CMP Journal 2025-10-06
Statistics
Nature Reviews Physics: 2
Physical Review Letters: 11
arXiv: 51
Nature Reviews Physics
Mechanobiology across timescales
Review Paper | Biological physics | 2025-10-05 20:00 EDT
Bo Cheng, Moxiao Li, Min Lin, Hui Guo, Feng Xu
Despite transformative advances in nanoscale microscopy and spatiotemporal genomics, a coherent understanding of how transient mechanical events drive long-term tissue development or pathology remains elusive, exposing critical gaps in linking mechanical signals to their biological consequences. To address this disconnect, we survey the literature on timescales of membrane mechanosensing, cytoplasmic mechanotransduction and nuclear mechanoresponse, emphasizing mechanoadaptive strategies such as talin filtering of mechanical noise through folding-unfolding dynamics and force-lifetime-dependent molecular stabilization to gate nuclear signalling. By compiling the MechanoTemporal Atlas, we highlight several frontiers, including the role of pulsatile cellular contractions in tissue morphogenesis through molecular frequency modulation, the propagation of rapid mechanical signals across cells, and the dynamic sensing of viscoelastic tissue properties via time-gated cellular protrusions. Bridging these timescales promises to provide insights into the role of mechanobiology in health and disease.
Biological physics, Molecular biophysics
Protocols and tools to enable reproducibility in 2D materials research
Review Paper | Design, synthesis and processing | 2025-10-05 20:00 EDT
Peter Bøggild, Timothy John Booth, Bjarke Sørensen Jessen, Abhay Shivayogimath, Nolan Lassaline, Stephan Hofmann, Oliver Burton, Kim Daasbjerg, Anders Smith, Kasper Nørgaard, Amaia Zurutuza, Terrance Barkan, Andrew J. Pollard
Despite the rapid growth of 2D materials research over the past two decades in both academic and industrial settings, there remain big challenges in producing consistent, reproducible results in the field. Subtle variations in methods or materials can lead to drastically different outcomes, undermining reliability and slowing down advances. However, owing to a culture of placing greater value on novelty rather than on reproducibility, little effort is expended in ensuring that results are collected and presented in a way that enables reproducibility. This Expert Recommendation presents two protocols that researchers can follow to improve reproducibility in 2D materials science, as well as practical recommendations on how researchers can engage constructively with funders, publishers and industry to create a stronger basis for reproducibility, transparency and trust in the field.
Design, synthesis and processing, Engineering, Graphene, Techniques and instrumentation, Two-dimensional materials
Physical Review Letters
Nonequilibrium Critical Scaling of a Squeezing Phase Transition
Article | Quantum Information, Science, and Technology | 2025-10-06 06:00 EDT
Arman Duha, Samuel E. Begg, and Thomas Bilitewski
We investigate phase transitions in the nonequilibrium dynamics of power-law interacting spin- bilayer XXZ models, which have recently been shown to allow generation of entanglement in the form of two-mode squeezing. We find a transition between a collective phase characterized by Heisenberg limi…
Phys. Rev. Lett. 135, 150401 (2025)
Quantum Information, Science, and Technology
Counting the Ground State Degeneracy by Evolution Methods
Article | Quantum Information, Science, and Technology | 2025-10-06 06:00 EDT
Zhen Guo and Li You
Counting ground state degeneracy of a -local Hamiltonian is important in many fields of physics. Its complexity class is harder than that of finding the ground state of a -local Hamiltonian. Very few methods can efficiently count the degeneracy of ground state while many are known for finding the …
Phys. Rev. Lett. 135, 150601 (2025)
Quantum Information, Science, and Technology
Experimental Efficient Source-Independent Quantum Secret Sharing against Coherent Attacks
Article | Quantum Information, Science, and Technology | 2025-10-06 06:00 EDT
Yi-Ran Xiao, Hua-Lei Yin, Wen-Ji Hua, Xiao-Yu Cao, and Zeng-Bing Chen
Source-independent quantum secret sharing (SI QSS), while essential for secure multi-user cryptographic operations in quantum networks, faces significant implementation challenges stemming from the inherent complexity of generating and distributing multipartite entangled states. Recently, a resource…
Phys. Rev. Lett. 135, 150801 (2025)
Quantum Information, Science, and Technology
Probing Dipolar Interactions between Rydberg Atoms and Ultracold Polar Molecules
Article | Atomic, Molecular, and Optical Physics | 2025-10-06 06:00 EDT
Lingbang Zhu, Jeshurun Luke, Roy Shaham, Yi-Xiang Liu, and Kang-Kuen Ni
We probe resonant dipolar interactions between ultracold molecules and Rydberg atoms in an optically trapped ensemble. Through state-selective ionization detection of the KRb molecules, we observe resonant energy transfer at 2.227 GHz from Rydberg atoms to molecules under a tunable exte…
Phys. Rev. Lett. 135, 153001 (2025)
Atomic, Molecular, and Optical Physics
Self-Bound Superfluid Membranes and Monolayer Crystals of Ultracold Polar Molecules
Article | Atomic, Molecular, and Optical Physics | 2025-10-06 06:00 EDT
Matteo Ciardi, Kasper Rønning Pedersen, Tim Langen, and Thomas Pohl
We investigate the physics of ultracold dipolar molecules using path-integral quantum Monte Carlo simulations, and construct the complete phase diagram extending from weak to strong interactions and from small to mesoscopic particle numbers. Our calculations predict the formation of self-bound quant…
Phys. Rev. Lett. 135, 153401 (2025)
Atomic, Molecular, and Optical Physics
Enhancement to Fusion Reactivity in Sheared Flows
Article | Plasma and Solar Physics, Accelerators and Beams | 2025-10-06 06:00 EDT
Henry Fetsch and Nathaniel J. Fisch
Sheared flow increases the reactivity of fusion plasma. In unmagnetized plasma with flow gradients comparable to the mean free path of reacting ions, fusion reactivity can be more than doubled. The effect is of particular relevance to inertial confinement fusion (ICF), where it allows implosion kine…
Phys. Rev. Lett. 135, 155101 (2025)
Plasma and Solar Physics, Accelerators and Beams
Resolving Elementary Steps of Vapor-Phase Dealloying via In Situ Transmission Electron Microscopy
Article | Condensed Matter and Materials | 2025-10-06 06:00 EDT
Xinyao Wang, Yanying Li, Yuqiao Zeng, Yanyue Wang, Mingwei Chen, Qing Chen, and Pan Liu
Nanopores evolve in dealloying to dictate alloy corrosion while enabling the creation of functional metallic nanomaterials. Yet, the nanoscale dynamics of the porosity evolution have long eluded experimental characterizations. With aberration-corrected transmission electron microscopy, we reveal the…
Phys. Rev. Lett. 135, 156201 (2025)
Condensed Matter and Materials
Electronic Correlations in Rhombohedral Graphene at Atomic Scale
Article | Condensed Matter and Materials | 2025-10-06 06:00 EDT
Yufeng Liu, Zonglin Li, Shudan Jiang, Min Li, Yu Gu, Kai Liu, Qia Shen, Liang Liu, Xiaoxue Liu, Dandan Guan, Yaoyi Li, Hao Zheng, Canhua Liu, Kenji Watanabe, Takashi Taniguchi, Jinfeng Jia, Tingxin Li, Guorui Chen, Jianpeng Liu, Can Li, Zhiwen Shi, and Shiyong Wang
Rhombohedral graphene (RG) has emerged as a promising platform for exploring exotic quantum phenomena, such as quantum magnetism, unconventional superconductivity, and fractional quantum anomalous Hall effects. Despite its potential, atomic-scale investigations of RG remain limited, hindering a deta…
Phys. Rev. Lett. 135, 156401 (2025)
Condensed Matter and Materials
Strongly Inhomogeneous Spin Dynamics Induced by Ultrashort Laser Pulses with a Gradient Intensity Profile
Article | Condensed Matter and Materials | 2025-10-06 06:00 EDT
T. T. Gareev, N. E. Khokhlov, L. Körber, and A. V. Kimel
The optical pump-probe technique is a common tool for the investigation of ultrafast spin dynamics, which usually utilizes single-diode detection averaging the dynamics over the pumped area. Using an ultrafast imaging technique, we show experimentally that a femtosecond laser pulse with a gradient d…
Phys. Rev. Lett. 135, 156701 (2025)
Condensed Matter and Materials
Twist Engineering of Anisotropic Excitonic and Optical Properties of a Two-Dimensional Magnetic Semiconductor
Article | Condensed Matter and Materials | 2025-10-06 06:00 EDT
Qiuyang Li, Xiaohan Wan, Senlei Li, Adam Alfrey, Wenhao Liu, Zixin Zhai, Wyatt Alpers, Yujie Yang, Irmina Wladyszewska, Christiano W. Beach, Liuyan Zhao, Bing Lv, Chunhui Rita Du, Kai Sun, and Hui Deng
The anisotropic lattice, spin, and exciton properties of CrSBr monolayers provide the necessary conditions for continuously tunable magnetic moments, exciton energy, and dielectric and optical anisotropies.
