing conductive layers with electrical properties comparable to bulk metals. This reversible, orientation-preserving transformation is characteristic of a topotactic redox process, enabling direct nanoscale patterning without photoresists. The process is reversible through re-oxidation and is compatible with standard semiconductor wafer substrates. The role of Ti as a reduction inhibitor is discussed. These results establish a route to direct nanoscale patterning based on controlled redox chemistry, offering a potential alternative to conventional lithography for functional thin-film materials.
Materials Science (cond-mat.mtrl-sci)
Device contacts as spin-state selectors for silicon vacancies in 4H-SiC
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Aurora Teien, Maria Mendes Martins, Andreas Gottscholl, Axel Erlebach, Piyush Kumar, Erlend Lemva Ousdal, Viktor Bobal, Augustinas Galeckas, Thomas Prokscha, Hannes Kraus, Corey J. Cochrane, Ulrike Grossner, Lasse Vines, Marianne Etzelmüller Bathen
Optically addressable defect spins in wide band gap semiconductors are promising building blocks for scalable quantum technologies. Yet, the consequences of conventional contact schemes used in semiconductor device integration for the quantum spin environment remain largely unexplored. Using the silicon vacancy (V$ _\mathrm{Si}$ ) in silicon carbide (SiC) as a model system, we show that a widely used contact metal, nickel (Ni), intrinsically perturbs the defect spin state and quenches the characteristic emission from the spin-quartet channel of V$ _\mathrm{Si}$ . Low-energy muon spin rotation further reveals that Ni contacts create a magnetically contaminated region extending at least $ \sim$ 120 nm into the SiC, in stark contrast to non-magnetic contacts such as Ti and Al. Moreover, cross-sectional cathodoluminescence measurements conducted on samples with box profiles of high defect density demonstrate a suppression of the quartet-state luminescence from the V$ _\mathrm{Si}$ over a distance up to 500 nm beneath the Ni contact. This drastic influence on the defect’s magnetic environment is accompanied by the appearance of a signature consistent with photoluminescence from the spin-doublet state of V$ _\mathrm{Si}$ in the vicinity of the Ni layer, which was not observed in other material stacks. These results establish that even standard device configurations can drive quantum defects into unwanted charge and spin configurations, underscoring the necessity of precise design to preserve quantum-grade spin environments in semiconductor devices.
Materials Science (cond-mat.mtrl-sci)
On the precise boundary of the Néel antiferromagnetic phase in the Shastry-Sutherland model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Rongyi Lv, Xiangjian Qian, Mingpu Qin
The ground state phase diagram of the Shastry-Sutherland model remains controversial. In particular, the nature of the transition between the plaquette valence bond solid (PVBS) phase and the Néel antiferromagnetic (AFM) phase is still under debate. While some studies suggest a direct transition between the two phases, others propose the existence of a narrow intermediate quantum spin liquid regime. To address this issue, we perform large-scale Density Matrix Renormalization Group calculations to determine the Néel AFM phase boundary in the Shastry-Sutherland model. By applying staggered boundary pinning fields and directly measuring the bulk staggered magnetization, and through systematic extrapolations with respect to truncation error as well as careful finite-size scaling, we find that the staggered magnetization remains finite across the controversial region $ 0.78 \lesssim J_{1}/J_{2} \leq 0.81$ , which was suggested to host a quantum spin liquid phase in some studies. Together with the previously established consensus placing the PVBS phase boundary at $ J_{1}/J_{2} \approx 0.78$ , these results provide evidence against the existence of an intermediate quantum spin liquid phase and support a direct PVBS–Néel AFM transition in the Shastry-Sutherland model.
Strongly Correlated Electrons (cond-mat.str-el)
Main text: 6 pages, 4 figures. Supplemental Materials: 9 pages, 9 figures
From Local Atomic Motifs to Thermodynamic State: An Interpretable Physics-Informed Framework for Cu-Zr Metallic Glasses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Machine-learning models that relate local atomic structure to the thermodynamic state of metallic glasses typically assess physical consistency after training rather than enforcing it during learning. Here, we develop a multi-task physics-informed neural network (PINN) that predicts temperature directly from Voronoi-motif population histograms while incorporating autograd-derived gradient constraints representing physically motivated relationships between structural motifs, quench rate, and temperature. The model simultaneously classifies each configuration as liquid, supercooled/transition, or glass through an auxiliary classification head. The classification task achieves 96.6% test accuracy with a macro-F1 score of 0.95, while the regression head yields a mean absolute error of 23.4 K on a trajectory-disjoint held-out test set. Five-fold trajectory-grouped cross-validation, deep-ensemble predictions, and Monte Carlo dropout are used to assess model robustness and predictive uncertainty. Sensitivity analyses demonstrate that physics constraints can be incorporated over a broad range of loss weights without compromising predictive accuracy, while substantially improving compliance with the prescribed physical trends. Benchmarking against conventional machine-learning regressors further demonstrates competitive predictive performance. SHAP analysis across the cross-validation ensemble identifies the coupled near-icosahedral motif family, particularly the full icosahedral motif and its single-atom-perturbed counterpart, as the dominant structural fingerprints of the glassy state. These results demonstrate that physically motivated constraints can be embedded directly into motif-based structure-property models, providing a pathway from post-hoc interpretability toward physically constrained machine learning for metallic glasses.
Materials Science (cond-mat.mtrl-sci)
31 pages, 11 figures
Apparent Breakdown of the Stress-Optic Rule in Rigid-Rod Suspensions: A Stress-Partitioning Interpretation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
William Kai Alexander Worby, Yuto Yokoyama, Misa Kawaguchi, Yoshiyuki Tagawa
A fundamental problem in the field of anisotropic macromolecular materials concerns how the flow-induced orientational order connects microscopic structure to macroscopic rheological stress and optical anisotropy. This study considered cellulose nanocrystal suspensions as rigid-rod model systems for the purpose of isolating orientational effects from chain stretching. Simultaneous rheo-optical measurements of birefringence, orientation angle, and shear stress were combined with a Fokker-Planck orientation model and stress decomposition. Our results show that, at low values of the Peclet number, birefringence and total stress exhibit proportionality similar to the stress-optic rule. However, the concentration dependence indicates that this proportionality reflects stress partitioning rather than a unique material coefficient. With increasing flow strength, orientational saturation is accompanied by a reduced relative Brownian stress contribution and a corresponding change in the total stress-based relation. Referencing the optical response to an estimated Brownian stress contribution yields a substantially more unified response across concentrations and flow conditions, supporting a stress-partitioning interpretation of apparent stress-optic rule breakdown.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
23 pages, 12 figures, 1 table
Non-Hermitian Topology from Edge Transport in Hermitian Quantum Anomalous Hall Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Humian Zhou, Ming Lu, Chui-Zhen Chen, X. C. Xie
Non-Hermitian physics, known for exotic phenomena like exceptional points and the skin effect, has been most prominently realized in engineered systems relying on controlled gain and loss. Here we show that it can also arise naturally as an intrinsic transport response of a globally Hermitian quantum anomalous Hall system, without the need for external non-Hermitian engineering. We show that the interplay between unidirectional chiral edge modes and diffusive normal edge modes induces intrinsic non-reciprocal transport described by a continuum Hatano-Nelson model. Consequently, the non-Hermitian skin effect is encoded directly in experimentally accessible Hall-bar observables: the electrochemical potential and local heat dissipation acquire chirality-dependent exponential spatial profiles, while the longitudinal conductance decays exponentially with system size and the Hall conductance remains quantized. Using Landauer–B{“u}ttiker simulations, we confirm these transport signatures and identify magnetic topological insulators as a realistic platform for an intrinsic non-Hermitian transport response. Our results bridge non-Hermitian topology with mesoscopic transport, opening a pathway toward non-Hermitian topological devices in solid-state systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
4 pages
Nature Communications (2026)
Magnetic Quadrupole Lens and Current-Induced Quadrupolar Dynamics of Antiskyrmion
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Linfeng Du, Yang Liu, Peng Yan, Ying Su
We demonstrate that antiskyrmions can serve as magnetic quadrupole lenses that focus or defocus electric currents traversing them. We showcase the antiskyrmion core as a focal point where electron beams converge for specific injection directions, leading to anisotropic and nonuniform current distributions. Thus the current-induced antiskyrmion dynamics is profoundly modified by the magnetic quadrupole lensing via the spin-transfer torque. By incorporating quantum transport and micromagnetic simulations iteratively, we self-consistently capture the coupled dynamics of conduction electrons and antiskyrmions. Our results unveil a quadrupolar antiskyrmion Hall effect that is highly anisotropic with respect to the current direction and can be effectively tuned by the spin-orbit coupling. In particular, the current focusing (defocusing) dramatically enhances (suppresses) the antiskyrmion speed while simultaneously reducing its Hall angle, thereby overcoming a key challenge for antiskyrmion racetrack memories. Our work establishes the intrinsic current lensing as a powerful mechanism for manipulating topological magnetic textures and opens new avenues for antiskyrmion-based spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures
Correlation-assisted spin-selective metallicity in strained and bilayer altermagnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Marnin J. Di Nunzio, Frank Lechermann, Ilya M. Eremin
Altermagnets combine vanishing net magnetization with a momentum-dependent spin-split electronic structure, providing a route to spin-polarized carriers without ferromagnetism. Here, we investigate how electronic correlations, doping, uniaxial strain, and interlayer coupling control altermagnetism within a minimal Hubbard-type model for mono- and bilayer systems. Comparing Hartree–Fock theory with the rotationally invariant slave-boson (RISB) approach, we demonstrate the robustness of altermagnetic order against quasiparticle renormalization and reveal a separation between the onset of magnetic order and the loss of quasiparticle coherence at stronger coupling. In the monolayer, doping produces a pronounced particle–hole asymmetry, while its combination with uniaxial strain generates a fully spin-polarized Fermi surface close to half-filling. In the bilayer, stacking that favors ferroic alignment of the layer altermagnetic order parameters allows their momentum-dependent spin splittings to combine constructively. Weak asymmetric doping additionally induces intra-unit-cell charge order, resulting in fully spin-polarized low-energy carriers. At a bilayer filling of five electrons in four orbitals, we find a continuous paramagnet-to-altermagnet transition followed, at stronger coupling, by an evolution toward a Mott-like regime with strongly suppressed quasiparticle weight. Our results establish correlations, strain, doping, and stacking as complementary means of controlling altermagnetic metals and generating fully spin-polarized Fermi surfaces.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
10 pages, 7 figures
An active soft glassy rheology model
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Raffaele Mendozza, Tobias Müller, Peter Sollich
Biological materials such as the cytoskeleton and confluent cell monolayers are active, dense systems continuously subjected to internal stresses and strains, making their rheological characterization essential. While activity in soft matter can be modeled across multiple length scales, its mechanical consequences remain strongly model dependent and no unified theoretical framework has yet emerged. Here, we study the rheology of dense active amorphous materials using the Soft Glassy Rheology (SGR) model, incorporating activity at the mesoscopic scale of local elements as a stochastic strain rate that is persistent on some timescale $ \tau_p$ . We show that activity opens a long-time relaxation channel, driving a crossover from SGR-like power-law rheology to Maxwell-like behavior at the lowest frequencies. Combining analytical arguments in limiting regimes with numerical simulations, we characterize the resulting fluidisation time scale and its dependence on the activity parameters, which shows strong analogies with effective temperatures introduced elsewhere that similarly encode activity-induced fluidisation. Our active SGR model provides a minimal mesoscopic route to understanding how driving by activity modifies the rheology of dense amorphous materials.
Soft Condensed Matter (cond-mat.soft)
9 pages, 4 figures
Collective depinning of dipolar skyrmion chains: thermal and athermal rounding of an elastic polymer in a quenched landscape
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
R. L. Silva, R. C. Silva, R. L. Stamps
The dynamics of interacting dipole skyrmion chains in a weak pinning landscape is studied through numerical solutions of the stochastic Thiele equation. Chains of different lengths with periodic boundary conditions are driven across quenched attractive pinning sites under different magnetic fields. A clear threshold spin current is identified as the critical depinning force. Three main results emerge: (i) for chains of 50 skyrmions or more, the depinning threshold is independent of chain length and remains close to one third of that of an isolated skyrmion. (ii) The transition rounding is only partly thermal: the width changes from w = 0.334 +/- 0.004 decades at T = 0 to 0.633 +/- 0.002 at 300 K, while the intrinsic Larkin correlation length remains about 2.6 bonds below kBT ~ V0/25. (iii) The width is nearly unchanged up to kBT ~ 0.14 V0, but increases almost fourfold by kBT ~ 0.23 V0, mainly through broadening of the creep regime. It is independent of chain length, ruling out finite-size rounding. Increasing the field from 30 to 40 mT changes the transition shape, widening its core by 26% while shortening the creep tails. For chains of about 200 skyrmions, depinning proceeds through a sequence of internal deformations - growth of the Larkin length and roughness, transient bond stretching, and subsequent recovery of mobility and Hall angle. These collective effects are relevant for skyrmion-based devices in which chains, rather than isolated textures, act as information carriers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
Bulk Superconductivity in Rocksalt LaN$_{1-x}$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Caeli Benyacko, Lin-Ding Yuan, Josiah A. Turner, Laila Reimanis, Siyuan Ji, Cheng Li, Erick A. Lawrence, Hanna Z. Porter, James M. Rondinelli, Stephen D. Wilson
We report the synthesis and characterization of lanthanum nitride by direct reaction of lanthanum metal with high pressure nitrogen gas in a laser floating-zone furnace. Combined synchrotron X-ray and neutron diffraction measurement verifies a rocksalt structure with stoichiometry LaN$ _{0.94}$ , consistent with first principles prediction that LaN is dynamically unstable in the stoichiometric limit. Electrical transport, heat capacity, and magnetization measurements show that LaN$ _{0.94}$ is metallic with a superconducting transition at $ T_c=5.95$ K. Our data establish LaN as the first bulk superconducting member of the rare earth mononitride family and motivates future exploration of the series using the unique processing space afforded by high-pressure optical reactors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
8 pages, 5 figures
Perspective: The HSE Screened Hybrid and the Band Gap Problem: Origins, Impact, and the Contenders
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
The ideas behind the screened hybrid functional HSE took shape in the early 2000s, about a quarter century ago. HSE was not explicitly designed to predict band gaps, although at the time we did recognize that hybrids could help address the band-gap problem. It was designed to make exact exchange affordable and physically defensible in extended systems. Keeping exact exchange at short range and screening it away at long range inverted the prescription developed for molecules. When HSE band gaps for ordinary semiconductors and selected metal oxides came out substantially closer to experiment than those obtained with conventional semilocal approximations, we were pleasantly surprised and encouraged by the path we had taken. The revision from HSE03 to HSE06 improved molecular thermochemistry while preserving the good accuracy for semiconductor gaps. The one-quarter exchange fraction was inherited unchanged from the successful unscreened PBE hybrid for molecules, rather than fitted to solids. HSE established a practical screened-hybrid approach for accurate band-gap calculations, expanding first-principles work in defect physics, photovoltaics, power electronics, and quantum information, among other areas. The first part of this Perspective recounts the decisions made at HSE’s birth and their influence on subsequent developments. The second part assesses recent advances in semilocal and hybrid functionals against benchmarks on sets of solids. Recent meta-GGAs achieve HSE06-level accuracy for selected semiconductors, while dielectric-dependent and tuned hybrids address the limitations of fixed screening. These hybrid developments share with our early work on local hybrids and local range separation the aim of adapting exact exchange to the electronic environment. The comparisons assess band gaps alongside structures, energetics, computational cost, and transferability.
Materials Science (cond-mat.mtrl-sci)
Tumor-induced lipid loss physically accelerates breast cancer invasion into mammary adipose tissue
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Garrett F. Beeghly, Dong Wang, Bo Ri Seo, Yitong Zheng, Joseph E. Druso, Benjamin D. Hopkins, Linda T. Vahdat, Neil M. Iyengar, Mark D. Shattuck, Corey S. O’Hern, Claudia Fischbach
Obesity is a major risk factor for breast cancer, yet how obesity-associated changes in the physical properties of white adipose tissue (WAT) influence tumor invasion remains poorly understood. Here, we combine experimental and computational approaches to investigate this question. Using mouse models and human mastectomy samples, we show that obesity not only increases adipocyte size, but also asphericity. We observe that tumor-conditioned media drives lipid loss and dedifferentiation of adipocytes into myofibroblast-like cells in vitro and that adipocytes in high-fat diet-fed mice lose lipid at a faster rate than those in normal diet-fed mice in response to mammary tumors in vivo. We then develop discrete element method (DEM) simulations to understand how these obesity-induced changes in cell and tissue properties alter breast cancer invasion under high-fat and normal diet conditions. In DEM simulations, adipocytes are modeled as deformable polygons and polyhedra, and cancer cells are modeled as soft, adhesive disks and spheres in two and three dimensions, respectively. Invasion is driven by cancer cell proliferation and tumor-induced lipid loss is modeled as corresponding decreases in adipocyte size. DEM simulations indicate that obesity-associated increases in tissue pressure induce adipocyte deformation, consistent with elevated asphericity in experimental data. At small lipid loss rates, the degree of cancer invasion is only weakly affected by tissue pressure. However, at sufficiently large lipid loss rates, we find that tissue pressure accelerates cancer invasion. Together, these results suggest that lipid loss physically remodels WAT to facilitate breast cancer invasion, and that obesity may exacerbate this effect.
