CMP Journal 2026-04-20
Statistics
Nature Materials: 1
Nature Physics: 2
Nature Reviews Materials: 1
arXiv: 63
Nature Materials
Sub-wavelength extreme ultraviolet microscopy reveals domain-wall stability during ultrafast demagnetization
Original Paper | Imaging techniques | 2026-04-19 20:00 EDT
Hung-Tzu Chang, Sergey Zayko, Timo Schmidt, Ofer Kfir, Murat Sivis, Johan H. Mentink, Manfred Albrecht, Claus Ropers
Ultrafast control of magnetic textures relies on understanding how domain walls respond to femtosecond laser excitation. Previous X-ray scattering studies suggested transient domain-wall broadening and motion during reversible demagnetization. Yet such dynamics have never been observed directly, owing to insufficient spatiotemporal resolution in existing techniques. Here we introduce femtosecond extreme ultraviolet microscopy with sub-wavelength 13.5-nm spatial resolution, enabling direct real-space imaging of domains in ferri- and ferromagnetic thin films during laser-induced demagnetization. Within an experimental precision better than 2 nm, domain-wall positions and widths remain unchanged up to the onset of irreversible magnetic switching at 50%-80% demagnetization. These findings establish quantitative limits for reversible domain-wall motion and spin transport upon ultrafast demagnetization, while implying that irreversible reconfiguration underlies characteristic changes in diffraction signatures at high fluence. The approach expands time-resolved microscopy into the nanometre and femtosecond regime, enabling element-specific studies of coupled spin, charge and lattice dynamics in quantum and functional materials.
Imaging techniques, Magnetic properties and materials, Surfaces, interfaces and thin films, Ultrafast photonics
Nature Physics
Average topological phase in a disordered Rydberg atom array
Original Paper | Quantum simulation | 2026-04-19 20:00 EDT
Zongpei Yue, Yu-Feng Mao, Xinhui Liang, Zhen-Xing Hua, Peiyun Ge, Yu-Xin Chao, Kai Li, Chen Jia, Meng Khoon Tey, Yong Xu, Li You
Topological phases have been widely studied in quantum pure states, where exact symmetries protect them. Such symmetry-protected topological phases have been observed in a range of systems, from solid-state materials to synthetic quantum platforms. Recent theory predicts that average symmetry-protected topological phases can also emerge in mixed quantum states that arise in realistic settings with decoherence or disorder, but experiments have not yet established them. Here we report observations of a disorder-induced many-body interacting average symmetry-protected topological phase in an atom array. We introduce structural disorder by applying random offsets to the tweezer positions that define the lattice, which generates fluctuating long-range dipolar interactions between confined atoms. Spatially resolved atom-atom correlation functions for different dimer configurations characterize the resulting induced topological phase. We detect ground-state degeneracy across disordered configurations and compare it directly with the ordered case. Finally, by probing the quench dynamics of a highly excited state, we observe slower decay of edge spin magnetization than in the bulk, consistent with topologically protected edge modes in the disordered lattice.
Quantum simulation, Topological matter, Ultracold gases
Transverse optical torque observed at the nanoscale
Original Paper | Characterization and analytical techniques | 2026-04-19 20:00 EDT
Ryoma Fukuhara, Tsutomu Shimura, Yoshito Y. Tanaka
Optical forces and torques acting on resonant nanostructures smaller than the wavelength of light have attracted interest in nanoscience and nanotechnology. However, experimental characterization at the nanoscale remains challenging due to the diffraction limit of light. Here we present an approach for the three-dimensional measurement of nanoscale optical forces and torques. This is achieved through the optical trapping and precision spatial tracking of a designed microscale structure that contains embedded target nanostructures. Our method enables the confinement and measurement of nanostructure positions and orientations across three translational and three rotational degrees of freedom, independent of the size, shape and material of the nanostructure. Using this method, we observe transverse optical torque on plasmon-resonant nanostructures and reveal that this behaviour is governed by the optical helicity rather than the angular momentum of incident light. This versatile platform advances our fundamental understanding of nano-optomechanical interactions and opens up possibilities for precise optical manipulation and nanoactuator design.
Characterization and analytical techniques, Nanophotonics and plasmonics, Optical manipulation and tweezers, Optical metrology
Nature Reviews Materials
Inverse design for scalable photonic systems
Review Paper | Applied optics | 2026-04-19 20:00 EDT
Louise Schul, Sydney Mason, Sungjun Eun, Geun Ho Ahn, Jelena Vučković
Over the past two decades, photonic inverse design has emerged as a powerful approach to implement photonic devices with improved performance or to realize new functionalities. Whereas the efforts over the first decade focused on proof-of-concept devices designed and fabricated in university laboratories, the focus over the past 5-10 years has shifted towards implementation of scalable photonic systems. This Review surveys this recent progress and the challenges and new directions in photonics inverse design. We focus on large-scale 3D photonic inverse design, including metasurfaces, on the translation of inverse design to commercial foundries and practical silicon photonics, on the application of photonic inverse design to different materials systems, wavelengths and optical effects and, finally, on new directions such as inverse design of quantum systems.
Applied optics, Integrated optics, Nanophotonics and plasmonics, Optical materials and structures
arXiv
Exascale Multi-Task Graph Foundation Models for Imbalanced, Multi-Fidelity Atomistic Data
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Massimiliano Lupo Pasini, Jong Youl Choi, Kshitij Mehta, Richard Messerly, Rylie Weaver, Linda Ungerboeck, Isaac Lyngaas, Benajmin Stump, Ashwin M. Aji, Karl W. Schulz, Jorda Polo
We present an exascale workflow for materials discovery using atomistic graph foundation models built on HydraGNN. We jointly train on 16 open first-principles datasets (544+ million structures covering 85+ elements) using a multi-task architecture with per-dataset heads and a scalable ADIOS2/DDStore data pipeline. On Frontier, we execute six large-scale DeepHyper hyperparameter optimization campaigns in FP64 and promote the top-performing message-passing models to sustained 2,048-node training, yielding a PaiNN-based lead model. The resulting model enables billion-scale screening, evaluating 1.1 billion atomistic structures in 50 seconds, compressing a workload that would require years of first-principles computation, and supports data-scarce fine-tuning across diverse downstream tasks. We quantify precision-performance tradeoffs (BF16/FP32/FP64), demonstrate transfer across twelve chemically diverse downstream tasks, and establish seamless strong- and weak-scaling across Frontier, Aurora, and Perlmutter. This work allows fast and reliable exploration of vast chemical design spaces that are otherwise inaccessible to first-principles methods.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
12 pages; 5 figures; 15 tables
Atomic-scale order enables high thermal boundary conductance at $β$-Ga$_2$O$_3$/4H-SiC interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Hongao Yang, Yongtao Yang, Yuanbin Liu, Tao Ding, Yang Shen, Jiawei Huang, Weigang Ma, Linfeng Fei, Zhenping Wu, Gábor Csányi, Bingyang Cao
Thermal boundary conductance (TBC) at dissimilar interfaces imposes a fundamental limit on electronic device performance, yet predicting and understanding heat transport across realistic, disordered boundaries remains elusive. Here, we develop a computational framework that combines machine-learned interatomic potentials with lattice dynamics to address the long-standing problem of how interfacial structure, from disordered to atomically sharp, affects thermal transport in the technologically important $ \beta$ -Ga$ _2$ O$ _3$ /4H-SiC heterostructure. By explicitly accounting for phonon wave-particle duality, we show that interfacial disorder introduces additional interfacial phonon modes that facilitate vibrational impedance matching between the two highly dissimilar crystals, yet it simultaneously disrupts interfacial phonon coherence and limits the potential heat-transport benefit. Our atomistic simulations further indicate that restoring atomic-scale order preserves coherence and yields markedly higher conductance. These insights motivate the controlled epitaxial growth of $ \beta$ -Ga$ _2$ O$ _3$ /4H-SiC heterostructures with systematically tuned interfacial order. Experimental measurements validate our predictions, achieving a record-high TBC of 231 MW m$ ^{-2}$ K$ ^{-1}$ at atomically sharp junctions. Beyond the immediate implications for $ \beta$ -Ga$ _2$ O$ _3$ -based power electronics, our results establish the preservation of interfacial phonon coherence as an effective strategy for mitigating thermal bottlenecks in mismatched systems.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Ultrastrong Coupling Signatures in Photon Statistics from Terahertz Higgs-Polaritons
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Spenser Talkington, Benjamin Kass, Martin Claassen
The ultrastrong coupling regime of cavity photons and quantum materials has emerged as a pathway to modify materials properties, however definitive signatures of ultrastrong coupling remain elusive. Focusing on the quantum photon statistics of light transmitted through a cavity-embedded superconductor, we show that a two-photon Higgs polariton at strong coupling realizes a photonic nonlinearity at the single terahertz photon level. We find that as light-matter coupling increases, the photon statistics show pronounced changes due to the formation of a hybrid photon-matter dark-cavity state with finite photon occupancy, producing testable signatures of ultrastrong coupling. We derive a non-Markovian input output relation and study the cavity-embedded superconductor 2H-NbSe2 as it approaches ultrastrong light-matter coupling. Our results reveal a diagnostic for ultrastrong coupling in the two-photon coincidence statistics that is absent in total counts.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con), Optics (physics.optics), Quantum Physics (quant-ph)
5+18 pages, 3+11 figures
Singlet-only always-on gapless exchange (SAGE) spin qubits: Charge noise effects and two-qubit gates
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Nathan L. Foulk, Katharina Laubscher, Silas Hoffman, Sankar Das Sarma
Singlet-only always-on gapless exchange (SAGE) spin qubits are an alternative type of exchange-only (EO) qubits that encode a single qubit in the spins of four electrons located in four tunnel-coupled quantum dots. While conventional EO qubits are susceptible to local magnetic field gradients caused by local nuclear environments and $ g$ -factor variations, the SAGE qubit subspace is inherently protected from magnetic-gradient-induced Pauli errors by virtue of the singlet-only encoding, which is invariant under magnetic field gradients, and the always-on exchange couplings, which provide energetic leakage protection. However, the always-on operation simultaneously increases the qubit’s sensitivity to charge noise. Here, starting from a Hubbard model describing the underlying electronic structure of the coupled quantum dots, we characterize the performance of SAGE qubits in the presence of $ 1/f$ charge noise that induces fluctuations in both the dot chemical potentials and the interdot tunnel couplings. We calculate SAGE idle coherence times and show that realistic CPMG-like pulse sequences can be used to significantly extend SAGE single-qubit coherence times for experimentally relevant charge noise strengths. We likewise study the fidelity of SAGE two-qubit gates in the presence of charge and magnetic noise and again propose a simple refocusing strategy to mitigate the noise, while increased ramp times of the entangling pulse suppress leakage into noncomputational states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