Phys. Rev. Lett. 135, 156901 (2025)
Condensed Matter and Materials
Motility-Induced Crystallization and Rotating Crystallites
Article | Polymers, Chemical Physics, Soft Matter, and Biological Physics | 2025-10-06 06:00 EDT
Max Philipp Holl, Alina Barbara Steinberg, Michael te Vrugt, and Uwe Thiele
Active soft matter frequently shows motility-induced phase separation, where self-propelled particles condensate into clusters with an inner liquidlike structure. Such activity may also result in motility-induced crystallization into clusters with an inner crystalline structure. We derive a higher-o…
Phys. Rev. Lett. 135, 158301 (2025)
Polymers, Chemical Physics, Soft Matter, and Biological Physics
arXiv
Unusual spin-triplet superconductivity in monolayer graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
In this paper we consider the phonons in monolayer graphene and we show the possibility for the spin-triplet superconducting excitations states by discretizing the single-particle excitations near Fermi wave vector. The molonayer graphene was supposed to be exposed under the influence of the external gate-potential and the local Coulomb interaction effects have been taken into account at each lattice site position in the monolayer. A sufficiently large temperature domain was found, where the superconducting order parameter is not vanishing. Corresponding to this, at the surprisingly high temperature limit, we obtain a narrow domain of the electron-phonon coupling parameter $ \lambda_{\rm eff}$ , emphasizing the superconducting state. We discuss the localizing role of Hubbard-$ U$ interaction and the effects external gate potential on the calculated physical parameters in the system. We explain the importance of the chemical potential in the formation of the superconducting state. We show the existence of a large superconducting band-gap in the system even in the case of the absence of the applied electric field potential.
Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 13 figures
Eur. Phys. J. B, 97:75 (2024)
Uncovering origins of heterogeneous superconductivity in La$_3$Ni$_2$O$_7$ using quantum sensors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-10-06 20:00 EDT
Srinivas V. Mandyam, Esther Wang, Zhipan Wang, Bijuan Chen, Nishan C. Jayarama, Anmay Gupta, Eric A. Riesel, Valery I. Levitas, Christopher R. Laumann, Norman Y. Yao
The family of nickelate superconductors have long been explored as analogs of the high temperature cuprates. Nonetheless, the recent discovery that certain stoichiometric nickelates superconduct up to high $ T_c$ under pressure came as a surprise. The mechanisms underlying the superconducting state remain experimentally unclear. In addition to the practical challenges posed by working in a high pressure environment, typical samples exhibit anomalously weak diamagnetic responses, which have been conjectured to reflect inhomogeneous `filamentary’ superconducting states. We perform wide-field, high-pressure, optically detected magnetic resonance spectroscopy to image the local diamagnetic responses of as grown La$ _3$ Ni$ _2$ O$ _7$ samples \emph{in situ}, using nitrogen vacancy quantum sensors embedded in the diamond anvil cell. These maps confirm significant inhomogeneity of the functional superconducting responses at the few micron scale. By spatially correlating the diamagnetic Meissner response with both the local tensorial stress environment, also imaged \emph{in situ}, and stoichiometric composition, we unravel the dominant mechanisms suppressing and enhancing superconductivity. Our wide-field technique simultaneously provides a broad view of sample behavior and excellent local sensitivity, enabling the rapid construction of multi-parameter phase diagrams from the local structure-function correlations observed at the sub-micron pixel scale.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Statistical Signatures of Integrable and Non-Integrable Quantum Hamiltonians
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Feng He, Arthur Hutsalyuk, Giuseppe Mussardo, Andrea Stampiggi
Integrability is a cornerstone of classical mechanics, where it has a precise meaning. Extending this notion to quantum systems, however, remains subtle and unresolved. In particular, deciding whether a quantum Hamiltonian - viewed simply as a matrix - defines an integrable system is far from obvious, yet crucial for understanding non-equilibrium dynamics, spectral correlations, and correlation functions in many-body physics. We develop a statistical framework that approaches quantum integrability from a probabilistic standpoint. A key observation is that integrability requires a finite probability of vanishing energy gaps. Building on this, we propose a two-step protocol to distinguish integrable from non-integrable Hamiltonians. First, we apply a systematic Monte Carlo decimation of the spectrum, which exponentially compresses the Hilbert space and reveals whether level spacings approach Poisson statistics or remain mixed. The termination point of this decimation indicates the statistical character of the spectrum. Second, we analyze $ k$ -step gap distributions, which sharpen the distinction between Poisson and mixed statistics. Our procedure applies to Hamiltonians of any finite size, independent of whether their structure involves a few blocks or an exponentially fragmented Hilbert space. As a benchmark, we implement the protocol on quantum Hamiltonians built from the permutation group $ \mathcal{S}_N$ , demonstrating both its effectiveness and generality.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
68+22 pages, 27 figures
Four Moiré materials at One Magic Angle in Helical Quadrilayer Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
Manato Fujimoto, Naoto Nakatsuji, Ashvin Vishwanath, Patrick Ledwith
We introduce helical twisted quadrilayer graphene (HTQG), four graphene sheets rotated by the same small angle, as a versatile and experimentally accessible platform for correlated topological matter. HTQG consists of three moiré lattices, formed by interference between adjacent graphene layers, that are twisted relative to each other. Lattice relaxation produces four types of large-scale commensurate domains. The domains are characterized by the stacking of the three moiré lattices and come in two types: Type-I “Bernal” stacking and Type-II “rhombohedral” stacking. Domain walls between adjacent stackings often host topologically protected edge states, forming networks at the supermoiré and super-supermoiré scales. Remarkably, all four moiré substructures have narrow bands at the same magic angle $ \theta \approx 2.3^\circ$ , allowing their correlated phases to be simultaneously targeted in device manufacturing. We argue that the Type-I domains are especially suitable for realizing robust superconductivity which emerges from doping topological insulators, and Chern insulators in $ C = \pm 2$ bands.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 3 figures main text. 9 pages 5 figures supplement
Finite-size fluctuations for stochastic coupled oscillators: A general theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Rupak Majumder, Julien Barré, Shamik Gupta
Phase transitions, sharp in the thermodynamic limit, get smeared in finite systems where macroscopic order-parameter fluctuations dominate. Achieving a coherent and complete theoretical description of these fluctuations is a central challenge. We develop a general framework to quantify these finite-size effects in synchronization transitions of generic stochastic, globally-coupled nonlinear oscillators. By applying a center-manifold reduction to the nonlinear stochastic PDE for the single-oscillator distribution in finite systems, we derive a mesoscopic description that yields the complete time evolution of the order parameter in the form of a Langevin equation. In particular, this equation provides the first closed-form steady-state distribution of the order parameter, fully capturing finite-size effects. Free from integrability constraints and the celebrated Ott-Antonsen ansatz, our theory shows excellent agreement with simulations across diverse coupling functions and frequency distributions, demonstrating broad applicability. Strikingly, it surpasses recent approaches near criticality and in the incoherent phase, where finite-size fluctuations are most pronounced.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
26 pages, 6 figures
Slow-phonon control of spin Edelstein effect in Rashba $d$-wave altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Mohsen Yarmohammadi, Jacob Linder, James K. Freericks
Altermagnets have zero net magnetization yet feature spin-split bands that host spin-polarized states. Here, we investigate how slow lattice vibrations (phonons) influence both the intrinsic and externally induced spin polarizations in two-dimensional $ d$ -wave altermagnets. For the induced spin polarizations, we employ a Rashba continuum model with electron-phonon coupling (EPC) treated at the static-Holstein level and analyze the spin Edelstein effect using the Kubo linear-response formalism. We find that moderate-to-strong EPC progressively suppresses the induced polarization via both intraband and interband channels, with a critical coupling marking the onset of complete spin Edelstein depolarization. The depolarization transition arises from a phonon-induced energy renormalization that pushes the spin-split bands anisotropically above the chemical potential, leading to a complete collapse of the Fermi surface. While (de)polarization can occur even in the Rashba non-altermagnetic phase, it remains isotropic. The presence of altermagnetism makes it anisotropic and breaks the conventional antisymmetry between spin susceptibilities that occurs with pure spin-orbit coupling, rendering the effect highly relevant for spintronic applications. We further investigate how the phonon coupling to the altermagnetic order, Rashba spin-orbit strength, and carrier doping collectively tune the depolarization transition. Our findings demonstrate that phonon scattering (e.g., through various substrates) offers a powerful means for on-demand control of spin polarization, enabling reversible switching between spin-polarized and depolarized states – a key functionality for advancing spin logic architectures and optimizing next-generation spintronic devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
14 pages, 8 figures
Spin polarization engineering in $d$-wave altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Mohsen Yarmohammadi, Marco Berritta, Marin Bukov, Libor Šmejkal, Jacob Linder, Peter M. Oppeneer
Altermagnets host unconventional spin-polarized bands despite zero net magnetization, but controlling their spin structure remains challenging. We propose a multi-field approach to engineer spin polarization in $ d$ -wave altermagnets using gating, optical driving, and in-plane electric fields, which enable tunable and switchable polarizations along multiple directions. Optical driving induces out-of-plane ($ z$ ) polarization, while gating and in-plane fields generate $ x$ - and $ y$ -polarizations via the Edelstein effect, all of which are experimentally detectable. We further find that spin- and band-selective doping induces chiral optical activity, a feature unique to altermagnets. Our approach provides a versatile route for full control of spin polarization in altermagnets.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 4 figures
One-dimensional long-range Ising model: two (almost) equivalent approximations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Valerio Pagni, Guido Giachetti, Andrea Trombettoni, Nicolò Defenu
We investigate the critical behavior of the one-dimensional Ising model with long-range interactions using the functional renormalization group in the local potential approximation (LPA), and compare our findings with Dyson’s hierarchical model (DHM). While the DHM lacks translational invariance, it admits a field-theoretical description closely resembling the LPA, up to minor but nontrivial differences. After reviewing the real-space renormalization group approach to the DHM, we demonstrate a remarkable agreement in the critical exponent $ \nu$ between the two methods across the entire range of power-law decays $ 1/2 < \sigma < 1$ . We further benchmark our results against Monte Carlo simulations and analytical expansions near the upper boundary of the nontrivial regime, $ \sigma \lesssim 1$ .
