CMP Journal 2025-06-13
Statistics
Physical Review Letters: 15
Review of Modern Physics: 1
arXiv: 64
Physical Review Letters
Emergent Equilibrium in All-Optical Single Quantum-Trajectory Ising Machines
Research article | Bifurcations | 2025-06-12 06:00 EDT
Jacopo Tosca, Marcello Calvanese Strinati, Claudio Conti, and Cristiano Ciuti
We investigate the dynamics of multimode optical systems driven by two-photon processes and subject to nonlocal losses, incorporating quantum noise at the Gaussian level. Our findings show that the statistics retrieved from a single Gaussian quantum trajectory exhibits emergent thermal equilibrium governed by an Ising Hamiltonian, encoded in the dissipative coupling between modes. The system’s effective temperature is set by the driving strength relative to the oscillation threshold. Given the ultrashort timescales typical of all-optical devices, our Letter demonstrates that such multimode optical systems can operate as ultrafast Boltzmann samplers, paving the way toward the realization of efficient hardware for combinatorial optimization, with promising applications in machine learning and beyond.
Phys. Rev. Lett. 134, 230404 (2025)
Bifurcations, Dynamics of nonlinear optical systems, Open quantum systems, Quantum optics, Quantum simulation, Quantum stochastic processes, Ising model
Single-Qubit Gates with Errors at the ${10}^{- 7}$ Level
Research article | Atom & ion trapping & guiding | 2025-06-12 06:00 EDT
M. C. Smith, A. D. Leu, K. Miyanishi, M. F. Gely, and D. M. Lucas
We report the achievement of single-qubit gates with sub-part-per-million error rates, in a trapped-ion $^{43}{\mathrm{Ca}}^{+}$ hyperfine clock qubit. We explore the speed and fidelity trade-off for gate times $4.4\le {t}{g}\le 35\text{ }\text{ }\mathrm{\mu }\mathrm{s}$, and benchmark a minimum error per Clifford gate of $1.5(4)\times{}{10}^{- 7}$. Calibration errors are suppressed to $<{10}^{- 8}$, leaving qubit decoherence (${T}{2}\approx 70\text{ }\text{ }\mathrm{s}$), leakage, and measurement as the dominant error contributions. The ion is held above a microfabricated surface-electrode trap that incorporates a chip-integrated microwave resonator for electronic qubit control; the trap is operated at room temperature without magnetic shielding.
Phys. Rev. Lett. 134, 230601 (2025)
Atom & ion trapping & guiding, Quantum algorithms & computation, Quantum benchmarking, Quantum coherence & coherence measures, Quantum control, Quantum gates, Qubits, Trapped ions
Entangling Two Rydberg Superatoms via Heralded Storage
Research article | Quantum engineering | 2025-06-12 06:00 EDT
Zi-Ye An, Bo-Wei Lu, Jun Li, Chao-Wei Yang, Li Li, Xiao-Hui Bao, and Jian-Wei Pan
Using Rydberg superatoms, an experiment demonstrates the heralded photon storage and remote entanglement without the need for an intermediate node.
Phys. Rev. Lett. 134, 230803 (2025)
Quantum engineering, Quantum memories, Quantum networks, Quantum optics, Quantum repeaters, Quantum state transfer, Rydberg gases
Magnets are Weber Bar Gravitational Wave Detectors
Research article | Gravitational wave detection | 2025-06-12 06:00 EDT
Valerie Domcke, Sebastian A. R. Ellis, and Nicholas L. Rodd
When a gravitational wave (GW) passes through a dc magnetic field, it couples to the conducting wires carrying the currents which generate the magnetic field, causing them to oscillate at the GW frequency. The oscillating currents then generate an ac component through which the GW can be detected—thus forming a resonant mass detector or a nagnetic Weber bar. We quantify this claim and demonstrate that magnets can have exceptional sensitivity to GWs over a frequency range demarcated by the mechanical and electromagnetic resonant frequencies of the system; indeed, we outline why a magnetic readout strategy can be considered an optimal Weber bar design. The concept is applicable to a broad class of magnets, but can be particularly well exploited by the powerful magnets being deployed in search of axion dark matter, for example, by DMRadio and ADMX-EFR. Explicitly, we demonstrate that the MRI magnet that is being deployed for ADMX-EFR can achieve a broadband GW strain sensitivity of $\sim {10}^{- 20}/\sqrt{\mathrm{Hz}}$ from a few kHz to about 10 MHz, with a peak sensitivity down to $\sim {10}^{- 22}/\sqrt{\mathrm{Hz}}$ at a kHz exploiting a mechanical resonance.
Phys. Rev. Lett. 134, 231401 (2025)
Gravitational wave detection, Axions, Gravitational wave detectors
Low Energy Limit of Banks-Fischler-Shenker-Susskind Quantum Mechanics
Research article | Supergravity | 2025-06-12 06:00 EDT
Óscar J. C. Dias and Jorge E. Santos
We investigate the low energy regime of BFSS quantum mechanics using its holographic dual. We identify three distinct thermodynamic phases (black holes) and analyze their thermodynamic properties extensively, including phase transitions amongst the several phases. While the properties of the canonical ensemble aligns with existing conjectures on BFSS thermodynamics, we uncover intriguing and unexpected behavior in the microcanonical ensemble. Specifically, for sufficiently low energies, we observe the dominance of the localized phase. Surprisingly, we also identify an energy range where the non-uniform phase becomes dominant. The transition between these phases is mediated by a Kol-type topology-changing phenomenon.
Phys. Rev. Lett. 134, 231402 (2025)
Supergravity, Classical black holes, Quantum aspects of black holes, Numerical relativity, Numerical simulations in gravitation & astrophysics
Effective Action for Relativistic Hydrodynamics from the Crooks Fluctuation Theorem
Fluctuation theorems | 2025-06-12 06:00 EDT
Nicki Mullins, Mauricio Hippert, and Jorge Noronha
A new effective theory framework for fluctuating hydrodynamics in the relativistic regime is derived using standard thermodynamical principles and general properties of nonequilibrium stochastic dynamics. For the first time, we establish clear and concise conditions for ensuring that the resulting effective theories are causal, stable, and well-posed within general relativity. These properties are independent of spacetime foliation and are valid in the full nonlinear regime. Out-of-equilibrium fluctuations are constrained by a relativistically covariant version of the Crooks fluctuation theorem, which determines how the entropy production is distributed even when the system is driven by an external force. This leads to an emerging ${\mathbb{Z}}_{2}$ symmetry responsible for imposing fluctuation-dissipation relations for n-point correlation functions, which matches the standard constraints for the Schwinger-Keldysh effective action.
Phys. Rev. Lett. 134, 232302 (2025)
Fluctuation theorems, Relativistic heavy-ion collisions, Stochastic dynamical systems, Relativistic hydrodynamics
Seniority Structure in Neutron-Rich Nucleus $^{128}\mathrm{Ag}$: Evidence for Robustness of $N=82$ Shell Closure in Silver Isotopes
Research article | Isomer decays | 2025-06-12 06:00 EDT
D. W. Luo et al.
The spectroscopic studies of very neutron-rich nucleus $^{128}\mathrm{Ag}$ have been performed for the first time at the Radioactive Isotope Beam Factory of RIKEN. A new seniority isomer with a half-life of $1.60(7)\text{ }\text{ }\mathrm{\mu }\mathrm{s}$ has been identified and is proposed to have a spin-parity of ${16}^{- }$ with a maximally aligned configuration comprising three proton holes in the ${g}{9/2}$ orbital and one neutron hole in the ${h}{11/2}$ orbital. The new level structure in $^{128}\mathrm{Ag}$ is quite well described by shell model calculations without invoking excitations across the $Z=50$ and $N=82$ shell gaps, and presents a good case of seniority scheme in odd–odd nuclei in the south vicinity of the double-magic nucleus $^{132}\mathrm{Sn}$. With a classification of various components of the proton–neutron interaction, the inversion of lowest-lying ${9}^{- }$ and ${10}^{- }$ states between $^{128}\mathrm{Ag}$ and its neighboring isotone $^{130}\mathrm{In}$ is found to be dynamically ascribed to the seniority-nonconserving proton–neutron interaction components. The structure above ${10}^{- }$ up to the ${16}^{- }$ isomer in $^{128}\mathrm{Ag}$ shows remarkable similarities to seniority structures in the semimagic nuclei $^{128}\mathrm{Pd}$ and $^{130}\mathrm{Cd}$. These spectroscopic features in $^{128}\mathrm{Ag}$ indicate that the $N=82$ shell closure is still robust in silver isotopes.
Phys. Rev. Lett. 134, 232502 (2025)
Isomer decays, Nuclear structure & decays, Shell model, 90 ≤ A ≤ 149, Radioactive beams
Spatiotemporal Energy Cascade in Three-Dimensional Magnetohydrodynamic Turbulence
Research article | Magnetohydrodynamic turbulence | 2025-06-12 06:00 EDT
Giuseppe Arrò, Hui Li, and William H. Matthaeus
We present a new scale decomposition method to investigate turbulence in wavenumber-frequency space. Using 3D magnetohydrodynamic turbulence simulations, we show that magnetic fluctuations with time scales longer than the nonlinear time exhibit an inverse cascade toward even smaller frequencies. Low frequency magnetic fluctuations support turbulence, acting as an energy reservoir that is converted into plasma kinetic energy, the latter cascading toward large wavenumbers and frequencies, where it is dissipated. Our results shed new light on the spatiotemporal properties of turbulence, potentially explaining the origin and role of low frequency turbulent fluctuations in the solar wind.
Phys. Rev. Lett. 134, 235201 (2025)
Magnetohydrodynamic turbulence, Plasma turbulence
Real-Time 3D Coherent X-Ray Diffraction Imaging
Research article | Structural properties | 2025-06-12 06:00 EDT
Fangzhou Ai, Oleg Shpyrko, and Vitaliy Lomakin
The coherent x-ray diffraction imaging (CXDI) technique offers unique insights into the nanoscale world, enabling the reconstruction of 3D structures with a nanoscale resolution achieved through computational phase reconstruction from measured scattered intensity maps. However, the computational demands of 3D coherent x-ray diffraction imaging limit its real-time application in experimental settings. This Letter presents a carousel phase retrieval algorithm (CPRA) that enables the real-time, high-resolution reconstruction of computationally complex 3D objects. CPRA is based on representing the 3D reconstruction problem as a set of 2D reconstructions of projected images corresponding to different experimentally collected angles via the Fourier slice theorem. The consistency between the 2D reconstructed images is based on an iterative procedure in which each 2D reconstruction accounts for the adjacent 2D reconstructed images in a periodic (carousel) manner. Demonstrations on complex systems, including a lithium-rich layered oxide particle and a biological cell of Staphylococcus aureus, demonstrate that CPRA significantly enhances the reconstruction quality and enables the reconstruction process to be completed in real time during the experiment.
Phys. Rev. Lett. 134, 236202 (2025)
Structural properties, X-ray diffraction, X-ray imaging
Quasi-1D Coulomb Drag in the Nonlinear Regime
Research article | Mesoscopics | 2025-06-12 06:00 EDT
Mingyang Zheng, Rebika Makaju, Rasul Gazizulin, Alex Levchenko, Sadhvikas J. Addamane, and Dominique Laroche
One-dimensional Coulomb drag has been an essential tool to probe the physics of interacting Tomonaga-Luttinger liquids. To date, most experimental work has focused on the linear regime while the predictions for Luttinger liquids beyond the linear response theory remain largely untested. In this Letter, we report measurements of reciprocal momentum transfer induced Coulomb drag between vertically coupled quasi-one-dimensional quantum wires in the nonlinear regime. Measurements were performed at ultralow temperatures between wires only 15 nm apart. Our results reveal a nonlinear dependence of the drag voltage as a function of the drive current superimposed with an oscillatory contribution, in agreement with theoretical predictions for Coulomb drag between Tomonaga-Luttinger liquids. Additionally, the observed current-voltage characteristics exhibit a nonmonotonic temperature dependence, further corroborating the presence of non-Fermi-liquid behavior in our system. These findings are observed both in the single and in the multiple subband regimes and in the presence of disorder, extending the onset of this behavior beyond the clean single channel Tomonaga-Luttinger regime where the predictions were originally formulated.
