CMP Journal 2025-08-29
Statistics
Physical Review Letters: 10
Physical Review X: 2
arXiv: 67
Physical Review Letters
Quantum Bayes’ Rule and Petz Transpose Map from the Minimum Change Principle
Research article | Optimization problems | 2025-08-28 06:00 EDT
Ge Bai, Francesco Buscemi, and Valerio Scarani
Bayes’ rule, which is routinely used to update beliefs based on new evidence, can be derived from a principle of minimum change. This principle states that updated beliefs must be consistent with new data, while deviating minimally from the prior belief. Here, we introduce a quantum analog of the minimum change principle and use it to derive a quantum Bayes’ rule by minimizing the change between two quantum input-output processes, not just their marginals. This is analogous to the classical case, where Bayes’ rule is obtained by minimizing several distances between the joint input-output distributions. When the change maximizes the fidelity, the quantum minimum change principle has a unique solution, and the resulting quantum Bayes’ rule recovers the Petz transpose map in many cases.
Phys. Rev. Lett. 135, 090203 (2025)
Optimization problems, Quantum foundations, Quantum information theory, Stochastic inference
Equation of State of Decompressed Quark Matter, and Observational Signatures of Quark-Star Mergers
Research article | Nuclear astrophysics | 2025-08-28 06:00 EDT
Zhiqiang Miao, Zhenyu Zhu, and Dong Lai
Quark stars are challenging to confirm or exclude observationally because they can have similar masses and radii as neutron stars. By performing the first calculation of the nonequilibrium equation of state of decompressed quark matter at finite temperature, we determine the properties of the ejecta from binary quark-star or quark star–black hole mergers. We account for all relevant physical processes during the ejecta evolution, including quark nugget evaporation and cooling, and weak interactions. We find that these merger ejecta can differ significantly from those in neutron star mergers, depending on the binding energy of quark matter. For relatively high binding energies, quark star mergers are unlikely to produce $r$-process elements and kilonova signals. We propose that future observations of binary mergers and kilonovae could impose stringent constraints on the binding energy of quark matter and the existence of quark stars.
Phys. Rev. Lett. 135, 091402 (2025)
Nuclear astrophysics, Quark matter, Binary stars, Neutron stars & pulsars
Quasinormal Modes of Nonthermal Fixed Points
Research article | Gauge-gravity dualities | 2025-08-28 06:00 EDT
Matisse De Lescluze and Michal P. Heller
Quasinormal modes play a prominent role in the relaxation of diverse physical systems to equilibria, ranging from astrophysical black holes to tiny droplets of quark-gluon plasma at the RHIC and LHC accelerators. We propose that a novel kind of quasinormal mode governs the direct approach to self-similar time evolution of nonthermal fixed points, whose relevance ranges from high-energy physics to cold atom gases. We utilize black hole perturbation theory techniques to compute the spectrum of these far-from-equilibrium quasinormal modes for a kinetic theory with a Fokker-Planck collision kernel in isotropic and homogeneous states. Our conclusion is that quasinormal modes of nonthermal fixed points give rise to a tower of progressively more decaying power-law contributions. A by-product of our analysis is a precise determination and improved understanding of the distribution function characterizing nonthermal fixed points.
Phys. Rev. Lett. 135, 091601 (2025)
Gauge-gravity dualities, Kinetic theory, Quantum field theory, Ultracold gases
Longitudinal Short-Distance Constraints on Hadronic Light-by-Light Scattering and Tensor-Meson Contributions to the Muon $g- 2$
Research article | Form factors | 2025-08-28 06:00 EDT
Jonas Mager, Luigi Cappiello, Josef Leutgeb, and Anton Rebhan
A holographic-QCD-based ansatz suggests that the contribution from a tower of tensor mesons could explain why the values of muon g-2 from the dispersive analysis and lattice QCD differ.
Phys. Rev. Lett. 135, 091901 (2025)
Form factors, Gauge-gravity dualities, Particle interactions, Quantum chromodynamics, Strong interaction, Mesons, Muons, Photons, Magnetic moment
Finding the Ultranarrow ${^{3}P}{2}\rightarrow {^{3}P}{0}$ Electric Quadrupole Transition in ${\mathrm{Ni}}^{12+}$ Ion for an Optical Clock
Research article | Atomic, optical & lattice clocks | 2025-08-28 06:00 EDT
Charles Cheung, Sergey G. Porsev, Dmytro Filin, Marianna S. Safronova, Malte Wehrheim, Lukas J. Spieß, Shuying Chen, Alexander Wilzewski, José R. Crespo López-Urrutia, and Piet O. Schmidt
A novel hybrid approach calculates the frequency of a strongly forbidden clock transition in a highly charged ion.
Phys. Rev. Lett. 135, 093002 (2025)
Atomic, optical & lattice clocks, Ions, High-throughput calculations
Probing $\mathbit{k}$-Space Alternating Spin Polarization via the Anomalous Hall Effect
Research article | Altermagnetism | 2025-08-28 06:00 EDT
Rui Chen, Zi-Ming Wang, Ke Wu, Hai-Peng Sun, Bin Zhou, Rui Wang, and Dong-Hui Xu
Altermagnets represent a recently discovered class of collinear magnets, characterized by antiparallel neighboring magnetic moments and an alternating-sign spin polarization in momentum space ($\mathbit{k}$ space). However, experimental methods for probing the $\mathbit{k}$-space spin polarization in altermagnets remain limited. In this Letter, we propose an approach to address this challenge by interfacing an altermagnet with the surface of a topological insulator. We show that the altermagnet’s unique $\mathbit{k}$-space spin polarization imprints a momentum-dependent, sign-alternating Dirac mass onto the otherwise massless surface states of the topological insulator, a direct consequence of breaking time-reversal symmetry. This engineered Dirac mass results in a unique, alternating half-quantized anomalous Hall effect. By measuring the Hall conductance, we can extract the local $\mathbit{k}$-space magnetic moment. Moreover, we can map the global magnetic moment distribution by tuning the Dirac point position using an in-plane magnetic field, thereby revealing the $\mathbit{k}$-space spin density of the altermagnet. This Letter establishes the Dirac fermion on the topological insulator surface as a sensitive probe for unveiling spin characters of altermagnets and those of other unconventional antiferromagnets.
Phys. Rev. Lett. 135, 096602 (2025)
Altermagnetism, Anomalous Hall effect, Dilute magnetic topological insulators, Magnetic order, Magnetic texture, Topological Hall effect, Altermagnets, Topological materials
Robustness of Vacancy-Bound Non-Abelian Anyons in the Kitaev Model in a Magnetic Field
Research article | Anyons | 2025-08-28 06:00 EDT
Bo Xiao, Gonzalo Alvarez, and Gábor B. Halász
Non-Abelian anyons in quantum spin liquids (QSLs) provide a promising route to fault-tolerant topological quantum computation. In the exactly solvable Kitaev honeycomb model, such anyons of the QSL state can be bound to nonmagnetic spin vacancies and endowed with non-Abelian statistics by an infinitesimal magnetic field. Here, we investigate how this approach for stabilizing non-Abelian anyons extends to a finite magnetic field represented by a proper Zeeman term. Through large-scale density-matrix renormalization group simulations, we compute the vacancy-anyon binding energy as a function of magnetic field for both the ferromagnetic and antiferromagnetic Kitaev models. We find that anyon binding remains robust within the entire QSL phase for the ferromagnetic Kitaev model but breaks down already inside this phase for the antiferromagnetic Kitaev model. To compute a binding energy several orders of magnitude below the magnetic energy scale, we introduce both a refined definition and an extrapolation scheme based on carefully tailored perturbations.
Phys. Rev. Lett. 135, 096603 (2025)
Anyons, Non-Abelian gauge theories, Quantum spin liquid, Topological phases of matter, Topological quantum computing, Topological materials, Density matrix renormalization group
Electrical Control of Ultrafast Magnetic Speeds in Graphene Spin Field-Effect Junctions
Research article | Spin dynamics | 2025-08-28 06:00 EDT
David Muradas-Belinchón, Suchetana Mukhopadhyay, Francesco Foggetti, Surya N. Panda, Olof Karis, Peter M. Oppeneer, Anjan Barman, and M. Venkata Kamalakar
Graphene spin field-effect junctions for electric-field control of ultrafast spin dynamics tune magnetic speeds in spintronic devices.
Phys. Rev. Lett. 135, 097001 (2025)
Spin dynamics, Ultrafast demagnetization, Ultrafast phenomena, Graphene
Optimal Control of Levitated Nanoparticles through Finite-Stiffness Confinement
Research article | Brownian motion | 2025-08-28 06:00 EDT
Marco Baldovin, Ines Ben Yedder, Carlos A. Plata, Damien Raynal, Loïc Rondin, Emmanuel Trizac, and Antonio Prados
Optimal control of levitated nanoparticles subjected to thermal fluctuations is a challenging problem, both theoretically and experimentally. In this Letter, we compute the time-dependent harmonic confining potential that steers, in a prescribed time and with the minimum energetic cost, a Brownian particle between two assigned equilibrium states. We take full account of inertial effects, thus addressing the general underdamped dynamics, and, to address actual experimental conditions, the stiffness of the confining potential is required to be bounded. We carry out an experiment realizing the described protocol for an optically confined nanoparticle, which is shown to reach the target state within accuracy—while spending less energy than other protocols with the same duration, significantly shorter than the characteristic relaxation time. The results presented here are expected to have relevant applications in the design of optimal devices, such as engines at the nanoscale.
Phys. Rev. Lett. 135, 097102 (2025)
Brownian motion, Optimization problems, Stochastic thermodynamics, Nanoparticles
Flow-Driven Stretch Fluctuations Govern the Nonlinear Viscoelasticity of Elongating Associative Polymer Networks
Research article | Biomimetic & bio-inspired materials | 2025-08-28 06:00 EDT
Songyue Liu and Thomas C. O’Connor
Associative polymer networks exhibit broad stretch fluctuations under elongational flow, leading to a rate-dependent viscosity.
Phys. Rev. Lett. 135, 098101 (2025)
Biomimetic & bio-inspired materials, Non-Newtonian fluids, Polymer conformation changes, Rheology
Physical Review X
Dynamical Scaling Reveals Topological Defects and Anomalous Evolution of a Photoinduced Phase Transition
Research article | Charge density waves | 2025-08-28 06:00 EDT
Gal Orenstein, Ryan A. Duncan, Gilberto A. de la Peña Muñoz, Yijing Huang, Viktor Krapivin, Quynh Le Nguyen, Samuel Teitelbaum, Anisha G. Singh, Roman Mankowsky, Henrik Lemke, Mathias Sander, Yunpei Deng, Christopher Arrell, Ian R. Fisher, David A. Reis, and Mariano Trigo
Ultrafast x-ray scattering reveals that light-excited charge density waves in LaTe3 relax slowly due to vortexlike topological defects, showing glasslike behavior and subdiffusive dynamics at the nanoscale.
Phys. Rev. X 15, 031058 (2025)
Charge density waves, Order parameters, Phase transitions, Photoinduced effect, Topological defects, Ultrafast femtosecond pump probe, X-ray diffuse scattering
Berry Phase Dynamics of Sliding Electron Crystals
Research article | Anomalous Hall effect | 2025-08-28 06:00 EDT
Yongxin Zeng and Andrew J. Millis
Sliding electron crystals acquire a transverse velocity under an electric field because of nontrivial quantum geometry, breaking Galilean invariance and altering Hall conductance in materials like rhombohedral graphene.
