CMP Journal 2026-01-02
Statistics
Nature Materials: 2
Nature Physics: 2
Physical Review Letters: 12
arXiv: 110
Nature Materials
Artificial intelligence-driven approaches for materials design and discovery
Review Paper | Computational methods | 2026-01-01 19:00 EST
Mouyang Cheng, Chu-Liang Fu, Ryotaro Okabe, Abhijatmedhi Chotrattanapituk, Artittaya Boonkird, Nguyen Tuan Hung, Mingda Li
Materials design is an important component of modern science and technology, yet traditional approaches rely heavily on trial and error and can be inefficient. Computational techniques, enhanced by modern artificial intelligence, have reshaped the landscape of designing new materials. Among these approaches, inverse design has shown great promise in designing materials that meet specific property requirements. In this Review, we present key computational advances in materials design over the past few decades. We follow the evolution of relevant materials design techniques, from high-throughput forward machine learning methods and evolutionary algorithms, to advanced artificial intelligence strategies such as reinforcement learning and deep generative models. We highlight the paradigm shift from conventional screening approaches to inverse generation driven by deep generative models. Finally, we discuss current challenges and future perspectives of materials inverse design. This Review may serve as a brief guide to the approaches, progress and outlook of designing future functional materials with technological relevance.
Computational methods, Theory and computation
Rational design of high-performance low-loading oxygen reduction catalysts for alkaline fuel cells
Original Paper | Electrocatalysis | 2026-01-01 19:00 EST
Huiqi Li, Rui Zeng, Zixiao Shi, Hongsen Wang, Denis Leshchev, Eli Stavitski, Miriam M. Tellez-Cruz, Weixuan Xu, Mi-Ju Kim, Andrés Molina Villarino, Qihao Li, David A. Muller, Héctor D. Abruña
The lack of mechanistic understanding and catalyst design principles for alkaline electrolytes, especially for the sluggish oxygen reduction reaction, has impeded the advancement of alkaline fuel cells. Here we propose a modified volcano plot and apply this rationale to strategically design Pt nanosheets with PdHx nanosheets substrates. This catalyst exhibited high stability with a specific activity of 1.71 mA cm-2 at 0.95 V versus the reversible hydrogen electrode, surpassing the benchmark of Pt/C by 49-fold. Spectroscopic, electrochemical and electron microscopic characterizations revealed that such performance enhancement originated from tensile-strained Pt{111} facets, improving oxidative stability and suppressing carbon corrosion. In fuel cell testing, the catalyst enabled a peak power density of 1.67 W cm-2 with a loading of 10 µgPGM Cathode cm-2. Further optimization delivered a peak power density of 21.7 W mg-1PGM Cathode+Anode with a total specific catalyst cost US$1.27 kW-1, surpassing the US Department of Energy’s Pt group metal loading and cost targets. This study provides valuable insights into catalyst design for the alkaline oxygen reduction reaction.
Electrocatalysis, Fuel cells
Nature Physics
Two-dimensional non-equilibrium melting of charged colloids
Original Paper | Phase transitions and critical phenomena | 2026-01-01 19:00 EST
Ankit D. Vyas, Philipp W. A. Schönhöfer, Terrence M. Hopkins, Andrew D. Hollingsworth, Stefano Sacanna, Sharon C. Glotzer, Paul Chaikin
Thermodynamic two-dimensional melting has been extensively studied in experiments and simulations, and is well predicted by theory. For systems in equilibrium, this transition is well described by the Kosterlitz-Thouless-Halperin-Nelson-Young theory, where melting is directly linked to the unbinding of topological defects. For driven, non-equilibrium melting and other non-equilibrium phase transitions, the picture is less clear. Here we study the two-dimensional melting of a crystal of charged colloids. By randomly replacing some charged colloids with magnetic colloids, we can melt our system by rotating a fraction of the particles to create non-equilibrium, hydrodynamic random flows and local stresses. We can also melt it thermally by changing the particle number density. We find that an effective temperature approach cannot explain the results of our driven system. Rather, in both experiments and simulations, we observe that plotting the hexatic order parameter and the hexatic correlation’s exponent versus the density of disclinations and dislocations, respectively, yields universal curves. This implies that in our systems, two-dimensional melting depends directly on the density of topological defects and is independent of whether thermal or non-equilibrium forces generate them.
Phase transitions and critical phenomena
Self-induced superradiant masing
Original Paper | Condensed-matter physics | 2026-01-01 19:00 EST
Wenzel Kersten, Nikolaus de Zordo, Oliver Diekmann, Elena S. Redchenko, Andrew N. Kanagin, Andreas Angerer, William J. Munro, Kae Nemoto, Igor E. Mazets, Stefan Rotter, Thomas Pohl, Jörg Schmiedmayer
In cavity quantum electrodynamics and particularly superradiance, emitters are typically assumed to be independent, interacting only through light shared via a common mode. Although such photon-mediated interactions lead to a wide range of collective optical effects, direct dipole-dipole interactions within the emitter ensemble are generally viewed as a source of decoherence. Here we report the role of direct spin-spin interactions as a drive for the superradiant dynamics of a hybrid system of nitrogen-vacancy centre spins in a diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, we observe a train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond. We show that this behaviour arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. We report measurements that exclude other cavity-related effects and perform microscopic simulations that confirm that the observed behaviour is driven by dipole-dipole interactions between the spins. These findings open pathways for exploring complex spin-spin interactions in dense disordered systems and offer possibilities for ultranarrow-linewidth solid-state superradiant masers powered purely by microwave-driven spin control.
Condensed-matter physics, Lasers, LEDs and light sources, Quantum optics
Physical Review Letters
Faster Randomized Dynamical Decoupling
Article | Quantum Information, Science, and Technology | 2026-01-02 05:00 EST
Changhao Yi, Leeseok Kim, and Milad Marvian
We present a randomized dynamical decoupling (DD) protocol that can substantially improve the performance of any given deterministic DD scheme for suppressing coherent noise by using no more than two additional pulses. Our construction is implemented by probabilistically applying sequences of pulses…
Phys. Rev. Lett. 136, 010601 (2026)
Quantum Information, Science, and Technology
Positive Geometry for Stringy Scalar Amplitudes
Article | Particles and Fields | 2026-01-02 05:00 EST
Christoph Bartsch, Karol Kampf, David Podivín, and Jonah Stalknecht
We introduce a new positive geometry, the associahedral grid, which provides a geometric realization of the inverse string theory Kawai-Lewellen-Tye kernel. It captures the full dependence of stringified amplitudes for biadjoint scalar theory, pions in the nonlinear sigma model (NLSM), and the…
Phys. Rev. Lett. 136, 011601 (2026)
Particles and Fields
Simultaneous Probe of the Charm and Bottom Quark Yukawa Couplings Using $t\overline{t}H$ Events
Article | Particles and Fields | 2026-01-02 05:00 EST
A. Hayrapetyan et al. (CMS Collaboration)
A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, , produced in association with a top quark-antiquark pair () is presented. The search is performed with data from proton-proton collisions at , corresponding to an integrated luminosity of
Phys. Rev. Lett. 136, 011801 (2026)
Particles and Fields
Turbulent Multiscale Interactions between Tearing Modes, Trapped-Electron Modes, and Zonal Flows
Article | Plasma and Solar Physics, Accelerators and Beams | 2026-01-02 05:00 EST
T. Jitsuk, M. J. Pueschel, P. W. Terry, and A. Di Siena
Interactions between MHD-scale tearing modes (TMs) and ion-gyroradius-scale trapped-electron modes (TEMs) in a fusion plasma are simulated with global gyrokinetics, using a consistent set of fixed equilibrium profiles. Unstable core TMs nonlinearly couple and transfer energy to smaller-scale stable …
Phys. Rev. Lett. 136, 015101 (2026)
Plasma and Solar Physics, Accelerators and Beams
Quantum Vortices Leave a Macroscopic Signature in the Thermal Background
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Luca Galantucci, Giorgio Krstulovic, and Carlo F. Barenghi
Recent work has highlighted the remarkable properties of quantum turbulence in superfluid helium II, consisting of a disordered tangle of quantized vortex lines which interact with each other and reconnect when they collide. According to Landau's two-fluid theory, these vortex lines move in a surrou…
Phys. Rev. Lett. 136, 016001 (2026)
Condensed Matter and Materials
Common Sublattice-Pure Van Hove Singularities in the Kagome Superconductors $A{\mathrm{V}}{3}{\mathrm{Sb}}{5}$ ($A=\mathrm{K}$, Rb, Cs)
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Yujie Lan, Yuhao Lei, Congcong Le, Brenden R. Ortiz, Nicholas C. Plumb, Milan Radovic, Xianxin Wu, Ming Shi, Stephen D. Wilson, and Yong Hu
Kagome materials offer a versatile platform for exploring correlated and topological quantum states, where Van Hove singularities (VHSs) play a pivotal role in driving electronic instabilities, exhibiting distinct behaviors depending on electron filling and interaction settings. In the recently disc…
Phys. Rev. Lett. 136, 016401 (2026)
Condensed Matter and Materials
Quantum Chemistry for Solids Made Simple on the Clifford Torus
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Amer Alrakik, Gian Luigi Bendazzoli, Stefano Evangelisti, and J. Arjan Berger
We present a general theory to treat periodic solids with quantum-chemistry methods. It relies on two main developments: (1) the modeling of a solid as a Clifford torus, which is a torus that is both periodic and flat, and (2) the introduction of a periodic Gaussian basis set that is compatible with…
Phys. Rev. Lett. 136, 016402 (2026)
Condensed Matter and Materials
Stripe-Nematic Phase of Composite Fermions
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Chengyu Wang, S. K. Singh, C. T. Tai, A. Gupta, L. N. Pfeiffer, K. W. Baldwin, and M. Shayegan
Electronic stripe-nematic phases are fascinating, strongly correlated states characterized by spontaneous rotational symmetry breaking. In the quantum Hall regime, such phases typically emerge at half-filled, high-orbital-index () Landau levels (LLs) where the short-range Coulomb interaction is s…
Phys. Rev. Lett. 136, 016501 (2026)
Condensed Matter and Materials
Orbital Inverse Faraday and Cotton-Mouton Effects in Hall Fluids
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Gabriel Cardoso, Erlend Syljuåsen, and Alexander V. Balatsky
We report two light-induced orbital magnetization effects in quantum Hall (QH) fluids, stemming from their transverse response. The first is a purely transverse contribution to the inverse Faraday effect (IFE), where circularly polarized light induces a dc magnetization by stirring the charged fluid…
Phys. Rev. Lett. 136, 016502 (2026)
Condensed Matter and Materials
Half-Quantized Chiral Edge Current in a $C=1/2$ Parity Anomaly State
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Deyi Zhuo, Bomin Zhang, Humian Zhou, Han Tay, Xiaoda Liu, Zhiyuan Xi, Chui-Zhen Chen, and Cui-Zu Chang
A single massive Dirac surface band is predicted to exhibit a half-quantized Hall conductance, a hallmark of the parity anomaly state in quantum field theory. Experimental signatures of the parity anomaly state have been observed in semimagnetic topological insulator (TI) bilayers, yet w…
Phys. Rev. Lett. 136, 016601 (2026)
Condensed Matter and Materials
Optical Signatures of Quantum Skyrmions
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Sanchar Sharma and Christina Psaroudaki
Magnets have recently emerged as promising candidates for quantum computing, particularly using topologically-protected nanoscale spin textures. While the quantum dynamics of such spin textures has been theoretically studied, direct experimental evidence of their nonclassical behavior remains an ope…
Phys. Rev. Lett. 136, 016701 (2026)
Condensed Matter and Materials
Giant Reversible Piezoelectricity from Symmetry-Governed Stochastic Dipole Hopping
Article | Condensed Matter and Materials | 2026-01-02 05:00 EST
Denan Li, Haofei Ni, Yi Zhang, and Shi Liu
Organic-inorganic hybrid perovskites with giant piezoelectric responses, exemplified by , represent a promising platform for flexible and environmentally friendly electromechanical materials. However, the microscopic origin of such exceptional performance in this weakly polar system has re…
Phys. Rev. Lett. 136, 016801 (2026)
Condensed Matter and Materials
arXiv
Yu-Shiba-Rusinov bound states of exciton condensate
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
SeongJin Kwon, Kyung-Hwan Jin, Jong Eun Han, Siwon Lee, ChoongJae Won, Sang-Wook Cheong, Han Woong Yeom
Quantum condensed states in solids often reveal their fundamental nature via interactions with impurities, as epitomized by Yu-Shiba-Rusinov (YSR) bound states at magnetic impurities in superconductors. Although analogous YSR bound states were predicted within quantum condensates of excitons several decades ago, their existence has been elusive. Here, we directly visualize in-gap electronic states bound to impurities inside an exciton condensate phase of a van der Waals crystal Ta2Pd3Te5, utilizing scanning tunneling microscopy and spectroscopy. We find that the energies of in-gap states are strongly correlated with the excitonic band gap, which is systematically tuned by local strain and carrier injection. Our theoretical analyses reveal that these in-gap states are induced by charge dipoles associated with Ta vacancies through a charge-exciton version of the YSR mechanism. Our findings establish both the YSR physics in exciton condensates and a novel microscopic tool to probe and control quantum properties in exciton condensates persisting up to room temperature.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Acoustic Black Holes in a Shock-Wave Exciton-Polariton Condensate
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Junhui Cao, Jinling Wang, Kirill Bazarov, Chenqi Jin, Huijun Li, Anton Nalitov, Alexey Kavokin
We demonstrate the spontaneous formation of acoustic black holes in exciton-polariton condensates triggered by discontinuous Riemann-type initial conditions. Starting from a quasi-conservative Gross-Pitaevskii model, we show that nonlinear dispersive shock waves naturally generate spatial regions where the local flow velocity exceeds the speed of sound, creating a self-induced transonic interface that functions as an acoustic horizon. Unlike previous schemes relying on externally engineered potentials or pump-loss landscapes, our approach reveals that the intrinsic nonlinear hydrodynamics of polariton fluids alone can lead to horizon formation. Using Whitham modulation theory and numerical simulations, we characterize the transition between subsonic and supersonic regimes and estimate the corresponding surface gravity and Hawking temperature. This mechanism opens a new route toward realizing polariton black holes and studying analogue gravitational effects, including Hawking-like emission, in Bose-Einstein quantum liquids.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), General Relativity and Quantum Cosmology (gr-qc)
Superconductivity from phonon-mediated retardation in a single-flavor metal
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Yang-Zhi Chou, Jihang Zhu, Jay D. Sau, Sankar Das Sarma
We study phonon-mediated pairings in a single-flavor metal with a tunable Berry curvature. In the absence of Berry curvature, we discover an unexpected possibility: $ p$ -wave superconductivity emerging purely from the retardation effect, while the static BCS approximation fails to predict its existence. The gap function exhibits sign-change behavior in frequency (owing to the dynamical structure of the phonon-mediated interaction in the $ p$ -wave channel), and $ T_c$ obeys a BCS-like scaling. We further show that the Berry curvature stabilizes the chiral $ p$ -wave superconductivity and can induce transitions to higher-angular-momentum pairings. Our results establish that the phonon-mediated mechanism is a viable pairing candidate in single-flavor systems, such as the quarter-metal superconductivity observed in rhombohedral graphene multilayers.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
6+5 pages, 4+1 figures
Ergodicity breaking meets criticality in a gauge-theory quantum simulator
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
Ana Hudomal, Aiden Daniel, Tiago Santiago do Espirito Santo, Milan Kornjača, Tommaso Macrì, Jad C. Halimeh, Guo-Xian Su, Antun Balaž, Zlatko Papić
Recent advances in quantum simulations have opened access to the real-time dynamics of lattice gauge theories, providing a new setting to explore how quantum criticality influences thermalization and ergodicity far from equilibrium. Using QuEra’s programmable Rydberg atom array, we map out the dynamical phase diagram of the spin-1/2 U(1) quantum link model in one spatial dimension by quenching the fermion mass. We reveal a tunable regime of ergodicity breaking due to quantum many-body scars, manifested as long-lived coherent oscillations that persist across a much broader range of parameters than previously observed, including at the equilibrium phase transition point. We further analyze the electron-positron pairs generated during state preparation via the Kibble-Zurek mechanism, which strongly affect the post-quench dynamics. Our results provide new insights into nonthermal dynamics in lattice gauge theories and establish Rydberg atom arrays as a powerful platform for probing the interplay between ergodicity breaking and quantum criticality.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
12+13 pages, 5+13 figures
Hedgehog lattices induced by chiral spin interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
We analyze a classical Heisenberg spin model on the simple cubic lattice which is invariant under time reversal and contains multiple chiral spin interactions. The modelled dynamics is appropriate either for local moments coupled to itinerant Weyl electrons, or localized electrons with a strong spin-orbit coupling that would produce a Weyl spectrum away from half filling. Using a Monte Carlo method, we find a robust $ 4Q$ bipartite lattice of hedgehogs and antihedgehogs which melts through a first order phase transition at a critical temperature in certain segments of the phase diagram. The density of hedgehogs is a non-linear function of the Dzyaloshinskii-Moriya interaction, and a linear function of the multiple-spin chiral interaction which plays the fundamental role of a ``magnetic flux’’ or a hedgehog chemical potential. These findings are related to the observations of hedgehog lattices in MnGe, MnSi$ _{1-x}$ Ge$ _x$ and SrFeO$ _3$ , and indirectly support the possible existence of incompressible quantum-disordered hedgehog liquids.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 14 figures
Many-electron characterizations of higher-charge superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
The theoretical understanding of conventional superconductivity as the phonon-assisted formation and condensation of two-electron Cooper pairs is a significant triumph in condensed matter physics. Here, we propose many-electron characterizations of higher-charge superconductivity with Cooper pairs consisting of more than two electrons, by implementing translation symmetrization on parent pair-density-wave-ordered states. In particular, we demonstrate many-electron constructions with vanishing charge-2e sectors, but with sharp signatures in charge-4e or charge-6e expectation values instead. Such characterizations are consistent with previous phenomenology of vestigial order and Ginzburg-Landau theory, yet, instead of point-group-symmetry presumptions, we show that momentum conservation is both vital and sufficient. Our study thus offers a novel, general, and microscopic route to understand and characterize higher-charge superconductivity, including nontrivial experimental signatures such as fractional magnetic flux and period in interferometry, as well as localized Cooper pairs at lattice topological defects.