Phys. Rev. Lett. 134, 236301 (2025)
Mesoscopics, Quantum transport, Transport phenomena, 1-dimensional systems, Devices, III-V semiconductors, Quantum wires, Luttinger liquid model
Tunable $t- {t}^{‘ }- U$ Hubbard Models in Twisted Square Homobilayers
Research article | Flat bands | 2025-06-12 06:00 EDT
P. Myles Eugenio, Zhu-Xi Luo, Ashvin Vishwanath, and Pavel A. Volkov
Square lattice Hubbard model with tunable hopping ratio ${t}^{‘ }/t$ is highly promising for realizing a variety of quantum phases, including higher-temperature superconductivity. We show that twisted square lattice homobilayers offer such tunability when the flat bands originate from the corner of the Brillouin zone. An emergent symmetry, generically present at low twist angles, enforces $t=0$ for these bands. Breaking it with interlayer displacement field or in-plane magnetic field introduces $t$ and anisotropy, tunable in a wide range for correlated electrons on the moir'e square lattice.
Phys. Rev. Lett. 134, 236503 (2025)
Flat bands, Phase diagrams, Twistronics, 2-dimensional systems, Strongly correlated systems, Lattice models in condensed matter, Symmetries in condensed matter, Tight-binding model, k dot p method
Instanton-Induced Supersymmetry Breaking in Topological Semimetals
Research article | Spontaneous symmetry breaking | 2025-06-12 06:00 EDT
W. B. Rui, Y. X. Zhao, and Z. D. Wang
Supersymmetry (SUSY) proposed as an elementary symmetry for physics beyond the standard model has found important applications in various areas outside high-energy physics. Here, we systematically implement supersymmetric quantum mechanics—exhibiting fundamental SUSY properties in the simple setting of quantum mechanics—into a wide range of topological semimetals, where the broken translational symmetry, e.g., by a magnetic field, is effectively captured by a SUSY potential. We show that the dynamical SUSY breaking via the instanton effect over the SUSY potential valleys works as the underlying mechanism for the gap opening of the topological semimetallic phases, and the magnitude of the instanton effect is proportional to the energy gap. This instanton mechanism provides a simple criterion for determining whether the energy gap has been opened, without resorting to detailed calculations, i.e., a finite energy gap is opened if and only if the SUSY potential has an even number of zeros. Our theory leads to previously unexpected results: even an infinitesimal magnetic field can open a gap in topologically robust Dirac, Weyl, and nodal-line semimetallic phases due to the dynamical SUSY breaking. Overall, the revealed connection between SUSY quantum mechanics and nonuniform topological semimetals can elucidate previously ambiguous phenomena, provide guidance for future investigations, and open a new avenue for exploring topological semimetals.
Phys. Rev. Lett. 134, 236602 (2025)
Spontaneous symmetry breaking, Supersymmetric models, Topological phases of matter, Dirac semimetal, Node-line semimetals, Topological materials, Weyl semimetal, Supersymmetry, Band structure methods, Chiral symmetry
Direct Evidence for Anisotropic Magnetic Interaction in $\alpha \text{- }{\mathrm{RuCl}}_{3}$ from Polarized Inelastic Neutron Scattering
Research article | Magnetic anisotropy | 2025-06-12 06:00 EDT
Markus Braden, Xiao Wang, Alexandre Bertin, Paul Steffens, and Yixi Su
Polarized inelastic neutron scattering reveals clear evidence for bond-directional anisotropy that fully modifies the anisotropic magnon dispersion in α-RuCl3.
Phys. Rev. Lett. 134, 236702 (2025)
Magnetic anisotropy, Magnetic interactions, Magnetism, Spin dynamics
Field-Free Superconducting Diode Effect in Layered Superconductor FeSe
Research article | Non-reciprocal propagation | 2025-06-12 06:00 EDT
Utane Nagata, Motomi Aoki, Akito Daido, Shigeru Kasahara, Yuichi Kasahara, Ryo Ohshima, Yuichiro Ando, Youichi Yanase, Yuji Matsuda, and Masashi Shiraishi
The superconducting diode effect (SDE), where zero-resistance states appear nonreciprocally during current injection, is receiving tremendous interest in both fundamental and applied physics because the SDE is a novel manifestation of symmetry breaking and enables the creation of a novel diode. In particular, magnetic-field-free SDEs have been extensively investigated because of their potential to serve as building blocks for superconducting circuit technology. In this Letter, we report the field-free SDE in a layered superconductor, FeSe. Its underlying physics is clarified by systematic controlled experiments to be an interplay of a large thermoelectric response and geometrical asymmetry in FeSe. Our findings can pave a new avenue for the construction of novel material and device platforms utilizing SDEs.
Phys. Rev. Lett. 134, 236703 (2025)
Non-reciprocal propagation, Rashba coupling, Superconducting devices
Coherent Interaction of $2s$ and $1s$ Exciton States in Transition-Metal Dichalcogenide Monolayers
Research article | Biexcitons | 2025-06-12 06:00 EDT
Max Wegerhoff, Moritz Scharfstädt, Stefan Linden, and Andrea Bergschneider
We use femtosecond pump-probe spectroscopy to study the coherent interaction of excited exciton states in ${\mathrm{WSe}}{2}$ and ${\mathrm{MoSe}}{2}$ monolayers via the optical Stark effect. For cocircularly polarized pump and probe, we measure a blueshift that points to a repulsive interaction between the $2s$ and $1s$ exciton states. The determined $2s\text{- }1s$ interaction strength is on par with that of the $1s\text{- }1s$ in agreement with the semiconductor Bloch equations. Furthermore, we demonstrate the existence of a $2s\text{- }1s$ biexciton bound state in the cross-circular configuration in both materials and determine their binding energy.
Phys. Rev. Lett. 134, 236901 (2025)
Biexcitons, Excitons, Stark effect, Valley degrees of freedom, Layered semiconductors, Transition metal dichalcogenides, Pump-probe spectroscopy
Review of Modern Physics
Universality in driven open quantum matter
Research article | Open quantum systems & decoherence | 2025-06-12 06:00 EDT
Lukas M. Sieberer, Michael Buchhold, Jamir Marino, and Sebastian Diehl
Driven open many-body quantum systems give rise to nonequilibrium stationary states through the interplay of unitary Hamiltonian dynamics and dissipation, a key feature of modern experiments on light-driven solids and atomic ensembles. This review explores the different types of universal behavior that emerge in these states and their theoretical classification within nonequilibrium quantum field theory, emphasizing the role of symmetry, topology, and quantum state purity.
Rev. Mod. Phys. 97, 025004 (2025)
Open quantum systems & decoherence, Phase transitions, Renormalization, Dynamic critical phenomena, Many-body techniques
arXiv
Magnetophoresis of Weakly Magnetic Nanoparticle Suspension Around a Wire
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Mohd Bilal Khan, Peter Rassolov, Jamel Ali, Theo Siegrist, Munir Humayun, Hadi Mohammadigoushki
We present a combined experimental and numerical study into the magnetophoresis behavior of weakly magnetic nanoparticle suspensions in the vicinity of a wire under a non-uniform magnetic field and negligible inertia. The experiments were conducted within a closed rectangular cuvette, with a wire positioned between the poles of an electromagnet. Two types of nanoparticles, paramagnetic manganese oxide and diamagnetic bismuth oxide, were studied across a broad range of concentrations (10-100 mgL), magnetic field strengths (0.25-1 T), and wire diameters (0.8-3.17 mm). Our experimental findings reveal that upon the application of a magnetic field, paramagnetic nanoparticles experience a strong, attractive force toward the wire periphery. This force generates vortices and secondary flows around the wire, depleting particles from the bulk of the cuvette and concentrating them near the wire surface. The magnetophoresis dynamics of paramagnetic nanoparticles are shown to scale with their initial concentration, wire diameter, and the strength of the external magnetic field. In contrast, diamagnetic nanoparticles exhibit markedly different behavior, with their magnetophoresis dynamics showing minimal dependence on initial concentration and magnetic field strength, while being inversely proportional to the wire diameter. Multiphysics numerical simulations complement the experimental observations, revealing the formation of field-induced particle clusters in weakly paramagnetic nanoparticles, which enhance magnetophoresis. Additionally, the critical magnetic field threshold for the onset of cluster formation is found to be lower than those predicted by theoretical models for clustering in uniform magnetic fields. Under specific conditions, including high magnetic field strengths and elevated nanoparticle concentrations, diamagnetic nanoparticles appear to undergo field-induced clustering.
Materials Science (cond-mat.mtrl-sci)
Spatially Local Estimates of the Thermal Conductivity of Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
C. Ugwumadu, A. Gautam, Y. G. Lee, D. A. Drabold
In this paper we describe a spatial decomposition of the thermal conductivity, what we name “site-projected thermal conductivity”, a gauge of the thermal conduction activity at each site. The method is based on the Green-Kubo formula and the harmonic approximation, and requires the force-constant and dynamical matrices and of course the structure of a model sitting at an energy minimum. Throughout the paper, we use high quality models previously tested and compared to many experiments. We discuss the method and underlying approximations for amorphous silicon, carry our detailed analysis for amorphous silicon, then examine an amorphous-crystal silicon interface, and representative carbon materials. We identify the sites and local structures that reduce heat transport, and quantify these (estimate the spatial range) over which these “thermal defects” are effective. Similarities emerge between these filamentary structures in the amorphous silicon network which impact heat transport, electronic structure (the Urbach edge) and electronic transport.
Materials Science (cond-mat.mtrl-sci)
Manuscript: 18 pages & 11 figures; Supplementary Material: 7 figures
Apparent bistability from weak long-range interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-13 20:00 EDT
Achilleas Lazarides, Andrea Pizzi
Bistability, or the coexistence of two stable phases, can be broken by a bias field $ h$ destabilising one of the phases via the nucleation and growth of defects. Strong long-range interactions, $ 1/r^\alpha$ with $ \alpha$ less than the system’s dimensionality $ d$ , can suppress the proliferation of defects and restore bistability. The case of weak long-range interactions $ d<\alpha < d+1$ remains instead poorly understood. Here, we show that it supports \emph{apparent} bistability: While the system has in principle a unique stable phase, it appears bistable for all practical purposes for $ \alpha < \alpha_c$ , with $ \alpha_c > d$ behaving like a genuine critical point. At the core of this is an exponential scaling of the critical droplet size $ R_c\sim h^{-1/(\alpha - d)}$ , which makes nucleating destabilizing droplets extremely unlikely for $ \alpha < \alpha_c$ , and such that $ \alpha_c$ is mostly independent of system size. In support of these conclusions we provide field-theoretical arguments and numerics on a probabilistic cellular automaton. Overall, our results offer a way to rethink phase stability in systems with long-range interactions as well as a new route to achieve practical bistability.