Phys. Rev. X 15, 031059 (2025)
Anomalous Hall effect, Transport phenomena, Chern insulators, Wigner crystal
arXiv
Sub-Nanometer Interfacial Hydrodynamics: The Interplay of Interfacial Viscosity and Surface Friction
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-29 20:00 EDT
Shane R. Carlson, Roland R. Netz
For an accurate description of nanofluidic systems, it is crucial to account for the transport properties of liquids at surfaces on sub-nanometer scales, where classical hydrodynamics fails due to the finite range of surface-liquid interactions and modifications of the local viscosity. We show how to account for both via generalized, position-dependent surface-friction and interfacial viscosity profiles, which enables the accurate description of interfacial flow on the nanoscale using the Stokes equation. Such profiles are extracted from non-equilibrium molecular dynamics simulations of water on polar, non-polar, fluorinated, and unfluorinated alkane and alcohol self-assembled monolayers of widely varying wetting characteristics. Power-law relationships among the Navier friction coefficient, interfacial viscosity excess, and depletion length are revealed, and these are each found to be exponential in the work of adhesion. Our framework forms the basis for describing sub-nanometer fluid flow at interfaces with implications for electrokinetics, biophysics, and nanofluidics.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph), Fluid Dynamics (physics.flu-dyn)
31 Pages, 19 Figures, Submitted to Nano Letters on July 31, 2025
Qubit parametrization of the variational discrete action theory for the multiorbital Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Zhengqian Cheng, Chris A. Marianetti
The variational discrete action theory (VDAT) at \mathcal{N}=3 is a potent tool for accurately capturing Mott and Hund physics at zero temperature in d=\infty at a cost comparable to the Gutzwiller approximation, which is recovered by VDAT at \mathcal{N}=2. Here we develop a qubit parametrization of the gauge constrained algorithm of VDAT at \mathcal{N}=3 for the multiorbital Hubbard model with general density-density interactions. The qubit parametrization yields an explicit variational trial energy, and the variational parameters consist of the momentum density distribution, the shape of a reference fermi surface, and the pure state of a qubit system with dimension of the local Hilbert space. To illustrate the power of the qubit parametrization, we solve for the ground state properties of the multiorbital Hubbard model with Hund coupling for local orbital number N_{orb}=2-7. A Taylor series expansion of the partially optimized trial energy is used to explain how the Hund’s coupling changes the order of the Mott transition. For the case of the SU(2N_{orb}) Hubbard model, an explicit approach for computing the critical U_{c} for the Mott transition is provided, yielding an analytical expression for U_{c} in the large N_{orb} limit. Additionally, we provide an analytical solution for the ground state properties of the single band Hubbard model with a special density of states. Finally, we demonstrate that the qubit parametrization can also be applied to \mathcal{N}=2, for both G-type and B-type variants, where the G-type yields an identical expression to the slave spin mean-field theory. The qubit parametrization not only improves the efficiency and transparency of VDAT at \mathcal{N}=3, but also provides the key advances for the construction of a one-body reduced density matrix functional capable of capturing Mott and Hund physics.
Strongly Correlated Electrons (cond-mat.str-el)
Experimental observation of multimode quantum phase transitions in a superconducting Bose-Hubbard simulator
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Claudia Castillo-Moreno, Théo Sépulcre, Timo Hillmann, Kazi Rafsanjani Amin, Mikael Kervinen, Simone Gasparinetti
The study of phase transitions and critical phenomena arising in quantum driven-dissipative systems, and whether a correspondence can be drawn to their equilibrium counterparts, is a pressing question in contemporary physics. The development of large-scale superconducting circuits provides an experimental platform for these theoretical models. We report an experimental study of a multi-mode dissipative first-order phase transition in a 1D Bose-Hubbard chain consisting of 21 superconducting resonators. This phase transition manifests itself as a simultaneous frequency jump in all resonator modes as the frequency or power of a pump tone is swept. By measuring the system’s emission spectrum through the transition, we characterize the dim-to-bright phase transition and construct the full phase diagram. We further perform time-dependent measurements of the switching between the two phases in the transition region, from which we corroborate the transition line and extract transition times ranging from a few ms up to 143~s. Our model, based on single-mode mean-field theory and cross-Kerr interactions, captures the features at moderate pump powers and quantitatively reproduces the transition line. Our results open a new window into non-equilibrium quantum many-body physics and mark a step toward realizing and understanding dissipative phase transitions in the thermodynamic limit using superconducting quantum circuits.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
14 pages, 9 figures
MicroLad: 2D-to-3D Microstructure Reconstruction and Generation via Latent Diffusion and Score Distillation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
A major obstacle to establishing reliable structure-property (SP) linkages in materials engineering is the scarcity of diverse 3D microstructure datasets. Limited dataset availability and insufficient control over the analysis and design space restrict the variety of achievable microstructure morphologies, hindering progress in solving the inverse (property-to-structure) design problem. To address these challenges, we introduce MicroLad, a latent diffusion framework specifically designed for reconstructing 3D microstructures from 2D data. Trained on 2D images and employing multi-plane denoising diffusion sampling in the latent space, the framework reliably generates stable and coherent 3D volumes that remain statistically consistent with the original data. While this reconstruction capability enables dimensionality expansion (2D-to-3D) for generating statistically equivalent 3D samples from 2D data, effective exploration of microstructure design requires methods to guide the generation process toward specific objectives. To achieve this, MicroLad integrates score distillation sampling (SDS), which combines a differentiable score loss with microstructural descriptor-matching and property-alignment terms. This approach updates encoded 2D slices of the 3D volume in the latent space, enabling robust inverse-controlled 2D-to-3D microstructure generation. Consequently, the method facilitates exploration of an expanded 3D microstructure analysis and design space in terms of both microstructural descriptors and material properties.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Revealing degradation mechanisms in YSZ ceramics through machine learning-guided aging and multiscale characterization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Prachi Garg, Baishakhi Mazumder
The long-term performance of yttria-stabilized zirconia (YSZ) based energy and biomedical devices is compromised by low-temperature degradation (LTD). This study presents a novel integration of machine learning-guided hydrothermal aging with multiscale characterization to resolve a two-stage degradation mechanism in 3 mol% YSZ. Stage 1 (0 to 30 hrs) features initial surface relief building, which transitions to partial refinement and relief distribution in stage 2 (30 to 60 hrs), alongside a rise in monoclinic phase content. The evolving microstructure increases triple-junction grain boundary density, and these junctions act as degradation hotspots, where vacancy exchange and water access accelerate the transformation. These findings highlight grain boundary chemistry, rather than grain size alone, as a key LTD driver, suggesting boundary engineering as a strategy to enhance YSZ stability for energy, biomedical, and thermal applications.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Supplementary information is provided at the end of the manuscript
Probing disorder-driven topological phase transitions via topological edge modes with ultracold atoms in Floquet-engineered honeycomb lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Alexander Hesse, Johannes Arceri, Moritz Hornung, Christoph Braun, Monika Aidelsburger
One of the most fascinating properties of topological phases of matter is their robustness to disorder and imperfections. Although several experimental techniques have been developed to probe the geometric properties of engineered topological Bloch bands with cold atoms, they almost exclusively rely on the translational invariance of the underlying lattice. This prevents direct studies of topology in the presence of disorder, further hindering an extension to disordered interacting topological phases. Here, we identify disorder-driven phase transitions between two distinct Floquet topological phases using the characteristic properties of topological edge modes with ultracold atoms in periodically-driven two-dimensional (2D) optical lattices. Our results constitute an important step towards studying the rich interplay between topology and disorder with cold atoms. Moreover, our measurements confirm that disorder indeed favors the anomalous Floquet topological regime over conventional Hall systems, indicating an enhanced robustness and paving the way towards observing exotic out-of-equilibrium phases such as the anomalous Floquet Anderson insulator.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Nonlinear Hall effect in topological Dirac semimetals in parallel magnetic field
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Maxim Dzero, Maxim Khodas, Alex Levchenko, Vladyslav Kozii
We compute the second-harmonic response of two-dimensional topological Dirac semimetals subjected to an external in-plane magnetic field. The quantum kinetic equation for the Wigner distribution function is derived and then solved to evaluate the second-order electric-field contributions to the current density. Both the Berry curvature dipole and the field-induced terms in the current are analyzed across a broad range of model parameters. We propose that our theory can be tested experimentally by measuring the dependence of the anomalous Hall resistivity on the in-plane magnetic field in the surface states of the topological insulator SnTe, in WTe$ _2$ and WSe$ _2$ monolayers, as well as in the Kondo lattice material Ce$ _3$ Bi$ _4$ Pd$ _3$ at very low temperatures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 4 figures
Extended s-wave altermagnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Matteo Dürrnagel, Lennart Klebl, Tobias Müller, Ronny Thomale, Michael Klett
We propose extended s-wave altermagnets (sAMs) as a class of magnetic states which are fully gapped, spin-compensated, and feature spin-polarized bands. sAMs are formed through valley-exchange symmetries, which act as momentum-space translations beyond standard crystallographic spin-group classifications. Using an effective two-valley model, we demonstrate that sAMs exhibit isotropic spin splitting, enable spin-selective transport in tailored heterostructures, and give rise to descendant pair density wave order. From a microscopic sAM minimal model, we develop the guiding principles to identify sAMs in quantum magnets.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 3 figures, Supplemental Material
Critical quantum liquids and the cuprate high temperature superconductors
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Pietro M. Bonetti, Maine Christos, Alexander Nikolaenko, Aavishkar A. Patel, Subir Sachdev
We present a theoretical framework for the cuprate superconductors, rooted in a fractionalized Fermi liquid (FL\ast) description of the intermediate-temperature pseudogap phase at low doping. The FL\ast theory predicted hole pockets each of fractional area $ p/8$ at hole doping $ p$ , in contrast to the area $ p/4$ in a spin density wave state or its thermal fluctuation. A recent magnetotransport observation of the Yamaji angle is in good agreement with area $ p/8$ .
We review a theory for the FL\ast phase of a single-band model using a pair of ancilla qubits on each site. Its mean field theory yields hole pockets of area $ p/8$ , and matches the gapped photoemission spectrum in the anti-nodal region of the Brillouin zone. Fluctuations are described by the SU(2) gauge theory of a background spin liquid with critical Dirac spinons. A Monte Carlo study of the thermal SU(2) gauge theory transforms the hole pockets into Fermi arcs. One route to confinement upon lowering temperature yields a $ d$ -wave superconductor via a Kosterlitz-Thouless transition of $ h/(2e)$ vortices, with nodal Bogoliubov quasiparticles featuring anisotropic velocities and vortices surrounded by charge order halos. An alternative route produces a charge-ordered metallic state that exhibits quantum oscillations in agreement with experimental data.
Increasing doping from the FL\ast phase drives a transition to a conventional Fermi liquid at large doping, passing through an intermediate strange metal regime. We formulate a theory of this metal using a critical quantum `charge’ liquid of mobile electrons in the presence of disorder, developed via an extension of the Sachdev-Ye-Kitaev model.