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
Detecting quantum spin liquid on Kitaev model through a superconducting junction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
The Kitaev model belongs to an unconventional class of two-dimensional spin systems characterized by anisotropic, bond-dependent interactions that give rise to Quantum Spin Liquid (QSL) states. These exotic phases, marked by the absence of magnetic ordering even at zero temperature, support fractionalized excitations and emergent gauge fields. A particularly compelling feature of the Kitaev model is its exact solvability, which reveals low-energy excitations in the form of itinerant Majorana fermions-quasiparticles that obey non-Abelian statistics and are of central interest in topological quantum computation due to their inherent robustness against local perturbations and decoherence. Despite extensive theoretical advancements, the experimental identification of QSLs remains challenging, as conventional magnetic probes fail to detect their defining properties. In this work, we present a theoretical investigation of spin current injection from a superconducting metal into a Kitaev quantum spin liquid. By employing a spintronic framework, we derive the dynamics of the injected spin current and demonstrate how its signatures can be traced back to the underlying Majorana excitations in the spin liquid phase. Superconductivity plays a pivotal role in this context, not only as a source of coherent quasiparticles but also as a platform with potential for interfacing with topological quantum devices. Our analysis contrasts the Kitaev-superconductor interface with conventional ferromagnetic junctions, where spin transport is carried by magnons, and highlights distinctive features in the spin current response. These findings open new directions for the detection of QSLs and contribute to the broader effort of integrating topological quantum materials into scalable quantum technologies.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 6 figures
Turbulent Dynamics in Active Solids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-10-06 20:00 EDT
Wilhelm Sunde Lie, Ingve Simonsen, Paul Gunnar Dommersnes
We investigate numerically the polar ordering dynamics in the active elastic solid model (AES) and find classic signatures of turbulent dynamics: power-law scaling for the energy spectrum and non-Gaussian statistics of velocity increments. However, there is no energy cascade, in line with previous findings for active turbulence in fluids. The results extend the concept of active turbulence to solid systems and are expected to be important for understanding active biological solids, such as bacterial colonies and migrating epithelial monolayers.
Soft Condensed Matter (cond-mat.soft)
5 pages, 4 figures
Vestigial pairing from fluctuating magnetism and triplet superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-10-06 20:00 EDT
Yanek Verghis, Denis Sedov, Jakob Weßling, Prathyush P. Poduval, Mathias S. Scheurer
We study the finite-temperature vestigial superconducting phases of a two-dimensional system of fluctuating spin-triplet pairing and spin magnetism. Denoting the respective primary order parameters by $ \mathbf{d}$ and $ \mathbf{N}$ , which are not long-range ordered at finite temperature, the composite fields $ \phi_{dd} = \mathbf{d}\cdot\mathbf{d}$ and $ \phi_{dN} = \mathbf{d}\cdot\mathbf{N}$ are spin-rotation invariant and can condense at finite temperature. Using a large-$ N$ approach that respects the Mermin-Wagner theorem, we here derive the phase diagram which features two vestigial superconductors: $ (A)$ a charge-$ 4e$ superconductor with $ \phi_{dd}\neq 0$ and $ \phi_{dN} =0$ and $ (B)$ a charge-$ 2e$ state with $ \phi_{dN} ,\phi_{dd}\neq 0$ . We analyze the temperature and coupling-constant dependent properties of these two superconductors using a perturbative approach and a variational Hartree-Fock study. This reveals non-trivial spectra in the superconductors, which result from the fundamental building blocks being distinct from the usual Cooper pairs–in phase $ (A)$ , the elementary bosons are bound states of four electrons and, in phase $ (B)$ , of three electrons and a hole. This work complements the previous study [Nat. Commun. 15, 1713 (2024), arXiv:2301.01344], which focused on the properties of phase $ (B)$ .
Superconductivity (cond-mat.supr-con)
Symmetry in magnetoelectric electromagnetism and magnetoelectric meta-atoms
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
While in electromagnetism we have space-time symmetry, magnetoelectric (ME) processes are characterized by space-time symmetry breaking. Our goal is to show that quantum vacuum fields with both time reversal and space inversion symmetry breaking (so-called ME fields) can be observed in subwavelength regions of electromagnetic (EM) radiation. The sources of ME fields are ME meta-atoms, subwavelength elements made of magnetic insulators, where the dynamical ME behavior is due to modulations and topological coupling of magnetization and electric polarization. The interaction between EM and ME systems occurs through virtual structures, ME virtual photons. Experimentally, ME quantum vacuum states can be detected in a microwave cavity. The topic of these studies concerns fundamental aspects of ME quantum electrodynamics (MEQED).
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Optics (physics.optics)
Epitaxially-stabilized growth of wüstite FeO on 4H-SiC
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Faisal Kimbugwe, Marzieh Baan, Alexandra Fonseca Montenegro, Roberto C Myers, Tyler J Grassman
Iron(II) monoxide (FeO) is thermodynamically stable in the halite (wüstite) structure only at elevated temperatures in a typically non-stoichiometric, Fe-deficient, Fe$ _{1-z}$ O form that tends to phase separate and/or transform into metallic $ \alpha$ -Fe and magnetite Fe$ _3$ O$ _4$ at ambient conditions. Here we report on the successful growth of up to 180 nm thick $ (111)$ -oriented FeO heteroepitaxial films on slightly lattice-matched 4H-SiC$ (0001)$ using molecular beam epitaxy (MBE). The films have flat, terraced surfaces with tall multi-layer steps. X-ray diffraction (XRD), high-resolution scanning transmission electron microscopy (S/TEM), energy-dispersive X-ray spectroscopy (EDS), and core-level electron energy loss spectroscopy (EELS) collectively confirm the epilayer as phase-pure wüstite FeO, with atomically sharp FeO/SiC interfaces. The films are found to exhibit a slight misfit strain-induced rhombohedral distortion that does not appear to vary over the range of thicknesses examined. These results demonstrate the power of epitaxial stabilization for integrating a thermodynamically unstable, yet functionally interesting material with a commercially available and technologically important semiconductor platform.
Materials Science (cond-mat.mtrl-sci)
Active-Learning Inspired Ab Initio Theory-Experiment Loop Approach for Management of Material Defects: Application to Superconducting Qubits
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Sarvesh Chaudhari, Cristobal Mendez, Rushil Choudhary, Tathagata Banerjee, Maciej Olszewski, Jadrien Paustian, Jaehong Choi, Zhaslan Baraissov, Raul Hernandez, David Muller, Britton Plourde, Gregory Fuchs, Valla Fatemi, Tomas Arias
Surface oxides are associated with two-level systems (TLSs) that degrade the performance of niobium-based superconducting quantum computing devices. To address this, we introduce a predictive framework for selecting metal capping layers that inhibit niobium oxide formation. Using DFT-calculated oxygen interstitial and vacancy energies as thermodynamic descriptors, we train a logistic regression model on a limited set of experimental outcomes to successfully predict the likelihood of oxide formation beneath different capping materials. This approach identifies Zr, Hf, and Ta as effective diffusion barriers. Our analysis further reveals that the oxide formation energy per oxygen atom serves as an excellent standalone descriptor for predicting barrier performance. By combining this new descriptor with lattice mismatch as a secondary criterion to promote structurally coherent interfaces, we identify Zr, Ta, and Sc as especially promising candidates. This closed-loop strategy integrates first-principles theory, machine learning, and limited experimental data to enable rational design of next-generation materials.