Statistical Mechanics (cond-mat.stat-mech)
Interacting Electronic Topology of Nonlocal Crystals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Shu Hamanaka, Martina O. Soldini, Tsuneya Yoshida, Titus Neupert
Nonlocal crystals are systems with translational symmetry but arbitrary range couplings or interactions between degrees of freedom. We argue that the notion of topology in such systems does not collapse to that in zero dimensions, as one may naively expect in view of the infinite interaction range. At the same time, we show that the range of available topological phases can be enriched in comparison to the case with local interactions. This is demonstrated by constructing an example of a fermionic symmetry-protected phase in one dimension in symmetry class AII with inversion symmetry, using a Hatsugai-Kohmoto-type model. The new phase exists only in a nonlocal crystal with electron-electron interactions and can be identified from symmetry eigenvalues. We construct an associated topological charge pump as a physical manifestation of its topology.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7+12 pages, 2+2 figures
Entanglement Holography in Quantum Phases via Twisted Rényi-N Correlators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Pablo Sala, Frank Pollmann, Masaki Oshikawa, Yizhi You
We introduce a holographic framework for the entanglement Hamiltonian in symmetry-protected topological (SPT) phases with area-law entanglement, whose reduced density matrix $ \rho \propto e^{-H_e}$ can be treated as a lower-dimensional mixed state. By replicating $ \rho$ , we reconstruct the fixed-point SPT wavefunction, establishing an exact correspondence between the bulk strange correlator of the (d+1)-dimensional SPT state and the twisted Rényi-N operator of the d-dimensional reduced density matrix. Notably, the reduced density matrix exhibits long-range or quasi-long-range order along the replica direction, revealing a universal entanglement feature in SPT phases. As a colloary, we generalized the framework of twisted Rényi-N correlator to thermal states and open quantum systems, providing an alternative formulation of the Lieb-Schultz-Mattis theorem, applicable to both closed and open systems. Finally, we extend our protocol to mixed-state SPT phases and introduce new quantum information metrics – twisted Rényi-N correlators of the surgery operator – to characterize the topology of mixed states.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 11 figures
Worldline deconfinement and emergent long-range interaction in entanglement Hamiltonian and entanglement spectrum
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Zenan Liu, Zhe Wang, Dao-Xin Yao, Zheng Yan
When a system exhibits a bulk gap but gapless edge states (e.g., a symmetry-protected topological phase), the entanglement spectrum (ES) resembles the energy spectrum on virtual edge, that is the Li-Haldane conjecture. In this way, the ES plays an important probe to detect the topological phases according to this bulk-edge correspondence. When a system is fully gapped, both in bulk and edge, the ES still remains similar to the virtual edge spectrum which can be explained by the recently proposed wormhole effect in the path integral of reduced density matrix. However, what will happen in the ES when the system is fully gapless? We find that though the ES roughly seems like an edge energy spectrum, and it actually contains relevant long-range interaction which modifies the intrinsic physics of entanglement Hamiltonian (EH). Moreover, the mechanism of short-/long-range interaction in EH can be understood as the confinement/deconfinement of worldlines in a path integral of reduced density matrix. Our work demonstrates that the gapless mode can induce a long-range interaction in EH.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 6 figures
Electron-magnon coupling at the interface of a “twin-twisted” antiferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Yue Sun, Fanhao Meng, Sijia Ke, Kun Xu, Hongrui Zhang, Aljoscha Soll, Zdeněk Sofer, Arun Majumdar, Ramamoorthy Ramesh, Jeffrey B. Neaton, Jie Yao, Joseph Orenstein
We identify a “twin-twist” angle in orthorhombic two-dimensional magnets that maximizes interlayer orbital overlap and enables strong interfacial coupling. Focusing on the van der Waals antiferromagnet CrSBr, we show that this twist angle, near 72 deg, aligns diagonal lattice vectors across the layers, enhancing the interlayer hopping that is spin-forbidden in pristine systems and orbital-forbidden in 90-deg-twisted samples. The enhanced hopping modifies the electronic structure and activates a novel mechanism for excitation of interfacial magnons. Using optical probes we discover that excitons on one side of the interface selectively excite magnons localized on the opposite side. We show that this cross-coupling phenomenon can be understood as a consequence of the spin-transfer torque as that arises as electrons tunnel across the twin-twisted interface. Our findings demonstrate that large-angle twisting in anisotropic 2D materials offers a powerful tool for engineering spin and charge transport through controlled interlayer hybridization, opening new avenues for twisted magnetism and strongly correlated moiré physics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21+10 pages, 6+8 figures
Study of the uniform electron gas through parametrized partition functions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Tommaso Morresi, Giovanni Garberoglio, Hongwei Xiong, Yunuo Xiong
We investigate the energy per particle, static structure factor, and momentum distribution of the uniform electron gas for different conditions defined by the dimensionless temperature $ \Theta = 0.25 - 1.0$ and average interparticle distance $ r_s = 0.5 - 80.0$ using path-integral Monte Carlo (PIMC) simulations. For small $ r_\text{s}$ ($ r_\text{s}\leq10$ ) where the sign problem is particularly challenging, we employ a recent approach based on an analytic continuation of the partition function using a real parameter $ \xi$ , which allows a generalization from bosons ($ \xi=1$ ) to fermions ($ \xi=-1$ ). We show that the results are in good agreement with other state-of-the-art methods while requiring low computational resources. For large $ r_\text{s}$ ($ r_\text{s}=80$ ), we use direct PIMC exploiting the good behaviour of the thermodynamic properties for negative $ \xi$ . In this framework we demonstrate that, for large $ r_s$ , the small negative region of $ \xi$ can be utilized to extract information about the true fermionic limit, where $ \xi = -1$ .
Materials Science (cond-mat.mtrl-sci)
Mechanisms for the ultralow room-temperature resistivity of SrMoO$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Jennifer Coulter, Fabian B. Kugler, Harrison LaBollita, Antoine Georges, Cyrus E. Dreyer
Materials with exceptionally low resistivities at room temperature are currently heavily sought after for next-generation interconnects. SrMoO$ _3$ has one of the lowest experimentally-reported room-temperature resistivities, yet the origin of this property has remained a mystery. Using the Boltzmann transport equation we determine that electron-phonon scattering limits transport at room temperature and is responsible for the approximate $ T^2$ behavior of the resistivity at intermediate temperatures, often attributed to electron-electron Fermi-liquid scattering. We show that the weak electron-phonon coupling, which is similar to, e.g., copper, combined with high electron group velocities for states near the Fermi level, explains the low resistivity of SrMoO$ _3$ . Additionally, the strength of the electron-phonon coupling is found to be sensitive to structural distortions, which may explain disagreements in the literature between single crystal and thin film measurements. The electron-phonon scattering in SrMoO$ _3$ is insensitive to static Coulomb interactions in the partially-filled transition-metal $ d$ orbitals, in contrast to similar oxides such as SrVO$ _3$ . These findings have significant implications for theoretical interpretation of direct-current resistivity in transition-metal oxides and beyond.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Coercive Field Reduction in Ultra-thin Al1-XScXN via Interfacial Engineering with a Scandium Electrode
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Yinuo Zhang, Rajeev Kumar Rai, Giovanni Esteves, Yubo Wang, Deep M. Jariwala, Eric A. Stach, Roy H. Olsson III
Aluminum scandium nitride (AlScN) ferroelectrics are promising for next-generation non-volatile memory applications due to their high remnant polarization as well as fast switching and scalability to nanometer thicknesses. As device dimensions shrink, the coercive field in ultra-thin ferroelectric films increases, which challenges low-voltage operation. We demonstrate that interfacial engineering through bottom electrode selection and strain management reduces this coercive field increase and improves ferroelectric performance. Robust ferroelectricity is observed in ultra-thin AlScN capacitors deposited on a Sc bottom electrode under both alternating current and direct current conditions. The coercive field is reduced by over 20 percent compared to capacitors with an Al bottom electrode. Furthermore, dynamic switching behavior is analyzed using the KAI model. At low frequencies (less than 16.7 kHz), capacitors with Sc and Al bottom electrodes exhibit comparable KAI exponents (0.036 and 0.028, respectively), indicating similar switching kinetics. However, at higher frequencies, the capacitor with an Al bottom electrode shows a significantly higher exponent (0.093), indicating stronger frequency dependence, whereas the capacitor with a Sc bottom electrode maintains a stable exponent of 0.036. Scanning Electron Nanobeam Diffraction is used to measure strain differences in AlScN thin films grown on templates with different lattice mismatch, revealing a correlation between lattice mismatch, film strain, and switching behavior in ultra-thin films.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
27 pages with four figures of manuscript with 10 pages of supporting information. This work has been submitted to ACS Nano
Entangled Interlocked Diamond-like (Diamondiynes) Lattices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
C. M. O. Bastos, E. J. A. dos Santos, R. A. F. Alves, Alexandre C. Dias, L. A. Ribeiro Junior, D. S. Galvão
Diamondynes, a new class of diamond-like carbon allotropes composed of carbon with sp$ ^2$ /sp$ ^3$ -hybridized carbon networks, exhibit unique structural motifs that have not been previously reported in carbon materials. These architectures feature sublattices that are both interlocked and capable of relative movement. Using ab initio simulations, we have conducted an extensive investigation into the structural and electronic properties of five diamondyne structures. Our results show that diamondiynes are thermodynamically stable and exhibit wide electronic band gaps, from 2.2 eV to 4.0 eV. They are flexible yet highly resistant compared to other diamond-like structures. They have relatively small cohesive energy values, consistent with the fact that one diamondyne structure (2f-unsym) has already been experimentally realized. Our results provide new physical insights into diamond-like carbon networks and suggest promising directions for the development of porous, tunable frameworks with potential applications in energy storage and conversion.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages
Kardar–Parisi–Zhang universality in optically induced lattices of exciton–polariton condensates
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
D. Novokreschenov, V. Neplokh, M. Misko, N. Starkova, T. Cookson, A. Kudlis, A. Nalitov, I. A. Shelykh, A. V. Kavokin, P. Lagoudakis
We investigate space-time coherence in one-dimensional lattices of exciton-polariton condensates formed by fully reconfigurable non-resonant optical pumping. Starting from an open-dissipative Gross-Pitaevskii equation with deterministic reservoir kinetics and stochastic condensate noise, we derive a discrete complex-field model that incorporates coherent tunnelling, reservoir-mediated dissipative coupling and gain-saturation non-linearity. Adiabatic elimination of fast density fluctuations reveals a wedge-shaped region in the complex hopping plane where the coarse-grained phase dynamics reduces to the Kardar-Parisi-Zhang (KPZ) equation. By computing high-resolution phase diagrams of the temporal and spatial scaling exponents we pinpoint the boundaries separating the KPZ domain from the Edwards-Wilkinson (EW) regime. Large-scale graphics processing unit (GPU) simulations of chains containing up to $ N=2000$ condensates confirm these predictions: inside the wedge the exponents converge to $ \beta_{N}=\textbf{0.329}(3)!\approx!1/3$ and $ \chi_{N}=\textbf{0.504}(4)!\approx!1/2$ , whereas outside it the dynamics moves away from KPZ and ultimately flows toward the EW fixed point, although finite system size and finite observation time may yield intermediate effective exponents. These results pave the way to the implementation of ultrafast KPZ-simulators based on one-dimensional arrays of exciton-polariton condensates.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Exploring Topological and Localization Phenomena in SSH Chains under Generalized AAH Modulation: A Computational Approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
The Su-Schrieffer-Heeger (SSH) model serves as a canonical example of a one-dimensional topological insulator, yet its behavior under more complex, realistic conditions remains a fertile ground for research. This paper presents a comprehensive computational investigation into generalized SSH models, exploring the interplay between topology, quasi-periodic disorder, non-Hermiticity, and time-dependent driving. Using exact diagonalization and specialized numerical solvers, we map the system’s phase space through its spectral properties and localization characteristics, quantified by the Inverse Participation Ratio (IPR). We demonstrate that while the standard SSH model exhibits topologically protected edge states, these are destroyed by a localization transition induced by strong Aubry-André-Harper (AAH) modulation. Further, we employ unsupervised machine learning (PCA) to autonomously classify the system’s phases, revealing that strong localization can obscure underlying topological signatures. Extending the model beyond Hermiticity, we uncover the non-Hermitian skin effect, a dramatic localization of all bulk states at a boundary. Finally, we apply a periodic Floquet drive to a topologically trivial chain, successfully engineering a Floquet topological insulator characterized by the emergence of anomalous edge states at the boundaries of the quasi-energy zone. These findings collectively provide a multi-faceted view of the rich phenomena hosted in generalized 1D topological systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Machine Learning (cs.LG)
Theory of bound magnetic polarons in cubic and uniaxial antiferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Dawid Bugajewski, Carmine Autieri, Tomasz Dietl
Motivated by a recent debate about the origin of remanent magnetization and the corresponding anomalous Hall effect in antiferromagnets and their subclass, altermagnets, a theory of bound magnetic polarons (BMPs) in anisotropic antiferromagnetic semiconductors is developed. The theory describes quantitatively the experimentally observed magnitude of excess magnetization and its dependence on the magnetic field in cubic antiferromagnetic EuTe. In contrast to the cubic case, our theory predicts the presence of magnetization hysteresis below Néel temperature in antiferromagnets with uniaxial anisotropy. We show, employing material parameters implied by experimental and ab initio results, that the magnitudes of remanent magnetization and the coercive field are in accord with recent experimental observations for altermagnetic hexagonal MnTe. While the altermagnets have an intrinsic contribution to the remanent magnetization and the anomalous Hall effect, our theory explains the origin of an extrinsic contribution. Our findings address, therefore, a question about the relative contribution to the remanent magnetization of bound magnetic polarons and weak ferromagnetism driven by the antisymmetric exchange interaction, the latter weakened by the formation of antiferromagnetic domains. Furthermore, we provide the theory of BMP spontaneous spin splitting, which can be probed optically.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
7 pages, 3 figures
Spontaneous emission and Purcell effect: some aspects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
P. P. Abrantes, D. Szilard, C. Farina
This chapter, part of the Proceedings of the III International Workshop on Quantum Nonstationary Systems (eds. Alexandre Dodonov and Lucas Chibebe Celeri), held in Brasilia in August 2024, offers a comprehensive overview of spontaneous emission (SE) and the Purcell effect within the broader context of quantum electrodynamics (QED) and vacuum fluctuations. It begins with a historical and theoretical review, tracing the development of classical and quantum electromagnetic theories. The chapter then examines how the SE rate of a quantum emitter is fundamentally influenced by its electromagnetic environment, the so-called Purcell effect, through canonical examples, such as emitters near perfectly conducting plates and inside cavities, as well as more advanced scenarios. Special attention is given to modern strategies for tailoring SE using engineered environments, including plasmonic cloaks, composite media near percolation thresholds, metal-insulator phase transitions, and strain-induced modulation in phosphorene. Analytical techniques, such as mode summation and Green’s function formalism, are employed to describe how surrounding materials and boundary conditions affect local field modes and the local density of states. The findings underscore both the theoretical depth and experimental relevance of SE modulation, paving the way for innovations in nano-optics, quantum technologies, and advanced material design.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
28 pages, 11 figures. Chapter of the Proceedings for the III International Workshop on Quantum Nonstationary Systems (eds. Alexandre Dodonov and Lucas Chibebe Céleri)
Chapter in A. Dodonov and L. C. Celeri (Eds.), Proceedings of QNS III International Workshop on Quantum Nonstationary Systems (LF Editorial, Sao Paulo, 2025)
Going beyond density functional theory accuracy: Leveraging experimental data to refine pre-trained machine learning interatomic potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Shriya Gumber, Lorena Alzate-Vargas, Benjamin T. Nebgen, Arjen van Veelen, Smit Kadvani, Tammie Gibson, Richard Messerly
Machine learning interatomic potentials (MLIPs) are inherently limited by the accuracy of the training data, usually consisting of energies and forces obtained from quantum mechanical calculations, such as density functional theory (DFT). Since DFT itself is based on several approximations, MLIPs may inherit systematic errors that lead to discrepancies with experimental data. In this paper, we use a trajectory re-weighting technique to refine DFT pre-trained MLIPs to match the target experimental Extended X-ray Absorption Fine Structure (EXAFS) spectra. EXAFS spectra are sensitive to the local structural environment around an absorbing atom. Thus, refining an MLIP to improve agreement with experimental EXAFS spectra also improves the MLIP prediction of other structural properties that are not directly involved in the refinement process. We combine this re-weighting technique with transfer learning and a minimal number of training epochs to avoid overfitting to the limited experimental data. The refinement approach demonstrates significant improvement for two MLIPs reported in previous work, one for an established nuclear fuel: uranium dioxide (UO$ _2$ ) and second one for a nuclear fuel candidate: uranium mononitride (UN). We validate the effectiveness of our approach by comparing the results obtained from the original (unrefined) DFT-based MLIP and the EXAFS-refined MLIP across various properties, such as lattice parameters, bulk modulus, heat capacity, point defect energies, elastic constants, phonon dispersion spectra, and diffusion coefficients. An accurate MLIP for nuclear fuels is extremely beneficial as it enables reliable atomistic simulation, which greatly reduces the need for large number of expensive and inherently dangerous experimental nuclear integral tests, traditionally required for the qualification of efficient and resilient fuel candidates.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Statistical mechanics of fluids with hidden degrees of freedom
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-13 20:00 EDT
Masanari Shimada, Tetsuya J. Kobayashi
Although coarse-grained models have been widely used to explain exotic phenomena in complex fluids, such as droplet formation in living cells, these conventional approaches often fail to capture the intricate microscopic degrees of freedom that such fluids inherently possess. In this study, we propose a model that incorporates distinct microscopic degrees of freedom and their interactions, without directly relying on conventional coarse-grained descriptions. By introducing two key assumptions, we show that the system can exhibit equilibrium states characterized by heterogeneous density profiles with finite length scales, resembling those typically associated with non-equilibrium phenomena. These findings highlight the importance of distinguishing between equilibrium states and non-equilibrium steady states in highly complex systems.