The Phase Transitions in a $p$ spin Glass Model: A Numerical Study
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-04-20 20:00 EDT
Prerak Gupta, Auditya Sharma, Bharadwaj Vedula, J. Yeo, M.A. Moore
We investigate the balanced $ M=4$ , $ p=4$ spin-glass model for a one-dimensional long-range proxy for the finite dimensional short-range $ p$ -spin glass model to examine the nature of the glass transition beyond mean-field theory. We perform large-scale Monte Carlo equilibrated simulations for both fully connected and power-law diluted versions of the model. The critical temperatures extracted from the finite-size scaling (FSS) analysis of spin-glass susceptibility are in good agreement with theoretical predictions for $ \sigma = 0, 0.25$ , and 0.55. For these values of the long-range exponent $ \sigma$ (which is the power of the decrease of the interactions between the spins with their separation), one might have expected that mean-field theory would provide a good description of the system. However, the spin-overlap distribution and the value of the $ \lambda$ -parameter do not provide numerical evidence for a one-step replica symmetry breaking (1RSB) phase transition. Instead, our results indicate a direct transition from the paramagnetic state to a full replica symmetry broken phase, with a renormalized value of $ \lambda\equiv \omega_2/\omega_1 < 1$ suggesting a continuous FRSB transition, despite this ratio being equal to 2 at mean-field level. A value of $ \lambda > 1$ is required for the discontinuous 1RSB transition. We argue that strong finite-size effects and closely spaced transition temperatures remove the expected 1RSB transition for the system sizes which we can study. For values of the exponent $ \sigma = 0.85$ , which roughly corresponds to a three dimensional system, we find that the renormalized value of $ \lambda$ is again less than 1, with no signs of either the 1RSB transition or the continuous FRSB transition, suggesting that the Kauzmann temperature $ T_K$ in three dimensions might be zero and the complete absence of phase transitions in structural glasses.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
22 pages, 16 figures, 2 tables
Simulating altermagnets using mumax+
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Lars Moreels, Nicolai Bechler, Bartel Van Waeyenberge, Jonathan Leliaert, Jan Masell
In this paper, we demonstrate how altermagnets can be simulated in the recently released micromagnetic simulation package mumax+. We have added a new magnet class for d-wave altermagnets and demonstrate how mumax+ is able to reproduce the analytical solutions for line profiles of the Néel vector and net magnetization for a Bloch domain wall. Next, we show simulation results of the magnon dispersion relation and its dependence on the anisotropic nature of the exchange interaction. Finally, we study the motion of a Néel skyrmion by applying a spin transfer torque. This new feature was implemented by extending the pre-existing code base for antiferromagnetic simulations. The object-oriented design of mumax+ allows for a correct calculation of the magnetostatic field in multi-sublattice systems, a feature that many other micromagnetic simulators lack.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Divergence of detachment forces in the finite Voronoi model
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Detachment and fracture are central to many tissue-level processes, but they are challenging to simulate with Voronoi-type models that typically assume a confluent tissue. Here we analyze the finite Voronoi model, a nonconfluent extension of conventional Voronoi models, in which cell boundaries are composed of straight Voronoi edges and circular arcs of fixed radius $ \ell$ . When the line tension on cell-medium interfaces exceeds the tension on cell-cell contacts, we find that the model exhibits a strong time-step dependence in the fracture timescale of initially intact active clusters: decreasing $ \Delta t$ can unphysically suppress cluster rupture events. We trace this behavior to a divergence of detachment forces in the finite Voronoi model and introduce a simple regularization. Finally, we calibrate the near-detachment mechanics against a deformable polygon model and examine how key physical parameters control the tissue fracture timescale under two different calibration strategies. Our results show that, for studies focused on fracture or intercellular adhesion in nonconfluent monolayers, a physically motivated calibration of near-detachment mechanics in the finite Voronoi model is essential.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Quantitative Methods (q-bio.QM)
11 pages, 7 figures, 1 table
Device-area selection of memristive transport regimes in epitaxial $Hf_{0.5}Zr_{0.5}O_{2}$-based ferroelectric devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Priscila A. Tapia Presas, Lautaro Galarregui, Wilson Román Acevedo, Myriam H. Aguirre, José Santiso, Sylvia Matzen, Beatriz Noheda, Diego Rubi
Ferroelectric memristive devices based on hafnia are promising systems for neuromorphic electronics, yet the interplay between polarization-modulated resistive changes and defect-mediated transport often leads to complex and debated switching mechanisms. Here, we investigate this competition in epitaxial Hf$ _{0.5}$ Zr$ _{0.5}$ O$ _2$ /La$ _{0.67}$ Sr$ _{0.33}$ MnO$ _3$ heterostructures with Pt top electrodes by combining structural, ferroelectric, and memristive characterization with a statistical analysis across a broad range of device areas spanning three orders of magnitude. We identify two distinct memristive regimes with opposite resistance–voltage chiralities. Small devices exhibit a low-resistance state that scales inversely with area, consistent with area-distributed tunneling transport, while larger devices display an area-independent resistance indicative of localized conductive channels. A statistical nucleation model quantitatively captures this behavior and yields a crossover characteristic area $ A^\ast \approx 10^3~\mu\mathrm{m}^2$ . This crossover also correlates with the onset of ferroelectric wake-up in larger devices, linking conductive-channel nucleation and oxygen-vacancy redistribution within a unified physical picture. These results establish lateral device size as a key parameter controlling the dominant transport mechanism in epitaxial hafnia-based devices.
Materials Science (cond-mat.mtrl-sci)
17 pages, 4 figures
Electronic Signature of Melting Onset in Polycrystalline Copper at Extreme Conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Edna R. Toro, Tobias Held, Armin Bergermann, Megan Ikeya, Maximilian Maigler, Eric R. Sung, Dirk O. Gericke, Mianzhen Mo, Baerbel Rethfeld, Siegfried H. Glenzer, Benjamin K. Ofori-Okai
Ultrafast melting is fundamentally a structural transition of the ionic lattice, but this rearrangement also reshapes the electronic properties by changing the energy landscape and scattering mechanisms. Although the electrons react almost instantaneously, it is not {\it a priori} clear how much lattice disorder is required for a significant response. Here, we show that the onset of melting already produces a clear electronic signature in polycrystalline copper. Using single-shot terahertz time-domain spectroscopy on thin films excited over a wide range of laser fluences, we infer the transient conductivity during the first picoseconds after excitation. The data, supported by two-temperature molecular-dynamics simulations, show that before melting, electron transport is substantially limited by grain-boundary scattering and that melting strongly suppresses this channel. As melting begins at these interfaces, we observe a transient increase in the conductivity that directly marks the onset of the phase transition. More broadly, these results show that ionic and electronic relaxation stages are closely coupled in nonequilibrium laser-driven matter and that optical measurements can resolve distinct stages of melting.
Materials Science (cond-mat.mtrl-sci)
Formation of cylindrical shells via sphere packing from fluidized beds
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Vinícius Pereira da Silva Oliveira, Danilo da Silva Borges, Erick de Moraes Franklin, Jorge Manuel Peixinho
The results of a numerical investigation of fluidized beds of spherical particles in a narrow vertical cylindrical pipe, with particular attention to the spontaneous settling along the wall, are reported. Starting from a steady fluidized state, the particles fluctuate because of fluid-particle, particle-particle, and particle-wall interactions. The particles are heavier than the fluid, with diameters d yielding ratios of pipe to particle diameters D/d=4.3 and 4.7. For given ranges of flow velocities and bed sizes, particles settle on the wall, with a decrease in the bed height and particle fluctuations. Either a glass- or crystal-like shell forms along the pipe wall, in qualitative agreement with previous experiments. The polydispersity and the particle-particle friction are varied to test the stability of the particulate shell formation. The shell structure is analyzed by unwrapping it in a plane and locating all particles and their contact points, and we find that it exhibits a hexagonal lattice with a defects density that increases with polydispersity. The shell formation is hindered by polydispersity, and there exists a critical point for polydispersity above which a crystal-like shell is unstable. In a particular case of bidisperse beds, the crystal-like shell only appears when the particle-particle friction is high enough. Finally, we compute the contact forces within particle-particle chains and in particle-wall contacts, which sustain the cylindrical shell, highlighting the dominant role of particle-particle forces.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Published in Open Access on this https URL
The European Physical Journal E, v. 49, 30, 2026
Universal Loop Statistics from Active Extrusion with Kinetic Barriers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
A. Chervinskaya, R. Metzler, K. E. Polovnikov
We develop a kinetic theory of cohesin-driven loop extrusion on a disordered chromatin track with transient barriers. In the stationary state, the mean loop size is shown to obey a universal law determined by the bare processivity and a renormalized obstacle density. Beyond the mean, one-sided extrusion always yields a single-exponential loop-length distribution, whereas two-sided extrusion produces a finite sum of exponential modes and, generically, a peaked distribution. Experimental CTCF-anchored loop statistics exhibit such a peak, thereby providing a direct discriminator of extrusion symmetry. The theory therefore establishes a unified framework for disorder-limited loop extrusion and supports a scenario in which both cohesin arms actively operate in living cells.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Biomolecules (q-bio.BM)
Hole concentrations in doped gray α-Sn on InSb and CdTe measured with infrared ellipsometry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Jaden R. Love, Carlos A. Armenta, Atlantis K. Moses, Haley B. Woolf, Jan Hrabovsky, Stefan Zollner, Aaron N. Engel, Christopher J. Palmstrøm
Gray tin ({\alpha}-Sn) layers with 30 nm thickness were grown on InSb (001) substrates using molecular beam epitaxy. The surface preparation of the substrates was adjusted to achieve either n-type or p-type doping in the {\alpha}-Sn layer. Fourier-transform infrared ellipsometry was used to find the temperature-dependent dielectric function of the {\alpha}-Sn layers from 0.03 to 0.8 eV and from 10 to 300 K. Because of the inverted band structure of {\alpha}-Sn, the spectra show a strong absorption peak at 0.45 eV due to transitions from the inverted {\Gamma_-^7} “electron” valence band to the {\Gamma_+^8} heavy hole valence band. Applying the Thomas-Reiche-Kuhn f-sum rule, the integrated oscillator strength of this peak was used to calculate the heavy hole concentration as a function of temperature. For a nearly intrinsic {\alpha}-Sn layer, the heavy hole concentration agrees well with predictions based on degenerate Fermi-Dirac statistics. Deviations from the intrinsic {\alpha}-Sn carrier concentrations are attributed to substrate surface preparation leading to the diffusion of donor or acceptor ions into the {\alpha}-Sn layer causing n-type or p-type doping.