At low temperatures, and across optimal and over doping, we address the regimes of extended non-Fermi liquid behavior by Griffiths effects near quantum phase transitions in disordered metals.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
90 pages, 43 figures. Review article based on lectures by SS at Boulder, Trieste, Hong Kong, with links to lecture videos. Comments welcome
Bosonization and Kramers-Wannier dualities in general dimensions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
It is well known that the noninteracting Majorana chain is dual to the one-dimensional transverse-field Ising model, either through the Jordan-Wigner transformation or by gauging fermion parity. In this correspondence, the minimal translation of the Majorana chain maps to the celebrated Kramers-Wannier (KW) duality of the spin model, with the critical point mapped to the self-dual point. In this work, we generalize this mapping to two and higher dimensions by constructing a unitary equivalence between the parity-gauged fermionic system and a spin system defined on arbitrary polyhedral decompositions of space. Imposing the flatness condition on the gauge field yields a bosonization duality between the original (ungauged) fermionic system and a gauged spin system obeying a Gauss law. The dependence of the Gauss law in the spin system on the Kasteleyn orientation (and the discrete spin structure) of the fermionic system is made explicit. Applying this bosonization to one or two copies of Majorana fermions on translationally invariant lattices, we derive higher-dimensional analogs of KW (self-)dualities in spin systems arising from fermionic minimal translations. The KW (self-)dualities are non-invertible due to projections onto eigenspaces of higher-form symmetries in the associated symmetry operators. The bosonization framework we present is intuitive, general, and systematic, encompassing other known exact bosonization methods while offering a novel approach to establish new connections between fermionic and spin systems in arbitrary dimensions.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
30 pages, 15 figures
$su(2)$ symmetry of XX spin chains
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Nicolas Crampé, Rafael I. Nepomechie, Luc Vinet, Nabi Zare Harofteh
We show that, after suitably adjusting a uniform transverse magnetic field, the generic inhomogeneous open XX spin chain has a two-fold degeneracy, and an exact $ su(2)$ symmetry whose “inhomogeneous” generators depend on coefficients that can be explicitly computed for models associated with discrete orthogonal polynomials.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
7 pages
Insulating ground state and 2-k magnetic structure of candidate Weyl Hydrogen atom K$_2$Mn$_3$(AsO$_4$)$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Keith M. Taddei, Kulugammana G. S. Ranmohotti, Duminda S. Liurukara, Alex Martinson, Stuart Calder, German Samolyuk, Nabaraj Pokhrel, Daniel Phelan, David Parker
The ideal Weyl ‘Hydrogen-atom’ semi-metal exhibits only a single pair of Weyl nodes and no other trivial states at the Fermi energy. Such a material would be a panacea in the study of Weyl quasi particles allowing direct unambiguous observation of their topological properties. The alluaudite-like K$ _2$ Mn$ _3$ (AsO$ _4$ )$ _3$ compound was recently proposed as such a material. Here we use comprehensive experimental work and first principle calculations to assess this prediction. We find K$ _2$ Mn$ _3$ (AsO$ _4$ )$ _3$ crystallizes in the $ C2/c$ symmetry with a quasi-1D Mn sublattice, growing as small needle-like crystals. Bulk properties measurements reveal magnetic transitions at $ \approx$ 8 and $ \approx$ 4 K which neutron scattering experiments show correspond to two distinct magnetic orders, first a partially ordered ferrimagnetic $ \mathbf{k_1}$ = (0, 0, 0) structure at 8 K and a second transition of $ \mathbf{k_2}$ = (1, 0, 0) at 4 K to a fully ordered state. Below the second transition, both ordering vectors are necessary to describe the complex magnetic structure with modulated spin magnitudes. Both of the best-fit magnetic structures in this work are found to break the symmetry necessary for the generation of the Weyl nodes, though one of the magnetic structures allowed by $ \mathbf{k_1}$ does preserve this symmetry. However, the crystals are optically transparent and ellipsometry measurements reveal a large band-gap, undermining expectations of semi-metallic behavior. Density functional theory calculations predict an insulating antiferromagnetic ground state, in contrast to previous reports, and suggest potential frustration on the magnetic sublattice. Given the wide tunability of the alluaudite structure we consider ways to push the system closer to semi-metallic state.
Strongly Correlated Electrons (cond-mat.str-el)
14 pages, 7 figures
Long-range spatial extension of exciton states in van der Waals heterostructure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Zhiwen Zhou, E. A. Szwed, W. J. Brunner, H. Henstridge, L. H. Fowler-Gerace, L. V. Butov
Narrow lines in photoluminescence (PL) spectra of excitons are characteristic of low-dimensional semiconductors. These lines correspond to the emission of exciton states in local minima of a potential energy landscape formed by fluctuations of the local exciton environment in the heterostructure. The spatial extension of such states was in the nanometer range. In this work, we present studies of narrow lines in PL spectra of spatially indirect excitons (IXs) in a MoSe$ _2$ /WSe$ _2$ van der Waals heterostructure. The narrow lines vanish with increasing IX density. The disappearance of narrow lines correlates with the onset of IX transport, indicating that the narrow lines correspond to localized exciton states. The narrow lines extend over distances reaching several micrometers and over areas reaching ca. ten percent of the sample area. This macroscopic spatial extension of the exciton states, corresponding to the narrow lines, indicates a deviation of the exciton energy landscape from random potential and shows that the excitons are confined in moiré potential with a weak disorder.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Strong Raman Optical Activity and Chiral Phonons in Chiral Hybrid Organic-Inorganic Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Evan W. Muller, Aleksey Ruditskiy, Jie Jiang, Thuc T. Mai, Katherine Burzynski, Ruth Pachter, Michael F. Durstock, W. Joshua Kennedy, Rahul Rao
Hybrid organic-inorganic perovskites with chiral organic cations are very interesting for optoelectronic applications because of their intrinsically chiral light-matter interactions. Chiral distortions in these materials lead to circular dichroism, circular birefringence, and circularly polarized luminescence in the band transitions of the inorganic sublattice. Raman-active vibrational modes in these crystals are governed by crystal symmetry and therefore are also strongly impacted by the nature and magnitude of the chiral distortions. Here, we report low-frequency Raman modes that are sensitive to circularly polarized excitation in chiral hybrid organic-inorganic perovskites (CHOIPs) across a wide range of structures and compositions. The circularly polarized Raman spectra from enantiomers of CHOIP single crystals exhibit sharp modes below 150 cm-1, corresponding to vibrations of the lead iodide octahedra. These modes exhibit strong differences in intensities (Raman optical activity, ROA) depending on the handedness of the excitation, with high degree of polarization for several modes. Calculations reveal the presence of several chiral phonon modes with opposite phonon angular momenta. The strong ROA and the chiral phonon modes are a direct consequence of chirality transfer from the chiral organic linker to the lead iodide octahedra in the CHOIP structure, resulting in a strong chiroptical response in the phonon modes.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
6 Figures
When Dephasing Fails: Thermodynamic Consequences of Decoherence Models in Quantum Transport
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Eren Erdogan, Justin P. Bergfield
Understanding how decoherence influences heat and information flow is essential for realizing the promise of quantum technologies. Two widely used models for incorporating decoherence in quantum transport are the voltage probe (VP), which imposes local charge current conservation, and the voltage-temperature probe (VTP), which also conserves heat current. Although these models are often treated as functionally equivalent, we demonstrate that this equivalence actually exists only under highly symmetric conditions, which may be challenging to achieve experimentally Under asymmetric coupling or thermal bias, the VTP respects thermodynamic constraints and enforces decoherence in both charge and heat channels, while the VP instead acts as a source or sink of heat. Strikingly, the VP can fail to model decoherence in the heat transport entirely, even with large probe coupling strengths. Using a benzene-based molecular junction as a realistic example, we show that these effects significantly impact the predicted heat transport. These results establish that the VP and VTP models are not interchangeable: only the VTP provides a thermodynamically consistent framework for modeling decoherence in quantum transport.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 6 figures
Machine learning topological defect formation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Fumika Suzuki, Ying Wai Li, Wojciech H. Zurek
According to the Kibble-Zurek mechanism (KZM), the density of topological defects created during a second-order phase transition is determined by the correlation length at the freeze-out time. This suggests that the final configuration of topological defects in such a transition is largely established during the impulse regime, soon after the critical point is traversed. Motivated by this, we conjecture that machine learning (ML) can predict the final configuration of topological defects based on the time evolution of the order parameter over a short interval in the vicinity of the critical point, well before the order parameter settles into the emerging new minima resulting from spontaneous symmetry breaking. Furthermore, we show that the predictability of ML also follows the power law scaling dictated by KZM. We demonstrate these using a Recurrent Neural Network.
Statistical Mechanics (cond-mat.stat-mech), General Relativity and Quantum Cosmology (gr-qc), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Computational Physics (physics.comp-ph)
7 pages, 5 figures
Atomistic understanding of hydrogen bubble-induced embrittlement in tungsten enabled by machine learning molecular dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Yu Bao, Keke Song, Jiahui Liu, Yanzhou Wang, Yifei Ning, Penghua Ying, Ping Qian
Hydrogen bubble formation within nanoscale voids is a critical mechanism underlying the embrittlement of metallic materials, yet its atomistic origins remains elusive. Here, we present an accurate and transferable machine-learned potential (MLP) for the tungsten-hydrogen binary system within the neuroevolution potential (NEP) framework, trained through active learning on extensive density functional theory data. The developed NEP-WH model reproduces a wide range of lattice and defect properties in tungsten systems, as well as hydrogen solubility, with near first-principles accuracy, while retaining the efficiency of empirical potentials. Crucially, it is the first MLP capable of capturing hydrogen trapping and H\textsubscript{2} formation in nanovoids, with quantitative fidelity. Large-scale machine-learning molecular dynamics simulations reveal a distinct aggregation pathway where planar hydrogen clusters nucleate and grow along {100} planes near voids, with hexagonal close-packed structures emerging at their intersections. Under uniaxial tension, these aggregates promote bubble fracture and the development of regular {100} cracks, suppressing dislocation activity and resulting in brittle fracture behavior. This work provides detailed atomistic insights into hydrogen bubble evolution and fracture in nanovoids, enables predictive modeling of structural degradation in extreme environments, and advances fundamental understanding of hydrogen-induced damage in structural metals.