Materials Science (cond-mat.mtrl-sci)
7 pages, 6 figures (7 images)
Finite-size and quenching effects on hyperuniform structures formed during cooling
New Submission | Superconductivity (cond-mat.supr-con) | 2025-10-06 20:00 EDT
A. Cruz-García, J. Puig, R. M. Besana, A. B. Kolton, Y. Fasano
The outstanding physical properties of hyperuniform condensed matter systems holds significant promise for technological applications and studying effects that may disrupt this hidden order is therefore very important. Vortex matter in superconductors is a model system to study this problem since imaging experiments have revealed that correlated disorder in the host media and finite size effects disrupt the hyperuniformity of the in-plane arrangement of vortices. Here we report simulations of layered interacting elastic lines as a model for the vortex lattice in three-dimensional superconductors, following a cooling protocol that closely mimics the experimental conditions. We show that finite-thickness effects limiting the hyperuniformity range arise both in equilibrium and out-of-equilibrium. Our results provide a theoretical framework to draw a realistic road-map on synthesizing hyperuniform materials when cooling structures on finite host media with disorder.
Superconductivity (cond-mat.supr-con)
14 pages, 12 figures
Learning Microswimmer Collision Dynamics and Predicting Diffusivities using a Neural-Network-Assisted Boltzmann Approach
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-10-06 20:00 EDT
Haruki Hayano, Akira Furukawa, Kang Kim
We present a neural-network–assisted Boltzmann framework that learns the binary-collision map of microswimmers from data and uses it to evaluate collision integrals efficiently. Using a representative model swimmer, the learned map provides quantitative predictions for rotational and translational diffusivities and allows a linear-stability analysis of the isotropic state against polar ordering in dilute suspensions. The resulting predictions closely match direct simulations in the dilute regime. The present approach is model agnostic: once two-body collision data are available – either from simulations or experiments – the same surrogate can be used to perform these evaluations across dilute conditions, as long as two-body collision processes dominate. Because the workflow relies only on pre- and post-collision statistics, it can be applied directly to a wide range of biological and synthetic colloidal swimmer systems.
Soft Condensed Matter (cond-mat.soft)
5 pages, 4 figures
A Physical Unclonable Function Based on Variations of Write Times in STT-MRAM due to Manufacturing Defects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Jacob Huber, Supriyo Bandyopadhyay
A physical unclonable function (PUF) utilizes the unclonable random variations in a device’s responses to a set of inputs to produce a unique “biometric” that can be used for authentication. The variations are caused by unpredictable, unclonable and random manufacturing defects. Here, we show that the switching time of a magnetic tunnel junction injected with a spin-polarized current generating spin transfer torque is sensitive to the nature of structural defects introduced during manufacturing and hence can be the basis of a PUF. We use micromagnetic simulations to study the switching times under a constant current excitation for six different (commonly encountered) defect morphologies in spin-transfer-torque magnetic random access memory (STT-MRAM) to establish the viability of a PUF.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
The line bundle regime and the scale-dependence of continuum dislocation dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Joseph Pierre Anderson, Anter El-Azab
Continuum dislocation dynamics (CDD) has become the state-of-the-art theoretical approach for mesoscale dislocation plasticity of metals. Within this approach, there are multiple CDD theories that can all be derived from the principles of statistical mechanics. In these theories density-based measures are used to represent dislocation lines. Establishing these density measures requires some level of coarse graining with the result of losing track of some parts of the dislocation population due to cancellation in the tangent vectors of unaligned dislocations. The leading CDD theories either treat dislocations as nearly parallel or distributed locally over orientation space. The difference between these theories is a matter of the spatial resolution at which the definition of the relevant dislocation density field holds: for fine resolutions, single dislocations are resolved and there is no cancellation; for coarse resolutions, whole dislocation loops could contribute at a single point and there is complete cancellation. In the current work, a formulation of the resolution-dependent transition between these limits is presented in terms of the statistics of dislocation line orientation fluctuations about a local average line direction. From this formulation, a study of the orientation fluctuation behavior in intermediate resolution regimes is conducted. Two possible closure equations for truncating the moment sequence of the fluctuation distributions relating the two theories mentioned above are evaluated from data, the newly introduced line bundle closure and the previous standard maximum entropy closure relations. The line bundle closure relation is shown to be accurate for coarse-graining lengths up to half the dislocation spacing and the maximum entropy closure is found to poorly agree with the data at all coarse-graining lengths.
Materials Science (cond-mat.mtrl-sci)
Spin-dependent orbital selectivity and partial Kondo-screening in magnetically ordered Hund’s metal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
Shivani Bhardwaj, Sudhir K. Pandey
Hund’s metallicity in 3$ d$ transition metal oxides constitutes a rare class of compounds, since they have been long understood considering the dominance of Hubbard $ U$ . $ \mathrm{LiV_2O_4}$ & $ \mathrm{Sr_2CoO_4}$ belong to this rare class of metals; among them, $ \mathrm{LiV_2O_4}$ has been the subject of extensive investigations for its unconventional heavy-fermion behavior, while studies on $ \mathrm{Sr_2CoO_4}$ remain limited despite its anomalous ferromagnetic ground state. In this study, we report an unusual spin-orbital selective localization in $ \mathrm{Sr_2CoO_4}$ leading to a sharp Kondo resonance at $ \sim$ 70 K in the spin-$ up$ channel of orbitals of $ t_{2g}$ symmetry using a combination of Density functional theory and Dynamical mean field theory (DFT+DMFT) calculations. Correspondingly, an appreciable reduction in the magnetization below $ T$ =100 K further suggests partial Kondo screening of local moments active at low temperatures, explaining its effective spin magnetization state and upturn in its resistivity observed in experimental reports. We note a significant effect of Hund’s induced spin-orbital selective incoherence in dictating the temperature evolution of its macroscopic observables e.g. spin-spin correlation function and effective local moment. Our results reveal a potentially distinct/new form of spin-dependent selectivity induced via Hund’s coupling in addition to the conventional orbital-selectivity in the Hund’s metals, as a plausible key mechanism in stabilizing their long-range magnetic order.
Strongly Correlated Electrons (cond-mat.str-el)
Improper-proper ferroelectric competition as a mechanism for multistate polarisation and ferrielectric-like behaviour
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Cameron A.M Scott, Finlay D. Morrison, Nicholas. C. Bristowe
In this paper, we re-explore a simple textbook Landau model describing improper ferroelectricity and show that in the limit where both proper and improper instabilities exist and compete, improper ferroelectrics can display switching between multiple polarisation states. Using first principles calculations we highlight how the hexagonal tungsten bronze materials may be an archetypal case, with the possibility to switch between improper and proper phases. The resulting functional characteristics are akin to “ferrielectrics”, with switching behaviour in the form of a triple hysteresis loop. Such functionality could be ideal for creating non-volatile multistate systems for use in memory devices or as a backbone for neuromorphic computing.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
23 pages including 15 pages of supplemental information
Ginzburg-Landau theory of spin pumping through an antiferromagnetic layer near the Néel temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Yuto Furutani, Hayato Fukushima, Yutaka Yamamoto, Masanori Ichioka, Hiroto Adachi
Spin pumping is a microwave-driven means for injecting spins from a ferromagnet into the adjacent target material. The insertion of a thin antiferromagnetic layer between the ferromagnet and the target material is known to enhance the spin pumping signal. Here, in view of describing dynamic fluctuations of the Néel order parameter, we develop Ginzburg-Landau theory of the spin pumping in a ferromagnet/antiferromagnet/heavy metal trilayer in the vicinity of the antiferromagnetic Néel temperature $ T_{\rm N}$ . When there exists an interfacial exchange interaction between the ferromagnetic spins and the antiferromagnetic Néel order parameter at the ferromagnet/antiferromagnet interface, we find a strongly frequency-dependent enhancement of the pumped spin current that is peaked at $ T_{\rm N}$ . The present finding offers an explanation for the enhanced spin pumping with strong frequency dependence observed in a Y$ _3$ Fe$ _5$ O$ _{12}$ /CoO/Pt system.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
13 pages, 4 figures
Classification of electromagnetic responses by quantum geometry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Longjun Xiang, Jinxiong Jia, Fuming Xu, Jian Wang
The nonlinear charge current $ j_a=\sigma_{abc}E_bE_c$ of Bloch electrons in quantum materials under an electric field can be well characterized by the quantum geometry, as most exemplified by the extrinsic and intrinsic nonlinear Hall effects induced by the Berry curvature dipole and the quantum metric dipole, respectively. Nevertheless, a unified quantum geometric description for the bilinear charge current $ j_a=\sigma_{ab,c}E_bB_c$ of Bloch electrons driven by the electromagnetic fields, including the ordinary Hall effect (OHE), the magnetononlinear Hall effect (MNHE), and the planar Hall effect (PHE), remains elusive. Herein, we show that this bilinear conductivity, as contributed by the orbital minimal coupling and the spin Zeeman coupling of the applied magnetic field, respectively, can be classified by the conventional quantum geometry and the recently proposed Zeeman quantum geometry, where the symmetry constraint from the fundamental response equation is encoded. Specifically, we uncover that the intrinsic orbital and spin bilinear currents–responsible for the orbital and spin MNHEs–are governed by the quantum metric quadrupole and the Zeeman quantum metric dipole, respectively. In contrast, the extrinsic orbital and spin bilinear currents, which are linear in the relaxation time $ \tau$ and lead to the orbital and spin PHEs, are governed by the Berry curvature quadrupole and the Zeeman Berry curvature dipole, respectively. Counterintuitively, we find that the OHE due to the Lorentz force can also include an interband contribution from the quantum metric quadrupole. After building the quantum geometric classification of this bilinear current, we study the rarely known spin PHE with the surface Dirac cone of three-dimensional topological insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Kolmogorov-Arnold Networks in Thermoelectric Materials Design
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Marco Fronzi, Michael J. Ford, Kamal Singh Nayal, Olexandr Isayev, Catherine Stampfl
The discovery of high-performance thermoelectric materials requires models that are both accurate and interpretable. Traditional machine learning approaches, while effective at property prediction, often act as black boxes and provide limited physical insight. In this work, we introduce Kolmogorov–Arnold Networks (KANs) for the prediction of thermoelectric properties, focusing on the Seebeck coefficient and band gap. Compared to multilayer perceptrons (MLPs), KANs achieve comparable predictive accuracy while offering explicit symbolic representations of structure–property relationships. This dual capability enables both reliable predictions and the extraction of physically meaningful functional forms. Benchmarking against literature models further highlights the robustness and generalisability of the approach. Our findings demonstrate that KANs provide a powerful framework for reverse engineering materials with targeted thermoelectric properties, bridging the gap between predictive performance and scientific interpretability.
