CMP Journal 2026-10-28
Statistics
arXiv: 115
arXiv
Same-spin correlation screens the exchange peak of the electron gas near 2kF
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Exchange alone gives the electron gas a local field factor with a sharp peak just below 2kF. Quantum Monte Carlo finds none. Both spin channels are computed here from their lowest diagrams with a dynamically screened interaction and no fitting. Parallel spin correlation is the negative image of exchange and removes about half the peak; the calculated spin-resolved factors account for the QMC data at rs = 1 and 2, and at q = 0 for the compressibility and spin susceptibility obtained from the ground-state energy. The two classes of diagrams are the two terms of the kernel of Hedin’s vertex equation, of which the second is routinely dropped.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 3 figures
An exactly solvable obstructed seam on a lattice Klein bottle: bulk-locked Majorana rings and register-dependent toric codes
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
We study a frustrated seam produced by literal reflection gluing of Wen’s plaquette model on a closed lattice Klein bottle. The seam operators anticommute along two cycles for even circumference and one cycle of twice the length for odd circumference. Their algebra reduces to free Majorana rings, while the commuting bulk stabilizers constrain the allowed ring sectors. This bulk locking yields exact ground energies, excitation gaps and degeneracies, checked by phase-aware Pauli traces and finite-size diagonalization, including two 24-qubit energy predictions. The seam degeneracy is not topological: the single-site seam fields tested split it at second order. We contrast this obstructed gluing with consistent toric-code realizations. An edge register preserves the anyon labels; a Hadamard-dressed site register has colour-dependent seam transport, with ground-state degeneracy 2 or 4 for even circumference and a sign-frustrated exception at odd circumference. For the enumerated lattice isometries and sizes, we compute logical gates and distances, distinguishing abstract qubit relabelling from local hardware depth. Finally, on three 16- and 24-qubit lattices, chiral matter selects a holonomy doublet whose electric-field splitting follows two competing tunnelling routes. These matter results remain finite-size statements. The main result is the exact obstructed-seam solution with bulk sector locking; the register, gate and matter calculations delimit its relation to topological codes.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
19 pages, 5 figures. Reproducibility archive: this https URL
Agentic Swarms Discover Enhanchment of Fractional Chern Insulator Gaps Beyond Ideal Quantum Geometry
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Yitong Zhang, Changwen Xu, Andrew Boshi Li, Siddhartha Sarkar, Kai Sun, Venkatasubramanian Viswanathan
Can artificial intelligence (AI) move beyond solving well-defined problems to contribute to open-ended discovery in fundamental physics? Could AI propose what to explore, identify unexpected phenomena, and uncover their mechanisms? We address this using MOSAIC (Multi-agent Open-ended Scientific Analysis and Investigation through Collaboration), a collaborative swarm of AI agents (Claude Opus 5.5), to tackle a longstanding bottleneck: the small energy gaps limiting the robustness of fractional topological order and the study of anyons at higher temperatures. Rather than prescribing a model, we ask frontier models (GPT-6 Astra) to propose a theoretical framework, which MOSAIC explores through diverse strategies and rapid exchange of ideas. This reveals a striking finding: although ideal quantum geometry is considered favorable for fractional states, departing from this limit can dramatically enhance their robustness, with many-body gaps more than an order of magnitude larger than in the ideal case. Without centralized coordination, the agents explored autonomously, combined findings across agents, and formed insights from individual runs, outperforming isolated agents with the same tools. AI-assisted theoretical analysis further develops simplified models with an analytical gap enhancement factor that is unbounded within the single-band approximation. Remarkably, AI identifies the real-space quantum metric, rather than the momentum-space one, as the key quantity governing the many-body gap, revealing how flat-band wavefunctions shape two-electron interactions and yielding an index computable from single-particle wavefunctions without many-body ED to guide gap optimization. Our study demonstrates how collaborative AI agents can integrate exploration, discovery of unexpected physics, and theoretical understanding, opening new possibilities for AI-driven research in fundamental physics.
Strongly Correlated Electrons (cond-mat.str-el)
27 pages; 37 pages of Supporting Information
Planckian dissipation per unit critical entropy as a coupling-free probe of the strange-metal bath
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Strange metals pair a resistivity linear in temperature with a specific heat $ C/T$ rising logarithmically on cooling. We find that, if electrons scatter off a local critical bath, the coupling cancels in the ratio $ Q$ of their coefficients, leaving two measurable numbers: how slowly the bath relaxes, seen in photoemission or optics, and the share of critical entropy that relaxes current. Baths form classes: $ Q\le4.91$ for a conformal bath, as SYK models confirm; 9–15 for the Yukawa–SYK field; and far less for Kondo lattices. LSCO, at $ Q\approx9$ , exceeds the conformal bound, pointing to the Yukawa–SYK field.
Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 9 figures
Machine learning enabled design of sustainable alloys considering real world constraints
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Quan Li, Zhilong Wang, Lei Shi, Baojing Feng, Changhui Liu, Jie Wang, Jingya Wang, Weisen Zheng, Matic JovicevicKlug, Ziyuan Rao, Jinjin Li, Dierk Raabe, Xiaoqin Zeng
Designing sustainable alloys must reconcile high performance with real-world constraints, including feedstock scarcity and variability, processing and energy requirements, regulatory thresholds, and economic limitations. Addressing these constraints reaches far beyond today’s conventional performance-focused frameworks. It needs to consider not only complex property-processing-performance trade-offs but also sustainable production pathways. Here, we propose a physics-informed ensemble (PIE) learning framework that integrates fundamental structure-property relationships with processing routes and sustainability criteria for mechanism-based alloy design. It predicts properties from composition-microstructure relationships and infers processing routes under sustainability constraints, establishing an interdisciplinary approach to identifying sustainable alloy solutions. We validate the approach for Mg alloys, a lightweight yet energy-intensive metallic material class, considering performance, cost, and carbon emissions. Trained on a benchmark dataset, the PIE model systematically explores plausible alloy compositions and microstructures to construct a digital library of millions of candidate alloys. From this space, we identify two sustainable Mg alloy solutions that overcome the conventional performance-cost-emission trade-off: a rare-earth-containing alloy increases yield and tensile strength by 72.8 percent and 61.1 percent, respectively, over alloys from the same family at comparable cost and emissions; and a rare-earth-free alloy reduces cost and carbon emissions by 40.4 percent and 88.9 percent, respectively, relative to its primary-feedstock counterpart, without compromising mechanical performance. This work introduces a general, physics-informed, and quantifiable framework for designing sustainable alloys under real-world constraints.
Materials Science (cond-mat.mtrl-sci)
26 pages
Bayesian Inference in Partially Observed Critical Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
We ask how much of a large random system must be observed before a global average can be inferred with controlled uncertainty. For the random transposition shuffle, a conjugate Bayesian estimator of the average displacement, computed from $ m$ uniformly sampled cards, has relative uncertainty $ 1/\sqrt{2m}$ , independent of the deck size $ n$ . The law of total variance exposes a second error, the floor $ R_n$ , which arises because the observed configuration is a single draw from equilibrium: no relative tolerance below $ \kappa\sqrt{R_n}$ can be certified, even by a census. For the shuffle we derive $ R_n=(2n^2+7)/\bigl(5(n-1)^2(n+1)\bigr)$ and show that the posterior remains calibrated. At the critical point of the two-dimensional Ising model the floor of the energy vanishes, whereas that of the magnetisation stays near $ 0.072$ ; its mean-field limit is $ \sqrt{2}-1$ . For correlated fields read by sensor networks, the usual 95% interval covers the ensemble mean in 7% of cases. Bounding the floor from one realisation, as in single-chain Monte Carlo diagnostics, requires an assumption on the decay of correlations.
Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)
Tunable turning point of the frequency–temperature response in suspended bilayer SiN_x/Al nanofilms
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Yanli Shi, Hui Wu, Guangyu Li, Zhuo Miao, Luyao Zhu, Chen Zheng, Weidong Zheng, Qun Cao, Zhe He, Zheng Cui
Non-invasive thermometry is highly desirable in cryogenic experiments to avoid the self-heating inherent in conventional sensors. In previous work, temperature was probed via the vibrational eigenfrequency of a suspended single-layer SiNx nanofilm. However, the turning point of the frequency-temperature curve limited the usable measurement range. Moreover, the slow thermal response confined measurements to a stepwise protocol with only discrete temperature points. Here, we show that these limitations can be overcome with a suspended bilayer SiNx/Al nanofilm, whose temperature-dependent vibrational eigenfrequency provides a monotonic, continuous, and repeatable temperature readout. The frequency-temperature dependence is governed by the mismatch between the effective coefficients of thermal expansion (CTE) of the bilayer and the substrate, which makes the turning point tunable through the thickness ratio of the two layers. Over the 90 K to 300 K range, we characterize three bilayer nanofilms with different Al layer thicknesses and show how the turning point shifts with the thickness of the Al layer. For the sample with 72 nm Al, the turning point is pushed beyond 300 K, yielding a monotonic negative temperature coefficient over the entire 90 K to 300 K range. Combining a thin Al layer on the SiNx film with improved thermal anchoring of the chip shortens the thermal response to below 1 s, enabling continuous frequency tracking at a ramp rate of 3 K/min. We also demonstrate that the nanofilm with a 72 nm Al layer achieves a repeatability better than 150 mK above 175 K, and the frequency resolution of 1 Hz corresponds to a temperature resolution of ~5 mK.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Optics (physics.optics)
Cutting, Shuffling and Diffusion as a Coarsening Process
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Daniel Lester, Tanguy LeBorgne, Joris Heyman
Cutting and shuffling (CS) rearranges fluid without stretching, but homogenisation requires diffusion (D); this interaction is not well understood. We show that CSD is a coarsening process, with scale $ \bar\ell=L(n_c\mathrm{Pe}/2)^{-1/3}$ rather than the Batchelor scale, and that cutting acts as a fractional Laplacian in wavenumber, giving the exact mixing rate $ \gamma=2^{1/3}|a_1’|n_c^{2/3}\lambda\mathrm{Pe}^{-1/3}$ for $ n_c$ cuts per event at rate $ \lambda$ , with $ a_1’=-1.0188\dots$ the first zero of $ \mathrm{Ai}’$ . This holds in any dimension for random and deterministic protocols, extends to finite-time mixing, and places CSD in a known non-equilibrium universality class.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD), Fluid Dynamics (physics.flu-dyn)
6 pages, 5 figures
Amorphization-Depth-Dependent Bismuth Redistribution and Activation in Silicon for Quantum Devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Youcef A. Bioud, Simon-Jean Michel, Sebastien Francoeur, Sjoerd Roorda, Eva Dupont-Ferrier
Near-surface bismuth donors are promising for silicon quantum devices because of their rich electron-nuclear spin structure and long spin coherence, but their electrical activation is strongly influenced by implantation-induced amorphization. We compare redistribution and electrical activation of 20 keV Bi implanted directly into Si and after Si preamorphization. The two routes produce amorphous-layer depths of approximately 47 nm and 177 +/- 15 nm, respectively. After annealing at 650 C for 300 s, Rutherford backscattering spectrometry and channeling reveal comparable substitutional Bi fractions of 91 +/- 2% and 89 +/- 4%, whereas Hall measurements indicate Hall-derived electrical activation yields of approximately 60% and 90%, respectively. Depth-resolved ion-scattering analysis reveals a buried Bi-related feature at or beyond the initial amorphous/crystalline interface, within the end-of-range region, together with increasing surface segregation at higher annealing temperatures. The buried feature is consistent with trapping near residual end-of-range defects. X-ray photoelectron spectroscopy and low-temperature photoluminescence on the Bi-only sample reveal no resolvable Bi-oxide contribution and a donor-related optical signature, respectively. These results show that amorphization depth and regrowth geometry govern Bi redistribution and influence electrical activation beyond substitutional incorporation alone.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
AlgebrasTQD: Computing Algebras and Interfaces in Twisted Quantum Doubles
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
We present AlgebrasTQD, an open-source code written in GAP (Groups, Algorithms, and Programming), for computing condensable algebras and the corresponding topological boundaries and interfaces of twisted quantum doubles $ D^\omega(G)$ . These algebras can be used to classify 1+1d gapped and gapless phases whose symmetry is related by gauging to a finite group $ G$ with anomaly $ \omega\in H^3(G,U(1))$ , to study 2+1d anyon proliferation and to construct logical gates in non-Abelian topological quantum codes. The functions in AlgebrasTQD compute all condensable algebras $ A(H,F,\gamma,\epsilon)$ with their algebra structure and anyons, sort them into isomorphism classes and identify the twin algebras that are inequivalent but share the same anyon decomposition. AlgebrasTQD also determines all the subalgebra relations, the corresponding Hasse diagram and the types of 1+1d phases for any chosen, possibly non-invertible, group-theoretical symmetry. For non-maximal algebras, the code computes the reduced topological order with its $ 3$ -cocycle and the map of anyons across the topological interface. Finally, AlgebrasTQD includes functions that construct certain non-Clifford logical gates via non-Abelian surface codes. We summarize the formulas that are implemented in the AlgebrasTQD code, and we illustrate its use with Abelian and non-Abelian groups including $ \mathbb{Z}2^3$ with $ \omega\text{III}$ , $ D_8$ , $ A_4$ with and without anomaly, twin algebras and twin phases, and the Clifford-hierarchy gates in quantum doubles of dihedral groups. All arithmetic is exact and AlgebrasTQD can be used with any finite group $ G$ and 3-cocycle $ \omega$ , limited only by the time and size of the calculation. The code is available at this https URL
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Algebra (math.QA), Quantum Physics (quant-ph)
38 pages, companion paper to the code at this https URL
Emergent Fermi Surfaces in Periodically Driven Bose Gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
Li-kun Shi, Oles Matsyshyn, Inti Sodemann Villadiego
We show that the steady state of a periodically driven Bose gas coupled to a thermal bath features emergent Fermi surfaces both in its high temperature and Bose-Einstein-condensate (BEC) states. These emergent Fermi surfaces are non-analyticities in the occupation function as a function of momentum arising from the lack of detailed balance of collisions away from equilibrium. They are stronger in the BEC than in the normal gas, and can be more robust against finite temperature smearing than the usual equilibrium Fermi surfaces of Fermi gases. We also show that they give rise to analogous rich phenomena, such as Friedel oscillations in the density correlations and quantum oscillations in response to applied magnetic fields controlled by their areas, albeit with marked quantitative differences. Our results establish non-equilibrium conditions as a promising alternative pathway to achieve the long-sought-after emergence of Fermi surfaces in bosonic system. We outline strategies to experimentally discover these exotic states in ultra-cold atomic clouds.
Quantum Gases (cond-mat.quant-gas)
Comments are welcome!
Phase Transitions in Mismatched Bayesian Inference for the Ising Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Xinyu Sun, Zhou-Quan Wan, Shao-Kai Jian, Hong Yao
Bayesian inference with a mismatched model can develop an overconfident phase, characterized by posterior agreement without faithful reconstruction of the true state. We study Bayesian inference from noisy bond measurements of an Ising model in its paramagnetic phase, with true inverse temperature $ \beta$ and measurement-noise strength $ \Delta$ , while inference assumes corresponding parameters $ \beta_Q$ and $ \Delta_Q$ . Using replica field theory, we analytically show that the overconfidence phase can occur when inference underestimates the measurement noise ($ \Delta_Q < \Delta$ ) or assumes a lower prior temperature than the true one ($ \beta_Q > \beta$ ). An exact change of variables maps the problem to a correlated random-bond Ising model, where the informative, uninformative, and overconfident phases correspond to ferromagnetic, paramagnetic, and spin-glass phases, respectively. We further perform Monte Carlo simulations of the mapped model in three dimensions and establish a finite overconfident region between the informative and uninformative phases, consistent with our analytical prediction. Finally, we show that the true model parameters can be inferred directly from the measurement records, providing a natural route to calibrating the inference model.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn)
4.3 pages + Supplemental Material, 3 figures
Typicality of entanglement growth and transport fluctuations in quantum symmetric exclusion processes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
We use macroscopic fluctuation theory (MFT) to establish the typicality of charge-transfer statistics and entanglement dynamics in the quantum symmetric exclusion process, a model of stochastically hopping free fermions with diffusive transport and long-range quantum coherence. We show that the leading long-time charge-transfer full counting statistics of individual noise realizations coincide almost surely with those of the classical symmetric exclusion process (SSEP), in equilibrium and following quenches from arbitrary occupation-diagonal product states. Our results apply to transient fluctuations in the thermodynamic limit, extending previous work that has primarily focused on stationary regimes. Our approach compares the noise averages of the charge-transfer generating function and its inverse. The former reduces to SSEP, while the latter maps to an auxiliary Brownian energy process whose MFT saddle-point problem is related to that of SSEP, yielding matching large-deviation exponents. Through free-fermion identities relating entanglement to subsystem-number fluctuations, this establishes the self-averaging of the covariance-matrix eigenvalue distribution and of Rényi and von Neumann entropies. We obtain asymptotically exact predictions for entanglement growth from domain-wall and Néel initial states, in excellent agreement with numerical simulations.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
8 pages, 2 figures, 8 pages Supplemental Material
Proximity-Induced Giant Majorana Spin Response in a UTe$_2$-Metal Film Heterostructure
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Jushin Tei, Makoto Shimizu, Yukio Tanaka, Satoshi Fujimoto, Takeshi Mizushima
We establish an experimentally accessible route to identifying Majorana surface states through their intrinsic Ising spin response, using UTe$ _2$ as a concrete platform. The key is to extend the Majorana correlations into an adjacent metallic film via the superconducting proximity effect, thereby making the otherwise surface-localized response accessible to NMR measurements. Remarkably, disorder further sharpens the Majorana signature: impurity scattering suppresses the conventional $ p$ -wave proximity correlations while preserving the Majorana contribution, yielding a giant Ising-anisotropic enhancement of the NMR relaxation rate. This approach also offers a powerful means to distinguish among candidate pairing symmetries.