Materials Science (cond-mat.mtrl-sci)
14pages,7 figures
Quantum Interference Supernodes, Thermoelectric Enhancement, and the Role of Dephasing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Quantum interference (QI) can strongly enhance thermoelectric response, with higher-order “supernodes” predicted to yield scalable gains in thermopower and efficiency. A central question, however, is whether such features are intrinsically more fragile to dephasing. Using $ Büttiker$ voltage-temperature probes, we establish an order-selection rule: the effective near-node order is set by the lowest among coherent and probe-assisted channels. Supernodes are therefore fragile in an absolute sense because their transmission is parametrically suppressed with order. However, once an incoherent floor dominates, the fractional suppression of thermopower, efficiency, and figure of merit becomes universal and order-independent. Illustrating these principles with benzene- and biphenyl-based junction calculations, we show that the geometry of environmental coupling – through a single orbital or across many – dictates whether coherence is lost by order reduction or by floor building. These results yield general scaling rules for the thermoelectric response of interference nodes under dephasing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)
19 pages, 6 figures
Lattice-induced spin dynamics in Dirac magnet CoTiO3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Andrey Baydin, Jiaming Luo, Zhiren He, Jacques Doumani, Tong Lin, Fuyang Tay, Jiaming He, Jianshi Zhou, Guru Khalsa, Junichiro Kono, Hanyu Zhu
Spin-lattice coupling is crucial for understanding the spin transport and dynamics for spintronics and magnonics applications. Recently, cobalt titanate (CoTiO3), an easy-plane antiferromagnet, has been found to host axial phonons with a large magnetic moment, which may originate from spin-lattice coupling. Here, we investigate the effect of light-driven lattice dynamics on the magnetic properties of CoTiO3 using time-resolved spectroscopy with a THz pump and a magneto-optic probe. We found resonantly driven Raman active phonons, phonon-polariton-induced excitation of the antiferromagnetic magnons, and a slow increase in the polarization rotation of the probe, all indicating symmetry breaking that is not intrinsic to the magnetic space group. The temperature dependence confirmed that the observed spin dynamics is related to the magnetic order, and we suggest surface effects as a possible mechanism. Our results of THz-induced spin-lattice dynamics signify that extrinsic symmetry breaking may contribute strongly and unexpectedly to light-driven phenomena in bulk complex oxides.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Optics (physics.optics)
Lee-Yang-zero ratio method in three-dimensional Ising model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Tatsuya Wada, Masakiyo Kitazawa, Kazuyuki Kanaya
By performing Monte Carlo simulations of the three-dimensional Ising model, we apply the recently proposed Lee-Yang-zero ratio (LYZR) method to determine the location of the critical point in this model. We demonstrate that the LYZR method is as powerful as the conventional Binder-cumulant method in studying the critical point, while the LYZR method has the advantage of suppressing the violation of the finite-size scaling and non-linearity near the critical point. We also achieve a precise determination of the values of the LYZRs at the critical point, which are universal numbers. In addition, we propose an alternative method that uses only a single Lee-Yang zero and show that it is also useful for the search for the critical point.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Lattice (hep-lat), High Energy Physics - Phenomenology (hep-ph), Computational Physics (physics.comp-ph)
27 pages, 7 figures
Bosonization in $R$-paraparticle Luttinger models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Dennis F. Salinel, Kristian Hauser A. Villegas
We reintroduce the parafermion-paraboson classification in $ R$ -paraparticles in terms of their average occupation numbers, analogous to Green’s parastatistics. The notion of $ p$ -order in $ R$ -parafermions is also redefined as the maximum number of particles that can occupy a quantum state. An example of an order-$ 2$ $ R$ -parafermion with $ m=2$ internal degrees of freedom is presented, which obeys an exclusion principle that is not Pauli’s. The interacting $ R$ -parafermions are studied in the context of bosonization. Specifically, we show that while density waves are generally bosonic in nature and that flavor-charge separation naturally occurs for any one-dimensional $ R$ -parafermion system described by the Luttinger model, flavor waves do not always satisfy bose statistics. Comparison of the partition functions further show that only $ (p=1)$ -ordered $ R$ -parafermions are compatible with the bosonization procedure in the low-energy limit. Based from these results, we discuss a potential realization of parafermion signatures in one-dimensional systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
16 pages, Submission to SciPost
Toughening beta-Ga2O3 via mechanically seeded dislocations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Zanlin Cheng, Jiawen Zhang, Peng Gao, Guosong Zeng, Xufei Fang, Wenjun Lu
\b{eta}-Ga2O3 is a promising candidate for next-generation semiconductors, but is limited by its intrinsic brittleness, which hinders its application in flexible electronics and high-precision devices. This study explores a new approach to improving the damage tolerance of (001)-oriented \b{eta}-Ga2O3 by introducing mechanically seeded dislocations via surface scratching. By applying a Brinell indenter to scratch the surface along the [100] direction, we effectively generate edge-type dislocations belonging to the (011)[01-1] and/or (0-11)[011] slip systems within a mesoscale wear track. Through a combination of nanoindentation tests, surface morphology analysis, and microstructural characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we reveal that the introduction of dislocations significantly mitigates the formation of cleavage cracks during indentation, in contrast to that observed in as-received \b{eta}-Ga2O3. The mechanically seeded dislocations in the subsurface layers play an important role in preventing brittle fracture by facilitating stable plastic deformation.
Materials Science (cond-mat.mtrl-sci)
Enhanced premelting at the ice-rubber interface using all-atom molecular dynamics simulation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-29 20:00 EDT
Takumi Kojima, Ikki Yasuda, Takumi Sato, Noriyoshi Arai, Kenji Yasuoka
The ice-rubber interface is critical in applications such as tires and shoe outsoles, yet its molecular tribology remains unclear. Using all-atom molecular dynamics simulations, we studied premelting layers at the basal face of ice in contact with styrene-butadiene rubber from 254 to 269 K. Despite its hydrophobicity, rubber enhances structural disorder of interfacial water, promoting premelting. In contrast, water mobility is suppressed by confinement from polymer chains, leading to glassy dynamics distinct from the ice-vapor interface. Near the melting point, rubber chains become more flexible and penetrate the premelting layer, forming a mixed rubber-water region that couples the dynamics of both components. These results suggest that nanoscale roughness and morphology of hydrophobic polymers disrupt ice hydrogen-bond networks, thereby enhancing premelting. Our findings provide molecular-level insight into ice slipperiness and inform the design of polymer materials with controlled ice adhesion and friction.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
Magnetic Field Induced Band Deformation in a Lieb Lattice:Aharonov-Bohm Caging and Zeeman Splitting
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Flat-band systems are highly sensitive to external perturbations, providing a route to study unconventional localization, transport, and spin physics. Lieb lattice, a two-dimensional geometry with an inherent flat band, exemplifies this behavior and is experimentally realizable in ultracold atoms, photonic arrays, and superconducting circuits. In this work, we present a comprehensive study of magnetic field induced band deformation in the Lieb lattice by jointly considering orbital Peierls phases and Zeeman spin splitting. A perpendicular magnetic flux generates Aharonov Bohm caging, confining particles into localized flat-band states, while Zeeman coupling lifts spin degeneracy and induces spin-resolved energy shifts. The competition between these two mechanisms gives rise to rich band restructuring and tunable spin-selective flat-band phenomena. These results establish the Lieb lattice as a controllable setting for spin-selective transport and magneticfield engineering in synthetic quantum platforms such as ultracold atoms, photonic lattices, and superconducting circuits, offering guiding principles for quantum simulation and the corresponding experiments, which opens the avenue for controlled engineering of spin-resolved localization and flat-band physics in synthetic quantum matter.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el)
11 pages;6 figures
Run-and-tumble particle with diffusion: boundary local times and the zero-diffusion limit
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Incorporating boundary conditions into stochastic models of passive or active particle motion is usually implemented at the level of the associated forward or backward Kolmogorov equation, whose solution determines the probability distribution of sample paths. In order to write down the corresponding stochastic differential equation (SDE) that generates the individual sample paths, it is necessary to introduce a Brownian functional that keeps track of the boundary-particle contact time. We previously constructed the SDE for a (non-diffusing) run-and-tumble particle (RTP) on the half-line with either a reflecting or sticky wall at $ x=0$ . In this paper we extend the theory to include the effects of diffusion. One of the non-trivial consequences of combining drift-diffusion with tumbling is that the zero diffusion limit $ D\rightarrow 0$ is singular in the sense that the number of boundary conditions is doubled when $ D>0$ . We use stochastic calculus to derive the forward Kolmogorov equation for two distinct boundary conditions that reduce, respectively, to non-sticky and sticky boundary conditions in the zero-diffusion limit. In the latter case, it is necessary to include a boundary layer in a neighbourhood of the wall and use singular perturbation theory. We also treat the wall as partially absorbing by assuming that the particle is absorbed when the amount of boundary-particle contact time (discrete or continuous local time) exceeds a quenched random threshold. Finally, we analyse the survival probability and corresponding FPT density for absorption at a non-sticky wall by deriving the corresponding backward Kolmogorov equation
Statistical Mechanics (cond-mat.stat-mech)
23 pages, 3 figures
Boson peak in covalent network glasses: Isostaticity and marginal stability
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-29 20:00 EDT
Hideyuki Mizuno, Tatsuya Mori, Giacomo Baldi, Emi Minamitani
The boson peak (BP) stands as a key feature in understanding glasses and amorphous materials. It directly underlies their anomalous material properties, including thermal behaviors such as excess specific heat and low thermal conductivity, as well as mechanical characteristics such as nonaffine elasticity and fragile plasticity. Despite its importance, understanding of the BP remains limited in covalent network glasses. The most promising concepts are isostaticity and marginal stability, which have been established in theories of rigidity percolation and the jamming transition. While these concepts, supported by comprehensive data, account for the BP in packing-based glasses, comparable explanations have not yet been demonstrated for covalent network glasses. Here we study silica glass, a prototypical covalent network glass, using molecular dynamics simulations. We show that the BP in silica glass is governed by near-isostatic constraints and marginal stability, supporting their universality across diverse glassy systems. Furthermore, we reveal that these principles manifest as a wavenumber-independent band in the dynamical structure factor, and we demonstrate consistency with inelastic X-ray scattering data on silica glass. Our results provide a unified, experimentally testable framework for deciphering the BP and for refining the interpretation of scattering data in amorphous materials.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)
21 pages, 11 figures, 4 tables
Bose-Einstein condensate of ultracold sodium-rubidium molecules with tunable dipolar interactions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Zhaopeng Shi, Zerong Huang, Fulin Deng, Wei-Jian Jin, Su Yi, Tao Shi, Dajun Wang
Realizing Bose-Einstein condensation of polar molecules is a long-standing challenge in ultracold physics and quantum science due to near-universal two-body collisional losses. Here, we report the production of a Bose-Einstein condensate of ground-state sodium-rubidium molecules via high efficiency evaporative cooling, with losses suppressed using the dual microwave shielding technique. The ability to tune the dipolar interaction between these ultracold polar molecules is crucial for producing the condensate and enables exciting prospects for future applications. We explore different regimes of dipolar interactions, realizing both the gas phase and the quantum droplet phase of the molecular condensate. This work opens new avenues for investigating quantum matter with strong dipolar interactions and for quantum simulation of long-range many-body systems.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
13 pages, 8 fugures
Extensive entanglement between coupled Tomonaga-Luttinger liquids in and out of equilibrium
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Taufiq Murtadho, Marek Gluza, Nelly H. Y. Ng
Quantum entanglement exists in nature but is absent in classical physics, hence it fundamentally distinguishes quantum from classical theories. While entanglement is routinely observed for few-body systems, it is significantly more challenging to witness in quantum many-body systems. Here, we theoretically study entanglement between two parallel and spatially separated Tomonaga-Luttinger liquids (TLLs) partitioned along the longitudinal axis. In particular, we focus on 1D Bose gases as a realization of TLLs and investigate two experimentally relevant situations: tunnel-coupled gases at finite temperatures and after coherent splitting. In both scenarios, we analytically calculate the logarithmic negativity and identify a threshold temperature below which the system is entangled. Notably, this threshold temperature is accessible in near-term coherent splitting experiments. Furthermore, we investigate the crossover between quantum and classical correlations in the vicinity of the threshold temperature by comparing logarithmic negativity with mutual information. We argue that the initial mutual information established by the coherent splitting is conserved in TLL dynamics, thus preventing certain generalized Gibbs ensembles from being reached during prethermalization. Moreover, both logarithmic negativity and mutual information are found to scale extensively with the subsystem’s length. Although the ground-state entanglement between coupled TLLs has been predicted to be extensive, this setting is largely overlooked compared to other partitions. Our work extends the study of entanglement between coupled TLLs to finite temperatures and out-of-equilibrium regimes, and provides a strategy towards experimental detection of extensive entanglement in quantum many-body systems at finite temperatures.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
34 pages: 23 pages main text + 8 pages references + 3 pages appendices
Physics-informed Hamiltonian learning for large-scale optoelectronic property prediction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Martin Schwade, Shaoming Zhang, Frederik Vonhoff, Frederico P. Delgado, David A. Egger
Predicting optoelectronic properties of large-scale atomistic systems under realistic conditions is crucial for rational materials design, yet computationally prohibitive with first-principles simulations. Recent neural network models have shown promise in overcoming these challenges, but typically require large datasets and lack physical interpretability. Physics-inspired approximate models offer greater data efficiency and intuitive understanding, but often sacrifice accuracy and transferability. Here we present HAMSTER, a physics-informed machine learning framework for predicting the quantum-mechanical Hamiltonian of complex chemical systems. Starting from an approximate model encoding essential physical effects, HAMSTER captures the critical influence of dynamic environments on Hamiltonians using only few explicit first-principles calculations. We demonstrate our approach on halide perovskites, achieving accurate prediction of optoelectronic properties across temperature and compositional variations, and scalability to systems containing tens of thousands of atoms. This work highlights the power of physics-informed Hamiltonian learning for accurate and interpretable optoelectronic property prediction in large, complex systems.