Materials Science (cond-mat.mtrl-sci)
15 pages , 11 figures, 6 tables
Weak localization and antilocalization corrections to nonlinear transport: a semiclassical Boltzmann treatment
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
The nonlinear transport regime is manifested in the nonlinear current-voltage characteristic of the system. An example of such a nonlinear regime is a setup in which current is injected into the sample and the measured voltage drop is quadratic in the injected current. Such a quadratic nonlinear regime requires inversion symmetry to be broken. This is the same symmetry condition as one needs to observe weak antilocalization, which can be prominent in two-dimensional systems. Here, we study the effects of weak (anti)localization on second-order nonlinear transport in two-dimensional systems using the semiclassical Boltzmann approach. We solve for quasiparticle distribution function up to the second order in the applied external electric field and calculate linear and nonlinear conductivity tensors for a toy model. We find that localization effects could lead to a sign change of the nonlinear conductivity tensor – a phenomenon observed in single-layer graphene devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Main text: 4 pages, 1 figure, 32 references; Supplementary information: 9 pages, 1 figure
Spectroscopic evidence of Kondo resonance in 3$d$ van der Waals ferromagnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
Deepali Sharma, Neeraj Bhatt, Asif Ali, Rajeswari Roy Chowdhury, Chandan Patra, Ravi Prakash Singh, Ravi Shankar Singh
Two-dimensional van der Waals (vdW) ferromagnets drive the advancement in spintronic applications and enable the exploration of exotic magnetism in low-dimensional systems. The entanglement of dual $ -$ localized and itinerant $ -$ nature of electrons lies at the heart of the correlated electron systems giving rise to exotic ground state properties such as complex magnetism, heavy fermionic behavior, Kondo lattice formation, \textit{etc}. Through temperature-dependent electronic structure of vdW ferromagnets, (Co$ _{x}$ Fe$ _{1-x}$ )$ {3}$ GeTe$ {2}$ , probed using high-resolution photoemission spectroscopy and density functional theory combined with dynamical mean field theory (DFT+DMFT), we provide direct evidence of the emergence of Kondo resonance peak driven by complex interplay between localized and itinerant electrons. In overall agreement with experimental electronic structure and magnetic properties, DFT+DMFT also reveals finite spin band splitting well beyond $ T{C}$ . Core levels, valence band photoemission spectra together with DFT+DMFT spectral functions reveal insignificant change across $ T{C}$ indicating non-Stoner magnetism in (Co$ _{x}$ Fe$ _{1-x}$ )$ _{3}$ GeTe$ _{2}$ . Our results provide a way forward to the understanding of complex interplay between electronic structure, exotic magnetism and heavy fermionic behavior leading to Kondo scenerio in 3$ d$ vdW ferromagnets.
Strongly Correlated Electrons (cond-mat.str-el)
to appear in Phys. Rev. B
Bimagnon dispersion of La2CuO4 probed by resonant inelastic X-ray scattering
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
A. Singh, H. Y. Huang, K. Tsutsui, T. Tohyama, S. Komiya, J. Okamoto, C. T. Chen, A. Fujimori, D. J. Huang
We report on the study of the magnetic excitations of Mott insulator La2CuO4 by using resonant inelastic x-ray scattering (RIXS) and cluster calculations within the framework of exact diagonalization. Our results demonstrate experimentally that the bimagnon excitation in Cu L-edge RIXS is enhanced if the incident x-ray energy is slightly above the absorption edge. Through incident-energy-dependent momentum-resolved RIXS, we investigated the excitation of the bimagnon with predominantly A1 symmetry. The bimagnons of La2CuO4 exhibit a nearly flat dispersion with momentum along the Cu-O bond direction. This observation agrees with the bimagnon dispersion from the calculations on a single-band Hubbard model rather than a Heisenberg model with only the nearest neighbor exchange interaction. This means that the effect of the higher-order spin couplings such as the cyclic or ring exchange interactions caused by the coherent motion of electrons beyond nearest-neighbor sites is important for understanding the bimagnon dynamics of cuprates.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Scientific Reports (2025) 15:34183
Magnetocaloric effect for the altermagnetic candidate MnTe
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
N.N. Orlova, V.D. Esin, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov
We experimentally investigate magnetocaloric effect for single crystals of MnTe altermagnet at the transition to the state with spontaneous spin polarization, i.e. well below the Néel temperature of MnTe. The isothermal magnetic entropy change $ \Delta S$ is calculated from the experimental magnetization curves by using Maxwell relation. We observe well-defined magnetocaloric effect as a narrow $ \Delta S$ peak around the cricital temperature $ T_c\approx 81$ ~K, which is accompanied by sharp magnetization jump. This behavior is unusual for standard ferromagnetic transitions, so it confirms the predicted spin-orbit-induced spin polarization in the MnTe altermagnetic state.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Photovoltaic Performance of a Rotationally Faulted Multilayer Graphene/n-Si Schottky Junction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
We report the fabrication and photovoltaic performance of a rotationally faulted multilayer graphene (rf-MLG)/n-Si Schottky junction device. A thickness-controlled rf-MLG is synthesized using a 5 {\mu}m Ni foil catalyst via the chemical vapor deposition method and transferred to the n-Si substrate via a polymer-free process, enabling facile and cost-effective fabrication. The device demonstrates an ideality factor of 1.67, a rectification factor of approximately 4x10^5 at {\pm}1.0 V, and a Schottky barrier height of 0.83 eV. A strong linear relationship between light intensity and photocurrent is also observed. Furthermore, the device exhibits a peak external quantum efficiency of ~26% at 540 nm and a peak internal quantum efficiency of ~97% at 410 nm. Transient photocurrent and photovoltaic measurements show approximately one-microsecond extraction and several-millisecond recombination times, respectively, revealing effective charge collection for photovoltaic applications. These results indicate that the rf-MLG/n-Si Schottky junction is well-formed and achieves performance comparable to that of SLG devices, demonstrating its potential for optoelectronic applications.
Materials Science (cond-mat.mtrl-sci)
25 pages, 9 figures
Diamond & Related Materials 159 (2025) 112910
Using Landau quantization to probe disorder in semiconductor heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Asser Elsayed, Davide Costa, Lucas E. A. Stehouwer, Alberto Tosato, Mario Lodari, Brian Paquelet Wuetz, Davide Degli Esposti, Giordano Scappucci
Understanding scattering mechanisms in semiconductor heterostructures is crucial to reducing sources of disorder and ensuring high yield and uniformity in large spin qubit arrays. Disorder of the parent two-dimensional electron or hole gas is commonly estimated by the critical, percolation-driven density associated with the metal-insulator transition. However, a reliable estimation of the critical density within percolation theory is hindered by the need to measure conductivity with high precision at low carrier densities, where experiments are most difficult. Here, we connect experimentally percolation density and quantum Hall plateau width, in line with an earlier heuristic intuition, and offer an alternative method for characterizing semiconductor heterostructure disorder.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
A physics-informed neural network approach to the point defect model for electrochemical oxide film growth
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Mohid Farooqi, Ingmar Bösing, Conrad G. Tetsassi Feugmo
Physics-informed neural networks (PINNs) offer a novel AI-driven framework for integrating physical laws directly into neural network models, facilitating the solution of complex multiphysics problems in materials engineering. This study systematically explores the application of PINNs to simulate oxide film layer growth in halide-free solutions using the point defect model (PDM). We identify and analyze four key failure modes in this context: imbalanced loss components across different physical processes, numerical instabilities due to variable scale disparities, challenges in enforcing boundary conditions within multiphysics systems, and convergence to mathematically valid but physically meaningless solutions. To overcome these challenges, we implement and validate established techniques including nondimensionalization for training stabilization, Neural Tangent Kernel-based adaptive loss balancing, and robust enforcement of boundary conditions. Our results demonstrate the effectiveness of these strategies in enhancing the reliability and physical fidelity of PINN simulations in electrochemical physics, highlighting the novelty and practical impact of our approach.