Superconductivity (cond-mat.supr-con)
5 pages, 4 figures
Mesons, Confinement, and Complexity: A Krylov Space Perspective on the Long-Range Ising Chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Xuhao Jiang, Jad C. Halimeh, N. S. Srivatsa
We investigate the interplay between confinement and Krylov complexity in the long-range transverse-field Ising chain, where power-law interactions $ \sim 1/r^{\alpha}$ generate an effective confining potential between domain walls without an explicit symmetry-breaking field. Using the time-averaged Krylov state complexity after a quench as a diagnostic, we find that the complexity is strongly suppressed and only weakly system size-dependent at small $ \alpha$ and small transverse field $ h_x$ , where confinement is strongest, and crosses over to rapid growth at larger $ \alpha$ , where it increases with system size. Within the confined regime, the oscillation frequencies of the complexity agree with the meson masses of an effective two-kink model, with the dominant frequency growing linearly with the lightest meson mass and the time-averaged complexity decreasing approximately as its inverse square. We further study operator Krylov complexity at finite temperature using the Wightman inner product. At low temperature, it exhibits bounded oscillations that directly encode the meson spectrum, whereas this structure is progressively washed out as the temperature increases. These results identify Krylov complexity as a spectroscopic probe of interaction-induced confinement and reproduce, in a microscopic lattice model, the hallmarks of Krylov complexity identified in confining field theories.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
5 pages, 4 figures, Supplemental Material
Universal Scaling of Conditional Mutual Information in Classical Stochastic Dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Songlei Wang, Chenguang Liang, Zhi-Cheng Yang
Conditional mutual information (CMI) characterizes dependence between two regions conditioned on an intervening buffer. Its characteristic decay length, the Markov length, has recently been identified as a diverging length scale at mixed-state phase transitions. Here, we investigate CMI dynamics in one-dimensional classical stochastic models and propose a universal scaling form for systems whose Markov length diverges with time. We derive this form in the inactive phase of parity-conserving directed percolation, where domain-wall coarsening generates a growing length scale and a self-similar probability distribution. We introduce a Hankel-based truncation scheme that enables matrix-product-state simulations at long times and over large spatial regions. Using this method, we verify the proposed scaling both in the inactive phase and at the nonequilibrium critical point, where the dynamical critical exponent governs Markov-length growth. More broadly, the same scaling form captures cases in which collective inference sets the diverging Markov length. Despite these distinct mechanisms, the CMI between fixed microscopic regions exhibits a common scaling dimension of two. Finally, we extend this framework to temporal CMI, establishing an analogous relation between the strength of conditional dependence in time domain and its characteristic memory time.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
7+18 pages, 12 figures
The Glass Transition: From Competing Theories to Discriminating Tests
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
The dramatic slowing down of liquids approaching the glass transition remains unresolved, partly because competing theoretical explanations are difficult to discriminate. Indeed, several mature, contrasting frameworks account for the main features of glassy phenomenology, making agreement with familiar observations a weak basis for identifying the microscopic mechanism responsible for the slowdown. Recent numerical advances are changing this situation in two complementary ways. Deep equilibration extends controlled equilibrium studies into regimes previously accessible only by extrapolation, allowing established predictions to be stress-tested over a broader dynamical range. At the same time, new numerical methods increasingly provide direct access to theory-specific quantities such as configurational entropy, static lengths, elastic properties, and local activation barriers. I discuss how these developments constrain thermodynamic, facilitation-based, elastic, and excitation-based descriptions. The emerging picture is not yet a unique theory, but a set of increasingly discriminating tests that can reveal where apparently successful laws cease to be universal and identify the microscopic ingredients that causally control the activation barrier.
Soft Condensed Matter (cond-mat.soft)
Perspective, 2 figures
Appl. Phys. Lett. 129, 160502 (2026)
STEM-Bank-26: An Open Dataset of Analytical Scanning Transmission Electron Microscopy Images and Spectra
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Scanning transmission electron microscopy (STEM) is a versatile, multi-modal method for studying materials at the nanoscale. It integrates multiple signal sources to provide atomic resolution imaging alongside spectroscopy for elemental composition and electronic structure. Despite its utility, few datasets spanning multiple years of data have been published. We introduce STEM-Bank-26, a 929 GB open dataset of 37,921 STEM images that spans 1,095 material samples across 1,499 sessions and includes energy-dispersive spectroscopy (EDS) or electron-energy loss spectroscopy (EELS) data for 65.5% of sessions. We extract microscope control trajectories by comparing metadata between sequential images and provide tools for building similar datasets from archival data. To our knowledge, this is the largest openly available dataset that integrates experimental STEM, EDS and EELS data across a broad distribution of samples and sessions.
Materials Science (cond-mat.mtrl-sci)
A Hybrid Brownian Dynamics-kinetic Monte Carlo Framework for Coupled Magnetic and Rotational Dynamics of Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Siraj Ul Haq, Iago López-Vázquez, Kazuya Okada, Sergiu Ruta, Amira Páez-Rodríguez, Lucía Gutiérrez, Òscar Iglesias, David Serantes, Roy W. Chantrell
Simulating the coupled magnetic and rotational dynamics of suspended magnetic nanoparticles (MNPs) over experimentally relevant timescales remains computationally demanding, particularly under low-frequency alternating magnetic fields. Here, we develop a hybrid Brownian Dynamics–kinetic Monte Carlo (BD–kMC) framework that combines thermally activated magnetic switching with particle rotation while retaining local fluctuations of the magnetic moment. These fluctuations are incorporated through Metropolis Monte Carlo (MC) sampling, allowing the moment to depart from the energy minima and thereby capturing the thermally averaged anisotropy torque that governs particle rotation. To preserve the distinction between local fluctuations and magnetic reversals, a barrier-trapping criterion confines MC trial moves to the current energy well, leaving thermally activated switching to the kMC process. For non-interacting single-domain MNPs, comparison with stochastic Landau–Lifshitz–Gilbert (LLG) simulations demonstrates agreement in the equilibrium torque and stationary easy-axis orientation, including the field-driven transition from predominantly perpendicular to parallel alignment. The resulting BD–kMC framework provides an efficient approach to coupled magnetic and Brownian Dynamics, reducing the computational cost of exploring the long timescales relevant to low-frequency magnetic applications.
Materials Science (cond-mat.mtrl-sci)
14 pages. 12 figues, submitted
A 3D-$Δ$PDF-like measure for hidden anisotropy in disordered materials
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
Helena Barker, Thomas C. Nicholas, Andrew L. Goodwin
We introduce a simple correlation function for quantifying hidden local anisotropy in disordered materials. Developed in analogy with the three-dimensional difference pair distribution function (3D-$ \Delta$ PDF), our approach identifies structural correlations that are lost through averaging over bulk symmetry. The same approach might be applied to models of disordered crystals, amorphous materials, and liquids alike.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)
Coulomb- and exchange-driven redistribution of spectral correlations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Zanya Gonzalez Tellez, Miguel Angel Ocaña Bribiesca
Electronic correlations reorganize not only the energies of individual electronic states but also the collective structure of the spectrum. Here, first-principles density functional theory calculations combined with random-matrix spectral statistics are used to examine this reorganization in gamma-Ce within a static spin-polarized DFT+U+SOC description. We distinguish the effects of the Coulomb interaction U from those of the exchange interaction J by analyzing nearest-neighbor spacings, reduced spacing ratios, band velocities, and band curvatures across the Ce-4f manifold. Increasing U does not produce a monotonic transition between Poisson- and Wigner-Dyson-like statistics; instead, the region of strongest level repulsion migrates across the 4f manifold as the interaction increases. Exchange produces a qualitatively different response. At fixed U, strongly repulsive and strongly clustered spectral regions coexist within the same 4f manifold even while the total spin moment and 4f occupation remain nearly unchanged. The clustering persists after resolving the spectrum into its dominant j = 5/2 and j = 7/2 components and differs strongly between calculations having the same numerical value of U-J. Within the present DFT+U+SOC description, the spectral response therefore depends on the separate Coulomb and exchange interactions and cannot be represented completely by a single effective U-J parameter. These results show that energy- and character-resolved spectral statistics expose correlation-driven electronic reorganization that is hidden by conventional integrated observables.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
22 pages and 7 figures
Ensemble-dependent condensate statistics and correlations in an ideal Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
Szymon Augustynowicz, Jan Okoński, Maciej B. Kruk, Ilja Zebergs, Jan Joachim Arlt, Kazimierz Rzążewski, Krzysztof Pawłowski
The choice of statistical ensemble has a measurable impact on the statistical description of Bose-Einstein condensates beyond the well-known grand canonical anomaly. We develop a segmented-contour approach for the ideal Bose gas, which refines the saddle-point approximation by including non-Gaussian corrections in the canonical and microcanonical ensembles. The method applies to a broad class of noninteracting spectra, and provides efficient access to condensate fluctuations, higher moments, and correlation functions.
For a three-dimensional harmonic trap with fixed anisotropy, we find that the ratio of the maxima of the microcanonical and canonical condensate-number variances approaches the theoretically predicted asymptotic value $ 1-3\zeta(3)^2/[4\zeta(2)\zeta(4)]\approx 0.391$ only extremely slowly with increasing particle number. We also show that ensemble effects are visible in the second-order correlation function $ g^{(2)}(x)$ near the condensation crossover. After ballistic release from a three-dimensional harmonic trap, the time evolution of $ g^{(2)}(x)$ preserves the differences between statistical ensembles.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
16 pages, 10 figures
Determination of the Magnetic Penetration Depth from Finite-Element Susceptibility Calculations of Spheroidal and Cylindrical Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Morgan Grant, Antony Carrington
The magnetic penetration depth, $ \lambda$ , is a fundamental parameter of the superconducting state and is commonly determined from precision measurements of the magnetic susceptibility, $ \chi$ , in the Meissner state. However, extracting $ \lambda$ from such measurements requires an accurate treatment of geometry-dependent demagnetization effects, for which analytic results are only available in a limited number of cases. Here we present a finite-element analysis of the magnetic response of three dimensional superconducting spheroids and cylinders with finite penetration depth. By calculating the magnetic moment and susceptibility, $ \chi(\lambda)$ , over a wide range of aspect ratios, we quantify the shape-dependent Meissner response and extract effective demagnetization factors in the $ \lambda \rightarrow 0$ limit. For small but finite $ \lambda$ , we further determine effective sample dimensions from the initial variation of $ \chi(\lambda)$ and propose an improved analytical expression for these. Our results provide a high-precision procedure for determining $ \lambda$ from volume-exclusion based susceptibility measurements and should be directly applicable to the characterization of novel superconducting materials.
Superconductivity (cond-mat.supr-con)
Physical Review B 114.19 (2026): 194507
Physical structure as an organizing principle for universal Hamiltonian learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Mingkang Liu, Zhanghao Zhouyin, Guanghui Wang, Daye Zheng, Lei Shen, Qiangqiang Gu
Density functional theory (DFT) gives the electronic structure of materials, but its cost limits large-supercell calculations and materials screening. Machine-learned Hamiltonians bypass the self-consistent cycle but are usually system-specific; universal ones could cover new compositions and disordered solids. Such models must generalize across chemistry and keep downstream properties physical, while staying inexpensive for large cells. Here we introduce UniTB, a universal E(3) equivariant Hamiltonian representation framework that integrates physical priors rooted in density-functional tight-binding theory with deep learning. UniTB’s network, which corrects a prior Hamiltonian, generalizes across chemistry through a mixture of experts routed by that prior and a charge-equilibration head as in self-consistent-charge tight binding. A projection bounds band shifts from the prior, suppressing spurious states and keeping downstream properties physical. We provide the fastest SO(2) tensor-product GPU kernels for the network. The variant UniTB-Flash assembles its prior from two-center tables at $ O(N)$ cost for $ N$ atoms, against $ O(N\log N)$ on a grid. Trained on 29,242 crystals, UniTB reaches a 0.48 meV matrix-element error on nonmagnetic test crystals spanning 68 elements. Without amorphous training data, both models agree with DFT optics and conductivity of amorphous Ge-Sb-Te. UniTB-Flash ranks candidates with no significant difference from UniTB, whose property values are more accurate; together they screen 16,195 crystals for five application domains of industrial relevance.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
26 pages, 8 figures, 1 table; Supplementary Information (51 pages) included
Anisotropic Structural and Magnetic Response in Sm$_2$Ir$8$Al${31}$: Al-Sublattice Reconstruction upon Sm Substitution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Chemical pressure plays a critical role in determining the crystal structures and physical properties of intermetallic compounds. Here, we report the synthesis, crystal structure, and physical properties of Sm$ _2$ Ir$ _8$ Al$ _{31}$ , a structural analog of UIr$ _4$ Al$ _{15}$ , in which the smaller 5f uranium atoms are replaced by larger 4f samarium atoms. Single-crystal X-ray diffraction reveals a tetragonal $ \sqrt{2}\times\sqrt{2}\times1$ superstructure with space group $ P\bar{4}2_1m$ , derived from a UIr$ _4$ Al$ _{15}$ -like average structure with space group $ P4_2/nmc$ . Comparison with UIr$ _4$ Al$ _{15}$ shows that chemical pressure from U-to-Sm substitution produces a strongly anisotropic structural response rather than a uniform expansion of the Ir-Al framework. While one Ir coordination environment undergoes only modest changes, the other exhibits substantial local rearrangement. The Al sublattice primarily accommodates these structural distortions, with selected Al sites showing positional splitting, anisotropic atomic displacement ellipsoids, and partial occupancies, resulting in an Al-rich composition of approximately Sm$ _2$ Ir$ _8$ Al$ _{31}$ . Magnetic susceptibility measurements reveal a direction dependence, including a broad anomaly near 50 K for selected magnetic-field orientations. However, the absence of corresponding anomalies in heat capacity, electrical resistivity, and lattice parameters suggests that this feature is more consistent with an anisotropic magnetic crossover than a bulk thermodynamic phase transition. These results highlight how chemical substitution at the f-element site can induce Al-sublattice reconstruction and modify the magnetic response within a closely related Ir-Al structural framework.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 4+2figures
Learning the Chronology of Materials Discovery for Synthesizability Prediction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
High-throughput computational and generative approaches are proposing candidate materials far faster than they can be synthesized, making it increasingly important to identify which hypothetical materials are likely to be experimentally realizable. Positive-unlabeled (PU) learning has emerged as a representative framework for synthesizability prediction, yet existing approaches treat experimentally reported materials as a static collection, overlooking the historical trajectory of materials discovery and the diverse practical factors that have driven its progress. Here we introduce ChronoSyn, a chronology-aware machine learning model that jointly learns synthesizability and the relative reporting order of known materials through a shared composition representation. Incorporating discovery chronology provides additional supervision beyond conventional synthesizability labels, improving prediction performance and enabling ChronoSyn to identify experimentally realizable compositions more effectively than baseline models. Applied to approximately 50 million hypothetical compositions, ChronoSyn identifies chemically coherent high-scoring families that include experimentally reported compositions unseen during training. These results highlight the chronology of materials discovery as an informative learning signal and suggest that the path along which known materials were discovered can point the way to those that will be discovered in the future.
Materials Science (cond-mat.mtrl-sci)
47 pages, 7 main figures
Confinement, registry and spin in chromium migration between graphene layers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Mingguang Chen (1), Senfu Zhang (2) ((1) DeepGrounding, (2) Key Laboratory of Magnetism and Magnetic Functional Materials, Ministry of Education, Lanzhou University, Lanzhou 730000, China)
We compare the migration of a single Cr atom on monolayer graphene, between AB-stacked layers and between AA-stacked layers, with one first-principles protocol (PBE+D3(BJ), one cell family, registry anchors and spin-state search). We find three main results. First, on the surface and in the AB gallery Cr stays magnetic and moves almost freely. On the surface the C-C bridge is the minimum in 4x4 and 5x5 cells, and the highest point we sample on a hop lies 10 meV above it (5x5). In the AB gallery Cr sits on the inversion centres of the bilayer, which form a kagome net, and hops between them over 15 meV with a moment of about 4.32 $ \mu_B$ . Second, in the AA gallery the minimum is a nonmagnetic $ \eta^6$ -$ \eta^6$ sandwich that pulls the layers together. Leaving it requires opening the gallery and switching Cr to a moment of 4-5 $ \mu_B$ , so we map the path with separately relaxed spin branches. The barrier estimate is 636 meV in a 3x3 cell but 260 and 185 meV in 5x5 cells with the far-field spacing pinned and free, and it is not yet converged. At 300 K, with equal prefactors and if the spin change is not rate-limiting, Cr hops between AA layers 3-4 orders of magnitude more slowly than between AB layers, using the 5x5 AA estimates and the 3x3 AB band. These AA numbers are specific to PBE+D3: an on-site U of 1.0 eV on Cr d already makes the magnetic states the AA ground state. Third, Cr binds 246-666 meV more strongly in AA than in AB registry, so the fast AB hop requires that the layers keep their Bernal registry around Cr.