Superconductivity (cond-mat.supr-con)
7 pages, 5 figures
Mesoporous Thin Films as Nanoreactors for Complex Oxide Nanoparticle-based Devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
S. Passanante, M. Quintero, A. Zelcer, M. S. Moreno, D. Lionello, D. Vega, L. P. Granja
We combine for the first time the properties of ordered mesoporous thin films and complex oxide nanoparticles in the design of new heterostructures, taking advantage of the accessible tridimensional pores network. In this work, we demonstrate the feasibility of synthesizing La0.88Sr0.12MnO3 inside the pores of a mesoporous SiO2 thin film, using pulsed laser deposition. In order to understand the filling process, a set of samples were deposited for three different deposition times, on mesoporous and non-mesoporous SiO2 substrates. Their structural, magnetic, magnetocaloric and electrical transport properties were studied. All the results evidence the presence of the manganite compound inside the pores, which was confirmed by cross-section elemental mapping. X-ray reflectometry shows that it is possible to control the filling of the pores, keeping some accessible porosity. The magnetic behavior suggests the presence of weakly interacting ferromagnetic nanoparticles inside the pores. We provide here a successful strategy for the fabrication of complex oxide nanoparticles arrays with highly controlled size and ordering. Their easy incorporation into micro and nanofabrication procedures unveils direct implications in the field of interfaces and nanoparticle devices as diverse as energy conversion systems, solid oxide fuel cells, spintronics and neuromorphic memristor networks.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Resonant Magneto-phonon Emission by Supersonic Electrons in Ultra-high Mobility Two-dimensional System
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Z. T. Wang, M. Hilke, N. Fong, D. G. Austing, S. A. Studenikin, K. W. West, L. N. Pfeiffer
We investigate resonant acoustic phonon scattering in the magneto-resistivity of an ultra-high mobility two-dimensional electron gas system subject to DC current in the temperature range 10 mK to 3.9 K. For a DC current density of $ \sim$ 1.1 A/m, the induced carrier drift velocity $ v_{drift}$ becomes equal to the speed of sound $ s \sim$ 3 km/s. When $ v_{drift} \gtrsim s$ very strong resonant features with only weak temperature dependence are observed and identified as phonon-induced resistance oscillations at and above the “sound barrier”. Their behavior contrasts with that in the subsonic regime ($ v_{drift} < s$ ) where resonant acoustic phonon scattering is strongly suppressed when the temperature is reduced unless amplified with quasi-elastic inter-Landau-level scattering. Our observations are compared to recent theoretical predictions from which we can extract a dimensionless electron-phonon coupling constant of $ g^{2}$ =0.0016 for the strong non-linear transport regime. We find evidence for a predicted oscillation phase change ‘ effect on traversing the “sound barrier”. Crossing the “sound barrier” fundamentally alters the resulting phonon emission processes, and the applied magnetic field results in pronounced and sharp resonant phonon emission due to Landau level quantization.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Finite-time effects on a first-order irreversible phase transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
The first-order irreversible phase transition (FOIPT) of the ZGB model [Ziff, Gulari, Barshad, Phys. Rev. Lett. \textbf{56} (1986) 2553] for the catalytic oxidation of carbon monoxide is studied numerically in the presence of a slowly time-dependent, spatially uniform carbon monoxide pressure, with standard constant pressure simulations. This method allows us to observe finite-time effects close to the FOIPT, as well as evidence that a dynamic phase transition occurs. The location of this transition is measured very precisely and compared with previous results in the literature.
Statistical Mechanics (cond-mat.stat-mech)
26 pages, 9 figures
Magnetically recoverable MgFe$_2$O$_4$ nanoparticles as efficient catalysts for rapid dye degradation in water
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
A. F. Cabrera, C. E. Rodríguez Torres, P. de la Presa, S. J. Stewart
Monophasic MgFe$ _2$ O$ _4$ nanoparticles synthesized by a simple autocombustion method were assessed as magnetically recoverable catalysts for the degradation of methylene blue (MB) in water. The NPs exhibit a crystallite size of $ \sim$ 9 nm, a band gap of $ \sim$ 2.11 eV, and soft ferrimagnetic behavior, enabling efficient photocatalytic and Fenton-like activity. The effects of irradiation, H$ _2$ O$ _2$ concentration, agitation mode, catalyst loading, and exposure time were systematically evaluated. Rapid and complete MB discoloration was achieved within minutes in the presence of H$ _2$ O$ _2$ , even without illumination, indicating that the process is dominated by a surface-mediated heterogeneous Fenton-like mechanism rather than photocatalysis. Kinetic analysis reveals pseudo-first-order behavior, with rate constants governed by the combined effects of catalyst concentration, oxidant dosage, and dye concentration. Structural stability and excellent recyclability confirm the robustness of the catalyst. These findings position MgFe$ _2$ O$ _4$ nanoparticles as a low-cost, efficient, and reusable material for sustainable wastewater under operationally simple conditions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
29 pages plus 5 pages of supplementary information
Hydrogen localization under thermal gradients in hydride forming metals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Migration of hydrogen and hydride formation under thermal gradient leads to hydrogen redistribution in certain metals. These metals include zirconium, titanium, hafnium and their alloys with tendency to form hydrides. A computational method for hydrogen localization in such metals is presented. The method utilizes the heat flux in a steady state to compute temperature distribution (as input), and hydrogen mass flux under temperature gradient to determine hydrogen distribution both in solid solution and in the hydride phase in a two-dimensional setting. Hydrogen precipitation to hydride is determined by a solid solubility relation with an exponential function of the enthalpy of mixing per a van ‘t Hoff relation. The enthalpy of mixing is treated here as a stochastic variable subject to thermodynamic fluctuations. Henceforth, the Einstein-Boltzmann fluctuation theory is adapted to calculate the spatial distribution of hydrogen in solid solution and in the hydride phase. Hydrogen concentration gets localized in the colder region of the body (Soret effect). We apply the model to the case of a zirconium alloy, Zircaloy-4, which is a material for fuel cladding utilized in pressurized water reactors. Cladding continuously picks up hydrogen due to Zr oxidation during reactor service, which we take into account. Our calculated results, hydrogen concentration profiles are comparable to experimental observations reported in the literature.
Materials Science (cond-mat.mtrl-sci)
17 pages + appendices and references (15 pages) and 6 main figures
Modelling Simul. Mater. Sci. Eng. 33 (2025) 075016
Origin of insulating state in bulk $1T$-TaS$_2$ revealed by out-of-plane dimerization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Achyut Tiwari, Maxim Wenzel, Renjith Mathew Roy, Christian Prange, Bruno Gompf, Martin Dressel
The commensurate charge-density-wave phase in the protoypical transition metal dichalcogenide $ 1T$ -TaS$ _2$ is investigated by temperature and polarization-dependent infrared spectroscopy revealing the fundamentally different charge dynamics parallel and perpendicular to the layers. Supported by density-functional-theory calculations, we demonstrate that the out-of-plane response is governed by a quasi-one-dimensional, Peierls-like dimerization of the two-dimensional star-of-David layers. In particular, our results identifies this dimerization as the primary driving mechanism of the metal-to-insulator transition, ruling out a significant role of electronic correlations.
Strongly Correlated Electrons (cond-mat.str-el)
Competing Antiferromagnetic Phases in Multiferroic Wurtzite Transition-Metal Chalcogenides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Himanshu Mavani, Mohamed Elekhtiar, Kai Huang, Naafis Ahnaf Shahed, Evgeny Y. Tsymbal
Antiferromagnetic (AFM) spintronics offers a pathway toward electrically controllable spin-based devices beyond ferromagnets. Here, we identify wurtzite MnX (X = S, Se, Te) as a family of multiferroic materials hosting competing AFM phases, including altermagnetic, where nonrelativistic spin splitting can be controlled by ferroelectric polarization. Using density-functional theory and atomistic spin-model calculations, we show that all pristine MnX compounds stabilize a stripe type collinear AFM ground state, contrary to earlier predictions of an altermagnetic ground state, with the magnetic order governed by frustrated Heisenberg and biquadratic exchange interactions. We further demonstrate that Cr doping drives a transition to an A-type AFM phase that breaks Kramers spin degeneracy and realizes a g-wave altermagnetic state with large nonrelativistic spin splitting near the Fermi level. Importantly, this spin splitting can be deterministically reversed by polarization switching, enabling electric-field control of altermagnetic electronic structure without reorienting the Neel vector or relying on spin-orbit coupling. The close energetic proximity of the stripe AFM to a noncollinear all-in-all-out configuration indicates that wurtzite MnX lies near a topological magnetic phase with finite scalar spin chirality, which may be stabilized by modest perturbations such as temperature, strain or chemical tuning. The distinct magnetic phases exhibit symmetry selective linear and non-linear Hall responses, providing direct transport signatures of altermagnetism and polarization control. Together, these results establish doped wurtzite MnX as a promising platform for altermagnet-ferroelectric multiferroics and electrically AFM spintronics.
Materials Science (cond-mat.mtrl-sci)
12 pages, 9 figures
Visualizing the dispersions of Fermi polaron and molecule via spin-orbit coupling
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
We propose to measure the dispersions of Fermi polaron and molecule by engineering spin-orbit coupling (SOC) on the impurity, which induces spin flip with finite momentum transfer. The polaron dispersion can be probed at small SOC momentum from the linear response of impurity spin. For molecule, we show that it can be prepared through an adiabatic steady-state evolution when setting SOC momentum as the Fermi momentum of majority bath. By gradually reducing SOC strength to zero, the steady state smoothly evolves to a molecular state with directional symmetry breaking. The corresponding dispersion can then be probed experimentally through the center-of-mass momentum distribution of molecules at finite density. Our scheme reveals a fundamental momentum difference between Fermi polaron and molecule, thereby offering a clear physical picture for their first-order transition in single-impurity system.
Quantum Gases (cond-mat.quant-gas)
5+ pages, 4 figures
Non-stationary dynamics of interspike intervals in neuronal populations
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-01-01 20:00 EST
Luca Falorsi, Gianni V. Vinci, Maurizio Mattia
We study the joint dynamics of membrane potential and time since the last spike in a population of integrate-and-fire neurons using a population density framework. This leads to a two-dimensional Fokker-Planck equation that captures the evolution of the full neuronal state, along with a one-dimensional hierarchy of equations for the moments of the inter-spike interval (ISI). The formalism allows us to characterize the time-dependent ISI distribution, even when the population is far from stationarity, such as under time-varying external input or during network oscillations. By performing a perturbative expansion around the stationary state, we also derive an analytic expression for the linear response of the ISI distribution to weak input modulations.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Neurons and Cognition (q-bio.NC)
10 pages, 4 figures
Assessing generative modeling approaches for free energy estimates in condensed matter
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Maximilian Schebek, Jiajun He, Emil Hoffmann, Yuanqi Du, Frank Noé, Jutta Rogal
The accurate estimation of free energy differences between two states is a long-standing challenge in molecular simulations. Traditional approaches generally rely on sampling multiple intermediate states to ensure sufficient overlap in phase space and are, consequently, computationally expensive. Several generative-model-based methods have recently addressed this challenge by learning a direct bridge between distributions, bypassing the need for intermediate states. However, it remains unclear which approaches provide the best trade-off between efficiency, accuracy, and scalability. In this work, we systematically review these methods and benchmark selected approaches with a focus on condensed-matter systems. In particular, we investigate the performance of discrete and continuous normalizing flows in the context of targeted free energy perturbation as well as FEAT (Free energy Estimators with Adaptive Transport) together with the escorted Jarzynski equality, using coarse-grained monatomic ice and Lennard-Jones solids as benchmark systems. We evaluate accuracy, data efficiency, computational cost, and scalability with system size. Our results provide a quantitative framework for selecting effective free energy estimation strategies in condensed-phase systems.
Statistical Mechanics (cond-mat.stat-mech), Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
Helical Fermi Arc in Altermagnetic Weyl Semimetal
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Yu-Hao Wan, Cheng-Ming Miao, Peng-Yi Liu, Qing-Feng Sun
We investigate the topological properties of modified Dirac Hamiltonians with an altermagnetic mass term and reveal a novel mechanism for realizing altermagnetic Weyl semimetals. Unlike the conventional Wilson mass, the altermagnetic mass drives direct transitions between nontrivial Chern phases of opposite sign and fundamentally reshapes the band inversion surface. By extending this framework to three dimensions, we construct a minimal lattice model that hosts pairs of Weyl nodes as well as coexisting helical Fermi arcs with opposite chirality on the same surface, which is a phenomenon not found in conventional magnetic Weyl semimetals. We further propose a practical scheme to realize these phases in multilayer structures of 2-dimensional Rashba metal with engineered $ d$ -wave altermagnetic order. Our results deepen the theoretical understanding of mass terms in Dirac systems and provide concrete guidelines for the experimental detection and realization of altermagnetic Weyl semimetals.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Phys. Rev. B 112, 235411 (2025)
Non-Hermitian higher-order topological insulators enabled by altermagnet engineering
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Xiang Ji, Dengfeng Wang, Xiaosen Yang
We show that proximitizing an altermagnet to a non-Hermitian topological insulator provides a powerful mechanism for engineering non-Hermitian higher-order topological phases. The altermagnetic order opens a gap at the topological edge states and drives a topological phase transition from a first-order to a second-order topological phase. When combined with nonreciprocal hopping, the system exhibits both the non-Hermitian skin effect and a hybrid skin-topological effect, whereby first-order edge states and second-order corner states accumulate at selected corners of the lattice. We demonstrate that the spectral winding number of the edge states under cylindrical geometry dictates this corner localization and can be reversed by tuning the altermagnetic order. Consequently, both edge and corner modes become directionally controllable. Our results establish altermagnets as a versatile platform for realizing and tuning skin-topological phenomena in non-Hermitian higher-order topological systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
7 page,4 figures
Reentrant Superconductivity from Competing Spin-Triplet Instabilities
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Reentrant superconductivity in strong magnetic fields challenges the conventional expectation that magnetic fields necessarily suppress superconductivity. We show that reentrant superconductivity arises generically from the competition between spinful and spin-polarized superconducting instabilities. Using a minimal Ginzburg-Landau theory with two coupled spin-triplet order parameters, we demonstrate that a magnetic field can reorganize the hierarchy of superconducting instabilities, yielding a characteristic reentrant instability curve independent of microscopic details.
Superconductivity (cond-mat.supr-con)
Ultrafast Exciton-Polariton Transport and Relaxation in Halide Perovskite
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Yuexing Xia, Yin Liang, Zhiyong Zhang, Tian Lan, Xiaotian Bao, Yuyang Zhang, Xin Zeng, Yiyang Gong, Shuai Yue, Wenna Du, Jianhui Fu, Rui Su, Stefan Schumacher, Xuekai Ma, Qing Zhang, Xinfeng Liu
Halide perovskites offer a great platform for room-temperature exciton-polaritons (EPs) due to their strong oscillator strength and large exciton binding energy, promising applications in next-generation photonic and polaritonic devices. Efficient manipulation of EP transport and relaxation is critical for device performance, yet their spatiotemporal dynamics across different in-plane momenta (k//) remain poorly understood due to limitations in experimental access. In this work, we employ energy-resolved transient reflectance microscopy (TRM) combined with the dispersion relation of EPs to achieve high-resolution imaging of EP transport at specific k//. This approach directly reveals the quasi-ballistic transport and ultrafast relaxation of EPs in different k// regions, showcasing diffusion as fast as ~490 cm2/s and a relaxation time of ~95.1 fs. Furthermore, by tuning the detuning parameter, we manipulate the ballistic transport group velocity and relaxation time of EPs across varying k//. Our results reveal key insights into the dynamics of EP transport and relaxation, providing valuable guidance for the design and optimization of polaritonic devices.
Materials Science (cond-mat.mtrl-sci)
Lectures on insulating and conducting quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Two of the iconic phases of the hole-doped cuprate materials are the intermediate temperature pseudogap metal and the lower temperature $ d$ -wave superconductor. Following the prescient suggestion of P.W. Anderson, there were numerous early theories of these phases as doped quantum spin liquids. However, these theories have had difficulties with two prominent observations:
(i) angle-dependent magnetoresistance measurements (ADMR), including observation of the Yamaji effect, present convincing evidence of small hole pockets which can tunnel coherently between square lattice layers, and
(ii) the velocities of the nodal Bogoliubov quasiparticles in the $ d$ -wave superconductor are highly anisotropic, with $ v_F \gg v_\Delta$ .