Soft Condensed Matter (cond-mat.soft)
Trade-off between interface morphology and compositional homogeneity in AlGaAs/GaAs quantum wells revealed by multislice electron ptychography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Yiwei Ju, Han-Hsuan Wu, Amberly Ricks, Levi Brown, Moaz Waqar, Rithvik Ramesh, Xingxu Yan, Toshihiro Aoki, Seth R. Bank, Xiaoqing Pan
AlGaAs/GaAs asymmetric coupled quantum wells (ACQWs) are promising platforms for enhanced second-order optical nonlinearities, with their performance strongly influenced by the structural quality of heterostructures. Flat interfaces, together with high compositional homogeneity, are generally desirable for optimizing device functionality. Here we show that sharp and flat AlGaAs/GaAs interface morphology dominates the second harmonic generation (SHG) response in AlGaAs/GaAs ACQWs, even when significant compositional fluctuations in Al/Ga occupancy are present within the AlGaAs layers. Using multislice electron ptychography, we resolve the three-dimensional (3D) interface morphology and compositional distribution in AlGaAs/GaAs ACQWs under distinct growth interruptions. Longer growth interruptions sharpen and flatten the AlGaAs/GaAs interfaces, but at the same time cause stronger compositional fluctuations in the AlGaAs layers. These findings clarify how growth interruption tunes quantum wells structures and provide direct guidance for quantum wells design in next-generation optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
Non-Markovian Quantum Dynamics of Exciton-Polaritons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Rajanya Sarkar, Pritha Ghosh, Arshath Manjalingal, David R. Reichman, Arkajit Mandal
Exciton-polaritons, hybrid light-matter quasiparticles formed when a material interacts with a confined electric field, have experimentally been shown to exhibit mesoscale coherent quantum propagation that remains robust at room temperature. However, an accurate and direct quantum dynamical simulation of this phenomenon that does not resort to semi-classical approximations is prohibitively expensive computationally, limiting the microscopic understanding of the rich dynamical interplay among phonons, photons, and electrons under collective light-matter coupling. To address this fundamental challenge, we develop a non-Markovian master equation approach which enables the fully quantum mechanical simulation of non-equilibrium exciton-polariton dynamics and captures phonon-induced decoherence and dissipation beyond the conventional Markovian limit. To carry out this task, a procedure is developed in which the wave vector space is coarse-grained and each diagonal element of the density matrix is evolved in parallel. To demonstrate the utility of this approach, we simulate exciton-polariton transport in TIPS-pentacene. We find that our approach reasonably captures the experimentally observed renormalization of the polariton group velocity, which originates from the phonon-induced non-Markovian Lamb shift. We further show that this renormalization cannot be reproduced within conventional Markovian theories.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Long-range self-avoiding walk in one dimension: a Monte Carlo study
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Jiang Zhou, Ziyu Liu, Pengcheng Hou, Zhijie Fan, Youjin Deng
We study the one-dimensional long-range self-avoiding walk in the grand-canonical ensemble where the statistical weight of a jump of length $ r$ decays algebraically as $ r^{-(d+\sigma)}$ . Using large-scale Monte Carlo simulations with an efficient irreversible update scheme, we obtain high-precision estimates of the critical fugacity $ z_c$ , the universal Binder ratio $ Q_N^c$ , the correlation-length exponent $ \nu$ , and the anomalous dimension $ \eta$ . For $ \sigma>1$ , the critical fugacity varies smoothly with $ \sigma$ , while the Binder ratio and the critical exponents remain consistent with the short-range universality class. For $ \sigma \le 1$ , by contrast, the results clearly depart from short-range behavior, identifying $ \sigma=1$ as the boundary between long-range and short-range regimes. In the long-range Wilson-Fisher regime with $ 1/2 < \sigma \leq 1$ , $ \eta$ agrees with the long-range Gaussian-fixed-point prediction $ \eta_{\mathrm{GFP}}=2-\sigma$ , whereas $ Q_N^c$ and $ \nu$ vary nontrivially with $ \sigma$ and exhibit discontinuous jumps at $ \sigma=1$ . These findings are in good agreement with the recently proposed universality diagram in the $ (d,\sigma)$ plane for long-range O$ (n)$ models, with the self-avoiding walk corresponding to the $ n\to0$ limit.
Statistical Mechanics (cond-mat.stat-mech)
19 pages, 8 figures
Ultralow-Barrier Ion Transport in the Subnitride Electride Ba$_3$N for High-Rate Sodium Storage
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Electrides, ionic crystals in which excess electrons are delocalized within interstitial voids rather than bound to specific atomic sites, exhibit exotic physicochemical behaviors, yet their potential as electrochemical energy-storage hosts remains largely unexplored. Here, using comprehensive first-principles calculations, we demonstrate that the quasi-one-dimensional subnitride electride Ba$ _3$ N offers a compelling route to overcome the long-standing performance trade-offs in sodium-ion battery anodes. Spontaneous Na intercalation into the open interchain channels establishes thermodynamically stable phases, generating an exceptionally flat low-potential plateau that avoids the high-potential sloping losses of hard carbon while preserving an essential safety margin against dendrite formation. Crucially, the itinerant interstitial anionic electron sea dynamically flattens the potential landscape by suppressing site-specific orbital interactions, enabling ultrafast Na ion transport with an exceptionally low migration barrier. This work establishes a design paradigm for harnessing electride chemistry to achieve ultrafast battery electrodes.
Materials Science (cond-mat.mtrl-sci)
9 pages, 5 figures
Non-Hermitian Quantum Mechanics I: Instantaneous Self-Energy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Lingfeng Liu, Wei-Wei Yang, Jiangping Hu, Zhesen Yang
Starting from the unitary evolution of a closed quantum system, we rigorously demonstrate that the projection of the global wavefunction onto an arbitrary local subsystem is governed by an exact, time-dependent non-Hermitian Schrödinger equation. Crucially, the derivation does not rely on conventional approximations such as the Born approximation, the Markov approximation, or the wide-band limit. The central quantity is the \textit{instantaneous self-energy}, a time-dependent and generally non-Hermitian operator that encodes environmental backaction and, together with the subsystem Hamiltonian, forms the exact time-local generator of the projected dynamics. By benchmarking the conventional non-Hermitian approximation against this exact framework, we systematically expose its limitations. These results provide a rigorous microscopic foundation for the emergence of effective non-Hermitian dynamics in quantum systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages 3 figures
Sapphire-Side hBN Formation by Ni–Cr-Mediated Growth in a Stacked Ni–Cr/Boron/Sapphire Configuration: Effect of Boron Supply
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Donghoi Kim, Aelim Ha, Soohyung Park, Young Duck Kim, Chinkyo Kim
Metal-mediated growth provides an effective route to high-quality hexagonal boron nitride (hBN), but hBN formation on the metal does not necessarily ensure hBN formation on an adjoining dielectric substrate. Here, we investigate this distinction using a vertically stacked Ni–Cr/boron/sapphire configuration operated at 1550$ ^\circ$ C under atmospheric pressure, with the relative boron supply varied at fixed Ni:Cr = 8:2. hBN is detected by Raman spectroscopy on the gas-exposed alloy surface throughout the investigated Alloy:B range, whereas sapphire-side hBN appears only at the higher relative boron supplies of Alloy:B = 24:1 and 18:1, as confirmed by both Raman spectroscopy and XRD. The hBN (002) reflection further narrows as the boron supply increases from 24:1 to 18:1, corresponding to an increase in the apparent c-axis coherent length from approximately 86 to 143nm. Additional crystalline reflections also emerge only under these higher-boron conditions. These results identify boron supply as a key parameter governing the transition from alloy-side hBN formation to concurrent sapphire-side hBN growth. Once formed, sapphire-side hBN occurs within a substantially reconstructed and chemically modified Al/O-rich sapphire environment rather than as a uniform film on an intact substrate. To our knowledge, this study provides the first demonstration of successful sapphire-side hBN formation by Ni–Cr-mediated growth.
Materials Science (cond-mat.mtrl-sci)
Sub-Thermionic Switching in a Negative-Capacitance Bandgap-Change Field-Effect Transistor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Rahul B Awale, Mike Klymenko, Yuefeng Yin, Nikhil V Medhekar, Bhaskaran Muralidharan, Michael S Fuhrer
Overcoming the approximately 60mV/dec Boltzmann limit of the subthreshold swing remains a central challenge for low-power nanoelectronics. Negative-capacitance field-effect transistors address it by amplifying the channel potential, but their effectiveness is constrained by capacitance matching and by the quantum capacitance of conventional channels. Here we model a negative-capacitance bandgap-change field-effect transistor (NC-BCFET), in which the ferroelectric gate stack instead amplifies the electric field that opens the bandgap of the channel, using experimentally proven materials: bilayer graphene as a channel with an electrically tunable bandgap and Al$ _{0.55}$ Sc$ _{0.45}$ N as the negative-capacitance ferroelectric. Our self-consistent framework couples a four-band tight-binding Hamiltonian with GW-corrected screening, a quasistatic Landau–Devonshire ferroelectric response, and ballistic Landauer–Büttiker transport. Negative capacitance amplifies the interlayer potential difference, compressing the switching window 37-fold relative to a dielectric-gated control. At 300K, the optimized NC-BCFET achieves a subthreshold swing of 15mV/dec, four times below the Boltzmann limit, improving to 2.5mV/dec at 100~K. The room-temperature on/off ratio is limited to $ \sim 10^{2}$ by the bandgap of bilayer graphene. The concept extends directly to materials with larger field-tunable bandgaps, where deep subthermionic switching and high on/off ratios can be achieved together at room temperature.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
9 pages 4 figures. Also includes Supplementary Material with 5 figures
Critical Touching of Temporal Entanglement Transitions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Ting-Long Wang, Shi-Xin Zhang, Shuai Yin, Yi-Fan Jiang
Equilibrium phase transitions are conventionally categorized into first-order and continuous phase transitions. Far from equilibrium, many new transitions emerge during the real-time evolution of quantum systems. One such transition is the temporal entanglement transition (TET) characterized by the nonanalyticity of the entanglement spectrum. So far, all TETs occur through a linear crossing of the leading Schmidt levels in different symmetry sectors, resembling a first-order transition in equilibrium. A natural question is whether a continuous TET, featured by entanglement spectrum touching, is possible. In a periodically driven transverse $ J_1$ -$ J_2$ Ising chain, we show that two such TETs can merge into a critical touching, where the leading levels meet tangentially without exchanging, realizing the temporal analog of a continuous phase transition. Near the critical frequency, the temporal separation of the two TETs vanishes continuously and its derivative with respect to frequency diverges, a nonanalytic signature that is absent in a single first-order TET. This finite-frequency touching arises from the interplay between a weak symmetry-preserving perturbation of the product initial state and Floquet corrections. Further extending the frequency scan reveals a second critical touching at a higher frequency, and the two critical frequencies enclose a finite window with no TET. These features can be understood from a second-order Floquet Hamiltonian and persist across a broad range of coupling ratios, establishing the critical touching as a distinct form of TET.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
4.5 pages, 3 figures + supplemental material
Universal Generalized Brillouin Zone Theory I: Review of the Spectral Approach
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Zeqi xu, Jiangping Hu, Zhesen Yang
This series of papers aims to establish a universal generalized Brillouin zone (GBZ) theory for higher-dimensional non-Hermitian systems. As the starting point of this series, we emphasize a fundamental question: while the conventional one-dimensional (1D) GBZ condition, $ |\beta_p| = |\beta_{p+1}|$ , is well known to fail in two dimensions, how does this breakdown actually occur as a system gradually crosses over from 1D to 2D? Investigating this question reveals that the existing 1D GBZ theory itself remains incomplete. In this first paper, we therefore systematically review the 1D spectral approach and clarify where the underlying difficulties lie. Our work identifies the key challenges that motivate the wavefunction approach developed in Paper~II.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 10 figures
Rank-dependent optimal resetting in multiparticle search
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Ron Vatash, Eden Goldfarb, Vladimir Yu. Rudyak, Yael Roichman
In many soft-matter and biological systems, task completion relies on the cumulative arrival of multiple searchers rather than the speed of a single pioneer. The completion kinetics are therefore set not only by the first arrival, but by the full ordered sequence of first-passage times. Here, we determine how stochastic resetting optimizes these ordered arrivals for all arrival ranks. We construct an exact finite-$ N$ reference for non-interacting Brownian searchers and obtain the mean ordered first-passage time $ \langle T_{(k)} \rangle$ and its optimal resetting rate $ r_k^\ast$ . For searchers with identical initial conditions, $ r_k^\ast$ increases monotonically with arrival rank and, with increasing population size, approaches the known large-$ N$ quantile limit where a finite optimum appears only above a critical rank fraction $ \phi_c \simeq 0.412$ . Spatial heterogeneity qualitatively reorganizes this sequence, shifting its maximum from late to early ranks even without particle interactions. We then compare this baseline with Brownian colloid experiments, interacting active Brownian particles, and a collective autochemotactic search with persistent environmental memory. Across these systems, sensitivity to resetting increases strongly with arrival rank, while deviations from appropriate non-interacting references reveal the influence of direct interactions, finite return overhead, and environmental memory. Our results show that optimal resetting in multiparticle search is governed by the required completion rank and must be evaluated relative to protocol- and geometry-matched baselines.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Deterministic control of antiferromagnetic domain walls by circular phonons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Vladislav Bilyk, Nikolai Khokhlov, Viktoriia Radovskaia, Peter Kim, Pietro Diona, Ravi Kaushik, Luca Maranzana, Takeshi Hayashida, Sergey Artyukhin, Edwin Hang Tong Teo, Apoorva Chaturvedi, Carl S. Davies, Andrei Kirilyuk, Alexey Kimel, Dmytro Afanasiev
In an antiferromagnet, areas with different orientations of the antiferromagnetic Néel vector, which plays the role of the order parameter, can coexist, thus forming antiferromagnetic domains separated by domain walls. This suggests that antiferromagnets can possess the functionalities of magnetic storage media. Whether one can benefit from these functionalities crucially depends on the availability of efficient means for deterministic control of antiferromagnetic domain walls. Here, we demonstrate an approach to deterministically control domain walls in the van der Waals antiferromagnet Ni-doped $ MnPS_3$ via dynamic engineering of the crystal lattice. By resonantly exciting a pair of nearly degenerate orthogonal infrared-active $ A_u$ and $ B_u$ phonon modes with circularly polarized mid-infrared light, we induce helicity-dependent reconfiguration of 180° antiferromagnetic domains, providing evidence for a phonon-induced effective field conjugate to the Néel order parameter. The domain kinetics exhibit a pronounced helicity asymmetry governed by the interplay between domain-wall elasticity and defect-mediated pinning, enabling small phonon-driven perturbations to accumulate into stable domain transformations. Our results establish dynamic lattice control and defect engineering as means for deterministic control of antiferromagnetic order.
Materials Science (cond-mat.mtrl-sci)
Dual Role of Mobile Interstitials in Defect Kinetics: From Retardation to Acceleration
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Shihao Zhang (1), Shihao Zhu (1), Junping Du (1), Shuhei Shinzato (1), Ju Li (2), Shigenobu Ogata (1) ((1) The University of Osaka, Osaka, Japan, (2) Massachusetts Institute of Technology, Cambridge, USA)
Mobile interstitial atoms redistribute while defects migrate, complicating prediction of defect kinetics and leading to contradictory reports of acceleration and retardation. We formulate defect activation in a grand-canonical ensemble at fixed interstitial chemical potential and define a pathway free-energy landscape $ \Delta G(\Lambda;T,\mu)$ and the corresponding activation free energy $ \Delta G^{\ddagger}$ . We compute these quantities using both hyperplane-constrained thermodynamic integration via a mean force relation and a two-state chemical-potential integration, denoted TSCPI. The latter requires sampling only the initial and transition states; a single chemical-potential integration then yields $ \Delta G^{\ddagger}(T,\mu)$ across a wide $ \mu$ range, enabling rapid mapping over temperature and chemical potential. Applied to vacancy diffusion in FCC, BCC, and HCP metals with H (including in plane and cross plane diffusion in Zr) and in BCC W with He, both free energy routes agree with diffusion coefficients from molecular dynamics mean square displacements. The resulting maps reveal regimes of suppression and enhancement, including a crossover from suppression to enhancement with increasing hydrogen concentration. A site occupancy analysis links barrier shifts to state dependent site spectrum changes and transferable interstitial interaction terms.