Materials Science (cond-mat.mtrl-sci)
10 pages, 3 figures, 6 tables. Ancillary files (DA2_data): run records, trajectories and the scripts that regenerate every number, table and figure
Three-dimensional quantum Hall insulators in magnetic pyrochlore systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Ze-Xun Lin, Robert-Jan Slager, Claudio Castelnovo
We show that a class of pyrochlore materials provides a route to realize 3D Quantum Hall insulators, based on magnetic texture and flat band interference. We study itinerant electrons on a pyrochlore lattice Kondo-coupled to localized moments living on another interpenetrating pyrochlore lattice, with the moments forming a field-selected three-in/one-out texture. The noncoplanar texture generates complex spin-dependent hopping amplitudes and unequal local exchange energies, reconstructing the compact-localized parent flat bands into narrow bands separated by a global three-dimensional gap. The low-energy states are concentrated predominantly on kagome planes within the three-dimensional lattice, reflecting the combined effects of quantum interference and the texture-induced sublattice potential. When the lowest band is fully occupied, the response is characterized by a Chern triplet $ \mathbf{C}=(1,1,1)$ and reciprocal Hall vector $ \mathbf{G}{\mathrm{H}}=(2\pi/a)(1,1,1)$ , giving $ \sigma{yz}=\sigma_{zx}=\sigma_{xy}=e^2/(ha)$ . The quantized bulk Hall response enforces chiral surface spectral flow, visible as noncontractible Fermi loops at the surface. Our work opens a new direction in the search for three-dimensional quantum Hall physics in magnetic pyrochlore systems, and suggests a broad design principle based on the interplay of magnetic texture and flat-band interference.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Spin Rectification in Series and Parallel Networks of Ferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Md. Majibul Haque Babu, Maxim Tsoi
We present the experimental study of spin rectification in parallel and series networks of ferromagnetic conductors. The networks were composed of Ni36Fe64 elements (wires) which, when subject to ferromagnetic resonance (FMR), develop a small spin-rectification photovoltage. We found that the effect of spin rectification can be modeled as an increase in resistance of the ferromagnetic elements and closely follows the usual dependence of total network resistance in series and parallel electric circuits: the total spin-rectification photovoltage in ferromagnetic wires connected in series is equal to the algebraic sum of contributions from individual wires, while in the parallel connection one needs to add the reciprocals of the individual contributions. Our results support a simple way to control and manipulate the magnitude of spin-rectification photovoltage in multi-element spintronic devices.
Materials Science (cond-mat.mtrl-sci)
A cascade of orbital-field-driven phases with a Lifshitz-type transition to unidirectional spiral order
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Frustration in magnetic systems gives rise to unconventional orders and exotic spin liquids. Here, we explore a new type of frustration arising from an intrinsic bond-dependent orbital-field that couples orbital degrees of freedom to spin correlations. Introducing this orbital-field interaction into the antiferromagnetic Heisenberg model on the honeycomb lattice, we show that local spin-orbital constraints generate a subextensive degeneracy, lifted by order-by-disorder to select distinct collinear magnets in a cascade of phases as the orbital field increases from a para-orbital liquid. At larger fields, the selected phase gives way to an incommensurate unidirectional spiral that spontaneously breaks chiral symmetry. This transition is driven by the coupling of a Goldstone mode to gapped dynamical spin-orbital fluctuations. The spin stiffness becomes negative along a particular direction, while the spiral wavevector grows as the square root of the distance from the transition, signaling a Lifshitz-type transition. We present a microscopic route to realizing this orbital field and discuss candidate materials.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 6 figures, and Supplemental Materials (17 pages, 5 figures)
Exciton-driven coherent dressing in transient absorption
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Jinyuan Wu, Chang Shu, Yang-hao Chan, Diana Y. Qiu
While coherent excitons have recently been observed to dress electronic states in time- and angle-resolved photoemission spectroscopy (tr-ARPES), exciton-driven dressing in optical spectroscopy remains largely unexplored. This work develops a theoretical and computational approach to exciton-driven dressing effects in transient absorption spectroscopy in the time-dependent adiabatic GW formalism and derives two symmetry- and band topology-protected selections rules for exciton-dressed transient absorption, unique from tr-ARPES. We then numerically calculate exciton-dressed transient absorption spectra of monolayer MoS2 and demonstrate the selection rules and their lifting after symmetry breaking.
Materials Science (cond-mat.mtrl-sci)
Towards Quantum Computation of Bulk FeO
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Daniel Staros, Federico Petrovich, Ammar Kirmani, Daniel N. Blaschke, M. Cerezo, Jian-Xin Zhu
Quantum computation offers a promising path towards efficient calculations of the electronic structure of correlated materials. The properties of iron-based materials, which are key for advancing geological and astrophysical understanding, are notoriously difficult to calculate with classical computers. However, despite the many recent advances in quantum computing on near intermediate scale quantum hardware, a full treatment of the electronic structure of high-$ Z$ atoms or molecules remains challenging. Here, we investigate the ground-state properties of molecular FeO and Fe$ _2$ O$ _2$ model Hamiltonians using classical exact diagonalization, Variational Quantum Eigensolver (VQE), and Sample-based Quantum Diagonalization (SQD). The experimental quintet ground state of FeO is recovered classically and with quantum algorithms, while a nonet ground state is recovered for Fe$ _2$ O$ _2$ . Although raw VQE does not achieve chemical accuracy for the ground state of FeO or Fe$ _2$ O$ _2$ , SQD with two connectivity shells recovers the exact ground energy for both molecules utilizing remarkably few quantum computational resources. Overall, our results indicate that $ ab ; initio$ -informed low-energy models of correlated materials, combined with SQD, offer a new alternative for scaling up calculations of ground-state properties of strongly correlated solids on existing quantum hardware.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
13 pages, 3 figures
Multiwavelength Photoluminescence as a Non-destructive Probe of Depth-Dependent UV Damage in Perovskite Semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Zixu Huang, Julisa Juarez, Akash Dasgupta, David S. Ginger
Buried interfaces play a critical role in the operational stability of perovskite optoelectronic devices, yet remain challenging to probe non-destructively. Here, we demonstrate a multiwavelength photoluminescence-based approach exploiting the wavelength-dependent absorption of perovskites, enabling fast, and non-destructive probing of depth-sensitive degradation behavior of perovskite devices under operational conditions. Using ultraviolet (UV) light-soaking with different indium tin oxide (ITO) modifiers as a test case, we employ wide-field photoluminescence (PL) imaging, time-resolved photoluminescence (trPL) and ideality factor measurements with different wavelength excitation to characterize degradation behavior of both perovskite thin films and photovoltaic devices under UV soaking. Using only nondestructive characterization, we show that UV-induced degradation in p-i-n perovskite solar cells occurs preferentially at the HTL interface, adversely affecting device stability, consistent with ex-situ destructive tests. Our results also show that modifying the buried interface with 3-mercaptopropyltrimethoxysilane reduces UV-induced damage at the buried interface, thus improving the UV stability of both perovskite films and devices. This work establishes a fast, non-destructive strategy to screen depth-dependent degradation in perovskite devices, offering insights for interface design and stability optimization.
Materials Science (cond-mat.mtrl-sci)
Oxygen partial pressure induced dielectric phase evolution in PLD deposited Barium Strontium Titanate thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Shashi Pandey, Suk Hyun Sung, Jacob Fernandez, John T. Heron
Barium Strontium Titanate ((BaxSr1-x)TiO3, BST) thin films are amongst the most extensively studied dielectric alloys over the last decade. This is due to the tunability of the dielectric constant and dissipation factor in the underlying ferroelectric and paraelectric states. One important feature of BST is that the competition between the ferroelectric BaTiO3 and the paraelectric SrTiO3 parent phases can be tuned by the A-site alloy concentration, opening a platform for exploring dielectric phase competition. However, the understanding of the interplay between and establishing the control of the dielectric phase from thin film deposition parameters has not been sufficiently reported in the literature. Here, we synthesized a series of SrRuO3/BST/SrRuO3 epitaxial thin film heterostructures by Pulsed Laser Deposition (PLD) from a (Ba0.9Sr0.1)TiO3 target under systematic variation of the oxygen partial pressure during the BST deposition. We mapped the dielectric phase of the film to the oxygen growth pressure, film composition, and film crystal structure. A ferroelectric, relaxor-like, or paraelectric phase can be obtained with relatively moderate change in oxygen growth pressure. Scanning transmission electron microscopy (STEM) analysis further indicates that this pressure-dependent phase evolution is accompanied by a structural transition of the BST lattice from tetragonal toward a nearly cubic phase, with the latter corresponding to the relaxor-like state. The control of the dielectric phase opens a pathway to study phase evolution and enable future computing technologies.
Materials Science (cond-mat.mtrl-sci)
Ratchet Effects for Swarmalators on Asymmetric Substrates
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
B. Albert, A. Libal, C.J.O. Reichhardt, C. Reichhardt
Swarmalators are particles which have internal degrees of freedom in the form of phase oscillators that can synchronize and change the dynamics of the particles. We explore the active matter disk swarmalator model proposed by Adorjáni [Phys. Rev. E 109, 024607 (2024)] where there is an additional attraction or repulsion determined by whether the phases of particles within a certain radius synchronize or anti-synchronize. This model in the absence of swarmalator rules forms a motility-induced phase-separated (MIPS) state at high activity, but when the swarmalator rules are present, a number of additional states appear including an active gel, labyrinth state, frustrated MIPS, and frustrated fluid states. Here we examine ratchet effects for the Adorjáni model coupled to asymmetric substrates. We find that swarmalator interactions can strongly enhance or suppress active matter ratcheting depending on the structural state of the system, and show that the ratchet efficiency depends on the substrate strength, substrate lattice spacing, and the motor force on the particles. The gel state exhibits the weakest ratcheting for small substrate spacing and can even produce a reversed ratchet motion, but shows the strongest ratcheting for large motor forces. The labyrinth state exhibits the strongest ratcheting over a wide range of parameters since the quasi-one-dimensional labyrinth morphology can match the substrate geometry well.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
13 pages, 17 figures
No friction required: Self-locking in entangled assemblies of curved filaments
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Benjamin R. Greenvall, Jay van den Berg, Ross E. Meinhart, Patrick A. Staudenmayer, Alfred J. Crosby, Gregory M. Grason
Filaments are incredible material building blocks that, when entangled together, form robust structures with remarkable adaptive mechanics, from stiff cables to stretchable knits. Basic questions about the mechanism that holds together such structures, especially assemblies like rope, without attractive physical or chemical bonds between constituents are among the oldest considered in materials science. Contradicting a long-standing picture that structural integrity of rope-like assemblies rely on a combination of external loading and inter-filament friction to prevent spontaneous detangling (e.g. fraying of a cut rope), we demonstrate that assemblies of intrinsically-curved filaments can achieve structural integrity purely from the competition of elastic forces that resist shape-change and (traction-free) repulsive forces that prevent overlap. We analyze a friction-free model of assembly of intrinsically-helical filaments, and show that depending on filament number and preferred filament shape, overcrowding in the assemblies generate elastic pre-stresses that give rise to either self-locking entanglement or spontaneous detanglement through propagation of a soliton-like detanglement front through assemblies. We test a generalized fracture criterion for spontaneous detangling and confirm the role of shape-elastic costs to self-locking via experiment and simulation of frictional filaments, demonstrating a range of bundled structures which cannot be made self-locking for any value of friction. The mechanism of ``purely elastic cohesion” illuminated here sheds light on self-locking in a broader class of entangled structures, and further, offers design principles for new classes of active filament materials capable of stimuli-responsive assembly and disassembly.
Soft Condensed Matter (cond-mat.soft)
14 pages, 5 figures, 4 supplemental videos, 1 supplemental appendix (15 pages)
Large superconducting diode effect indicates nonuniform triplet pairing in UTe2
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Zheyu Wu, Daniel Shaffer, Dmitry V. Chichinadze, Mengmeng Long, Hanyi Chen, Andrej Cabala, Theodore I. Weinberger, Maurice Bal, Steffen Wiedmann, Dave Graf, Vladimir Sechovský, Michal Vališka, F. Malte Grosche, Alex Levchenko, Alexander G. Eaton
The superconducting diode effect (SDE) is characterized by unequal critical current magnitudes for opposite-polarity current flow, owing to broken spatial-inversion and time-reversal symmetries. For a superconducting pair wavefunction to spontaneously break inversion symmetry implies the formation of Cooper pairs with nonzero momentum, yielding a nonuniform superconducting state. For singlet superconductors, the formation of such a (FFLO) state has long been understood to provide an escape from high field Pauli pair-breaking – how and why such an effect might occur for equal spin pairing is an open question. Here we report the observation of a large SDE in bulk specimens of the three-dimensional heavy-fermion triplet superconductor UTe$ _2$ , with a peak diode efficiency of 33% at the high magnetic field strength of 33.6 T, representing the highest-field observation of the SDE to date. Crucially, this nonreciprocal transport is strictly confined to a narrow field regime where superconductivity coexists with a field-induced spin-polarized state near a first-order metamagnetic phase boundary. The absence of the SDE away from this slender phase-intersection argues strongly against purely extrinsic vortex pinning asymmetries. Instead, our findings indicate spontaneous inversion symmetry breaking accompanied by finite-momentum Cooper pairing. We model this behavior using a phenomenological Ginzburg-Landau theory, demonstrating that the intertwining of magnetic and triplet superconducting orders can stabilize an odd-parity FFLO state.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Vortex anisotropy in chiral and nematic superconductors with strain
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
David Shuliutsky, Moshe Goldstein
Unconventional superconductors with a two-component order parameter support the existence of a rotational symmetry breaking nematic phase and a time-reversal symmetry breaking chiral phase. A recent experiment on 4Hb-TaS$ 2$ surprisingly shows both twofold anisotropy in $ H{c2}$ , which suggests nematic superconductivity, as well as isotropic vortices at low temperatures, which suggest chiral superconductivity. To resolve this apparent conundrum we write down the appropriate Ginzburg-Landau equations and develop a numerically efficient algorithm for finding vortex solutions, allowing us to study their shape and anisotropy over a broad parameter range. We also demonstrate analytically that, to leading order, the vortex anisotropy is independent of strain in the nematic case, but is linearly dependent on it in the chiral phase, providing a possible way to distinguish the two phases. Using all these results we show that, in the presence of strain, in a large parameter regime the system behaves nematically near the transition, leading to an anisotropy of $ H_{c2}$ , but is dominantly chiral away from the transition, leading to parametrically smaller vortex anisotropy, in line with the experiment.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 7 figures
Spin Relaxation and Electrical Control of Spin Transport in Few-Layer $T_{\rm d}$-MoTe$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
T. Wakamura, M. Hashisaka, M. Bard, S. Okazaki, T. Sasagawa, T. Taniguchi, K. Watanabe, K. Muraki, N. Kumada
We report electrical tuning of spin relaxation in atomically thin $ T_{\rm d}$ -MoTe$ 2$ , a representative low-symmetry transition metal dichalcogenide. Weak antilocalization measurements reveal strong spin–orbit interaction with spin–orbit lengths of tens of nanometers, consistent with recent theoretical predictions. Despite the semimetallic nature of $ T{\rm d}$ -MoTe$ 2$ , in the ultrathin limit the spin–orbit scattering time can be tuned electrostatically by up to threefold. We further investigate vertical electric field effects on the spin–orbit length and time, and demonstrate the modulation of the Rashba parameters. Relation between spin–orbit scattering time and the diffusion coefficient indicates that spin relaxation is governed by the D’yakonov–Perel’ mechanism in both monolayer and bilayer $ T{\rm d}$ -MoTe$ 2$ . These results establish few-layer $ T{\rm d}$ -MoTe$ _2$ as a platform for electrically tunable spin transport, thereby providing insight into spin relaxation in low-symmetry transition metal dichalcogenides.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
11 pages, 8 figures, 2 tables
p-Adic statistical field theory of fluctuation effects in hierarchical neural networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
The Buice-Cowan field theory [PRE 75, 051919 (2007)] describes fluctuations and correlations of neural activity through a path integral whose mean-field limit is the Wilson-Cowan equation and whose critical behavior belongs to the directed percolation class. In its continuum limit the neurons are the points of a Euclidean space and activity spreads by ordinary diffusion, which encodes neither the hierarchical organization of cortical networks nor their small-world property. We formulate a version of the theory in which the neurons are organized in an infinite, self-similar, tree-like structure, described by the p-adic numbers. The path integral carries over unchanged, and finite networks are exact restrictions of the continuum theory. The main change is in the linear response: in the Euclidean theory every short-range kernel reduces to the Laplacian, while in the p-adic theory each connectivity kernel gives its own nonlocal p-adic diffusion operator. For couplings that decay by a fixed factor per level of the hierarchy this is the Taibleson-Vladimirov operator, and the critical theory is an ultrametric Reggeon field theory whose upper critical dimension is twice the decay exponent of the coupling. Hence the decay of the coupling up the hierarchy, and not the dimension of space, decides whether mean-field exponents apply. We obtain a Ginzburg-type criterion, loop-corrected hierarchical Wilson-Cowan equations, log-periodic corrections to scaling and power-law correlations. Exact simulations on a tree support the predictions: the avalanche-size exponent takes the mean-field value 3/2 when the coupling decays slowly and decreases toward the directed-percolation value when it decays fast. The hierarchical network is also small-world when the decay exponent is smaller than the dimension, a property that the Euclidean theory obtains only by assuming long-range coupling.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph), Neurons and Cognition (q-bio.NC)
Hierarchical connectivity sets the upper critical dimension of neural avalanches
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
Neural avalanches with size exponent $ 3/2$ are usually explained by mean-field critical branching, which for short-range coupling requires dimension $ N\ge4$ . We show that hierarchical connectivity removes this constraint. In a $ p$ -adic version of the Buice–Cowan field theory, a coupling that decays by $ p^{-(N+\sigma)}$ per hierarchical level selects the Taibleson–Vladimirov operator, and the critical theory is ultrametric directed percolation with upper critical dimension $ N_c=2\sigma$ . Exact simulations on a tree give $ \tau_S=3/2$ for $ \sigma\le N/2$ , decreasing continuously for $ \sigma>N/2$ .