These lecture notes review how the fractionalized Fermi Liquid (FL\ast) state, which dopes quantum spin liquids with gauge-neutral electron-like quasiparticles, resolves both difficulties. Theories of insulating quantum spin liquids employing fractionalization of the electron spin into bosonic or fermionic partons are discussed. Doping the bosonic parton theory leads to a holon metal theory: while not appropriate for the cuprate pseudogap, this theory is argued to apply to the Lieb lattice. Doping the fermionic parton theory leads to a $ d$ -wave superconductor with nearly isotropic quasiparticle velocities. The construction of the FL\ast state is described using a quantum dimer model, followed by a more realistic description using the Ancilla Layer Model (ALM), which is then used to obtain the theory of the pseudogap and the $ d$ -wave superconductor.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con), High Energy Physics - Theory (hep-th)
60 pages, 32 figures. Advanced School and Conference on Quantum Matter, Dec 1-12, 2025, ICTP, Trieste. Links to lecture videos in manuscript
Correlated 5f electronic states and phase stability in americium under high pressure: Insights from DFT+DMFT calculations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
We investigate the electronic structure of americium (Am) across its four experimentally confirmed high-pressure phases Am-I (P63/mmc), Am-II (Fm-3m), Am-III (Fddd), and Am-IV (Pnma) up to 100 GPa, using density functional theory combined with embedded dynamical mean-field theory. Our results successfully reproduce the prominent localized 5f peak observed in ultraviolet photoelectron spectroscopy around -2.8 eV below the Fermi level in the Am-I phase. While 5f electrons in Am-I and Am-II remain strongly localized, those in Am-III and Am-IV manifest discernible signatures of increased hybridization: a noticeable shift of spectral weight toward the Fermi level, enhanced hybridization strength, and the emergence of distinct multi-peak structures. These changes indicate that 5f electrons begin to participate in bonding and undergo partial delocalization under pressure. Nevertheless, the spectral weight of 5f electrons near the Fermi level in Am-IV remains relatively low, indicating that, compared to U and Pu, Am retains stronger localized 5f electrons even under high pressure. Analysis of the electronic configurations reveals pressure-enhanced valence state fluctuation, characterized by the mixing of 5f5, 5f6, and 5f7 electronic configurations. The X-ray absorption branching ratio further shows that the angular-momentum coupling scheme approaches the jj limit. Additionally, we demonstrate that the stability of the low-symmetry high-pressure phases (Am-III and Am-IV) is governed by a Peierls-like distortion mechanism, which reduces the total energy through symmetry-lowering lattice distortions accompanied by electronic reconstruction. This study offers a new microscopic perspective on high-pressure phase transitions and emergent quantum phenomena in actinide materials.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 7 figures
Kinetic Catalysis of Spontaneous Knotting: How Free Particles Modulate Filament Entanglement
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
Peimo Sun, Yuhan Qin, Zheng Li
Entangled knots form spontaneously in flexible filaments, yet the influence of the surrounding environment on this process is poorly understood. Here we demonstrate that free-moving particles act as kinetic catalysts for spontaneous knotting. Through controlled agitation experiments, we find that a small number of inert beads substantially enhance the probability and accelerate the rate of knot formation. This catalytic effect is non-monotonic: an optimal particle size and concentration that maximizes entanglement, while an excess of particles suppresses knotting by impeding the filament’s dynamics. We develop a stochastic model that quantitatively reproduces this behavior, attributing it to a competition between entanglement-promoting collisions and motion-suppressing drag. Our findings reveal a mechanism for tuning topological complexity, whereby adjusting these environmental agitators can either promote rapid self-assembly or inhibit unwanted entanglement. This work suggests new strategies for controlling filament topology in settings ranging from crowded biological environments to advanced materials processing.
Soft Condensed Matter (cond-mat.soft)
13 pages, 4 figures
Bayesian inference and uncertainty quantification for modeling of body-centered-cubic single crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Seunghyeon Lee, Thao Nguyen, Darby J. Luscher, Saryu J. Fensin, John S. Carpenter, Hansohl Cho
Uncertainties in the high-dimensional space of material parameters pose challenges for the predictive modeling of bcc single crystals, especially under extreme loading conditions. In this work, we identify the key physical assumptions and associated uncertainties in constitutive models that describe the deformation behavior of bcc single crystal molybdenum subjected to quasi-static to shock loading conditions. We employ two representative physics-based bcc single crystal plasticity models taken from our previous work (Nguyen et al. 2021a; Lee et al. 2023b), each prioritizing different key deformation mechanisms. The Bayesian model calibration (BMC) is used for probabilistic estimates of material parameters in both bcc crystal plasticity models. In conjunction with the BMC procedure, the global sensitivity analysis is conducted to quantify the impact of uncertainties in the material parameters on the key simulation results of quasi-static to shock responses. The sensitivity indices at various loading conditions clearly illustrate the physical basis underlying the predictive capabilities of the two distinct bcc crystal plasticity models at low to high strain rates. Both of the calibrated bcc models are then further validated beyond the calibration regime, by which we further identify critical physical mechanisms that govern the transient elastic-plastic responses of single crystal molybdenum under shock loading. The statistical inference framework demonstrated here facilitates the further development of continuum crystal plasticity models that account for a broad range of deformation mechanisms.
Materials Science (cond-mat.mtrl-sci)
Selective Amplification of the Topological Hall Signal in Cr$_2$Te$_3$: The Role of Molecular Exchange Coupling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Suman Mundlia, Ritesh Kumar, Anshika Mishra, Malavika Chandrasekhar, Narayan Mohanta, Karthik V. Raman
Layered magnetic transition-metal chalcogenides (TMCs) are a focal point of research, revealing a variety of intriguing magnetic and topological ground states. Within this family of TMCs, chromium telluride has garnered significant attention because of its excellent tunability in magnetic response, owing to the presence of competing magnetic exchange interactions. We here demonstrate the manipulation of magnetic anisotropy in ultra-thin Cr$ _2$ Te$ _3$ films through growth engineering leading to a controlled transition from in-plane to out-of-plane orientation with an intermediate non-coplanar magnetic ground phase characterized by a topological Hall effect. Moreover, interfacing these films with Vanadyl phthalocyanine (VOPc) molecules prominently enhances the non-coplanar magnetic phase, attributing its presence to the competing interfacial magnetic exchange interactions over the spin-orbit-driven interfacial effects. These findings pave the way for the realization of novel topological spintronic devices through interface-modulated exchange coupling.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Heavy-Tailed Hall Conductivity Fluctuations in Quantum Hall Transitions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Emuna Rimon, Eytan Grosfeld, Yevgeny Bar Lev
We study the full distribution of the zero-temperature Hall conductivity in a lattice model of the IQHE using the Kubo formula across disorder realizations. Near the localization-delocalization transition, the conductivity exhibits heavy-tailed fluctuations characterized by a power-law decay with exponent $ \alpha \approx 2.3$ –$ 2.5$ , indicating a finite mean but a divergent variance. The heavy tail persists across a range of system sizes, correlation lengths of the disorder potential and fillings. Our results demonstrate a breakdown of self-averaging in transport in small, coherent samples near criticality, in agreement with findings in random matrix models of topological indices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Diffusive metal in a percolating Chern insulator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Subrata Pachhal, Naba P. Nayak, Soumya Bera, Adhip Agarwala
Two-dimensional non-interacting fermions without any anti-unitary symmetries generically get Anderson localized in the presence of disorder. In contrast, topological superconductors with their inherent particle-hole symmetry can host a thermal metallic phase, which is non-universal and depends on the nature of microscopic disorder. In this work, we demonstrate that in the presence of geometric disorders, such as random bond dilution, a robust metal can emerge in a Chern insulator with particle-hole symmetry. The metallic phase is realized when the broken links are weakly stitched via concomitant insertion of $ \pi$ fluxes in the plaquettes. These nucleate low-energy manifolds, which can provide percolating conduction pathways for fermions to elude localization. This diffusive metal, unlike those in superconductors, can carry charge current and even anomalous Hall current. We investigate the transport properties and show that while the topological insulator to Anderson insulator transition exhibits the expected Dirac universality, the metal insulator transition displays a different critical exponent $ \nu \approx 2$ compared to a disordered topological superconductor, where $ \nu \approx 1.4$ . Our work emphasizes the unique role of geometric disorder in engineering novel phases and their transitions in topological quantum matter.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el)
6 + 5 pages, 4 + 7 figures, 1 table
Skyrmion and Meron Crystals in Intermetallic Gd$_3$Ru$4$Al${12}$: Microscopic Model Insights into Chiral Phases
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Jiajun Mo, Leandro M. Chinellato, Fletcher Williams, Akiko Kikkawa, Joseph A. M. Paddison, Matthias D. Frontzek, Gabriele Sala, Chris Pasco, Kipton Barros, Taro Nakajima, Taka-hisa Arima, Yasujiro Taguchi, Yoshinori Tokura, Matthew B. Stone, Andrew D. Christianson, Cristian D. Batista, Shang Gao
Topological spin textures in frustrated intermetallics hold great promise for spintronics applications. However, understanding their origin and properties remains a significant challenge due to competing and often long-range interactions mediated by conduction electrons. Here, by combining neutron scattering experiments with theoretical modeling via unprecedented multi-target fits that further incorporate the ferromagnentic resonance data and magnetization curve, we construct a realistic microscopic model for the prototypical intermetallic skyrmion host \text{Gd}$ _3$ \text{Ru}$ _4$ \text{Al}$ _{12}$ . Beyond magnetic frustration, we identify the competition between dipolar interactions and easy-plane single-ion anisotropy as a key ingredient for stabilizing the rich chiral magnetic phases observed in this compound – including a hexagonal skyrmion crystal and two distinct meron crystals. Remarkably, the meron crystal in lower field is revealed to be commensurate with the underlying lattice, and its unique three-meron-one-antimeron spin texture is verified by the polarized x-ray diffraction data. At elevated temperatures, the short-range spin correlations in \text{Gd}$ _3$ \text{Ru}$ _4$ \text{Al}$ _{12}$ are well described by a codimension-two spiral spin-liquid. Perturbations from staggered Dzyaloshinskii-Moriya interactions give rise to chiral fluctuations that account for the temperature and field dependence of the anomalous Hall response. Our results highlight the unique power of neutron scattering, especially when combined with complementary experimental techniques, to unravel complex magnetic phase transitions and provide new insights into the rich variety of topological spin textures in frustrated systems.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
28 pages, 24 figures
Exactly Solvable Models Hosting Altermagnetic Quantum Spin Liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
João Augusto Sobral, Pietro M. Bonetti, Subrata Mandal, Mathias S. Scheurer
We construct spin-$ 3/2$ and spin-$ 7/2$ models on the square-octagon and checkerboard lattices that are exactly solvable with Majorana representations. They give rise to spin-liquid phases with full spin-rotation and lattice-translational symmetries but broken time-reversal symmetry. Although non-zero on elementary plaquettes, the net orbital magnetic moment is guaranteed to vanish as a result of point symmetries; due to the analogy to long-range ordered altermagnets, these types of phases were dubbed altermagnetic spin liquids in [Phys. Rev. Research 7, 023152 (2025)]. For the spin-$ 3/2$ model, we find that a $ g$ -wave altermagnetic spin liquid emerges as the unique ground state. In contrast, the spin-7/2 model exhibits a significantly richer phase diagram, involving different types of chiral spin liquids competing with a $ d$ -wave altermagnetic spin liquid. Finally, we identify and characterize the topological and non-topological excitations, illustrating the rich physics of altermagnetic spin liquids resulting from the interplay of non-trivial topological and symmetry aspects of this novel phase of matter.
Strongly Correlated Electrons (cond-mat.str-el)
8+7 pages, 3+5 figures
Thermal Evolution of Skyrmions in Synthetic Ferrimagnets of Co/Gd Heterostructure for Topological Spintronic Applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Bhuvneshwari Sharma, Soumyaranjan Dash, Shaktiranjan Mohanty, Brindaban Ojha, Debi Rianto, Del Atkinson, Sanjeev Kumar, Subhankar Bedanta
Synthetic ferrimagnetic (SFiM) multilayers offer a versatile platform for hosting skyrmions with tunable magnetic properties, combining the advantages of ferromagnets and antiferromagnets. Unlike synthetic antiferromagnets, SFiMs retain a finite magnetization that allows direct observation of magnetic textures while still benefiting from reduced dipolar fields and a suppressed skyrmion Hall effect. However, a systematic investigation of their temperature and field dependent magnetization evolution, including the labyrinthine-to-skyrmion transition in Co/Gd-based SFiMs, remains less explored. Here, we demonstrate the stabilization of 70 nm-radius skyrmions at room temperature and reveal how the Co and Gd sublattices influence the temperature-dependent net magnetization. Further, we develop a microscopic spin model for SFiM incorporating the relevant magnetic interactions, which reproduces the experimental observations and captures the temperature-dependent magnetic phase evolution. This framework highlights the interplay of fundamental interactions controlling skyrmion stability in SFiM and provides a pathway for engineering heterostructures for topological spintronic applications.
Materials Science (cond-mat.mtrl-sci)
11 pages, 9 Figures
Theoretical Insights into Excitons, Optical Properties, and Nonradiative Recombination Dynamics in M$_6$CSe$_4$ (M = Ca, Sr) Antiperovskite Carbides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Sanchi Monga, Saswata Bhattacharya
Theoretically predicted antiperovskite carbides M$ _6$ CSe$ _4$ (M = Ca, Sr) represent an emerging class of optoelectronic materials with potential relevance for photovoltaic applications. In this work, we present a comprehensive first-principles investigation of their electronic, optical, and excitonic properties, together with non-radiative recombination dynamics. Density functional theory (DFT) and many-body perturbation theory (GW) reveal that both compounds are direct band gap semiconductors with gaps spanning the infrared-visible region. Incorporating electron-hole interactions via the Bethe-Salpeter equation leads to pronounced red-shifts in the first peak of optical spectra, indicative of bound excitons with binding energies of 0.12 eV (Ca$ _6$ CSe$ _4$ ) and 0.20 eV (Sr$ _6$ CSe$ _4$ ), extending over nearly three unit cells in all directions. Time-dependent DFT combined with nonadiabatic molecular dynamics simulations at 300 K reveals pronounced lattice fluctuations in Ca$ _6$ CSe$ _4$ , resulting in 38% larger band gap variations and 28% faster electronic decoherence. Together with 53% weaker nonadiabatic couplings, these effects yield non-radiative recombination lifetimes approximately eleven times longer than in Sr$ _6$ CSe$ _4$ . Overall, our results identify M$ _6$ CSe$ _4$ carbides as promising lead-free photovoltaic materials, with Ca$ _6$ CSe$ _4$ exhibiting superior optoelectronic properties and carrier dynamics that motivate further experimental investigation.
Materials Science (cond-mat.mtrl-sci)
Chiral dual spin currents field-free perpendicular switching by altermagnet RuO2
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Gengchen Meng Qi Sun, Zhicheng Xie, Yumin Yang, Yu Zhang, Na Lei, Dahai Wei
Conventional spintronic mechanisms, such as spin-transfer and spin-orbit torques based on the spin current, rely on breaking time-reversal symmetry to manipulate magnetic moments. In contrast, for spatially separated dual spin currents, the time-reversal-invariant vector chirality emerges as a critical factor governing magnetization dynamics. Here, we investigate field-free perpendicular magnetization switching in an altermagnet RuO2/ferromagnet/heavy metal Pt trilayer, driven by chiral dual spin currents (CDSC). We demonstrate that the chirality of these dual spin currents acts as the deterministic role in breaking out-of-plane symmetry. Leveraging the intrinsic spin-splitting effect of the d-wave altermagnet to generate an x-polarized spin component, the interplay of non-collinear spin currents from two adjacent layers induces a helical magnetic texture within the intermediate layer. The resulting intralayer exchange coupling manifests as an effective in-plane magnetic field, facilitating deterministic switching. This distinct physical picture, validated by switching measurements and micromagnetic simulations, reveals that the switching polarity is dictated by chirality rather than charge current polarity. Characterized by the novel symmetry and low power consumption, CDSC offers a promising paradigm for next-generation high-performance spintronic architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dynamical probing of superfluidity and shear rigidity in different phases of a dipolar Bose-Einstein condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
Soumyadeep Halder, Hari Sadhan Ghosh, Axel Pelster, B. Prasanna Venkatesh
We show that a sudden change in the polarization direction of the magnetic dipole moments of the atoms in a dipolar Bose-Einstein condensate (BEC) can serve as a useful probe to sense its superfluid and solid-like properties. We find that for small angular deviation of the polarization direction, actuated for instance by modifying an external magnetic field, the superfluid state undergoes an undamped scissors mode oscillation, a characteristic signature of superfluidity. In contrast, both the droplet and supersolid states exhibit a scissors-mode oscillation, which is effectively damped due to multiple closely spaced frequency components. Notably, we find that this damping rate provides a direct quantitative measure for the rigidity of different phases of a dipolar BEC. Furthermore, there exists a maximum angular deviation of the polarization direction, beyond which the droplet and the supersolid states undergo a permanent deformation i.e., we find an analog of the usual elastic to plastic phase transition of solids. We characterize this transition numerically using the fidelity of the condensate wavefunction with the ground state as well as the droplet width and periodicity of the supersolid density of the condensate which are experimentally accessible. Thus, the technique introduced here can be an important experimental benchmark to identify and characterize the superfluid and solid properties of different phases of dipolar BECs.
Quantum Gases (cond-mat.quant-gas)
16 pages, 9 figures
Atomic-scale visualization of d-wave altermagnetism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Daran Fu, Liu Yang, Kebin Xiao, Yuyang Wang, Zhiwei Wang, Yugui Yao, Qi-Kun Xue, Wei Li
Altermagnetism is a newly discovered fundamental form of magnetic order, distinct from conventional ferromagnetism and antiferromagnetism. It uniquely exhibits no net magnetization while simultaneously breaking time-reversal symmetry, a combination previously thought to be mutually exclusive. Although its existence and signatures in momentum space have been established, the direct real-space visualization of its defining rotational symmetry breaking has remained a missing cornerstone. Here, using scanning tunnelling microscopy, we present atomic-scale imaging of electronic states in the candidate material CsV2Se2O. We directly visualize the hallmark symmetry breaking in the form of unidirectional electronic patterns tied to magnetic domain walls and spin defects, as well as elliptical charging rings surrounding those defects. These observed electronic states are all linked to the underlying alternating spin texture. Our work provides the foundational real-space evidence for altermagnetism, moving the field from theoretical and momentum-space probes to direct visual confirmation; thereby opening a path to explore how this unconventional magnetic order couples to and controls other quantum electronic states.
Materials Science (cond-mat.mtrl-sci)
17 pages, 5 figures
Linear exciton Hall and Nernst effects in monolayer two-dimensional semiconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Weilong Guo, Lianguo Li, Qingjun Tong, Ci Li
This paper focuses on the study of linear exciton Hall and Nernst effects in monolayer two-dimensional (2D) semiconductors, employing the semi-classical transport theory. By deriving the exciton Berry curvature in momentum space for a general inhomogeneous 2D system, we establish its dependence on the Berry curvature and the effective mass of electron and hole. As illustrative examples, the exciton Hall effect in monolayer transition metal dichalcogenides (TMDs) and black phosphorus (BP) are calculated. For these materials, we demonstrate that a linear Hall (Nernst) exciton current with the non-zero Berry curvature is strictly forbidden by the symmetries. This finding aligns with earlier experimental observations on the exciton Hall effect in MoSe$ _2$ . In contrast, a strong anisotropy in BP leads to a net linear Hall current of excitons, exhibiting a relatively large value and resembling an anomalous Hall effect rather than a valley Hall effect. Our work reveals that the specific symmetry of 2D materials can induce a significant linear exciton Hall (Nernst) effect even without Berry curvature, which is normally forbidden with non-zero Berry curvature in the monolayer 2D material. This observation holds promise for future optoelectronic applications and offers exciting possibilities for experimental exploration.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
8 pages, 3 figures
The effect of germanium sublayer on the native corrosion of ultrathin copper films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Vladimir A. Vdovin, Ivan I. Pyataikin
To examine the process of native corrosion of ultrathin (about 10 nm) copper films deposited on quartz glass substrates $ (SiO_2)$ with and without a germanium sublayer, the time dependences of the microwave reflection coefficient $ R$ and direct current electrical resistivity $ \rho$ of such samples exposed to air at room temperature have been studied. Under these conditions, the thickness of the oxide layer $ d$ on $ Cu/SiO_2$ films was found to increase over time $ t$ according to a parabolic law, which is in contradiction with the predictions of existing theories of copper oxidation. A model is proposed that explains this behavior of $ d(t)$ by the diffusion of atomic oxygen along the boundaries of oxide grains towards the copper film with its subsequent oxidation. The $ R$ and $ \rho$ of $ Cu/Ge/SiO_2$ films were found to degrade much more slowly than similar characteristics of $ Cu/SiO_2$ films of the same thickness. The high corrosion resistance of $ Cu/Ge/SiO_2$ films is explained by the peculiarities of $ Ge$ redistribution during the growth of the copper film on a germanium sublayer. The long-term retention by $ Cu/Ge/SiO_2$ films of their characteristics allows them to be recommended as a cheap replacement for gold coating in electromagnetic interference protection devices.