Materials Science (cond-mat.mtrl-sci)
Control of turn-to-turn contact resistivity in resistively insulated REBCO coils
New Submission | Superconductivity (cond-mat.supr-con) | 2026-04-20 20:00 EDT
Jun Lu, Kwangmin Kim, Iain Dixon, Justin Deterding, Emsley Marks, Brent Jarvis, Denis Markiewicz, Hongyu Bai, Mark Bird
Resistively insulated (RI) REBCO magnets feature short ramp times and low ramp losses while maintaining the advantages of no-insulation coils with high engineering current density and tolerance for defects in the REBCO conductor. Control of the turn-to-turn contact resistivity Rc is key to RI technology. Rc must be sufficiently high to prevent a large transient current, which could result in high mechanical stress during magnet quenches. Meanwhile it must be lower than the quench propagation limit to avoid conductor burn-out during a quench. Therefore, it is critical to control Rc within a suitable range of values which is usually coil specific. Previously, we discovered that Rc between two REBCO tapes with a stainless steel interlayer decreases dramatically with contact pressure cycling by up to three orders of magnitude. This drastic change made it impossible to design a suitable Rc value for a stainless steel co-wound RI magnet. In this work, we first present methods for mitigating Rc pressure cycling sensitivity. We found that by adding conductive fillers, such as conductive paste or epoxy, the Rc load cycling sensitivity is largely mitigated. For dry-wound coils, Rc load cycling sensitivity is mitigated by coating REBCO tape with a layer of 2- 3 um of PbSn solder. In addition, Rc can be controlled by oxidizing the stainless steel co-wind tape by heating stainless steel tapes at different temperatures in air. Using above methods, short sample tests showed that Rc was controlled to prescribed values of 1000 and 5000 uOhm-cm2 and was not sensitive to contact pressure cycling up to 30,000 cycles at 4.2 K. The new Rc control method was applied to a 6 double-pancake test coil which was tested at 4.2 K. The Rc in this test coil was comparable with the short sample results. This demonstrated the ability of this new method to control Rc in large coils.
Superconductivity (cond-mat.supr-con)
21 pages, 15 figures
Exact Analysis of a One-Dimensional Yang-Gaudin Model with Two-Body Loss
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-04-20 20:00 EDT
We show that the one-dimensional Yang-Gaudin model with two-body loss remains exactly solvable irrespective of whether constituent particles are bosons or fermions. By relating the Liouvillian spectrum to the right eigenvalues of a non-Hermitian effective Hamiltonian obtained by complexifying the interaction strength, we derive a general expression for the initial particle-loss rate. We then solve the two-body problem exactly and show that, in the bosonic singlet sector, the effective Hamiltonian has real right eigenvalues and the master equation admits steady-state solutions. For many-body systems with three or more particles, we further show that dissipation reverses which spin configurations are most stable: in bosonic systems it favors antiferromagnetic-like configurations over ferromagnetic-like ones, whereas in fermionic systems it favors ferromagnetic-like configurations over antiferromagnetic-like ones.
Quantum Gases (cond-mat.quant-gas)
15 pages, 3 figures
Inelastic neutron scattering study on the AFM uniform spin-1/2 chain compound CuSb2O6
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Masashi Hasea, Minoru Soda, Takatsugu Masuda, Shinichi Itoh, Tetsuya Yokoo
We carried out inelastic neutron scattering experiments on a powdered sample of the antiferromagnetic (AFM) uniform spin-1/2 chain compound this http URL magnetic excitations appear in the energy range of 1.8 to 13 meV at 2.5 K below the AFM transition temperature (TN = 8.7 K).The gap value (1.8 meV) is close to that evaluated from the specific heat (1.51 meV). The excitations at 12.5 K (> TN) appear gapless. Thus, the 1.8 meV gap is caused by some anisotropy in spin-wave excitations. The gap excitations are strongest at 0.48 corresponding to a length of 0.66 nm. This result is consistent with the theoretical one that the interaction in a Cu pair with a length of 0.65562 nm (Jab) is strongest. The magnetic excitations can be explained by the AFM uniform XXZ chain with Jab = 6.437 meV and DJab = 0.063 meV. The 1.8 meV gap is caused by the small Ising anisotropy (DJab/Jab = 0.0098).
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 2 figures
Inductance Meets Memory in the Quantum Magnet Mn3Si2Te6
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Tristan R. Cao, Gabriel Schebel, Arabella Quane, Hengdi Zhao, Yu Zhang, Feng Ye, Longji Cui, Gang Cao
Orbital degrees of freedom offer a largely untapped route to emergent dynamical phenomena in correlated quantum materials. However, it remains unclear whether collective orbital states can intrinsically generate both reactive and memory functionalities in a bulk system. Here we show that in the ferrimagnet Mn3Si2Te6, nonequilibrium reconfiguration of chiral orbital currents produces both emergent inductance and nonvolatile memristance as intrinsic properties of a single crystal. At low frequency and under a magnetic field along the c axis, coherent orbital-current domains generate robust clockwise inductive I-V loops. At higher frequency and low field, current-driven first-order reconfiguration leads to incomplete reversal and metastable trapping, producing an intrinsic electromotive force and a finite remanent voltage at zero current. These results establish orbital currents as a class of quantum state variables that encode both reactive and memory functionalities, opening routes toward intrinsically reconfigurable and energy-efficient electronic systems.
Strongly Correlated Electrons (cond-mat.str-el), Applied Physics (physics.app-ph)
5 figures. Communications Physics (2026)
Facet-dependent Chemical Kinetics Governed Growth of Twisted Graphene Layers with Pre-designed Angles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Chaowu Xue, Mengzhao Sun, Zixuan Zhou, Zhuoran Yao, Li-Qun Shen, Xiao Kong, Honglong Zhao, Feng Ding, Marc Willinger, Zhongkai Liu, Zhu-Jun Wang
Twisted graphene layers (TGLs) provide a powerful platform for investigating multiple quantum phenomena, yet their scalable deployment is hindered by the lack of reliable synthesis with precise angle. Here, benefited from a deeper understanding of the interplay between grain index and graphene growth kinetics, we report a scalable strategy to grow TGLs with pre-designed twist angles on platinum (Pt) via chemical vapor deposition (CVD), Through a combination of complementary in situ methods, we identified the activity sequence of different Pt grains and attributed it to the area ratio of exposed (110) facets during graphene-induced surface reconstruction. Moreover, we revealed that CVD-grown graphene orientation is determined by the grain-orientation-dependent surface morphology. By leveraging the so-established correlations between grain index with both graphene growth priority and its orientation, we achieve controlled folding and tearing of graphene overlayer using a pair of adjacent grains with dramatically different catalytical activity and kink-free atomic steps. We reveal that overlayer-induced step bunching and terrace reconfiguration critically govern the domain morphology and folding direction. Building on this mechanistic insight, we demonstrate a substrate-engineering framework where specific platinum grains are rationally selected to yield TGLs with pre-designed twist angles, including magic angle with flat band dispersion. This work not only highlights fundamental kinetics of Pt catalyzed graphene CVD growth, but also offers a generalizable methodology for manipulating foldable two-dimensional materials via dynamic substrate reconstruction, exampled by programmable growth of high-quality TGLs on open surfaces.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
43 pages, 6 figures. Main text only, including Methods and References
Fully compensated and uncompensated ferrimagnetic ferrovalley semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Weifeng Xie, Libo Wang, Yunliang Yue, Xiong Xu, Huayan Xia, Hui Wang
Altermagnets (AMs) and fully compensated ferrimagnets (FC-FIMs) are emerging classes of magnetic materials that combine the advantages of antiferromagnets and ferromagnets. Here, we elucidate the mechanism behind the uniaxial strain-driven transformation from AM to FC-FIM and find that the accompanying non-relativistic valley polarization is positively correlated with the net magnetic moment between magnetic atoms in opposite spin sublattices. We then propose an uncompensated ferrimagnetic monolayer VCrSeTeO to achieve large intrinsic valley polarization. Spin-orbit coupling (SOC) is shown to further increase the valley polarization to over 400 meV under uniaxial strains and the reason is explained in terms of SOC perturbation theorem. Furthermore, we reveal a distinctive anomalous valley Hall effect in which the valley Hall voltage is reversed within the same valley in ferrimagnet VCrSeTeO. This work proposes a strategy for realizing giant valley polarization and provides theoretical guidance for the application of ferrimagnetic ferrovalley semiconductors derived from altermagnets in valleytronics.