Disordered Systems and Neural Networks (cond-mat.dis-nn), Neurons and Cognition (q-bio.NC)
Rotational Perturbation Theory for Magnetic Interactions
New Submission | Other Condensed Matter (cond-mat.other) | 2026-10-28 20:00 EDT
We develop rotational perturbation theory for magnetic interactions in collinear and noncollinear systems, distinguishing prescribed rotations of exchange fields from constrained rotations of magnetic moments. At the full exchange splitting, we derive Green-function expressions for prescribedfield energy curvatures directly from perturbation theory, without invoking the local force theorem; constrained-moment curvatures additionally require the stationary magnetic response and are related to the inverse static susceptibility. We examine noncollinear pair interactions and planar and conical spin spirals, and derive the long-wavelength ferromagnetic spin-wave stiffness and, assuming adiabatic sublattice precession, the antiferromagnetic spin-wave velocity. Orbital-nonlocal magnetic potentials and correlated electronic response reveal further requirements for connecting rotational curvatures to collective magnetic behavior. As a practical extension, we project the complete transverse pair Hessian onto an effective scalar Heisenberg exchange and quantify the unreconstructed curvature. Biquadratic and three-spin examples illustrate why locally extracted exchange coefficients need not represent transferable bilinear interactions.
Other Condensed Matter (cond-mat.other)
Beyond Geometry: Hole-Edge Atomic Configuration as a Design Variable in Graphyne Kirigami
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Guilherme B. Kanegae, Alexandre F. Fonseca
Kirigami-inspired cuts are an established route to stretchability in two-dimensional materials. At the nanoscale, however, cut edges are not purely geometric: they comprise discrete atomic configurations that can alter the mechanical response. In graphene, a given cut geometry fixes the edge structure; graphyne, a porous carbon allotrope with an intrinsic band gap, lifts this constraint, as identical cut geometries can yield distinct hole-edge configurations. Using molecular dynamics simulations, we report the first atomistic study of $ \gamma$ -graphyne kirigami (GYK), and compared with graphene kirigami. GYK reaches yield strains up to 9.6 times that of pristine $ \gamma$ -graphyne, with a response governed by both cut geometry and local hole-edge structure. Removing just two carbon atoms at selected edge sites further raises the yield strain by up to 35%, with little loss of yield stress. These findings identify hole-edge atomic configuration as an additional design parameter, expanding the design space for nanoscale kirigami engineering.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 figures, 1 table, Sup. Info appended
Nano-Nb Superconducting 3D Josephson Junctions Arrays in Cu-Normal Matrix: Superconducting Phase Coherence and Quantum Fluctuations Properties
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
R. L. de Almeida, J. Albino Aguiar, J. A. H. Coaquira
To address the complex interplay of microstructural evolution, phase separation, superconductivity coherence and quantum fluctuations, we prepared Cuxwt%Nb series of granular samples by rapidly cooling, where the niobium concentration varied (x = 3, 5, 15, 20). By employing this method, we successfully obtained samples characterized by well-defined precipitates of niobium, featuring regular sizes and grain spacing. The goal was to establish a systematic and robust method approach for obtaining samples with different of sub-micrometric precipitates distributions but also to investigate their superconducting properties. Structural characterization by optical and Scanning Electron Microscopy, dc Mdc[H,T] ac inductive , as well the magneto-transport measures rhodc[H,T], Rdc[V,I.H,T], I[V,H,T] and [H,T,I] were done. Also, using a micro Hall sensor with 10 measuring transverse voltage bridges regularly distributed, we were able to obtain the real external applied magnetic field value inside of the chamber sample space. Thus e studied the dependence of configuration of the Nb grains in the superconducting coupling order parameter properties that connects the grains superconductors to the normal Cu matrix. We verify through magnetization and transport measures the signature of the double transition. This, when we apply current of different intensities, in the transport measures, and different field values, in the inductive measures. This behavior is an indication that our system is made up of by a collection of superconducting grains immersed in a well-organized in a non-superconducting matrix. The results indicate that the superconducting properties of these systems are manifested usually through two transition temperatures Tc(H) e TcJ(H).
Superconductivity (cond-mat.supr-con)
Preprint; 3D Josephson junction arrays; granular superconductivity; Cu-Nb alloys, 26 figures
Learning Multiscale Dynamics of Nanoparticle Self-Assembly
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Shuaifeng Li, Puquan Pan, Jonas Hallstrom, Nicholas Kotov, Paul Bogdan, Qian Chen, Xiaoming Mao
Nanoparticle self-assembly offers a powerful route to programmable functional materials, but its dynamics remain difficult to understand because they arise from multiscale, many-body, and environment-dependent interactions. Liquid-phase transmission electron microscopy (LPTEM) enables real-time observation of these dynamics, yet extracting the underlying physical laws from highly stochastic trajectories remains a significant challenge. Here we develop a physics-informed, time-varying autoregressive framework that learns multiscale self-assembly dynamics directly from LPTEM videos. Continuous Eulerian fields with local density and orientational order are coarse-grained from individual video frames and evolved by a sparse, nearest-neighbor operator optimized over a constrained matrix manifold. This interpretable approach captures long-time large scale phase transitions by tracking operator volatility over time, and short-timescale local evolution and transport rules. Crucially, we extract the underlying partial differential equations, where expected symmetries naturally emerge, enabling the direct inference of fundamental coefficients. Our framework provides a robust, computationally efficient tool for discovering hidden physical mechanisms from observational data, opening a path toward the predictive design of self-assembled nanostructures.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Spin-Charge Conversion in an Epitaxial Kagome Flat-Band Metal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Wenyi Zhou, Yuqing Zhu, Katherine Johnson, Hari Paudyal, Duy Nguyen, Dimitri King, Jaden Ma, Jay A. Gupta, Michael E. Flatte, Roland K. Kawakami
The formation of topological flat bands near the Fermi level in kagome-structured metals has generated substantial research interest. One key consequence of this electronic structure is the strong anisotropy in charge transport, such as the significantly higher in-plane resistivity relative to the out-of-plane direction. However, the spin transport properties of these flat-band kagome metals are still largely unexplored. In this work, we investigate spin-charge conversion in CoSn, a representative flat-band kagome metal. Scanning tunneling microscopy is employed to image the CoSn surface with atomic resolution, and $ dI/dV$ spectroscopy shows clear signatures of the flat bands. Using magneto-optical techniques, we quantify the spin-orbit torque (SOT) in bilayers of ferromagnetic nickel (Ni) and c-plane CoSn thin films. We find a large effective spin Hall angle of $ \theta_{SH} = 0.484 \pm 0.005$ within the CoSn layers, significantly exceeding the value measured for Pt of $ \theta_{SH} = 0.0436 \pm 0.0003$ in Ni/Pt bilayers. Density functional theory (DFT) calculations provide a microscopic understanding of the intrinsic spin Hall effect in CoSn, elucidating the sources of Berry curvature in momentum space. These findings establish kagome metals as promising materials for efficient spin-charge conversion and low-power spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures
Constructive Cavity Method for Ising Restricted and Deep Boltzmann Machines with Gaussian Couplings
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Simone Franchini, Francesco Concetti, Giampiero Bardella, Liming Pan
We apply the Constructive Cavity Method (CCM) to the dense, Ising type, restricted and deep Boltzmann machine with Gaussian couplings between adjacent layers. After identifying the core and interface contributions, CCM identifies the blanket decomposition of the cavity variables with the Aizenman–Sims–Starr random overlap structure. We apply the Random Energy Model (REM) universality ansatz to represent the cavity free energies by those of a generalized random energy model (GREM) and evaluate them recursively through Poisson point processes (PPPs). In the layer-wise gauge each layer is cut with its own cumulative fraction $ |U_\ell\cap L_p|=\lambda_p q_\ell^{(p)}N+o(N)$ , with $ \mathbf 0=\mathbf q_0\le\mathbf q_1\le\cdots\le\mathbf q_r=\mathbf 1$ , where $ \mathbf q_\ell=(q_\ell^{(1)},\ldots,q_\ell^{(K)})$ . Here $ U_\ell$ is the cumulative blanket union up to blanket $ \ell$ . The index $ p$ labels architectural layers, whereas $ \ell$ labels the blankets. The dependence on the multilayer geometry is carried by the two matrices $ M=2M_0\Lambda$ and $ M_1=\Lambda M_0\Lambda$ . The constructive cavity field in layer $ p$ has blanket variances $ Q_\ell^{(p)}-Q_{\ell-1}^{(p)}=(M(\mathbf q_\ell-\mathbf q_{\ell-1}))p$ , while the correction field has blanket variances $ Q\ell-Q_{\ell-1}=\mathbf q_\ell^\top M_1\mathbf q_\ell-\mathbf q_{\ell-1}^\top M_1\mathbf q_{\ell-1}$ . The nested REM–PPP average gives the finite-level constructive cavity functional $ \mathcal{P}{\mathrm{RBM/DBM}}^{\mathrm{CCM}}(\zeta,\mathbf q)=\log2+\sum{p=1}^K\lambda_pX_0^{(p)}-\frac12\sum_{\ell=0}^{r-1}\zeta_\ell(\mathbf q_{\ell+1}^\top M_1\mathbf q_{\ell+1}-\mathbf q_\ell^\top M_1\mathbf q_\ell)$ . The balanced scalar gauge is recovered by imposing $ \mathbf q_\ell=q_\ell\mathbf 1$ . Selecting the physical value in the non-convex multilayer regime is a separate problem.
Statistical Mechanics (cond-mat.stat-mech)
29 pages, 1 figure
Measurement-induced entanglement phases in hyperbolic gauge-Higgs models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Cole Kelson-Packer, Hiroki Sukeno, Akimasa Miyake
Gauge-Higgs theory in flat spacetime provides a prime theoretical model of multiple phases of matter with distinct entanglement structures. More recently, there has been interest in hyperbolic space and the influence its extensive boundaries have on these structures. Entanglement transitions between non-equilibrium phases, such as topological phases, can be realized by the competition of non-commutating measurements. Here we study the entanglement phases of gauge-Higgs models on hyperbolic lattices described by measurement-only dynamics. We chart 2D phase diagrams by employing topological entanglement entropy and introducing a generalized measurement-induced entanglement tailored for hyperbolic Higgs phases. Utilizing duality, we find a phase absent in Euclidean space, wherein the bulk lattice hosts separated clusters of symmetry-protected topological order. Transitions between this “archipelago” phase and neighboring topological and trivial phases feature a critical exponent $ \delta$ belonging to a mean-field universality class. Our essential tool is a 3D resource state inspired by measurement-based quantum computation that simulates the spacetime evolution of the 2D quantum state with a third direction of entanglement. This allows us to analyze spacetime “sponges” of entanglement, which map to classical percolation theory and allow us to infer values of critical points on our phase diagrams’ boundaries.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
12 Figures, 4 Tables + 7 Figures, 1 Table
Laser-Induced 90-Degree Magnetization Switching for Single-Element 2D Sensing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Floris J. F. van Riel, Niels F. L. van Kempen, Bert Koopmans, Diana C. Leitao
Magnetoresistive sensors with multiaxial sensitivity are interesting for field mapping applications where local measurement of multiple magnetic field components is needed. Existing device designs are often discretized with separate sensing elements for each vector component, or they require complex detection schemes to distinguish the different components. In this work, we showcase a single-element two-dimensional vector sensor with on-demand reprogrammable sensing axis using light and optically switchable materials. Our device is an anisotropic magnetoresistive sensor with $ 90^\circ$ togglable sensitivity upon excitation with ultrashort laser pulses. The sensor consists of an optically switchable Co/Gd thin-film bilayer, patterned into a cross shape that stabilizes two orthogonal in-plane magnetization directions. By selectively addressing one diagonal of the cross, a single laser pulses toggle switches the magnetization direction in the center of the cross by $ 90^\circ$ . Moreover, the field sensitivity of the device is toggled between the $ x$ - and $ y$ -axes, which we detected electrically with the planar Hall effect. Our results form a milestone towards optically reprogrammable integrated magnetic vector sensors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
First-principles-based search for emergent topological spin textures in transition-metal dichalcogenide monolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Yuhyun Cha, Do Hoon Kiem, Myung Joon Han
Topological spin textures such as skyrmions and bimerons offer rich physical functionalities and strong potential for future spin-based technologies. Identifying materials that host such emergent magnetic states, however, remains challenging due to the complex interplay between microscopic magnetic interactions and large-scale spin textures. Here, using a multiscale first-principles discovery framework, we identify a broad class of two-dimensional materials that stabilize nontrivial spin textures. The framework integrates relativistic density functional theory, magnetic force theory, and atomistic spin-dynamics simulations, enabling a direct connection between electronic interactions and emergent magnetic textures and allowing efficient screening of systems with large magnetic unit cells and competing exchange interactions. Applying this approach, we systematically screen 312 monolayer transition-metal dichalcogenides across 1T and 2H phases of 3d, 4d, and 5d transition metals. We uncover a diverse set of emergent spin textures, including skyrmions, bimerons, and complex domain states, and clarify their distinct stabilization mechanisms driven by exchange interactions, Dzyaloshinskii-Moriya interactions, and magnetic frustration. These results identify promising candidate materials for topological spin textures and establish a transferable computational framework for accelerating materials discovery of complex magnetic states in two dimensions.
Materials Science (cond-mat.mtrl-sci)
npj Comput. Mater. 12, 292 (2026)
Continuum neural wavefunctions for anyons on a torus
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Ahmed Khalifa, Shubhayu Chatterjee
Mobile anyons in topologically ordered phases provide a setting to investigate how fractional exchange statistics shapes collective behavior at finite density. We introduce AnyFormer: a neural variational framework for continuum anyons on a torus that explicitly incorporates statistical interactions and global winding constraints. We construct a smooth orbital frame that enforces the matrix-valued torus boundary conditions, and supplement it with an analytic pair factor that supplies the regular collision behavior. The orbital geometry and many-body amplitudes are optimized in parallel by variational Monte Carlo. We apply AnyFormer to semions without an external field or interaction potential, isolating unique correlations generated solely by statistics. Our framework closely matches exact two-semion energies and yields lower variational energies than finite-cutoff exact diagonalization for $ N = 4$ and $ 6$ semions. Scaling up to $ N = 16$ semions, well beyond the limits of continuum diagonalization, our calculations reveal states with pronounced correlation holes, suppressed long-wavelength density fluctuations, and a reversal of pair circulation at a distance set by the mean particle spacing. For $ N = 12$ and $ 16$ semions, the circulation develops damped spatial oscillations. AnyFormer thus provides a scalable variational neural-net framework for microscopic studies of correlations, chiral motion, and collective phases of bulk anyonic matter.
Strongly Correlated Electrons (cond-mat.str-el)
25 pages, 7 figures; includes Supplemental Material
Ferron-driven motion of non-collinear ferroelectric domain walls
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Huanhuan Yang, Gerrit E. W. Bauer
We study the propagation of ferrons, the quanta of electric polarization waves, through a ferroelectric texture. We predict by analytic and numerical calculations that a $ 90^\circ$ domain wall (DW) operates as a beam splitter of longitudinal ferron and transverse optical phonon modes. An associated momentum-flux imbalance leads to forces that drive DW motion. In the weak-anisotropy limit, the DW becomes a rotating texture with nearly fixed-modulus, whose low-energy dynamics is described by a sine-Gordon equation. A ferron source then attracts the DW through a damping-induced force. Both driving forces scale linearly with incident wave intensity. Our results uncover qualitatively different routes to driven ferroelectric DW motion enabled by the vector nature of the polarization and offer functionalities for THz ferroelectric devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Comprehensive QM/ML Study of Dislocation Loop Line Segments in α-Zr Part I: Loop Core Geometries, Solute Binding, and Transition Barriers
Loop Core Geometries, Solute Binding, and Transition Barriers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Junting Zhang, Andrew P. Horsfield, Mark R. Wenman
Zr cladding alloys in nuclear reactors are exposed to high neutron fluxes, making irradiation-induced defects and solute segregation central to understanding their in-service behaviour. Dislocation cores involve short-range chemistry and long-range elastic fields, which are difficult to describe simultaneously using conventional atomistic methods. Using a hybrid quantum mechanics/machine learning (QM/ML) framework, this part of work examines prismatic loops in hcp {\alpha}-Zr. All three loop variants are considered, including faulted and perfect, interstitial- and vacancy-type, and first- and second-order prismatic configurations. Nine possible dislocation line segments are characterised in terms of core geometry, solute binding, glide barriers and faulted-to-perfect transition pathways using QM/ML and newly implemented QM/ML-NEB calculations. Shockley and half-Shockley partials, together with basal and prismatic fault ribbons, are found to govern core stabilisation. Fe and H preferentially bind to faulted segments, whereas Sn and Nb favour perfect segments. Solutes can also drive partial motion, recombination and local unfaulting. These results establish a comprehensive picture of loop microstructure, solute trapping and transition mechanisms in {\alpha}-Zr.