Materials Science (cond-mat.mtrl-sci)
37 pages, 6 figures
High bosonic Bott index and transport of multi-band topological magnons
New Submission | Other Condensed Matter (cond-mat.other) | 2026-01-01 20:00 EST
Magnons are bosonic quasiparticles in magnetically ordered systems. Bosonic Bott index has been affirmed as a real-space topological invariant for a two-band ferromagnetic model. In this work,we theoretically investigate the topology and transport of magnons in a multi-band bosonic Kagome ferromagnetic model. We demonstrate the validity of the bosonic Bott indices of values larger than 1 in multi-band magnonic systems by showing the agreement with Chern numbers in the clean limit and the bulk-boundary correspondence during the topological phase transition. For the high Bott index phase, the disorder-induced topological phase transition occurs in a multi-step manner. Using a generalized Landauer-Buttiker formalism, we reveal how the magnon transport depends on Gilbert damping and disorder under coherent excitation or temperature difference. The results further justify the bosonic Bott index as a robust real-space topological invariant for multi-band magnonic systems and provide insights into the transport of topological magnons.
Other Condensed Matter (cond-mat.other), Disordered Systems and Neural Networks (cond-mat.dis-nn)
12 pages, 9 figures
Topological spin textures in an antiferromagnetic monolayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Felix Zahner, Tim Drevelow, Roberto Lo Conte, Roland Wiesendanger, Stefan Heinze, Kirsten von Bergmann
Topological spin structures such as magnetic skyrmions are of fundamental interest and promising for various types of applications in spintronics. Skyrmions have been predicted to emerge also in antiferromagnetic materials where they exhibit superior transport properties. They were experimentally revealed in synthetic antiferromagnets, however, still remain elusive in intrinsic antiferromagnets. Here, we demonstrate the stabilization of topological spin structures in an antiferromagnetic monolayer. Using spin-polarized scanning tunneling microscopy, we observe an antiferromagnetic spin spiral in the Mn monolayer and a collinear antiferromagnetic state in the Mn double-layer on Ta(110). Near the boundary to the double-layer half-skyrmions form in the monolayer as revealed in combination with first-principles calculations and micromagnetic simulations. Our work shows how the topological state in antiferromagnetic material systems can be controlled by the configuration within a lateral heterostructure, resulting in trivial non-coplanar states or antiferromagnetic skyrmions.
Materials Science (cond-mat.mtrl-sci)
12 pages, 7 figures
Soft x-rays with Orbital Angular Momentum for resonant scattering experiments at the SOLEIL synchrotron
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Pietro Carrara, Franck Fortuna, Renaud Delaunay, Joan Vila-Comamala, Benedikt Rösner, Christian David, Stefania Pizzini, Clément Fourniols, Laurent Vila, Matteo Pancaldi, Carlo Spezzani, Flavio Capotondi, Pierre Nonnon, Mauro Fanciulli, Thierry Ruchon, Nicolas Jaouen, Horia Popescu, Maurizio Sacchi
The paper presents a comprehensive description of a new setup implemented and commissioned at the SEXTANTS beamline of the SOLEIL synchrotron for absorption and scattering experiments with x-ray beams carrying an orbital angular momentum, also known as twisted x-ray beams. Two alternative methods have been implemented, based on the use of either spiral zone plates or fork gratings devices, and we show how they can be used for both defining and assessing the orbital angular momentum of an x-ray beam. We show also how multiple devices can be used in sequence to define an integer arithmetic of the orbital angular momentum of the final x-ray beam. Finally, we report the results of the first resonant scattering pilot experiments in transmission and reflection mode, intended to assess the feasibility of future users measurements. The availability of twisted soft x-rays complements the range of experimental techniques in elastic, resonant and coherent scattering available at the SEXTANTS beamline of the SOLEIL synchrotron.
Materials Science (cond-mat.mtrl-sci), Accelerator Physics (physics.acc-ph)
23 pages, 14 figures
Extending the Growth Temperature-N Concentration Regime Through Pd Doping in Fe4N Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Rohit Kumar Meena, Akhil Tayal, Andrei Gloskovskii, Mukul Gupta
Fe4N is a well-known anti-perovskite compound exhibiting high magnetization, high chemical stability, low coercivity, high Curie temperature, and high spin-polarization ratio. Therefore, it is a viable candidate for applications in spintronic and magnetic storage devices. However, the Fe4N phase is formed in a narrow substrate temperature (Ts)-N concentration (Nc) regime in the phase diagram of Fe-N. It has been observed that a slight N deficiency will lead to impurity of alpha-Fe, and some N efficiency would result in epsilon-Fe3N phase. Through this work, it has been demonstrated that the doping of Pd can be suitably utilized to extend the Ts-Nc regime for the growth of Fe4N thin films. EXAFS analysis indicate that Pd atoms are substituting corner Fe atoms. Magnetization measurements reveal that the saturation magnetization reduces nominally with Pd doping up to 13 at.%. Therefore, it is foreseen that Pd doping is effective in extending the Fe4N phase formation regime without a significant impact on its structural, electronic, and magnetic properties.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Increased Covalence and V-center mediated Dark Fenton-Like Reactions in V-doped TiO2: Mechanisms of Enhanced Charge-Transfer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Manju Kumari, Dilip Sasmal, Suresh Chandra Baral, Maneesha P, Poonam Singh, Abdelkrim Mekki, Khalil Harrabi, Somaditya Sen
Tuning the valence state and electronic structure of catalytically active sites is crucial for improving Fenton and Fenton-like reactions, which rely on the efficient activation of the H2O2 molecule. Pure TiO2, however, has inadequate activity towards the H2O2 activation and is often constrained by the intrinsic electronic limitations of pristine TiO2. Herein, a rational approach has been demonstrated to improve the Fenton-like catalytic performance of TiO2 through multivalent vanadium (V) doping. A comprehensive characterization using X-Ray Diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, X-Ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), and Density functional theory (DFT) reveals that V incorporation substantially alters the electronic structure of TiO2. The DFT results, supported by experimental data, indicate that V doping enhances Ti-O covalence and introduces mid-gap states, resulting in a reduced band gap and improved charge transfer. XPS confirms the coexistence of multiple oxidation states of V, which serve as active centres for activating H2O2 and generating OH radicals. As a result, V-doped TiO2 exhibits significantly enhanced dark-catalytic activity in degrading the organic dye Rhodamine B (RhB). Overall, this study provides fundamental insights into multivalent-cation-induced valence state and electronic structure modulation in TiO2, offering a promising strategy for designing high-performance catalysts via defect engineering for sustainable environmental remediation.
Materials Science (cond-mat.mtrl-sci)
Non-Euclidean interfaces decode the continuous landscape of graphene-induced surface reconstructions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Li-Qun Shen, Hao-Jin Wang, Mengzhao Sun, Yang Xiang, Xin-Ning Tian, Yue Chai, Yue Yang, Feng Ding, Xiao Kong, Marc-Georg Willinger, Zhu-Jun Wang
Interfacial reconstruction between two-dimensional (2D) materials and metal substrates fundamentally governs heterostructure properties, yet conventional flat substrates fail to capture the continuous crystallographic landscape. Here, we overcome this topological limitation using non-Euclidean interfaces-curved 2D graphene-copper surfaces as a model system-to traverse the infinite spectrum of lattice orientations. By integrating multimodal microscopy with a deep-learning-enhanced dimensional upscaling framework, we translate 2D scanning electron microscopy (SEM) contrast into quantitative three-dimensional (3D) morphologies with accurate facet identification. Coupling these observations with machine-learning-assisted density functional theory, we demonstrate that reconstruction is governed by a unified thermodynamic mechanism where high-index facets correspond to specific local minima in the surface energy landscape. This work resolves the long-standing complexity of graphene-copper faceting and establishes non-Euclidean surface topologies as a generalizable paradigm for decoding and controlling interfacial reconstruction in diverse metal-2D material systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
High-Performance KV$_3$Sb$_5$/WSe$_2$ van der Waals Photodetectors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Yang Yang, Shaofeng Rao, Yuxuan Hou, Jiabo Liu, Deng Hu, Yunfei Guo, Jianzhou Zhao, Hechen Ren, Zhiwei Wang, Fan Yang
Kagome metals AV$ _3$ Sb$ _5$ (A = K, Rb, Cs) have recently emerged as a promising platform for exploring correlated and topological quantum states, yet their potential for optoelectronic applications remains largely unexplored. Here, we report high-performance photodetectors based on van der Waals KV$ _3$ Sb$ _5$ /WSe$ _2$ heterojunctions. A high-quality Schottky interface readily forms between KV$ _3$ Sb$ _5$ and WSe$ _2$ , enabling efficient separation and transport of photoinduced carriers. Under 520 nm illumination, the device achieves an open-circuit voltage up to 0.6 V, a responsivity of 809 mA/W, and a fast response time of 18.3 us. This work demonstrates the promising optoelectronic applications of Kagome metals and highlights the potential of KV$ _3$ Sb$ _5$ -based van der Waals heterostructures for high-performance photodetection.
Materials Science (cond-mat.mtrl-sci)
16 pages including Supporting Information
Sound Wave in the Backreaction Affected Spacetime in Analogue Gravity Based on Number-Conserving Approach
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
It is shown that the sound wave in the backreaction affected dynamical spacetime follows the equations for a massive scalar field in a analogue spacetime using number-conserving approach. Even with backreaction, the analogue metric is in the same form to the case without backreaction. The sound velocity, fluid density, and fluid velocity are defined with small correction to include the backreaction effect. Moreover, the modification of classical fluid dynamical equations by the backreaction introduces spacetime dependent mass. For a finite-size homogeneous quasi-one dimensional Bose gas, we find that the backreaction increase the UV divergence of the equal position correlation function. Moreover, in this model, we see that the backreaction increase the correlation in a finite region and decrease the correlation in far region.
Quantum Gases (cond-mat.quant-gas), General Relativity and Quantum Cosmology (gr-qc)
Semiclassical theory for proximity-induced superconducting systems with spin-orbit coupling
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Zhen-Cheng Liao, Cong Xiao, Zhi Wang, Qian Niu
We develop a semiclassical theory of superconducting quasiparticles for proximity-induced superconducting systems, where spin-orbit coupling plays a critical role in shaping the quasiparticle dynamics. We reveal the structure of superconducting Berry curvatures in such systems, and derived the superconducting Berry curvature induced thermal Edelstein effect and spin Nernst effect. We calculate these two thermo-spin responses with model systems where Rashba spin-orbit coupling, proximity induced superconductivity, and ferromagnetic order are coexisting.
Superconductivity (cond-mat.supr-con)
The long paper that is joint submitted with arXiv: 2412.08451
Tritium accumulation and ozone decontamination of tungsten and beryllium
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Dominic Batzler, Robin Größle, Philipp Haag, Elizabeth Paine, Marco Röllig, Marie-Christine Schäfer, Marius Schaufelberger, Kerstin Trost
Tritium adsorption on surfaces creates a variety of issues, ranging from the fields of fusion applications to small and large-scale laboratory experiments using tritium. The extent to which tritium accumulates on surfaces is generally material-dependent and must be determined through experiments. Additionally, this surface contamination necessitates the implementation of appropriate decontamination procedures, preferably in-situ. A suitable method could be exposure to ozone during UV irradiation. However, it is currently not known if both components are necessary for the decontamination. At Tritium Laboratory Karlsruhe, both questions on contamination and decontamination can be addressed using a single experimental setup. With this, it is possible to expose solid samples to gaseous tritium to measure the temporal activity evolution. Furthermore, the system can be filled with dry air, and dry air containing ozone to explore their decontamination effect. Both measurement modes were applied to beryllium and tungsten samples, which were chosen for their relevance in fusion. The beryllium surface was observed to accumulate tritium more than four times faster than tungsten when exposed to gaseous tritium. Concerning the decontamination, without simultaneous UV irradiation, exposure to ozone did not have any distinct effect on the surface activity compared to simply using dry air. This leads to the conclusion that UV illumination of the surfaces is required to achieve a significant decontamination factor.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
12 pages, 5 figures
Orbital magnetic octupole in crystalline solids and anomalous Hall response to a nonuniform electric field
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Magnetic multipole moments beyond dipoles have emerged as key descriptors of unconventional electromagnetic responses in crystalline solids. However, a gauge-invariant bulk expression for orbital magnetic multipole moments has remained elusive, hindering a unified understanding of their physical consequences. Here we formulate a gauge-invariant expression for the orbital magnetic octupole moment in periodic crystals and investigate its behavior in a minimal model of $ d$ -wave altermagnets. We show that the orbital magnetic octupole is naturally linked to a higher-rank Hall response induced by spatially nonuniform electric fields, leading to a generalized Středa-type relation. Finally, we demonstrate that such a Hall response can arise even when symmetry forbids the conventional anomalous Hall effect against uniform electric fields, thereby providing an illustrative response characteristic to altermagnets.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Geometry induced net spin polarization of $d$-wave altermagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Altermagnets exhibit spin-split electronic band structures despite having zero net magnetization, making them attractive for field-free spintronic applications. In this work, we show that a finite rectangular altermagnetic sample can acquire a net spin polarization purely due to its geometry. This effect arises from the interplay between the anisotropic, spin-resolved Fermi contours of an altermagnet and the discrete sampling of momentum space imposed by unequal sample dimensions. By explicitly counting occupied states, we demonstrate that rectangular samples with $ L_x \neq L_y$ host a finite spin polarization, which vanishes in the symmetric limit $ L_x=L_y$ and in the thermodynamic limit. We further show that this geometry-induced spin polarization can be directly probed in transport measurements. In the tunneling regime, the ratio of spin to charge conductance exhibits characteristic square-like patterns as a function of sample dimensions, faithfully reflecting the underlying spin polarization. In addition, transport across ferromagnet–altermagnet–ferromagnet junctions reveals an asymmetric magnetoresistance with respect to reversal of the Zeeman field, providing an independent transport signature of the finite spin polarization. Our results establish geometry as an effective control parameter for spin polarization in altermagnets and suggest a viable route for exploiting finite-size effects in mesoscopic altermagnetic spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
4 pages, 4 captioned figures. Comments are welcome
Mixing, segregation, and collapse transitions of interacting copolymer rings
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
EJ Janse van Rensburg, E Orlandini, MC Tesi, SG Whittington
A system of two self and mutual interacting ring polymers, close together in space, can display several competing equilibrium phases and phase transitions. Using Monte Carlo simulations and combinatorial arguments on a corresponding lattice model, we determine three equilibrium phases, two in which the rings segregate in space and are either extended (the segregated-expanded phase) or compact (the segregated-collapsed phase). The third is a mixed phase where the rings interpenetrate. The corresponding phase boundaries are located numerically and their critical nature is discussed. Finally, by looking at the topological properties of the three phases, we show that the two rings are likely to be linked in the mixed phase and knotted in the segregated-collapsed phase.
Soft Condensed Matter (cond-mat.soft)
Magnetic-Field-Driven Insulator-Superconductor Transition in Rhombohedral Graphene
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Jian Xie, Zihao Huo, Zhimou Chen, Zaizhe Zhang, Kenji Watanabe, Takashi Taniguchi, Xi Lin, Xiaobo Lu
Recent studies of rhombohedral multilayer graphene (RMG) have revealed a variety of superconducting states that can be induced or enhanced by magnetic fields, reinforcing RMG as a powerful platform for investigating novel superconductivity. Here we report an insulator-superconductor transition driven by in-plane magnetic fields B|| in rhombohedral hexalayer graphene. The upper critical in-plane field of 2T violates the Pauli limit, and an analysis based on isospin symmetry breaking supports a spin-polarized superconductor. At in-plane B = 0, such spin-polarized superconductor transitions into an insulator, exhibiting a thermally activated gap of 0.1 meV. In addition, we observe four superconducting states in the hole-doped regime, as well as phases with orbital multiferroicity near charge neutrality point. These findings substantially enrich the phase diagram of rhombohedral graphene and provide new insight into the microscopic mechanisms of superconductivity
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Tethering effects on first-passage variables of lattice random walks in linear and quadratic focal point potentials
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Diffusion in a confining potential offers a minimal setting to understand the interplay between random motion and deterministic forces driving a particle towards a focal point or potential minimum. In continuous space and time, two extensively studied examples are Brownian motion in a linear (V-shaped) or a quadratic (U-shaped) potential. The deterministic bias towards the minimum is represented, respectively, by a constant force for the former and by an elastic restoring force that increases proportionally with distance for the latter. Surprisingly, unlike Brownian walks, random walks under focal point potentials in discrete space and time have received little attention. Here, we bridge this gap by analysing the dynamics of lattice random walkers in the presence of a V-shaped potential, both in a finite and an infinite spatial domain, and a finite U-shaped potential. For the V-potential in unbounded space, we find the generating function of the occupation probability and analyse the time dependence of the mean number of distinct sites visited, demonstrating that its long-time growth is logarithmic. We also study the first-passage probability and show that its mean may display a minimum as a function of bias strength, depending on the location of the initial and target sites relative to the focal point. Qualitatively similar dependencies in the first-passage probability and its mean appear for the finite U-potential. As a comparative analysis to the U-potential, we construct the bounded V-potential and superimpose in both cases a resetting process, in which the walker returns at random times to a site distinct from the focal point with some probability. We quantify the different effects of resetting on the steady-state probability and the first-passage dynamics in the two cases, and show a motion-limited regime emerges even for relatively moderate resetting probabilities.