Soft Condensed Matter (cond-mat.soft)
16 pages, 4 figures
Neel order, spin-spiral, and spin liquid ground state in frustrated three dimensional system CaMn2P2: A DFT+U and spin dynamics study
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Bidyut Mallick, Sk. Soyeb Ali, S. K. Panda
We investigate the magnetic ground state and phase transitions in the frustrated three-dimensional system CaMn2P2 using first-principles calculations combined with spin-dynamics simulations. Our DFT+U calculations reveal that CaMn2P2 exhibits an indirect gap semiconducting ground state with a localized Mn2+ electronic configuration and negligible spin-orbit coupling effects. The computed exchange interactions show that the magnetic behavior is well described by a isotropic Heisenberg Hamiltonian. In this model, there are two major couplings: the NN interaction J1 couples the two Mn layers along the c-axis and next NN J2 is in the a-b plane where Mn ions form a hexagonal layer structure. Our results show that both J1 and J2 are antiferromagnetic in nature and as a consequence J2 induce frustration owing to the in-plane triangular geometry of the Mn-ions. The J1 is found to promote long-range antiferromagnetic order, while the J2 is responsible for spin canting and disorder. Our spin-wave analysis confirms that the system stabilizes a spin-spiral ground state with a propagation vector q = (1/6 , 1/6, 0) in agreement with neutron diffraction experiments. By tuning the J2/J1 ratio, we construct a phase diagram that reveals a transition from a collinear Neel antiferromagnetic state to different spin-spiral phases, and eventually to a disordered phase at large frustration. Atomistic spin-dynamics simulations capture the temperature evolution of the magnetism and reproduce the experimentally measured magnetic data with good accuracy. Furthermore, for large J2/J1, we identify a low temperature phase with slow spin relaxation and persistent fluctuations, suggesting a spin-liquid like state. Our study provides an understanding of frustration induced magnetism in CaMn2P2 and establishes it as a realization of J1-J2 model in three-dimensional lattice for exploring emergent magnetic phases.
Strongly Correlated Electrons (cond-mat.str-el)
Accepted in Phys. Rev. B
Low and Anisotropic Thermal Conductivity in Mixed-Valent Sn$_2$S$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Xingang Jiang, Yongheng Li, Weiping Guo, Qi Ren, Gang Tang, Zhong-Zhen Luo, Jiawang Hong
Compounds of Sn, such as SnSe and SnS, exhibit novel phonon characteristics and low thermal conductivity, making them emerging star materials in the thermoelectric family. In this work, through the Boltzmann transport equation scheme and the Wigner thermal transport model, quasi-1D mixed-valent Sn$ _2$ S$ _3$ were found to exhibit a low thermal conductivity along c-axis with a weak temperature dependence. The low thermal conductivity is attributed to the anharmonic rattling vibrations of weakly bonded Sn(II) atoms, which are influenced by the coulomb interaction of lone pairs at adjacent Sn(II) atoms. The rattling of Sn(II) induces low-frequency flat optical phonons and avoids crossing behavior. The atomic displacements and mean square displacement (MSD) analysis reveal that Sn(II) atoms exhibit significantly greater and anisotropic displacements compared to Sn(IV) and S, confirming that Sn(II) behaves as a rattler. The results obtained from this work suggest an opportunity to discover low thermal conductivity in mixed-valent compounds.
Materials Science (cond-mat.mtrl-sci)
Topotactic oxidation of Ruddlesden-Popper nickelates reveals new structural family: oxygen-intercalated layered perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Dan Ferenc Segedin, Jinkwon Kim, Harrison LaBollita, Nicole K. Taylor, Kyeong-Yoon Baek, Suk Hyun Sung, Ari B. Turkiewicz, Grace A. Pan, Abigail Y. Jiang, Maria Bambrick-Santoyo, Tobias Schwaigert, Casey K. Kim, Anirudh Tenneti, Alexander J. Grutter, Shin Muramoto, Alpha T. N’Diaye, Ismail El Baggari, Donald A. Walko, Hua Zhou, Charles M. Brooks, Antia S. Botana, Darrell G. Schlom, Julia A. Mundy
Layered perovskites such as the Dion-Jacobson, Ruddlesden-Popper, and Aurivillius families host a wide range of correlated electron phenomena, from high-temperature superconductivity to multiferroicity. Here we report a new family of layered perovskites, realized through topotactic oxygen intercalation of La_{n+1}Ni_{n}O_{3n+1} (n=1-4) Ruddlesden-Popper nickelate thin films grown by ozone-assisted molecular-beam epitaxy. Post-growth ozone annealing induces a large c-axis expansion - 17.8% for La_{2}NiO_{4} (n=1) - that monotonically decreases with increasing n. Surface X-ray diffraction coupled with Coherent Bragg Rod Analysis reveals that this structural expansion arises from the intercalation of approximately 0.7 oxygen atoms per formula unit into interstitial sites within the rock salt spacer layers. The resulting structures exhibit a spacer layer composition intermediate between that of the Ruddlesden-Popper and Aurivillius phases, defining a new class of layered perovskites. Oxygen-intercalated nickelates exhibit metallicity and significantly enhanced nickel-oxygen hybridization, a feature linked to high-temperature superconductivity. Our work establishes topotactic oxidation as a powerful synthetic approach to accessing highly oxidized, metastable phases across a broad range of layered oxide systems, offering new platforms to tune properties via spacer-layer chemistry.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Slip electron flow in GaAs microscale constrictions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Daniil I. Sarypov, Dmitriy A. Pokhabov, Arthur G. Pogosov, Evgeny Yu. Zhdanov, Andrey A. Shevyrin, Alexander A. Shklyaev, Askhat K. Bakarov
Hydrodynamic electron transport in solids, governed by momentum-conserving electron-electron collisions, offers a unique framework to explore collective phenomena. Within this framework, correlated electron motion is modeled as viscous fluid flow, with viscosity serving as the interaction parameter. Advances in electron hydrodynamics remain constrained by two unresolved issues: the questionable existence of perfect boundary slip$ \unicode{x2013}$ a hallmark of frictionless transport$ \unicode{x2013}$ in electron fluids, and the lack of quantitative experimental confirmation of the theoretical relation linking the viscosity to electron-electron scattering length. Here, we resolve this through independent measurements of these quantities in the same electron system in GaAs/AlGaAs heterostructure. Our experiments provide direct evidence of perfect boundary slip in microscale constrictions$ \unicode{x2013}$ unprecedented phenomenon for electron liquid that parallels ultrafast water transport in carbon nanotubes. These findings bridge the fields of electron hydrodynamics and nanofluidics, highlighting the transformative potential of hydrodynamic engineering across condensed matter and fluidic technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 8 figures
GEARS H: Accurate machine-learned Hamiltonians for next-generation device-scale modeling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Anubhab Haldar, Ali K. Hamze, Nikhil Sivadas, Yongwoo Shin
We introduce GEARS H, a state-of-the-art machine-learning Hamiltonian framework for large-scale electronic structure simulations. Using GEARS H, we present a statistical analysis of the hole concentration induced in defective $ \mathrm{WSe}_2$ interfaced with Ni-doped amorphous $ \mathrm{HfO}_2$ as a function of the Ni doping rate, system density, and Se vacancy rate in 72 systems ranging from 3326 to 4160 atoms-a quantity and scale of interface electronic structure calculation beyond the reach of conventional density functional theory codes and other machine-learning-based methods. We further demonstrate the versatility of our architecture by training models for a molecular system, 2D materials with and without defects, solid solution crystals, and bulk amorphous systems with covalent and ionic bonds. The mean absolute error of the inferred Hamiltonian matrix elements from the validation set is below 2.4 meV for all of these models. GEARS H outperforms other proposed machine-learning Hamiltonian frameworks, and our results indicate that machine-learning Hamiltonian methods, starting with GEARS H, are now production-ready techniques for DFT-accuracy device-scale simulation.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
13 pages, 3 figures, later version will add supplement
Nonlinear Néel Spin-Orbit Torque in Centrosymmetric Antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Jin Cao, Weikang Wu, Huiying Liu, Shen Lai, Cong Xiao, X. C. Xie, Shengyuan A. Yang
Electric control of Néel vector is a central task of antiferromagnetic (AFM) spintronics. The major scheme so far relies on the linear Néel torque, which however is restricted to AFMs with broken inversion symmetry. Here, we propose a nonlinear Néel spin-orbit torque, uniquely enabling electric control in the vast class of centrosymmetric AFMs, where the existing scheme fails. Importantly, its intrinsic component, rooted in sublattice-resolved band quantum geometry, offers two additional advantages: It operates also in $ \mathcal{PT}$ -symmetric AFM insulators, where linear torque is forbidden; and it has anti-damping character, making it more efficient in driving magnetic dynamics. Combined with first-principles calculations, we predict large effect in MnRh and MnBi$ _{2}$ Te$ _{4}$ , which can be readily detected in experiment. Our work unveils a new fundamental effect, offers a new strategy of electric control in AFM systems beyond the existing paradigm, and opens the door to the field of nonlinear AFM spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures and 1 table
Field-free perpendicular magnetization switching by altermagnet with collinear spin current
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
M. Q. Dong, Zhi-Xin Guo, Xin-Gao Gong
The generation of collinear spin current (CSC), where both the propagation direction and spin-polarized direction aligned perpendicularly to the applied charge current, is crucial for efficiently manipulating systems with perpendicular magnetic anisotropy used in high-density magnetic recording. However, the efficient generation of CSC remains a challenge. In this work, based on the symmetry analysis, we propose that CSC can be effectively generated using altermagnets when the charge current is aligned along specific directions, due to spin-dependent symmetry breaking. This proposal is supported by density functional theory (DFT) and Boltzmann transport equation (BTE) calculations on a series of altermagnetic materials, including RuO2, Mn5Si3, KRu4O8 and CuF2, where unusually large CSC is produced by the charge current along certain orientations. Furthermore, we introduce a physical quantity, the spin-splitting angle, to quantify the efficiency of CSC generated by the charge current. We find that the spin-splitting angle ranges from 0.24 to 0.57 in these altermagnets, which is significantly larger than the spin-Hall angle typically observed in the anomalous spin-Hall effect, where the spin-Hall angle is generally less than 0.1. Our findings provide an effective method for manipulating spin currents, which is advantageous for the exploration of altermagnetic spintronic devices with field-free perpendicular magnetization switching.