Materials Science (cond-mat.mtrl-sci)
Growth of quantum dots by droplet etching epitaxy in molecular beam epitaxy: theory, practice, and review
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Declan Gossink, Undurti S. Sainadh, Glenn S. Solomon
GaAs quantum dots grown by droplet etching epitaxy are high-quality solid-state sources of quantum light. Despite implementation in devices that exploit quantum phenomenon, a comprehensive review on the crystal growth of quantum dots grown by droplet etching epitaxy is absent, unlike for other quantum dot growth techniques such as the related droplet epitaxy method or Stranski-Krastanov growth of InAs quantum dots. This review presents a detailed overview of the droplet etching epitaxy growth technique in the molecular beam epitaxy environment, with emphasis on the growth parameters necessary to realize high-quality quantum dots. We systematically cover the three main phases of droplet etching epitaxy - droplet deposition, droplet etching, and nanohole regrowth - and relate experimental results to theories on crystal growth. The review concludes with an introduction to GaAs quantum dot photoluminescence and the extension of droplet etching epitaxy beyond the AlGaAs/GaAs material system.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
19 pages, 6 figures
Flat-band energy filtering in interacting systems: conditions for improving thermoelectric performances
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
F. Cosco, R. Tuovinen, F. Plastina, N. Lo Gullo
Motivated by recent theoretical and experimental studies on the role of flatbands in the thermoelectric properties of Ni$ _3$ In$ _{1-x}$ Sn$ _x$ compounds, we investigate electron transport in two minimal one-dimensional flatband models, the sawtooth and diamond chains, which differ in a crucial aspect: the flatband is separated from the dispersive band by a finite gap in the former, while the two bands touch in the latter. Using a non-equilibrium Green function framework with interactions treated at the Hartree-Fock and GW levels, we compute the full set of thermoelectric coefficients and the figure of merit $ zT$ as functions of gate voltage and temperature. We show that, contrary to naive expectation, a perfectly isolated flat-band is a physically ill-founded thermoelectric: the electrical conductivity vanishes as the chemical potential enters the flat-band, rendering the large Seebeck coefficient and the apparent violation of the Wiedemann-Franz law physically meaningless. Optimal thermoelectric performance is instead achieved just below the flat-band edge, where the transmission function varies most rapidly with energy, consistent with the Mahan-Sofo picture, and requires a finite broadening of the flat-band through hybridization with dispersive states. We further show that electron-electron interactions renormalize the flat-band structure itself, inducing an interaction-driven narrowing of the bandwidth and, in the diamond chain, a correlation-induced opening of a gap between the flat-band and the dispersive band near half-filling. Mean-field treatments are found to systematically overestimate (zT), highlighting the importance of beyond-mean-field correlations for quantitatively reliable predictions in flat-band thermoelectrics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 8 figures
Current-Induced Dynamics and Instability Pathways of Skyrmioniums in Chiral Magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Kaito Nakamura, Yuka Kotorii, Andrey O. Leonov
We present a comprehensive study of current-driven dynamics, transformations, and instabilities of skyrmioniums in chiral magnetic films, considering both isolated objects and collective states forming skyrmionium-based meta-matter. Using micromagnetic simulations combined with an analytical description based on the generalized Thiele equation, we clarify how the internal structure of skyrmioniums governs their nonequilibrium response to electric currents. Despite having zero total topological charge, skyrmioniums exhibit a finite transverse velocity under applied currents. We show that this skyrmionium Hall effect originates from an imbalance between positive and negative topological contributions of the inner skyrmion and surrounding ring, which typically occupy different areas. Current-induced deformations further enhance this imbalance, yielding Hall angles comparable to those of skyrmions. At higher current densities, skyrmioniums undergo distinct instabilities depending on magnetic field and uniaxial anisotropy, including elongation, collapse into a skyrmion, transformation into a topologically trivial droplet, and expansion into stripe textures. We map these regimes in current–field and current–anisotropy phase diagrams and resolve their microscopic pathways via the evolution of topological charge and local rotational measures. Beyond isolated textures, mixed skyrmion–skyrmionium lattices display rich collective dynamics, including elastic transport, polymorphic transitions, soliton exchange, and stripe formation. Pulsed currents provide additional control, enabling access to regimes beyond continuous driving. Our results establish skyrmioniums and their meta-matter as tunable nonequilibrium systems probing the topological energy landscape far from equilibrium.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph)
20 pages, 10 figures
Amplitudes of Hall field-induced resistance oscillations with a two-harmonic density of states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
We derive explicit strong-field asymptotics for the normalized differential resistance in Hall field-induced resistance oscillations (HIRO) within the Vavilov-Aleiner-Glazman kinetic framework. For a single-harmonic density of states, the leading oscillation amplitude is set by the full backscattering rate $ 1/\tau(\pi)$ . Extending the theory to a two-harmonic density of states, we show that the off-diagonal mixed kernel $ \gamma_{12}$ admits an exact single-integral representation, from which the strong-field asymptotics follow directly. The resulting odd harmonics, notably $ m=1$ and $ m=3$ , have coefficients determined by combinations of $ 1/\tau(0)$ and $ 1/\tau(\pi)$ , while the leading $ m=2$ amplitude remains unchanged. On exact-kernel mock data generated and fit within the same model, with $ \tau_{\rm tr}$ and $ \tau_{\rm in}$ held fixed, the resulting extraction protocol recovers $ \tau_q$ , $ \tau(\pi)$ , and – when the $ m=1,3$ harmonics are resolved – $ \tau(0)$ to sub-percent accuracy, with $ \tau(0)$ providing a consistency check on the disorder description.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, REVTex two-columns, 4 figures
Extracting conformal data from finite-size tensor-network flow in critical two-dimensional classical models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
We present a general framework for extracting conformal data from critical two-dimensional classical lattice models using finite-size tensor-network flow. The central idea is to identify, from transfer-matrix spectra, a self-consistent finite-size window together with a crossover scale that separates the finite-size-scaling regime from the finite-entanglement-scaling regime induced by bond-dimension truncation. Within this window, the central charge, scaling dimensions, and conformal spins can be estimated without requiring a unique critical fixed-point tensor or detailed prior knowledge of the underlying conformal field theory. We benchmark the framework using three tensor-network renormalization schemes for the critical two-dimensional Ising and three-state clock models. Across schemes, we find robust universal behavior below the crossover scale, enabling accurate extraction of conformal data up to relatively high conformal levels. The analysis also yields a natural operational definition of entanglement scaling for classical tensor-network calculations and, in turn, a complementary estimator of the central charge.
Statistical Mechanics (cond-mat.stat-mech)
Phase Transitions as the Breakdown of Statistical Indistinguishability
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
Taiyo Narita, Hideyuki Miyahara
We introduce a novel characterization of phase transitions based on hypothesis testing.
In our formulation, a phase transition is defined as the breakdown of statistical indistinguishability under vanishing parameter perturbations in the thermodynamic limit.
This perspective provides a general, order-parameter-free framework that does not rely on model-specific insights or learning procedures.
We show that conventional approaches, such as those based on the Binder parameter, can be reinterpreted as special cases within this framework.
As a concrete realization, we employ a distribution-free two-sample run test and demonstrate that the critical point of the two-dimensional Ising model is accurately identified without prior knowledge of the order parameter.
Statistical Mechanics (cond-mat.stat-mech), Artificial Intelligence (cs.AI), Methodology (stat.ME)
Persistence of large and gate-tunable anisotropic magnetoresistance in an atomically thin antiferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Cheol-Yeon Cheon, Kenji Watanabe, Takashi Taniguchi, Alberto F. Morpurgo, Dmitry Lebedev
Anisotropic magnetoresistance (AMR) offers a robust electrical readout of antiferromagnetic (AFM) states, playing a central role in the rapidly advancing field of AFM spintronics. Despite its great versatility, electrical probing of the Néel vector via AMR remains challenging in the ultrathin limit due to interface disorder and reduced dimensionality. Here, we demonstrate electrical readout of the Néel vector down to 1.3 nm (two layers) in the two-dimensional van der Waals (vdW) AFM semiconductor NiPS3. Leveraging spin-flop-mediated rotation of the Néel vector and using both transistor and tunnel-junction device geometries, we identify two distinct AMR contributions in NiPS3, that dominate at low and high charge densities, respectively. We achieve full gate control over these contributions, enabling tunability of both the magnitude and sign of magnetoresistance. Our results establish semiconducting vdW antiferromagnets as a rich platform for studying AMR in the ultrathin limit, opening new avenues for multifunctional AFM spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Direct Orientation Contrast Imaging of Anti-Phase Domains on III-V Materials Using Scanning Electron Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Brieg Le Corre, Clothilde Grenèche, Rozenn Bernard, Tony Rohel, Antoine Létoublon, Wijden Khelifi, Julie Le Pouliquen, Arnaud Grisard, Sylvain Combrié, Bruno Gérard, Abdelmounaim Harouri, Luc Le Gratiet, Grégoire Beaudoin, Konstantinos Pantzas, Isabelle Sagnes, Oliver Skibitzki, Gilles Patriarche, Charles Cornet, Yoan Léger
Direct orientation contrast imaging of zinc-blende III-V materials is studied using scanning electron microscopy. A quantitative approach is taken using a 3 {\mu}m thick orientation-patterned GaP grown on GaAs sample, studying the anti-phase domain contrast with respect to the electron beam energy and the tilt angle. A qualitative approach is taken for III-V grown on non-polar materials with and without chemical mechanical polishing. Finally, a processing of the acquired image for GaP on Si reveals in plane preferential anti-phase boundaries.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Coupled-channels method for the scattering hypervolume in ultracold atomic three-body collisions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-04-20 20:00 EDT
P.J.P. Kersbergen, J. van de Kraats, D.J.M. Ahmed-Braun, S.J.J.M.F. Kokkelmans
We introduce a novel coupled-channels method for elastic three-body scattering in systems of identical bosonic alkali-metal atoms. The approach relies on the numerically exact two-body off-the-energy-shell transition matrix, constructed from realistic multichannel molecular interaction potentials that support many bound states. By rigorously accounting for this off-shell structure, the method captures both the short-range physics as well as multichannel couplings characteristic of alkali-metal potentials without resorting to model pseudopotentials. The central output is the complex three-body scattering hypervolume – the three-body analogue of the two-body scattering length – which we obtain with controlled and verifiable numerical accuracy. As a realistic benchmark, we apply our framework to spin-polarized potassium-39, performing full coupled-channels three-body scattering calculations and extracting the hypervolume over experimentally relevant conditions. The method is general and transferable to other atomic species and interaction models featuring deep molecular potentials with an arbitrarily large number of bound states.
Quantum Gases (cond-mat.quant-gas)
14 pages, 8 figures
General perturbative framework for kinetics of rare transitions in 1-dimensional active particle systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
Vito Seinen, Peter G. Bolhuis, Daan Crommelin, Sara Jabbari Farouji, Michel Mandjes
We present a theoretical framework that enables investigating rare transitions in a general model of an active particle in an external potential, with the thermal Active Ornstein-Uhlenbeck Particle (AOUP) appearing as a special case. Using a projection-operator formalism, we compute transition rates perturbatively in two distinct asymptotic regimes. In the regime of small persistence times-where the activity evolves much faster than the particle’s position-integrating out the activity reproduces the rates previously reported in the literature. In the opposite regime of large persistence times, we instead integrate out the position and obtain the corresponding rates analytically. Together, these asymptotic expansions uniquely specify a rational approximation that remains accurate across intermediate persistence times. As a result, we obtain an analytic expression for the rate valid across all persistence times and activity strengths in the rare-event limit, which are in excellent agreement with numerical simulations. The presented framework applies to rare transitions in a broad class of driven systems.
Statistical Mechanics (cond-mat.stat-mech)
16 pages, 3 figures
Voids in liquids: peculiarities of molecular dynamics simulation of fluid systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Molecular dynamics is a powerful tool to investigate the properties of fluid systems. However, a correct interpretation of the results of simulations is required. In particular, some simulations show appearance of large voids in liquids, which contradicts our common sense on what is liquid. In the present paper we discuss the origin of large cavities liquids in molecular dynamics simulations. We demonstrate that the cavities appear either if the temperature of the system is above the critical temperature of liquid-gas transition or if the system is in two-phase liquid-gas region. These conclusions are illustrated by several examples from literature and our own simulations.