Statistical Mechanics (cond-mat.stat-mech)
23 pages, 11 figures
“X-ray Coulomb Counting” to understand electrochemical systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Chuntian Cao, Hans-Georg Steinrück
Electrochemical systems are important for a sustainable and defossilized energy system of the future. While accurate and precise, the corresponding electrochemical measurements, in which many reactions may occur simultaneously, often do not contain enough information to understand the underlying mechanism and processes. This information, however, is crucial towards rational materials and devices as well as process development and for inventing new concepts. We introduce explicitly the concept of “X-ray Coulomb Counting” in which X-ray methods are used to quantify on an absolute scale how much charge is transferred into which reactions during the electrochemical measurements. This allows to interpret the electrochemical measurements in detail and obtain the desired phenomenological and mechanistic understanding. We show a few recent examples from the Li-ion battery literature in which the concept of X-ray Coulomb Counting was employed to obtain foundational understanding.
Materials Science (cond-mat.mtrl-sci)
Assembling a Bose-Hubbard superfluid from tweezer-controlled single atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
William J. Eckner, Theodor Lukin Yelin, Alec Cao, Aaron W. Young, Nelson Darkwah Oppong, Lode Pollet, Adam M. Kaufman
Quantum simulation relies on the preparation and control of low-entropy many-body systems to reveal the behavior of classically intractable models. The development of new approaches for realizing such systems therefore represents a frontier in quantum science. Here we experimentally demonstrate a new protocol for generating ultracold, itinerant many-body states in a tunnel-coupled two-dimensional optical lattice. We do this by adiabatically connecting a near-ground-state-cooled array of up to 50 single strontium-86 atoms with a Bose-Hubbard superfluid. Through comparison with finite-temperature quantum-Monte-Carlo calculations, we estimate that the entropy per particle of the prepared many-body states is approximately $ 2 k_B$ , and that the achieved temperatures are consistent with a significant superfluid fraction. This represents the first time that itinerant many-body systems have been prepared from rearranged atoms, opening the door to bottom-up assembly of a wide range of neutral-atom and molecular systems.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Les Houches Lectures Notes on Tensor Networks
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Bram Vancraeynest-De Cuiper, Weronika Wiesiolek, Frank Verstraete
Tensor networks provide a powerful new framework for classifying and simulating correlated and topological phases of quantum matter. Their central premise is that strongly correlated matter can only be understood by studying the underlying entanglement structure and its associated (generalised) symmetries. In essence, tensor networks provide a compressed, holographic description of the complicated vacuum fluctuations in strongly correlated systems, and as such they break down the infamous many-body exponential wall. These lecture notes provide a concise overview of the most important conceptual, computational and mathematical aspects of this theory.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
Comments welcome
Evidence of Spin-Valley Coupling in Dirac Material BaMnBi2 Probed by Quantum Hall Effect and Nonlinear Hall Effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Subin Mali, Yingdong Guan, Lujin Min, David Graf, Zhiqiang Mao
Valleytronics is a rapidly advancing field that explores the use of the valley degree of freedom in electronic systems to encode and process information. It relies on electronic states with spin valley locking, first predicted and observed in monolayer transition metal dichalcogenides such as MoS2. However, very few bulk materials have been reported to host spin valley locked electronic states. In this work, we present experimental evidence for a predicted, unique spin valley locked electronic state generated by Bi zigzag chains in the layered compound BaMnBi2. We observe remarkable quantum transport properties in this material, including a stacked quantum Hall effect (QHE) and a nonlinear Hall effect (NLHE). From the analysis of the QHE, we identify a spin valley degeneracy of four, while the NLHE provides supporting evidence for the anticipated valley contrasted Berry curvature, a typical signature of a spin valley locked state. This spin valley locked state contrasts with that observed in the sister compound BaMnSb2, where the degeneracy is two. This difference arises from significant variations in their orthorhombic crystal structures and spin orbit coupling. These findings establish a new platform for exploring coupled spin valley physics in bulk materials and highlight its potential for valleytronic device applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
24 pages, 4 figures
Using Particle Shape to Control Defects in Colloidal Crystals on Spherical Interfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
Gabrielle N. Jones, Philipp W.A. Schönhöfer, Sharon C. Glotzer
Spherical particles confined to a sphere surface cannot pack densely into a hexagonal lattice without defects. In this study, we use hard particle Monte Carlo simulations to determine the effects of continuously deformable shape anisotropy and underlying crystal lattice preference on inevitable defect structures and their distribution within colloidal assemblies of hard rounded polyhedra confined to a closed sphere surface. We demonstrate that cube particles form a simple square assembly, overcoming lattice/topology incompatibility, and maximize entropy by distributing eight three-fold defects evenly on the sphere. By varying particle shape smoothly from cubes to spheres we reveal how the distribution of defects changes from square antiprismatic to icosahedral symmetry. Congruent studies of rounded tetrahedra reveal additional varieties of characteristic defect patterns within three, four, and six-fold symmetric lattices. This work has promising implications for programmable defect generation to facilitate different vesicle buckling modes using colloidal particle emulsions.
Soft Condensed Matter (cond-mat.soft)
26 pages (12 main manuscript; 14 SI), 21 figures (5 main manuscript; 16 SI)
Insights Into Radiation Damage in YBa$_2$Cu$3$O${7-δ}$ From Machine-Learned Interatomic Potentials
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Ashley Dicksona, Niccolò Di Eugenio, Federico Ledda, Daniele Torsello, Francesco Laviano, Flyura Djurabekova, Jesper Byggmästar, Mark R. Gilbert, Duc Nguyen-Manh, Erik Gallo, Antonio Trotta, Davide Gambino, Samuel T. Murphy
Accurate prediction of radiation damage in YBa$ _2$ Cu$ 3$ O$ {7-\delta}$ (YBCO) is essential for assessing the performance of high-temperature superconducting (HTS) tapes in compact fusion reactors. Existing empirical interatomic potentials have been used to model radiation damage in stoichiometric YBCO, but fail to describe oxygen-deficient compositions, which are ubiquitous in industrial Rare-Earth Barium Copper Oxide conductors and strongly influence superconducting properties. In this work, we demonstrate that modern machine-learned interatomic potentials enable predictive modelling of radiation damage in YBCO across a wide range of oxygen stoichiometries, with higher fidelity than previous empirical models. We employ two recently developed approaches: an Atomic Cluster Expansion (ACE) potential and a tabulated Gaussian Approximation Potential (tabGAP). Both models accurately reproduce Density Functional Theory (DFT) energies, forces, and threshold displacement energy distributions, providing a reliable description of atomic-scale collision processes. Molecular dynamics simulations of 5 keV cascades predict enhanced peak defect production and recombination relative to a widely used empirical potential, indicating different cascade evolution. By explicitly varying oxygen deficiency, we show that total defect production depends only weakly on stoichiometry, offering insight into the robustness of radiation damage processes in oxygen-deficient YBCO. Finally, fusion-relevant 300 keV cascade simulations reveal amorphous regions with dimensions comparable to the superconducting coherence length, consistent with electron microscopy observations of neutron-irradiated HTS tapes. These results establish machine-learned interatomic potentials as efficient and predictive tools for investigating radiation damage in YBCO across relevant compositions and irradiation conditions.
Superconductivity (cond-mat.supr-con)
Inverted-Mode Scanning Tunneling Microscopy for Atomically Precise Fabrication
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Eduardo Barrera, Bheeshmon Thanabalasingam, Rafik Addou, Damian Allis, Aly Asani, Jeremy Barton, Tomass Bernots, Brandon Blue, Adam Bottomley, Doreen Cheng, Byoung Choi, Megan Cowie, Chris Deimert, Michael Drew, Mathieu Durand, Tyler Enright, Robert A. Freitas Jr., Alan Godfrey, Ryan Groome, Si Yue Guo, Sheldon Haird, Aru Hill, Taleana Huff, Christian Imperiale, Alex Inayeh, Jerry Jeyachandra, Mark Jobes, Matthew Kennedy, Robert J. Kirby, Mykhaylo Krykunov, Sam Lilak, Hadiya Ma, Adam Maahs, Cameron J. Mackie, Oliver MacLean, Michael Marshall, Terry McCallum, Ralph C. Merkle, Mathieu Morin, Jonathan Myall, Alexei Ofitserov, Sheena Ou, Ryan Plumadore, Adam Powell, Max Prokopenko, Henry Rodriguez, Sam Rohe, Luis Sandoval, Marc Savoie, Khalil Sayed-Akhmad, Ben Scheffel, Tait Takatani, D. Alexander Therien, Finley Van Barr, Dusan Vobornik, Janice Wong, Reid Wotton, Ryan Yamachika, Cristina Yu, Marco Taucer
Scanning Tunneling Microscopy (STM) enables fabrication of atomically precise structures with unique properties and growing technological potential. However, reproducible manipulation of covalently bonded atoms requires control over the atomic configuration of both sample and probe - a longstanding challenge in STM. Here, we introduce inverted-mode STM, an approach that enables mechanically controlled chemical reactions for atomically precise fabrication. Tailored molecules on a Si(100) surface image the probe apex, and the usual challenge of understanding the probe structure is effectively solved. The molecules can also react with the probe, with the two sides of the tunnel junction acting as reagents positioned with sub-angstrom precision. This allows abstraction or donation of atoms from or to the probe apex. We demonstrate this by using a novel alkynyl-terminated molecule to reproducibly abstract hydrogen atoms from the probe. The approach is expected to extend to other elements and moieties, opening a new avenue for scalable atomically precise fabrication.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Wafer-Scale Integration of Piezo- and Ferroelectric Al0.64Sc0.36N Thin Films by Reactive Sputtering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Sanjay Nayak, Venkata Raveendra Nallagatla, Ravindra Singh Bisht, Dmytro Solonenko, Demian Henzen, Washim Reza Ali, Carla Maria Lazzari, Robert JW Frost, Andrea Serafini, Davide Codegoni, Amalia Balsamo, Rossana Scaldaferri, Elaheh Allahyari, Anirban Ghosh, Martin Kratzer, Andrea Picco, Sonia Costantini, Andrea Rusconi, Mohssen Moridi, Humberto Campanella, Marco Deluca, Annalisa De Pastina
Large-area deposition of Aluminium-Scandium-Nitride (Al1-xScxN) thin films with higher Sc content (x) remains challenging due to issues such as abnormal orientation growth, stress control, and the undesired crystal phase. These anomalies across the wafer hinder the development of high scandium-content AlScN films, which are critical for microelectromechanical systems applications. In this study, we report the sputter deposition of Al0.64Sc0.36N thin films from a 300 mm Al0.64Sc0.36 alloy target on 200 mm Si(100) wafers, achieving an exceptionally high deposition rate of 8.7 {\mu}m/h with less than 1% AOGs and controllable stress tuning. Comprehensive microstructural and electrical characterizations confirm the superior growth of high-quality Al0.64Sc0.36N films with exceptional wafer-average piezoelectric coefficients (d33,f =15.62 pm/V and e31,f = -2.9 C/m2) owing to low point defects density and grain mosaicity. This was accomplished through the implementation of an optimized seed layer and a refined electrode integration strategy, along with optimal process conditions. The wafer yield and device failure rates are analysed and correlated with the average stress of the films and their stress profiles along the diameter. The resulting films show excellent uniformity in structural, compositional, and piezoelectric properties across the entire 200 mm wafer, underscoring their strong potential for next-generation MEMS applications.
Materials Science (cond-mat.mtrl-sci)
Connecting strain rate dependence of fcc metals to dislocation avalanche signatures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
M. Aissaoui, C. Kahloun, O.U. Salman, S. Queyreau
Strain rate sensitivity is a key feature of material deformation, whose importance is growing both because miniaturized components experience higher effective rates and because small scale simulations increasingly probe such conditions. As a dynamical characteristic, strain rate dependence is shown to be intimately connected to dislocation avalanches, which are a fundamental mechanism of dislocation dynamics. Using carefully designed, state of the art dislocation dynamics simulations in the intermediate range strain rate from 5 to 1000, we show that increasing strain rate promotes the activation of a growing number of stronger sites. The dislocation microstructure progressively rearranges into configurations with shorter segments. Dislocation avalanches become larger through the superposition of simultaneous events and because stronger obstacles are required to arrest them. As a result, the avalanche statistics are strongly affected by strain rate, with a reduced power law regime and an increasing power law exponent. Larger avalanches, in turn, lead to an enhanced dislocation storage rate. Contribution from collinear systems to avalanches and cross slip activity decreases, altering the fraction of screw dislocations and the resulting microstructure. These results provide an original mesoscopic picture of rate sensitivity in this strain rate range and offer a mechanistic interpretation of existing observations and findings from experiments and simulations.
Materials Science (cond-mat.mtrl-sci)
Bridging Finite Element and Molecular Dynamics for Non-Fourier Thermal Transport Near Nanoscale Hot Spot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Nanoscale hot spots forming tens of nanometers beneath the gate in advanced FinFET and HEMT devices drive heat transport into a non-Fourier regime, challenging conventional (Fourier-based) finite-element (FEM) analyses and complicating future thermal-aware chip design. Molecular dynamics (MD) naturally captures ballistic transport and phonon nonequilibrium, but has not been applied to hot-spot problems due to computational cost. Here, we perform the first MD simulations of hot-spot heat transfer across ballistic-diffusive regimes and benchmark them against FEM. We find that FEM using bulk thermal conductivity $ \kappa_0$ significantly underestimates hot-spot temperature, even when the channel thickness is ~10 times the phonon mean free path, indicating persistent non-Fourier effects. We introduce a size-dependent “best” conductivity, $ \kappa_{\mathrm{best}}$ , using which FEM can reproduce MD hot-spot temperatures with high fidelity. We further decompose the MD-extracted thermal resistance into: (i) diffusive spreading, (ii) cross-plane ballistic, (iii) heat-carrier selective heating, and (iv) residual 3D ballistic-spreading resistances, and quantify each contribution. The resulting framework offers a practical route to embed non-Fourier physics into FEM for hot-spot prediction, reliability assessment, and thermally aware design of next-generation transistors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 7 figures
Proximity effect in SSH -superconductor junction
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
I. A. Belkovich, A. A. Radkevich
A model of microscopic interaction between a superconductor and a one-dimensional topological insulator, an SSH chain, is considered. Using the functional integration method, the effective action of the interaction between a superconductor and a topological insulator is obtained. We obtain corrections to the quasiparticle excitation spectrum of the SSH chain due to tunneling in various limits and discuss the influence of phase fluctuations. We find that for bulk superconductors, the states of the chain are stable for energies lying inside the superconducting gap while in lower-dimensional superconductors phase fluctuations yield finite temperature-dependent lifetimes even inside the gap. We also discuss whether these results can be reproduced within a simple phenomenological approach.
Superconductivity (cond-mat.supr-con)
Detection of a Rényi Index Dependent Transition in Entanglement Entropy Scaling
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Hatem Barghathi, Adrian Del Maestro
The scaling of entanglement with subsystem size encodes key information about phases and criticality, but the von Neumann entropy is costly to access in experiments and simulations, often requiring full state tomography. The second Rényi entropy is readily measured using two-copy protocols and is often used as a proxy for the von Neumann entanglement entropy, where it is assumed to track its asymptotic scaling. However, Sugino and Korepiny (Int. J. Mod. Phys. B 32, 1850306 (2018)) revealed that in the ground state of some spin models, the scaling of the von Neumann and second Rényi entropies varies from power law to logarithmic scaling as a function of the Rényi index. By constructing a number-conserving many-body state with only two local degrees of freedom, we obtain a Rényi-index-dependent change in the leading entanglement scaling: the second Rényi entropy remains logarithmic while the von Neumann entropy is parametrically larger. We then introduce a symmetry-aware lower bound on the von Neumann entropy built from charge-resolved second Rényi entropies and the subsystem charge distribution. Comparing this bound to the total second Rényi entropy provides a practical diagnostic for anomalous entanglement scaling from experimentally accessible data.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 5 figures. For associated data and code repository see: this https URL
Higher-order response theory in stochastic thermodynamics and optimal control
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Samuel. H. DAmbrosia, Adrianne Zhong, Michael R. DeWeese
Linear response theory has found many applications in statistical physics. One of these is to compute minimal-work protocols that drive nonequilibrium systems between different thermodynamic states, which are useful for designing engineered nanoscale systems and understanding biomolecular machines. We compare and explore the relationships between linear-response-based approximations used to study optimal protocols in different driving regimes by showing that they arise as controlled truncations of a general causal response (Volterra) expansion. We then construct higher-order response terms and discuss the drawbacks and utility of their inclusion. We illustrate our results for an overdamped particle in a harmonic trap, ultimately showing that the inclusion of higher-order response in calculating optimal protocols provides marginal improvement in effectiveness despite incurring a significant computational expense, while introducing the possibility of predicting arbitrarily low and unphysical negative excess work.
Statistical Mechanics (cond-mat.stat-mech)
17 pages, 4 figures
From Berry curvature to quantum metric: a new era of quantum geometry metrology for Bloch electrons in solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
For decades, ``geometry” in band theory has largely meant Berry phase and Berry curvature-quantities that reshape semiclassical dynamics and underpin modern topological matter. Yet the full geometric content of a Bloch band is richer and encoded in the quantum geometric tensor (QGT), whose imaginary part is the Berry curvature and whose real part is the quantum metric. Here, we briefly review the recent progress in direct experimental access to the QGT in real crystalline solids using the polarization- and spin-resolved angle-resolved photoemission spectroscopy (ARPES). The extraction of the QGT in momentum space was successfully addressed by two different approaches: One is by introducing quasi-QGT that faithfully represents the QGT and is directly measurable by ARPES. The other is through pseudospin tomography in a material with simple low energy band structure, which successfully retrieved all matrix components of the quantum metric. We discuss the physical meaning of these two recent progresses, their implication/limitation, and open directions.