Materials Science (cond-mat.mtrl-sci)
Symmetry Rules on Multipole Interactions under Crystallographic Point Groups and Application to Multiple-$Q$ Multipole States
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Multipole degrees of freedom describe the mutual interplay among the charge, spin, and orbital degrees of freedom in electrons, which provides a microscopic understanding of unconventional electronic orderings and their associated physical phenomena. We here show the symmetry rules on multipole interactions under crystallographic point groups in a systematic manner. Depending on the bond symmetries, we show the necessary symmetry conditions of the antisymmetric multipole interactions, which correspond to the extension of the Dzyaloshinskii-Moriya interaction, as well as the symmetric ones, which correspond to the extension of the compasslike interaction. Furthermore, we demonstrate that the symmetry-allowed multipole interactions can become a source of exotic multiple-$ Q$ multipole orderings. As a specific example, we analyze the effective model with the antisymmetric quadrupole interaction on a triangular lattice and show the emergence of the triple-$ Q$ quadrupole state. Our results indicate that multipole interactions that often arise from the heavy-fermion, frustrated, and nematic systems can potentially induce further unconventional quantum states of matter.
Strongly Correlated Electrons (cond-mat.str-el)
23 pages, 2 figures, 27 tables
J. Phys. Soc. Jpn. 94, 074704 (2025)
Poor Man’s Majoranon in Two Quantum Dots Dressed by Superconducting Quasi-Excitations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Zhi-Lei Zhang, Guo-Jian Qiao, C. P. Sun
In a hybrid system consisting of two quantum dots (QDs) coupled to a superconductor (SC), zero-bias peaks in the differential conductance spectrum have been reported as potential signatures of Majorana fermions (MFs). However, such signatures typically appear only at specific parameter values of the QDs–so-called `sweet spots’–and are referred to as the Poor Man’s Majorana (PMM). To investigate whether these signatures can be conclusively attributed to genuine MFs emerging over a continuous parameter range, we present an alternative approach that microscopically incorporates the superconducting effects into the QDs, rather than simply attribute them into two phenomenological parameters of QDs. This forms the dressed Majorana fermions (DMFs), which can be viewed as superpositions of quasi-excitations from both the QDs and the SC. We show that DMFs can localize at one end of a one-dimensional SC and persist across a continuous parameter range, thereby enhancing the feasibility of experimental detection. Our results provide a more accurate description of the PMM in such hybrid systems and offer practical guidance for observing end-localized PMM modes in continuous one-dimensional SC.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Roadmap for electronic structure, anharmonicity, and electron-phonon calculations in locally disordered inorganic and hybrid halide perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Marios Zacharias, George Volonakis, Laurent Pedesseau, Claudine Katan, Feliciano Giustino, Jacky Even
The role of data in modern materials science becomes more valuable and accurate when effects such as electron-phonon coupling and anharmonicity are included, providing a more realistic representation of finite-temperature material behavior. Furthermore, positional polymorphism, characterized by correlated local atomic disorder usually not reported by standard diffraction techniques, is a critical yet underexplored factor in understanding the electronic structure and transport properties of energy-efficient materials, like halide perovskites. In this manuscript, we present a first-principles methodology for locally disordered (polymorphous) cubic inorganic and hybrid halide perovskites, rooted in the special displacement method, that offers a systematic and alternative approach to molecular dynamics for exploring finite-temperature properties. By enabling a unified and efficient treatment of anharmonic lattice dynamics, electron-phonon coupling, and positional polymorphism, our approach generates essential data to predict temperature-dependent phonon properties, free energies, band gaps, and effective masses. Designed with a high-throughput spirit, this framework has been applied across a range of inorganic and hybrid halide perovskites: CsPbI3, CsPbBr3, CsSnI3, CsPbCl3, MAPbI3, MAPbBr3, MASnI3, MAPbCl3, FAPbI3, FAPbBr3, FASnI3, and FAPbCl3. We provide a comprehensive comparison between theoretical and experimental results and we systematically uncover trends and insights into their electronic and thermal behavior. For all compounds, we demonstrate strong and consistent correlations between local structural disorder, band gap openings, and effective mass enhancements.
Materials Science (cond-mat.mtrl-sci)
Method of analysis of the spectra obtained by microfocused Brillouin light scattering
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Nessrine Benaziz, Thibaut Devolder, Jean-Paul Adam
Brillouin Light Scattering is a powerful technique to measure the microwave excitations present in a magnetic system. In microfocused mode, the light is focused on the sample using a microscope objective. This accelerates substantially the measurement but results in mixing the response of all microwave excitations into a single spectrum, such that modeling is required to disentangle the contribution of each spin wave. By assuming that a spectrum collected in microfocused mode can be approximated by the sum of all back-scattering spectra that can be collected by the microscope objective, we develop a simple and direct way of interpreting spectra. The model is compared to experimental data collected on a 50 nm thick CoFeB magnetic film. The model allows the understanding of the influence of the optical properties of a sample, of the dispersion relation of the spin wave eigenexcitations and of their thickness profiles, as well as of their populations onto the magnitudes and the lineshapes of the characteristic features of a spectrum
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Time reversal symmetry breaking and s-wave superconductivity in CaPd2Ge2: A $μ$SR study
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-13 20:00 EDT
V. K. Anand, A. Bhattacharyya, D. T. Adroja, K. Panda, P. K. Biswas, A. D. Hillier, B. Lake
$ {\rm CaPd_2Ge_2}$ which crystallizes in $ {\rm ThCr_2Si_2}$ -type body-centered tetragonal structure exhibits superconductivity below the critical temperature $ T_{\rm c} = 1.69$ ~K@. We have investigated the superconducting gap structure and time reversal symmetry of the ground state in $ {\rm CaPd_2Ge_2}$ by means of muon spin relaxation and rotation ($ \mu$ SR) measurements. Our analysis of $ \mu$ SR data collected in transverse magnetic field reveals BCS superconductivity with a single-band $ s$ -wave singlet pairing and an isotropic energy gap having the value $ 2\Delta(0)/k_{\rm B}T_{\rm c} = 3.50(1)$ . Further, an increased relaxation rate in zero field $ \mu$ SR asymmetry spectra below $ T_{\rm c} $ provides evidence for the presence of a spontaneous magnetic field in the superconducting state revealing that the time-reversal symmetry is broken in $ {\rm CaPd_2Ge_2}$ .
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
8 pages, 5 figures
Phys. Rev. B 108, 224519 (2023)
Studying all-optical magnetization switching of GdFe by double-pulse laser excitation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Rahil Hosseinifar, Felix Steinbach, Ivar Kumberg, José Miguel Lendínez, Sangeeta Thakur, Sebastien E. Hadjadj, Jendrik Gördes, Chowdhury S. Awsaf, Mario Fix, Manfred Albrecht, Florian Kronast, Unai Atxitia, Clemens von Korff Schmising, Wolfgang Kuch
The tremendous interest in the technology and underlying physics of all-optical switching of magnetization brings up the question of how fast the switching can occur and how high the frequency of writing the data with ultrafast laser pulses can be. To answer this question, we excited a GdFe ferrimagnetic alloy, the magnetization of which can be reversed by single laser pulses, a phenomenon known as toggle switching, by two pulses with a certain time delay in between. Using photoemission electron microscopy and Kerr microscopy for magnetic domain imaging, we explore the effects of varying fluences of the first and second pulse as well as the time delay between the two pulses. Our results show that when the fluence of the first pulse is adjusted just above the threshold of single-pulse switching, a second pulse with about 60% of the fluence of the first pulse, arriving only 3 ps later, switches the magnetization back. This reswitching persists up to about 40 ps pulse separation. We interpret the latter as the time required for the sample to cool down and remagnetize after the first pulse. For shorter time delays below about 2 ps, no re-switching occurs. However, the effect of the two pulses adds up, enabling switching for fluences of both pulses below the threshold for single-pulse switching. Atomistic spin dynamics simulations are used to model the experimental data, successfully confirming our results.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Disentangling Electronic and Ionic Nonlinear Polarization Effects in the THz Kerr Response of LaAlO$_{3}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Chao Shen, Maximilian Frenzel, Sebastian F. Maehrlein, Zhanybek Alpichshev
Nonlinear responses to intense terahertz (THz) fields provide unique insights into complex dynamics of contemporary material systems. However, the interpretation of the obtained data, in particular, distinguishing genuine ionic oscillations from the instantaneous electronic responses in THz Kerr effect remains challenging. Here, we combine two-dimensional Terahertz Kerr effect (2D-TKE) spectroscopy experiments and their modeling to unravel complex THz-induced temporal oscillations in twinned LaAlO$ _3$ crystals at low temperatures. We identify the 1.1 THz mode as $ E_g$ Raman phonon, while 0.86 THz and 0.36 THz signals are due to spurious effects resulting from the co- and counter-propagation of THz and optical probe pulses in birefringent twin domains. Furthermore, we determine that the $ E_g$ mode is excited via a two-photon process, whereas THz pulse reflections at the sample surface produce a temporal response that can mimic anharmonic phonon coupling. Our findings highlight the importance of propagation effects in nonlinear THz experiments and provide a refined framework for interpreting THz polarization dynamics in birefringent crystals.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Optics (physics.optics)
Break-up of an active chiral fluid
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-13 20:00 EDT
Luke Neville, Jens Eggers, Tanniemola B. Liverpool
We consider the non-linear dynamics governing the break-up of a two-dimensional strip of active chiral fluid. We observe that the strip thickness goes to zero at the pinch off points as a power law in finite time. Using slender body theory combined with a scaling analysis, we identify a new class of scaling exponents and scaling functions characterizing the speed and shape of break-up in these systems. The scaling analysis is in excellent agreement with direct numerical simulations of the hydrodynamic equations
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
5 pages main, 3 pages supplemental, 3 figures
Optical absorption in hexagonal-diamond Si and Ge nanowires: insights from STEM-EELS experiments and ab initio theory
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Luiz H. G. Tizei, Michele Re Fiorentin, Thomas Dursap, Theodorus M. van den Berg, Marc Túnica, Maurizia Palummo, Mathieu Kociak, Laetitia Vincent, Michele Amato
Hexagonal-diamond (2H) group IV nanowires are key for advancing group IV-based lasers, quantum electronics, and photonics. Understanding their dielectric response is crucial for performance optimization, but their optical absorption properties remain unexplored. We present the first comprehensive study of optical absorption in 2H-Si and 2H-Ge nanowires, combining high-resolution STEM, monochromated EELS, and ab initio simulations. The nanowires, grown in situ in a TEM as nanobranches on GaAs stems, show excellent structural quality: single crystalline, strain-free, minimal defects, no substrate contamination, enabling access to intrinsic dielectric response. 2H-Si exhibits enhanced absorption in the visible range compared to cubic Si, with a marked onset above 2.5 eV. 2H-Ge shows absorption near 1 eV but no clear features at the direct bandgap, as predicted by ab initio simulations. A peak around 2 eV in aloof-beam spectra is attributed to a thin 3C-Ge shell. These findings clarify structure-optical response relationships in 2H materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nano Letters 25 (2025) 8604
On the role of non-linear latent features in bipartite generative neural networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-13 20:00 EDT
Tony Bonnaire, Giovanni Catania, Aurélien Decelle, Beatriz Seoane
We investigate the phase diagram and memory retrieval capabilities of bipartite energy-based neural networks, namely Restricted Boltzmann Machines (RBMs), as a function of the prior distribution imposed on their hidden units - including binary, multi-state, and ReLU-like activations. Drawing connections to the Hopfield model and employing analytical tools from statistical physics of disordered systems, we explore how the architectural choices and activation functions shape the thermodynamic properties of these models. Our analysis reveals that standard RBMs with binary hidden nodes and extensive connectivity suffer from reduced critical capacity, limiting their effectiveness as associative memories. To address this, we examine several modifications, such as introducing local biases and adopting richer hidden unit priors. These adjustments restore ordered retrieval phases and markedly improve recall performance, even at finite temperatures. Our theoretical findings, supported by finite-size Monte Carlo simulations, highlight the importance of hidden unit design in enhancing the expressive power of RBMs.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Machine Learning (cs.LG)
23 pages, 5 figures
On the origin of the E1 electron trap level in GaN and dilute AlxGa1-xN films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Piotr Kruszewski, Jose Coutinho, Vladimir P. Markevich, Pawel Prystawko, Lijie Sun, Jerzy Plesiewicz, Chris A. Dawe, Matthew P. Halsall, Anthony R. Peaker
The results of high-resolution Laplace deep-level transient spectroscopy (L-DLTS) measurements applied to the E1 and FeGa electron traps in dilute AlxGa1-xN films (x = 0.063), grown by metal-organic vapor phase epitaxy (MOVPE) on Ammono-GaN substrates, are presented. It is shown that the electron emission signals associated with the E1 donor and the FeGa acceptor levels split into individual components due to the aluminium fluctuations in the nearest neighbour shells around the E1 and FeGa defects. The splitting patterns observed in the L-DLTS spectra are nearly identical for both signals. Furthermore, the ratios of peak magnitudes determined from the L-DLTS analysis for both the E1 and E3 traps are consistent with calculated probabilities of finding a given number of aluminium atoms in the second nearest neighbour shell around a Ga lattice site in AlxGa1-xN with x = 0.063. These findings provide strong evidence that both the E1 and the FeGa trap states in dilute AlxGa1-xN are related to defects located in the Ga sublattice. To elucidate the origin of the E1 trap in AlxGa1-xN, we have performed a comprehensive scan of possible impurities and defects in GaN and AlxGa1-xN using hybrid density functional calculations of transition levels and their associated shifts upon substitution of Ga neighbour atoms by Al. From analysis of the results, we find that the E1 electron trap in GaN and AlxGa1-xN is most likely related to a donor transition from a carbon or molybdenum impurity atom at the gallium site, respectively.