Soft Condensed Matter (cond-mat.soft)
Phase behavior of thermoresponsive colloids drives re-entrant plasmon coupling
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Angela Capocefalo (1,2), Francesco Brasili (1,2), Javier Pérez (3), Edouard Chauveau (4), Stefano Casciardi (5), Andrea Militello (5), Francesco Sciortino (2), Emanuela Zaccarelli (1,2), Federico Bordi (2), Domenico Truzzolillo (4), Simona Sennato (1,2) ((1) Institute for Complex Systems of National Research Council, (2) Department of Physics of Sapienza University of Rome, (3) Synchrotron SOLEIL, (4) Laboratoire Charles Coulomb of CNRS-Université de Montpellier, (5) National Institute for Insurance against Accidents at Work)
Plasmonic nanoparticles (NPs) integrated within thermoresponsive polymeric microgels provide a versatile platform for the realization of stimuli-responsive optical materials, where the microgel volume phase transition enables dynamic control of plasmon coupling. This study uncovers a counter-intuitive re-entrant behavior with increasing NP loading in which plasmon coupling initially strengthens and subsequently weakens beyond a critical NP-to-microgel number ratio. By combining light and X-ray scattering techniques with optical spectroscopy and electrophoretic mobility measurements, it is demonstrated that plasmon coupling is governed not only by the interparticle distance between NPs confined within individual microgels, but also by the colloidal stability of the hybrid complexes. At intermediate NP loadings, surface charge inhomogeneities induced by NP adsorption promote aggregation of microgel-NPs complexes, resulting in enhanced plasmon coupling. In contrast, when the complexes remain colloidally stable, coupling is dictated solely by NP organization within the corona of individual microgels. A quantitative relationship between plasmon coupling and interparticle distance reveals two distinct coupling regimes. This behavior is rationalized through a phase diagram linking colloidal stability to optical response. These findings identify colloidal stability as a key parameter for designing soft plasmonic systems with programmable optical properties.
Soft Condensed Matter (cond-mat.soft)
Enhancing Neural-Network Variational Monte Carlo through Basis Transformation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Zhixuan Liu, Dongheng Qian, Jing Wang
Neural-network variational Monte Carlo (NNVMC) has emerged as a powerful tool for solving quantum many-body problems, yet systematic pathways for improving its accuracy remain largely heuristic. Here, we introduce a physically motivated basis transformation for NNVMC that enhances variational expressivity without increasing the complexity of the neural-network ansatz itself. By formulating the many-body wave function in a Gaussian basis, we introduce a single learnable locality parameter, $ \alpha$ , that reshapes the target ground state into a more learnable representation. This approach introduces minimal computational overhead and can be readily combined with existing neural-network architectures. Using the three-dimensional homogeneous electron gas as a benchmark, we show that the optimized basis transformation consistently lowers the variational energy for both FermiNet and message-passing neural-network architectures. Notably, for the latter, it enables a more precise determination of the Fermi liquid to Wigner crystal phase transition. More broadly, our results highlight basis transformation as a new route to improving NNVMC in continuous space, showing that accuracy can be enhanced not only by refining the ansatz but also by making the target ground state easier to represent.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
7 pages, 4 figures
Experimentally-validated multi-slice simulation of electron diffraction patterns
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Xinke Xiao, Tianle Ma, Lingxuan Shao (SJTU), Jun Liu, Qiwei Shi (SJTU), Canying Cai, Stéphane Roux (LMPS)
High-Resolution Electron Backscatter Diffraction (HR-EBSD) has advanced rapidly in recent years, significantly improving elastic strain measurements and dislocation density evaluation with submicron spatial resolution. To achieve better accuracy in the measurements, high-quality dynamical simulation patterns are required to be matched with experimental ones. Currently, the most widely used pattern simulation method, the Bloch Wave method (BW), can accurately predict the positions and brightness of Kikuchi poles and bands, but is intrinsically limited to perfect crystal structures. Another simulation scheme, the multi-slice method (MS), follows the evolution of electron waves as they travel through the sample. MS is advantageous in simulating various defect structures with more diffraction details. Yet, it is mainly considered for theoretical developments and has not been compared to experimental data. This paper optimizes the MS method by abandoning the high-energy hypothesis and utilizing higher-order Taylor expansions to approach the forward-only Schrodinger equation. Experimental EBSD patterns of polycrystal Al-Mg alloys are used to challenge MS simulations as a reference for indexation. It is demonstrated that the 5th-order expansion of MS, referred to as MS5, achieves a good balance between computational cost and pattern precision. A tailored isotropic distortion correction model and standard stereographic triangle reconstruction enhance the precision of MS5 to be comparable with BW. To the best of our knowledge, this study provides the first comparison of MS EBSD simulations with experimental data. It opens new possibilities for EBSD characterization, such as reproducing diffraction patterns of crystals with various defects.
Materials Science (cond-mat.mtrl-sci)
Micron, 2026, 204, pp.104025
Experimental quantification of electronic symmetry breaking through orbital hybridization phase
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Shungo Aoyagi, Shunsuke Kitou, Yuiga Nakamura, Taka-hisa Arima, Naoya Kanazawa
Symmetry classification of crystal structures has been central to predicting physical properties of materials. While such structural classification identifies which physical responses are symmetry-allowed, the magnitudes of these responses are governed by the degree of symmetry breaking in the electronic state. However, a well-defined quantitative descriptor for the electronic symmetry breaking has been established only in limited cases such as electric polarization and magnetization. No analogous descriptor exists for most other types, including chirality. Here, we propose an experimental framework for quantifying electronic symmetry breaking from the anisotropy of valence electron density distribution. We show that the orbital hybridization phases governing this anisotropy can be uniquely determined under site symmetry constraints. Applying this framework to structurally chiral transition-metal silicides, we determine hybridization phases from their valence electron densities observed by synchrotron X-ray diffraction. From the obtained complex hybridization, we quantify an electronic chirality $ \chi$ and theoretically demonstrate that it is directly proportional to circular dichroism, establishing $ \chi$ as a predictive descriptor of chiral responses. This approach is systematically applicable to various point groups, offering a general route to quantifying electronic symmetry breaking and predicting associated physical properties.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
21 pages, 7 figures
On the role of the slowest observable in one-dimensional Markov processes to construct quasi-exactly-solvable generators with $N=2$ explicit levels
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
The construction of Quasi-Exactly-Solvable quantum Hamiltonians where only the two first eigenstates $ \Phi_0(x)$ and $ \Phi_1(x)$ of energies $ E_0$ and $ E_1$ are explicit is revisited from the point of view of one-dimensional Markov processes satisfying detailed-balance, whose generators are related to quantum Hamiltonians via similarity transformations. Here the lowest energy vanishes $ E_0=0$ and is associated the conservation of probability and to the steady state $ P_\ast(x)$ , while $ E_1>0$ is the rate that governs the exponential relaxation towards the steady-state, and is associated to the slowest observable $ L_1(x)$ that corresponds to the ratio $ \frac{\Phi_1(x) }{\Phi_0(x)}$ of the two quantum eigenstates. Our main conclusion is that the Markov perspective leads to interesting re-interpretations and that the construction of quasi-exactly-solvable models with $ N=2$ explicit levels is more intuitive and technically simpler if one takes the slowest observable $ L_1(x)$ as the central object from which all the other properties can be reconstructed. This general approach is then applied to Fokker-Planck generators in continuous space and to Markov jump generators on the lattice.
Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)
33 pages
Ultrafast Current Switching from Quantum Geometry in Semimetals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Youngjae Kim, Sejoong Kim, Jun-Won Rhim
Technological progress towards next-generation electronics critically relies on achieving faster switching with reduced energy consumption. Because device operation speeds are fundamentally constrained by the intrinsic properties of constituent materials, identifying systems with inherently superior switching capabilities is essential. Here, we propose that semimetallic systems characterized by non-trivial quantum geometry, including quadratic band-touching semimetals and singular flat bands, can serve as a promising platform for ultrafast switching at voltages compatible with modern electronics. We show that, in such quantum geometric semimetals, an electric current is generated instantaneously upon application of a moderate external electric field, reaching its steady-state value. As a consequence, the current exhibits rapid and stable on-off switching behaviour under periodic optical pulse trains, demonstrating robustness under experimentally feasible conditions. In terms of switching speed, this quantum geometric semimetal outperforms conventional metals, semiconductors, and graphene. We identify the microscopic origin of this behaviour as interband coupling governed by the Hilbert-Schmidt quantum distance, together with a finite density of states at the band-touching point. This mechanism further leads to a universal classification of conductivity for both gapless and gapped quantum geometric semimetals. Finally, first-principles calculations suggest realistic material platforms, including bilayer graphene, cyclic graphene, monolayer bismuth and V3F8-in which the predicted instantaneous current switching can be directly realized, further supported by time-dependent density functional theory simulations performed for representative systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
23 pages, 5 figures
Antiferromagnetic Dimers in the Parent Phase of a Correlated Kagome Superconductor
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Yifan Wang, Chenchao Xu, Yi Liu, Jinke Bao, Jiayu Guo, Xiaoran Yang, Yuiga Nakamura, Hiroshi Fukui, Taishun Manjo, Daisuke Ishikawa, Alfred Q. R. Baron, Saizheng Cao, Rui Li, Zilong Li, Yanan Zhang, Ruihan Chen, Ming Shi, Huiqiu Yuan, Guanghan Cao, Chao Cao, Yu Song
Kagome metals are prone to charge-density wave (CDW), magnetic, and superconducting phases, with their flat electronic band conducive for correlated physics. In contrast to the weakly correlated $ A$ V$ _3$ Sb$ _5$ ($ A$ = K, Rb, Cs) kagome metals with a $ 2\times2$ CDW, CsCr$ _3$ Sb$ _5$ is a correlated metal with a flat band close to the Fermi level, and exhibits a $ 4\times1$ CDW intertwined with magnetic order. Under pressure, the intertwined orders are suppressed and give way to a dome of superconductivity that emerges from a non-Fermi liquid normal state. Here, we solve the crystal structure of the $ 4\times 1$ CDW state in CsCr$ _3$ Sb$ _5$ , and show it consists of Cr dimers separated by Cr chains. First-principles calculations show the dominant exchange interaction is antiferromagnetic within the dimers, while the intra-chain and dimer-chain couplings are much weaker. The CDW transition of CsCr$ _3$ Sb$ _5$ is found to be more strongly first-order than those in $ A$ V$ _3$ Sb$ _5$ , without significant soft phonons or diffuse scattering above the CDW transition temperature. These findings suggest that fluctuating antiferromagnetic dimers may play a major role in the electron pairing of superconducting CsCr$ _3$ Sb$ _5$ .
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Extension of the iterated perturbation theory at arbitrary fillings to nonequilibrium steady states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Tommaso Maria Mazzocchi, Enrico Arrigoni
We extend the Kajueter-Kotliar [Phys. Rev. Lett. 77, 131 (1996)] iterated perturbation theory (KK-IPT) away from half filling to nonequilibrium steady states. We benchmark the resulting nonequilibrium KK-IPT approach against the auxiliary master equation approach (AMEA), whose accuracy is controlled in and out of equilibrium. As expected, in equilibrium, KK-IPT reproduces the AMEA results for different fillings with high accuracy at the level of both spectral properties and electron densities. Out of equilibrium, we study quantum transport across a correlated impurity and compute the differential conductance and spectral functions. We find very good agreement between nonequilibrium KK-IPT and AMEA in the parameter regime where the latter is reliable, in particular at moderate temperatures and biases. These results support nonequilibrium KK-IPT as an approximate description of nonequilibrium steady states away from half filling. Although a controlled benchmark is not available in the low-temperature, low-bias regime, where AMEA becomes less reliable, nonequilibrium KK-IPT remains numerically stable in those regions, suggesting that it may provide a useful alternative for nonequilibrium calculations in this regime.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 5 figures, comments are welcome
Ergodic properties of functionals of Gaussian processes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
Vicenç Méndez, Carlos Hervás, Rosa Flaquer-Galmés
We derive the first two moments of generic positive stochastic functionals in terms of the one- and two-time probability density functions of the underlying random walk, and we prove ergodicity of observables in stationary random walks. These general results are applied to the half-occupation time and the occupation time in an interval of a Gaussian random walk, for which we obtain exact analytic expressions for the first two moments. We then extend the analysis to scaled Brownian motion and fractional Brownian motion, computing the ergodicity breaking parameter and establishing a simple scaling form for the probability densities of occupation times. Within the framework of infinite ergodic theory, we further identify universal properties of positive observables. All analytical predictions are fully confirmed by numerical simulations.