Materials Science (cond-mat.mtrl-sci)
Accurate Screening of Functional Materials with Machine-Learning Potential and Transfer-Learned Regressions: Heusler Alloy Benchmark
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
A machine learning-accelerated high-throughput (HTP) workflow for the discovery of magnetic materials is presented. As a test case, we screened quaternary and all-$ d$ Heusler compounds for stable compounds with large magnetocrystalline anisotropy energy ($ E_{\mathrm{aniso}}$ ). Structure optimization and evaluation of formation energy and distance to hull convex were performed using the eSEN-30M-OAM interatomic potential, while local magnetic moments, phonon stability, magnetic stability, and $ E_{\mathrm{aniso}}$ were predicted by eSEM models trained on our DxMag Heusler database. A frozen transfer learning strategy was employed to improve accuracy. Candidate compounds identified by the ML-HTP workflow were validated with density functional theory, confirming high predictive precision. We also benchmark the performance of different MLIPs, and discuss the fidelity of local magnetic moment prediction and its extension to other magnetic materials.
Materials Science (cond-mat.mtrl-sci)
A perspective on inelastic light scattering spectroscopy for probing transport of collective acoustic excitations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Hyemin Kim, Hyungseok Kim, Taeyong Kim
Understanding and manipulating nanoscale energy transport and conversion processes are essential for diverse applications, ranging from thermoelectrics and energy harvesting to thermal management of microelectronics. While it has long been recognized that acoustic and thermal properties in condensed matters are primarily due to microscopic transport of phonons as quasiparticles, probing thermal acoustic excitations particularly at sub-THz remains a challenge primarily due to limitations in experimental techniques with spatiotemporal resolutions pertinent to probing them. Brillouin light scattering (BLS) and its variant, impulsive stimulated Brillouin scattering (ISS), provide access to these thermal acoustic excitations, enabling measurement of quantities such as acoustic dispersions along with relaxation dynamics occurring in ultrasonic as well as hypersonic frequencies. In this perspective, we provide a brief overview of the operational principles of BLS and ISS, and highlight their applications in probing acoustic, thermal, and magnetic excitations in emerging and low-dimensional materials. We conclude by discussing current challenges and future opportunities for advanced material characterization using Brillouin light scattering spectroscopy techniques.
Materials Science (cond-mat.mtrl-sci)
Decoding local framework dynamics in the ultra-small pore MOF MIL-120(Al) CO2 sorbent with Machine Learned Potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Dong Fan, Felipe Lopes Oliveira, Mohammad Wahiduzzaman, Guillaume Maurin
Metal-organic frameworks (MOFs) with ultra-small pores offer an optimal environment to effectively capture guest molecules such as CO2. Subtle local dynamics of their frameworks, either throughout reorientation of functional groups grafted to the organic linkers or those present in their inorganic nodes, is expected to play a major role in their sorption behaviors. Here, we combine density-functional theory (DFT) with a purpose-trained machine-learned potential to systematically investigate the local dynamics of the bridging hydroxyl groups, {\mu}2-OH groups present in the prototypical ultra-small pore MOF MIL-120(Al), reported recently as an attractive CO2 sorbent. We identified six MOF configurations associated with distinct {\mu}2-OH orientations with relatively low interconversion energy barriers (0.07-0.19 eV per unit cell) suggesting that all these states can be observed experimentally at room temperature. We demonstrated that our MLP achieves near-DFT-level fidelity, reproducing the energy barriers and phonon spectra of the empty MOF, and accurately predicting CO2 adsorption geometries depending on the {\mu}2-OH orientations with CO2 adopting either parallel or perpendicular alignment to the pore axis, which in turn governs the adsorption energetics. This work establishes that a reliable description of the local structure, such as reorientation/flipping of bridging hydroxyl groups, is a key feature to gain an accurate description of the guest locations and energetics in ultra-small pore MOFs.
Materials Science (cond-mat.mtrl-sci)
19 pages, 4 figures
The total energy approach for calculating the specific heat of liquids and glasses
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-29 20:00 EDT
The recent development of the calculation of specific heat ($ C$ ) of liquids and glasses by first-principles molecular dynamics (MD) simulations is reviewed. Liquid and glass states have common properties in that there is no periodicity and the atom relaxation has an important role in their thermodynamic properties. These properties have, for a long time, hindered the construction of an appropriate theory of $ C$ for these states. The total energy approach based on the density-functional theory (DFT) provides a universal method to calculate $ C$ , irrespective of the material states. However, aside from the convergence problem, even DFT-based MD simulations give different values for a thermodynamic property of liquids and glasses, depending on the setup of MD simulations. The essential problem is atom relaxation, which affects the relationship between the energy and temperature $ T$ . The temperature is determined by the equilibrium state, but there are many metastable states for glasses. Metastable states are stable within their relaxation times. We encounter the difficult problem of hysteresis, which is the most profound consequence of irreversibility. Irreversibility occurs even for quasistatic processes. This is the most difficult and confusing point in the thermodynamics literature. Here, a consistent treatment of both equilibrium properties and irreversibility in adiabatic MD simulations, which has no frictional term, is given by taking multi-timescales into account. A leading principle to determine the equilibrium is provided by the second law of thermodynamics. The basic ideas and the usefulness of the total energy approach in real calculations are presented.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Emergent dynamics of active elastic microbeams
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-29 20:00 EDT
Q. Martinet, Y. Li, A. Aubret, E. Hannezo, J. Palacci
In equilibrium, the physical properties of matter are set by the interactions between the constituents. In contrast, the energy input of the individual components controls the behavior of synthetic or living active matter. Great progress has been made in understanding the emergent phenomena in active fluids, though their inability to resist shear forces hinders their practical use. This motivates the exploration of active solids as shape-shifting materials, yet, we lack controlled synthetic systems to devise active solids with unconventional properties. %and bridge the gap between active solids made of macroscopic robots and the complexity of biological materials. Here we build active elastic beams from dozens of active colloids and unveil complex emergent behaviors such as self-oscillations or persistent rotations. Developing tensile tests at the microscale, we show that the active beams are ultra-soft materials, with large (non-equilibrium) fluctuations. Combining experiments, theory, and stochastic inference, we show that the dynamics of the active beams can be mapped on different phase transitions which are tuned by boundary conditions. More quantitatively, we assess all relevant parameters by independent measurements or first-principles calculations, and find that our theoretical description agrees with the experimental observations. Our results demonstrate that the simple addition of activity to an elastic beam unveils novel physics and can inspire design strategies for active solids and functional microscopic machines.
Soft Condensed Matter (cond-mat.soft)
Prediction of EDS Maps from 4DSTEM Diffraction Patterns Using Convolutional Neural Networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Understanding the relationship between atomic structure (order) and chemical composition (chemistry) is critical for advancing materials science, yet traditional spectroscopic techniques can be slow and damaging to sensitive samples. Four-dimensional scanning transmission electron microscopy (4D-STEM) captures detailed diffraction patterns across scanned regions, providing rich structural information, while energy dispersive X-ray spectroscopy (EDS) offers complementary chemical data. In this work, we develop a machine learning framework that predicts EDS spectra directly from 4D-STEM diffraction patterns, reducing beam exposure and acquisition time. A convolutional neural network (CNN) accurately infers elemental compositions, particularly for elements with strong diffraction contrast or higher concentrations, such as Oxygen and Tellurium. Both extrapolation and interpolation strategies demonstrate consistent performance, with improved predictions when additional structural context is available. Visual and cross-correlation analyses confirm the model’s ability to capture global and local compositional trends. This approach establishes a data-driven pathway to non-destructive, high-throughput materials characterization.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Evanescent random walker on networks: Hitting times, budget renewal, and survival dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Thomas M. Michelitsch, Alejandro P. Riascos
We consider a mortal random walker evolving with discrete time on a network, where transitions follow a degree-biased Markovian navigation strategy. The walker starts with a random initial budget $ T_1 \in \mathbb{N}$ and must maintain a strictly positive budget to remain alive. Each step incurs a unit cost, decrementing the budget by one; the walker perishes (is ruined) upon depletion of the budget. However, when the walker reaches designated target nodes, the budget is renewed by an independent and identically distributed (IID) copy of its initial value. The degree bias is tuned to either favor or disfavor visits to these target nodes. Our model exhibits connections with stochastic resetting. The evolution of the budget can be interpreted as a deterministic drift on the integer line toward negative values, where the walker is intermittently reset to positive IID random positions and dies at the first hit of the origin. The first part of the paper focuses on the target-hitting statistics of an immortal Markovian walker. We analyze the \textit{target hitting counting process} (THCP) for an arbitrary set of target nodes. Within this framework, the second part of the paper addresses the dynamics of the evanescent walker. We derive analytical results for arbitrary configurations of target nodes, including the evanescent propagator matrix, the survival probability, the mean residence time on a set of nodes during the walker’s lifetime, and the expected lifetime itself. Additionally, we compute the expected number of target hits (i.e., budget renewals) in a lifetime of the walker and related distributions. We explore both analytically and numerically various scenarios affecting the life expectancy of the walker.
Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)
38 pages, 9 figures
Electric-field induced half-metallicity in a two-dimensional ferromagnetic Janus VSSe bilayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Khushboo Dange, Shivprasad S. Shastri, Alok Shukla
Two-dimensional (2D) half-metals with intrinsic ferromagnetism hold great potential for applications in spintronics. In this study, we aim to expand the known space of such 2D ferromagnetic (FM) half-metals by investigating bilayer of Janus VSSe, an FM semiconductor. Its structural, electronic, and magnetic properties are examined using density functional theory, employing the DFT+$ U$ method, coupled with the PBE functional. The stability of the bilayer is examined using ab initio molecular dynamics simulations at finite temperatures up to 400 K. To ensure the stability further, the elastic constants of the system have also been investigated and we found that VSSe bilayer manifests an easy plane of magnetization similar to its monolayer counterpart. At the DFT+$ U$ level, the considered VSSe bilayer exhibits a tendency towards half-metallicity with a small band gap of 0.11 eV for the majority spin carriers, and of 0.66 eV for the minority ones. To include a transition from a semiconductor to a half-metal, the bilayer is subjected to an external electric field of varying strengths normal to the plane. The lack of horizontal mirror symmetry in the bilayer allows bidirectional tuning of the band gap, with different values for the field in “upward” and “downward” directions. The band gaps for the two spin channels increase with the increasing upward electric field, while the opposite happens for the downward fields, with the majority carrier gap closing at 0.16 V/$ \unicode{x212B}$ , making the material a spin gapless semiconductor. Further increase in the electric field renders the material half metallic at 0.18 V/$ \unicode{x212B}$ . Given the fact that these values of the external electric field are achievable in the lab suggests that the FM Janus VSSe bilayer is a promising candidate for spintronic devices.