Materials Science (cond-mat.mtrl-sci)
Redox Chemistry of LiCoO$2$, LiNiO$2$, and LiNi${1/3}$Mn${1/3}$Co$_{1/3}$O$_2$ Cathodes: Deduced via XPS, DFT+DMFT, and Charge Transfer Multiplet Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Ruiwen Xie, Maximilian Mellin, Wolfram Jaegermann, Jan P. Hofmann, Frank M. F. de Groot, Hongbin Zhang
Understanding the evolution of the physicochemical bulk properties during the Li deintercalation (charging) process is critical for optimizing battery cathode materials. In this study, we combine X-ray photoelectron spectroscopy (XPS), density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations, and charge transfer multiplet (CTM) model simulations to investigate how hybridization between transition metal (TM) 3d and oxygen 2p orbitals evolves with Li deintercalation. Based on the presented approach combining theoretical calculations and experimental studies of pristine and deintercalated cathodes, two important problems of ion batteries can be addressed: i) the detailed electronic structure and involved changes with deintercalation providing information of the charge compensation mechanism, and ii) the precise experimental analysis of XPS data which are dominated by charge transfer coupled to final-state effects affecting the satellite structure. As main result for the investigated Li TM oxides, it can be concluded that the electron transfer coupled to the Li$ ^{+}$ -ion migration does not follow a rigid band model but is modified due to changes in TM 3d and O 2p states hybridization. Furthermore, this integrated approach identifies the 2p XPS satellite peak intensity of TM as an effective indicator of the redox chemistry. With that the redox chemistry of cathodes can be deduced, thus offering a foundation for designing more efficient battery materials.
Materials Science (cond-mat.mtrl-sci)
Numerical methods for quasi-stationary distributions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Sara Oliver-Bonafoux, Javier Aguilar, Tobias Galla, Raúl Toral
In stochastic processes with absorbing states, the quasi-stationary distribution provides valuable insights into the long-term behaviour prior to absorption. In this work, we revisit two well-established numerical methods for its computation. The first is an iterative algorithm for solving the non-linear equation that defines the quasi-stationary distribution. We generalise this technique to accommodate general Markov stochastic processes, either with discrete or continuous state space, and with multiple absorbing states. The second is a Monte Carlo method with resetting, for which we propose a novel single-trajectory approach that uses the trajectory’s own history to perform resets after absorption. In addition to these methodological contributions, we provide a detailed analysis of implementation aspects for both methods. We also compare their accuracy and efficiency across a range of examples. The results indicate that the iterative algorithm is generally the preferred choice for problems with simple boundaries, while the Monte Carlo approach is more suitable for problems with complex boundaries, where the implementation of the iterative algorithm is a challenging task.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
Subthermal Mean Transverse Energies Induced by Electron Refraction on the Jump in Mass at the Surface of Multialkali Photocathodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
S.A. Rozhkov, V.V. Bakin, H.E. Scheibler, V.S. Rusetsky, D.V. Gorshkov, D.A. Kustov, V.A. Golyashov, V.L. Alperovich, O. E. Tereshchenko
The search for photocathode materials with low mean transverse energies (MTEs) and, hence, low intrinsic emittance is of crucial importance for various fields of particle and solid state physics. Here, we demonstrate that polycrystalline multialkali Na$ _{2}$ KSb(Cs,Sb) photocathodes with negative effective electron affinity (NEA) have MTE values at room temperature by a factor of 2 lower than those of monocrystalline \textit{p}-GaAs(Cs,O) photocathodes. These low MTE values are due to the electron refraction on the jump in mass, between a small effective mass in Na$ _{2}$ KSb and free electron mass in vacuum. It is proved that, at the NEA state, up to half of photoelectrons are emitted in a narrow-angle cone with the fractional MTE of 9,meV at room temperature. We also showed that the transition from NEA to positive effective affinity results in the subthermal total MTE of the Na$ _{2}$ KSb(Cs,Sb) photocathode, along with quantum efficiency of about 10$ ^{-2}$ . The physical reasons for the manifestation of the refraction effect in multialkali photocathodes are discussed, opening up opportunities for the development of high-brightness and ultracold robust electron sources.
Materials Science (cond-mat.mtrl-sci)
6 pages, 3 figures
Highly-Linear Proximity-Based Bi-SQUID Operating above 4 K
New Submission | Superconductivity (cond-mat.supr-con) | 2025-10-06 20:00 EDT
G. Trupiano, E. Riccardi, C. Puglia, M. Kiczynski, A. Gardin, G. De Simoni, G. C. Tettamanzi, F. Giazotto
We demonstrate a highly linear superconducting quantum interference device (SQUID) amplifier based on a double-loop (Bi-SQUID) architecture incorporating three superconductor-normal metal-superconductor (S-N-S) junctions. Fabricated using niobium-gold technology, the device exhibits robust operation at liquid helium temperatures, with a superconducting transition temperature of 8.5 K. The flux-to-voltage transfer function demonstrates sharp, symmetric, and highly linear behavior at temperatures up to 5 K. Bi-SQUIDs featuring our single-element S-N-S design represent an interesting and original approach to this field, as they demonstrate a numerically estimated spurious-free dynamic range (SFDR) linearity exceeding 60 dB, achieved in a single element, simplifying the requirements in terms of arrays containing hundreds of junctions. These results highlight the potential of proximity-based Bi-SQUIDs for compact, low-noise, and highly linear cryogenic amplifiers in quantum sensing, magnetometry, and biomedical diagnostics.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Dissipation properties of anomalous Hall effect: intrinsic vs. extrinsic magnetic materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
V. Desbuis, D. Lacour, M. Hehn, S. Geiskopf, L. Michez, J. Rial, V. Baltz, J.-E. Wegrowe
A comparative study of anomalous-Hall current injection and anisotropic current injection (through planar Hall effect) are studied in Hall devices contacted to a lateral load circuit. Hall currents are injected into the load circuit from three different kinds of magnetic Hall bars: Mn5Si3 altermagnet, Co75Gd25 ferrimagnet, and Ni80Fe20 ferromagnet. The current, the voltage and the power are measured as a function of the load resistance and the Hall angle. It is observed that the power dissipated for the three kinds of materials fellow the same law as a function of load resistance and Hall angle, at the leading order in the Hall angle. Since the anomalous Hall effect in the altermagnetic Hall-bar is due to the intrinsic topological structure (i.e. due to the presence of a Berry phase in the reciprocal space), these observations suggest that the dissipative properties of anomalous Hall effect are dominated by the injection of electric charges accumulated at the edges (including electric screening), instead of the very mechanism responsible for it.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Percolation and criticality of systems with competing interactions on Bethe lattices: limitations and potential strengths of cluster schemes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Greivin Alfaro Miranda, Mingyuan Zheng, Patrick Charbonneau, Antonio Coniglio, Leticia F. Cugliandolo, Marco Tarzia
The random clusters introduced by Fortuin and Kasteleyn (FK) and analyzed by Coniglio and Klein (CK) for Ising and related models have led first Swendsen and Wang and then Wolff to formulate remarkably efficient Markov chain Monte Carlo sampling schemes that weaken the critical slowing down. In frustrated models, however, no standard way to produce a comparable gain at small frustration – let alone efficiently sample the large frustration regime – has yet been identified. In order to understand why formulating appropriate cluster criteria for frustrated models has thus far been elusive, we here study minimal short-range attractive and long-range repulsive as well as spin-glass models on Bethe lattices. Using a generalization of the CK approach and the cavity-field method, the appropriateness and limitations of the FK–CK type clusters are identified. We find that a standard, constructive cluster scheme is then inoperable, and that the frustration range over which generalized FK–CK clusters are even definable is finite. These results demonstrate the futility of seeking constructive cluster schemes for frustrated systems but leaves open the possibility that alternate approaches could be devised.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
31 pages, 13 figures
Deconstruction of the anisotropic magnetic interactions from spin-entangled optical excitations in van der Waals antiferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Dipankar Jana, Swagata Acharya, Milan Orlita, Clement Faugeras, Dimitar Pashov, Mark van Schilfgaarde, Marek Potemski, Maciej Koperski
Magneto-optical excitations in antiferromagnetic d systems can originate from a multiplicity of light-spin and spin-spin interactions, as the light and spin degrees of freedom can be entangled. This is exemplified in van der Waals systems with attendant strong anisotropy between in-plane and out- of-plane directions, such as MnPS3 and NiPS3 films studied here. The rich interplay between the magnetic ordering and sub-bandgap optical transitions poses a challenge to resolve the mechanisms driving spin-entangled optical transitions, as well as the single-particle bandgap itself. Here we employ a high-fidelity ab initio theory to find a realistic estimation of the bandgap by elucidating the atom- and orbital-resolved contributions to the fundamental sub-bands. We further demonstrate that the spin-entangled excitations, observable as photoluminescence and absorption resonances, originate from an on-site spin-flip transition confined to a magnetic atom (Mn or Ni). The evolution of the spin-flip transition