Statistical Mechanics (cond-mat.stat-mech)
Physical Review E 112 (6 Dec. 2025), p. 064111
Identification and Structural Characterization of Twisted Atomically Thin Bilayer Materials by Deep Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Haitao Yang, Ruiqi Hu, Heng Wu, Xiaolong He, Yan Zhou, Yizhe Xue, Kexin He, Wenshuai Hu, Haosen Chen, Mingming Gong, Xin Zhang, Ping-Heng Tan, Eduardo R Hernández, Yong Xie
Two-dimensional materials are expected to play an important role in next-generation electronics and optoelectronic devices. Recently, twisted bilayer graphene and transition metal dichalcogenides have attracted significant attention due to their unique physical properties and potential applications. In this study we describe the use of optical microscopy to collect the color space of chemical vapor deposition (CVD) molybdenum disulfide ($ \mbox{MoS}_2$ ), and the application of a semantic segmentation convolutional neural network (CNN) to accurately and rapidly identify thicknesses of $ \mbox{MoS}_2$ flakes. A second CNN model is trained to provide precise predictions on the twist angle of CVD-grown bilayer flakes. This model harnessed a dataset comprising over 10,000 synthetic images, encompassing geometries spanning from hexagonal to triangular shapes. Subsequent validation of the deep learning predictions on twist angles was executed through the second harmonic generation and Raman spectroscopy. Our results introduce a scalable methodology for automated inspection of twisted atomically thin CVD-grown bilayer.
Materials Science (cond-mat.mtrl-sci)
Nano Lett. 2024, 24, 2789-2797
Flash temperature in sliding contacts: comparing theory with experiments
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
The temperature increase in the contact regions between solids in sliding contact has a huge influence on friction and wear. Here we test an analytical theory for the flash temperature, valid for randomly rough surface with multiscale roughness, by comparing the theory predictions with the experimental results of Sutter et al \cite{Sutter} for steel sliding on steel. The theory, which is based on the study of stress and temperature correlation functions, is valid for randomly rough surfaces with roughness on arbitrary many decades in length scale. Within the uncertainty of the experimental data (mainly the surface roughness power spectrum and the steel penetration hardness), there is good agreements between the theory and the experimental results.
Soft Condensed Matter (cond-mat.soft)
Charge Density Wave Driven Topological Phase Transition in Vortices
New Submission | Superconductivity (cond-mat.supr-con) | 2026-04-20 20:00 EDT
Zhenhua Zhu, Ziqiang Wang, Dong E. Liu
The interplay between charge density waves (CDWs) and superconductivity is a central theme in quantum materials, yet how CDW phase textures govern vortex topology remains poorly understood. We develop a theoretical framework showing that the phase of a stripe CDW can switch a magnetic vortex between topological and trivial regimes. Motivated by recent experiments, we propose two candidate mechanisms enabling phase-controlled switching of vortex topology. In a direct-modulation scenario, the CDW acts as a periodic potential that locally renormalizes band parameters and can induce topological transitions, but it generally cannot reproduce the symmetric node/antinode trend without fine tuning. In contrast, in an inversion-symmetry-breaking (ISB) scenario, a CDW node pinned to the vortex center breaks local inversion and allows for the mixture of spin-triplet pairing of Cooper pairs, producing a robust topological transition when this component dominates. Our results suggests CDW phase as a possible local handle to tune and test vortex topology.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Laser induced surface nitriding of niobium: phase evolution and superconducting behaviour
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
J. Frechilla, A. Frechilla, G.F. de la Fuente, A. Larrea, L.A. Angurel, E. Martínez
Laser nitriding represents a versatile approach for tailoring the surface properties of metals. Up to now, its effect on the superconducting response of niobium nitrides remains largely unexplored. In this work, the nitriding process of niobium by laser irradiation under a controlled nitrogen atmosphere up to 2.50 bar, using a nanosecond pulsed laser with wavelength of 1064 nm has been investigated. By independently tuning the nitrogen pressure, the two-dimensional accumulated fluence ($ F_{2D}$ ) and the laser irradiance, a laser-processing map for the formation of either a combination of $ \beta$ -Nb$ _2$ N (hexagonal) and $ \gamma$ -Nb$ 4$ N$ {3\pm x}$ (tetragonal) phases or only the $ \beta$ -phase has been established. Systematic analysis by X-ray diffraction, scanning electron microscopy and electron backscatter diffraction revealed that the nitrogen-rich $ \gamma$ -phase forms in the near-surface layer through melting when $ F{2D}$ exceeds a certain value ($ > 50 ,\mathrm{kJ/cm^2}$ at 2.50 bar). A $ \beta$ -layer is observed underneath, and further inside, there is a band of embedded $ \beta$ -grains in the Nb matrix. Their size gradually decreases with increasing distance to surface, suggesting thermal gradients and a diffusion formation mechanism. When the $ \gamma$ -phase becomes predominant, a significant increase in the superconducting critical temperature is observed, up to $ T_c \approx 15,\mathrm{K}$ , and magnetic irreversibility. For low $ F{2D}$ values ($ \approx 7.5 ,\mathrm{kJ/cm^2}$ at 1.50-2.50 bar), the formation of a uniform nitride layer composed of sub-micron-sized $ \beta$ -Nb$ _2$ N grains results in a ca. fourfold enhancement in surface microhardness. These findings provide fundamental insights into laser-induced nitriding of niobium to engineer mechanically robust and superconducting Nb-N layers.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Observation of ring states in a delicate topological insulator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Caroline Tornow, Julia Rupprecht, Pascal Engeler, Ute Drechsler, Kukka-Emilia Huhtinen, Chiara Devescovi, Sebastian D. Huber
Topological insulators are typically characterized by particularly stable properties, such as global invariants, and can be identified by probing their robust surface states. A recently discovered novel form of band topology, delicate topology, challenges this paradigm: its defining property, multicellularity, can be removed by introducing a coupling to local orbitals anywhere in the spectrum, even far above the relevant band gap. This makes it hard to diagnose delicate topology with conventional probes that access only low-energy degrees of freedom. Here, we introduce strong local impurities as a spectroscopic probe of a delicate topological insulator which we realize in a phononic metamaterial. By tuning the impurity strength and performing orbital-resolved readout, we observe recently proposed indicators of topology: ring states, in-gap bound states whose frequencies remain pinned in the strong-impurity limit while their real-space profiles form a pronounced ring around the impurity site. We find that these ring states persist even when the multicellularity in our system is removed by a weakly hybridizing additional orbital. Our results establish impurity-induced ring states as probes of complex multiband physics, including delicate topological phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Machine Learning and Deep Learning in Quantum Materials: Symmetry, Topology, and the Rise of Altermagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Mahyar Hassani-Vasmejani, Hosein Alavi-Rad, Meysam Bagheri Tagani
The landscape of condensed matter physics is facing an unprecedented data surge driven by high-throughput ab initio workflows and rapidly expanding experimental datasets. Traditional first-principles methods such as Density Functional Theory (DFT), despite their foundational role, suffer from cubic scaling, creating a major bottleneck when exploring the vast chemical space of quantum materials. This review analyzes how Machine Learning (ML) and Deep Learning (DL) are overcoming these limitations and accelerating the discovery of exotic phases of matter. We examine the shift from rigid descriptor-based models to flexible, symmetry-aware architectures, particularly E(3)-equivariant Graph Neural Networks (GNNs) that respect rotational and translational invariance. A central focus is the automated identification of topological phases, where ML models exploit symmetry indicators and elementary band representations to diagnose non-trivial topology without costly band structure integrations.
The discussion culminates in a case study of the Altermagnet, a recently identified third class of magnetism beyond the ferromagnetic, antiferromagnetic dichotomy. We highlight how specialized AI search engines, combining graph theory with crystallographic symmetry analysis, have uncovered d-wave, g-wave, and even i-wave altermagnets, expanding the known landscape of magnetic order. The review concludes by addressing the interpretability gap and advocates for symbolic regression and active-learning frameworks to connect black-box predictions with experimentally verifiable mechanisms.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
30 pages, 8 figures
Disambiguating electrical detection of magnetization dynamics in magnetic insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
Hanchen Wang, William Legrand, Shangyuan Wang, Davit Petrosyan, Hiroki Matsumoto, Richard Schlitz, Ka Shen, Pietro Gambardella
Electrical detection of magnetization dynamics in magnetic insulators underpins both fundamental studies of magnon transport and the development of low-loss magnonic devices. In heavy-metal/magnetic-insulator heterostructures, spin pumping and spin-torque ferromagnetic resonance (ST-FMR) are widely used for this purpose and are often treated separately in different measurement geometries. In practice, the competition between these two effects gives rise to electrical voltage signals of opposite signs, which can lead to ambiguous interpretations of the underlying physics. Here, we show how to disambiguate their respective contributions and provide a framework for interpreting experiments involving microwave excitation of magnetic insulators and detection of magnetization dynamics via spin-charge conversion in heavy metals. We systematically investigate spin pumping and ST-FMR in nonlocal and local devices using Pt-capped thin films of thulium and bismuth-yttrium iron garnets. We show how spin-wave character, magnetic dissipation, magnetic field orientation and device geometry govern the sign and magnitude of the resulting signals. In several cases, the voltage generated by microwave excitation changes sign between an out-of-plane or in-plane magnetic configuration. We disentangle a contribution due to spin pumping, induced by exponentially decaying propagating spin waves, and a weakly distance-dependent contribution from ST-FMR, remotely induced by inductive coupling. We show that both the spin wave excitation profile across the film thickness and magnetic damping largely determine which of the two contributions dominates. Hence, the sign of the electrical signal cannot be uniquely assigned to the chirality of the magnon modes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Mircomechanical insights into unconstrained grain boundary sliding
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Divya Sri Bandla, Subin Lee, Christoph Kirchlechner
Grain boundary sliding (GBS) is a key deformation mechanism at high homologous temperatures in polycrystalline materials, however, its intrinsic behavior is often obscured by additional strain accommodation processes. In this study, dislocation-mediated unconstrained GBS was investigated using Ni bicrystal micropillars containing a single high-angle grain boundary. Micropillar compression tests were conducted over a temperature range from room temperature to $ 600,^{\circ}\mathrm{C}$ and strain rates between $ 5\times10^{-4}$ and $ 10^{-1},\mathrm{s}^{-1}$ . By comparing bicrystal and single-crystal responses, the intrinsic contribution of GBS was isolated. The strain-rate sensitivity remained low (SRS $ \approx 0.034 \pm 0.017$ ), comparable to room temperature values, indicating the absence of diffusion-controlled accommodation mechanisms. The activation energy for GBS was determined to be $ 234,\mathrm{kJ,mol^{-1}}$ , consistent with grain boundary diffusion-assisted glide of grain boundary dislocations. These results demonstrate that the high strain-rate sensitivity commonly associated with GBS in polycrystals originates primarily from accommodation processes rather than the intrinsic sliding mechanism.