Materials Science (cond-mat.mtrl-sci)
Multiscale Modeling of Ion Transport in Nanopores: Fitting Implicit-Water Radial Diffusion Profiles to Explicit-Water Molecular Dynamics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Mónika Valiskó, Salman Shabbir, Eszter Molnárné Lakics, Zoltán Ható, Dezső Boda
We develop a multiscale approach for incorporating molecular-scale transport information into computationally efficient models of ion transport through nanopores. A radially varying effective diffusion coefficient profile is fitted to radial conductivity profiles obtained from explicit-water molecular dynamics (MD) simulations. The fitting is performed within the NP+LEMC framework, which combines the Nernst–Planck equation with Local Equilibrium Monte Carlo to account for ion correlations beyond mean-field approximation. We apply the approach to NaCl, CaCl$ _2$ , and their mixtures in a negatively charged silica nanopore. The resulting diffusion coefficient profiles reproduce the radial current distributions of the MD simulations, including the strong suppression of ionic mobility near the pore wall that cannot be captured by a spatially constant diffusion coefficient inside the pore. NaCl and CaCl$ _2$ exhibit qualitatively different transport behavior: the former is cation selective due to enhanced near-wall Na$ ^+$ conduction, whereas the latter shows weak anion selectivity because strongly bound Ca$ ^{2+}$ ions have strongly suppressed mobility near the surface. For NaCl–CaCl$ _2$ mixtures, preferential Ca$ ^{2+}$ binding leads to nonlinear changes in ionic conductance. The approach establishes a bridge between experimentally relevant device behavior and computationally efficient reduced models, with explicit-water MD providing the molecular-scale information that can be incorporated into the effective transport coefficients.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
Uni-Macro-FRPN: Full-Resolution and Cross-Scale Learning for Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Jintao Wu, Yiran Shan, Rui Zhang
Polymer properties emerge from interactions across scales, yet existing polymer models typically preserve either detailed monomer chemistry without an explicit polymer graph or polymer connectivity with simplified monomer representations, due to computational constraints, as polymers typically contain tens of thousands of atoms. We present Uni-Macro-FRPN (FRPN), a Full-Resolution Polymer Network that retains both detailed atom-level and monomer-level features and explicit polymer structure information within a unified framework. Two Transformers jointly learn atom-informed monomer semantics, sequence order, and chain topology from BigSMILES-derived representations. On the Block Copolymer Database (BCDB) lamellar-versus-non-lamellar classification task, FRPN achieves 86.4% accuracy and 90.6% ROC-AUC, establishing state-of-the-art performance. Ablation results indicate that the gain is not explained solely by increased parameter count. On a linear homopolymer benchmark, monomer-centric learning remains competitive, highlighting a boundary case where polymer-scale organization is simple. To test generalization beyond linear polymers, we further construct an all-atom molecular-dynamics benchmark of 1640 datapoints spanning diverse monomer chemistries, sequence orderings, chain topologies, and physical properties. FRPN achieves the strongest overall performance on this topology-rich benchmark, with diagnostics supporting the benefit of jointly modeling monomer chemistry and polymer structure. Taken together, FRPN provides a practical route for moving polymer representation learning beyond monomer-centric representations. The leading performance of FRPN also suggests a promising direction for polymer informatics: future polymer prediction models should treat polymers not only as collections of monomer descriptors, but as complete multiscale chemical and topological objects.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Interplay of spin-orbit coupling and magnetic chirality: Multidirectional spin polarization in a helical antiferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Kallol Mondal, Sudin Ganguly, Santanu K. Maiti
We investigate spin-dependent transport in a non-collinear helical antiferromagnet in the presence of spin-orbit coupling within a tight-binding framework. Using the Landauer-Büttiker formalism, we analyze the generation of spin polarization arising from the combined effects of the helical magnetic texture and spin-orbit interaction. We find that finite spin polarization can be generated simultaneously along the $ \hat{x}$ , $ \hat{y}$ , and $ \hat{z}$ -directions, in contrast to the predominantly single-axis spin polarization commonly observed in conventional spin-filtering systems. The multidirectional spin polarization originates from the symmetry breaking introduced by the non-collinear magnetic order. We further show that the spin polarization is modified significantly in the presence of spin-orbit coupling and it has strong dependence on the parameters associated with the helical system. In particular, long-range hopping significantly enhances the spin-filtering effect, leading to large spin polarization components along all three spatial directions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
13 pages, 11 figures. Comments are welcome
Molecular dynamics simulations of DMSO-MeOH liquid mixtures. Effects of force fields on mixing properties
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
We explore composition dependence of the principal properties of liquid dimethylsulfoxide (DMSO)-methanol (MeOH) liquid mixtures by using molecular dynamics computer simulations. A set of non-polarizable semi-flexible models for the DMSO molecule combined with methanol models is investigated. Composition trends of density, excess mixing volume and excess mixing enthalpy are evaluated. Besides, we study the composition dependence of self-diffusion of species and shear viscosity ofthe static dielectric constant and the surface this http URL aspects of the microscopic structure are analyzedin terms of radial distribution functions and of the average number of hydrogen-bonded molecules. The quality of several combinations of the models is illustrated and critically evaluated by comparisons with experimental data.
Soft Condensed Matter (cond-mat.soft)
17 pages, 13 figures
Phase field modelling of microstructure transformations in Zr-Sn alloy during irradiation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
V. O. Kharchenko, D. O. Kharchenko, A. V. Dvornichenko
In this work we study peculiarities of spatial rearrangement of solute and vacancy concentrations in Zr-Sn alloy at stages of both thermal treatment of solid solution and irradiation of annealed alloy under reactor conditions. To this end, we exploit phase field modelling including reaction rate theory and CALPHAD method combined in one generalized approach. Simulations were done in 3D in order to get a detailed information about rearrangement of solutes and defects in a bulk. We discuss the emergence of the secondary phase at the stage of thermal treatment and its stability under neutron irradiation. We analyze an influence of the irradiation dose onto statistical properties of the secondary phase particles.
Materials Science (cond-mat.mtrl-sci)
15 pages, 10 figures
The effect of homopolymer adding on aggregation behavior in amphiphilic triblock copolymers containing rigid blocks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
X.-G. Han, H. Zhang, Z. H. Sun, M. Y. Zhu
The effect of B homopolymer adding on the aggregation behavior of amphiphilic coil/rod/coil BAB triblock copolymers was studied using lattice self-consistent field theory. It depends on the length of the hydrophobic rod block and copolymer concentration. Compared with the solutions, at low concentrations, homopolymer addition is favorable to the emergence of cubic and large lamellar micelles. Although it enriches the structural behavior, the rearrangement is suppressed. As rod blocks increase, the rearrangement is related to the orientation-dependent diffusion and inverse diffusion processes. At relatively high concentrations, adding homopolymers promotes rearrangement. For long rod block case, the arrangements related to inverse laminarization and the cooperative growth emerges. At high concentrations, for short rod block system, homopolymer addition is advantageous to micelle rearrangement concerned with order/disorder transition, and the rearrangements in the system of intermediate length and long rod blocks are suppressed. This work aids in understanding of the growth mechanism of micelles with rigid block cores.
Soft Condensed Matter (cond-mat.soft)
12 pages, 11 figures
The ferromagnetic diatomic molecules with the mixed spin-1/2 and spin-1
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Diatomic molecules consisting of one spin-1/2 ($ \sigma$ ) and one spin-1 ($ S$ ) atom are put at each site of the Bethe lattice (BL) of the coordination number $ q=3, 4$ , or 6. Alongside the ferromagnetic (FM) interactions of individual atoms within a molecule, the molecules are permitted to engage in ferromagnetic interactions with their nearest neighbors (NN) through diverse bilinear interaction parameters $ J$ . The spin-1 sites are also under the influence of crystal field $ D$ . The phase diagrams on the ($ D, T$ ) planes for a given $ q$ are obtained by investigating the thermal variations of magnetizations for the case with zero external magnetic field $ (H)$ . It is discovered that the phase diagrams rely on $ q$ both qualitatively and quantitatively. The crystal field is also included which operates only on the spin-1 sites. Three separate FM phases are observed with ($ \sigma,S$ ) being $ (1/2,1), (1/2,0)$ at the ground state level and a phase region with small magnetization (SM) values at a higher temperature range. In addition to the reentrant behavior in the transition zone from one phase to the other, the model produces first- and second-order phase transitions. Additionally, the impact of $ H$ on the magnetization curves is examined, yielding quite intriguing findings.
Statistical Mechanics (cond-mat.stat-mech)
11 pages, 6 figures
Tailoring structural, electronic, optical, and magnetic properties of rare-earth gallates RGaO$_3$ (R = Ho, Er, Tm) via first-principles investigations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
T. Usman, K. Liaqat, S. Khan, M. Yar Khan, S. Ali Khan
Ab initio calculations of cubic perovskites RGaO$ _3$ (R = Ho, Er, Tm) were performed using the full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT). We investigated their structural, electronic, magnetic, and optical properties in detail. In the optimized configurations, the lattice constants ranged from 3.83 to 3.85 A. The electronic band structures indicate that ErGaO$ _3$ is semiconducting, whereas HoGaO$ _3$ and TmGaO$ _3$ exhibit half-metallic behavior, probably due to the interaction of spin-orbit coupling with the electronic states near the Fermi level. Optical response of half-metallic compounds (HoGaO$ _3$ ,TmGaO$ _3$ ) is strongly governed by their spin polarization electronic structure. The semiconducting spin channel absorbs ultraviolet photons, while metallic or small gap channel interacts with infrared light. This dual behavior enables spin selective optical excitation, relevant for spintronics and optoelectronics applications. These compounds show high surface reflectivity, with TmGaO$ _3$ achieving a maximum reflectivity of 69%. Moreover, their optical conductivity mainly occurs at higher energies, indicating suitability for high-energy optoelectronic applications. The calculated magnetic moments suggest a robust ferromagnetic character across this series.
Materials Science (cond-mat.mtrl-sci)
14 pages, 4 figures
Computational investigation of a perovskite LaBiO$_{3}$ for photovoltaic, thermoelectric, and optoelectronic applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
M. M. Woldemariam, N. G. Debelo, T. K. Tufa, E. M. Gurmesa, S. H. Didu, S. N. Asfaw, D. T. Keno
Using density functional theory (DFT) with the ONCVVPSP pseudopotential and PBE functional, this study investigates the structural, electronic, elastic, optical, and thermoelectric properties of the trigonal LaBiO$ _{3}$ perovskite oxide (space group R3c). Ground-state parameters lattice constant, volume, bulk modulus, and its pressure derivative were determined using the equation of state. Applying the Hubbard correction (GGA+U) revealed an indirect, wide band gap of 3.51 eV. Mechanical properties, including the anisotropy factor, elastic modulus, and Poisson’s ratio, were calculated via the Voigt-Reuss-Hill averaging scheme. The bulk-to-shear modulus ratio identifies the trigonal phase as ductile. Additionally, Debye temperatures and sound velocities were computed. Optical characteristics (absorption coefficient, refractive index, and electron energy loss function) were evaluated across a 0-35 eV spectral range. Finally, semi-classical transport coefficients, including electrical conductivity, Seebeck coefficient, and power factor, were calculated to assess the material’s thermoelectric potential.
Materials Science (cond-mat.mtrl-sci)
14 pages, 9 figures
Electronic energy structure and optical properties of In${4}$CdI${6}$ from $\textit{ab initio}$ calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
I. V. Semkiv, N. T. Pokladok, F. O. Ivashchyshyn, A. I. Kashuba
This work presents the $ \textit{ab initio}$ calculations of the electronic energy spectrum of the In$ {4}$ CdI$ {6}$ compound. The study was conducted within the framework of density functional theory (DFT), using local density approximation (LDA) and general gradient approximation (GGA) pseudopotentials, and the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. The GGA approximation was implemented using the PBE and PBEsol exchange-correlation functional. Based on the electronic energy structure, the type of the minimum band gap was determined, and an analysis of the energy level dispersion for both the valence and conduction bands was performed. Furthermore, the effective masses of electrons ($ \textit{m}{c}$ ) and holes ($ \textit{m}{v}$ ) for In$ _{4}$ CdI$ _{6}$ were established. The energy band analysis was complemented by the calculation of the density of states (DOS). Based on the electronic energy spectrum, the real and imaginary components of the dielectric function are calculated. Using the Kramers-Kronig relations, we also derive such fundamental optical functions of In$ _{4}$ CdI$ _{6}$ as the refractive index $ \textit{n}$ , and the extinction coefficient $ \textit{k}$ .
Materials Science (cond-mat.mtrl-sci)
10 pages, 5 figures
Hund-driven local-itinerant duality of Eu-4$f$ electrons in infinite-layer nickelates
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Recent discovery of reentrant superconductivity and elevated $ T_c$ in Eu-substituted infinite-layer nickelates raises a critical question concerning the nature of Eu-4$ f$ states and their potential interaction with Ni-$ d$ electrons. Here we combine density functional theory with the dynamical mean-field theory (DFT+DMFT) calculations to investigate the valence and magnetic properties of Eu-ions in the nickelate 112 structure, explicitly treating the Coulomb repulsion in both Ni-3$ d$ and Eu-4$ f$ shells. We find a three-regime evolution of the Eu-4$ f$ configuration driven by its Hund’s rule coupling $ J_{\rm H}$ . The magnetic and mixed-valence Eu ionic state inferred by experiments only occurs for moderate $ J_{\rm H}$ , with coexisting local moments and strongly correlated $ j=7/2$ quasiparticles, in contrast to the nonmagnetic state at small $ J_{\rm H}$ and the fully spin-polarized divalent state at large $ J_{\rm H}$ . This local-itinerant duality arises from an effectively hole-doped orbital-selective Mott state induced by the intra-4$ f$ charge transfer between $ j=5/2$ and $ 7/2$ manifolds. It not only explains the origin of the mixed-valence and local moment behaviors of the Eu-ions observed experimentally, but also predicts low-energy 4$ f$ quasiparticles that may hybridize with the Ni-3$ d$ electrons and contribute to the elevated $ T_c$ . Our work provides a basis for understanding the unusual ferromagnetic and superconducting properties of Eu-substituted infinite-layer nickelates.
Strongly Correlated Electrons (cond-mat.str-el)
Competition between uniform ferromagnetism and finite-wave-vector instabilities in square-lattice skyrmion crystals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
We investigate square-lattice skyrmion crystal states in a centrosymmetric spin model with momentum-dependent magnetic interactions, including a uniform ferromagnetic interaction, easy-axis anisotropic interactions at two orthogonal finite wave vectors, higher-harmonic wave-vector interactions, and an external magnetic field. Using simulated annealing calculations, we determine the low-temperature magnetic phase diagram as functions of magnetic field and uniform ferromagnetic interaction strength. We find that the skyrmion crystal phase is stabilized at intermediate fields when the uniform ferromagnetic interaction is weak, exhibiting a noncoplanar double-$ Q$ spin texture, finite scalar spin chirality, and higher-harmonic components. Increasing the uniform ferromagnetic interaction suppresses and eventually eliminates the skyrmion crystal phase through direct first-order transitions to the fully polarized state, whereas its weakening expands the skyrmion stability region and stabilizes a single-$ Q$ conical spiral phase at high fields. These results clarify the mechanisms governing the square-lattice skyrmion formation in centrosymmetric magnets.
Soft Condensed Matter (cond-mat.soft)
19 pages, 10 figures
Light absorption and scattering of an assembly of spheroidal metal nanoparticles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
N. I. Pavlyshche, A. V. Korotun, V. P. Kurbatsky
The paper studies the optical properties of assemblies of metallic prolate and oblate nanospheroids. The frequency dependences of averaged absorption and scattering cross-sections, absorption, scattering and reflection coefficients are obtained. The calculations were performed for assemblies of spheroidal particles of various metals. The difference in the results of calculating the frequency characteristics of the absorption and scattering cross-sections for assemblies of prolate and oblate spheroids manifested itself in different location and value of the maxima. A qualitative similarity of the frequency dependences of the absorption and scattering coefficients was established. It is shown that the frequency curves of assemblies of spheroids of different metals differ significantly in the location of the extrema within the range from the visible to the ultraviolet region of the spectrum
Soft Condensed Matter (cond-mat.soft)
12 pages, 7 figures
Electronic structure and anisotropic magnetotransport in the topological kagome ferromagnet MgMn6Sn6
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Debasmita Swain, Mohit Mudgal Suman Nandi, Aradhana Kumari, Yogendra Kumar, Vivek Kumar Malik, Anup Pradhan Sakhya, Masahiro Sawada, Shin-ichiro Ideta, Kenya Shimada, Jayita Nayak
We report the magnetic, magnetotransport, and electronic properties of the kagome ferromag net MgMn6Sn6 using magnetization, angle dependent magnetoresistance, x-ray magnetic circular dichroism (XMCD), angle resolved photoemission spectroscopy (ARPES), and first-principles cal culations. MgMn6Sn6 exhibits ferromagnetic ordering near TC=295 K with pronounced easy plane magnetic anisotropy. At low temperatures and low magnetic fields, the magnetoresistance (MR) is strongly anisotropic with respect to the magnetic field orientation, evolving from a predominantly negative MR for in-plane fields to a more quadratic behavior for out-of-plane fields. Angle depen dent measurements further reveal a pronounced twofold MR anisotropy with additional higher order contributions. The finite orbital-to-spin moment ratio revealed by XMCD suggests a significant role of spin-orbit coupling (SOC) in MgMn6Sn6. The first-principles calculations show a Dirac-like band crossing at the K point and a van Hove singularity (VHS) at the M point, as expected for kagome materials. ARPES measurements resolve a sixfold symmetric Fermi surface and its systematic evo lution with binding energy, in overall agreement with first-principles calculations. The measured band dispersions are also broadly consistent with the calculated multiband electronic structure. These results establish the connection between magnetic anisotropy, anisotropic magnetotransport, and the kagome derived electronic structure of MgMn6Sn6.
Strongly Correlated Electrons (cond-mat.str-el)
A small-distortion geometric model for elasto-plasticity in single crystals driven by the motion of dislocations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
A central problem in nonlinear elasto-plasticity theory is to formulate a geometrically nonlinear, large-strain model of elasto-plasticity in single crystals in which plastic flow is driven directly by the motion of dislocations and which allows for a homogenization procedure from discrete dislocation lines to dislocation densities. In this work, such a model is introduced based on two hypotheses: (1) The Small-Distortion Hypothesis posits that the total plastic distortion may be arbitrarily large but its dominant part admits a representation as a gradient, meaning that the distorting effect of dislocations is small relative to the specimen size. Concretely, this hypothesis is realized here through a “multiplicative Helmholtz-type decomposition”, which splits an arbitrary matrix field into the product of a gradient and a matrix field with controlled curl. (2) The Line-Tension Approximation treats all dislocations as infinitesimally thin lines whose local stress fields are individually negligible compared to specimen-scale stresses and only matter in the aggregate. The resulting model, termed the Small-Distortion Geometric Model, furthermore employs the so-called Space-Time Framework, which furnishes a geometric language to precisely describe the advection of dislocation lines. As such, it provides a physically grounded account of crystal plasticity in an idealized mesoscopic setting that bridges dislocation mechanics and continuum elasto-plasticity.