Materials Science (cond-mat.mtrl-sci)
main text 33 pages,12 figures
Designing Geared Molecular Rotors in Flexible Metal-Organic Frameworks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Konstantin Stracke, Jack D. Evans
Translating macroscopic mechanical concepts such as gears to the molecular scale offers a route to precise control over nanoscale motion, inspired by the efficiency of biological machines. In this work, we explore two-dimensional interlocked linker rotations in the flexible metal-organic framework NU-2002. The volume-dependent free energy landscape is mapped using bias-deletion metadynamics to identify six characteristic phases, ranging from very closed to very open pore. We then perform unbiased molecular dynamics simulations at each phase to track rotation events and evaluate co-rotation statistics, calculate free energy barriers, and measure pairwise radial force transfer between neighbouring linkers. We show that the free energy barrier acts as a rotational-speed filter, where rare rotational transitions lead to higher speeds on average. Across the volume profile, we classify four distinct geared regimes: sterically restricted rotations at small volumes (Jammed Gear), rotational coupling extending to third neighbour linkers (First Gear), in-plane partnered linker coupling (Second Gear), and uncoupled, independent rotation at large volumes (Neutral Gear). Together, these results establish framework breathing as a molecular gearbox that switches both the speed and collective coupling of linker rotation. Framework flexibility therefore offers a handle for programming collective motion in solid-state molecular machines.
Materials Science (cond-mat.mtrl-sci)
12 pages, 6 figures
Where Does the Anion-Redox Hole Go? Reliability of Open-Shell Projection-Based Embedding for Li-Rich Cathodes, from DFT Environments to Quantum Solvers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Pritam Das, Satadeep Bhattacharjee, Pil-Ryung Cha
Anion redox in Li-rich layered oxides places holes on oxygen next to an antiferromagnetic Mn(IV) d3 lattice, a strongly correlated open-shell problem for which projection-based wavefunction-in-DFT embedding offers a route to correlated and quantum solvers, but whose errors are known mainly for closed-shell molecules. We develop a spin-unrestricted projection-based embedding, exact at the DFT-in-DFT level to the microhartree scale for closed-shell, broken-symmetry and high-spin references with point charges, and apply DMRG-in-DFT to point-charge clusters of delithiated Li(2-x)MnO3, varying the environment functional (0-100% exact exchange), geometry, active region, active-space spin, virtual space, cluster size and magnetic reference. In every setting the lowest SCF state places the hole on an oxygen pair, with no O-O bond. How the hole is shared depends on the functional together with the geometry: hybrids give a full, uncoupled hole at the DFT+U geometry but a partial, weakly covalent hole at their own geometry, a change of up to 0.5 e on one oxygen. Where spin spreads across the active/environment boundary, the integer spin projection of the active space becomes a choice worth up to 0.26 e, and at most 0.09 e once the two Mn neighbors are included. An extended state search found missed lower states for two functionals, changing a pair-oxygen spin by up to 0.45 e. Across all 82 runs the embedded mean field gives the same hole (median DMRG change 0.02-0.04 e); correlation mainly adds O-O covalency. State control and geometry consistency, not the solver, dominate the uncertainty, and total energies are not converged at 30-40 orbitals. For quantum solvers, the embedded Hamiltonian must be spin-unrestricted: a shared-orbital form reverses the hole, while sample-based quantum diagonalization reproduces exact diagonalization, as accurately as, but not better than, classical selected CI.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Chemical Physics (physics.chem-ph)
49 pages, 8 figures
Kinetic Slush in Dissipative Rydberg Arrays
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
Hufeng Wen, Ya-Xin Xiang, Qun-Li Lei, Thomas Pohl, Zhengyang Bai, Yu-Qiang Ma
We investigate the nonequilibrium dynamics of a kinetic slush state realized via facilitated excitations in a two-dimensional dissipative Rydberg atom array. Utilizing kinetic Monte Carlo simulations in the strong dephasing regime, we show that tuning the laser detuning to compensate for nearest-neighbor interactions enables facilitated dynamics, while residual next-nearest-neighbor interactions induce kinetic frustration. This competition gives rise to an emergent slush phase characterized by pronounced dynamical heterogeneity and the coexistence of liquid- and solid-like configurations. By probing its nonequilibrium real-time evolution, we uncover a dynamical crossover from isotropic spreading to one-dimensional constrained growth, which can be continuously tuned by the frustration strength. Within this crossover regime, the slush dynamics generate fractal cluster geometries and generalized Ornstein-Zernike spatial correlations. Finite-size scaling analysis supports the system’s proximity to criticality. Our findings establish driven-dissipative Rydberg systems as a highly controllable platform for engineering complex nonequilibrium soft-matter phenomena.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Atom as an Agent: Emergent Order by Collective Predictive Coding
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
Koji Hashimoto, Tadahiro Taniguchi
What is the intrinsic reason of emergence of macroscopic order parameter out of microscopic systems? In this article, we apply to physics the collective predictive coding (CPC), the theory of language/symbol emergence. As our language emerges out of our human communications, physical macroscopic order parameter emerges out of communications among atoms — each atom is regarded as an agent who predicts each other’s behavior through inference. We present three examples of classical spin systems: two-dimensional ferromagnetic and antiferromagnetic Ising models, a two-dimensional spin model with competing stripe orders, and the fully connected Sherrington–Kirkpatrick spin-glass model. In all of these examples, proper macroscopic order parameters including the replica overlap emerge automatically through communication informatics of CPC, only from observed spin configurations. We call the learned macroscopic coordinate the collective predictive order. Furthermore, for the ferromagnetic and antiferromagnetic Ising models, the equilibrium distribution of the collective predictive order yields an emergent potential with the symmetry and thermal evolution characteristic of a Landau potential. Notably, the emergence of the collective predictive order does not refer to any structure of microscopic Hamiltonians/Lagrangians. Thus our ``Atom-as-an-Agent” (AaaA) principle offers a completely data-driven method for the emergence of macroscopic order, that is, machine learning physics.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Artificial Intelligence (cs.AI), High Energy Physics - Theory (hep-th)
33 pages, 10 figures
Robustness of Anyonic Time-Domain Interference Against Dephasing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Hai-Dong Li, Hao-Xiang Long, Gu Zhang, D. Y. Xing, Wei Chen
Recent anyon-collider experiments have identified time-domain braiding (TDB) as a new route to probing anyonic statistics. However, how such time-domain interference responds to environmental noise remains an open question. Here we show that TDB interference is intrinsically more robust than its spatial counterpart. In conventional spatial interference, environmental noise induces phase fluctuations that accumulate throughout all paths, leading to exponential suppression of the interference as the dephasing rate increases. In TDB, by contrast, the interfering temporal paths experience largely overlapping environmental fluctuations, whose contributions cancel out in the relative phase, so that only a small nonoverlapping temporal window contributes to dephasing. As a result, TDB interference decays only algebraically with the dephasing rate, providing a new experimental hallmark for its identification. We propose a Fabry-Perot fractional quantum Hall setup in which both types of interference coexist and experience the same environmental noise, enabling a direct comparison of their dephasing behaviors. Our results establish robustness against dephasing as a fundamental advantage of TDB and suggest new opportunities for exploiting anyonic interference in noisy mesoscopic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 3 figures; Supplemental Material: 16 pages, 1 figure
Fracture Mechanics and Self-Healing in Molecular Crystal Resonators for Lasing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Melchi Chosenyah, Vuppu Vinay Pradeep Kapil Yadav, Ankur Khapre, Biswajit Kumar Barman, Raghavaiah Pallepogu, Rajadurai Chandrasekar
Microscale damage poses a significant challenge to the reliability and longevity of miniaturized photonic devices; however, the mechanisms and repair of microscopic cracks and fractures in organic optical crystals remain largely unexplored. Here, we employ a mechanophotonic approach to induce microscale cracks and complete fractures in single crystals of 3-[4-(dimethylamino)phenyl]-1-(2-hydroxyphenyl)prop-2-en-1-one (HDMAC) using an atomic force microscopy (AFM) cantilever tip. We demonstrate the self-healing capability of these crystals while retaining their optical waveguiding and resonator properties, which are essential for lasing applications. HDMAC microcrystals exhibit self-healing of cracks introduced along the (010) and (001) crystallographic planes, demonstrating the versatility of this phenomenon across distinct crystal orientations. Furthermore, we identify different fracture mechanisms and establish a comprehensive assessment of healing efficiency by integrating optical loss measurements, resonator characteristics, and nanomechanical analyses. This multifaceted approach enables fair evaluation of the recovery of structural integrity and photonic functionality following self-healing.
Materials Science (cond-mat.mtrl-sci)
21 pages, 6 figures
Ground-State Properties of a Lattice-Coupled Strongly Correlated Model for Solid Oxygen under Pressure
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Naomichi Sato, Makoto Naka, Joji Nasu
Solid oxygen is an $ S=1$ molecular magnet with strong
coupling between spin and lattice degrees of freedom.
Recent studies suggest that magnetic moments
coexist with tetramer distortions under pressure.
We derive an effective spin Hamiltonian from a two-orbital
Peierls–Hubbard model with spin-orbit coupling.
The resulting model contains competing easy-plane
single-ion and easy-axis exchange anisotropies.
We analyze this model on a square lattice using quantum Monte Carlo simulations
and evaluate the magnetic contribution to the lattice stiffness
for several lattice distortion patterns including the tetramer pattern.
We find that the tetramer pattern is the most favorable
among the considered distortion patterns throughout the parameter range studied.
Moreover, competition between the two anisotropies
enhances the tendency toward lattice distortion
and strengthens the preference for tetramerization over the other patterns.
Strongly Correlated Electrons (cond-mat.str-el)
In-situ Control of the Photon-Magnon Synchronized Mode in a Miniaturized Magnetometer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Yuting Shi, Xudong Wang, Yue Zhao, Lijun Yan, Bimu Yao, Shishen Yan, Lihui Bai, Jinwei Rao
Photon-magnon synchronized modes (PMSMs) provide a route for magnetic-field sensing by exploiting their enhanced field responsivity due to cusp points (CPs). However, the previous PMSM magnetometer relies on bulky discrete components and lacks in situ control of photon-magnon interactions, limiting its integration and adaptability. Here, we demonstrate a miniaturized PMSM magnetometer integrated on a printed circuit board. A variable resistor is used to tune the photon-magnon coupling strength in situ. By adjusting the variable resistor, the electromagnetic boundary condition of the magnetometer is altered; hence, the reservoir-mediated photon-magnon interaction is changed. The coupling strength shows a non-monotonic dependence on the reflection coefficient adjusted by the variable resistor and reaches its minimum at the impedance matching condition. Furthermore, we develop a non-Hermitian model with standing-wave interference to describe the PMSM dispersion and derive the critical condition for CP formation. This work realizes a compact and tunable PMSM magnetometer and provides a pathway for controlling photon-magnon interactions in integrated magnetic sensing systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Intercomponent vortex interaction and dynamics in a uniform Bose quantum liquid
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
Rabeea Kiran, Hiroki Saito, Hsiang-Hua Jen
We investigate the interaction and dynamics of vortices belonging to different components of a binary uniform quantum liquid. Using the coupled extended Gross-Pitaevskii equations with logarithmic beyond-mean-field corrections, we derive the asymptotic interaction potential between well-separated vortices. The interaction potential retains the asymptotic form $ s^{-2}$ as a function of the intervortex distance s, but its coefficient depends on the background density through the quantum fluctuation. As a result, the interaction between vortices changes from attractive to repulsive at a critical density. Real-time simulations demonstrate a corresponding reversal of orbital motion of a vortex pair from clockwise to counterclockwise, consistent with their Magnus response.
Quantum Gases (cond-mat.quant-gas)
10 pages, 5 figures, 2 animations
Magnon Super-Bloch Oscillations and Switchable Transport in Driven Magnonic Crystals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Xiang Liu, Xi-guang Wang, Zhi-xiong Li, Xiufeng Han, Guang-hua Guo
Super-Bloch oscillations (SBOs) offer a powerful route to control wave packet propagation in driven lattices, yet their realization in magnonic systems has remained elusive. Here, we predict SBOs of magnon wave packets in periodic magnonic crystals driven by static and ac gradients of magnetic anisotropy field. A static gradient alone induces magnon Bloch oscillation (BO) with a constant carrier frequency. Remarkably, adding a near-resonant MHz-scale ac driving gives rise to a slow large-amplitude envelope oscillation, the hallmark of SBO. At exact resonance, the ac driving enables phase-controlled directional transport with a carrier-frequency shift up to GHz scale. Consequently, the same structure can be switched among three distinct regimes: conventional BO, SBO, and directed transport. Analytical expressions for the oscillation amplitudes, superperiod, drift velocity, and frequency evolution are validated by micromagnetic simulations. Extending to antiferromagnet magnonic crystals, we further demonstrate that these effects drive opposite motions of two oppositely polarized magnon modes in THz range. Our work establishes magnon SBOs as a versatile platform, opening a new avenue for reconfigurable magnonic devices.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 4 figures
Algebraic flat bands and even central-band Chern numbers in a seven-orbital hopping model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Weizhuo Xu, Jiachen Qian, Shuaihua Zhang, Yanling Wu, Jun Li
Turning a flat-band parent into an isolated Chern band requires supervise of destructive interference, hopping phases, and the cell translations of the bonds. We study this connection in a seven-orbital 2 times 2 supercell honeycomb-vacancy lattice, combining analytic reductions with Bloch spectra, lattice Chern invariants, and quantum geometry. The parent lattice has three exact flat branches, a smooth periodic zero mode, and a compact localized state. A uniform gap bound shows that faint intracell-loop hopping preserves two topologically trivial insulating gaps. The intracell hopping graph also admits a staggered chiral coloring: reversing site amplitudes according to this coloring links opposite energies at momenta separated by half a reciprocal period. This constraint restricts the isolated central band to even Chern numbers and forbids a zero-energy insulating filling at every loop phase. Purely imaginary loop hopping admits a real gauge, whereas other phases allow paired band contacts connecting central bands with C3=2 and C3=4. On a specified strong-loop cut, third-order masses open the direct gaps; these gaps shrink faster than the bandwidth as the coupling grows. Changing the bond connectivity to an oriented honeycomb next-nearest-neighbor extension generates a narrower Chern band with nonuniform quantum geometry. These results distinguish individual-band topology from occupied-group topology and reveal how bond connectivity and cell translations determine which topological bands can emerge from an exactly flat parent.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Spatial localization of magnetic-branch force contrasts in substitutional Mn-doped Ge: A first-principles study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Magnetic energy gaps do not reveal the spatial distribution of magnetic-state-dependent atomic forces. We compare ferromagnetic and antiferromagnetic forces at identical nuclear positions in 64-site substitutional Mn-doped Ge using collinear PBE calculations. For nearest-neighbour Mn pairs, the radial force projection reverses sign between magnetic branches. In the second-neighbour geometry, the shared Ge neighbour has the largest force contrast, about 2.2 times that of equally near Ge sites coordinated to one Mn. Bridge-displacement gap slopes agree with direct force derivatives across four numerical settings. Tightening the electronic threshold by 100-fold preserves magnetic ordering and the leading site, while the force-contrast vector changes by 1.08% despite a nearly unchanged energy gap. The results identify coordination-associated localization of magnetic-branch force contrasts within the frozen model, without establishing relaxed distortions, full numerical convergence or a unique exchange mechanism.