Materials Science (cond-mat.mtrl-sci)
Discharge at the Microscale: Using Optical Tweezers to Observe Muon-Induced Discharges of a Levitated Microparticle in Air
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Andrea Stoellner, Isaac C.D. Lenton, Caroline Muller, Scott Waitukaitis
Electrical discharge at the smallest possible length and charge scales is not well understood. Using optical tweezers, we investigate spontaneous discharges of a single micron-scale particle levitated in air. These ``microdischarges’’ have a typical size of $ \sim$ 40 $ |e|$ , but can be as small as a few $ |e|$ and as large as several hundred. The absence of a well-defined trigger charge and the weak dependence on particle size suggest events are not classical gaseous breakdown. Instead, we show that microdischarge events arise from the rapid capture of ions left in the tracks of nearby passing ionizing radiation. Our results highlight the role of natural ionizing radiation in initiating micron-scale discharges and provide a platform for studying discharge physics in electrode-free environments and at the smallest scales.
Soft Condensed Matter (cond-mat.soft), Atmospheric and Oceanic Physics (physics.ao-ph), Optics (physics.optics), Plasma Physics (physics.plasm-ph)
Formation of photoinduced space-charge field during in-bulk domain creation by femtosecond NIR laser irradiation in MgO:LN crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
I. A. Kipenko (1), D. A. Zorikhin (1), A. R. Akhmatkhanov (1), V. Ya. Shur (1) ((1) Ural Federal University, Yekaterinburg, Russia)
We have studied the domain switching under NIR fs-laser irradiation in MgO:LN single crystals with special attention to the relative positions of the light-induced domains, microtracks and regions with modified refractive index in the vicinity of the focusing point. The optical imaging along X direction of the irradiated sample demonstrated the narrow microtracks and the lens-shaped regions (“lenses”) located in the vicinity of the microtracks. The relative positions of light-induced microtracks, domains and lenses were revealed by overlapping of their images. We have found that the domain envelops the microtrack and partially intersects with the lens. The temperature stability of all light-induced objects during annealing was studied. It was shown that the local modification of the refractive index disappeared irreversibly while the microtrack and domain remain unchanged. The obtained local modification of the refractive index has been considered as a result of the photorefractive effect. The disappearance of the lens after annealing is caused by bulk screening of the photoinduced space-charge field by increased bulk conductivity. The generation of photovoltaic field by tightly focused NIR fs-laser irradiation close to the focusing point is reported for the first time to the authors’ knowledge. It should be noted that in LN the photovoltaic field is codirectional with spontaneous polarization and thus cannot switch the polarization. However, it is possible in ferroelectrics with the opposite direction of the photovoltaic field and low value of threshold field. The revealed effect can be utilized for creation of 3D nonlinear photonic crystals by in-bulk domain engineering.
Materials Science (cond-mat.mtrl-sci)
11 pages, 7 figures
Spinon shift current in a noncentrosymmetric quantum spin chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
Ryosuke Yamashita, Shintaro Takayoshi, Takahiro Morimoto
We theoretically study direct current generation in a quantum spin chain induced by spinon excitations by light irradiation. We consider a s=1/2 1D antiferromagnetic XXZ model with magnetoelectric coupling that describes multiferroics with broken inversion symmetry. We perform the real-time simulation using infinite time-evolving block decimation (iTEBD), and demonstrate the direct current generation under light irradiation. By comparing the second order nonlinear conductivity and the two-spinon excitation spectra of 1D XXZ model, we confirm that the spinon excitations are the origin for the direct current generation in the quantum spin chain. We find that the bulk photovoltaic effect is driven by electric polarization carried by the spinons through the shift current mechanism, and thus is regarded as ``the spinon shift current’’.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 6 figures
Exact Steady State of a One-end Driven XXZ Spin Chain with Boundary Field
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
We find an exact nonequilibrium steady state of an open dissipatively driven XXZ spin-1/2 chain with source or sink spin bath at one end and an arbitrary boundary field at the other end.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
2 pages, no figures
Laser-written reconfigurable energy landscapes and programmable Moiré spin textures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Matteo Panzeri, Piero Florio, Davide Girardi, Joseba Urrestarazu, Giacomo Sala, Nicola Pellizzi, Matteo Vitali, Marco Madami, Luca Ciaccarini Mavilla, Silvia Tacchi, Elisa Riedo, Andrea Meo, Vito Puliafito, Mario Carpentieri, Riccardo Tomasello, Efe Ersoy, Kai Wagner, Patrick Maletinsky, Olivier Boulle, Edoardo Albisetti, Daniela Petti
Magnetic textures are central to emerging spintronic and unconventional computing technologies due to their rich dynamics, topological properties and nanoscale dimensions. A major challenge remains achieving tunable, reversible, and spatially resolved control over these textures and their evolution as a function of external stimuli, by spatially reprogramming the magnetic energy landscape that governs their nucleation and stability. Here, we exploit a focused laser-assisted local field cooling technique that establishes a fast, non-contact and scalable platform for grayscale spin texture engineering. By non-destructively controlling the exchange-bias anisotropy with nanoscale resolution in thin-film heterostructures, this approach enables grayscale, reprogrammable control of the local energy profile, which we use to create magnetic patterns with highly controlled hysteresis, field-dependent readability and tunable switching thresholds. Leveraging this capability, we demonstrate information encoding with magnetic field-gated readability, and artificial spin metamaterials, stabilizing spin lattices with field-reconfigurable symmetries and creating artificial Moiré spin textures via the geometric superposition of twisted magnetic potentials. These results establish a versatile, reprogrammable platform that bridges the gap between application-oriented magnetic memory and fundamental studies of emergent order in artificial lattices.
Materials Science (cond-mat.mtrl-sci)
20 pages, 5 figures and supplementary
Observation of Strong-to-Weak Spontaneous Symmetry Breaking in a Dephased Fermi Gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-04-20 20:00 EDT
Si Wang, Thomas G. Kiely, Dorothee Tell, Johannes Obermeyer, Marnix Barendregt, Petar Bojović, Philipp M. Preiss, Abhijat Sarma, Titus Franz, Matthew P. A. Fisher, Cenke Xu, Immanuel Bloch
Symmetry-based classification of quantum phases of matter is one of the most foundational organizing principles in physics; however, an analogous framework for mixed, decohered quantum states has only begun to emerge. A central new concept is strong-to-weak spontaneous symmetry breaking (SW-SSB), a sharp transition in mixed quantum states that is invisible to any observable linear in the density matrix and that has since been predicted across a broad class of open and monitored quantum systems. It also provides a unifying language for phenomena as disparate as the decodability of topological quantum memories and the emergence of classical hydrodynamics from decohered quantum dynamics. Here we report the first experimental observation of SW-SSB, in dephased single-component fermionic matter imaged by a quantum gas microscope. A quantum-classical estimator built on a machine-learned Gaussian reference state gives direct access to the nonlinear Rényi-1 and Rényi-2 correlators that diagnose SW-SSB, and reveals long-range Rényi order in the dephased Fermi liquid. Adding a commensurate superlattice drives the underlying fermions through a metal-to-insulator transition that, after full dephasing, manifests as a sharp SW-SSB phase transition. Our results uncover the symmetry principle behind information-theoretic transitions in open quantum systems, and extend Landau’s symmetry paradigm into the regime of real, decohering quantum devices.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Hopping-Mediated Charge Transport in Graphene Beyond the Ballistic Regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
J. P. Dadario Pereira, Raphael Tromer, Luiz A. Ribeiro Junior, Douglas S. Galvao
We present a trajectory-resolved framework for charge transport in graphene and related two-dimensional carbon systems beyond the ideal ballistic and fully coherent limits. Transport is described by kinetic Monte Carlo hopping on a predefined atomic lattice, allowing the combined treatment of disorder, thermal activation, and external fields. Current and effective transmittance are extracted directly from stochastic carrier trajectories, without phenomenological transport coefficients.