Materials Science (cond-mat.mtrl-sci)
41 pages, 13 figures in the Manuscript and 8 figures in the Supplemental Material
Physical Review B 112, 075307 (2025)
Dynamic compression of glassy GeO$2$ up to the TPa range and first observation of shock induced crystallization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
R. Torchio, J.A. Hernandez, A. Cordone, S.Balugani, T. Vinci, A. Ravasio, C. Pepin, N. Sevelin-Radiguet, E. Guillam, F. Dorchies, A.Benuzzi
In this work we present an extensive study of glassy GeO$ _2$ under laser induced dynamic compression. New VISAR and SOP data provide the extension of Hugoniot EoS up to the TPa range for this material including temperature measurements. Reflectivity data at both 532 and 1064 nm wavelenght are also reported. In the low compression range we observe changes of the optical properties from transparent, to opaque, to metallic state. The second part of this work describes a further laser shock experiment combined with in-situ X-ray diffraction. Here we observe, for the first time, the laser shock-induced crystallization of glassy GeO$ _2$ to a structure compatible with the rutile phase at pressure higher than 20 GPa and melting occurring at around 75 GPa.
Materials Science (cond-mat.mtrl-sci)
9 pages, 15 figures
Stability of many-body localization in two dimensions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Junhyeok Hur, Joey Li, Byungjin Lee, Kiryang Kwon, Minseok Kim, Samgyu Hwang, Sumin Kim, Yong Soo Yu, Amos Chan, Thorsten Wahl, Jae-yoon Choi
Disordered quantum many-body systems pose one of the central challenges in condensed matter physics and quantum information science, as their dynamics are generally intractable for classical computation. Many-body localization (MBL), hypothesized to evade thermalization indefinitely under strong disorder, exemplifies this difficulty. Here, we study the stability of MBL in two dimensions using ultracold atoms in optical lattices with variable system sizes up to $ 24\times 24$ sites, well beyond the classically simulable regime. Using the imbalance as a probe, we trace the long-time dynamics under two distinctive disorder potentials: quasiperiodic and random disorder. For random disorder, the MBL crossover point shifts to higher disorder strength with increasing system size, consistent with the avalanche scenario. In contrast, with quasiperiodic disorder, we observe no clear system size dependence, suggesting possible stability of MBL in two dimensions.
Quantum Gases (cond-mat.quant-gas), Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
17 pages, 12 figures
Magnetism and nonlinear charge transport in NiFe2O4/γ-Al2O3/SrTiO3 heterostructure for spintronic applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Amit Chanda, Thor Hvid-Olsen, Christina Hoegfeldt, Anshu Gupta, Alessandro Palliotto, Maja A. Dunstan, Kasper S. Pedersen, Dae-Sung Park, Damon J. Carrad, Thomas Sand Jespersen, Felix Trier
We present the synthesis and study of the magnetic and electronic properties of NiFe2O4/{\gamma}-Al2O3/SrTiO3 heterostructure. The {\gamma}-Al2O3/SrTiO3 interface hosts a high-mobility two-dimensional electron gas (2DEG) with large spin-orbit coupling, making it promising for spintronics applications if it can be coupled to a suitable source of spin currents. Here, we synthesize a ferrimagnetic insulating NiFe2O4(001) layer on {\gamma}-Al2O3(001)/SrTiO3(001) using a low-temperature reactive sputtering at 150 deg C without compromising the mobility and charge carrier density of the 2DEG at the {\gamma}-Al2O3(001)/SrTiO3(001) interface. The sheet resistance of both {\gamma}-Al2O3/SrTiO3 and NiFe2O4/{\gamma}-Al2O3/SrTiO3 exhibits metallic behavior down to cryogenic temperatures, with a low temperature upturn driven by the Kondo-like scattering. Most importantly, NiFe2O4/{\gamma}-Al2O3/SrTiO3 behaves as a magnetic diode at low temperatures, and its rectification performance increases significantly with increasing magnetic field strength giving rise to a robust magneto-electronic rectification effect at low temperatures, which provides a first step towards the development of all-oxide heterostructures capable of efficient spin-charge conversion.
Materials Science (cond-mat.mtrl-sci)
28 pages, 5 figures
Integrability from a Single Conservation Law in Quantum Spin Chains
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
We prove that for quantum spin chains with finite-range interactions, the existence of a specific conservation law known as the Reshetikhin condition implies the presence of infinitely many local conserved quantities, i.e., integrability. This shows that the entire hierarchy of conservation laws associated with solutions of the Yang–Baxter equation is already encoded in the lowest nontrivial conservation law. Combined with recent rigorous results on nonintegrability, our theorem strongly restricts the possibility of partially integrable systems that admit only a finite but large number of local conserved quantities. Our work establishes a rigorous foundation for the systematic identification of new integrable models and deepens the algebraic understanding of conservation-law structures in quantum spin chains.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Exactly Solvable and Integrable Systems (nlin.SI), Quantum Physics (quant-ph)
7 pages (Supplemental Material: 10 pages)
Ultrafast solid-state chemical synthesis of BaTiO3 initiated by gyrotron microwave radiation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
S.V. Sintsov, N.V. Chekmarev, K.I. Rybakov, A.A. Sorokin, E.I. Preobrazhenskii, A.V. Vodopyanov
This work presents the results of a study on the solid-state synthesis of barium titanate under continuous microwave radiation from a 24 GHz gyrotron in a multimode cavity reactor. It is shown that in localized domains where fine-scale thermal instabilities develop, initiated by microwave radiation within the initial stoichiometric reaction mixture of ultrafine barium carbonate and titanium dioxide powders, the synthesis can proceed within 1,5 - 7 minutes, achieving a target product yield of up to 90%. Based on a developed realistic numerical model of the multimode reactor, involving an iterative solution of stationary Maxwell and heat conduction equations, it is demonstrated that the specific absorbed power in the domains where fine-scale thermal instabilities develop can reach 670 W/cm3 under an input microwave power of 400 W.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Plasma Physics (physics.plasm-ph)
A Replica Stoner Theory for Dirty Ferromagnets
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-29 20:00 EDT
This paper investigates the effect of disorder on a ferromagnetic metal with repulsive interactions. We assume that, in the clean limit, the ferromagnetic state can be described by Stoner mean-field theory and study how disorder affects the the system by using a combined replica + Stoner mean-field approach. At zero temperature, we find that a replica-symmetric ferromagnetic mean-field solution exists in the presence of disorder with a modified Stoner criteria where the ferromagnetism is enhanced by disorder. At finite temperature, a Landau theory is employed to construct the phase diagram, revealing that beyond a critical disorder strength, a spin-glass phase may exist between the high-temperature paramagnetic phase and the low-temperature ferromagnetic phase. For weak (repulsive) interaction where the system is non-ferromagnetic in the clean limit, the possibility of a disordered-induced ferromagnetic ground state is observed both at zero temperature and finite temperature. The potential applicability of this framework to realistic materials is briefly discussed.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
14 pages, 3 figures, submitted to Physical Review B
A two-state generalisation of the strong collision model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Muon spin relaxation is a powerful technique for probing static and dynamic local magnetic fields. The strong collision model, based on a Gaussian-Markovian process, is commonly used to account for dynamical effects. Yet, it remains limited in describing systems where the local field undergoes discrete state changes. To address this, I introduce a generalized two-state strong collision model that explicitly incorporates transitions between distinct local field environments during fluctuations. This extension allows for a more accurate representation of dynamical effects, particularly in systems where each collision alters the underlying static polarisation function. Analytical and numerical solutions are presented, and the model’s applicability is demonstrated {\color{black}and discussed} across relevant physical systems – including low-dimensional magnets, systems with dynamic disorder and ion and muon diffusion. These results offer an enhanced framework for interpreting data in complex materials and extend the method’s reach to a broader class of dynamical phenomena in condensed matter physics.
Strongly Correlated Electrons (cond-mat.str-el)
Phys. Rev. B 112, 024309 (2025)
Revival of Layered Ferroelectrics in Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Layered perovskites are a versatile class of ferroelectrics with their structural anisotropy reflected in unusual electrostatics that give rise to exceptional ferroelectric properties. These materials fall into four main families: Aurivillius, Carpy-Galy, Ruddlesden-Popper, and Dion-Jacobson phases; each forming natural superlattices by interleaving perovskite slabs with spacer layers. For a long time, these materials were considered too structurally complex to prepare as high-quality thin films. However, recent breakthroughs in deposition and advanced characterization have made it possible to stabilize high-quality films with atomic precision, uncovering a wide range of unconventional ferroelectric functionalities. These include robust in-plane polarization without a critical thickness, the emergence of charged domain walls and non-trivial polar textures, resilience to doping with magnetic ions and charge carriers, and possibility to epitaxially integrate them into standard perovskite heterostructures. This review aims to unify current knowledge on the fabrication and characterization of layered ferroelectric thin films, and to present research findings across all four structural families, with the goal of highlighting their common features despite differences in crystal structure and polarization mechanisms. We also discuss promising research directions, including polar metallicity, (alter-)magnetoelectricity, exfoliation, and soft-chemistry-driven phase transformations, with the goal of consolidating the field and encouraging further exploration of these materials for both fundamental studies and applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
Literature review, 37 pages, 14 figures
Anomalous diffusion and run-and-tumble motion of a chemotactic particle in low dimensions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Jacopo Romano, Andrea Gambassi
We study the stochastic dynamics of a symmetric self-chemotactic particle and determine the long-time behavior of its mean squared displacement (MSD). The attractive or repulsive interaction of the particle with the chemical field that it generates induces a non-linear, non-Markovian effective dynamics, which results into anomalous diffusion for spatial dimensions $ d \leq 2$ . In one spatial dimension, we map the case of repulsive chemotaxis onto a run-and-tumble-like dynamics, leading to an MSD which, as a function of the elapsed time $ t$ , grows superdiffusively with exponent $ 4/3$ . In the presence of attractive chemotaxis, instead, the particle exhibits a slowdown, with the MSD growing logarithmically with time. In $ d=2$ , we find logarithmic aging of the diffusion coefficient, while in $ d=3$ the motion reverts standard diffusive behavior with a renormalized diffusion coefficient.