Materials Science (cond-mat.mtrl-sci)
71 pages
Experimentally validated process-microstructure-property relations of bainitic steels derived from phase-field simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Dhanunjaya Kumar Nerella, Muhammad Adil Ali, Oguz Gulbay, Oleg Shchyglo, Ingo Steinbach
This study examines the impact of processing conditions, such as thermalprocessing, on the resulting microstructure and mechanical properties. Spe-cial emphasis is placed on microstructural features obtained from three-dimensional phase-field simulations, which provide detailed insights into bai-nite morphology, phase distribution and retained austenite content. Thesesimulated microstructures are correlated with changes in yield strength undermultiaxial load, as represented in the yield surface of the material. The re-sults demonstrate that optimized processing routes can refine the microstruc-ture, enhance mechanical properties and significantly alter the yield surfacecharacteristics. These findings provide valuable insights for the design andapplication of bainitic steels, as well as for the development of predictivemodels linking process-structure-property relationships.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Matching Rules for a Three-Dimensional Strongly Aperiodic Monotile
New Submission | Other Condensed Matter (cond-mat.other) | 2026-09-22 20:00 EDT
A recent pre-print [arXiv:2609.19214] proposed a three-dimensional (3D) strongly aperiodic monotile: a shape that tiles Euclidean space only aperiodically and which admits no symmetry of infinite order. The proof takes the 3D Chair tile identified previously by Lee and Moody, and adds geometric decorations to the faces so as to force aperiodicity (without these decorations The Chair also admits periodic tilings). Here we establish general requirements on face decorations to achieve the same end, in order to facilitate the search for physical realisations. We find that the requirements are minimal. We provide matching rules using three colours of arrow. They are not equivalent to the original rules, but force the same tiling by forcing Chairs to compose into `Superchairs’ with doubled linear dimensions. In this process the matching rules themselves compose uniquely, which is the core of the earlier proof. Relaxing this constraint further we find that the same structure can be forced using only a matching rule based on the colours of squares, regardless of orientation. Any physical system encoding these rules (geometrically or otherwise) will force the strongly aperiodic monotiling. We provide simple examples.
Other Condensed Matter (cond-mat.other), Mathematical Physics (math-ph)
5 pages, 4 figures
Robust Spin Universality Across a Ballistic-to-Diffusive Transport Crossover
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-22 20:00 EDT
Cătălin Paşcu Moca, Ovidiu I. Pâţu, Balázs Dóra
Whether a full counting statistical distribution preserves its universality class across a coherent-to-incoherent crossover is a fundamental question in open quantum systems. We resolve this for the infinite-$ U$ Hubbard chain, showing that local density dephasing changes transport exponents without destroying the underlying non-Gaussian M-Wright spin fluctuations. Utilizing the exact spin-charge composition law inherent to impenetrable dynamics, we track the charge sector from ballistic flow to diffusive hydrodynamics. This dissipative crossover shifts the characteristic spin-transfer width from $ t^{1/4}$ to $ t^{1/8}$ . Despite this altered scaling time, the central spin characteristic functions uniformly collapse onto a singular M-Wright scaling function, what we confirm using analytics as well as numerics.
Quantum Gases (cond-mat.quant-gas)
5 pages, 5 figures
THz Spectroscopy of Urine Vapors from Patients with Prostate Cancer and Benign Prostatic Hyperplasia: A Pilot Analysis
New Submission | Other Condensed Matter (cond-mat.other) | 2026-09-22 20:00 EDT
V. A. Atduev, A. V. Maslennikova, V. L. Vaks, E. G. Domracheva, M. B. Chernyaeva, V. A. Anfertev, K. A. Atduev, Y. Tawalbeh, M. F. Pereira
Approximately 13% of men will be diagnosed with prostate cancer (PC) during their lifetime. Serum prostate-specific antigen (PSA) is widely used for screening and risk assessment; however, PSA elevations are not cancer-specific and may also occur in benign conditions such as prostatitis and benign prostatic hyperplasia (BPH). Additional non-invasive approaches capable of provid- ing complementary molecular information are therefore needed. Here, we present an exploratory pilot study using high-resolution terahertz (THz) spectroscopy to examine urine-derived volatile and thermal-decomposition products. Analysis of urine samples from 24 patients with PC and 14 patients with BPH identified differences in the reported molecular-assignment patterns and candi- date spectral features for further evaluation. The study was designed for candidate identification and feasibility assessment and did not evaluate diagnostic accuracy or superiority to PSA. These findings support further investigation of THz spectroscopy as a potential source of complementary molecular information alongside PSA and other established clinical assessments. The study also outlines the technical standardization and clinical-validation requirements that must be addressed before this approach can be considered for routine clinical use.
Other Condensed Matter (cond-mat.other), Quantitative Methods (q-bio.QM)
A Spatio-Temporal Generalisation of Green Kubo
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
E. R. Smith, D. Dini, D.M. Heyes
The Green-Kubo (GK) method which is used to obtain the shear viscosity of a model liquid in equilibrium molecular dynamics (MD) often requires long simulation times to obtain acceptable statistics. This work extends the GK approach to include spatial correlations. The total shear stress in the GK expression is split into a grid of its components in contiguous volumes. In doing this, the autocorrelation of the total system stress can be rewritten as the cross-correlation of the subvolume stresses. This provides a novel real-space insight into the liquid structure, something previously only treated in Fourier space by liquid-state theory. A novel travelling wave like structure is exposed that is shown to be well fitted by a leading Gaussian pulse added to a second negative Gaussian for the bounce back. The fitting parameters include the wave position, magnitude and width which show deep insights into the liquid property. The wave moves at the speed of sound over short times before decreasing in speed with the square root of time, while the wave packet spreads out also as the square root of time. The magnitude is decreasing with form $ t^{-3/2}$ , a result with strong significance in the history of MD simulation. These fitted forms mean the entire spatial temporal response of the liquid can be modelled in closed form by fitting to data, with short term requiring MD and the long time and distances approximated by the Gaussian form. By limiting the correlation to localized interactions the longer range contribution, which essentially only contribute to the noise, can be eliminated. This looks like a promising approach to model viscosity by taking short MD runs and fitting the long time behaviour.
Statistical Mechanics (cond-mat.stat-mech)
41 pages (double spaced), 14 Figures, pre-final checks draft
Transitions between bulk and interfacial fracture in diamond/$c$BN heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Wei Qiu, Feiyu Zhou, Xiaonan Wang, Feng Xie, Yan Chen, Shengying Yue, Yilun Liu, Penghua Ying
Whether an initially crack-free heterostructure fails at its interface or within an adjoining phase is controlled by the relative cohesion of competing atomic planes, but how interfacial chemistry, crystallographic orientation, and intermixing reshape this competition remains unclear. Here, we combine density functional theory (DFT) with a fine-tuned atomistic foundation model to resolve tensile fracture in coherent diamond/cubic boron nitride (cBN) heterostructures. The resulting potential reproduces independent DFT tensile responses, including an unseen (001) interface orientation. Interfacial termination, orientation, and diffusion-induced intermixing jointly determine fracture resistance and fracture-plane selection. C-N-bonded (111) and C-B-bonded (001) remain interface-controlled throughout the investigated intermixing range, whereas pristine C-B-bonded (111) fractures at a neighboring B-N plane inside cBN because the interface is more strongly bound. Increasing the diffusion fraction from 0 to 50.0% causes a nonlinear decrease in fracture strength from 50.3 to 15.8 GPa and drives a bulk-to-interface transition through three regimes: cBN fracture up to 4.86%, configuration-dependent competition between 7.6 and 10.1%, and interfacial fracture at 12.5% and above. Atom-resolved stress fields and DFT separation energetics show that this transition is associated with stress relocation and a reversal in the relative cohesion of competing planes, while electron localization analysis connects the cohesion hierarchy to termination- and orientation-dependent bonding. These results establish an atomistic framework for controlling fracture resistance and fracture pathways in strongly bonded heterostructures.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
16 pages, 10 figures
Decoupling the Magnetic Field Operator as an Independent Operator Class in Stochastic Series Expansion Quantum Monte Carlo
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
The Stochastic Series Expansion (SSE) quantum Monte Carlo method with loop updates is among the most powerful approaches for quantum spin and boson systems. In the standard formulation, the magnetic field term is routinely absorbed into the Heisenberg interactions—a strategy that has proven highly efficient across a wide range of field strengths. In this work, we propose a more general SSE framework in which the magnetic field operator is treated as an independent operator class, enabling it to participate in Monte Carlo updates on an equal footing with all other operators. Importantly, the field operator and other interaction operators can transform into one another during the update process. We demonstrate this algorithm using the two-dimensional antiferromagnetic Heisenberg model in a magnetic field as a concrete example. The simulation results agree with those of the conventional algorithm, confirming the correctness of the new formulation. A comparison of the integrated autocorrelation time shows that the new algorithm is competitive. This flexibility not only facilitates measurements of observables associated with operators but also offers potential computational advantages for a broader class of problems.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 6 figures
A Majorana Formulation of Time-Dependent Two-Particle Reduced-Density-Matrix Dynamics
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Haoran Wang, Alessandro Principi
We introduce a time-dependent two-particle (TP) reduced-density-matrix algorithm for systems of interacting Majorana fermions. We close the BBGKY hierarchy at the two-particle level by reconstructing the three-particle reduced density matrix from lower-order correlations. To stabilize the evolution, we impose a positivity projection on the two-particle density matrix while preserving chosen conserved quantities such as the energy. We benchmark the approach on quenches in the one-dimensional Hubbard model and on flux dynamics in the Kitaev honeycomb model. For the Hubbard quench, TP captures strong-coupling dynamics missed by Hartree–Fock (HF). For the Kitaev quenches, TP accurately reproduces the early-time flux dynamics in several regimes and provides a substantial improvement over HF when two-particle correlations are important. We further show that gauge coherence is essential for flux dynamics. The projection procedure however introduces an effective irreversibility, which affects the long-time dynamics.
Strongly Correlated Electrons (cond-mat.str-el)
Scalable Multiple Electron Transport Architectures for Feedback Traceable Current Sources
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Agustin Javier Lapi, Guillermo Fernandez Moroni, Fernando Chierchie, Fabricio Alcalde Bessia, Miqueas Ezequiel Gamero, Brenda Aurea Cervantes Vergara, Blas Junior Irigoyen Gimenez, Eduardo Paolini, Claudio Rodrigo Chavez Blanco, Juan Estrada, Javier Tiffenberg
We present a scalable electron-counting current cell based on a floating gate architecture operated as a Multiple Electron Transport device (MET). The system enables controlled injection, transport, and precise quantification of discrete charge packets using the sensor non-destructive multiple readout capability. We repurposed the charge-injection technique, jointly with the electron-resolution capability, for a controlled generation of quantized charge packets for an electron-traceable current source.
Scalable architectures based on parallel and series multi-amplifier configurations are explored. Experimental results confirm noise reduction following the square root of the number of independent measurements and demonstrate stable, programmable output current. This approach provides a compact and scalable platform for electron-counting current sources and precision quantum metrology applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Instrumentation and Detectors (physics.ins-det)
12 pages, 19 figures
Carrier duality from the convergence of Dirac fermions and high-order van Hove singularities
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Meng Lyu, Kaiyi Zhai, Nikolai Peshcherenko, Junyan Liu, Jinying Yang, Subir Sen, Binbin Wang, Langsheng Ling, Zhaosheng Wang, Gang Li, Jieyi Liu, Yang Xu, Xiyang Li, Claudia Felser, Yang Zhang, Wujun Shi, Lexian Yang, Enke Liu
The convergence of highly mobile Dirac fermions and flat-band heavy electrons offers a paradigm for emergent quantum phenomena. However, experimental realization of such intriguing state remains elusive. In this study, we report a dual carrier regime in the kagome metal Co3In2S2, wherein the charge transport is governed by high-mobility electrons while the thermodynamic responses exhibit heavy-electron behavior. This exotic duality arises from the coexistence of topological Dirac fermions and flat-band high-order (4th-order) Van Hove singularities (HOVHSs) at the Fermi surface, as revealed by magnetic-torque quantum oscillation and angle-resolved photoemission spectroscopy. The interaction between Dirac and HOVHS-derived carriers can be captured by a minimal two-pocket model, manifesting as sublinear resistivity above ~100 K and field-induced non-Fermi-liquid behavior at low temperatures. Our study establishes Co3In2S2 as a model platform for exploring many-body physics at the intersection of topology and correlation effects, and provides a foundational framework for designing quantum materials hosting diverse emergent states.
Strongly Correlated Electrons (cond-mat.str-el)
27 pages, 5 figs
Exact Nonperturbative Equilibrium Mode Statistics in Nonlinear Wave and Lattice Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Jialin Zhang, Yong Zhang, Hong Zhao
We derive exact finite-size nonperturbative representations of equilibrium modal occupations and related statistics for three representative nonlinear systems: the Majda-McLaughlin-Tabak dispersive-wave model, the Fermi-Pasta-Ulam-Tsingou beta anharmonic chain, and the discrete nonlinear Schrodinger lattice field. Independent simulations confirm the predictions from weak to strong nonlinearity. For DNLS, the theory remains accurate across the weak-coupling quasicondensation crossover, where large low-mode occupations and long-range coherence amplify interaction effects even when the bare nonlinear coefficient is small. The finite-ring DNLS occupations are further resolved into a positive sum of Rayleigh-Jeans channels with distinct correlation lengths, explaining when a single Rayleigh-Jeans law applies and why it fails near quasicondensation. In MMT and DNLS, the exact occupations also determine the mean modal frequencies even when the dynamical spectra broaden or split. The nonperturbative results allow a direct assessment of two representative perturbative approaches. Treating the mean interaction appropriately yields accurate low-order approximations, including at strong nonlinearity. At higher orders, however, the corrections cease to decrease and successive approximations oscillate with increasing amplitude; both finite-order approaches also fail near weak-coupling quasicondensation. Thus neither low-order agreement nor a small bare coupling guarantees a reliable perturbative description. The results establish nonperturbative equilibrium theory for widely used nonlinear wave and lattice models and provide a quantitative basis for modal distributions of energy, particles, and optical power in nonlinear optics, dispersive waves, anharmonic lattices, and cold-atom systems.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Mathematical Physics (math-ph), Applied Physics (physics.app-ph)
47 pages, 15 figures
Enhanced thermal conductivity of (010) (AlxGa1-x)2O3 epitaxial films utilizing indium-catalyzed molecular beam epitaxy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Shivashree Gowda, Stephen Schaefer, Ethan A. Scott, Samreen Khan, Patrick E. Hopkins, M. Brooks Tellekamp
(AlxGa1-x)2O3/beta-Ga2O3 transistors are an emerging candidate for high-power and high-frequency electronic devices. beta-Ga2O3 in particular is notably limited for anisotropic low thermal conductivity, which is further reduced in (AlxGa1-x)2O3 due to alloy and other defect-driven phonon scattering mechanisms. In this work we show that the thermal conductivity of (010) oriented (AlxGa1-x)2O3 thin films for 0.01 < x < 0.20, measured using time-domain thermoreflectance (TDTR), is limited by alloy scattering without observable adverse scattering by additional defects. This is enabled through the synthesis of the (AlxGa1-x)2O3 films using molecular beam epitaxy (MBE) on \b{eta}-Ga2O3 substrates, leveraging indium-catalyzed growth to suppress dislocation formation and phase separation to achieve single-phase pseudomorphic films up to x = 0.2. This growth process improved the thermal conductivity of (AlxGa1-x)2O3 by 2X as compared to previously reported values. For increasing Al composition (x), we observe a steady decline in (AlxGa1-x)2O3 thermal conductivity due to alloy scattering which is validated using virtual crystal approximation (VCA) model. We also show that the thermal boundary conductance across the Al/(AlxGa1-x)2O3 interface is reduced with increasing x, which we posit is due to the stiffening of the (AlxGa1-x)2O3 acoustic modes with increasing x by comparing experimental results with a diffuse mismatch model (DMM). Overall, these thermal characteristics provide valuable insights for designing heterostructures with optimized interfaces and composition.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Polar vibrational excitations and glass-like response in relaxor PMN
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Kehan Cai, Pinchen Xie, Yifan Li, Roberto Car
Relaxor ferroelectrics retain crystalline order while exhibiting glass-like dielectric and thermal responses. Using atomistic models trained on first-principles data, we investigate these responses in the prototypical relaxor Pb(Mg_{1/3}Nb_{2/3})O_3 (PMN). Compositional disorder couples elastic motion to electric polarization, producing a continuum of polar vibrational excitations, unlike the discrete polar optical modes of conventional ferroelectric PbTiO_3. The simulations qualitatively reproduce the temperature dependence of the low-frequency susceptibility, while the calculated far-infrared spectra agree closely with experiments. At low frequencies, disorder in PMN generates a boson peak comprising excess phonon-like modes and quasi-localized excitations. The latter exhibit a quartic frequency dependence of their density of states and pronounced anharmonicity, as in structural glasses. These excess modes account for PMN’s anomalous behavior in the specific heat for temperature higher than 5 K. These results connect the dielectric, optical, and thermal anomalies of a crystalline relaxor through its disorder-induced polar excitation spectrum.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
20 pages, 15 figures
Derivation of the Thiele equation for magnetic skyrmions using the Mori-Zwanzig formalism
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Michael te Vrugt, Mathias Kläui
We use the Mori-Zwanzig formalism to derive an exact generalized Langevin equation governing the dynamics of magnetic skyrmions. Using standard approximations, this generalized Langevin equation is found to reduce to the usual Thiele equation. Our approach provides a general route for obtaining extensions of the Thiele equation applicable to magnetic textures and degrees of freedom not covered by the standard derivation route. It also provides some insights into the microscopic justification of the standard Thiele equation, specifically concerning contributions of fast modes to the form of the drift and diffusion terms in the Fokker-Planck equation for skyrmions.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Ferroelectric switching of odd-parity magnon spin splitting
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Yuhan Liang, Xingyu Yan, Bowen Hao, Ziye Zhu, Tianle Sui, Daniel Pharis, Xiaoxi Huang, Rakshit Jain, Tong Zhou, Di Yi, Wanjun Jiang, Pu Yu, Igor Žutić, Yuan-Hua Lin, Daniel C. Ralph, Tianxiang Nan
Magnetic symmetry can lift spin degeneracy in momentum space without producing net magnetization, generating spin textures classified by their parity under momentum reversal. Even-parity textures have well established in altermagnets. Odd-parity spin textures have recently emerged in electronic bands of compensated magnets, but their counterpart in collective bosonic excitations remains experimentally unresolved. Magnons provide a natural setting for this extension because they carry spin angular momentum through insulating magnets without accompanying charge flow. Beyond realizing this missing state, a broader challenge is to program spin splitting with voltage at room temperature. Here we report room-temperature transport evidence for ferroelectric switching odd-parity magnon spin splitting in multiferroic BiFeO3. Symmetry analysis and spin-wave calculations reveal that the cycloidal chirality splits opposite-spin magnon branches with an odd-in-momentum dependence and sets the sign. Experimentally, an injected in-plane-polarized spin current generates an out-of-plane magnon spin component during propagation. This component exhibits the crystalline angular dependence predicted by theory and reverses upon ferroelectric switching, providing a transport fingerprint of the spin-split magnon state. We use the programmed magnon spin to drive deterministic field-free switching of a perpendicular ferromagnet and demonstrate XNOR logic-in-memory. Our results extend odd-parity spin splitting from fermionic electronic states to bosonic collective modes and establish nonvolatile electrical control at room temperature.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Ultrahigh Thermal Conductivity in Isotopically Ultrapure Single-Crystal Diamond
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Jinwen Liu, Junliang Fan, Zifeng Huang, Zhe Cheng
Diamond has the highest thermal conductivity among natural materials. Reducing isotope scattering can further push the limit of thermal conductivity of diamond. Here, we report the room-temperature thermal conductivity of a diamond single crystal with an exceptionally low ppm-level 13C content. Secondary ion mass spectrometry (SIMS) reveals a 13C concentration of only ~0.00024% and negligible other impurities, placing this sample as the most isotopically purified diamond samples reported to date. Time-domain thermoreflectance measurements show a room-temperature thermal conductivity of ~3100 W m-1 K-1. Although this value is markedly higher than that of natural diamond, it remains comparable to the best reported values for less isotopically 12C pure diamond. This result suggests that additional phonon-scattering mechanisms beyond isotope scattering may exist at this extreme isotopic purification level. Vacancy defects may contribute to the remaining suppression of thermal conductivity.