Materials Science (cond-mat.mtrl-sci)
Submitted to Physica B: Condensed Matter. Includes Supplementary Information
Antisymmetric thermopower without magnetism in three-phase composites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
A thermopower that turns a temperature gradient into a perpendicular electric field in every in-plane direction has relied on magnetism. Reciprocity permits it without magnetism, yet under a three-fold or higher axis it vanishes both in reciprocal elastic band transport and in composites of two isotropic phases with ideal interfaces. Here we show that composites of three isotropic phases carry it, and that under such an axis three is the minimum. A third, linearly independent transport matrix escapes the exact two-phase reduction; at weak contrast the first allowed axial term is cubic, proportional to a determinant of the three matrices times material-weighted, handed three-point correlations. Treating the phases as colours identifies the arrangements that allow the response, and crystal nets from reticular chemistry supply printable three-dimensional ones. Certified two-sided bounds give axial Seebeck coefficients of 49.5-50.2 $ \mu$ V K$ ^{-1}$ in a planar cell and 76-84 $ \mu$ V K$ ^{-1}$ in a printable woodpile; reflections in planes containing the axis reverse the response, and recolouring 24 nets to restore their parent symmetry switches it off. Around a line heat source the axial driving field has the $ 1/r$ azimuthal form of the magnetic field of a straight wire and drives circulating currents.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
31 pages, 6 figures, 4 Extended Data figures; Supplementary Information (43 pages) included. Code and data: this https URL (Zenodo DOI https://doi.org/10.5281/zenodo.23668925)
Tribocharging of Granular Materials Dictated by Geometric and Thermoelectric Effects
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Donggeun Kang, Ji-Ho Mun, Seungil Baek, Jaeuk Seo, Sirichok Jungthawan, Yong Woon Kim, Yong-Hyun Kim
Tribocharging of granular materials is a widespread phenomenon ranging from volcanic eruptions and dust storms to pharmaceutical processing, yet its underlying mechanism remains elusive. Recent thermoelectric models have provided a quantitative framework for triboelectric charge transfer, but they have difficulty accounting for charging between identical materials. In this Letter, we propose a theory of granular tribocharging based on the interplay between particle geometry and thermoelectric response. Collision-induced frictional heating produces a size-dependent temperature asymmetry between particles, generating a thermoelectric voltage that drives charge transfer. The sign of the Seebeck coefficient determines the charging polarity, while particle size and thermal properties set its magnitude. Our multi-collision theory explains the experimentally observed size- and material-dependent reversal of charging polarity, as in quartz and nylon.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
14 pages, 4 figures, supplemental materials
Charge density-supervised real-space representations for atomistic energy prediction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Heting Liao, Masato Wakeda, Takahito Ohmura
Ground-state electron density contains sufficient information to determine ground-state energy, while providing spatial electronic information. This study developed a charge-density-informed graph neural network (hereafter CDGNN) that jointly learns energy and valence electron density from equivariant atomic graphs. This approach incorporates density-supervised real-space probe representations into the global energy regressor, allowing density-related spatial information to contribute to energy prediction. On the QM9 dataset, CDGNN reduced the energy prediction errors relative to an equivariant GNN baseline for interpolation and extrapolation to larger molecules. For small H-containing Fe and Fe-C datasets, CDGNN performed similarly to the baseline, indicating the dataset-dependent benefits of density supervision. CDGNN also accurately predicted the charge density distributions for molecular and Fe-based systems. The attention analysis showed higher weights for probe representations near the H atoms in Fe-based structures. These findings highlight the potential of integrating charge-density information for energy prediction and its task-dependent benefits.
Materials Science (cond-mat.mtrl-sci)
Real-Space Selection Rule for Moiré Exciton-Phonon Coupling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Yixuan Liu, Shiyu Peng, Yifan Wang, Peiyao Qin, Wang Yao, Chen Hu
Exciton-phonon coupling (ExPC) governs energy relaxation and exciton dynamics in photoexcited quantum materials. Recent advances have revealed rich and tunable excitonic phenomena in moiré superlattices, yet the microscopic mechanisms underlying the coupling between moiré excitons and moiré phonons remain elusive. Here, we develop a real-space representation for moiré ExPC based on a unified theoretical framework combining the many-body Bethe-Salpeter equation with phonon perturbation theory. Furthermore, we uncover a general real-space selection rule: the spatial matching of a moiré exciton’s electron and hole densities with the moiré-phonon-induced potential perturbations determines their individual coupling contributions, while coherent interference between the electron and hole contributions controls the total ExPC. We demonstrate this rule in prototypical WSe2/WS2 moiré heterobilayers, revealing pronounced exciton- and phonon-mode-dependent coupling, including nearly complete suppression of ExPC through destructive electron-hole interference. These findings establish the internal electron-hole spatial configuration of moiré excitons as a key degree of freedom governing the strength and mode selectivity of their coupling to moiré phonons, opening opportunities to engineer ExPC through spatially tailored moiré potentials.
Materials Science (cond-mat.mtrl-sci)
Stripe antiferromagnetic order and spin dynamics in the Shastry-Sutherland Ising compound Er2Be2GeO7
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Donger Cheng, Otkur Omar, Wenbin Wei, Jan Peter Embs, Xiao Wang, Cheng Su, Hui Cheng, Zhengdong Fu, Xinzhi Liu, Wentao Jin, Ze Hu, Wei Luo, Liming Wang, Jiazheng Hao, Feiran Shen, Lunhua He, Shang Gao, Erxi Feng
In rare-earth compounds, the interplay between geometric frustration and unusual single-ion anisotropy caused by the crystal electric field often leads to exotic magnetic phases. Here, we investigate the magnetic properties of the rare-earth Shastry-Sutherland compound Er$ _2$ Be$ _2$ GeO$ _7$ using bulk measurements and neutron scattering down to sub-Kelvin temperatures. A $ k=(0,0,0)$ stripe-like antiferromagnetic order with locally tilted Er$ ^{3+}$ moments is revealed by time-of-flight neutron powder diffraction, accompanied with a $ \lambda$ -shape specific-heat anomaly at $ T_N=0.84$ K. The temperature dependence of the magnetic peak intensity corresponding to the ordered moment of Er$ ^{3+}$ approximates to the two-dimensional Ising universality class. Thermal- and cold-neutron inelastic scattering experiments demonstrate that the strong Ising anisotropy originates from the local crystal electric field, and reveal gapped magnetic excitations with weak dispersion in the ordered state. Mean-field random-phase approximation with inequivalent nearest-neighbor couplings accounts well for the collective excitations, while classical Monte Carlo simulations yield the fractional $ 1/4$ and $ 1/2$ magnetization plateaus. Our work provides a comprehensive description of the spin correlations in Er$ _2$ Be$ _2$ GeO$ _7$ with a particular focus on the classical origin of its fractional magnetization plateaus.
Strongly Correlated Electrons (cond-mat.str-el)
Mixed symmetries in active non-reciprocal systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Yuv Agarwal, Ylann Rouzaire, Daniel J. G. Pearce
Active materials are driven out of equilibrium at the microscopic scale and display diverse phenomenology; non-reciprocity is a subclass of activity in which action-reaction symmetry is also broken. These models are often grouped by the order of symmetry of their components, such as polar bird flocks or hexatic cellular tissues. However, many biological examples exist in which the components appear to have two or more symmetries simultaneously. To study this effect we introduce two independently controllable symmetries to the non-reciprocal XY model. This lattice model demonstrates wide ranging behavior dictated by the chosen symmetries. We derive a full hydrodynamic description of our lattice model that highlights the mechanisms driving its behavior. Each combination of symmetries can lead to a different hydrodynamic model with one or two simultaneous order parameters with different levels of orientational order that can appear active or not.
Soft Condensed Matter (cond-mat.soft)
33 pages, 11 figures
Kinetic Sectors and Nonequilibrium Dynamics in the $δ$-Ising Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Dehen Cao, Wei Jiang, Ya Zhang
We introduce and analyze the $ \delta$ -Ising model, a kinetic Ising ferromagnet in which single-spin flips are accepted when their energy change does not exceed a tunable threshold. Varying the field and threshold opens or closes local flip channels, dividing parameter space into kinetic sectors, each governed by a fixed Markov transition operator. We prove that the dynamics retains global spin-inversion symmetry exactly when up and down spins have equal numbers of open channels. In one such sector on a periodic chain of length $ L$ , unbiased random initial states therefore reach the field-aligned and antifield states with probability $ 1/2$ each. Closing a single channel leaves both states absorbing but makes the probability of ordering against the field decay as $ (2/\pi)^L$ . Parameter sweeps correspond to ordered products of sector operators, which separate reaching a state from holding it, so hysteresis appears when a state is reached and released at different sector boundaries. We also show how increasing the system size can induce a Mpemba-like reversal, allowing a state with more misaligned spins to reach the final ordered state sooner on average. On a periodic chain, this reversal arises because the mean absorption time grows logarithmically with system size for many short domains but linearly for a single macroscopic domain, and it disappears when the bulk flip channel is opened. These findings show how a simple, intuitive rule for Ising dynamics links local kinetic constraints to field response, memory, and relaxation within a unified framework.
Statistical Mechanics (cond-mat.stat-mech)
Magnetic Imaging with High Spatial Resolution Using a Single Niobium-Nitride-Based Three-Dimensional Nanobridge Junction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Yinping Pan, Yue Wang, Xinxin Fan, Xu Liu, Shirui Liu, Xiaoyu Liu, Ling Wu, Lu Zhang, Wei Peng, Jie Ren, Jiamin Xiong, Hao Li, Lixing You, Zhen Wang, Lei Chen
The nanobridge junctions (NBJs) allow the miniaturization of the Superconducting Quantum Interference Device (SQUID) and improve the spatial resolution of scanning SQUID microscopy. However, the SQUID loop diameter imposed a fundamental limit on the resolution. In this work, we proposed a single niobium-nitride-based three-dimensional nanobridge junction (NbN-3D-NBJ) alternative to the nanoSQUID for high-resolution magnetic imaging. The critical current of an NbN-3D-NBJ showed an nearly monotonic dependence on the external magnetic field, enabling nanoscale mapping of the magnetic field distribution by measuring the junction’s critical current with an intrinsic noise level of 100 nT/Hz^1/2. Using a NbN-3D-NBJ probe, we successfully imaged an Abrikosov vortex in a niobium film with a minimal full width at half maxima (FWHM) of 530 nm, constrained by the distance from the junction to the probe tip edge. Furthermore, we resolved 80 nm spacings between the superconducting nanowires utilizing a second probe with an optimized junction-to-tip distance. Thus, the single 3D NbN NBJ probe has been demonstrated as an effective approach for magnetic imaging with ultra-high spatial resolution.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
ACS Nano 19, 33789 (2025)
HorizON: A Multi-Horizon Deep Operator Network for Property Prediction of Organic Battery Stacks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Subhash V.S. Ganti, Lukas Woelfel, Arla Diengdoh, Tzvetan Mihaylov, Thomas Nevolianis, Jan Meyer, Christopher Kuenneth
Transition-metal-based batteries rely on critical elements such as lithium, cobalt, and nickel. Their extraction creates environmental and supply-chain challenges. Organic electrode materials (OEMs) reduce this reliance and provide broad molecular tunability. However, OEM-based batteries still show limited long-term cycling stability. Their design also requires the joint optimization of coupled metrics such as voltage, specific capacity, capacity retention, and energy density. These metrics depend on the full battery stack and on the interactions among its components rather than on the active material alone. In our previous work, we developed a data-fusion multi-task framework for average discharge voltage and first-cycle specific capacity. Both targets are single-valued. Here, we extend that framework to multi-horizon prediction by predicting a property at every cycle of a discharge trajectory rather than at a single cycle. Our multi-fidelity and Multi-horizon Deep Operator Network learns DFT redox potentials and cycle-dependent specific-capacity trajectories within one model. We train it on complete battery-stack representations and usage conditions, so it learns battery-stack interactions rather than cathode-only effects. This framework supports long-term property prediction, inverse design, and process optimization for organic battery systems.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Stability reversal, activated escape, and mechanical response of negative-mobility particles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Understanding the fluctuations and response of particles in potential landscapes is a fundamental problem in nonequilibrium statistical physics. Here, we investigate how negative mobility reshapes the stochastic behavior of a particle moving in a mechanical potential landscape. We consider a one-dimensional overdamped particle subject to additive noise, with mobility that is negative at weak forces and positive at strong forces. In a potential well, negative mobility destabilizes the mechanical potential minimum and produces bimodal localization at two off-center positions. The same stability reversal transforms conventional Kramers escape from a potential well into a two-stage escape process involving an intermediate metastable state. When an additional spatially uniform force is applied, the mechanical perturbation translates rather than tilts the effective double well, yielding a positive response dominated at weak noise by intrawell relaxation, even though slow interwell switching dominates spontaneous positional fluctuations. These findings reveal how negative mobility reshapes the interplay among mechanical landscapes, stochastic stability, and response.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Spin-polarized tunneling from a Kondo insulator: equilibrium surface magnetism versus magneto-electric response in SmB$_6$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Maxim Dzero, Brian M. Andersen
We theoretically analyze the spin-polarized tunneling between SmB$ _6$ tip and the bicollinear antiferromagnet Fe$ _{1+x}$ Te. The emergence of magnetic contrast in tunneling requires time-reversal symmetry breaking on the surface of the tip. The magnetic contrast part of the tunneling conductance then has two contributions: the first one originates from the magnetic moment due to the equilibrium long-range order on the surface, while the other is governed by the magnetic moment induced by the electric field of the junction through the surface magneto-electric effect. We show that the ratio of the equilibrium moment to the response extracted near zero bias equals, up to the sign, twice the bias at which the contrast changes sign, independently of the relative strength of the two mechanisms, so that this ratio itself does not measure the strength of the magneto-electric effect. We find that within the experimental energy window $ |eV|\lesssim10$ ~meV the {bias-dependent} field-induced contribution is at most a few percent of the equilibrium one, and the two become comparable only at biases of order $ 100$ ~meV or higher. The ratio of the field-induced to the equilibrium contribution is inversely proportional to the distance between the tip and the substrate.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 3 figures
ZnO/Ni interface-activated enhancement of spintronic terahertz emission from Ni/Pt bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Jia Xu, Shaohua Zhang, Xianguo Jiang, Lei Hao, Yaxuan Jin, Ning Yang, Yao Wang, Tong Fu, Hao Meng, Chao Lu, Wendeng Huang, Chao Zhou
Spintronic terahertz (THz) emitters based on ferromagnet/heavy-metal bilayers provide an efficient route for generating broadband THz radiation through ultrafast spin-to-charge conversion. However, Ni/Pt bilayers usually exhibit relatively weak THz emission, limiting their use as efficient spintronic emitters. Here, we report an interface-assisted enhancement of THz emission in ZnO/Ni/Pt heterostructures. By placing ZnO underneath Ni while preserving the direct Ni/Pt contact, the THz amplitude is increased by up to approximately 2.8 times compared with the Ni/Pt reference. The enhanced emission reverses polarity with the magnetic field and follows the expected angular dependence of ultrafast spin-to-charge conversion. ZnO-, Ni-, and Pt-thickness-dependent measurements show that the emission remains governed by the Ni/Pt conversion process but is strongly affected by the ZnO/Ni bottom interface. Control samples with Al2O3, Cu, and Fe further exclude a simple underlayer, optical, or growth-quality origin. The enhancement is attributed to a short-range ZnO/Ni interface effect, possibly involving oxygen-related defects, interfacial electric fields, and modification of the Ni interfacial state. This work provides a semiconductor/ferromagnet interface-engineering strategy for activating weak Ni/Pt spintronic THz emitters.
Materials Science (cond-mat.mtrl-sci)
17 pages, 4 figures
Replica Analysis of Overfitting in Vector Generalized Linear Models
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
We show how the successful recent statistical physics based theory of overfitting in Generalized Linear Models (GLMs) can be generalized to a much larger family of regression models: the so-called Vector Generalized Linear Models (VGLMs), in which not a single linear combination of covariates drives the outcome, but where one has an arbitrary finite number of such linear combinations. The latter more general and complex models can describe more sophisticated statistical patterns in data, but are even more prone to overfitting than GLMs due to their significantly larger number of parameters; this often limits their use. We show that the generalization of the overfitting theory from GLMs to VGLMs causes many mathematical challenges that were absent from the earlier work, mostly related to the increased dimensional complexity of all order parameters in the theory, but that the new problem is once more solvable using the replica method. This opens up the field to many novel and welcome applications, especially in post-genome medical inference and data analysis, where overfitting is and remains a major barrier to progress. After developing the general VGLM overfitting theory, within the replica symmetric (RS) ansatz, we illustrate its merits and its correctness via application to several relevant VGLM regression models.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
47 pages, 9 figures
The role of A in ARPES
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Angle-resolved photoemission spectroscopy (ARPES) was developed in the 1970s-1990s as a momentum-resolved probe of the electronic structure of solids, with its basic principles summarized in early seminal works and classic reviews. The basic ARPES result is currently almost exclusively associated with the two-dimensional intensity distribution with coordinate axes labeled as Binding Energy and Momentum. Such datasets are usually directly compared to the band structure calculations along high symmetry directions of the Brillouin zone. Here we show that this is the result of an oversimplified treatment of the ARPES data leading to incorrect interpretations of the experimental results. We suggest practical ways of how to avoid it in both data collection and analysis.
Materials Science (cond-mat.mtrl-sci)
9 pages, 4 figures
Borisenko, S. (2026). J. Synchrotron Rad. 33, 693-697
Impurity-induced trimer formation across the BCS-BEC crossover
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
By means of diffusion Monte Carlo calculations, we study the behavior of a single impurity embedded in two balanced Fermi baths across the BCS-BEC crossover. The impurity interacts attractively with both baths through Pöschl-Teller potentials of different strengths. That interaction is such that does not support an impurity–bath two-body bound state. When that attraction is sufficiently strong, we observe the formation of trimers composed of the impurity and one atom from each bath. These clusters are Borromean on the BCS side, where no two-body subsystem is bound, and evolve continuously into tango-like trimers on the BEC side. Subtracting from the total energy the binding energy of one trimer and that of the remaining bath-bath dimers restores the equation of state of the impurity-free system, supporting a dilute-cluster interpretation. The analysis of interparticle distances shows that the embedded trimer is not simply a dimer dressed by the impurity, but a genuine three-body cluster formed inside the two Fermi baths.