Statistical Mechanics (cond-mat.stat-mech)
Topological invariant responsible for the stability of the Fermi surfaces in non - homogeneous systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
The topological invariant responsible for the stability of Fermi point/Fermi surface in homogeneous systems is expressed through the one particle Green function, which depends on momentum. It is given by an integral over the 3D hypersurface in momentum space surrounding the Fermi surface. Notion of Fermi surface may be extended to the non - homogeneous systems using Wigner - Weyl calculus. The Fermi surface becomes coordinate dependent, it may be defined as the position of the singularity in momentum space of the Wigner transformed Green function. Then the topological invariant responsible for the stability of this Fermi surface is given by the same expression as for the homogeneous case, in which the Green function is replaced by its Wigner transformation while the ordinary products are replaced by the Moyal products. We illustrate the proposed construction by the examples of the systems, in which the given topological invariant is nontrivial and may be calculated explicitly.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Latex, 10 pages; Supplementary Materials, 6 pages
A configuration interaction approach to solve the Anderson impurity model; applications to elemental Ce
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
Basile Herzog, Patrik Thunström, Olle Eriksson
Accurate calculations of strongly correlated materials remain a formidable challenge in condensed matter physics, particularly due to the computational demand of conventional methods. This paper presents an efficient solver for dynamical mean field theory using configuration interaction (CI). The method is shown to have improved efficiency compared to traditional, exact diagonalization approaches. Hence, it provides an accessible, open-source alternative that can be executed on standard laptop computers or on supercomputers. The solver is demonstrated on cerium in the $ \gamma$ -, $ \alpha$ - and $ \epsilon$ -phases. An analysis of how the electronic structure of Ce evolves as function of lattice compression is made. It is argued that the electronic structure evolves from a localized nature of the 4f shell in $ \gamma$ -Ce to an essentially itinerant nature of the 4f shell of $ \epsilon$ -Ce. The transition between these two phases, as function of compression, can hence be seen as a Mott transition. However, this transition is intercepted by the strongly correlated $ \alpha$ -phase of elemental Ce, for which the 4f shell forms a Kondo singlet.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 10 figures
Distinct Spatiotemporal Dynamics of Thermoelectric Transport Across Superconducting Transition
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-29 20:00 EDT
Rajae Malek, Qing-Dong Jiang, Haiwen Liu
We investigate the relaxation dynamics of heat transport in superconductors, shaped by the interplay of diffusion, nonlinearity, and magnetic fields. Focusing on regimes near the critical temperature Tc, we analyze two classes of relaxation diffusion equations that give rise to qualitatively distinct dynamics, which we denote as Type I (linear) and Type II (nonlinear). Type I relaxation, characteristic of the normal state above Tc, results in a steady and spatially uniform heat current governed by linear diffusion. By contrast, Type II relaxation, relevant below Tc, exhibits non steady dynamics marked by pronounced spatial inhomogeneities and an evolving pattern, in which an initially localized hot spot propagates transiently through the system. The striking distinction between these regimes underscores a fundamental shift in transport mechanisms across the superconducting phase transition and provides experimentally relevant predictions in light of emerging techniques for probing local dissipation.
Superconductivity (cond-mat.supr-con)
Apparatus for quantum-mixture research in microgravity
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-29 20:00 EDT
Baptist Piest, Jonas Böhm, Timothé Estrampes, Annie Pichery, Paweł Arciszewski, Wolfgang Bartosch, Sören Boles, Klaus Döringshoff, Michael Elsen, Priyanka Guggilam, Ortwin Hellmig, Christian Kürbis, Dorthe Leopoldt, Gabriel Müller, Alexandros Papakonstantinou, Christian Reichelt, André Wenzlawski, Thijs Wendrich, Éric Charron, Achim Peters, Klaus Sengstock, Andreas Wicht, Patrick Windpassinger, Jens Grosse, Naceur Gaaloul, Ernst Maria Rasel
Experiments with ultracold quantum gases are a rapidly advancing research field with many applications in fundamental physics and quantum technology. Here, we report on a high-flux generation of Bose-Einstein condensate mixtures of $ ^{41}$ K and $ ^{87}$ Rb, using a fully integrated sounding rocket setup. We investigate the release and the free expansion of the quantum mixtures for different orientations to gravity. The release dynamics are governed by the mixture interactions as well as the decaying magnetic field during the release. The latter can be minimized by a dedicated switch-off protocol of the trap generating currents where an exact model enabled us to characterize the interaction effects. Our results establish a new benchmark for generating ultracold mixtures on mobile platforms, with direct relevance for future experiments on interacting quantum gases and tests of the equivalence principle in space.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Confinement in the three-state Potts quantum spin chain in extreme ferromagnetic limit
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Anna Krasznai, Sergei Rutkevich, Gábor Takács
We examine the dynamics of the three-state Potts quantum spin chain in the extreme ferromagnetic regime using perturbation theory in the transverse magnetic field. We demonstrate that this approach provides access to features well beyond the semiclassical method applied previously, including the description of resonant excitations and analytic prediction for the time evolution after a quantum quench. We also demonstrate that it agrees with the meson/bubble spectrum results from exact diagonalisation and the numerical simulations of the time evolution.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
44 pages, pdflatex
Multicritical Infection Spreading
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Leone V. Luzzatto, Juan Felipe Barrera López, István A. Kovács
The contact process is a simple infection spreading model showcasing an out-of-equilibrium phase transition between a macroscopically active and an inactive phase. Such absorbing state phase transitions are often sensitive to the presence of quenched disorder. Traditionally, a phase transition in the disordered contact process is either triggered by dilution or by locally varying the infection rate. However, when both factors play an important role, a multicritical point emerges that remains poorly understood. Here, we study the multicritical contact process by large-scale Monte Carlo simulations in two and three dimensions. The multicritical behavior is found to be universal and exhibits ultra-slow, activated dynamical scaling, with exponents consistent with those predicted by the strong disorder renormalization group method. This finding indicates that the multicritical contact process belongs to the same universality class as the multicritical quantum Ising model, opening future directions to measure quantum entanglement properties via classical simulations.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Populations and Evolution (q-bio.PE)
10 pages, 6 figures
Subspace-Protected Topological Phases and Bulk-Boundary Correspondence
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Kenji Shimomura, Ryo Takami, Daichi Nakamura, Masatoshi Sato
While tremendous research has revealed that symmetry enriches topological phases of matter, more general principles that protect topological phases have yet to be explored. In this Letter, we elucidate the roles of subspaces in free-fermionic topological phases. A subspace property for Hamiltonians enables us to define new topological invariants. They result in peculiar topological boundary phenomena, i.e., the emergence of an unpaired zero mode or zero-winding skin modes, characterizing subspace-protected topological phases. We establish and demonstrate the bulk-boundary correspondence in subspace-protected topological phases. We further discuss the interplay of the subspace property and internal symmetries. Toward application, we also propose possible platforms possessing the subspace property.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
9 pages, 3 figures
Electrode modified domain morphology in ferroelectric capacitors revealed by X-ray microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Megan O. Hill Landberg, Bixin Yan, Huaiyu Chen, Efe Ipek, Morgan Trassin, Jesper Wallentin
Ferroelectric thin films present a powerful platform for next generation computing and memory applications. However, domain morphology and dynamics in buried ferroelectric stacks have remained underexplored, despite the importance for real device performance. Here, nanoprobe X-ray diffraction (nano-XRD) is used to image ferroelectric domains inside BiFeO3-based capacitors, revealing striking differences from bare films such as local disorder in domain architecture and partial polarization reorientation. We demonstrate sensitivity to ferroelectric reversal in poled capacitors, revealing expansive/compressive (001) strain for up-/down-polarization using nano-XRD. We observe quantitative and qualitative differences between poling by piezoresponse force microscopy (PFM) and in devices. Further, biasing induces lattice tilt at electrode edges which may modify performance in down-scaled devices. Direct comparison with PFM polarized structures even demonstrates potential nano-XRD sensitivity to domain walls. Our results establish nano-XRD as a noninvasive probe of buried ferroelectric domain morphologies and dynamics, opening avenues for operando characterization of energy-efficient nanoscale devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 11 figures, includes main text and supplementary information
Control of polarization and polar chiral textures in BiFeO$_3$ by epitaxial strain and interfacial chemistry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Elzbieta Gradauskaite, Natascha Gray, Quintin N. Meier, Marta D. Rossell, Morgan Trassin
The balance between interfacial chemistry, electrostatics, and epitaxial strain plays a crucial role in stabilizing polarization in ferroelectric thin films. Here, we bring these contributions into competition in BiFeO$ _3$ (BFO) thin films grown on the charged-surface-terminated La$ _{0.7}$ Sr$ _{0.3}$ MnO$ _3$ (LSMO)-buffered NdGaO$ _3$ (001) substrates. The large anisotropic compressive strain from the substrate promotes the formation of ferroelectric domains despite the expected stabilization of a uniform out-of-plane polarization by the (La,Sr)O$ ^{0.7+}$ termination of the metallic buffer. Piezoresponse force microscopy and scanning transmission electron microscopy reveal that the resulting nanoscale domain architecture is stabilized by the deterministic formation of a fluorite-like Bi$ _2$ O$ _2$ surface layer on regions polarized oppositely to the LSMO-imposed polarization orientation. Leveraging this polarization compensation mechanism, we stabilize a uniform out-of-plane polarization in our highly strained BFO films by inserting a Bi$ _2$ O$ _2$ -terminated Aurivillius film as a buffer layer. Additionally, we reveal signatures of homochiral polarization textures in our BFO films on the level of domain configurations using local polarization switching experiments. Our work thus brings new strategies for controlling polarization direction and chiral textures in oxide ferroelectrics, opening pathways for functional domain-wall and domain-based electronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 4 main-text figures, 3 supplementary figures
Gate-tunable nonreciprocal thermoelectric effects on the surface states of topological insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Phillip Mercebach, Sun-Yong Hwang, Bo Lu, Björn Sothmann, Yukio Tanaka, Pablo Burset
Thermoelectric devices at the nanoscale offer promising routes for on-chip refrigeration and waste-heat recovery, yet most semiconductor-based implementations suffer from limited tunability and narrow operational ranges. We introduce a highly flexible thermoelectric platform based on a ballistic junction formed by two gate-tunable regions of a topological insulator surface state bridged by a magnetic barrier. We theoretically demonstrate that such device exhibits strong electrical control over both refrigeration and thermoelectric power generation via side gates. We exploit the interplay between strong spin-orbit coupling and magnetism to achieve pronounced nonreciprocal transport, asymmetric cooling and tunable diode-like behavior. To demonstrate experimental feasibility, we further analyze refrigeration efficiency and phonon-limited performance in realistic material settings.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 9 figures
Microscopic and collective signatures of feature learning in neural networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-08-29 20:00 EDT
Andrea Corti, Rosalba Pacelli, Pietro Rotondo, Marco Gherardi
Feature extraction - the ability to identify relevant properties of data - is a key factor underlying the success of deep learning. Yet, it has proved difficult to elucidate its nature within existing predictive theories, to the extent that there is no consensus on the very definition of feature learning. A promising hint in this direction comes from previous phenomenological observations of quasi-universal aspects in the training dynamics of neural networks, displayed by simple properties of feature geometry. We address this problem within a statistical-mechanics framework for Bayesian learning in one hidden layer neural networks with standard parameterization. Analytical computations in the proportional limit (when both the network width and the size of the training set are large) can quantify fingerprints of feature learning, both collective ones (related to manifold geometry) and microscopic ones (related to the weights). In particular, (i) the distance between different class manifolds in feature space is a nonmonotonic function of the temperature, which we interpret as the equilibrium counterpart of a phenomenon observed under gradient descent (GD) dynamics, and (ii) the microscopic learnable parameters in the network undergo a finite data-dependent displacement with respect to the infinite-width limit, and develop correlations. These results indicate that nontrivial feature learning is at play in a regime where the posterior predictive distribution is that of Gaussian process regression with a trivially rescaled prior.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Quantum melting a Wigner crystal into Hall liquids