Materials Science (cond-mat.mtrl-sci)
Universal Dynamics of a Spin-$3/2$ Fermi Gas in Traps with Distinct Spectra
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-22 20:00 EDT
Universal power-law decay of spin-mixing oscillations has been observed in a harmonically trapped spin-$ 3/2$ Fermi gas, whose exactly equally spaced spectrum represents a highly special case. To gain insight into the origin of this behavior, we investigate the dynamics in traps with increasing and decreasing level spacings, represented by the infinite square well and the Pöschl–Teller potential, respectively. Despite pronounced differences in their single-particle spectra, all systems exhibit power-law decay of coherent oscillations, described by $ A(t) = A_{0} - \gamma t^{\alpha}$ . The exponent $ \alpha$ remains insensitive to particle number, interaction strength, and the overall energy scale, but exhibits systematic differences among traps with distinct spectral structures. In contrast, the decay parameter $ \gamma$ is strongly influenced by both the spectral structure and the overall energy scale. These findings demonstrate that power-law decay is not restricted to the harmonic trap but persists across qualitatively distinct spectral structures. The observed variation of $ \alpha$ among different traps further suggests that the underlying single-particle spectrum plays an important role in shaping the decay dynamics.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
13 pages, 7 figures
Thermal Evolution and Disorder Dependence of the Bose-glass: Spatial, Spectral, and Localization Signatures
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-22 20:00 EDT
Madhumita Kabiraj, Raka Dasgupta
In this work, we characterize the glassy character of the Bose-glass phase in a disordered Bose-Hubbard model using three complementary diagnostics: the finite-temperature spectral function, spatial inhomogeneity, and the inverse participation ratio. Spectral analysis, obtained from finite-temperature Green’s function and random phase approximation, shows that disorder introduces localized low-energy states within the Mott gap, eventually closing the gap at sufficiently strong disorder. Spatial inhomogeneity, calculated using the Gutzwiller ansatz, increases sharply with disorder and then saturates at moderate disorder strengths. The inverse participation ratio has been calculated from the exact diagonalization of a small system, and it reveals enhanced localization with stronger disorder. Increasing temperature suppresses these disorder-induced features: the low-energy spectral weight diminishes, the spatial inhomogeneity varies more smoothly, and the IPR decreases. Taken together, these diagnostics show that disorder drives the development of glassy character, while thermal fluctuations gradually wash out its signatures. The early saturation of spatial inhomogeneity compared with the continued evolution of low-energy excitations and the inverse participation ratio demonstrates that no single diagnostic fully captures the evolution of the Bose-glass state, highlighting the need for a combined characterization.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Electronic-Entropy-Driven Phase Transitions in Compressed Iron Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
S. Azadi, S.M. Vinko, C. Crepisson, A. Principi, T.D. Kuehne, M.S. Bahramy
Electronic entropy is usually treated as a secondary correction to structural stability, but under strong electronic excitation it can become a primary thermodynamic driving force. Here we show that electronic entropy can drive both polymorphic and stoichiometric phase transformations in compressed iron oxides. Using finite-temperature density functional theory, we calculate the electronic-temperature-dependent Gibbs free energies of Fe$ _2$ O, FeO, Fe$ _4$ O$ _5$ , Fe$ _3$ O$ _4$ , and multiple Fe$ _2$ O$ _3$ polymorphs, including $ \alpha$ -, $ \iota$ -, $ \zeta$ -, $ \eta$ -, and $ \theta$ -Fe$ _2$ O$ _3$ , over the pressure range 60–260 GPa. At 60-140 GPa, electronic excitation mainly reorganizes the relative stability of Fe$ _2$ O$ _3$ polymorphs, driving transitions from $ \iota$ -Fe$ _2$ O$ _3$ to $ \eta$ -Fe$ _2$ O$ _3$ . At 180 GPa, the free-energy landscape becomes strongly competitive as FeO is stabilized over an intermediate range of electronic temperature, while $ \eta$ -Fe$ _2$ O$ _3$ becomes favourable at higher T. At 220-260 GPa, the lowest-free-energy phase at low T is the Fe-rich compound Fe$ _2$ O, but increasing electronic temperature stabilizes FeO. These results demonstrate that electronic entropy can control not only the relative stability of crystal structures at fixed composition, but also the competition between different iron-oxide stoichiometries. The predicted electronic-entropy-driven phase boundaries provide a route to nonthermal structural transformations in ultrafast and high-energy-density experiments.
Materials Science (cond-mat.mtrl-sci), Plasma Physics (physics.plasm-ph), Quantum Physics (quant-ph)
Matter. Radiat. Extremes 11, 065801 (2026)
Small-supercell and Small-dataset Training Strategy of Machine Learning Interatomic Potentials for Point Defects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Zhenxing Dai, Mingjue Ni, Xinpeng Li, Menglin Huang, Anderson Janotti, Shiyou Chen
Machine learning interatomic potentials (MLIPs) can treat large-scale material systems with near first-principles accuracy and have been widely used to accelerate point-defect simulations. However, the training of MLIPs usually relies on large amounts of DFT data. This issue is particularly pronounced for charged defects, for which DFT calculations of large supercells are required to avoid long-range Coulomb interactions and finite-size effects, making the construction of datasets computationally expensive. In this work, we propose an efficient MLIP training scheme for neutral and lowly charged point defects based on small supercells (less than 100 atoms) and limited number of DFT calculations. The scheme requires only four DFT structural relaxations to construct the training dataset and the trained MLIPs dedicated for the defect can predict the defect formation energies in larger supercells (over 200 atoms) with small errors (mostly smaller than 0.3 eV). Using defects in GaN, SiO$ _2$ , and $ \mathrm{Cu}_2\mathrm{ZnSnS}_4$ as representative examples, we evaluate the extrapolation capability of this scheme for predicting defect total energies and structural relaxations across different supercell sizes. The results show that an MLIP trained only on single small defect supercell produces severe errors when treating large supercells. Incorporating defect data from multiple supercell sizes improves the predictive performance of the MLIP, while adding pristine defect-free bulk supercells further enhances the accuracy. These results provide practical guidance for training MLIP models of defect systems with low computational costs.
Materials Science (cond-mat.mtrl-sci)
Vacancy aggregation enhances NV- spin coherence in diamond: a cluster-correlation-expansion study of multi-vacancy spin baths in semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Annealing a semiconductor makes its vacancies mobile; they aggregate into multi-vacancy complexes that often carry spin. Such centres are a magnetic-noise source for any spin qubit among them, in silicon and silicon carbide as well as in diamond, and they are accordingly blamed for NV- decoherence in irradiated and implanted diamond, with two coherence records credited to removing them. Cluster-correlation-expansion simulations driven by published electron-paramagnetic-resonance parameters invert that attribution. At a fixed paramagnetic spin density a multi-vacancy bath gives a Hahn-echo coherence time 2.7-4.4 times longer than a bath of isolated negative vacancies, constant over three decades of concentration. A bath dephases the qubit because its spins exchange spin projections with one another, and two can exchange only if their transition frequencies match. A fine-structure splitting shifts those frequencies. Were every defect on the same crystallographic site, all would shift alike and still match: worth only a factor 1.3. Real defects occupy symmetry-equivalent sites pointing in different directions, so neighbours land at different frequencies and stop exchanging: a further 1.9. What governs the coherence time is therefore the fraction of bath pairs sharing a transition frequency, not the zero-field splitting. Vacancy aggregation extends NV- spin coherence rather than shortening it.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Coexistence and Interconversion of Multiple-Order Majorana Modes in Topological Superconductor Films with Varying Thickness
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Zhizhong Ding, Chuanbao Zhang, Shunhong Zhang, Xiaoyu Zhu, Wei Qin, Ping Cui, Zhenyu Zhang
We theoretically investigate the thickness-dependent evolution of Majorana modes in $ C_{2h}$ -symmetric topological superconductor films (such as the recently discovered 2M-WS$ 2$ ) proximity coupled with magnetic insulators. For sufficiently thick films, two Majorana bound states coexist as end modes at the surface and interface along a vortex line, with the interfacial mode evolving into a chiral Majorana edge mode upon increasing the proximity-induced exchange field. The intrinsic $ C{2h}$ crystalline symmetry selects two chiral Majorana modes circulating along the hinges on two of the four side surfaces of the film. When the penetration depth of the exchange field is sufficiently shallow, the two circulating modes are localized near the interface, but with qualitatively different subsequent evolutions. One of them further collapses to form two Majorana corner modes, while the other merges with the chiral Majorana mode circulating around the interface. Importantly, the corner modes are well decoupled from the interfacial chiral mode, thereby enabling an unprecedented coexistence of first-, second-, and third-order Majorana modes within a single material platform. We further show that such coexistence persists even in the ultrathin-film limit, where the electric-field-controlled two-dimensional $ Z_2$ topology offers an extra advantage to readily interconvert the multiple-order Majorana modes. These findings highlight the pivotal role of the proper crystalline symmetry in enabling emergence, manipulation, and potential braiding of Majorana modes for demonstrating non-Abelian statistics and fault-tolerant quantum computation.
Superconductivity (cond-mat.supr-con)
18 pages, 10 figures
Slave-Rotor and Auxiliary Chain Analysis of the Mott Transition in a Modified Periodic Anderson Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
The Mott-Hubbard transition is a paradigmatic phenomenon driven by strong electronic correlations. We investigate this transition in a three-orbital modified periodic Anderson model using slave-rotor mean-field theory. A minimal two-site cluster extension is introduced to understand the minimal effects of short-range spatial correlations. In comparison to the single-site solution, short-range spatial correlations reveal a shift of the transition point. Going beyond the slave-rotor analysis, we also evaluate the dynamical self-energy and map it onto the boundary Green’s function of a non-interacting semi-infinite auxiliary chain. For the metallic phase, the resulting hopping pattern corresponds to a topologically trivial generalized Su–Schrieffer–Heeger chain. This construction provides a framework for exploring the possible topological character of the Mott transition in this model.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
Amorphous insulating MoS$_x$ films deposited by magnetron sputtering as a low-index optical coating
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
S.G. Martanov, E.V. Tarkaeva, A.V. Muratov, A.V. Lubenchenko, O.N. Pavlov, A.G. Vitukhnovsky, A.Yu. Kuntsevich
While much effort are now concentrated on exploration of crystalline form of MoS$ _2$ as a two-dimensional material, we show that room-temperature DC magnetron sputtering from pressurized MoS$ _2$ powder target produces amorphous MoS$ _x$ films with optical properties fundamentally different from those of crystalline MoS$ _2$ . The films were found to have a sulfur content of approximately $ x=1.8$ , indicating sulfur deficiency. They are optically isotropic and exhibit rather low optical losses, with a refractive index of about 2 over the visible and near-infrared spectral range. Their compatibility with lift-off lithography and dry etching makes amorphous MoS$ _x$ a promising material for integrated photonic applications.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Optics (physics.optics)
6 pages, 5 figures
Axial thermal expansion from free-energy minimization with temperature-dependent force constants in phonopy: a technical report, with $α$- and $ω$-Ti as the worked example
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
In a hexagonal crystal the $ a$ and $ c$ axes change their lengths at different rates with increasing temperature, and the thermal expansion is described by two coefficients, one for each axis. The equilibrium lattice parameters at each temperature are found by minimizing the Helmholtz free energy over the lattice parameters, and the coefficients are their logarithmic derivatives with respect to temperature. This report describes a procedure for this minimization as implemented in phonopy. The free energy is computed with harmonic force constants at a finite set of values of $ a$ and $ c$ , and a free-energy surface over $ a$ and $ c$ is fitted to these values. In a variant, the harmonic force constants are replaced by temperature-dependent force constants from a self-consistent harmonic approximation, with the forces computed by a machine-learning potential fitted at each of these values. The $ \alpha$ and $ \omega$ phases of titanium are the worked example. Both calculations give negative thermal expansion of the $ c$ axis of $ \alpha$ -Ti at low temperature and none in $ \omega$ -Ti, and they differ most for the $ c$ axis of $ \alpha$ -Ti. The axial coefficients are harder to compute than the volumetric one, because the two axes are coupled in the free energy. In both phases of titanium the thermal effect that lengthens $ a$ also shortens $ c$ . The coefficient of the $ c$ axis is then the sum of two terms of opposite sign that partly cancel, and a small error in either term gives a large relative error in the coefficient. The report measures how much each setting of the procedure changes the thermal expansion coefficients, with the $ c$ axis of $ \alpha$ -Ti as the most sensitive case.