We apply the method to graphene under bias voltage (0-0.10 V), temperature (300-900 K), magnetic field (0-10 T), in-plane strain (2-10%, uniaxial and biaxial), and vacancy concentration (0-10%). Pristine graphene shows an almost ohmic response, with currents of about 7-8 uA, effective transmittance near 0.98-1.00, and conductance of about (5.8-7.8) x 10^-5 S at 0.10 V, depending on direction. Vacancies strongly suppress transport, reducing transmittance to about 0.45-0.75 at 10% vacancy. Higher temperature accelerates hopping and partly restores transport, but cannot overcome severe connectivity loss. Magnetic fields further reduce transport, especially in disordered networks. The framework provides a unified computational scheme for realistic two-dimensional carbon materials and also yields diffusion coefficients and effective mobilities from carrier displacements and transit times.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Spinning Living Crystals of Run-and-Tumble Particles with Environmental Feedback
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Maks Pečnik Bambič, Nuno A. M. Araújo, Giorgio Volpe
Collective rotations are common in active matter, enhancing cohesion, transport, and mixing. They are typically attributed to chiral non-reciprocal dynamics due to intrinsic particle chirality, torque-generating interactions among units, or geometric confinement. Here, we uncover a different mechanism for rotational order in active matter where a dynamic environment coordinates the self-organization of non-chiral active particles into living crystals exhibiting sustained collective solid-like rotations. At intermediate densities, feedback from a fluctuating landscape of passive Brownian particles stabilizes large living crystals of obstacle-avoiding run-and-tumble agents. Strikingly, this environmental feedback also produces living crystals with qualitatively distinct dynamics: collective solid-like spinning emerges for particles with long persistence times approaching ballistic motion, rather than for particles moving by conventional enhanced diffusion. Beyond revealing a new route to collective rotational order in active matter, these findings highlight the integral role of a dynamic environment in self-organization and suggest environment-mediated design principles for active materials with unconventional dynamical responses.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
23 pages, 17 figures
Environmental Control of Self-Aligning Chiral Bristlebots
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Timo Wagner, Michael Himpel, Thomas Ihle, Horst-Holger Boltz
Active matter systems characterized by the interplay of chirality and self-alignment offer a rich landscape for the emergence of non-equilibrium collective behaviors and the development of autonomous materials. We present a versatile experimental platform for studying these dynamics using augmented commercial bristlebots, where custom-designed housings and elastic couplings induce a self-aligning torque and a stable chiral drift. By mapping experimental trajectories to a Langevin-type model, we characterize the single-particle dynamics. In circular geometries, we show that the stability of edge currents is governed by the interaction between intrinsic particle chirality and handedness of the edge current. Furthermore, we demonstrate that transport can be geometrically rectified using a nautilus-shaped obstacle, which acts as a doubly chirality-sensitive ratchet. Finally, we explore the collective dynamics of rigidly linked assemblies, observing spontaneous mode-switching between translational and rotational states in triangular active solids. Our results provide a robust framework for the passive control of active gases and illustrate how geometric constraints can be used to program complex transport properties in synthetic active systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
main manuscript: 8 pages, 5 figures; supplemental: 8 pages, 7 figures
ChemGraph-XANES: An Agentic Framework for XANES Simulation and Analysis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Vitor F. Grizzi, Thang Duc Pham, Luke N. Pretzie, Jiayi Xu, Murat Keceli, Cong Liu
Computational X-ray absorption near-edge structure (XANES) is widely used to probe local coordination environments, oxidation states, and electronic structure in chemically complex systems. However, the use of computational XANES at scale is constrained more by workflow complexity than by the underlying simulation method itself. To address this challenge, we present ChemGraph-XANES, an agentic framework for automated XANES simulation and analysis that unifies natural-language task specification, structure acquisition, FDMNES input generation, task-parallel execution, spectral normalization, and provenance-aware data curation. Built on ASE, FDMNES, Parsl, and a LangGraph/LangChain-based tool interface, the framework exposes XANES workflow operations as typed Python tools that can be orchestrated by large language model (LLM) agents. In multi-agent mode, a retrieval-augmented expert agent consults the FDMNES manual to ground parameter selection, while executor agents translate user requests into structured tool calls. We demonstrate documentation-grounded parameter retrieval and show that the same workflow supports both explicit structure-file inputs and chemistry-level natural-language requests. Because independent XANES calculations are naturally task-parallel, the framework is well suited for high-throughput deployment on high-performance computing (HPC) systems, enabling scalable XANES database generation for downstream analysis and machine-learning applications. ChemGraph-XANES thus provides a reproducible and extensible workflow layer for physics-based XANES simulation, spectral curation, and agent-compatible computational spectroscopy.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Chemical Physics (physics.chem-ph)
Bridging Atomistic and Continuum Descriptions of Nanoscale Dislocation Loops in Tungsten
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Joseph Duque Lopez, Sergei Dudarev, James Kermode, Thomas Hudson
In order to predict the long-term effects of irradiation on the material properties of tungsten, a continuum approach to simulating the interactions of dislocation loops, which arise from radiation damage, is proposed. Continuum models of the displacement, strain and stress fields produced by dislocation loops exhibit unphysical singularities near the defect core, but are thought to accurately capture atomistic displacements in the far-field. A linear elastic model of nanoscale dislocation loops in tungsten is developed, and the model is verified using atomistic simulations to ensure that the model is informed by lower-length scale phenomena such that the physics of the problem is correctly captured. We discuss the model and its advantages, and show that predictions produced by atomistic simulations do indeed agree well with the far-field behaviour of the continuum model when dislocation loops are far from material boundaries. In particular, we robustly demonstrate that the decay rate of atomistic results and continuum results coincide with one another, and show that the results converge as the size of the atomistic simulations approach the far-field limit.
Materials Science (cond-mat.mtrl-sci)
MF-toolkit: A High-Performance Python Library for Multifractal Analysis with Automated Crossover Detection, Source Identification and Application to Gravitational Waves Data
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-04-20 20:00 EDT
Nahuel Mendez, Maria Cristina Mariani Maria Pia Beccar-Varela, Osei Tweneboah, Sebastian Jaroszewicz
Multifractal Detrended Fluctuation Analysis (MFDFA) is a powerful and widely used technique for characterizing the scaling properties and long-range correlations of complex time series. However, its application often involves significant practical challenges, such as the subjective identification of scaling regions (crossovers) and the disambiguation of the physical origins of multifractality. We introduce MF-toolkit, a high-performance, parallelized Python library designed to address these challenges. It integrates three key innovations: (1) fully automatic crossover detection algorithms (CDV-A and SPIC), which remove operator bias and enhance reproducibility; (2) a built-in implementation of the Iterative Amplitude Adjusted Fourier Transform (IAAFT) for generating surrogate data, enabling the robust identification of the source of multifractality; and (3) a comprehensive suite for generating synthetic time series for rigorous validation. We demonstrate the rigor and utility of MF-toolkit through its application to characterize the multifractal properties of non-stationary noise in gravitational wave (LIGO) data. The MF-toolkit library offers a robust, efficient, and user-friendly tool for advanced time series analysis, facilitating more rigorous and reproducible research across physics and other data-intensive fields.
Statistical Mechanics (cond-mat.stat-mech), General Relativity and Quantum Cosmology (gr-qc)
This is the same manuscript available at SSRN: this https URL or this http URL
Atomistic Mechanisms of Stress-Dependent Molten Salt Corrosion in NiCr Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-04-20 20:00 EDT
Hamdy Arkoub, Jia-Hong Ke, Miaomiao Jin
Ni-based structural alloys in molten salt environments often experience simultaneous mechanical loading and corrosive attack, yet the mechanisms governing stress-corrosion interactions remain unclear. Prior studies largely emphasize tensile stress, while the role of compressive stress has received limited attention. Here, reactive molecular dynamics simulations are used to investigate the coupled effects of applied strain and corrosion in Ni$ _{0.75}$ Cr$ _{0.25}$ exposed to molten FLiNaK at 800$ ^\circ$ C. A $ \Sigma5(210)$ grain boundary model is subjected to tensile (+4%) to compressive (-4%) uniaxial strains, and corrosion behavior is evaluated through fluorine adsorption, charge redistribution, and grain boundary evolution. Tensile strain accelerates intergranular corrosion by reducing local atomic packing through elastic dilation and increasing excess free volume at the grain boundary, which enhances atomic mobility and salt infiltration. In contrast, compressive strain suppresses corrosion by promoting the formation of a ridge-like surface layer along the grain boundary, limiting salt access to the underlying alloy. These results provide atomistic insight into how stress states influence grain boundary corrosion in molten salts.
Materials Science (cond-mat.mtrl-sci)
5 figures
Improved Desalination by Polymer Grafting
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-04-20 20:00 EDT
Mamta Yadav, Clifford E. Woodward, Jan Forsman
Freshwater scarcity demands desalination technologies that are efficient, scalable, and sustainable. Capacitive deionisation (CDI) is promising but remains limited by inefficient ion adsorption and poor charge utilisation. Here, we show that suitably chosen polyampholytic block copolymer grafting can substantially enhance CDI performance, via a combination of dipolar response and steric effects. Using mean-field classical density functional theory and grand-canonical Monte Carlo simulations, we demonstrate that such polymer grafted electrodes enable strongly improved desalination performance, without altering the pore architecture. Even an electrode grafting by simple neutral polymers can generate an improvement, although a suitably designed block polymer architecture offers an additional performance gain. These results establish interfacial block copolymer grafting as a powerful route toward high-performance, membrane-free desalination.
Soft Condensed Matter (cond-mat.soft)
10 Figures
Benchmarking Current-to-Voltage Amplifiers for Quantum Transport Measurements
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-04-20 20:00 EDT
J. Escorza, G. Pellicer, T. de Ara, J. Hurtado-Gallego, E. Scheer, C. Untiedt, C. Sabater
Accurate electrical amplification is essential in molecular electronics for measuring conductance through atomic and molecular junctions, where currents often span several orders of magnitude. In this work, we present a systematic design and comparative analysis of four current-to-voltage ($ I\text{–}V$ ) amplifier architectures: single-stage linear, series-linear, logarithmic, and multi-stage cascaded, specifically optimized for break junction (BJ) techniques, including scanning tunneling microscopy (STM-BJ) and mechanically controllable break junctions (MCBJ). Each configuration is evaluated based on sensitivity, noise performance, and dynamic range. Our results characterize the trade-offs between circuit complexity and noise, providing a robust framework and practical guidelines for selecting amplification schemes in quantum transport experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Main text and Supplemental Material (18 pages, 21 figures)
Renormalised thermodynamics for Bose gases from low to critical temperatures
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-04-20 20:00 EDT
Michael H. Heinrich, Alexander Wowchik, Jürgen Berges
We compute thermodynamic properties of dilute Bose gases using non-perturbative approximations of the two-particle irreducible (2PI) effective action. It is shown how to systematically renormalise the self-consistent descriptions beyond conventional Gaussian approximations such as Hartree-Fock-Bogoliubov theory. This allows us to determine the condensate depletion from low to high temperatures, including its critical behaviour at the phase transition. While the universal anomalous dimension at criticality is vanishing for Gaussian approximations, we determine its non-zero value at next-to-leading order of a self-consistent expansion in the number of field components.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
18 pages, 4 figures
Fluctuating Pair Density Wave in Finite-temperature Phase Diagram of the $t$-$t^\prime$ Hubbard Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-04-20 20:00 EDT
The Hubbard model and its extensions are canonical theoretical frameworks for understanding correlated electronic states, including those in high-$ T_c$ cuprates. Here, we use state-of-the-art thermal tensor network method to map out the temperature-doping phase diagram of the $ t$ -$ t^\prime$ Hubbard model. On the electron-doped side, we find a $ d$ -wave superconducting (dSC) regime, supporting the scenario of high-$ T_c$ superconductivity. In contrast, on the hole-doped side, no robust dSC phase is detected. Instead, a finite-temperature regime dominated by strong pair-density-wave (PDW) fluctuations emerges, which may eventually give way to charge density wave order upon further cooling. The PDW state exhibits inter-arc pairing with net momentum near $ (0, \pi)$ , distinct from the zero-momentum pairing in conventional dSC. Furthermore, these fluctuating PDW states occupy the lower portion of the pseudogap regime on the hole-doped side. We provide a comprehensive finite-temperature perspective consistent with previous ground-state studies, shedding new light on pairing instabilities and exotic electronic states in high-$ T_c$ superconductors.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
9+8 pages, 7+9 figures. Comments are welcome