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages 4 figures
Modeling Quantum Geometry for Fractional Chern Insulators with unsupervised learning
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-10-06 20:00 EDT
Ang-Kun Wu, Louis Primeau, Jingtao Zhang, Kai Sun, Yang Zhang, Shi-Zeng Lin
Fractional Chern insulators (FCIs) in moire materials present a unique platform for exploring strongly correlated topological phases beyond the paradigm of ideal quantum geometry. While analytical approaches to FCIs and fractional quantum Hall states (FQHS) often rely on idealized Bloch wavefunctions, realistic moire models lack direct tunability of quantum metric and Berry curvature, limiting theoretical and numerical exploration. Here, we introduce an unsupervised machine learning framework to model interacting Hamiltonians directly through the distribution of single-particle form factors. Using a variational autoencoder (VAE), we show that unsupervised learning can not only distinguish FCI and non-FCI states, but also generate new form factors with distinct topological character, not present in the training set. This latent space enables the generation and interpolation of form factors for topological flatbands with Chern number $ |C|=1$ , enabling the discovery of unobserved many-body states such as charge density waves. Principal component analysis (PCA) further reveals that the dominant patterns in the form factors-reflecting correlations across the Brillouin zone-can be decomposed into components with approximately quantized Chern numbers, providing new insights into the global and topological structure of quantum geometry. Our results highlight the ability of machine learning to generalize and model topological quantum systems, paving the way for the inverse design of form factors with tailored quantum geometry and many-body phases in flatband materials.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn)
17 pages, 11 figures
Structural Chirality and Natural Optical Activity across the $α$-to-$β$ Phase Transition in SiO$_2$ and AlPO$_4$ from first-principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
F. Gómez-Ortiz, A. Zabalo, A. M. Glazer, E. E. McCabe, A. H. Romero, E. Bousquet
Natural optical activity (NOA), the ability of a material to rotate the plane of polarized light, has traditionally been associated with structural chirality. However, this relationship has often been oversimplified, leading to conceptual misunderstandings, particularly when attempts are made to directly correlate structural handedness with optical rotatory power. In reality, the relationship between chirality and NOA is more nuanced: optical activity can arise in both chiral and achiral crystal structures, and the sign of the rotation cannot necessarily be inferred from the handedness of the space group. %
In this work, we conduct a first-principles investigation of natural optical activity in SiO$ _2$ and AlPO$ _4$ crystals, focusing on their enantiomorphic structural phase transition from high-symmetry hexagonal ($ P6_422$ or $ P6_222$ ) to low-symmetry trigonal ($ P3_121$ or $ P3_221$ ) space groups. This transition, driven by the condensation of a zone-center $ \Gamma_3$ phonon mode, reverses the screw axis type given by the space group symbol while leaving the sign of the optical activity unchanged. By following the evolution of the structure and the optical response along the transition pathway, we clarify the microscopic origin of this behavior. We demonstrate that the sense of optical rotation is determined not by the nominal helicity of the screw axis given in the space group symbol, but by the atomic-scale helicity of the most polarizable atoms of the structure.
Materials Science (cond-mat.mtrl-sci)
Electrically modulated light-emitting diodes driven by resonant and antiresonant tunneling between Cr$_2$Ge$_2$Te$_6$ electrodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Natalia Zawadzka, Kristina Vaklinova, Tomasz Woźniak, Mihai I. Sturza, Holger Kohlmann, Kenji Watanabe, Takashi Taniguchi, Adam Babiński, Maciej Koperski, Maciej R. Molas
Exploring the electron tunneling mechanisms in diverse materials systems constitutes a versatile strategy for tailoring the properties of optoelectronic devices. In this domain, bipolar vertical tunneling junctions composed of van der Waals materials with vastly different electronic band structures enable simultaneous injection of electrons and holes into an optically active material, providing a universal blueprint for light-emitting diodes (LEDs). Efficient modulation of the injection efficiency has previously been demonstrated by creating resonant states within the energy barrier formed by the luminescent material. Here, we present an alternative approach towards resonant tunneling conditions by fabricating tunneling junctions composed entirely from gapped materials: Cr$ _2$ Ge$ _2$ Te$ _6$ as electrodes, hBN as a tunneling barrier, and monolayer WSe$ _2$ as a luminescent medium. The characterization of such LEDs revealed a nonmonotonous evolution of the electroluminescence intensity with the tunneling bias. The dominant role driving the characteristics of the electron tunneling was associated with the relative alignment of the density of states in Cr$ _2$ Ge$ _2$ Te$ _6$ electrodes. The unique device architecture introduced here presents a universal pathway towards LEDs operating at room temperature with electrically modulated emission intensity.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 4 figures + SI
Rogue waves in extended Gross-Pitaevskii Models with a Lee-Huang-Yang correction
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-10-06 20:00 EDT
Sathyanarayanan Chandramouli, Simeon I. Mistakidis, Garyfallia C. Katsimiga, Daniel J. Ratliff, Dimitrios J. Frantzeskakis, Panayotis G. Kevrekidis
We explore the existence and dynamical generation of rogue waves (RWs) within a one dimensional quantum droplet bearing environment. RWs are computed by deploying a spacetime fixed point scheme to the relevant extended Gross Pitaevskii equation (eGPE). Parametric regions where the ensuing RWs are different from their counterparts in the nonlinear Schroedinger equation are identified. To corroborate the controllable generation, relevant to ultracold atom experiments, of these rogue patterns we exploit two different protocols. The first is based on interfering dam break flows emanating from Riemann initial conditions and the second refers to the gradient catastrophe of a spatially localized waveform. A multitude of possible RWs are found in this system, spanning waveforms reminiscent of the Peregrine soliton, its spatially periodic variants, namely, the Akhmediev breathers, and other higher order RW solutions of the nonlinear Schroedinger equation. Key elements of the shape of the corresponding eGPE RWs traced back to nonintegrability and the presence of competing interactions are discussed. Our results set the stage for probing a multitude of unexplored rogue like waveforms in such mixtures with competing interactions and should be accessible to current ultracold atom experiments.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
13 pages, 7 figures, 1 Appendix
The systemic impact of edges in financial networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Michel Alexandre, Thiago Christiano Silva, Francisco A. Rodrigues
In this paper, we assess how the stability of financial networks is affected by interconnectedness considering its tiniest variation: the edge. We compute the impact of edges as the percentage difference in the systemic risk (SR) of the whole network caused by the inclusion of that edge. We apply this framework to a thorough Brazilian dataset to compute the impact of bank-firm edges. After observing that (i) edges are heterogeneous regarding their impact on the SR, and (ii) the fraction of edges whose impact on the SR is non-positive increases with the level of the initial shock, we use machine learning techniques to try to predict two variables: the criticality of the edges (defining as critical an edge whose impact on SR is significantly greater than that of the others) and the sign of the edge impact. The level of accuracy obtained in these prediction exercises was very high. These results have important implications for the development macroprudential policies aimed at financial stability. Our framework allows to identify, based on features related to the origin and destination nodes of the edge (i.e., the lending bank and the borrowing firm), whether an additional loan will have a significant and positive impact on the SR.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
28 pages, 11 figures
Thermal assisted transport of biexcitons in monolayer WSe2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Dorian Béret, Louka Hemmen, Vishwas Jindal, Sreyan Raha, Thierry Amand, Delphine Lagarde, Andrea Balocchi, Cédric Robert, Helene Carrere, Xavier Marie, Pierre Renucci, Laurent Lombez
Studies of excitonic transport in transition metal dichalcogenide monolayers have attracted increasing interest in recent years in order to develop nano-optoelectronic devices made with 2D materials. These studies began with low to moderate optical excitation regimes, and more recently have focused on high injection regimes where nonlinear effects appear. This article is focused on the transport of biexcitons by spatially and temporally resolved photoluminescence spectroscopy at high excitation flux. The study is carried out on a high-quality WSe$ _2$ monolayer encapsulated in hexagonal boron nitride. The results show that a Seebeck current affects transport in connection with the presence of hot biexcitons. In particular, we observe the formation of spatial rings, also called halos, which have been observed in other excitonic gases. These results tend to generalize the importance of high-energy populations in excitonic transport in TMD, even for complex and heavy excitonic particles.