Quantum Gases (cond-mat.quant-gas)
Structural supermodulation enables resonant Raman determination of crystalline orientation in Bi2Sr2CaCu2O8+x flakes
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Flavia Lo Sardo, Tommaso Confalone, Shreya Kumbhakar, Genda Gu, Ahmad Omar, Christian G.F. Blum, Daniel Wolf, Davide Massarotti, Francesco Tafuri, Axel Lubk, Kornelius Nielsch, Nicola Poccia, Golam Haider
Bi2Sr2CaCu2O8+x (Bi-2212) is a d-wave superconductor with unconventional properties intrinsic to the material itself. These properties are of growing interest for quantum technologies in electronics and photonics, and twisted Josephson junctions can make direct use of them. However, Bi-2212 is strongly anisotropic, and it is challenging to find its crystal axes in flakes in advance, which limits device engineering. Here, we show that polarized resonant Raman spectroscopy reveals the orientation of both the a and b axes of Bi-2212 optically and non-destructively. By correlating Laue diffraction, HAADF-STEM and polarized Raman scattering on the same bulk crystal, we assign the b axis, along which the incommensurate structural supermodulation propagates, to the intensity maximum of the 27 cm-1 supermodulation mode, which varies in counter-phase with the 118 cm-1 Bi/Sr mode, along the a axis. Multi-wavelength measurements (458, 532, 660 nm) show that resulting in-plane contrast peaks at 532 nm and nearly vanishes at 660 nm, indicating that the anisotropy originates from an electronic resonance induced by the supermodulation. Using this resonance, we determine the crystallographic axes of exfoliated flakes and access their symmetry channels, providing a rapid orientation tool for cuprate van der Waals heterostructures.
Superconductivity (cond-mat.supr-con)
Spontaneous topological diode effect induced by non-coplanar antiferromagnetic order
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Nguyen Duy Khanh, Hirotaka Takagi, Rina Takagi, Susumu Minami, Tatsuto Hatanaka, Hikaru Watanabe, Michi-To Suzuki, Yuki Yanagi, Aki Kitaori, Takuya Nomoto, Ryotaro Arita, Shinichiro Seki
In non-centrosymmetric bulk materials, electrons flowing in the opposite directions often exhibit different properties. This diode-like effect (i.e., non-reciprocal electron transport) typically originates from relativistic spin-orbit coupling, and its amplitude scales with external magnetic field or magnetization in ferromagnets. Although such rectification is usually absent in antiferromagnets at zero field, recent theories predict that non-coplanar antiferromagnetic order can host large non-reciprocity even without spin-orbit coupling, magnetization or external magnetic fields. This phenomenon - the spontaneous topological diode effect - can potentially be used for efficient electrical readout of antiferromagnetic domains, while it has not been verified for real materials. Here, we report the observation of this effect in a chiral-lattice non-coplanar antiferromagnet CoTa3S6. Nonlinear resistivity measurements reveal the non reciprocal nature of electron transport along the [001] direction at zero field. The observed non-reciprocity exceeds that in typical ferromagnets, whose amplitude is governed by antiferromagnetic order parameter rather than magnetization. First-principles calculations show that the non-coplanar antiferromagnetic order induces asymmetric band dispersions even without spin-orbit coupling, establishing the non-relativistic origin of the observed response. The present findings demonstrate a new mechanism for efficient electrical readout of antiferromagnetic domains, and highlight non-coplanar antiferromagnets as a promising material platform for realizing ferromagnet-like functional responses without relying on spin-orbit coupling or magnetization.
Materials Science (cond-mat.mtrl-sci)
Spin-Orbit-Torque-Driven Recurrent Motion of Synthetic Antiferromagnetic Skyrmions for Magnetic Clocking
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Sayan Mathur, Payal Bhattacharjee, Saswati Barman, Anjan Barman
Magnetic skyrmions in synthetic antiferromagnets have emerged as attractive information carriers for spintronic technologies due to their compensated topology, which mitigates the skyrmion Hall effect and facilitates reliable current-driven transport. Here we present a frequency-tunable magnetic clocking concept based on the recurring translational motion of SAF skyrmions and define the material conditions needed to realize it in a Pt/Co/Ru/Pt/Co multilayer. Using micromagnetic simulations, we investigate the combined effects of interfacial Dzyaloshinskii-Moriya interaction and interlayer Ruderman-Kittel-Kasuya-Yosida exchange coupling, delineating the parameter space in which coupled Néel-type skyrmions with opposite topological charges form a stable, topologically compensated pair. Under spin-orbit torque excitation, the SAF skyrmions exhibit resilient longitudinal transport with minimal transverse deflection using periodic boundary conditions. Periodic boundary conditions serve as an idealized model for closed-loop racetrack geometries, facilitating the study of continuous transport cycles and long-range steady-state dynamics. The oscillation frequency is readily modified by the applied current density and material characteristics, offering a pathway to field-free nanoscale timing components. Moreover, the threshold-activated initiation of recurrent transport mimics tonic-spiking behavior, indicating possible use in neuromorphic signal generation. This work establishes SAF skyrmions as versatile building elements for future spintronic functional devices by integrating topological protection, controllable transport, and cyclic dynamics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
The constrained molecular dynamics (CMD) to obtain spatio-temporal memory functions of viscoelastic liquids: stability analysis of equations of motion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Olivier Benzerara, Jörg Baschnagel, Alexander N. Semenov
Mechanical stress is one of the main characteristics of viscoelastic molecular systems, including vitrifying liquids and amorphous solids which are known to show long-range dynamical heterogeneities. It is therefore important to deal with time- and space-resolved local stress whose correlations can be used to obtain viscoelastic memory functions of such systems, in particular, their wave-vector dependent shear and compression relaxation moduli. However, such memory functions are not directly accessible within standard molecular dynamics (MD) simulations. Here we discuss a new method called the constrained molecular dynamics (CMD) which allows for a direct evaluation of the wave-vector and time dependent viscoelastic moduli. The study is focused, in particular, on the stability analysis of different variants of the CMD, revealing the most efficient stabilization algorithm. Our theoretical predictions for the time-dependence of the most important parameters (like the wave-vector resolved mass current) during the stabilization stage are compared with the simulation data using different CMD algorithms. An excellent agreement is observed, thus confirming the validity of our theoretical approach and its ability to accurately predict the most important initial part of CMD trajectories.
Soft Condensed Matter (cond-mat.soft)
34 pages, 4 figures
Prussian blue and Prussian white thin-film electrodes: Single-step electrodeposition for anode and cathode applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Michael Pohlitz, Mohammed Fayis Kalady, Larissa de O. Garcia, Lindiomar Borges de Avila Jr, Darius Pohl, Falk Röder, Flavio Abreu Araujo, Axel Lubk, Daniel Wolf, Christian K. Müller
This study examines how deposition potential influences the composition and nanoscale structure of Prussian Blue (PB)/Prussian White (PW)-family films, providing an experimental basis for assessing their proposed functions. Films were grown directly on Au/Cr/Si in a single potentiostatic step from a common aqueous bath at $ -0.20$ to $ +0.40$ ,V versus a saturated calomel electrode, with a fixed deposition charge of 10,mC. Electron microscopy, elemental analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy revealed potential-dependent chemistry and nonmonotonic morphology. EDS indicated greater K incorporation in lower-potential deposits, whose Fe~2p and Raman features were consistent with more reduced, PW-like environments. Surface K/Fe ratios varied nonmonotonically from 1.129 to 1.322 across the series, corresponding to 52.95–56.94% K within the detected K+Fe population. Larger faceted crystallites at $ +0.30$ ,V contrasted with finer pyramids and cracks at $ +0.40$ ,V. Selected PB-like and PW-like regions had local cubic lattice parameters of $ (10.31\pm0.10)$ ,Å and $ (10.36\pm0.10)$ ,Å, respectively; their overlapping uncertainties prevent discrimination by lattice spacing alone. Cross-sectional maps showed broadly uniform framework-element distributions within locally continuous coatings. Together, these observations relate deposition conditions to contrasting chemical and morphological starting states without establishing bulk stoichiometry or phase purity. A literature-grounded outlook identifies ion storage, sensing, electrochromism, resistive switching, and ion handling as research opportunities requiring functional validation in these films.
Materials Science (cond-mat.mtrl-sci)
Residual dynamics determine dissipation in strongly coupled linear Langevin systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Vansh Kharbanda, Anton F. Burnet, Benedikt Sabass
Interactions shape the properties of many physical and biological nonequilibrium systems, but whether collective operation raises or lowers entropy production remains difficult to predict. Here, we show that strong coupling suppresses irreversible circulation associated with the directly coupled degrees of freedom. In identical two-dimensional systems, this suppression is monotonic for nonzero coupling modes and guarantees a monotonic decrease of the entropy production rate (EPR), with the corresponding probability currents vanishing in the strong-coupling limit. In higher dimensions, suppressing the circulation associated with the coupled degrees of freedom does not generally eliminate all irreversible circulation, since the remaining degrees of freedom can still sustain nonequilibrium currents. The EPR of these residual dynamics sets the strong-coupling limit, providing a criterion for whether a given choice of coupled variables leads to lower dissipation than the uncoupled system. The approach to this limit depends on how the finite-coupling current correction aligns with the residual current. Further, we show that convergence to residual dynamics in the strong-coupling limit also applies to coupled non-identical systems. Finally, we demonstrate the predicted EPR reduction in nonlinear models of vertebrate hair-cell bundles and bacterial chemotaxis.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
23 pages, 8 figures
Two Exceptional-Point Regimes in the Spinterface Model of Chirality-Induced Spin Selectivity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
The spinterface model of chirality-induced spin selectivity supports two algebraically distinct near-exceptional-point (EP) regimes, which cannot be mixed. A \emph{gold-level} near-EP involves the two gold spin states under an anti-Hermitian, electrode-mediated spin flip with spin-symmetric dissipative broadening (SchemeB). A \emph{chain-level} near-EP involves the collective coalescence of the two molecular eigenstates with largest weight on the first molecular site under a Hermitian on-site Rashba spin flip with spin-dependent broadening (SchemeA). Mixing the diagonal cancellation of one scheme with the off-diagonal structure of the other yields a strictly negative discriminant and admits no EP on any parameter path, making the gold/chain classification exhaustive. At the gold near-EP the spin-flip coupling is chirality-selective, converting achiral spin-valve transport into purely chiral transport across well-defined crossover points. At the chain near-EP the Petermann factor grows as a power law in chain length, with an exponent tunable by the Rashba coherence length and non-monotonic in the Rashba strength, reflecting a balance between coherent enhancement and progressive breakdown of the Scheme-A condition. Both near-EPs are dressed versions of the ideal two-state EP, and the ratio between observed and bare EP locations measures the delocalisation of the coalescing pair, providing a fit-free diagnostic of the mechanism. These results identify CISS junctions as a solid-state platform for non-Hermitian spectral physics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Perimeter shell properties of branched polymer adsorbents in various conformational states
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Viktoria Blavatska, Jaroslav Ilnytskyi
The structural accessibility and perimeter shell properties of branched macromolecules are studied using Monte Carlo simulations on a simple cubic lattice. Constituent polymer chains of these macromolecules are constructed in an algorithmic way as: a set of collinear monomers; a self-avoiding walk (SAW); tigthly packed monomers. These mimic the ground states for a rigid rod, flexible chain, and collapsed chain conformational states, respectively. We analyzed the set of observables that are related to adsorption, such as perimeter shell size (number of available sites for particle adsorption) per monomer $ \langle \bar{n}a \rangle$ , mean coordination number of perimeter shell $ \langle n{\rm bond} \rangle$ (average number of contacts per adsorbed particle), and coordination accessibility per monomer $ \langle \bar{n}_s \rangle$ . Our results demonstrate that branching reduces the perimeter shell size while it increases mean coordination number of perimeter shell across all conformational states, due to higher local monomer density near branching cores and formation of shared adsorption sites or microcages. Stiff extended structures yield the highest values for $ \langle \bar{n}a \rangle$ (approaching $ 4$ in the limit of long chains), whereas the flexible ones provide the largest values for $ \langle n{\rm bond} \rangle$ . We can note that the collinearity of monomers in constituent chains works in the same direction as reduction of branching ($ \langle \bar{n}_a \rangle$ grows), whereas the { tight packing of them} – in the same direction as the increase of branching ($ \langle \bar{n}_a \rangle$ decreases)
Soft Condensed Matter (cond-mat.soft)
Transport statistics in asymmetric coupled chaotic dots in series: Brownian motion model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Ashutosh Dheer, Santosh Kumar, Jayendra N. Bandyopadhyay
We study statistics of transport properties in a system of two quantum chaotic cavities coupled in series through a tunable junction and connected to reservoirs with asymmetric leads. Within the random matrix theory framework and in the absence of time-reversal symmetry, the scattering matrix S undergoes a crossover from two independent circular unitary ensembles to a single CUE as the inter-cavity coupling increases. Modeling this crossover using Dyson’s Brownian motion approach, with the junction width acting as a time-like parameter, we derive closed-form expressions for the time-dependent averages and variances of conductance and shot noise power for arbitrary lead asymmetry. These analytical results reduce to known expressions in the symmetric and fully coupled limits. The mapping between the Brownian time parameter and the physical junction width is found to be observable-dependent, reflecting the different eigenfunction correlations probed by conductance and shot noise power, and this dependence is examined and separately calibrated for each observable. Validating against random-matrix simulations and tight-binding transport calculations using Kwant, we find quantitative agreement for ensemble-averaged observables throughout the crossover, while variances, being more sensitive to microscopic fluctuations, show deviations from the Brownian-motion predictions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Chaotic Dynamics (nlin.CD)
J. Phys. A: Math. Theor. 59 (2026) 415201
First-Principles Investigation of Irida-Graphane: A Wide-Band-Gap Semiconductor Derived from Irida-Graphene
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Djardiel S. Gomes, Isaac M. Félix, Marcelo L. Pereira Junior
Opening a band gap in metallic two-dimensional carbon allotropes is an important step toward their use in electronic and optoelectronic devices, and full hydrogenation has proven to be an effective route to achieve it. Here, we propose irida-graphane, the fully hydrogenated derivative of the irida-graphene, a monolayer composed of three-, six-, and eight-membered rings, and investigate its structural, mechanical, electronic, and optical properties using density functional theory (DFT) at the PBE and HSE06 levels combined with phonon and \textit{ab initio} molecular dynamics (AIMD) simulations. All carbon atoms adopt $ sp^3$ hybridization, with the hydrogen atoms of the three- and six-membered rings bonded to opposite sides of a buckled carbon framework, and the lattice parameter contracts by 4.3% with respect to irida-graphene. The hydrogenation energy of $ -0.53$ eV/H indicates that the hydrogenation of irida-graphene from molecular hydrogen is exothermic. The absence of imaginary phonon frequencies confirms the dynamical stability of irida-graphane, and AIMD simulations show that its structure remains intact at temperatures up to 2000 K. Irida-graphane is mechanically isotropic, with an in-plane stiffness of approximately 156 N/m, a Poisson’s ratio of approximately 0.1, and critical strains of approximately 20%. Hydrogenation transforms the metallic parent structure into a semiconductor with an indirect band gap of 4.68 eV (PBE) and 6.0 eV (HSE06). Irida-graphane is transparent in the visible range, with reflectivity below 0.3%, and absorbs strongly in the deep ultraviolet, with absorption coefficients of the order of $ 10^{5} - 10^{6}$ cm$ ^{-1}$ . These results suggest irida-graphane as a candidate wide-gap material for ultraviolet optoelectronics and transparent coatings.
Materials Science (cond-mat.mtrl-sci)
Langevin dynamics towards Generalized Gibbs Ensembles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
Rafael González-Albaladejo, Leticia F. Cugliandolo, Gustavo S. Lozano, Daniel A. Stariolo
In recent years, statistical physics tools have been used to study the dynamics of macroscopic quantum and classical integrable models. These studies have shown that, in the thermodynamic limit, long term time-averages of local observables equal statistical averages calculated with a Generalized Gibbs Ensemble (GGE). In the latter, the weight in phase space involves all constants of motion multiplied by Lagrange multipliers which are fixed by their initial values. We argue that the GGE can be interpreted as a proper Boltzmann measure of a different (non-standard) mechanical model. This measure can therefore be sampled with stochastic methods implemented, for example, as a Langevin process. We tailor the deterministic force in the Langevin equations so that at long times the stochastic trajectories sample the desired measure. We use the integrable Neumann Model – the model of a classical particle constrained to move on a sphere under anisotropic harmonic potentials – as a benchmark. We test the method in a setup where the Lagrange multipliers are fixed by the GGE governing the asymptotic dynamics of the isolated Neumann model following a quench. This problem has different phases depending on the initial conditions and quench protocol and, in all cases, with the stochastic evolution of an adequately tuned Langevin process we reproduce the asymptotic values of relevant observables.