Materials Science (cond-mat.mtrl-sci)
An invited perspective article submitted to Chinese Physics Letters
Higgs and Nambu-Goldstone modes in a spin-1 \textit{XY} model with long-range interactions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
Daiki Kawasaki, Ippei Danshita
We theoretically study the collective excitations in a spin-1 $ XY$ model with a quadratic Zeeman term and a long-range interaction that decays algebraically with the distance. Using the quantum-field theory based on the finite-temperature Green’s function formalism, we analyze properties of the Nambu-Goldstone (NG) and Higgs modes in order to analytically evaluate the damping rate of the Higgs mode in the $ XY$ ferromagnetic ordered phase near the quantum phase transition to the disordered phase. When the power of the algebraic decay is 3 as in the case of dipole-dipole interactions in Rydberg-atom systems, we show that at two dimensions the excitation energy of the Higgs mode exhibits a linear dispersion whereas the dispersion of the NG mode becomes proportional to the square root of the momentum. We find that the damping of the Higgs mode is significantly suppressed by the long-range interaction. We also propose how to excite and probe the Higgs mode in Rydberg-atom experiments.
Quantum Gases (cond-mat.quant-gas)
10 pages, 4 figures
Dynamics of Interfacial Diffusion Control in Amphiphilic Lipid-Coated Micro-Particles for Stochastic Release Systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
The release of hydrophilic solutes from micron scale particulate formulations can be understood as an interfacial transport problem in which diffusion across a heterogeneous amphiphilic coating competes with dissolution and convective removal in the surrounding medium. Here we reinterpret a glycerin fatty acid ester (GFAE) coated thiamine (vitamin B1) micro particle formulation as a condensed matter system: a soft matter core shell geometry whose effective permeability is set by the nanoscale organization of amphiphilic lipids at the interface. Using in vivo time course serum measurements in mice as a proxy for a stochastic sink, we compare the coated formulation (UTEV) with a composition matched uncoated comparator (UMFG). Early time systemic appearance is similar, whereas late time levels are enhanced for the coated particles, implying a reduced effective interfacial diffusivity and a broadened release-time distribution. We discuss the results in terms of diffusion barrier physics, heterogeneous interfacial energetics, and coarse grained transport models that map microstructural coating parameters to macroscopic persistence (AUC).
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
8 pages, 5 figures, 2 tables
Matter with apparent and hidden spin physics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Jia-Xin Xiong, Xiuwen Zhang, Lin-Ding Yuan, Alex Zunger
Materials with interesting physical properties are often designed based on our understanding of the target physical effects. The physical properties can be either explicitly observed (“apparent”) or concealed by the perceived symmetry (“hidden”) but still exist. Both are enabled by specific symmetries and induced by certain physical interactions. Using the underlying approach of condensed matter theory of real materials (rather than schematic model Hamiltonians), we discuss apparent and hidden physics in real materials focusing on the properties of spin splitting and spin polarization. Depending on the enabling symmetries and underlying physical interactions, we classify spin effects into four categories with each having two subtypes; representative materials are pointed out. We then discuss the electric tunability and switch of apparent and hidden spin splitting and polarization in antiferromagnets. Finally, we extend “hidden effects” to views that are farsighted in the sense of resolving the correct atomistic and reciprocal symmetry and replaced by the incorrect higher symmetry. This framework could guide and enable systematic discovery of such intriguing effects.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
33pages, 6 figures, 1 table
Origins of spontaneous magnetic fields in Sr$_2$RuO$_4$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Yongwei Li, Rustem Khasanov, Stephen P. Cottrell, Naoki Kikugawa, Yoshiteru Maeno, Binru Zhao, Jie Ma, Vadim Grinenko
The nature of the broken time reversal symmetry (BTRS) state in Sr$ _2$ RuO$ _4$ remains elusive, and its relation to superconductivity remains controversial. There are various universal predictions for the BTRS state when it is associated with a multicomponent superconducting order parameter. In particular, in the BTRS superconducting state, spontaneous fields appear around crystalline defects, impurities, superconducting domain walls and sample surfaces. However, this phenomenon has not yet been experimentally demonstrated for any BTRS superconductor. Here, we aimed to verify these predictions for Sr$ _2$ RuO$ _4$ by performing muon spin relaxation ($ \mu$ SR) measurements on Sr$ _{2-y}$ La$ _{y}$ RuO$ _4$ single crystals at ambient pressure and stoichiometric Sr$ _2$ RuO$ _4$ under hydrostatic pressure. The study allowed us to conclude that spontaneous fields in the BTRS superconducting state of Sr$ _2$ RuO$ 4$ appear around non-magnetic inhomogeneities and, at the same time, decrease with the suppression of $ T{\rm c}$ . The observed behaviour is consistent with the prediction for multicomponent BTRS superconductivity in Sr$ _2$ RuO$ _4$ . The results of the work are relevant to understanding BTRS superconductivity in general, as they demonstrate, for the first time, the relationship among the superconducting order parameter, the BTRS transition, and crystal-structure inhomogeneities.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Open quantum theory of magnetoresistance in mesoscopic magnetic materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Xian-Peng Zhang, Xiangrong Wang, Yugui Yao
Magnetoresistance (MR) in magnetic materials arises from spin-exchange coupling between local moments and itinerant electrons, representing a challenging many-body open-quantum problem. Here we develop a comprehensive microscopic theory of MR within an open-quantum-system framework by solving the Liouville-von Neumann equation for a hybrid system of free electrons and local moments using the time-convolutionless projection operator method. Our approach reveals both ferromagnetic and antiferromagnetic MR as consequences of temperature- and field-dependent spin decoherence, encompassing spin relaxation and dephasing. In particular, the resistance associated with spin decoherence is governed by the order parameters of magnetic materials, such as the magnetization in ferromagnets and the Néel vector in antiferromagnets. This theory deepens the fundamental understanding of MR and offers guidance for interpreting and designing experiments on magnetic materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:2406.13932
Dynamic Phase Transitions in Periodically Driving 1D Ising Model
New Submission | Other Condensed Matter (cond-mat.other) | 2026-01-01 20:00 EST
Yuanyuan Cheng, Yuxia Zhang, Tianhui Qiu, Peipei Xin, Bao-Ming Xu
This work investigates dynamical quantum phase transitions (DQPTs) in a one-dimensional Ising model subjected to a periodically modulated transverse field. In contrast to sudden quenches, we demonstrate that DQPTs can be induced in two distinct ways. First, when the system remains within a given phase–ferromagnetic (FM) or paramagnetic (PM), a resonant periodic drive can trigger a DQPT when its frequency matches the energy-level transition of the system. The timescale for the transition is governed by the perturbation strength $ \lambda’$ , the critical mode $ k_c$ , and its energy gap $ \Delta_{k_c}$ , following the scaling relation $ \tau \propto \sin^{-1}k_c \Delta_{k_c}\lambda’^{-1}$ . Second, for drives across the critical point between the FM and PM phases, low frequencies can always induce DQPTs, regardless of resonance. This behavior stems from the degeneracy of the energy-level at the critical point, which ensures that any drive with a frequency lower than the system’s intrinsic transition frequency will inevitably excite the system. However, in the high-frequency regime, such excitation will be strongly suppressed, thereby inhibiting the occurrence of DQPTs. This study provides deeper insight into the nonequilibrium dynamics of quantum spin chains.
Other Condensed Matter (cond-mat.other)
8 pages, 5 figures
Vapor-solid-solid growth of single-walled carbon nanotubes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Single-walled carbon nanotubes are one-dimensional $ sp^2$ carbon materials whose electronic and optical properties are governed by their chirality. Catalytic chemical vapor deposition often uses transition-metal nanoparticles that liquefy at elevated temperature, and vapor-liquid-solid growth is commonly associated with broad chirality distributions. Improved selectivity has been reported for high-melting-point catalysts that remain solid, suggesting vapor-solid-solid growth, but the underlying kinetics and interface structure remain poorly resolved. The mechanisms that control carbon delivery and determine edge structure on solid catalysts are therefore unclear. Here it is shown, using microsecond-scale molecular dynamics driven by a neuroevolution machine-learning interatomic potential, that rhenium nanoparticles remain solid above 1123.15 K and that surface carbon at 5.0 to 6.0 nm$ ^{-2}$ does not appreciably depress melting. Carbon transport is dominated by facet-dependent surface diffusion, bounding sustainable supply on a 2.0 nm particle to $ \sim 44$ carbon atoms per $ \mu$ s on the slow $ (10\bar{1}1)$ facet. Consistently, growth at 50 carbon atoms per $ \mu$ s occurs only within a narrow window: multiple nucleation or encapsulation is promoted at 1300 K, tubular elongation is obtained at 1400 K, and low-curvature graphitic structures dominate at 1500 K and above. Non-hexagonal rings persist over 12 $ \mu$ s, while zigzag-rich, strongly Klein-decorated edges are stabilized and deviate from configurational-entropy expectations for liquid catalysts. These results place catalyst reconstruction by surface carbon adsorption, facet-controlled diffusion, and crystalline interfacial thermodynamics at the center of vapor-solid-solid growth control, motivating experimental tuning of temperature and feedstock partial pressure to balance diffusion-limited supply against encapsulation pathways.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantum Computing Inspired Approach for Self-Avoiding Walk (SAWs): 2D lattice and 3D lattice SAWs for single chain enumeration
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Hemant Mishra, Shubham Singh, Rajeev Singh, Amit Raj Singh
We investigate the application of quantum computing algorithms to enhance the efficiency of enumerating self-avoiding walks (SAWs), utilizing quantum properties such as superposition and interference. A Quantum Amplitude Estimation (QAE)-based algorithm is developed to enumerate SAWs on both 2D and 3D lattices. In case of 2D square lattice, SAWs up to N=71 steps are successfully enumerated within 26.9 minutes - significantly improving upon the classical algorithm, which required approximately 231 hours(Jensen et al., 2012, J. Phys. A: Math. Theor. 45, 115202). The algorithm is further extended to 3D cubic lattices, where SAWs up to N=40 steps are enumerated in 13.06 minutes, compared to the classical result of N=36 in 250 hours (Schram et al., 2011, J. Stat. Mech. P06019). These results demonstrate a substantial reduction in computational time, highlighting the potential of quantum computing for combinatorial enumeration problems.
Statistical Mechanics (cond-mat.stat-mech)
13pages, 8 figures
Disentangle Intertwined Interactions in Correlated Charge Density Wave with Magnetic Impurities
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
J. W. Park, H. Kim, H. W. Yeom
Magnetic impurities in strongly correlated electronic systems serve as sensitive probes to a wide range of many-body quantum phenomena. Broken symmetries in such a system can lead to inequivalent lattice sites, and magnetic impurities may interact selectively with particular orbitals or sublattices. However, the microscopic mechanisms behind such site-specific interactions have been poorly understood. Here, we explore the behavior of individual Fe adatoms on a cluster-Mott charge-density-wave (CDW) system of 1T-TaS2 utilizing scanning tunneling microscopy/spectroscopy (STM/STS) and density functional theory (DFT). Our measurements uncover pronounced site-dependent electronic states of CDW clusters with Fe adatoms, indicating distinct local coupling to cluster-Mott states. DFT calculations identify three distinct types of interactions; hybridization with localized correlated electrons, distorting the CDW cluster, and charge transfer. In particular, the hybridization of Fe 3d and half-filled Ta 5dz2 orbitals suppresses the Mott insulating state for an adatom at the center of a CDW cluster. While the results underscore a crucial role of the direct orbital hybridization and the limitation of the prevailing single-site Kondo impurity model, they suggest the possibility of controlling entangled interactions separately in a cluster Mott insulator.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
22 pages, 5 figures
Observing unconventional superconductivity via kinetic inductance in Weyl semimetal MoTe$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Mary Kreidel, Julian Ingham, Xuanjing Chu, Jesse Balgley, Ted S. Chung, Abhinandan Antony, Nishchhal Verma, Luke N. Holtzman, Katayun Barmak, Raquel Queiroz, James Hone, Robert M. Westervelt, Kin Chung Fong
Identifying the pairing symmetry of unconventional superconductors plays an essential role in the ongoing quest to understand correlated electronic matter. A long-standing approach is to study the temperature dependence of the London penetration depth $ \lambda$ for evidence of nodal points where the superconducting gap vanishes. However, experimental reports can be ambiguous due to the requisite low-temperature resolution, and the similarity in signatures of nodal quasiparticles and impurity states. Here we study the pairing symmetry of Weyl semimetal $ T_d$ -MoTe$ _2$ , where previous measurements of $ \lambda$ have yielded conflicting results. We utilize a novel technique based on a microwave resontor to measure the kinetic inductance of MoTe$ _2$ , which is directly related to $ \lambda$ . The high precision of this technique allows us to observe power-law temperature dependence of $ \lambda$ , and to measure the anomalous nonlinear Meissner effect – the current dependence of $ \lambda$ arising from nodal quasiparticles. Together, these measurements provide smoking gun signatures of nodal superconductivity.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
8+6 pages, 4+5 figures
Modulation of quantum geometry and its coupling to pseudo-electric field by dynamic strain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Surat Layek, Mahesh A. Hingankar, Ayshi Mukherjee, Atasi Chakraborty, Digambar A. Jangade, Anil Kumar, L. D. Varma Sangani, Amit Basu, R Bhuvaneswari, Kenji Watanabe, Takashi Taniguchi, Amit Agarwal, Umesh V. Waghmare, Mandar M. Deshmukh
Two-dimensional materials are a fertile ground for exploring quantum geometric phenomena, with Berry curvature and its first moment, the Berry curvature dipole, playing a central role in their electronic response. These geometric properties influence electronic transport and result in the anomalous and nonlinear Hall effects, and are typically controlled using static electric fields or strain. However, the possibility of modulating quantum geometric quantities in real-time remains unexplored. Here, we demonstrate the dynamic modulation of Berry curvature and its moments, as well as the generation of a pseudo-electric field using time-dependent strain. By placing heterostructures on a membrane, we introduce oscillatory strain together with an in-plane AC electric field and measure Hall signals that are modulated at linear combinations of the frequencies of strain and electric field. Our measurements reveal modulation of Berry curvature and its first moment. Notably, we provide direct experimental evidence of pseudo-electric field that results in an unusual dynamic strain-induced Hall response. This approach opens up a new pathway for controlling quantum geometry on demand, moving beyond conventional static perturbations. The pseudo-electric field provides a framework for external electric field-free anomalous Hall response and opens new avenues for probing the topological properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
26 pages, 5 figures, 5 extended figures
Fragile Topological Phases and Topological Order of 2D Crystalline Chern Insulators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
We apply methods of equivariant homotopy theory, which may not previously have found due attention in condensed matter physics, to classify first the fragile/unstable topological phases of 2D crystalline Chern insulator materials, and second the possible topological order of their fractional cousins. We highlight that the phases are given by the equivariant 2-Cohomotopy of the Brillouin torus of crystal momenta (with respect to wallpaper point group actions) – which, despite the attention devoted to crystalline Chern insulators, seems not to have been considered before. Arguing then that any topological order must be reflected in the adiabatic monodromy of gapped quantum ground states over the covariantized space of these band topologies, we compute the latter in examples where this group is non-abelian, showing that any potential FQAH anyons must be localized in momentum space. We close with an outlook on the relevance for the search for topological quantum computing hardware. Mathematical details are spelled out in a supplement.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Algebraic Topology (math.AT), Quantum Physics (quant-ph)
15 pages, 8 figures
Phase transitions in time complexity of Brownian circuits
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Brownian circuits implement computation through stochastic transitions driven by thermal fluctuations. While the energetic costs of such fluctuation-driven computation have been extensively studied within stochastic thermodynamics, much less is known about its computational complexity, in particular how computation time scales with circuit size. Here, the computation time of explicitly designed Brownian circuits is investigated numerically via the first-passage time to a completed state. For arithmetic circuits such as adders, varying the forward transition rate induces a sharp change in the scaling behavior of the mean computation time, from linear to exponential in circuit size. This change can be interpreted as an easy-hard transition in computational time complexity. The transition suggests that, for meaningful computational tasks, achieving efficient polynomial-time computation generically requires a finite forward bias, corresponding to a nonzero energy input. As a counterexample, it is shown that arbitrary logical operations can be reduced to an effectively one-dimensional stochastic process, for which the zero-bias limit lines within the computationally efficient (easy) regime. However, realizing such a one-dimensional normal form unavoidably leads to an exponential increase in circuit size. These results reveal a fundamental trade-off between computation time, circuit size, and energy input in Brownian circuits, and demonstrate that phase transitions in time complexity provide a natural framework for characterizing the cost of fluctuation-driven computation.