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Recent experiments have shown that, counterintuitively, applying a magnetic field to a Wigner crystal can induce quantum Hall effects. In this work, using variational Monte Carlo, we show that magnetic fields can melt zero-field Wigner crystals into integer quantum Hall liquids. This melting originates from quantum oscillations in the liquid’s ground state energy, which develops downward cusps at integer filling factors due to incompressibility. Our calculations establish a range of densities in which this quantum melting transition occurs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 4 figures
Evolution of quasiparticle edge states with Hubbard interaction in Rice-Mele chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
We study the behaviour of edge states in Rice-Mele model with Hubbard interaction, U , at half-filling using density matrix renormalization group, exact diagonalization and effective charge dynamics in Kumar representation. For a fixed dimerization, $ \delta$ , and staggered potential, V , we find by increasing U the quasiparticle edge states in the charge gap to come down in energy from V in the absence of Hubbard interaction to zero energy for U $ \approx$ 2V . This presents an uncommon case where repulsion leads to zero-energy edge states. Upon increasing U further, the edge state energy starts increasing again until they are lost in the bulk. However, upon increasing U even further, these edge states reappear in the high energy gap. So, with Hubbard interaction, the edge states in Rice-Mele chain transmigrate from the physical charge gap to a high energy gap.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages and 10 figures
Optical Response by Time-Varying Plasmonic Nanoparticles
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-29 20:00 EDT
Miguel Verde, Paloma A. Huidobro
The temporal modulation of material parameters enables optical amplification within linear media. Here we consider the fundamental building block of plasmonics, a subwavelength metal nanoparticle, and study how temporal modulation alters the optical response of the frequency-dispersive scatterers. We show that modulating in time leads to Floquet replicas of the localized surface plasmon resonance of the nanoparticle, which can result in light amplification. We propose a model based on a point-like dipole description of the time-varying frequency-dispersive nanoparticle that fully captures the radiative and amplifying properties of the system in the subwavelength regime. By comparing our simplified model to full Floquet-Mie scattering calculations, we demonstrate that the optical scattering by the nanoparticle is accurately described by an analytical two-band model. This allows us to introduce a two-frequency effective polarizability that fully incorporates the properties of the localized surface plasmon and its amplifying replica, as well as their interaction. In addition, we analyze the emergence of the parametric amplification condition for the modulated nanoparticle, showing that amplification can be obtained in a broad range of parameters.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
Controlled spin-to-charge conversion in noncollinear antiferromagnet-based Py/Mn$_{3}$Pt heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Indraneel Sinha, Saurav Sachin, Prashant Kumar, Atul Pandey, Bijoy Kumar Kuanr, Sujit Manna
Noncollinear antiferromagnets (NCAFs) have recently emerged as promising candidates for future spintronic technologies, offering ultrafast switching, negligible stray fields allowing dense packing, and robustness against external magnetic perturbations. When interfaced with ferromagnets (FMs), they can strongly influence interfacial exchange and spin-torque mechanisms that enable manipulating magnetic order and realizing functionalities beyond conventional heavy metals (HMs) based FM/HM heterostructures. Here, we perform a broadband ferromagnetic resonance (FMR) study to systematically investigate the magnetization dynamics and spin-to-charge conversion in permalloy (Py) and Mn$ 3$ Pt bilayers. High-quality Py films provide a well-defined FMR spectra with a low Gilbert damping parameter ( $ \alpha{\mathrm{eff}} \approx 9.8 \times 10^{-3}$ ). We observe a pronounced enhancement of damping with intrinsic value $ \alpha_{\mathrm{int}} \approx 3.1 \times 10^{-2}$ in the Py/Mn$ 3$ Pt bilayer, indicating efficient spin pumping into the NCAF layer. Frequency dependent linewidth analysis shows a predominantly Gilbert type damping in the bilayers and the corresponding effective spin-mixing conductance ( $ g^{\uparrow\downarrow}{\mathrm{eff}} \approx 4.8 \times 10^{18}$ m$ ^{-2}$ ) is comparable to that of other high-performance antiferromagnetic heterostructures. These results are significant for establishing NCAFs as a candidate material for spin generation and highlights the potential of Py/Mn$ _3$ Pt bilayers for efficient and ultrafast spintronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages with 5 figures
Lithiation Analysis of Metal Components for Li-Ion Battery using Ion Beams
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Arturo Galindo, Neubi Xavier, Noelia Maldonado, Jesús Díaz-Sánchez, Carmen Morant, Gastón García, Celia Polop, Qiong Cai, Enrique Vasco
Metal components are extensively used as current collectors, anodes, and interlayers in lithium-ion batteries. Integrating these functions into one component enhances the cell energy density and simplifies its design. However, this multifunctional component must meet stringent requirements, including high and reversible Li storage capacity, rapid lithiation/delithiation kinetics, mechanical stability, and safety. Six single-atom metals (Mg, Zn, Al, Ag, Sn and Cu) are screened for lithiation behavior through their interaction with ion beams in electrochemically tested samples subjected to both weak and strong lithiation regimes. These different lithiation regimes allowed us to differentiate between the thermodynamics and kinetic aspects of the lithiation process. Three types of ions are used to determine Li depth profile: $ H^+$ for nuclear reaction analysis (NRA), $ He^+$ for Rutherford backscattering (RBS), and $ Ga^+$ for focused ion beam (FIB) milling. The study reveals three lithiation behaviors: (i) Zn, Al, Sn form pure alloys with Li; (ii) Mg, Ag create intercalation solid solutions; (iii) Cu acts as a lithiation barrier. NRA and RBS offer direct and quantitative data, providing a more comprehensive understanding of the lithiation process in LIB components. These findings fit well with our ab-initio simulation results, establishing a direct correlation between electrochemical features and fundamental thermodynamic parameters.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
33 pages, one graphical abstract and 9 figures
Spin structures and phase diagrams of the spin-$\frac{5}{2}$ triangular-lattice antiferromagnet Na$_2$BaMn(PO$_4$)$_2$ under magnetic field
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-29 20:00 EDT
N. Biniskos, F. J. dos Santos, M. Stekiel, K. Schmalzl, E. Ressouche, D. Sviták, A. Labh, M. Vališka, N. Marzari, P. Čermák
We combine single-crystal neutron diffraction studies and Monte Carlo simulations to determine the spin structures and finite-temperature phase diagram of the spin-5/2 triangular-lattice antiferromagnet Na$ _2$ BaMn(PO$ _4$ )$ _2$ in magnetic field. With the application of a magnetic field in two different directions, namely along the $ c$ -axis and in the $ ab$ -plane of the trigonal symmetry, we track the evolution of the spin structure through changes of the magnetic propagation vector. We account for these results with a minimal Heisenberg Hamiltonian that includes easy-axis anisotropy and weak, frustrated interlayer couplings in addition to intralayer exchange. Guided by representation analysis, we refine symmetry-allowed modes to the measured intensities and obtain the spin structures for all field-induced phases, which we compare quantitatively with simulated configurations. Taken together, our measurements and simulations show that frustrated interlayer exchange – rather than purely 2D physics – organizes the unexpectedly rich field-induced phases of Na$ _2$ BaMn(PO$ _4$ )$ _2$ .
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
11 pages, 8 figures
Topotactic phase transition in epitaxial La0.7Sr0.3MnO3-δ films induced by oxygen getter assisted thermal annealing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Chenyang Yin, Lei Cao, Xue Bai, Suqin He, Hengbo Zhang, Tomas Duchon, Felix Gunkel, Yunxia Zhou, Mao Wang, Anton Kaus, Janghyun Jo, Rafal E. Dunin-Borkowski, Shengqiang Zhou, Thomas Brückel, Oleg Petracic
Oxygen vacancies play a crucial role in controlling the physical properties of complex oxides. In La0.7Sr0.3MnO3-{\delta}, the topotactic phase transition from Perovskite (PV) to Brownmillerite (BM) can be triggered e.g. via oxygen removal during thermal annealing. Here we report on a very efficient thermal vacuum annealing method using aluminum as an oxygen getter material. The topotactic phase transition is characterized by X-ray Diffraction which confirms a successful transition from PV to BM in La0.7Sr0.3MnO3-{\delta} thin films grown via physical vapor deposition. The efficiency of this method is confirmed using La0.7Sr0.3MnO3-{\delta} micron-sized bulk powder. The accompanying transition from the original Ferromagnetic (FM) to an Antiferromagnetic (AF) state and the simultaneous transition from a metallic to an insulating state is characterized using Superconducting Quantum Interference Device (SQUID)-magnetometry and Alternating Current (AC) resistivity measurements, respectively. The near surface manganese oxidation states are probed by synchrotron X-ray Absorption Spectroscopy. Moreover, X-ray Reflectivity, Atomic Force Microscopy and Scanning Transmission Electron Microscopy reveal surface segregation and cation redistribution during the oxygen getter assisted annealing process.
Materials Science (cond-mat.mtrl-sci)
Predicting Trends in $V_{OC}$ Through Rapid, Multimodal Characterization of State-of-the-Art p-i-n Perovskite Devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Amy E. Louks, Brandon T. Motes, Anthony T. Troupe, Axel F. Palmstrom, Joseph J. Berry, Dane W. deQuilettes
Perovskite photovoltaic technologies are approaching commercial deployment, yet single junction and tandem architectures both still have significant room to improve power conversion efficiency and stability. The ability to perform rapid screening of material quality after altering processing conditions is critical to accelerating the optimization and commercialization of perovskite-based technologies. Currently, researchers utilize a wide range of stand-alone metrology tools to isolate sources of power loss throughout a device stack, which can be slow and labor intensive. Here, we demonstrate the use of a multimodal metrology approach to rapidly determine the maximum achievable and predicted open circuit voltages of > 100 perovskite devices during fabrication. Acquisition of these different data are facilitated by combining them into a single integrated measurement platform. We show that these data and automated analysis can be used to rapidly understand and ultimately predict quantitative trends in open circuit voltages of state-of-the-art devices architectures. The data and automated analysis workflow presented provides a reliable approach to quickly identify absorber and charge transport layer combinations that can lead to improved open circuit voltages.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
18 pages, 4 figures
Activity propagation with Hebbian learning
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-29 20:00 EDT
Will T. Engedal, Róbert Juhász, István A. Kovács
We investigate the impact of Hebbian learning on the contact process, a paradigmatic model for infection spreading, which has been also proposed as a simple model to capture the dynamics of inter-regional brain activity propagation as well as population spreading. Each of these contexts calls for an extension of the contact process with local learning. We introduce Hebbian learning as a positive or negative reinforcement of the activation rate between a pair of sites after each successful activation event. Learning can happen either in both directions motivated by social distancing (mutual learning model), or in only one of the directions motivated by brain and population dynamics (source or target learning models). Hebbian learning leads to a rich class of emergent behavior, where local incentives can lead to the opposite global effects. In general, positive reinforcement (increasing activation rates) leads to a loss of the active phase, while negative reinforcement (reducing activation rates) can turn the inactive phase into a globally active phase. In two dimensions and above, the effect of negative reinforcement is twofold: it promotes the spreading of activity, but at the same time gives rise to the appearance of effectively immune regions, entailing the emergence of two distinct critical points. Positive reinforcement can lead to Griffiths effects with non-universal power-law scaling, through the formation of random loops of activity, a manifestation of the ``ant mill” phenomenon.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Populations and Evolution (q-bio.PE)
16 pages, 12 figures
Altermagnetic Shastry-Sutherland fullerene networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-29 20:00 EDT
Jiaqi Wu, Alaric Sanders, Rundong Yuan, Bo Peng
Molecular building blocks provide a versatile platform for realising exotic quantum phases. Using charge neutral, pure carbon fullerene molecules as an example, we design altermagnetic C$ _{40}$ monolayers in Shastry-Sutherland lattice. The resonance structure of one unpaired electron leads to an effective spin-1/2 cluster on both long sides of the molecule, which, after rotating into a 2D rutile-like crystal structure, forms altermagnetic ground state. We show $ d$ -wave spitting of the spin-polarised electronic band structure and strong chiral-split magnon bands. Most interestingly, the effective spin-1/2 clusters form the Shastry-Sutherland model with a rich phase diagram including altermagenti, quantum spin liquid, plaquette, and dimer phases, which can be easily accessed to via moderate bi-axial strains. Our findings present magnetic fullerene monolayers as a tunable platform for exotic quantum magnetism and spintronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Atomic and Molecular Clusters (physics.atm-clus), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
7 pages, 3 figures