Materials Science (cond-mat.mtrl-sci)
Revealing tilt-driven structural heterogeneity in hybrid improper ferroelectrics by spatially-resolved crystallography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Evie Ladbrook, Jon P. Wright, Mark S. Senn
Domain walls in ferroic oxides can host emergent functionalities that differ fundamentally from those of the surrounding bulk, making their microscopic structure central to understanding and controlling macroscopic behaviour. We use scanning three-dimensional X-ray diffraction to map the spatial evolution of coupled octahedral distortion modes across ferroelastic domain walls in the hybrid improper ferroelectric Ca$ _{2.15}$ Sr$ _{0.85}$ Ti$ _{2}$ O$ _{7}$ . By combining tomographic reconstruction with symmetry-adapted analysis of the octahedral rotation and tilt and associated strain modes, we map their spatial evolution across individual walls in the bulk crystal. We find that the walls are intrinsically extended, with widths far exceeding those expected for conventional Ising-like ferroic interfaces. The wall structure is characterised by a continuous rotation of the tilt order parameter through a tetragonal intermediate. These results provide new microscopic insight into the structural mechanisms governing ferroelastic wall formation, ferroelectric switching, and emergent functionality at domain walls.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 7 figures
The disordered logistic map
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-22 20:00 EDT
The logistic map is a quintessential model in the study of low-dimensional chaos. High-dimensional chaos, on the other hand, presents itself in disordered systems with many interacting and heterogeneously coupled components. Here, we formulate a system of many logistic maps, interacting through disordered couplings. Using a combination of dynamic mean-field theory, random matrix theory and numerical simulations, we show that even the smallest amount of disorder can remove the period-doubling cascade in the conventional logistic map. Instead we find a transition to high-dimensional chaos, marked by an oscillatory instability not previously reported for disordered systems. We also show that with sufficiently strong homogeneous coupling between the maps one recovers elements of the conventional period-doubling cascade. Our findings indicate that well-known phenomena in dynamical systems can be fragile in the face of disorder. At the same time, new phenomena emerge that are neither found in simple low-dimensional dynamics nor in high-dimensional disordered systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
41 pages, 17 figures
Ageing in the exact correlations of the voter model on a fractal
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
The exact behaviour of the enveloppes of the single-time and two-time correlators is found for the voter model on a fractal substrate, with nearest-neighbour interactions. Herein the geometry of the fractal substrate is described by its non-integer geometric fractal dimension $ d_f$ , and its topology and diffusive transport by the distinct spectral dimension $ d_s$ . On the level of the equations of motion of the correlators this can be modelled by considering a space-dependent diffusion constant $ {\cal D}(r)\sim r^{-\theta}$ which implies the spectral index $ \theta$ , itself a function of $ d_f$ and $ d_s$ . With a scaling ansatz, the generic phenomenology of ageing is confirmed and the dynamic exponent $ {z}=2+\theta$ and the autocorrelation exponent $ \lambda=d_f$ are derived. The explicitly found dynamic scaling functions are shown to depend only on the spectral dimension $ d_s$ . The decay of the enveloppe of the density of active interfaces with time is described by the exponent $ \alpha=1-d_s/2$ for $ d_s<2$ , confirming the results of preexisting numerical simulations.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph)
Latex2e, 1+39 pp, 4 figures, 2 tables
Heterogeneous planar diffusion with axisymmetric power-law decaying diffusion coefficient under stochastic resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Trifce Sandev, Sebastien Fumeron, Malte Henkel, Ervin K. Lenzif
We analyse two-dimensional isotropic heterogeneous diffusion with a radially decaying diffusion coefficient $ D(\rho)=D_0/\rho^2$ , subject to Poissonian stochastic resetting to the origin. Since multiplicative noise makes the process interpretation-dependent, we treat the Itô, Stratonovich, and Hänggi–Klimontovich prescriptions within a single approach. For each, we obtain the exact probability density function, the non-equilibrium stationary state induced by resetting, the mean squared displacement, and the first-passage properties. The non-equilibrium stationary state is governed by modified Bessel functions and departs from the Laplace form found for homogeneous diffusion under resetting, while the mean squared displacement saturates at long times as $ \langle\rho^2\rangle\sim\bar{r}^{-1/2}$ , $ \bar{r}$ being the resetting rate. The mean first-passage time to an absorbing boundary exhibits an optimal resetting rate at which it is minimised. In addition, we incorporate memory effects through a subordination (continuous-time random walk) approach with a power-law kernel, deriving the fractional Fokker–Planck equation together with the non-equilibrium stationary state, the mean squared displacement expressed via the three-parameter Mittag-Leffler function, and the first-passage statistics; the optimal resetting rate increases as the memory exponent decreases.
Statistical Mechanics (cond-mat.stat-mech)
Latex 2e, 23 pp, 6 figures
Spin-Orbit Induced Confinement of Correlated Bound States in the Continuum
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Kai Chen, Junyan Guan, Zhongming Gu, Jie Zhu
Repulsively bound doublons are two-particle composites formed by strong interactions and are usually separated from the scattering continuum. Introducing spin-orbit coupling fundamentally alters the underlying band structure, providing a powerful tuning knob to shift these isolated pairs toward this continuum. However, because entering such a regime typically dictates immediate dissociation, whether this coupling can drive these pairs inside while preserving their bound nature constitutes a fundamental unresolved challenge. Here we show that spin-orbit coupling in the one-dimensional Fermi-Hubbard model can drive doublons into the two-particle scattering continuum. Most of these states hybridize with extended channels and decay, whereas a subset remains decoupled and spatially bound, forming many-body bound states in the continuum (BICs). We map the interacting two-particle problem onto a two-dimensional lattice of coupled acoustic cavities, and experimentally observe both the radiating doublon continuum and the confined BIC states. These results demonstrate that spin-orbit coupling can turn selected doublons into interaction-induced BICs, deepening the understanding of continuum physics for interaction-bound pairs.
Strongly Correlated Electrons (cond-mat.str-el)
Non-equilibrium dynamics of drift-diffusion process under threshold resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Rahul Das, Satya N Majumdar, Arnab Pal
We study the emergence of non-equilibrium steady states (NESS) in stochastic processes under threshold resetting, an event-driven protocol in which the system resets to its initial configuration upon crossing a prescribed spatial boundary (threshold). In contrast to externally driven resetting, whose steady-state properties are well understood, the behavior under threshold resetting remains largely unexplored. We derive general conditions for the existence of a NESS and show that, whenever it exists, the steady state at a given position $ x$ can be expressed as the ratio of two fundamental quantities: the mean local time (MLT) at $ x$ and the mean first-passage time (MFPT) to hit the threshold. In particular, for noisy systems, a finite MFPT guarantees the existence of a NESS. As an illustrative example, we analyze a drift-diffusion process in one dimension and uncover rich intermediate-time dynamics, including anomalous relaxation in the spatial distribution, damped oscillations in the moments and in the mean-squared displacement (MSD), governed by system parameters. Our findings provide a general understanding of the emergence of non-equilibrium steady states and relaxation dynamics under threshold resetting, revealing how induced events shape the spatial and temporal properties of a broad class of stochastic processes.
Statistical Mechanics (cond-mat.stat-mech)
16 pages, 8 figures
Charge-4e Superconducting Ground State without Pair Condensation: Exact Quartet Dynamics, Rigorous Order, and a Microscopic Route
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Jin-Tao Jin, Pengfei Li, Yi Zhou
A direct charge-(4e) superconductor exhibits coherent four-electron order while every charge-(2e) pairing channel remains uncondensed. We establish three complementary results. First, building on the (\eta)-clustering states and bipartite parent of Yoshida and Katsura, we formulate and exactly solve a minimal two-term parent on any connected graph. Its fixed-number ground states have quartet off-diagonal long-range order (ODLRO) without charge-(2e) ODLRO, while an exact mapping to classical hard-core exclusion dynamics yields the full fixed-sector gap and a branch of quartet-density modes. Nonzero quartet stiffness and vanishing inverse quartet compressibility identify this (z=2) parent as a phase-separation boundary. Second, for a finite-range fermionic family with explicit quartet transfer and sufficiently large onsite penalty, we rigorously prove quartet ODLRO without charge-(2e) ODLRO at half quartet filling, both at the hypercubic XY point for (d\geq2) and throughout a finite XXZ interval on the square lattice. Third, we derive a strong-coupling realization using only electron hopping and two-body interactions. With local gap (U_0), pair hopping (K) generates quartet motion at order (K^2/U_0), whereas electron hopping (t) first contributes at order (t^4/U_0^3); charge-(2e) excitations remain gapped at (O(U_0)). On bipartite lattices, positive inverse quartet compressibility opens an asymptotically controlled homogeneous (z=1) regime with short-ranged pair correlations, while negative curvature drives phase separation.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
19 pages, 2 figures
Effective Mass Approach to Dynamics of Non-Markovian Systems with Short Memory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Memory is an inherent feature of the dynamics of physical systems. It typically emerges when the complex structure of the system is simplified during the modeling process, obscuring a part of its underlying behavior. Consequently, the correct description of such a physical model requires knowledge of not only its present, but also its past states, leading to non-Markovian dynamics. The resulting interactions depending on the system history, however, introduce a significant layer of mathematical complexity. For this reason, when the memory time is significantly shorter than the time scales characterizing the dynamics, it is typically neglected at the cost of losing information regarding its role in the system behavior. In this dissertation, I introduce a novel methodology, namely the effective mass approach, which bridges the Markovian and non-Markovian regimes and provides an accessible framework for analyzing systems with short memory. In this method, the non-Markovian system is approximated with its Markovian counterpart, in which the short-memory effects are encapsulated within an effective mass. I then utilize this approach to demonstrate that the impact of short memory on physical dynamics can be remarkably pronounced. In particular, I show that the directed transport of a Brownian particle in an environment exhibiting temporal correlations can be reversed relative to its behavior in a memoryless medium. Moreover, I propose a setup wherein memory serves as a~control parameter for the generation of random information bits. Collectively, the results of this dissertation underscore the critical importance of short-time correlations in microscopic systems.
Statistical Mechanics (cond-mat.stat-mech)
Doctoral dissertation in a form of a guide through a collection of scientific articles (with minor corrections after the review). Written under the supervision of Jakub Spiechowicz. 53 pages, 12 figures + 1 logo
On the dual character of Zn impurity in SnTe: Tuning thermoelectric and topological properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Kacper Pryga, Bartlomiej Wiendlocha
We present a first-principles study of the electronic structure and thermoelectric properties of Zn-doped SnTe using the Korringa-Kohn-Rostoker method within the coherent potential approximation, complemented by pseudopotential calculations. SnTe is a lead-free analogue of PbTe and a candidate thermoelectric material in which Zn doping has been experimentally reported to enhance the performance of $ p$ -type samples. We show that Zn introduces a resonant-like impurity state, located within the conduction band, which evolves strongly depending on the Zn concentration. This feature leads to a significant enhancement of the thermopower in $ n$ -type SnTe. In the valence band, Zn doping induces L-$ \Sigma$ band convergence, also resulting in an increased $ p$ -type Seebeck coefficient over a broad concentration range and delaying the onset of the bipolar effect. We further demonstrate that the Zn-induced band-structure modifications drive a transition from an inverted to a trivial band ordering, indicating a controllable topological phase transition. Our results clarify the microscopic role of Zn in SnTe and identify doping as a mechanism for simultaneously tuning thermoelectric and topological properties.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
21 pages + Supplemental Material. Accepted for publication in Physical Review B
Parallel Simulation of Josephson Junctions With Multiplicative Noise
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Vincenzo Pierro, Luigi Troiano, Elena Mejuto Villa, Sergio Pagano, Giovanni Filatrella
Parallel graphic processing units have been employed for fast simulations of the switching dynam- ics of Josephson junctions subject to critical current fluctuations. Such a system is modeled by a nonequilibrium washboard model with multiplicative noise, for which analytical results are lacking. The proposed approach allows us to execute extensive numerical simulation in short time and with relatively inexpensive resources. This allows us to fully characterize the effect of the noise on the junction switching current distributions at realistic bias current sweeprates.
Superconductivity (cond-mat.supr-con)
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 28, NO. 7, OCTOBER 2018 p 1700404
Avalanche Size and Interevent Time Statistics in Amorphous System
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Thomas Muhren, Roberto Benzi, Mauro Sbragaglia, Jeannot Trampert, Federico Toschi
The intermittent, stick-slip flow of amorphous systems is characterized by avalanches whose statistical properties display robust power-laws. In this paper, we study avalanche statistics in a field theoretical model of a soft-glassy system under shear. The order parameter in our model is the fluidity, which is related to the local rate of plastic events in a soft-glass. While avalanche sizes $ S$ have been extensively characterized, the statistics of interevent times $ t_i$ have remained largely unexplored. Here, we find that both $ S$ and $ t_i$ are power-law distributed and that their scaling exponents satisfy a precise relation. The model enables the analytical derivation of the scaling exponents and the reproduction of the behavior observed across a wide class of amorphous systems.
Statistical Mechanics (cond-mat.stat-mech)
Stochastic optimisation method for estimating large deviations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Daniël W. H. Cloete, Hugo Touchette
A stochastic optimisation method was recently proposed to efficiently compute large deviation functions, used in statistical physics to characterise the fluctuations of nonequilibrium systems, modelled as Markov processes. The method, called LDSTOP, combines numerical techniques from control theory and machine learning to iteratively construct the “driven process”, a controlled version of the Markov process used as a model of nonequilibrium system that realises a given fluctuation or large deviation of that system in an optimal way. Compared to other methods based on spectral approximations, importance sampling, cloning or splitting, LDSTOP is simple, flexible, and scalable, as it works by simulating single trajectories that are gradually guided towards the driven process. Here, we illustrate these advantages by applying the method on the full range of Markov processes considered in applications, namely, discrete-time Markov chains, continuous-time jump processes, and diffusion processes. For each type, we define the objective function to be optimised, explain different options available for representing the driven process (using, e.g., neural networks), and provide implementation details through simple applications. With these contributions, we aim to showcase the method’s efficiency, as well as its ease of use when combined with available machine learning packages, such as PyTorch, TensorFlow and JAX, for simulating stochastic processes and solving high-dimensional optimisation problems.
Statistical Mechanics (cond-mat.stat-mech)
30 pages, 9 figures
Onset of a Fold Cascade in a Hopf Texture Driven by a Navier–Stokes Blow-Up Analog
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-22 20:00 EDT
A two-component Bose–Einstein condensate can host a pseudospin Hopf texture while its thermal cloud obeys viscous Navier–Stokes dynamics. Motivated by OpenAI’s reported finite-time singular solution, we drive such a texture with a surrogate of the collapsing core, using an effective Madelung–Schrödinger theory with a Faxén-like advective correction. The texture undergoes fold-mediated creation and annihilation of preimage pairs at conserved Hopf charge with the first one-to-three transition confirmed to obey the square-root opening of a Thom $ A_2$
Quantum Gases (cond-mat.quant-gas), Mathematical Physics (math-ph), Pattern Formation and Solitons (nlin.PS)
2 figures
Carrier-mediated spin helices in low-dimensional systems: Josephson-interference features and correlation renormalization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Yung-Yeh Chang, Chen-Hsuan Hsu
Carrier-induced helical magnetism can arise in interacting one-dimensional systems coupled to localized moments. Here, we investigate the coupled-wire sliding-Luttinger-liquid counterparts with and without valley degrees of freedom, using isolated Tomonaga-Luttinger liquids as reference limits. The carrier spin susceptibility mediates a Ruderman-Kittel-Kasuya-Yosida interaction that selects the helical ordering wave vector, while interchannel correlations lock the relative helix phases and stabilize a collective quasi-two-dimensional texture. Using a variational treatment, we estimate the helix-induced partial gap and analyze the reconstruction of the remaining gapless carrier modes. To probe the spatial texture through transport, we incorporate the helix into an anisotropic superconductor-normal-metal-superconductor Josephson junction motivated by the coupled-channel structure of twisted bilayer WTe$ _2$ . We exploit flux focusing near the junction interfaces to make an applied in-plane field a controlled probe of the spin helix. Relative to junctions without the helix, the helical exchange field modifies the central-lobe width and relative lobe weights. In the transverse-channel geometry, it also produces field-dependent side-lobe asymmetry and central-peak displacement, which remain negligible in the matched references for the parameters considered. The reconstructed carrier sector also exhibits modified local-density-of-states exponents, spin-relaxation behavior, and competing correlations, with distinct signatures in isolated and coupled-wire systems. Our results connect collective helical order in coupled-wire systems to carrier-sector reconstruction and identify field-tunable Josephson interferometry as a complementary transport probe of the spatial spin texture.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
25 pages, 3 figures, 5 tables
Phase diagram morphology shapes droplet propulsion in chemical gradients
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Stefan Köstler, Malcolm Steen, David Zwicker
Droplets in complex environments often encounter compositional gradients that drive their propulsion. For example, surfactant gradients induce surface-tension-driven propulsion via the Marangoni effect. Here, we show that such propulsion emerges generically, even in the absence of surfactants. Employing a thin-interface approximation, we derive a compact expression for the droplet velocity in terms of droplet size, viscosity, the sensitivity of surface tension to a regulating component, and the chemical potential gradient of that component. Our theory reveals that droplets move toward regions of lower stability, as encoded in the morphology of the phase diagram, particularly near critical points. Numerical simulations confirm these results, which establish a general route to predicting and designing droplet motility from the phase behavior of complex fluids.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Fluid Dynamics (physics.flu-dyn)
7 pages, 5 figures, and Appendix
Detection of signals in presence of noise through Josephson junction switching currents
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
O. V. Pountougnigni, R. Yamapi, C. Tchawoua, V. Pierro, G. Filatrella
Josephson junctions can be employed to reveal a sinusoidal signal in presence of Gaussian noise. To mimic realistic setups, the detection is performed linearly ramping the bias current until a switch to the finite voltage occurs; the analysis of the resulting switching currents can be exploited to decide about the presence of the harmonic drive. The signal is applied in two conditions: with an unknown initial phase (incoherent strategy) and with a known initial phase (coherent strategy). In both conditions, the analysis of the efficiency of the detection, performed through the signal-to-noise ratio, as estimated by the Kumar-Carrol index, shows that the dependence upon the Josephson junction ramp rate is beneficial, especially for relatively fast speed. One can conclude that the collection of the switching currents is a robust technique, and thus it is possible to exploit the advantages of a predetermined finite time to collect the data.