Statistical Mechanics (cond-mat.stat-mech)
The disordered Su-Schrieffer-Heeger model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-01-01 20:00 EST
Quantum topology categorizes physical systems in integer invariants, which are robust to some deformations and certain types of disorder. A prime example is the Su-Schrieffer-Heeger (SSH) model, which has two distinct topological phases, the trivial phase with no edge states and the non-trivial phase with zero-energy edge states. The energy dispersion of the SSH model is dominated by a gap around zero energy, which suppresses the transmission. This exponential suppression of the transmission with system length is determined by the Lyapounov exponent. Here we find an analytical expression of the Lyapounov as a function of energy in the presence of both diagonal and off-diagonal disorder. We obtain this result by finding a recurrence relation for the local density, which can be averaged over different disorder configurations. There is excellent agreement between our analytical expression and the numerical results over a wide range of disorder strengths and disorder types. The real space winding number is evaluated as a function of off-diagonal and on-site disorder for possible applications of quantum topology.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
Supercurrent from the imaginary part of the Andreev levels in non-Hermitian Josephson junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Roberto Capecelatro, Marco Marciani, Gabriele Campagnano, Roberta Citro, Procolo Lucignano
We investigate the electronic transport properties of a superconductor-quantum dot-superconductor Josephson junction coupled to a ferromagnetic metal reservoir in the presence of an external magnetic field. The device is described by an effective non-Hermitian Hamiltonian, whose complex eigenvalues encode the energy (real part) and the broadening (imaginary part) of the Andreev quasi-bound states. When extending the Andreev current formula to the non-Hermitian case, a novel contribution arises that is proportional to the phase derivative of the levels broadening. This term becomes particularly relevant in the presence of exceptional points (EPs) in the spectrum, but its experimental detection is not straightforward. We identify optimal Andreev spectrum configurations where this novel current contribution can be clearly highlighted, and we outline an experimental protocol for its detection. We point out that the phase dependence in the levels imaginary part originates from the breaking of a time-reversal-like symmetry. In particular, spectral configurations in the broken phase of the symmetry and without EPs can be obtained, where this novel contribution can be easily resolved. The proposed protocol would allow to probe for the first time a fingerprint of non-Hermiticity in open junctions that is not strictly related to the presence of EPs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Review, main text 10 pages, appendices 6 pages, 10 figures. Comments are welcome
A Quantum Framework for Negative Magnetoresistance in Multi-Weyl Semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Arka Ghosh, Sushmita Saha, Alestin Mawrie
We develop a fully quantum-mechanical theory of negative magnetoresistance in multi-Weyl semimetals in the $ {\bf E}\parallel{\bf B}$ configuration, where the chiral anomaly is activated. The magnetotransport response is governed by Landau quantization and the emergence of multiple chiral Landau levels associated with higher-order Weyl nodes. These anomaly-active modes have unidirectional dispersion fixed by the node’s monopole charge and dominate charge transport. As the magnetic field increases, individual chiral branches successively cross the Fermi energy, producing discrete slope changes in the longitudinal conductivity and a step-like negative magnetoresistance. This quantized evolution provides a direct experimental signature of multi-Weyl topology. Bulk Landau levels contribute only at very low fields due to strong disorder scattering and do not affect the anomaly-driven regime. Our results establish a unified, fully quantum-mechanical framework in which negative magnetoresistance arises from the discrete Landau-quantized spectrum and microscopic impurity scattering, beyond semiclassical anomaly descriptions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 4 figures
Essential Principles and Practices in X-ray Photoelectron Spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
X-ray Photoelectron Spectroscopy (XPS) is a widely utilized technique for chemical analysis of solid surfaces, sensitive to the chemical environment of atoms via core-level binding energy shifts. While modern instruments allow obtaining the experimental data with ease, their evaluation and interpretation is challenging to newcomers to the field as a profound knowledge of the method is required for a correct analysis. Here we present a concise yet comprehensive introduction to the fundamental principles and methodologies of XPS, covering photoemission processes, chemical shifts, charge referencing, peak fitting, and quantification strategies. This overview aims to bridge the gap between data collection and reliable analysis, providing essential knowledge for correct interpretation. By clarifying key concepts and common practices, this work supports improved accuracy in surface chemical characterization using XPS.
Materials Science (cond-mat.mtrl-sci)
Intriguing Magnetocaloric Effect in 6H-perovskite Ba3RRu2O9 (R=Ho, Gd, Tb, Nd) with Strong 4d-4f Correlations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Mohit Kumar, Sayan Ghosh, Gourab Roy, Ekta Kushwaha, Vincent Caignaert, Wilfrid Prellier, Subham Majumdar, Vincent Hardy, Tathamay Basu
Here we demonstrate the magnetocaloric effect (MCE) of a 4d-4f correlated system, namely Ba3RRu2O9 (R= Ho, Gd, Tb, Nd). The compound Ba3HoRu2O9 antiferromagnetically orders at 50 K where both the Ho and Ru-moments order, followed by another phase transition ~ 10 K. Whereas, the compound Ba3GdRu2O9 and Ba3TbRu2O9 orders at 14.5 and 10.5 K respectively, where the ordering of both R and Ru moments are speculated. Our results reveal robust MCE around low-T magnetic phase transition for all the heavy rare-earth members (Ho, Gd, Tb) in this family. The heavy rare-earth members exhibit an intriguing MCE behavior switching from conventional to non-conventional MCE. Interestingly, the light R-member, Ba3NdRu2O9, orders ferromagnetically below 24 K where Nd-moments order, followed by Ru-ordering below 18 K, exhibits a positive MCE below and above FM-ordering. The compelling MCE are attributed to temperature dependent complex spin-reorientations for different R-members and anisotropy.
Strongly Correlated Electrons (cond-mat.str-el)
Mobility-induced phase separation in a binary mixture of active Brownian particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
D. Jiménez-Flores, A. Rodríguez-Rivas, J. M. Romero-Enrique
In this paper, we report a Brownian dynamics simulation of the mobility-induced phase separation which occurs in a two-dimensional binary mixture of active soft Brownian particles, whose interactions are modeled by non-additive Weeks-Chandler-Andersen potentials inspired in Lennard-Jones potentials used for glass-forming passive mixtures. The analysis of structural properties, such as the radial distribution functions and the hexatic order parameter, shows that the high-density coexisting state in the binary case is spatially disordered, unlike the solid-like state observed for the monocomponent system. Characterization of the mean-square displacement of the active particles shows that both the low- and high-density coexisting states have diffusive behavior for long times. Thus, the high-density coexisting states are liquid-like in the binary cases. Moreover, diffusive behavior is also observed in the high-density solid-like state for the monocomponent system, which is driven by the presence of active topological defects.
Soft Condensed Matter (cond-mat.soft)
13 pages, 8 figures
Temperature dependence of the spontaneous magnetization of Ni2MnGa and other ferromagnets. The superellipse equation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
The temperature dependence of the spontaneous magnetization of Ni2MnGa and other ferromagnets can be described in reduced coordinates by the superellipse equation using a single dimensionless parameter. This critical exponent parameter equals 2.4 for Ni2MnGa, 2.7 for nickel and cobalt, and 3.0 for iron. Because reduced magnetization and reduced temperature enter the equation symmetrically, the Ms(T) dependence can be measured experimentally only in the low-temperature range, from 0 to 0.5TC. The magnetization curve from 0.5TC to TC can then be obtained by interchanging reduced magnetization and temperature in the superellipse equation. In this way, the experimentally challenging task of measuring spontaneous magnetization near Tc is avoided, as the behavior near Tc is effectively determined from measurements performed near T = 0.
Materials Science (cond-mat.mtrl-sci)
6 pages, 5 figures
Novel exact solutions of the Duffing equation: stability analysis and application to real non-linear deformation tests
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-01-01 20:00 EST
A.D. Berezner, V.A. Fedorov, N.S. Perov, G.V. Grigoriev
In this study, novel exact solutions of the Duffing equation with their phase portraits have been proposed and reasoned. It is shown that phase trajectories are initially elliptical and become distorted in the unstable area within the growth of the variable parameter. Instability criteria of identified solutions have been determined together with the Fourier series transformation up to the first and high harmonics in a sense of the physical interpretation. An explicit form for the differential operator, corresponding to considered functions, has been derived with evaluation of its main functional spectrum. Non-isothermal creep tests of different materials were completely described using the Duffing equation via noted solutions up to the fracture as processes with personal deformation response. We successfully examined a relationship between the thermal and magnetic properties of the ferromagnetic amorphous alloy under its non-linear deformation, using the critical exponents. With a high linear correlation between our model and experiments, behaviour of organic and metallic systems is well predicted at the same thermo-mechanical testing conditions on the mesoscale.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
preprint article, 29 pages, 21 figures
Quasiparticle Dynamics in the 4d-4f Ising-like Double Perovskite Ba2DyRuO6 Probed by Neutron Scattering and Machine-Learning Framework
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Gourab Roy, Ekta Kushwaha, Mohit Kumar, Sayan Ghosh, Fabio Orlandi, Duc Le, Matthew B. Stone, Jhuma Sannigrahi, Devashibhai T. Adroja, Tathamay Basu
Double perovskites containing 4d–4f interactions provide a platform to study complex magnetic phenomena in correlated systems. Here, we investigate the magnetic ground state and quasiparticle excitations of the fascinating double perovskite system, Ba$ _2$ DyRuO$ 6$ , through Time of flight (TOF) neutron diffraction (TOF), inelastic neutron scattering (INS), and theoretical modelling. The compound Ba$ 2$ DyRuO$ 6$ is reported to exhibit a single magnetic transition, in sharp contrast to most of the other rare-earth (R) members in this family, A$ 2$ RRuO$ 6$ (A = Ca/Sr/Ba), which typically show magnetic ordering of the Ru ions, followed by R-ion ordering. Our neutron diffraction results confirm that long-range antiferromagnetic order emerges at $ T\mathrm{N} \approx 47$ ~K, primarily driven by 4d–4f Ru$ ^{5+}$ –Dy$ ^{3+}$ exchange interactions, where both Dy and Ru moments start to order simultaneously. The ordered ground state is a collinear antiferromagnet with Ising character, carrying ordered moments of $ \mu{\mathrm{Ru}} = 1.6(1)~\mu\mathrm{B}$ and $ \mu{\mathrm{Dy}} = 5.1(1)~\mu\mathrm{B}$ at 1.5K. Low-temperature INS reveals well-defined magnon excitations below 10meV. SpinW modelling of the INS spectra evidences complex exchange interactions and the presence of magnetic anisotropy, which governs the Ising ground state and accounts for the observed magnon spectrum. Combined INS and Raman spectroscopy reveal crystal-electric-field (CEF) excitations of Dy$ ^{3+}$ at 46.5 and 71.8~meV in the paramagnetic region. The observed CEF levels are reproduced by point-charge calculations consistent with the $ O_h$ symmetry of Dy$ ^{3+}$ . A complementary machine-learning approach is used to analyse the phonon spectrum and compare with INS data. Together, these results clarify the origin of phonon and magnon excitations and their role in the ground-state magnetism of Ba$ _2$ DyRuO$ _6$ .
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Non-equilibrium pathways between cluster morphologies in active phase separation: necking, rupture and cavitation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
Liheng Yao, Michael E. Cates, Robert L. Jack
We investigate the dynamical pathways of a geometric phase transition in a two-dimensional active lattice gas undergoing motility-induced phase separation. The transition is between metastable morphologies of the liquid cluster: a system-spanning “slab” and a compact “droplet”. We generate trajectories of this transition in both directions using forward flux sampling. We find that the droplet-to-slab transition always follows a similar mechanism to its equilibrium counterpart, but the reverse (slab-to-droplet) transition depends on rare non-equilibrium fluctuations. At low Peclet numbers the equilibrium and non-equilibrium pathways compete, while at high Peclet numbers the equilibrium pathway is entirely suppressed, and the only allowed mechanism involves a large vapour bubble. We discuss the implications of these findings for active matter systems more generally.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
10 pages, 7 figures
Training for Transport and Localization in Quantum System
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Through periodic Training we can gradually buildup a reproducible responses in a disordered system where plasticity dominates over elasticity as is known in classical amorphous materials and soft matter 1, 6. Here we show that a similar concept can be extended to disordered quantum systems. Periodic electrical or mechanical driving of a disordered quantum-dot network can sculpt the effective Hamiltonian, producing either a low-energy transport valley that enhances exciton conduction, or a localized regime with many body memory like behavior. Our results establish training as a new paradigm for creating functional order in disordered quantum matter.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Active phase separation: role of attractive interactions from stalled particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
Dry active matter systems are well-known to exhibit Motility-Induced Phase Separation (MIPS). However, in wet active systems, attractive hydrodynamic interactions mediated by active particles stalled at a boundary can introduce complementary mechanisms for aggregation. In the work of Caciagli et al. (PRL 125, 068001, 2020), it was shown that the attractive hydrodynamic interactions due to active particles stalled at a boundary can be described in terms of an effective potential. In this paper, we present a model of active Brownian particles, where a fraction of active particles are stalled, and thus, mediate inter-particle interactions through the effective potential. Our investigation of the model reveals that a small fraction of stalled particles in the system allows for the formation of dynamical clusters at significantly lower densities than predicted by standard MIPS. We provide a comprehensive phase diagram in terms of weighted average cluster sizes that is mapped in the plane of the fraction of stalled particles ($ \alpha$ ) and the Peclet number. Our findings demonstrate that even a marginal value of $ \alpha$ is sufficient to drive phase separation at low global densities, bridging the gap between theoretical models and experimental observations of dilute active systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
4 Figures and 5 pages
Upscaling from ab initio atomistic simulations to electrode scale: The case of manganese hexacyanoferrate, a cathode material for Na-ion batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Yuan-Chi Yang, Eric Woillez, Quentin Jacquet, Ambroise van Roekeghem
We present a generalizable scale-bridging computational framework that enables predictive modeling of insertion-type electrode materials from atomistic to device scales. Applied to sodium manganese hexacyanoferrate, a promising cathode material for grid-scale sodium-ion batteries, our methodology employs an active-learning strategy to train a Moment Tensor Potential through iterative hybrid grand-canonical Monte Carlo–molecular dynamics sampling, robustly capturing configuration spaces at all sodiation levels. The resulting machine learning interatomic potential accurately reproduces experimental properties including volume expansion, operating voltage, and sodium concentration-dependent structural transformations, while revealing a four-order-of-magnitude difference in sodium diffusivity between the rhombohedral (sodium-rich) and tetragonal (sodium-poor) phases at 300 K. We directly compute all critical parameters – temperature- and concentration-dependent diffusivities, interfacial and strain energies, and complete free-energy landscapes – to feed them into pseudo-2D phase-field simulations that predict phase-boundary propagation and rate-dependent performances across electrode length scales. This multiscale workflow establishes a blueprint for rational computational design of next-generation insertion-type materials, such as battery electrode materials, demonstrating how atomistic insights can be systematically translated into continuum-scale predictions.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
24 pages, 14 figures
Time-Reversal Symmetry Breaking Superconducting State and Collective Modes in Kagome Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-01-01 20:00 EST
Xinloong Han, Jun Zhan, Jiangping Hu, Fu-chun Zhang, Xianxin Wu
We comprehensively study the unconventional pairing and collective modes in the multiband kagome superconductors AV$ _3$ Sb$ _5$ (A=$ \mathrm{K},\mathrm{Cs},\mathrm{Rb}$ ). By solving gap equations at zero temperature, we identify a transition from normal $ s++/s\pm$ -wave pairing to time-reversal symmetry (TRS) breaking pairing with a variation of inter-pocket interactions or density of states. This TRS breaking pairing originates from the superconducting phase frustration of different Fermi pockets and can account for experimental TRS breaking signal in kagome superconductors. Moreover, we investigate collective modes, including the Higgs, Leggett, and Bogoloubov-Anderson-Goldstone modes, arising from fluctuations of the amplitude, relative phase, and overall phase of the superconducting order parameters, respectively. Remarkably, due to the presence of multibands, one branch of the Leggett modes becomes nearly massless near the TRS breaking transition, providing a compelling smoking-gun signature of TRS-breaking superconductivity, in clear contrast to TRS-breaking charge orders. Our results elucidate the rich superconducting physics and its associated collective modes in kagome metals, and suggest feasible experimental detection of TRS breaking pairing.
Superconductivity (cond-mat.supr-con)
10 pages, 4 figures
SSCHA-based evolutionary crystal structure prediction at finite temperatures with account for quantum nuclear motion
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Accurate crystal structure prediction (CSP) at finite temperatures with quantum anharmonic effects remains challenging but very prominent in systems with lightweight atoms such as superconducting hydrides. In this work, we integrate machine-learned interatomic potentials (MLIPs) with the stochastic self-consistent harmonic approximation (SSCHA) to enable evolutionary CSP on the quantum anharmonic free-energy landscape. Using LaH$ _{10}$ at 150 GPa and 300 K as a test case, we compare two approaches for SSCHA-based CSP: using light-weight active-learning MLIPs (AL-MLIPs) trained on-the-fly from scratch, and foundation models or universal MLIPs (uMLIPs) from the Matbench project. We demonstrate that AL-MLIPs allow to correctly predict the experimentally known cubic Fm$ \bar{3}$ m phase as the most stable polymorph at 150 GPa but require corrections within the thermodynamic perturbation theory to get consistent results. The uMLIP Mattersim-5m allow to conduct SSCHA-based CSP without requiring per-structure training and even get correct structure ranking near the global minimum, though fine-tuning may be needed for higher accuracy. Our results show that including quantum anharmonicity simplifies the free-energy landscape and is essential for correct stability rankings, that is especially important for high-temperature phases that could be missed in classical 0 K CSP. The proposed approach extends the reach of CSP to systems where quantum nuclear motion and anharmonicity dominate.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Regularized universal topological local markers for Dirac systems
New Submission | Other Condensed Matter (cond-mat.other) | 2026-01-01 20:00 EST
Yulin Qin, Chang-An Li, Jian Li
Local markers provide an efficient and powerful characterization of topological features of many systems, especially when the translation symmetry is broken. Recently, a universal topological local marker applicable in different symmetry classes of topological systems is proposed. However, it suffers from irregular behaviors at the boundary and its connection to other topological indexes remains elusive. In this work, we construct regularized universal topological local markers that apply to Dirac systems by utilizing position operators that are compatible with periodic boundary conditions. The regularized local markers eliminate the obstructive boundary irregularities successfully, and give rise to the desired global topological invariants such as the Chern number consistently when integrated over all the lattice sites. Furthermore, the regularized form allows us to establish an explicit connection between the local markers and some other known topological indices in two dimensions. For instance, it turns out to be equivalent to the Bott index in classes A, D, and C, and equivalent to the spin Chern number in classes DIII and AII. We further examine the utility and stability of this new marker in disordered scenarios. We find that its variance shows peaks at the phase boundaries, which promotes it as a useful indicator for detecting disorder-induced topological phase transitions.
Other Condensed Matter (cond-mat.other), Disordered Systems and Neural Networks (cond-mat.dis-nn)
9 pages, 4 figures
Metallic solid-state hydrogen storage crystals achieved through chemical precompression under ambient conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Baiqiang Liu, Chenxi Wan, Rui Liu, Zhen Gong, Jia Fan, Zhigang Wang
Improving hydrogen storage density is essential for reducing the extreme conditions required in applications such as nuclear fusion. However, the recognition of metallic hydrogen as the “Holy Grail” of high-pressure science highlights the difficulty of high-density hydrogen aggregation. Here, we report a solid-state crystal H9@C20 formed by embedding hydrogen atoms into C20 fullerene cages and utilizing chemical precompression, which remains stable under ambient pressure and temperature conditions and exhibits metallic properties. This precompression effect is reflected in the formation of C-H bonds within the cage and C-C bonds between cages, resulting in the transformation of all C atoms from sp2 to sp3 hybridization with inward and outward distortions, while promoting delocalized multicenter bonding within the H9 aggregate. In particular, the hydrogen density inside the C20 cage exceeds that of solid hydrogen, achieving a uniform discrete distribution with H9 as monomers. Further study reveals that filling hydrogen molecules into voids between H9@C20 primitive cells can increase hydrogen content while maintaining structural stability, forming a solid-gas mixed hydrogen storage crystal. Our findings provide a basis for developing high-density hydrogen storage materials under ambient conditions.