Materials Science (cond-mat.mtrl-sci)
Actually the manuscript is under review in Applied Physics Letters
Equations of state and stability condition of mixed p-spin glass model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-13 20:00 EDT
The Sherrington-Kirkpatrick (SK) is a foundational model for understanding spin glass systems. It is based on the pairwise interaction between each two spins in a fully connected lattice with quenched disordered interactions. The nature of long-range interaction among spins in the (SK) model simplifies the study of this system by eliminating fluctuations. An advanced (SK) model, known as the p-spin model, introduces higher-order interactions that involve the interaction of P spins. This research focuses on the general Hamiltonian of the spin glass model with long-range interaction, referred to as the mixed p-spin glass model, which consists of adding all p-spin interaction terms. This research aims to derive the equation of states for this Hamiltonian, formulate the equation of state within the framework of the first replica symmetry breaking, and determine both the stability condition of the replica symmetric solution and the stability of the replicas belonging to the same group in the first step of replica symmetry breaking.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Light-induced Floquet spin-triplet Cooper pairs in unconventional magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Pei-Hao Fu, Sayan Mondal, Jun-Feng Liu, Jorge Cayao
The recently predicted unconventional magnets offer a new ground for exploring the formation of nontrivial spin states due to their inherent nonrelativistic momentum-dependent spin splitting. In this work, we consider unconventional magnets with $ d$ - and $ p$ -wave parities and investigate the effect of time-periodic light drives for inducing the formation of spin-triplet phases in the normal and superconducting states. In particular, we consider unconventional magnets without and with conventional superconductivity under linearly and circularly polarized light drives and treat the time-dependent problem within Floquet formalism, which naturally unveils photon processes and Floquet bands determining the emergent phenomena Using Floquet formalism, we reveal multiple spin-degenerate nodes in the Floquet spin density, which can be dissected into single- and double-photon processes, and connected to spin-triplet Cooper pairs. Notably, both odd- and even-frequency spin-triplet pairs can be generated by the interplay between the driving field and the unconventional magnetism. Moreover, the intrinsic spatial asymmetry of the unconventional magnet allows linearly polarized light to control magnetic and polarization directions. By tuning the driving amplitude, frequency, and polarization, Floquet spin density and pairing amplitude can be dynamically controlled, offering promising applications in Floquet engineering spintronic and superconducting devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
36 pages, 7 figurs
1D YIG hole-based magnonic nanocrystal
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
K. O. Levchenko, K. Davídková, R. O. Serha, M. Moalic, A. A. Voronov, C. Dubs, O. Surzhenko, M. Lindner, J. Panda, Q. Wang, O. Wojewoda, B. Heinz, M. Urbánek, M. Krawczyk, A. V. Chumak
Magnetic media with artificial periodic modulation-magnonic crystals (MCs) - enable tunable spin-wave dynamics and band structure engineering. Nanoscaling enhances these capabilities, making magnonic nanocrystals promising for both fundamental studies and applications. Here, we report on the design, fabrication, and characterization of one-dimensional YIG MCs with nanoholes ($ d \approx $ 150 nm) spaced $ a \approx 1 \mu$ m apart. Micro-focused Brillouin light scattering and propagating spin-wave spectroscopy, supported by TetraX and MuMax$ ^3$ simulations, reveal spin-wave transmission over 5 $ \mu$ m in the Damon-Eshbach configuration, and the formation of pronounced band gaps with rejection levels up to 26 dB. Detailed analysis of the spin-wave dispersion uncovered complex mode interactions, including two prominent anticrossings at 3.1 and 18.7 rad/$ \mu$ m, between which the spin-wave energy is predominantly carried by the $ n$ = 2 mode, enabling efficient transmission. The results advance the development of functional MCs and open pathways toward 2D magnonic nanoarrays and magnonic RF nanodevices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Manuscript: 6 pages, 4 figures; Supplementary materials: 12 pages, 11 figures
A Taylor Series Approximation Model for Characterizing the Output Resistance of a GFET
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Xiomara Ribero-Figueroa, Anibal Pacheco-Sanchez, Tzu-Jung Huang, David Jiménez, Ivan Puchades, Reydezel Torres-Torres
The mobility-degradation-based model for the drain-to-source or output resistance of a graphene field-effect-transistor is linearized here using a Taylor series approximation. This simplification is shown to be valid from magnitudes of the gate voltage not significantly higher than the Dirac voltage, and it enables the analytical determination of the transconductance parameter, the voltage related to residual charges, and a bias-independent series resistance of the GFET. Furthermore, a continuous representation of the device’s static response is achieved when substituting the extracted parameters into the model, regardless the transfer characteristic symmetry with respect to the Dirac voltage.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
IEEE Transactions on Electron Devices, vol. 71, no. 11, pp. 7204-7207, Nov. 2024
Strongly correlated topological surface states in type-II Dirac semimetal NiTe$_{2}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Neeraj Bhatt, Asif Ali, Deepali Sharma, Sakshi Bansal, Manasi Mandal, Ravi Prakash Singh, Ravi Shankar Singh
Nontrivial topology in type-II Dirac semimetal NiTe$ _2$ leading to topologically protected surface states give rise to fascinating phenomena holding great promise for next-generation electronic and spintronic devices. Key parameters $ -$ such as lattice parameter, disorder, vacancies, and electron correlation $ -$ significantly influence the electronic structure and, subsequently, the physical properties. To resolve the discrepancy between the theoretical description and experimentally observed topological surface states, we comprehensively investigate the electronic structure of NiTe$ _2$ using angle-resolved photoemission spectroscopy and density functional theory. Although the bulk electronic structure is found to be well-described within mean field approaches, an accurate description of topological surface states is obtained only by incorporating surface electronic correlation. We reveal that the strongly correlated surface states forming Dirac-like conical crossing much below Fermi level have hybridized Ni 3$ d$ and Te 5$ p$ character. These findings underscore the intricate interplay between electron correlation and band topology, broadening our understanding of many-body correlation effects on the topological surface states in quantum materials.
Strongly Correlated Electrons (cond-mat.str-el)
to appear in Phys. Rev. B
Electric field control of third-order nonlinear Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Jiaju Yang, Lujun Wei, Yanghui Li, Lina Chen, Wei Niu, Jiarui Chen, Jun Du, Yong Pu
The third-order nonlinear Hall effect (NLHE) serves as a sensitive probe of energy band geometric property, providing a new paradigm for revealing the Berry curvature distribution and topological response of quantum materials. In the Weyl semimetal TaIrTe4, we report for the first time that the sign of the third-order NLHE reverses with decreasing temperature. Through scaling law analysis, we think that the third-order NLHE at high (T > 23 K) and low (T < 23 K) temperatures is dominated by Berry-connection polarizability (BCP) and impurity scattering, respectively. The third-order NLHE response strength can be effectively modulated by an additional applied in-plane constant electric field. At the high temperature region, the BCP reduction induced by the electric field leads to a decrease in the third-order NLHE response strength, while at the low temperature region, the electric field cause both BCP and impurity scattering effects to weaken, resulting in a more significant modulation of the third-order NLHE response strength. At 4 K and an electric field strength of 0.3 kV/cm, the modulated relative response strength could reach up to 65.3%. This work provides a new means to explore the third-order NLHE and a valuable reference for the development of novel electronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
20 pages, 5 figures
Above 20K conventional superconductivity in Cerium
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-13 20:00 EDT
Mohd Monish, Nikhlesh S Mehta, Mona Garg, Goutam Sheet (Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali)
A high superconducting critical temperature (Tc) under normal laboratory conditions in a material that is chemically simple and stable, like an elemental metal, is a hitherto unattained goal of modern science and technology. Certain elemental metals are known to display reasonably high Tc only under extraordinarily high pressures where their spectroscopic characterization and application are tightly restricted. Here we show that a Tc exceeding 20 K can be realized on pure elemental Ce under uniaxial pressure created simply by pressing a sharp metallic needle on the metal. This is a breakthrough because pure Ce does not superconduct under ambient conditions and the application of 54 GPa of hydrostatic pressure yields only a low Tc of 1.8 K in the metal. In addition, by driving the area under the needle in a mechanically controlled way to the ballistic transport regime, for the first time, we spectroscopically characterized the superconducting energy gap in a high-pressure superconducting phase and found that superconducting Ce respects the conventional Bardeen-Cooper-Shrieffer (BCS) theory.
Superconductivity (cond-mat.supr-con)
34 pages, 20 figures
Ultrafast non-volatile rewritable ferroaxial switching
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Z. Zeng, M. Först, M. Fechner, D. Prabhakaran, P. G. Radaelli, A. Cavalleri
Ultrafast switching of ferroic phases is an important research frontier, with significant technological potential. Yet, current efforts are meeting some key challenges, ranging from limited speeds in ferromagnets to intrinsic volatility of switched domains due to uncompensated depolarizing fields in ferroelectrics. Unlike these ferroic systems, ferroaxial materials host bistable states that do not break spatial-inversion or time-reversal symmetry, and are therefore immune to depolarizing fields. Yet, they are difficult to manipulate because external axial fields are not easily constructed with conventional methods. Here, we demonstrate ultrafast switching of ferroaxial order by engineering an effective axial field made up of circularly driven terahertz phonon modes. A switched ferroaxial domain remains stable for many hours and can be reversed back with a second terahertz pulse of opposite helicity. The effects demonstrated here may lead to a new platform for ultrafast information storage.
Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures of main text, plus Supplementary Material
Quantum magnetotransport in monolayer $\mathrm{Pt_{2}HgSe_{3}}$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Muzamil Shah, Imtiaz Khan, Kashif Sabeeh, Muhammad Sabieh Anwar, Reza Asgari
We present a theoretical framework to investigate quantum magnetotransport in monolayer jacutingaite, focusing on its response to external electric fields and off-resonant circularly polarized laser irradiation. Our analysis reveals a sequence of topological phase transitions triggered by tuning these external parameters. We find that the zeroth LL exhibits spin- and valley-polarized splitting, leading to four distinct peaks in the DOSs for the $ K$ and $ K’$ valleys. Using the Kubo formalism, we calculate both longitudinal and Hall magneto-optical conductivities based on the Kane-Mele model. Our results demonstrate that external electric, magnetic, and off-resonant optical fields can control these conductivities. These findings highlight monolayer jacutingaite as a highly tunable platform with strong potential for future applications in photonics, optoelectronics, and topological quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Construction of Kondo Chains by Engineering Porphyrin π-Radicals on Au(111)
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Yan Zhao, Kaiyue Jiang, Peng-Yi Liu, Ruoning Li, Jie Li, Xin Li, Xinchen Fang, Anjing Zhao, Yutong Zhu, Hongxiang Xu, Ting Chen, Dong Wang, Xiaodong Zhuang, Shimin Hou, Kai Wu, Song Gao, Qing-Feng Sun, Yajie Zhang, Yongfeng Wang
Quantum manipulation of molecular radical spins provides a crucial platform for exploring emergent phenomena in many-body systems. Here, we combine surface-confined synthesis with scanning tunneling microscopy (STM) tip-induced dehydrogenation to achieve atom-precise engineering of quasi-one-dimensional porphyrin-based Kondo chains (1-7 units) on Au(111). Key design innovations leverage large-sized porphyrins to suppress intrachain antiferromagnetic coupling, while $ {Zn}^{2+}$ chelation at porphyrin cores enhances molecule-substrate interactions to amplify Kondo effect. High-resolution STS measurements and low-energy effective modeling collectively demonstrate that $ {\pi}$ -radicals at each fused-porphyrin unit form Kondo singlets screened by conduction electrons. Adjacent singlets develop direct coherent coupling via quantum-state-overlap-enabled electron tunneling. Crucially, chiral symmetry in the effective model governs zero-mode distribution-present in odd-length chains yet absent in even-length chains-which dictates pronounced odd-even quantum effects in STS spectra of finite chains. Furthermore, geometric control emerges through conformational distortions modulated by chain fusion width. This enables directional tuning of the competition between Kondo screening and magnetic exchange. Tilted single/fused-triple-porphyrin chains weaken spin exchange through enhanced Kondo coupling, while parallel fused-double-porphyrin chains suppress Kondo screening via increased spin exchange. This opposing modulation of Kondo versus exchange interactions establishes an inverse control paradigm. This work simultaneously resolves the dimensional dependence of many-body correlations in confined quantum systems and pioneers approaches for quantum-critical manipulation in molecular spin architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Learning Chaotic Dynamics with Neuromorphic Network Dynamics
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-13 20:00 EDT
Yinhao Xu, Georg A. Gottwald, Zdenka Kuncic
This study investigates how dynamical systems may be learned and modelled with a neuromorphic network which is itself a dynamical system. The neuromorphic network used in this study is based on a complex electrical circuit comprised of memristive elements that produce neuro-synaptic nonlinear responses to input electrical signals. To determine how computation may be performed using the physics of the underlying system, the neuromorphic network was simulated and evaluated on autonomous prediction of a multivariate chaotic time series, implemented with a reservoir computing framework. Through manipulating only input electrodes and voltages, optimal nonlinear dynamical responses were found when input voltages maximise the number of memristive components whose internal dynamics explore the entire dynamical range of the memristor model. Increasing the network coverage with the input electrodes was found to suppress other nonlinear responses that are less conducive to learning. These results provide valuable insights into how a practical neuromorphic network device can be optimised for learning complex dynamical systems using only external control parameters.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Artificial Intelligence (cs.AI), Emerging Technologies (cs.ET)
37 pages, 22 figures
Dirac edge states of two-dimensional altermagnetic topological crystalline insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Raghottam M. Sattigeri, Xujia Gong, Amar Fakhredine, Carmine Autieri, Giuseppe Cuono
Two-dimensional (2D) metallic altermagnets present exciting opportunities for both fundamental research and practical innovations. Their ability to enhance tunneling magnetoresistance in magnetic tunnel junctions, combined with the direct control of spin currents via electric fields, makes them highly promising for spintronic devices. Moreover, the rich electronic structure of altermagnets can host nontrivial topological phases. In particular, topological crystalline insulators are compounds where the topological states are protected by both crystalline and time-reversal symmetries. Furthermore, manipulating the state of a system between topological and trivial phases through external parameters unlocks new possibilities for quantum materials and advanced electronics. We show the edge states of a 2D altermagnetic topological crystalline insulator, using as a representative example Cr$ _2$ BAl, a 2D MBene metallic altermagnet with a d$ _{x^2-y^2}$ altermagnetic ordering. We find that the system can host an altermagnetic phase with extremely large ``weak ferrimagnetism” which is sizeable also with light atoms, only with an in-plane component of the Néel vector. The electronic structure of Cr$ _2$ BAl presents multiple crossings and anti-crossings in the vicinity of the Fermi level along [100] and [010] directions. When the spin-orbit coupling interaction is included, with the Néel vector along [001] direction, energy gaps open at the band crossing points, resulting in a pronounced peak in the spin Hall conductivity. The simulated Cr-B terminated [100] edge-projected band structure reveals Dirac dispersions at the bulk crossings and anti-crossings, which are absent in Cr-Al terminations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures
Deterministic Switching of the Néel Vector by Asymmetric Spin Torque
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Shui-Sen Zhang, Zi-An Wang, Bo Li, Wen-Jian Lu, Mingliang Tian, Yu-Ping Sun, Haifeng Du, Ding-Fu Shao
Néel vector, the order parameter of collinear antiferromagnets, serves as a state variable in associated antiferromagnetic (AFM) spintronic devices to encode information. A deterministic switching of Néel vector is crucial for the write-in operation, which, however, remains a challenging problem in AFM spintronics. Here we demonstrate, based on analytical derivation and macro-spin simulations, that Néel vector switching can be generally achieved via a current-induced spin torque, provided the spin accumulations responsible for this torque are non-identical between opposite sublattices. This condition occurs widely in AFM films, as symmetry equivalence between sublattice-dependent spin accumulations is usually absent, allowing unequal spin accumulations induced by Edelstein effect or a spin current. The consequent asymmetric spin torque leads to Néel vector dynamics fundamentally different from previous expectations. The switching conditions derived analytically agree well with simulation results and suggest various directions for further optimization. Our work establishes a general mechanism for current-induced Néel vector switching, which is in principle feasible for all collinear antiferromagnets, and thus paves the route to realize efficient writing in antiferromagnetic spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Comments are welcome
From stripes to hexagons: strain-induced 2D Pb phases confined between graphene and SiC
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Markus Gruschwitz, Sergii Sologub, Chitran Ghosal, Zamin Mamiyev, Yuran Niu, Alexei Zakharov, Christoph Tegenkamp
The intercalation of metals beneath graphene offers a powerful route to stabilizing and protecting novel two-dimensional (2D) phases. The epitaxial growth of Pb monolayers on SiC(0001), combined with the relatively large spacing of the suspended graphene, makes this system particularly distinctive. Using low-energy electron diffraction (LEED) and various microscopy techniques – including scanning electron microscopy (SEM), scanning tunneling microscopy (STM), and low-energy electron microscopy (LEEM) – we have investigated the intercalation process across multiple length scales. Our analysis reveals the formation of different 2D Pb monolayer phases, such as stripes and hexagons, which emerge due to the interplay between substrate pinning and strain within the Pb layer, depending on local coverage. These findings provide new insights into the strain-driven stabilization of intercalated metal layers and highlight the potential of graphene as a versatile platform for engineering low-dimensional materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Comment on “Electric conductivity of graphene: Kubo model versus a nonlocal quantum field theory model (arXiv:2403.02279v3)”
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
M.Bordag, N.Khusnutdinov, G.L.Klimchitskaya, V.M.Mostepanenko
Recently, Rodriguez-Lopez, Wang, and Antezza [arXiv:2403.02279v3; Phys. Rev. B v.111, 115428 (2025)] compared the theoretical descriptions of electric conductivity of graphene given by the Kubo model and quantum field theory in terms of the polarizationtensor. According to these authors, in the spatially nonlocal case, the quantum field theoretical description contains ``hard inconsistencies”. To bring the predictions of quantum field theory in agreement with those following from the Kubo model, the modified expression was used which relates the conductivity and the polarization tensor. Here, it is shown that this modification violates the the requirement of gauge invariance and, thus, is unacceptable. By comparing both theoretical approaches, we demonstrate that all the results obtained within quantum field theory are physically well justified whereas an application of the modified expression for the conductivity of graphene leads to the consequences of nonphysical character.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
5 pages; comment on arXiv:2403.02279v3
Surface Nematic Quasi-Uniformity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-13 20:00 EDT
Andrea Pedrini, Epifanio G. Virga
Line fields on surfaces are a means to describe the nematic order that may pattern them. The least distorted nematic fields are called uniform, but they can only exist on surfaces with negative constant Gaussian curvature. To identify the least distorted nematic fields on a generic surface, we relax the notion of uniformity into that of quasi-uniformity and prove that all such fields are parallel transported (in Levi-Civita’s sense) by the geodesics of the surface. Both global and local constructions of quasi-uniform fields are presented to illustrate both richness and significance of the proposed notion.
Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph), Differential Geometry (math.DG)
Generalized Modulated Symmetries in $\mathbb{Z}_2$ Topological Ordered Phases
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Gustavo M. Yoshitome, Heitor Casasola, Rodrigo Corso, Pedro R. S. Gomes
We study $ \mathbb{Z}_2$ topological ordered phases in 2+1 dimensions characterized by generalized modulated symmetries. Such phases have explicit realizations in terms of fixed-point Hamiltonians involving commuting projectors with support $ h=3,5,7,\ldots$ in the horizontal direction, which dictates the modulation of the generalized symmetries. These symmetries are sensitive to the lattice sizes. For certain sizes, they are spontaneously broken and the ground state is degenerated, while for the remaining ones, the symmetries are explicitly broken and the ground state is unique. The ground state dependence on the lattice sizes is a manifestation of the ultraviolet/infrared (UV/IR) mixing. The structure of the modulated symmetries implies that the anyons can move only in rigid steps of size $ h$ , leading to the notion of position-dependent anyons. The phases exhibit rich boundary physics with a variety of gapped phases, including trivial, partial and total symmetry-breaking, and SPT phases. Effective field theory descriptions are discussed, making transparent the relation between the generalized modulated symmetries and the restrictions on anyon mobility, incorporating the boundary physics in a natural way, and showing how the short-distance details can be incorporated into the continuum by means of twisted boundary conditions.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
59 pages, 11 figures
Automated All-RF Tuning for Spin Qubit Readout and Control
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Cornelius Carlsson, Jaime Saez-Mollejo, Federico Fedele, Stefano Calcaterra, Daniel Chrastina, Giovanni Isella, Georgios Katsaros, Natalia Ares
Efficient tuning of spin qubits remains a major bottleneck in scaling semiconductor quantum dot-based quantum processors. A key challenge is the rapid identification of gate voltage regimes suitable for qubit initialisation, control, and readout. Here, we leverage radio-frequency charge sensing to automate spin qubit tuning, achieving a median tuning time of approximately 15 minutes. In a single continuous run, our routine identifies spin qubits at 12 distinct charge transitions in under 17 hours. Beyond tuning, our routine autonomously acquires data revealing the gate-voltage dependence of the exchange interaction, dephasing time, and quality factor – quantities that vary substantially between charge configurations. These results represent a step change in high-throughput spin qubit tuning and provide a foundation for a systematic and automated exploration of semiconductor quantum circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Failure modes of irregular ceramic foam under compression: Development of a new image based strut segmentation strategy
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-13 20:00 EDT
Vinit Vijay Deshpande, Romana Piat
The work investigates the failure modes of the microstructure of an irregular ceramic foam subjected to uniaxial compression loading. The foam material is manufactured using the direct foaming method and has polydispersed pores homogeneously distributed in the microstructure. The effective stress-strain curve and the macroscopic strength of the material differs significantly with the predictions of the Gibson-Ashby model that assumes a regular microstructure. The objective of this work is to determine the reasons. The work builds upon an image segmentation algorithm that utilizes a skeletonization method followed by geometric pruning strategies to isolate the struts in the foam microstructure. In this work, a novel pruning strategy defined by a physics-based significance measure is proposed, which identifies the struts whose failure leads to macroscopic failure of the material. The stresses in the struts are calculated by a finite element simulation, which is then utilized to determine their failure modes. This also reveals the relationship between the strut orientation and their failure this http URL energy dissipated by the individual failure modes as the loading is increased shows that there are two dominant modes which are different from the bending failure reported in the Gibson-Ashby model. These failure modes are mixed compression-tension and pure compression.
Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph)
Photonic chiral bulk transports manipulated by boundary freedom in three-dimensional meta-crystals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-13 20:00 EDT
Yingxin Qi, Hanyu Wang, Qinghua Guo, Zhihong Zhu, Biao Yang
In topological physics, one of the most intriguing phenomena is the presence of topological boundary states, accurately predicted by the well-established bulk-edge correspondence. For example, in three-dimensional Weyl semimetals, Fermi arcs emerge to connect projected Weyl points on the surface due to inheriting the bulk-edge correspondence from the integer quantum Hall effect. However, limited attention has been paid to exploring the reverse mechanism in topological crystals. In this study, we propose that boundaries can serve as an alternative degree of freedom to manipulate topological bulk transports. We analytically and experimentally validate our concept using a finite-thickness photonic meta-crystal that supports bulk nodal lines, with its zeroth modes exhibiting opposite chiral bulk transports under different boundary conditions. Notably, the mirror symmetry remains preserved across both configurations. These findings are applicable to other topological systems, providing new insights into systems with varied boundary conditions and offering the potential for the design of more compact and spatially efficient topological photonic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
Prediction and control of geometry-induced nematic order in growing multicellular systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-13 20:00 EDT
Lukas Hupe, Jonas Isensee, Ramin Golestanian, Philip Bittihn
In densely-packed two-dimensional systems of growing cells, such as rod-shaped bacteria, a number of experimental and numerical studies report distinct patterns of nematic orientational order in the presence of confinement. So far, these effects have been explained using variations of growing active nematic continuum theories, which incorporate feedback between growth-induced active stresses, the resulting material flow and nematic orientation, and were adapted to the specific geometry under investigation. Here, we first show that a direct, analytical prediction of orientation patterns based on a simple isotropic-growth assumption and the shear rate tensor of the expansion flow already covers previously observed cases. We use this method to tune orientation patterns and net topological defect charge in a systematic way using domain geometry, confirmed by agent-based simulations. We then show how this framework can be extended to quantitatively capture alignment strength, and explore its potential for cross-prediction across different geometries. Our simplified and unifying theoretical framework highlights the role of domain geometry in shaping nematic order of growing systems, and thereby provides a way to forward-engineer desired orientation patterns.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
12 pages, 6 figures
Intrinsic defects and 4d/5d transition metal defects in Cr$_2$O$_3$: pathways to enhance the Néel temperature
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
First-principles calculations are employed to explore avenues to increase the Néel temperature ($ T_{\mathrm{N}}$ ) of the magnetoelectric antiferromagnet Cr$ _2$ O$ 3$ through doping. Employing the hybrid functional method, we calculate the formation energy of intrinsic defects and transition metal dopants (Mo, W, Nb, Ta, Zr, and Hf) to assess their likelihood of formation. Intrinsic defect calculations indicate that Cr interstitials and oxygen vacancies dominate under Cr-rich conditions, whereas Cr vacancies prevail under O-rich conditions. Notably, under Cr-rich conditions, the Fermi level can be pinned slightly above mid-gap due to the formation of Cr interstitials and oxygen vacancies. To assess the influence of dopant on $ T{\mathrm{N}}$ of Cr$ _2$ O$ 3$ , we calculate the enhancement of the exchange energy for the spin on the dopant site or on adjacent Cr site using the supercell method. Our study identifies isovalent Mo and W substitution on Cr site as the most promising candidates to increase Néel temperature due to the impurity-mediated enhanced exchange interaction for half-filled bands. Formation energy calculations indicate that Mo and W substitution on Cr are easier to form under Cr-rich conditions and a Fermi level near or slightly above the midgap renders a desirable neutral Mo and W defect. This is assisted by the formation of intrinsic Cr interstitial and O vacancy under Cr-rich conditions. These findings offer a route to utilize defects for higher $ T{\mathrm{N}}$ and enhanced performance of Cr$ _2$ O$ _3$ in magnetoelectric devices and furnish invaluable insights for directing subsequent experimental endeavors.
Materials Science (cond-mat.mtrl-sci)
12 pages, 11 figures
Exact zero modes in the interacting Majorana X- and Y-junctions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Rik Mulder, Bowy M. La Rivière, Natalia Chepiga
We report the appearance of exact zero modes in junctions of interacting Majorana wires. We consider two, three and four short Majorana chains coupled to each other at one edge and forming a longer chain with an impurity bond, Y- and X- junctions correspondingly. The exact zero modes emerge as a result of incommensurate short-range correlations resulting from interacting Majorana fermions and manifest themselves as unavoided crossing of energy levels of in-gap states continuously tuned by hopping and interaction strength. For the Y- and X-junctions, we detect four in-gap states that are clearly visible below the bulk excitations. In the X-junction, the energy levels cross pairwise; in the Y-junction, the crossings happen simultaneously in all four levels. We argue that this peculiarity is a result of fractional degrees of freedom localized at the center of junctions with an odd number of arms, which mediate the interaction of the outer edge states. Furthermore, we show that zero modes in multiple-arm junctions can be effectively modeled by a single chain with a strong impurity bond.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 8 figures (5 in main text, 3 in appendices)
Physical properties of $R$Co${2}$Al${8}$ ($R=$ La, Ce, Pr, Nd and Sm) single crystals: an emerging structure-type for anisotropic Kondo lattice studies
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Fernando A. Garcia, Sushma Kumari, Juan Schmidt, Cris Adriano, Aashish Sapkota, Paul C. Canfield, Rebecca Flint, Raquel A. Ribeiro
Systematic investigations of rare-earth ($ R$ ) based intermetallic materials is a leading strategy to reveal the underlying mechanisms governing a range of physical phenomena, such as the formation of a Kondo lattice and competing electronic and magnetic anisotropies. In this work, the magnetic, thermal and transport properties of $ R$ Co$ {2}$ Al$ {8}$ ($ R=$ La, Ce, Pr, Nd and Sm) single crystals are presented. LaCo$ {2}$ Al$ {8}$ is characterized as a Pauli paramagnet and transport measurements, with the current along and perpendicular to the orthorhombic $ c$ -axis ($ \rho{c}$ and $ \rho{ab}$ , respectively), reveal a clear electronic anisotropy, with $ \rho{ab }\approx(4-7)\rho{c }$ at $ 300$ K. We show that CeCo$ {2}$ Al$ {8}$ is a Kondo-lattice for which the Kondo coherence temperature $ T{\text{K}}^{\ast}$ , deduced from broad maximums in $ \rho{c}$ and $ \rho_{ab}$ at $ \approx$ 68 and 46 K, respectively, is also anisotropic. This finding is related to a possible underlying anisotropy of the Kondo coupling in CeCo$ _{2}$ Al$ _{8}$ . The Pr and Nd-based materials present strong easy-axis anisotropy ($ c$ -axis) and antiferromagnetic (AFM) orders below $ T=4.84$ K and $ T=8.1$ K, respectively. Metamagnetic transitions from this AFM to a spin-polarized paramagnetic phase state are investigated by isothermal magnetization measurements. The Sm-based compound is also an easy-axis AFM with a transition at $ T=21.6$ K.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
13 pages, 8 figures, submitted to Physical Review B
Physics-informed Machine Learning Analysis for Nanoscale Grain Mapping by Synchrotron Laue Microdiffraction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Ka Hung Chan, Xinyue Huang, Nobumichi Tamura, Xian Chen
Understanding the grain morphology, orientation distribution, and crystal structure of nanocrystals is essential for optimizing the mechanical and physical properties of functional materials. Synchrotron X-ray Laue microdiffraction is a powerful technique for characterizing crystal structures and orientation mapping using focused X-rays. However, when grain sizes are smaller than the beam size, mixed peaks in the Laue pattern from neighboring grains limit the resolution of grain morphology mapping. We propose a physics-informed machine learning (PIML) approach that combines a CNN feature extractor with a physics-informed filtering algorithm to overcome the spatial resolution limits of X-rays, achieving nanoscale resolution for grain mapping. Our PIML method successfully resolves the grain size, orientation distribution, and morphology of Au nanocrystals through synchrotron microdiffraction scans, showing good agreement with electron backscatter diffraction results. This PIML-assisted synchrotron microdiffraction analysis can be generalized to other diffraction-based probes, enabling the characterization of nanosized structures with micron-sized probes.
Materials Science (cond-mat.mtrl-sci), High Energy Physics - Lattice (hep-lat)
8 pages, 5 figures
From Fractionalization to Chiral Topological Superconductivity in Flat Chern Band
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-13 20:00 EDT
Daniele Guerci, Ahmed Abouelkomsan, Liang Fu
We show that interacting electrons in a flat Chern band can form, in addition to fractional Chern insulators, a chiral $ f$ -wave topological superconductor that hosts neutral Majorana fermion edge modes. Superconductivity emerges from an interaction-induced metallic state that exhibits anomalous Hall effect, as observed in rhombohedral graphene and near the $ \nu=\frac{2}{3}$ fractional Chern insulator in twisted transition metal dichalcogenides.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
7+9 pages, 5+6 figures
Coupled reaction and diffusion governing interface evolution in solid-state batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Jingxuan Ding, Laura Zichi, Matteo Carli, Menghang Wang, Albert Musaelian, Yu Xie, Boris Kozinsky
Understanding and controlling the atomistic-level reactions governing the formation of the solid-electrolyte interphase (SEI) is crucial for the viability of next-generation solid state batteries. However, challenges persist due to difficulties in experimentally characterizing buried interfaces and limits in simulation speed and accuracy. We conduct large-scale explicit reactive simulations with quantum accuracy for a symmetric battery cell, {\symcell}, enabled by active learning and deep equivariant neural network interatomic potentials. To automatically characterize the coupled reactions and interdiffusion at the interface, we formulate and use unsupervised classification techniques based on clustering in the space of local atomic environments. Our analysis reveals the formation of a previously unreported crystalline disordered phase, Li$ _2$ S$ _{0.72}$ P$ _{0.14}$ Cl$ _{0.14}$ , in the SEI, that evaded previous predictions based purely on thermodynamics, underscoring the importance of explicit modeling of full reaction and transport kinetics. Our simulations agree with and explain experimental observations of the SEI formations and elucidate the Li creep mechanisms, critical to dendrite initiation, characterized by significant Li motion along the interface. Our approach is to crease a digital twin from first principles, without adjustable parameters fitted to experiment. As such, it offers capabilities to gain insights into atomistic dynamics governing complex heterogeneous processes in solid-state synthesis and electrochemistry.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
Apparent inconsistency between Streda formula and Hall conductivity in reentrant integer quantum anomalous Hall effect in twisted MoTe$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-13 20:00 EDT
Yi Huang, Seth Musser, Jihang Zhu, Yang-Zhi Chou, Sankar Das Sarma
Recent experiments in twisted bilayer MoTe$ _2$ (tMoTe$ _2$ ) have uncovered a rich landscape of correlated phases. In this work, we investigate the reentrant integer quantum anomalous Hall (RIQAH) states reported in F. Xu, et. al., arXiv:2504.06972 which displays a notable mismatch between the Hall conductivity measured via transport and that inferred from the Streda formula. We argue that this discrepancy can be explained if the RIQAH state is a quantum Hall bubble phase, analogous to similar well-established phenomena in 2D GaAs quantum wells. While this explains the RIQAH state at a filling $ \nu = -0.63$ , the other RIQAH state at $ \nu = -0.7$ has a smaller slope necessitating a different interpretation. We propose that this discrepancy arises due to a nearby resistive peak masking the true slope. Furthermore, we identify this resistive peak as a signature of a magnetic phase transition near $ \nu = -0.75$ , possibly driven by a Van Hove singularity. The anomalous Hall response and Landau fan evolution across this transition suggest a change in Fermi surface topology and a phase with zero Chern number, potentially corresponding to an inter-valley coherent state. These observations offer new insights into the nature of the RIQAH states and raise the possibility that the nearby superconducting phase may have an inter-valley coherent normal state.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 3 figures
FerroAI: A Deep Learning Model for Predicting Phase Diagrams of Ferroelectric Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-13 20:00 EDT
Composition-temperature phase diagrams are crucial for designing ferroelectric materials, however predicting them accurately remains challenging due to limited phase transformation data and the constraints of conventional methods. Here, we utilize natural language processing (NLP) to text-mine 41,597 research articles, compiling a dataset of 2,838 phase transformations across 846 ferroelectric materials. Leveraging this dataset, we develop FerroAI, a deep learning model for phase diagram prediction. FerroAI successfully predicts phase boundaries and transformations among different crystal symmetries in Ce/Zr co-doped BaTiO$ 3$ (BT)-$ x$ Ba$ {0.7}$ Ca$ _{0.3}$ TiO$ _3$ (BCT). It also identifies a morphotropic phase boundary in Zr/Hf co-doped BT-$ x$ BCT at $ x = 0.3$ , guiding the discovery of a new ferroelectric material with an experimentally measured dielectric constant of 9535. These results establish FerroAI as a powerful tool for phase diagram construction, guiding the design of high-performance ferroelectric materials.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
10 pages, 8 figures, 2 tables