Superconductivity (cond-mat.supr-con)
Physical Review E 101, 052205 (2020)
The Superconducting Talbot Effect in Phased-Array Josephson Junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
We introduce the superconducting Talbot effect—a macroscopic quantum self-imaging phenomenon occurring when proximitized Cooper pairs propagate through a ballistic two-dimensional electron gas. By configuring periodic superconducting leads into a phased-array Josephson junction with programmable phase differences, we demonstrate active steering of the resulting superconducting Talbot carpet. To overcome transport resolution limits, we design a Vernier-scale collector array that performs sub-wavelength sampling of the fractional Talbot pattern. This approach maps real-space quantum interference with high robustness to disorder, enabling direct extraction of Fermi wavelengths across helical, spin-degenerate, and spin-orbit-split Fermi surfaces. Tight-binding numerical calculations on a square lattice validate the real-space interference patterns. Our results establish a versatile framework for coherent wavefront engineering and quantum materials diagnostics in superconducting optics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
14 pages, 5 figures
Corbino-Enhanced Supersonic Acoustic-Emission Threshold in a GaAs Two-Dimensional Electron System
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
A. D. Levin, A. S. Jaroshevich, Z. D. Kvon, V. A. Chitta, M. S. Aksenov, D. V. Dmitriev, A. K. Bakarov, G. M. Gusev
We report nonlinear differential-resistance measurements in a high-mobility GaAs/AlGaAs two-dimensional electron system patterned in a Corbino geometry. At zero magnetic field, $ R_{\mathrm{diff}}(I_{dc})$ exhibits a pronounced polarity-selective threshold peak on the negative-current branch, gradually suppressed by a perpendicular magnetic field. We interpret the Corbino anomaly as a local Cherenkov-like threshold for acoustic phonon emission, enabled by the radial current concentration $ j_r(r)=I/(2\pi r)$ , which drives the local electron velocity above the sound velocity in a region adjacent to the inner contact. The polarity selectivity is attributed to Peltier heating and cooling, which modify the local thermal and boundary conditions near the contact, rather than to the kinematic threshold itself. Our results identify the Corbino geometry as a sensitive platform for probing local nonequilibrium electron–phonon processes in a high-mobility electron system within an independently established hydrodynamic-crossover regime and suggest that the inner Corbino contact can act as a geometry-defined source for supersonic acoustic emission.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 5 figures
Phys.Rev. B 114, 165303 (2026)
Random-matrix and transport frequencies in eigenstate spectral functions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Kadir Çeven, Rohit Patil, Marcos Rigol, Fabian Heidrich-Meisner
The fact that generic isolated many-body quantum systems thermalize is understood using the eigenstate thermalization hypothesis (ETH). In recent years, there has been much interest in the behavior of the ETH spectral functions, which characterize the smooth dependence of the variance of the off-diagonal matrix elements of observables on the associated energy and frequency, and whose low-frequency part contains information about the long-time dynamics. In finite systems described by the ETH, the spectral functions are expected to exhibit plateaus below a characteristic frequency $ \omega^{}{\mathrm{ETH}}$ . In this regime, the statistics of the matrix elements of observables are expected to be described by random matrix theory. Related frequencies that have been studied in the literature are $ \omega^{}{\mathrm{SFF}}$ , which controls the onset of random-matrix behavior in the spectral form factor, and the transport frequencies $ \omega^{}{\mathrm{tr}}$ , which are derived from transport coefficients. However, a direct quantitative comparison of these frequencies is lacking. Using exact diagonalization, we conduct such a comparison for the spectral functions of current operators in clean and disordered quantum spin ladders with diffusive energy and spin transport. We find clear evidence for the expected low-frequency plateaus in the ETH spectral functions. For the accessible system sizes, $ \omega^{}{\mathrm{SFF}}$ is consistent with the extent of the plateaus, while the transport frequencies are systematically larger and lie in the nonuniversal regime of the spectral functions. Our findings highlight the need to better understand the origin of these quantitative differences.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
13 pages, 9 figures
New theoretical model of the dynamic anomalies in HTc superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
New theoretical model of the dynamic current-voltage characteristics anomalies in HTc superconductors in slowly varying magnetic field has been proposed. The model is based on an analysis in details of the magnetic flux penetration into HTc superconducting slab in such case. The comparison of model with previous experimental data has been presented. Theoretical analysis resulting from a new solution of diffusion equation is given as well as other one based on phenomenological critical state model.
Superconductivity (cond-mat.supr-con)
Raman Scattering Evidence for Fluctuating Kagome-Plane Moments in $\mathrm{B} \parallel [111]$ in Pr$_2$Zr$_2$O$_7$ pyrochlore
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Yuanyuan Xu, Huiyuan Man, Nan Tang, Li Xiang, Sami Muhammad, Komalavalli Thirunavukkuarasu, Dmitry Smirnov, Satoru Nakatsuji, Natalia Drichko
The exotic magnetic properties of the pyrochlore Pr$ _2$ Zr$ _2$ O$ _7$ are determined by the coupling of spin, orbital, and lattice degrees of freedom. Magnetism in this material originates from the non-Kramers Pr$ ^{3+}$ ion, and the exotic behavior has been discussed both in the framework of dipole-quadrupole properties of magnetic moments and disorder splitting the non-Kramers doublet. We use magneto-Raman spectroscopy to probe the crystal electric field (CEF) excitations of Pr$ ^{3+}$ in magnetic fields up to 14 T applied along the [100] and [111] crystallographic directions at 2 K. For $ \mathrm{B}\parallel[100]$ , the field evolution of the Raman active crystal field modes is quantitatively described by conventional Zeeman splitting of the Pr$ ^{3+}$ ground state doublet, including the thermally populated upper Zeeman branch at elevated temperature. For $ \mathrm{}{B}\parallel[111]$ , the spectra separate into responses from the triangular and kagome sublattices, and the CEF excitations of Pr$ ^{3+}$ on the triangular lattice exhibit the expected Zeeman shift consistent with full moments polarization. In contrast, the CEF excitations of Pr$ ^{3+}$ on the kagome lattice do not split as expected and instead broaden strongly with increasing field. This behavior is inconsistent with a static polarized configuration and is captured phenomenologically by a motional-narrowing description in which the kagome plane moments fluctuate between Zeeman-split levels on a meV timescale. This result offers a natural explanation for the reduced magnetization observed in $ \mathrm{}{B}\parallel[111]$ and provides further evidence of the dipole-quadrupole properties of magnetic moments. It highlights Raman scattering as a sensitive probe of exotic spin-orbital dynamics in frustrated magnets.
Strongly Correlated Electrons (cond-mat.str-el)
Infrared evidence for strong $C_{3}$ symmetry breaking in 1$T$-TiSe$_{2}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Esther van Grondelle, Kai Rossnagel, Jasper van Wezel, Erik van Heumen
The interplay between lattice and electron degrees of freedom gives rise to competing ordered states in quantum materials, which can lead to a series of subsequent symmetry breaking transitions. While the differences are often subtle, these phases can be distinguished by their remaining point group symmetries. Here, we use infrared optical spectroscopy to probe symmetry breaking at the charge density wave transition of 1$ T$ -TiSe$ {2}$ . We uncover a previously unobserved splitting of a doubly degenerate $ E_u$ optical phonon at $ T{\mathrm{CDW}}\approx$ 190 K that constitutes direct evidence for the breaking of three-fold rotational symmetry. Our finding rules out proposals where the CDW transition to a low temperature chiral or nematic phase takes place through an intermediary state that preserves three-fold symmetry. The energy difference between the two former $ E_{u}$ partners can only be explained by large $ C_{3}$ breaking distortions of the same order of magnitude as previously observed changes in bond lengths, suggesting that $ C_{3}$ symmetry breaking plays a dominant role in the CDW transition. The linewidth of the single phonon mode above $ T_{\mathrm{CDW}}$ could be consistent with a fluctuating state where three-fold symmetry is also broken.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 3 figures, 2 appendices with 2 figures
Rapidly prototyping kagome flat band physics with acoustic metamaterials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Jiatong Yang, Benjamin H. November, Yiting Huang, S. Minhal Gardezi, Harris Pirie, Jennifer E. Hoffman
Flat bands with vanishing group velocity and quenched kinetic energy provide fertile ground for correlated states and exotic phenomena such as unconventional superconductivity. Yet, engineering and characterizing flat bands in quantum materials is time-consuming and costly, limiting the exploration of the vast design space of possible flat band systems. Acoustic metamaterials offer an accessible alternative: they can be easily simulated, cheaply fabricated, and quickly measured. Here we present a complete workflow to rapidly prototype flat band systems using acoustic metamaterials. Our design directly implements a tight-binding model using air cavities as lattice sites connected by channels that control hopping, allowing it to generalize to diverse lattice geometries. Using the kagome lattice as a proof-of-concept, we demonstrate excellent agreement between tight-binding theory, finite-element simulations, and experimental measurements. We then design a family of extended kagome lattices whose added sites cancel successively longer-range hopping, flattening the flat band. With fabrication and measurement requiring hours rather than months and a total cost orders of magnitude lower than quantum materials, our approach enables rapid iteration through candidate lattices, facilitating the discovery of new flat band physics in quantum materials.
Strongly Correlated Electrons (cond-mat.str-el)
Lowest-known Energy Configuration of $N=100,000$ Coulomb Charges in a Disk: Breaking the $10^{5}$ Barrier
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Georgiy K. Lavrov, Eduard G. Nikonov
We report the first calculation of the lowest-known energy configuration for $ N=100,000$ classical point charges confined to a disk and interacting via the $ 1/r$ Coulomb potential - a system size never before achieved for the Thomson problem in a disk, more than doubling the previous record of $ N=40,886$ reported by Amore and Zarate. An adaptive defect-targeting subdomain optimization strategy yields an approximately linear growth of the wall-clock time per cycle with $ N$ ; for $ N=100,000$ a single $ 24$ -core CPU workstation without GPU acceleration required $ \approx31$ hours. The energy $ E_{\min}=7.80466624157\times10^{9}$ deviates from the asymptotic expansion fitted to $ 100\le N\le5000$ data by only $ 2.525\times10^{-7}$ , providing a stringent test of its extrapolation to unprecedented scales. Bond-orientational order analysis reveals a polycrystalline bulk threaded by radial grain boundaries, establishing a new benchmark for two-dimensional Coulomb systems.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Optimization and Control (math.OC), Classical Physics (physics.class-ph), Computational Physics (physics.comp-ph)
Article: 12 pages, 1 table; Supplemental Material: 6 pages, 6 figures, 1 table
Observation of Kondo Effect in Rhombohedral Graphene Superlattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Xin Liao, Qing Yin, Huiwen Wang, Jing-Wei Dong, Jun-Xi Chen, Si-Li Wu, Cai-Zhen Li, Guowei Lyu, Kenji Watanabe, Takashi Taniguchi, Wei Jiang, Yu-Gui Yao, Zhi-Min Liao
Kondo effect in strongly correlated systems arises from the antiferromagnetic coupling between itinerant conduction electrons and localized magnetic moments, giving rise to a variety of exotic quantum phenomena. Two-dimensional moiré superlattice systems provide a highly tunable platform featuring topological flat bands, where Wannier orbitals are spatially confined by the periodic moiré potential and serve as localized magnetic moments, enabling the observable Kondo effect. Here we experimentally demonstrate Kondo interactions in hexalayer rhombohedral graphene moiré superlattices through magneto-transport and temperature-dependent measurements. With increasing magnetic field, the magnetoresistance exhibits an increase-decrease transition across a critical field B_c, while the Hall resistance R_xy undergoes a sign reversal near B_c. Moreover, as temperature decreases, the longitudinal resistance R_xx first increases logarithmically and then decreases following a T^2 behavior, indicating a transition to heavy fermion liquid. These behaviors can be consistently explained by the breakdown of Kondo singlets induced by either magnetic field or temperature, which liberates carriers previously bound to localized moments, thereby enhancing conductivity and altering the dominant carrier type. Furthermore, our results demonstrate that the Kondo interaction can be continuously tuned by both carrier density n and displacement electric field D, and suggest the emergence of a Kondo insulating state. Our findings provide deep insight into the Kondo effect in moiré engineered flat-band systems, paving the path for exploring exotic correlated quantum phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 4 figures
From harmonic to sound-like oscillations in a quantum gas confined in a gravity compensated shell trap
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-22 20:00 EDT
Matthieu Cassus (LPL), Rishabh Sharma (LPL), Maxime Pesche (LPL), Laurent Longchambon (LPL), Thomas Badr (LPL), Romain Dubessy (PIIM), Hélène Perrin (LPL)
We study the center of mass oscillations of a quantum gas in a shell shaped trap in the presence of a vertical force opposed to gravity. The measured harmonic frequency at the bottom of the shell is compared with an analytical formula for the trap potential including corrections beyond the rotating wave approximation. When gravity is partially compensated, a quartic correction to the harmonic motion has to be included due to the shell curvature. As gravity is nearly canceled, the quantum gas occupies a large fraction of the lower hemisphere. Driving the center of mass induces internal excitations in the quantum gas, whose time evolution is governed by the presence of sound waves. Relaxation processes induce a strong damping of the center of mass oscillation in this limit.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
11 pages, 9 figures, submitted
Optimal probing scale for current fluctuations in a Brownian gyrator
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
A driven colloidal rotor sustains a circulating current whose fluctuations one would like to bound. Any such bound rests on how strongly the current responds to a perturbation and on how much extra dissipation that perturbation costs, so there is a well-posed question of where to push: the response per unit Onsager-Machlup cost depends on the radius at which the probe acts, and is maximised at a definite one. We answer this for the Brownian gyrator and a quadrupolar shear under a Gaussian envelope, a probe chosen so that linear response is exactly blind to it at every observation window, so that the entire signal is second order. The problem separates: the cost is radial and does not see the circulation, while the response lives in the $ m=3$ angular sector, where the resolvent reduces to Kummer’s equation with $ b=4$ and the susceptibility is a hypergeometric function of the envelope width. Maximising the ratio gives the optimal probing radius in closed form. It is set by whichever of the system’s two clocks is faster: for weak driving $ r^\ast=1.1264\sqrt{D/\gamma}$ , the thermal radius of the trap, and for strong driving $ r^\ast=1.5563\sqrt{D/\Omega}$ , the distance diffused in one radian of rotation, with the trap stiffness dropping out entirely. The crossover is at $ \Omega=\gamma$ . Both limits, and the prefactors, are confirmed against direct simulation.
Statistical Mechanics (cond-mat.stat-mech)
5 pages, 1 figure. Code and data: doi:https://doi.org/10.5281/zenodo.22877097
III-V antiphase boundaries are not generated by Si or Ge substrate step edges
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Charles Cornet, Sreejith Pallikkara Chandrasekharan, Audrey Gilbert, Milan Silvestre, Rozenn Bernard, Pascal Turban, Gilles Patriarche, Eric Tournie, Laurent Pedesseau, Jean-Baptiste Rodriguez
We critically review recent experimental and theoretical advances on the valence- and structure-mismatched heteroepitaxy of III-V semiconductors on group-IV substrates. We examine key aspects including wetting behavior, atomic configurations at the hetero-interface, substrate passivation, and the stability of antiphase boundaries (APBs). By synthesizing these findings with pioneering studies, we propose a refined description of antiphase boundaries formation. Our analysis shows that hetero-interface formation is dictated by substrate terrace reconstruction, demonstrating that APBs are not generated at monoatomic step edges. This generalized III-V/IV growth framework provides new insights for the integration of III-V semiconductors on group-IV platforms and, more broadly, for valence-mismatched heteroepitaxy.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Interface engineering of spin triplet Cooper pairs for spin-valve implementation
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Debashree Nayak, Abhisek Sahoo, Pratap Kumar Sahoo, Kartik Senapati
Spin singlet Cooper pairs can be converted into equal-spin triplet pairs at a superconductor/heavy-metal interface under suitable conditions. Under current carrying conditions, these triplet correlations can give rise to a non equilibrium spin moment in the heavy metal through the predicted supercurrent spin-Hall effect. Here we demonstrate that this current induced triplet spin moment, in conjunction with the magnetic moment of a ferromagnetic layer, can enable a magnetic spin-valve response in Nb/Pt/Ni/Pt/Nb vertical nano-devices. The magnitude of this spin-valve effect depends on the efficiency of singlet-triplet Cooper pair conversion at the Nb/Pt interface. In order to facilitate efficient triplet generation, we deliberately introduced interfacial roughness to introduce finite Rashba spin-orbit coupling at the Nb/Pt interface and an out-of-plane component of magnetic moment at the Ni interface. In contrast, no discernible spin-valve response was observed in devices with smooth interfaces within measurement resolutions. Since the magnetic moment of the Ni layer and the current-induced triplet spin moment in the Pt layer are independently switchable using a magnetic field and bias current, respectively, the spin valve can be controlled via either parameters. These results demonstrates a novel approach to directly utilizing the spin polarized triplet Copper pairs in superconducting spintronic applications.
Superconductivity (cond-mat.supr-con)
Generalized conditions for odd-frequency pairing in superconducting systems
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Florian Kayatz, Annica M. Black-Schaffer, Jorge Cayao
Odd-frequency superconducting pairing has been predicted to arise in many systems and is known to lead to phenomena such as paramagnetic Meissner response and long-range superconducting proximity effect. Here, we provide generalized necessary and sufficient conditions for odd-frequency pairing appearing in any superconducting system, from bulk superconductors to superconducting hybrid structures. This generalizes an earlier first-order expression in multiband bulk superconductors to all superconducting systems and to all orders, in both order parameter and frequency. We then apply the derived conditions to several systems, including superconducting-ferromagnet and superconducting Josephson junctions, as well as a transition metal dichalcogenide monolayer proximitized by a conventional superconductor, where the generalized conditions are used to understand the properties of the superconducting state.