Materials Science (cond-mat.mtrl-sci)
Polarization dependence of spin-electric transitions in molecular exchange qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Filippo Troiani, Athanassios K. Boudalis
Quasi-optical experiments are emerging as a powerful technique to probe magnetic transitions in molecular spin systems. However, the simultaneous presence of the electric- and magnetic-dipole induced transitions poses the challenge of discriminating between these two contributions. Besides, the identification of the spin-electric transitions can hardly rely on the peak intensity, because of the current uncertainties on the value of the spin-electric coupling in most molecular compounds. Here, we compute the polarizations required for electric- and magnetic-dipole induced transitions through spin-Hamiltonian models of molecular spin triangles. We show that the polarization allows a clear discrimination between the two kinds of transitions. In addition, it allows one to identify the physical origin of the zero-field splitting in the ground multiplet, a debated issue with significant implications on the coherence properties of the spin qubit implemented in molecular spin triangles.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Analytical solution of a free-fermion chain with time-dependent ramps
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Viktor Eisler, Riccarda Bonsignori, Stefano Scopa
We provide an exact analytical solution of the single-particle Schrödinger equation for a chain of non-interacting fermions subject to a time-dependent linear potential, with its slope varied as an arbitrary function of time. The resulting dynamics exhibit self-similar behavior, with a structure reminiscent of the domain wall melting problem, albeit characterized by a nontrivial time-dependent length scale and phase. Building on this solution, we derive hydrodynamic predictions for the evolution of particle density, current, and entanglement entropy along the chain. In the special case of a sudden quench, the system develops a breathing interface region, which may be interpreted as a realization of Wannier-Stark localization, as previously suggested on the basis of hydrodynamic arguments.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
8 pages, 6 figures
Spatial uniformity of g-tensor and spin-orbit interaction in germanium hole spin qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-10-06 20:00 EDT
Inga Seidler, Bence Hetényi, Lisa Sommer, Leonardo Massai, Konstantinos Tsoukalas, Eoin G. Kelly, Alexei Orekhov, Michele Aldeghi, Stephen W. Bedell, Stephan Paredes, Felix J. Schupp, Matthias Mergenthaler, Gian Salis, Andreas Fuhrer, Patrick Harvey-Collard
Holes in Ge/SiGe heterostructures are now a leading platform for semiconductor spin qubits, thanks to the high confinement quality, two-dimensional arrays, high tunability, and larger gate structure dimensions. One limiting factor for the operation of large arrays of qubits is the considerable variation in qubit frequencies or properties resulting from the strongly anisotropic $ g$ -tensor. We study the $ g$ -tensors of six and seven qubits in an array with a Y geometry across two devices. We report a mean distribution of the tilts of the $ g$ -tensor’s out-of-plane principal axis of around $ 1.1 °$ , where nearby quantum dots are more likely to have a similar tilt. Independently of this tilt, and unlike simple theoretical predictions, we find a strong in-plane $ g$ -tensor anisotropy with strong correlations between neighboring quantum dots. Additionally, in one device where the principal axes of all g-tensors are aligned along the [100] crystal direction, we extract the spin-flip tunneling vector from adjacent dot pairs and find a pattern that is consistent with a uniform Dresselhaus-like spin-orbit field. The Y arrangement of the gate layout and quantum dots allows us to rule out local factors like electrostatic confinement shape or local strain as the origin of the preferential direction. Our results reveal long-range correlations in the spin-orbit interaction and $ g$ -tensors that were not previously predicted or observed, and could prove critical to reliably understand $ g$ -tensors in germanium quantum dots.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Minimal-Dissipation Learning for Energy-Based Models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
We show that the bias of the approximate maximum-likelihood estimation (MLE) objective of a persistent chain energy-based model (EBM) is precisely equal to the thermodynamic excess work of an overdamped Langevin dynamical system. We then answer the question of whether such a model can be trained with minimal excess work, that is, energy dissipation, in a finite amount of time. We find that a Gaussian energy function with constant variance can be trained with minimal excess work by controlling only the learning rate. This proves that it is possible to train a persistent chain EBM in a finite amount of time with minimal dissipation and also provides a lower bound on the energy required for the computation. We refer to such a learning process that minimizes the excess work as minimal-dissipation learning. We then provide a generalization of the optimal learning rate schedule to general potentials and find that it induces a natural gradient flow on the MLE objective, a well-known second-order optimization method.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
Heterogenous Dynamics in a Polymer Solution Revealed through Measurement of Ultraslow Convection
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-10-06 20:00 EDT
Thomas P. Chaney, Samuel D. Marks, Dylan M. Ladd, Andrei Fluerasu, Federico Zontone, Yuriy Chushkin, Sebastian Frücht, Dina Sheyfer, Kelsey Levine, Amnahir E. Peña-Alcántara, Hans-Georg Steinrück, Michael F. Toney
Understanding solution-phase aggregation and dynamics in complex fluids is critical for material processing, yet widely used dynamic light scattering (DLS) fails for strongly attenuating systems such as conjugated polymers. We use X-ray photon correlation spectroscopy (XPCS) to probe the dynamics of a polymer, PM7, in toluene, revealing unexpected oscillations in the autocorrelation function that show vertical flow during measurement. Despite the relatively low X-ray absorption, measured flow velocities scale with X-ray beam power and suggest convective transport. Our analyses reveal both mobile and static scatterers that together produce oscillatory, heterodyne features in the measured correlation functions. Finite element simulations predict flow velocities much larger than observed, suggesting that entanglements of the aggregates slow their motion. These results provide a direct measurement of ultra-slow convection and highlight the need to explicitly account for even modest beam heating in interpreting XPCS results. Moreover, the observation of distinct scatterer populations underscores the structural complexity of conjugated polymer solutions.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Slow dynamics from a nested hierarchy of frozen states
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-10-06 20:00 EDT
Vanja Marić, Luka Paljk, Lenart Zadnik
We identify the mechanism of slow heterogeneous relaxation in quantum kinetically constrained models (KCMs) in which the potential energy strength is controlled by a coupling parameter. The regime of slow relaxation includes the large-coupling limit. By expanding around that limit, we reveal a \emph{nested hierarchy} of states that remain frozen on time scales determined by powers of the coupling. The classification of such states, together with the evolution of their Krylov complexity, reveal that these time scales are related to the distance between the sites where facilitated dynamics is allowed by the kinetic constraint. While correlations within frozen states relax slowly and exhibit metastable plateaus that persist on time scales set by powers of the coupling parameter, the correlations in the rest of the states decay rapidly. We compute the plateau heights of correlations across all frozen states up to second-order corrections in the inverse coupling. Our results explain slow relaxation in quantum KCMs and elucidate dynamical heterogeneity by relating the relaxation times to the spatial separations between the active regions.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
10 pages, 5 figures
Nonsymmorphic symmetry protected hourglass Dirac chain topology and conventional superconductivity in ZrIrGe
New Submission | Superconductivity (cond-mat.supr-con) | 2025-10-06 20:00 EDT
Pavan Kumar Meena, Dibyendu Samanta, Shashank Srivastava, Poulami Manna, Sudeep Kumar Ghosh, Ravi Prakash Singh
Ternary transition-metal germanide superconductors with nonsymmorphic symmetries offer promising platforms for symmetry-protected topological phases. In this work, we investigate ZrIrGe, which crystallizes in the nonsymmorphic TiNiSi-type structure. Electrical, magnetic, and specific heat measurements confirm bulk type-II superconductivity with a full gap and a transition temperature of 2.84(7) K, consistent with weak-coupling BCS behavior. First-principles calculations reveal hourglass-shaped bulk band dispersions and a Dirac chain composed of symmetry-protected fourfold-degenerate Dirac points, leading to drumhead-like surface states near the Fermi level. Additionally, ZrIrGe exhibits a nontrivial $ \mathbb{Z}_2$ topological character, resulting in helical surface states that cross the Fermi level, making it a strong candidate for proximity-induced topological superconductivity. The coexistence of conventional superconductivity and topological band features establishes ZrIrGe as a rare stoichiometric system for exploring intrinsic topological superconductivity.
Superconductivity (cond-mat.supr-con)
9 pages, 4 figures, Accepted in Physical Review B
Sliding multiferroicity in hexagonal stacked CrI3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-10-06 20:00 EDT
Carter Fox, Jose D. Mella, Jack Rollins, Yangchen He, Yulu Mao, Haotian Jiang, Alaina Drew, Hongrui Ma, Takashi Taniguchi, Kenji Watanabe, Ying Wang, Daniel Rhodes, Salvador Barraza-Lopez, Jun Xiao
Developing new multiferroics at the two-dimensional (2D) limit with energy-efficient magnetoelectric coupling can inform the interplay physics of novel orders and advance on-chip high-performance computing applications. Here we apply stacking order engineering to create a new type of 2D multiferroics, namely sliding multiferroics, based on polar hexagonal stacked (H-stacked) CrI3. This new stacking order removes structural inversion symmetry and gives rise to room temperature sliding ferroelectricity, as confirmed by Raman spectroscopy, second harmonic generation spectroscopy and electrical transport measurements. Building upon the gate-dependent reflective magnetic circular dichroism, first-principles calculations, and modeling, sliding ferroelectricity is shown to interplay with an emergent interfacial ferromagnetism via interlayer spin-polarized charge transfer. This coupling mechanism results in non-volatile magnetic switching by as low as 0.4V across the H-stacked CrI3. Our demonstration introduces polar stacking order engineering of 2D magnets as a general approach to create non-volatile 2D multiferroics with efficient magnetoelectric coupling, paving the way for low-power electronics and spintronics at the atomically thin limit.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)