Materials Science (cond-mat.mtrl-sci), Atomic and Molecular Clusters (physics.atm-clus), Chemical Physics (physics.chem-ph)
23 pages, 5 figures
Exact Identity Linking Entropy Production and Mutual Information
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Linking entropy production (EP) to information is a key step toward data-driven nonequilibrium thermodynamics. We derive an exact identity for overdamped Langevin dynamics that equates the total EP rate to the mutual-information rate between an infinitesimal displacement and its time-symmetric midpoint, up to a bulk mean-flow contribution. This mapping elevates information theory to a thermodynamic calculus: the chain rule yields a canonical, nonnegative split into self and interaction EP, and leads to a tighter bound on learning rate with interaction EP as the necessary cost. As a proof of concept, applying the estimator to red-blood-cell flickering shows that interaction EP robustly exposes active signatures that conventional summaries can miss.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Data Analysis, Statistics and Probability (physics.data-an)
5 pages, 4 figures
Hierarchical Dynamics and Time-Length Scale Superposition in Glassy Suspensions of Ultra-Low Crosslinked Microgels
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
A. Martinelli, R. Elancheliyan, A. Scotti, A. V. Petrunin, D. Truzzolillo, L. Cipelletti
We employ small-angle X-ray and dynamic light scattering to investigate the microscopic structure and dynamics of dense suspensions of ultra-low crosslinked (ULC) poly(N-isopropylacrylamide) (PNIPAM) microgels. By probing the supercooled and glassy regimes, we characterize the relationship between structure and dynamics as a function of effective volume fraction $ \phi$ and probed length scale. We demonstrate that ULC microgels act as fragile glass formers whose dynamics are governed solely by $ \phi$ . In contrast, the microscopic structure depends on the specific combination of microgel number density and swelling state that define $ \phi$ . We identify an anomalous glassy regime where relaxation times are orders of magnitude faster than predicted by supercooled extrapolations, and show that in this regime dynamics are partly accelerated by laser light absorption. Finally, we show that the microscopic relaxation time measured for different $ \phi$ ‘s and at various scattering vectors may be rationalized by a ``time-length scale superposition principle’’ analogous to the time-temperature superposition used to scale onto a master curve rheology or dielectric relaxation data of molecular systems. Remarkably, we find that the resulting master curve also applies to a different microgel system [V. Nigro \textit{et al.}, Macromolecules \textbf{53}, 1596 (2020)], suggesting a general dynamical behavior of polymeric particles.
Soft Condensed Matter (cond-mat.soft)
8 Figures + 11 figures in the Supplemental Material
Towards autonomous time-calibration of large quantum-dot devices: Detection, real-time feedback, and noise spectroscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-01-01 20:00 EST
Anantha S. Rao, Barnaby van Straaten, Valentin John, Cécile X. Yu, Stefan D. Oosterhout, Lucas Stehouwer, Giordano Scappucci, M. D. Stewart Jr., Menno Veldhorst, Francesco Borsoi, Justyna P. Zwolak
The performance and scalability of semiconductor quantum-dot (QD) qubits are limited by electrostatic drift and charge noise that shift operating points and destabilize qubit parameters. As systems expand to large one- and two-dimensional arrays, manual recalibration becomes impractical, creating a need for autonomous stabilization frameworks. Here, we introduce a method that uses the full network of charge-transition lines in repeatedly acquired double-quantum-dot charge stability diagrams (CSDs) as a multidimensional probe of the local electrostatic environment. By accurately tracking the motion of selected transitions in time, we detect voltage drifts, identify abrupt charge reconfigurations, and apply compensating updates to maintain stable operating conditions. We demonstrate our approach on a 10-QD device, showing robust stabilization and real-time diagnostic access to dot-specific noise processes. The high acquisition rate of radio-frequency reflectometry CSD measurements also enables time-domain noise spectroscopy, allowing the extraction of noise power spectral densities, the identification of two-level fluctuators, and the analysis of spatial noise correlations across the array. From our analysis, we find that the background noise at 100~$ \mu$ \si{\hertz} is dominated by drift with a power law of $ 1/f^2$ , accompanied by a few dominant two-level fluctuators and an average linear correlation length of $ (188 \pm 38)$ ~\si{\nano\meter} in the device. These capabilities form the basis of a scalable, autonomous calibration and characterization module for QD-based quantum processors, providing essential feedback for long-duration, high-fidelity qubit operations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computer Vision and Pattern Recognition (cs.CV), Emerging Technologies (cs.ET), Quantum Physics (quant-ph)
12 pages, 4 figures
Microscopic Insights to the Ultralow Thermal Conductivity of Monolayer 1T-SnTe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Kemal Aziz, John E. Ekpe, Augustine O. Okekeoma, Stanley O. Ebuwa, Sylvester M. Mbam, Shedrack Ani, Malachy N. Asogwa, Richard A. Mangluhut, Anthony C. Iloanya, Fabian I. Ezema, Chinedu E. Ekuma
Two-dimensional (2D) metallic systems with intrinsically low lattice thermal conductivity are rare, yet they are of great interest for next-generation energy and electronic technologies. Here, we present a comprehensive first-principles investigation of monolayer tin telluride (SnTe2) in its 1T (CdI2-type, P3m1) structure. Our calculations establish its energetic and dynamical stability, confirmed by large cohesive (10.9 eV/atom) and formation (-4.06 eV/atom) energies and a phonon spectrum free of imaginary modes. The electronic band structure reveals metallicity arising from strong Sn-Te p orbital hybridization. Most importantly, phonon dispersion analysis uncovers a microscopic origin for the ultralow lattice thermal conductivity: the heavy mass of Te atoms, weak Sn-Te bonding, and flat acoustic branches that yield exceptionally low and anisotropic group velocities (~5.0 x 10^3 m/s), together with the absence of a phonon bandgap that enhances Umklapp scattering. These features converge to suppress phonon-mediated heat transport. Complementary calculations of the optical dielectric response and joint density of states reveal pronounced interband transitions and a plasmonic resonance near 4.84 eV, suggesting additional optoelectronic opportunities. These findings establish monolayer SnTe2 as a 2D material whose vibrational softness naturally enforces ultralow lattice thermal conductivity, underscoring its potential for thermoelectric applications.
Materials Science (cond-mat.mtrl-sci)
8 pages, 3 figures
Large language models and the entropy of English
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Colin Scheibner, Lindsay M. Smith, William Bialek
We use large language models (LLMs) to uncover long-ranged structure in English texts from a variety of sources. The conditional entropy or code length in many cases continues to decrease with context length at least to $ N\sim 10^4$ characters, implying that there are direct dependencies or interactions across these distances. A corollary is that there are small but significant correlations between characters at these separations, as we show from the data independent of models. The distribution of code lengths reveals an emergent certainty about an increasing fraction of characters at large $ N$ . Over the course of model training, we observe different dynamics at long and short context lengths, suggesting that long-ranged structure is learned only gradually. Our results constrain efforts to build statistical physics models of LLMs or language itself.
Statistical Mechanics (cond-mat.stat-mech), Computation and Language (cs.CL), Biological Physics (physics.bio-ph), Neurons and Cognition (q-bio.NC)
8 pages, 6 figures
Graphicality of power-law and double power-law degree sequences
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-01-01 20:00 EST
Pietro Valigi, M. Ángeles Serrano, Claudio Castellano, Lorenzo Cirigliano
The graphicality problem – whether or not a sequence of integers can be used to create a simple graph – is a key question in network theory and combinatorics, with many important practical applications. In this work, we study the graphicality of degree sequences distributed as a power-law with a size-dependent cutoff and as a double power-law with a size-dependent crossover. We combine the application of exact sufficient conditions for graphicality with heuristic conditions for nongraphicality which allow us to elucidate the physical reasons why some sequences are not graphical. For single power-laws we recover the known phase-diagram, we highlight the subtle interplay of distinct mechanisms violating graphicality and we explain why the infinite-size limit behavior is in some cases very far from being observed for finite sequences. For double power-laws we derive the graphicality of infinite sequences for all possible values of the degree exponents $ \gamma_1$ and $ \gamma_2$ , uncovering a rich phase-diagram and pointing out the existence of five qualitatively distinct ways graphicality can be violated. The validity of theoretical arguments is supported by extensive numerical analysis.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
16 pages, 7 figures
Best Practices for Modelling Electrides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Materials in which electrons occupy interstitial sites as anions are called electrides and exhibit unusual dimensionality-dependent electronic behavior. These properties make electrides attractive for catalysis, transparent conductors, and emergent quantum phenomena, yet their theoretical treatment remains challenging. In conventional materials, the ground-state atomic structure dictates the electronic configuration, whereas in electrides the electronic structure can instead govern the atomic arrangement. Here, the performance of commonly used exchange-correlation functionals is evaluated for representative one-, two-, and three-dimensional electrides. The results show that higher-cost approaches do not necessarily perform better across all cases, while standard methods capture the qualitative electride character and many key energetic and structural trends with surprising reliability. This behavior, likely arising from fortuitous error cancellation, supports the reliability of legacy studies in the field and the viability of efficient high-throughput exploration using low-cost methods. Overall, the findings support a tiered computational strategy for electride modelling, integrating system-specific heuristics with efficient first-principles screening. This approach balances computational feasibility with physical fidelity and underscores the continuing leadership of theory in the predictive discovery of electride materials across dimensionalities.
Materials Science (cond-mat.mtrl-sci)
13 pages, 5 figures
Numerical study of boson mixtures with multi-component continuous matrix product states
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-01-01 20:00 EST
Wei Tang, Benoît Tuybens, Jutho Haegeman
The continuous matrix product state (cMPS) ansatz is a promising numerical tool for studying quantum many-body systems in continuous space. Although it provides a clean framework that allows one to directly simulate continuous systems, the optimization of cMPS is known to be a very challenging task, especially in the case of multi-component systems. In this work, we have developed an improved optimization scheme for multi-component cMPS that enables simulations of bosonic quantum mixtures with substantially larger bond dimensions than previous works. We benchmark our method on the two-component Lieb-Liniger model, obtaining numerical results that agree well with analytical predictions. Our work paves the way for further numerical studies of quantum mixture systems using the cMPS ansatz.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
11 pages, 5 figures
Parity order as a fundamental driver of bosonic topology
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Symmetry-protected topological (SPT) phases in interacting bosonic systems have been extensively studied, yet most realizations rely on fine-tuned interactions or enlarged symmetries. Here we show that a qualitatively different mechanism–parity order coupled to bond dimerization–acts as a fundamental driver of bosonic topology. Using density matrix renormalization group simulations, we identify two distinct topological phases absent in the purely dimerized model: an SPT phase at half filling stabilized by positive parity coupling, and a topological phase at unit filling stabilized by negative coupling that can be adiabatically connected to a trivial phase without breaking any symmetry. Our results establish parity order as a new organizing principle for correlation-driven bosonic topology.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Fractal conduction pathways governing ionic transport in a glass
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-01-01 20:00 EST
J. L. Iguain, F. O. Sanchez-Varreti, M. A. Frechero
We present a systematic characterization of the fractal conduction pathways governing ionic transport in a non-crystalline solid below the glass-transition temperature. Using classical molecular dynamics simulations of lithium metasilicate, we combine mobility-resolved dynamical analysis with a real-space description of the regions explored by lithium ions. Ensemble-averaged velocity autocorrelation functions rapidly decorrelate and do not resolve the pronounced dynamic heterogeneity of the system, whereas single-ion analysis reveals short-lived episodes of nearly collinear motion. By mapping active-site clusters over increasing time windows, we show that ion-conducting pathways are quasi one-dimensional at short times and evolve into larger, branched structures characterized by a robust fractal dimension $ d_f\simeq1.7$ . This geometry persists while the silicate backbone remains structurally arrested, whereas near the glass-transition temperature the loss of structural memory leads to the reappearance of small clusters. These results provide a real-space structural interpretation of ionic transport in non-crystalline solids and support fractal pathway models of high-frequency ionic response.
Soft Condensed Matter (cond-mat.soft)
6 pages, 4 figures
Perturbative Kondo destruction and global phase diagram of heavy fermion metals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Yiming Wang, Shouvik Sur, Chia-Chuan Liu, Qimiao Si
Strange metals represent a foundational problem in quantum condensed matter physics, and heavy fermion systems provide a canonical setting to advance a general understanding. The concept of a Kondo destruction quantum critical point is widely invoked to describe the competition of the Kondo effect and the local-moment magnetism. Here, we develop a unified field-theoretic approach, analyzing this competition from a rare approach that is anchored by the magnetically ordered side. Our analysis reveals, for the first time within a renormalization group framework, a quantum critical point across which the Kondo effect goes from being destroyed to dominating. Our findings elucidate not only the Kondo destruction quantum criticality but also an accompanying global phase diagram of heavy fermion metals.
Strongly Correlated Electrons (cond-mat.str-el)
6+12 pages, 5+5 figures
Emergence of 3D Superconformal Ising Criticality on the Fuzzy Sphere
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Yin Tang, Cristian Voinea, Liangdong Hu, Zlatko Papić, W. Zhu
Supersymmetric conformal field theories (SCFTs) form a unique subset of quantum field theories which provide powerful insights into strongly coupled critical phenomena. Here, we present a microscopic and non-perturbative realization of the three-dimensional $ \mathcal{N}=1$ superconformal Ising critical point, based on a Yukawa-type coupling between a 3D Ising CFT and a gauged Majorana fermion. Using the recently developed fuzzy sphere regularization, we directly extract the scaling dimensions of low-lying operators via the state-operator correspondence. At the critical point, we demonstrate conformal multiplet structure together with the hallmark of emergent spacetime supersymmetry through characteristic relations between fermionic and bosonic operators. Moreover, by tuning the Yukawa coupling, we explicitly track the evolution of operator spectra from the decoupled Ising-Majorana fixed point to the interacting superconformal fixed point, revealing renormalization-group flow at the operator level. Our results establish a controlled, non-perturbative microscopic route to 3D SCFTs.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
6+8 pages, 6 figures
Melting curve of correlated iron at Earth’s core conditions from machine-learned DFT+DMFT
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-01-01 20:00 EST
Reliable constraints on iron’s melting curve at Earth’s inner-core boundary require accurate finite-temperature electronic correlations, yet DFT+DMFT calculations remain too costly for large-scale thermodynamic sampling. Here, we develop a machine-learning accelerator for charge self-consistent DFT+DMFT by training E(3)-equivariant graph neural networks to predict the local self-energy and Fermi level from atomic environments, providing an efficient warm start to the DMFT self-consistency loop. Using high-throughput data for Fe, FeO, and NiO, we obtain a 2-4 times reuduction in DMFT iterations. Leveraging this improvement, we generate correlated energies and forces for Fe at core pressures, train a neural-network interatomic potential, and determine the melting curve via two-phase coexistence simulations. We obtain a predicted melting temperature of 6225 K at 330 GPa.
Materials Science (cond-mat.mtrl-sci), Geophysics (physics.geo-ph)
7 pages, 3 figures
Classification of Interacting Topological Crystalline Superconductors in Three Dimensions and Beyond
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-01-01 20:00 EST
Shang-Qiang Ning, Xing-Yu Ren, Qing-Rui Wang, Yang Qi, Zheng-Cheng Gu
Although classification for free-fermion topological superconductors (TSC) is established, systematically understanding the classification of 3D interacting TSCs remains difficult, especially those protected by crystalline symmetries like the 230 space groups. We build up a general framework for systematically classifying 3D interacting TSCs protected by crystalline symmetries together with discrete internal symmetries. We first establish a complete classification for fermionic symmetry protected topological phases (FSPT) with purely discrete internal symmetries, which determines the crystalline case via the crystalline equivalence principle. Using domain wall decoration, we obtain classification data and formulas for generic FSPTs, what are suitable for systematic computation. The four layers of decoration data $ (n_1, n_2, n_3, \nu_4)$ characterize a 3D FSPT with symmetry $ G_b\times_{\omega_2}Z_2^f$ , corresponding to $ p+ip$ , Kitaev chain, complex fermion, and bosonic SPT layers. Inspired by previous works, a crucial aspect is the $ p+ip$ layer, where classification involves two possibilities: anti-unitary and infinite-order symmetries (e.g., translation). We show the former maps to some mirror FSPT classification with the mirror plane decorated by a $ p+ip$ superconductor, while the latter is determined by the free part of $ H^1(G_b, Z_T)$ , corresponding to weak TSCs. Another key point is the Kitaev chain decoration for the anti-unitary symmetries, which differs essentially from unitary ones. We explicitly obtain formulas for all three layers of decoration $ (n_2, n_3, \nu_4)$ , which are amenable to automatic computation. As an application, we classify the 230 space-group topological crystalline superconductors in interacting electronic systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
38 pages, 15 figures, 6 tables, all comments and suggestions are welcome
Randomization Times under Quantum Chaotic Hamiltonian Evolution
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-01-01 20:00 EST
Souradeep Ghosh, Nicholas Hunter-Jones, Joaquin F. Rodriguez-Nieva
Randomness generation through quantum-chaotic evolution underpins foundational questions in statistical mechanics and applications across quantum information science, including benchmarking, tomography, metrology, and demonstrations of quantum computational advantage. While statistical mechanics successfully captures the temporal averages of local observables, understanding randomness at the level of higher statistical moments remains a daunting challenge, with analytic progress largely confined to random quantum circuit models or fine-tuned systems exhibiting space-time duality. Here we study how much randomness can be dynamically generated by generic quantum-chaotic evolution under physical, non-random Hamiltonians. Combining theoretical insights with numerical simulations, we show that for broad classes of initially unentangled states, the dynamics become effectively Haar-random well before the system can ergodically explore the physically accessible Hilbert space. Both local and highly nonlocal observables, including entanglement measures, equilibrate to their Haar expectation values and fluctuations on polynomial timescales with remarkably high numerical precision, and with the fastest randomization occurring in regions of parameter space previously identified as maximally chaotic. Interestingly, this effective randomization can occur on timescales linear in system size, suggesting that the sub-ballistic growth of Renyi entropies typically observed in systems with conservation laws can be bypassed in non-random Hamiltonians with an appropriate choice of initial conditions.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
5 pages, 4 figures