Superconductivity (cond-mat.supr-con)
9 pages, 4 figures. Comments welcome
Electronic Reconstruction Towards Topological Superconductivity in FeTe
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-22 20:00 EDT
Hongtao Rong, Yang Ge, Zi-Jie Yan, Haoran Lin, Bing Xia, Xiaoda Liu, Zihao Wang, Pu Xiao, Lok-Kan Lai, Stephen Paplini, Jiatao Song, Jiangang Yang, Peter J. Hirschfeld, Shuolong Yang, Jiabin Yu, Cui-Zu Chang
The recent discovery of intrinsic superconductivity in stoichiometric FeTe films has renewed interest in the Te-rich end member of the iron chalcogenides for studies of unconventional and topological superconductivity, yet its intrinsic electronic structure remains unresolved. In this work, we combine molecular beam epitaxy, angle-resolved photoemission spectroscopy (ARPES), electrical transport measurements, density functional theory, and embedded dynamical mean-field theory to track the electronic reconstruction of 20-unit-cell FeTe films as Te annealing progressively removes excess interstitial Fe and drives the system from an antiferromagnetic metal to a superconductor. We find that this evolution is accompanied by recovered quasiparticle coherence, reduced electronic correlations, a Lifshitz transition, and a topological phase transition, yielding dxy-dominated hole and electron pockets that favor inter-pocket scattering. In addition, a shallow dxz/dyz-derived hole band located about 2 meV below the Fermi level may provide an incipient-band pairing channel, while scattering between the two electron pockets at M may offer additional pairing channels. High-resolution polarization-dependent laser ARPES measurements further reveal a topological surface state whose circular dichroism is consistent with the expected orbital-angular-momentum texture of stoichiometric FeTe. These results establish the intrinsic low-energy electronic structure of superconducting FeTe and identify the electronic states most relevant to superconductivity. The coexistence of intrinsic superconductivity and a topological surface state establishes stoichiometric FeTe as a promising platform for exploring topological superconductivity and possible Majorana bound states.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
35 pages and 4 figures. Comments are very much welcome
Navier-Stokes hydrodynamics near the critical point with out-of-equilibrium modes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Md Hasanujjaman, Golam Sarwar, Mahfuzur Rahaman, Abhijit Bhattacharyya, Jane Alam
We investigate how slow out-of-equilibrium modes (OEM), introduced to extend the regime of validity of hydrodynamics near the critical point, fundamentally reshape the power spectrum of dynamical density fluctuations. We have used the equation of motion of slow modes for the situation when the extensive nature of thermodynamics is not altered due to the introduction of OEM. We find that the extensivity condition puts an extra constraint on the coupling of OEM with the four divergence of velocity. In the absence of OEM, the dynamic structure factor exhibits three Lorentzian peaks, one at zero frequency ($ \omega$ ), called Rayleigh peak and the other two called Brillouin peaks located symmetrically about $ \omega=0$ . When the system is away from the critical point the inclusion of the OEM preserves the symmetry of the distributions but all the peaks acquire reduced widths and the Brillouin peaks adopt unequal heights. Irrespective of the value of OEM (zero or nonzero) the Brillouin peaks vanish near the critical point. The width of the Rayleigh peak substantially reduced in presence of OEM. Such reductions of the widths in presence of the OEM indicates the reduction in the decay rate of the fluctuation which leads to slowing down of decay of the fluctuations, a distinctive feature of the critical point.
Statistical Mechanics (cond-mat.stat-mech)
23 pages, 13 figures
Anisotropic Surface State Band Splitting and Low Energy Flat Bands in 3d Correlated Topological Kondo Insulator Candidate FeSb$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Ziling Cao, Jie Pang, Yu Xu, Taimin Miao, Bo Liang, Wenpei Zhu, Neng Cai, Mingkai Xu, Jumin Shi, Yingjie Shu, Yiwen Chen, Jiachen Wang, Shenjin Zhang, Fengfeng Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Zhihai Zhu, Xintong Li, Hanqing Mao, Guodong Liu, Zuyan Xu, Youguo Shi, Lin Zhao, X. J. Zhou
FeSb$ _2$ is a correlated narrow-gap semiconductor that has often been discussed as a $ 3d$ -electron Kondo insulator candidate and exhibits a low-temperature resistance plateau with possible surface-dominated conduction. We carried out a systematic high-resolution laser-based angle-resolved photoemission spectroscopy (ARPES) study of FeSb$ _2$ to investigate its electronic structure. The surface states around the zone center show clear anisotropic splitting. When the temperature is lowered into the resistance plateau regime ($ <6,\mathrm{K}$ ), the surface states remain robust, but their photoemission peaks become much sharper and gain spectral weight. Two distinct flat-band-like features are observed at low energy. One is located at $ \sim$ 127 meV below the Fermi level, which exists only along a specific high-symmetry direction, while the other is located at $ \sim$ 70 meV below the Fermi level and is present along all the measured momentum cuts around the zone center. These results provide new information to understand the renormalization effects, the resistance plateau, and the topological nature of FeSb$ _2$ .
Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 6 figures
Chinese Physics B 35, 097901 (2026)
Scandium diboride: a semi-metallic, lattice, thermally matched substrate for vertical AlGaN power electronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
MVS Chandrashekhar, Daniel Joel Harrison, Ahamed Raihan, Astrid D. Kengne, R. Shipra, Han Xie, Tasnia Jabin, Monte Hendrix, Ethan Scott, Roshan S. Annam, Sharad Mahatara, Evan N. Crites, Allana G. Iwanicki, Luke J. Meiler, Maxime Siegler, Renae N. Gannon, Steven R Spurgeon, Ashutosh Giri, Rajeswari Kolagani, Joshua A. Burrow, Stephan Lany, Patrick Hopkins, Tyrel M. McQueen, Michael Spencer, Satya Khushwaha
We report the properties of hexagonal (space group P6/mmm) scandium diboride ($ \mathrm{ScB}2$ ) single crystals grown by a laser diode floating zone method at growth rates of ~1mm/hr under B-rich conditions with (002) rocking curve widths $ \Delta\omega$ =38’’ approaching the quality of commercial SiC/GaN substrates. Lattice expansion measurements reveal matching to $ \mathrm{Al{0.55}Ga_{0.45}N}$ with a coefficient of thermal expansion ~5ppm/K at typical AlGaN growth temperatures, enabling thick AlGaN layers for ultra-wide bandgap (UWBG) power electronics >1kV. We measure semi-metallic room temperature resistivity ~15$ \mu\Omega$ cm, climbing to ~93$ \mu\Omega$ cm at 773K with a $ T^2$ dependence effectively eliminating substrate parasitic resistance, the limiting factor in exploiting the full potential of UWBG. The Debye temperature $ \theta_{D,ScB_2}$ from heat capacity and lattice expansion is ~850K well matched to $ \theta_{D,ScB_2}$ , but lower than the 1100K measured for Sc-rich growth conditions. We discuss Debye matching as a key substrate codesign criterion providing significant overlap in phonon modes for heat removal and thermal matching during AlGaN growth. The competitive thermal conductivity at room temperature 53W/mK is half that from full first principles calculations, a discrepancy we attribute to the presence of Sc-vacancies generated by B-rich growth. while the resistivity is ~2x the theoretical value, indicating that both electrons and phonons play equal role in thermal transport. The smooth ~2.5nm rms roughness surface enables advanced heat removal modalities through engineered phonon bridges and phonon polaritons in $ \mathrm{ScB}_2$ /AlGaN interfacial heterostructures, potentially allowing ~10-100x increase in power handling over state-of-the-art GaN/SiC.
Materials Science (cond-mat.mtrl-sci)
Quantum-interference-driven orbital density wave and high-temperature superconductivity in trilayer nickelates
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Youichi Yamakawa, Hiroshi Kontani
Intertwined charge-density-wave (CDW) and spin-density-wave (SDW) orders are a hallmark of high-temperature superconducting multilayer nickelates. In trilayer La4Ni3O_{10}, charge correlations develop at temperatures above the onset of long-range spin order, and the characteristic ordering wavevectors satisfy $ Q_{cdw} \approx 2Q_{sdw}$ . Here, using a density-wave equation with vertex corrections, we show that quantum interference between short-range SDW fluctuations at $ q \approx Q_{sdw}$ on the outer NiO2 layers generates an inter-outer-layer bond order at $ Q_{cdw} \approx 2 Q_{sdw}$ . This bond order induces a pronounced inner-layer-centered orbital order, with antiphase modulations of the Ni $ d_{3z^2-r^2}$ and $ d_{x^2-y^2}$ occupations, producing strong orbital polarization but only weak total charge modulation. This intertwined bond-and-orbital order accounts for the layer-selective electronic reconstruction inferred from NMR/NQR and is consistent with Raman spectroscopy and scanning tunnelling microscopy measurements. The same orbital and spin fluctuations also cooperate to stabilize $ s_{\pm}$ -wave superconductivity through $ M_z$ mirror-parity selection rules. Our results provide a unified microscopic framework for intertwined density-wave order and high-Tc superconductivity in multilayer nickelates.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
19 pages, 10 figures
Face-to-face anneal temperature controls lattice parameter in Ta(C,N) virtual substrates for AlGaN power electronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-22 20:00 EDT
Noah Zahn, Julia L. Martin, Michelle A. Smeaton, Renae Gannon, Henry Garland, M. Brooks Tellekamp
Tantalum carbide (TaC) thin film ‘’virtual’’ substrates are a highly desirable material for $ \text{Al}{0.5}\text{Ga}{0.5}\text{N}$ vertical power electronics devices due to lattice matching, thermal expansion matching, and metallic conductivity. However, the material has not been demonstrated to support $ \text{Al}{x}\text{Ga}{1-x}\text{N}$ layers of variable composition $ x$ , limiting the range of device applications. We present a method to achieve tunable rock salt $ \text{Ta}\text{C}{x}\text{N}{1-x}$ virtual substrates via a face-to-face annealing of TaC thin films in an $ \text{N}2$ atmosphere. The results suggest that annealing temperatures below $ 1600,^{\circ}\text{C}$ promote partial uptake of nitrogen onto carbon and anion vacancy sites to form rock salt $ \text{Ta(C,N)}$ with intermediate anion compositions. At temperatures $ \ge 1600,^{\circ}\text{C}$ , nitrogen primarily occupies the anion sublattice and the crystalline quality and surface morphology simultaneously degrade coincident with the formation of secondary phases. This study demonstrates the growth and processing parameters necessary to make tunable lattice constant virtual substrates for $ \text{Al}{x}\text{Ga}_{1-x}\text{N}$ from $ x = 0.5\text{-}1$ , enabling vertically conducting power electronic devices with reduced defect density at high Al-content.
Materials Science (cond-mat.mtrl-sci)
Staged emergence of anomalous Hall transport in a correlated uranium Weyl semimetal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-22 20:00 EDT
Sabin Regmi, Shuxiang Zhou, Chandan K. Singh, Alexei Fedorov, Jonathan Denlinger, Zeyu Ma, Yidi Wang, Jennifer E. Hoffman, Peter M. Oppeneer, Dariusz Kaczorowski, Tomasz Durakiewicz, Krzysztof Gofryk
Understanding how electronic correlations reshape topological states remains a central challenge in quantum materials. Here we investigate the uranium ferromagnet UPS using magnetotransport, angle-resolved photoemission spectroscopy, thermodynamic measurements, and first principles calculations. Resonant photoemission reveals narrow U-$ 5f$ spectral weight at the Fermi level coexisting with broad incoherent states, consistent with the itinerant/localized duality characteristic of uranium $ 5f$ electrons. The anomalous Hall conductivity reaches approximately $ 4.5\times10^{2},\Omega^{-1}\mathrm{cm}^{-1}$ , yet does not simply follow the ordered magnetic moment. Temperature dependent photoemission reveals relatively little change across $ T_C=118$ K, followed by a pronounced redistribution of low-energy $ 5f$ spectral weight below approximately 90K. First-principles calculations identify a symmetry protected Weyl crossing with pronounced Berry curvature and yield an intrinsic anomalous Hall conductivity of approximately $ 9.6\times10^{2},\Omega^{-1}\mathrm{cm}^{-1}$ . These results demonstrate that magnetic order, correlated electronic reconstruction, and anomalous Hall transport develop over distinct but overlapping temperature ranges, revealing how strong correlations reshape topological transport in a uranium Weyl semimetal.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
11 pages, 9 Figures
Channel concentration of critical quantum geometry
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
The quantum metric quantifies the total ground-state response along a parameter direction, but does not resolve how excitations share that response. We define channel concentration (CC) as the sum of squared normalized response weights over specified excitation channels, such as momentum blocks. An exact finite-size theorem yields thermodynamic CCs of 2/3 for the field response of the critical transverse-field Ising model and 1/3 for the half-filled XX pairing response, despite the same leading metric scaling. In finite-size approaches to the XY Lifshitz point, field and anisotropy perturbations yield different concentrations despite a common limiting Hamiltonian with quadratic dispersion. In a unitary 1+1-dimensional conformal field theory (CFT) on a circle, we consider a nondegenerate vacuum in a fixed sector perturbed by one spatially integrated scalar primary. We derive complete zero-momentum energy-level response weights, including descendants. For scaling dimension $ 0<\Delta<3/2$ , these weights determine the normalized response distribution and an exact universal concentration function. The expression reproduces the exact Ising lattice limit 2/3 and gives approximately 0.8515 for the three-state Potts thermal field, compared with approximately 0.800 from an exponent-only approximation. Finite-size interacting calculations compare concentrations and ranked response weights over many-body energy levels. These exact benchmarks show which response distinctions total metric scaling misses and guide comparisons with finite-size interacting spectra.
Statistical Mechanics (cond-mat.stat-mech)
44 pages, 7 figures (including Supplemental Material); code and data available at this https URL
Nucleosome simulations suggest mechanisms of electrostatically-driven mesoscale chromatin evolution
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-22 20:00 EDT
Nucleosomes are structures made up of proteins called histones that bind and compact DNA, driving the mesoscale organization of the chromatin polymer. Although histone proteins have diversified over evolutionary time, their contributions to the corresponding diversification of chromatin structure are poorly understood. Here, we mine protein databases for histones and create \emph{in silico} nucleosomes for 3241 organisms spanning $ >$ 1.5B years of evolution. Using a combination of electrostatic calculations and coarse-grained molecular dynamics simulations, we reveal extensive biophysical diversification of the nucleosome unit. Finally, we perform coarse-grained oligonucleosomal simulations on a subset of evolutionarily and biophysically divergent nucleosomes, demonstrating dramatic differences in bulk phase behavior of chromatin. Taken together, our results suggest a paradigm in which histones may have evolved to facilitate particular types of mesoscale chromatin behavior.
Soft Condensed Matter (cond-mat.soft), Biomolecules (q-bio.BM)
working paper
Modified Low-Temperature Scanning Tunneling Microscope for Ultrafast Pump-Probe Spectroscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Vibhuti N. Rai, Junyoung Sim, Nils Bogdanoff, Sergey Trishin, Florian Faaber, Paul Wiechers, Caroline Firschke, Tobias Kampfrath, Christian Lotze, Katharina J. Franke
Combining scanning tunneling microscopy (STM) with terahertz pulses (THz-STM) enables ultrafast dynamics of phonons, spins, and charge carriers to be probed with atomic-scale spatial and sub-picosecond temporal resolution. However, coupling THz radiation into a low-temperature STM junction presents some technical challenges as it requires optical access for laser illumination while maintaining junction stability. Instead of designing a completely new STM head with customized optical access and optics within the ultra-high vacuum chamber, we modified a Besocke “Beetle” style STM with minimal changes of the cryogenic radiation shields. Despite the given geometrical conditions, we achieved efficient coupling of THz and optical pulses to the STM junction while maintaining temperatures below 6 K. We designed the optical setup on a separate laser table, starting with femtosecond laser pulses that are used to generate THz pulses in a LiNbO$ _3$ crystal. We show the obtained THz pulse shapes and determine the effective time resolution using cross-correlation measurements. We further demonstrate the stable performance of the modified STM by measuring THz-induced tunneling currents from monolayer molybdenum disulfide (MoS$ _2$ ) grown on Au(111). The resulting current maps resolve atomic-scale contrast revealing a point defect. The measurements confirm efficient THz coupling and stable low-temperature STM operation with atomic resolution.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 7 figures
Model of the magnon Kerr effect in a highly anisotropic ferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
Davit Petrosyan, Hiroki Matsumoto, Hanchen Wang, Richard Schlitz, Pietro Gambardella, William Legrand
The magnon Kerr effect is a nonlinear phenomenon that occurs universally in any ferromagnet with finite magnetic anisotropy. It manifests itself as a magnon population-dependent change in the magnon dispersion relation. Here, we derive the Hamiltonian for the magnon Kerr effect for a thin film with uniaxial anisotropy. We consider the external field, parallel, perpendicular, and at an intermediate angle to the anisotropy axis, and determine the Kerr coefficient in each case. We show how the nonlinearity scales for different magnetic materials as a function of magnon frequency and magnetic sample volume. Moreover, we derive the equations of motion for a hybrid cavity-magnon system with such thin-film magnon Kerr nonlinearity, to obtain populations of photons and magnons, and scattering matrix terms for the microwave transmission of the cavity, relevant for experimental observations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 9 figures
Collective Coordinate Dynamics of Antiferromagnet: Gravity by Quantum Metric
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-22 20:00 EDT
The collective coordinate dynamics of antiferromagnetic and ferrimagnetic textures emerges as a geodesic equation governed by the quantum geometry of the CP$ ^1$ state associated with the Néel vector, rendering an effective Riemannian gravity and a Lorentz force in the texture motion. This unveils a physical scenario fundamentally distinct from the Thiele equation widely used for ferromagnetic textures, which is inertialess without any gravity analogy. Applying our framework to an optically driven ultrafast antiferromagnetic domain wall, we can explain the helicity-dependent asymmetric motion observed experimentally and predict a vibrantly breathing wall width.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Quantum Mpemba effect from Stark localization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-22 20:00 EDT
Nico Albert, Masudul Haque, Shovan Dutta
In classical systems, rugged potential energy landscapes provide a transparent mechanism for the celebrated Mpemba effect, in which hotter initial states cool down faster. This picture generally does not survive in quantum systems. Here we show how to design a quantum energy landscape with local dissipation leading to an Mpemba effect with parametrically separated timescales. Our approach uses Stark localization to design an energy landscape and localized incoherent hopping as cooling mechanism. The hops are triggered by rare “detection” events whose rate grows with energy, allowing hotter states to cool faster and producing super-exponentially separated cooling rates for localized initial states. We further show that the effect is dramatically enhanced by collective hopping of bound pairs in the presence of attractive on-site interactions. These findings have clear experimental signatures accessible in present-day setups.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)