Statistical Mechanics (cond-mat.stat-mech)
84 pages, 24 figures
Cu intercalation and field-driven filament formation in vertically aligned MoS$_2$ memristors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Touko Lehenkari, Hannu-Pekka Komsa
Vertically-aligned MoS$ _2$ films paired with a Cu top electrode have been used as electrochemical metallization cell memristor devices. The memristive switching has been attributed to the formation of conductive filaments, yet their exact structure has remained elusive. Here we carry out a multi-scale computational study of Cu intercalation, clustering, and field-driven dynamics to eventually model the filament formation under operating conditions. We use density-functional theory results to fine-tune a machine learning force field, and the most important physical phenomena are further distilled into multi-particle kinetic Monte Carlo simulations. By exhaustive enumeration of Cu intercalated structures, we find the most stable structure at MoS$ _2$ Cu$ _{0.11}$ composition, with Cu atoms forming a dice lattice between the MoS$ _2$ layers. These structures are shown to exhibit metallic character and can thus form conductive filaments under memristor operation. The simulated switching speed and threshold voltage agree well with the available experimental data. Our results give fundamental insights on the device operation mechanism and guidelines for maximizing switching speed and endurance.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Reconstructing chiral edge states via boundary dissipation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Xin-Ran Ma, Kui Cao, Qian Du, Zheng Wei, Su-Peng Kou
Boundary dissipation can reshape the spatial profiles and decay properties of topological edge modes in Chern insulators. We develop a microscopic boundary-channel framework to explain their decay mechanisms and determine the effective decay rates in the weak- and strong-loss regimes. By retaining the lossy outer orbitals and a normalized edge state of the Hermitian inner system, we identify a directly coupled bright boundary channel, while incorporating the remaining inner states through a Feshbach self-energy. In the Qi–Wu–Zhang model, weak-loss decay is governed to leading order by the original edge state’s probability weight on the lossy boundary, with coupling-induced corrections starting at cubic order. At strong loss, the reconstructed inner-edge state instead decays through virtual coupling to the damped bright channel, giving a rate proportional to the squared microscopic coupling and inversely proportional to the bare loss. The Haldane model shows that the same leading decay mechanism holds for a different intercell hopping structure, while additional matrix-valued self-energy feedback modifies the boundary spectrum at finite loss and shifts the exceptional-point threshold. These results provide a unified microscopic description of boundary-state reconstruction and its decay mechanisms, offering testable predictions to guide experiments in photonic crystals, phononic crystals, and topolectrical circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Phase Separation in a Mixture System of Active and Passive Particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Reo Arakaki, Tetsuya Hiraiwa, Ryo Akiyama
We carried out molecular dynamics simulations of a mixture of self-propelled particles (SPPs) and passive particles. When the self-propulsion speed was sufficiently high, the system separated into two phases. One phase consists of ordered passive particles, and the other is a disordered mixture of both particle types. The separation arises from the interplay between the self-propelled motion of SPPs and thermal motion of the passive particles, since phase separation does not appear with either particle type alone. As the self-propulsion speed increases, the SPPs push surrounding particles away, effectively increasing their excluded size. As a result, the increase in the effective excluded sizes promotes the accumulation of passive particles and the segregation of SPPs into the dilute phase through a mechanism analogous to the depletion interaction. This mechanism explains the phase separation observed in the present study. Our findings provide insights into the potential applications of SPPs and contribute to our understanding of natural systems composed of elements with different levels of motility.
Soft Condensed Matter (cond-mat.soft)
10 pages, 10 figures
Magnetic crystal generation with site-resolved magnetic moments via Gaussian-mixture retargeting and finite-budget yield prediction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Wen-Chuang Shang, Chenyu Shen, Mikito Tsujimoto, Tomonori Tanaka, Yoshihiro Gohda
We introduce GMMag, a workflow for generating crystal structures together with their site-resolved magnetic moments, built on a conditional variational autoencoder with a graph neural network encoder and a transformer decoder. Gaussian-mixture sampling redirects generation towards selected chemical and magnetic targets without retraining. We systematically investigate how encoder and decoder design, the representation of magnetic-moment magnitudes and relative signs, and sampling choices affect reconstruction, generation quality and diversity. Because a higher screening pass rate does not necessarily yield more qualifying candidates with distinct chemical formulas absent from the reference dataset, we model how repeated generation of the same chemical formulas limits their accumulation and test the model in two separate ten-million-draw runs. As an application, the workflow identifies Nd-containing candidates with chemical formulas absent from the reference dataset, negative formation energies and high estimated saturation magnetization.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Main text: 28 pages, 8 figures; Supplementary Information: 31 pages, 2 figures (included)
Enhancing magneto-optical coupling and scattering from magnetic vortices by optical polarization texturing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Vakhtang Jandieri, Chenglong Jia, Ramaz Khomeriki, Nicolas Tsagareli, Qian Li, Douglas H. Werner, Jamal Berakdar
Magnetic textures offer a route toward photonic functionality in which electromagnetic fields are controlled not only by material composition and geometry but also by the internal magnetic configuration. Conversely, spatial texturing of these fields is a qualitatively new tool to increase the effective coupling strength to magnetic matter and to act on the the vortex topology and magnetic dynamics. Here, we investigate the coupling and scattering of structured electromagnetic fields by a magnetic vortex, focusing on how spatially non-collinear magnetization governs polarization conversion, electromagnetic energy flow, and magnetization dynamics. We develop a spherical rigorous coupled-wave method that incorporates the spatially dependent anisotropic magnetic permeability associated with the vortex texture. The calculations show that the off-diagonal components of the magnetic susceptibility mediate conversion into complementary polarization channels that are absent from the incident field. The generated fields exhibit pronounced spatial localization associated with the vortex magnetization profile and support a nonzero azimuthal component of electromagnetic energy flow. A comparison between linearly and radially polarized illumination reveals an approximately one-order-of-magnitude difference in the scattered fields amplitudes due to polarization texturing, demonstrating the importance of spatial overlap between the incident field and the anisotropic magnetic response. The back-action on the magnetic vortex dynamics is quantitatively demonstrated by numerical simulations for the inverse Faraday effect due to the rectification of structured effective-field excitation. It is shown that polarization textured optical fields can drive vortex-core precession and, at sufficiently strong excitation, reverse the core polarity and chirality on nanosecond time scale.
Materials Science (cond-mat.mtrl-sci)
Magnetic structures in a model nickelate: Monte Carlo study
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
V. S. Ryumshin, Yu. D. Panov, A. S. Moskvin
Within the framework of the classical Monte Carlo method with kinematic account of constant bosons concentration a model nickelate was studied, its magnetic structures for various values of exchange integrals considering up to third-nearest neighbours were determined.
Statistical Mechanics (cond-mat.stat-mech)
Perfect sampling of Ising spin glasses with bounding chains
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
We study perfect sampling algorithms for Ising spin glasses based on coupling from the past and bounding chains, on several graph families and coupling distributions. For the single-site bounding chain, we establish coalescence in $ O(n\log n)$ updates under Dobrushin conditions. On sparse random graphs, our numerical results suggest that efficient sampling extends throughout the tree-uniqueness regime, with a slowdown beyond this threshold. On Erdős-Rényi random graphs $ \mathcal{G}(n,d/n)$ with standard Gaussian couplings, we introduce a block bounding chain and prove its coalescence in $ O(n\log n)$ block updates in the tree-uniqueness regime for sufficiently large $ d$ , each block update requiring $ O(n)$ operations, adapting a proof in~\cite{Efthymiou_Zampetakis_2024} for the rapid mixing of block Glauber dynamics. On periodic lattices, our experiments instead suggest that the single-site bounding chain is limited by the looseness of its bounding envelope, whereas on the Sherrington-Kirkpatrick model, slow coalescence is accompanied by damage spreading at every inverse temperature tested. These observations motivate alternative bounding representations and couplings as strategies to improve perfect sampling on spin glasses.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Probability (math.PR)
47 pages, 10 figures
Hydrodynamic fluctuations in Luttinger liquids
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
We develop the theory of hydrodynamic fluctuations for one-dimensional quantum liquids. At low temperatures the relaxation of interacting electrons in a single-channel wire separates into two classes: equilibration, which changes the numbers of right and left movers through backscattering and is exponentially slow, and thermalization, which redistributes energy and momentum at a fixed number of movers at a power-law rate. This separation of time scales gives the electron liquid a two-fluid description analogous to superfluid $ ^4$ He, with the zero mode of the Luttinger liquid as the superfluid component and the gas of thermal excitations as the normal component. Using Onsager reciprocity and the fluctuation-dissipation theorem, we add Langevin fluxes to the two-fluid hydrodynamic equations, including a mutual-friction noise generated by rare backscattering events that has no counterpart in helium. We apply the theory to Coulomb-coupled quantum wires and calculate the dynamic structure factors, which contain a second-sound peak next to the plasmon doublet; the Coulomb drag resistivity, where intrawire equilibration acts as a bottleneck and turns the hydrodynamic drag into an activated temperature dependence; and the near-field heat transfer between the wires. Mode frequencies, spectral weights, linewidths, and the crossover scales of the transport coefficients are expressed through the thermodynamic properties of the liquid and a few dissipative coefficients, providing spectroscopic and transport probes of two-fluid behavior in one-dimensional quantum systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Fluid Dynamics (physics.flu-dyn)
16 pages, 8 figures
Point-contact spectroscopy of electron-phonon interactions and anisotropy of superconducting energy gaps in $2H-NbS{ {e}_{2}}$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
N. L. Bobrov, L. V. Tiutrina, S. B. Feodos’ev, V. V. Fisun
The superconducting state of $ 2H-NbS{ {e}{2}}$ was studied using point contacts for two main orientations of the contact axis relative to the principal crystallographic orientations: along the $ c$ -axis and in the $ ab$ plane. For contacts oriented in the $ ab$ plane, dependencies proportional to the electron-phonon interaction function were obtained, which agree perfectly with the theoretical calculation. It was found that the features on the experimental curves associated with the electron-phonon interaction extend to energies twice the cutoff energy of the phonon spectrum and have an amplitude of the same order of magnitude throughout the entire energy range. It has been theoretically demonstrated that the features at energies exceeding the boundaries of the phonon density of states are caused by two-phonon scattering processes of non-equilibrium phonons on Andreev electrons. A criterion for the undisturbed nature of the crystal lattice in the region where gap features form has been found. Using $ 2H-NbS{ {e}{2}}-Cu$ heterocontacts in the superconducting state, a study of energy gaps was conducted for two orientations of the $ NbS{e_2}$ crystal: along the $ c$ -axis and in the $ ab$ plane. It was found that the superconducting energy gaps are anisotropic; specifically, three gaps were identified in the $ ab$ plane, whereas only two were observed in the $ c$ direction.
Superconductivity (cond-mat.supr-con)
15 pages, 10 figures
Coulomb Crystallization in Free Electron Beams
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Valerio Di Giulio, Rudolf Haindl, Armin Feist, Claus Ropers
Classical Coulomb crystals and quantum Wigner crystals typically arise when repulsive interactions order like-charged particles in spatially confined environments. Here, we show that transient crystallization can also emerge in freely propagating electron pulses without external trapping. Experimentally, we use a transmission electron microscope to measure number-resolved energy correlations in photoemitted pulses containing up to nine electrons, revealing strong correlations at small particle numbers that progressively disappear in the pulse interior as the number increases. To explain these observations, we combine many-body simulations with a one-dimensional statistical-mechanical model, showing that the leading and trailing electrons generate a self-induced longitudinal potential that transiently confines the inner particles, enabling the formation of an ordered chain during propagation. The resulting crystallization phase diagram reveals how many-body ordering dynamics can be understood in terms of evolving macroscopic beam properties, namely its geometry and the ratio of the mean Coulomb interaction energy to the longitudinal thermal energy. Extending this framework, we theoretically demonstrate that weak transverse guiding through electrostatic or optical ponderomotive forces can sustain crystallization at larger particle numbers and predict spontaneous longitudinal periodic bunching in continuous electron beams. Our results identify conditions under which stochastic Coulomb interactions can be harnessed to generate self-structured, strongly correlated electron beams in both pulsed and continuous regimes.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Accelerator Physics (physics.acc-ph)
Superconductivity and local stacking polymorphism in LaNiGa2 thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2026-10-28 20:00 EDT
Pengcheng Wang, Qingxiao Wang, Yameng Wu, Zixuan Huang, C. T. Lam, Zheyu Wang, Swee K. Goh, Xiaoying Xu, Yufan Li
LaNiGa2 has attracted considerable interest as a candidate unconventional superconductor, particularly due to its reported time-reversal symmetry breaking and nonsymmorphic crystal structure hosting symmetry-protected electronic band degeneracies. Here, we report the growth and characterization of superconducting LaNiGa2 thin films on MgO substrates by magnetron sputtering. X-ray diffraction reveals highly crystalline, (010)-oriented films with well-defined in-plane alignment and rotational twinning. Electrical transport measurements establish superconductivity with a transition temperature of approximately 1 K. Atomic-resolution transmission electron microscopy reveals local variations in crystallographic orientation and interlayer stacking, with a predominantly Cmcm structure containing minority Cmmm regions. The coexistence of these closely related structures reveals local stacking polymorphism that is difficult to distinguish using conventional X-ray diffraction. These findings establish a superconducting LaNiGa2 thin-film platform and provide new insight into the local crystal structure of a material whose electronic properties and superconducting pairing remain under active investigation.
Superconductivity (cond-mat.supr-con)
13 pages, 3 figures
Unconventional SOC-activated Altermagnetic Spin Splitting and Half-Angle Locking of Spin Transport
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Weiwei Chen, Ziyu Zhou, Pan Gao, Yanan Pan, Zhongjun Li, Ye Yang, Jianhui Zhou, Rui Wang
Conventional altermagnetic spin splitting arises from staggered exchange and sublattice-dependent anisotropic hopping without requiring spin-orbit coupling (SOC). Here we derive a low-energy effective model showing that SOC and staggered exchange can jointly activate additional spin splitting on momentum planes where the nonrelativistic contribution vanishes. In hexagonal $ \alpha$ -MnTe, this SOC-activated contribution produces d-wave spin splitting near $ \Gamma$ with out-of-plane spin polarization. Its leading angular pattern counter-rotates by half the in-plane Néel-vector rotation angle. First-principles spin-transport calculations reveal a corresponding approximate half-angle locking between the Néel-vector orientation and the electric-field directions maximizing the signed longitudinal and transverse spin conductivities. Analytical transport calculations based on the effective model trace this locking to the same angular coupling between momentum and the Néel vector that governs the spin-splitting pattern. Our findings connect the microscopic mechanism of SOC-activated altermagnetic spin splitting to directional spin transport, providing a theoretical basis for probing Néel-vector orientation and controlling spin-current generation.
Materials Science (cond-mat.mtrl-sci)
Electric Field-Induced Hole- and Electron-Type Flat Bands in Twisted Double Bilayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-10-28 20:00 EDT
Zhihao Jiang, Dongkyu Lee, Alfred J. H. Jones, Youngju Park, Paulina Majchrzak, Kimberly Hsieh, Chakradhar Sahoo, Thomas S. Nielsen, Kenji Watanabe, Takashi Taniguchi, Philip Hofmann, Yong P. Chen, Jeil Jung, Søren Ulstrup
Application of a finite electric field and small twist angle between two graphene bilayers leads to widely tunable electronic structures that support emergent phenomena. Here, we measure the electronic structure of twisted double bilayer graphene with twist angles of 3.1$ ^{\circ}$ and 6.0$ ^{\circ}$ using micro-focused angle-resolved photoemission spectroscopy (microARPES) on \textit{in situ} gated samples. At a twist angle of 6.0$ ^{\circ}$ , we find that the dispersion around the valence and conduction band extrema is unchanged compared to separate graphene bilayers, whereas electric field tunable hybridisation gaps and band flattening effects occur at higher binding energies. In the 3.1$ ^{\circ}$ structure, we find that the resulting superlattice drives dispersion changes around the valence and conduction band edges. Increasing the gate-induced doping in the bottom bilayer leads to the formation of flat bands between the valence band maximum in the bottom bilayer and conduction band minimum in the top bilayer. Our experiments establish combinations of twist angle and electric field that potentially support strong electron-hole excitations and that provide a benchmark for the theoretical description of moderately twisted double bilayer graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
19 pages, 5 figures
Advanced Electronic Materials, 2026;12:e00882
Chaos picture of spin glasses
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-10-28 20:00 EDT
The chaos picture is a novel, coherent, and intuitive theoretical framework for spin glasses, reconciling the 40-year-old droplet vs. replica symmetry breaking debate. First, we argue the formation of a hierarchical energy landscape by pinning and dynamic filtering of random droplets. As the temperature decreases, the chaos picture describes a progressive freezing of scale-dependent droplets in real space, which mirrors a hierarchical free energy landscape fracturing process in phase space. This bifurcation process is accompanied by temperature chaos, leading to dynamic pure state coexistence without violating the droplet scaling. Crucially, the interface geometry is not critical to these mechanisms, naturally incorporating the interface crossover from planar, fractal, to space-filling as the dimensionality increases, in line with the mean-field limit. Finally, the chaos picture provides profound insights into spin-glass dynamics such as aging, rejuvenation, and memory effect, while offering a streamlined reinterpretation of the complex metastate framework.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 1 figure
Molecular shape controls dipolar correlations in polar liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
The dielectric constant of polar liquids depends not only on the magnitude of the molecular dipole moment but also on short range orientational correlations between neighboring dipoles. How molecular structure determines these correlations, quantified by the Kirkwood correlation factor $ g_\mathrm{K}$ , remains unclear. Using molecular dynamics simulations of model polar liquids without hydrogen bonding, we show that molecular shape plays a central role. We interpret $ g_\mathrm{K}$ as resulting from the combination of dipolar interactions and steric effects, which together favor either alignment or antialignment of neighboring molecules. Depending on molecular shape, $ g_\mathrm{K}$ can either increases or decreases upon cooling, or change monotony. A minimal model of dipoles on a cubic lattice reproduces these three regimes and attributes the nonmonotonic case to a competition between the first layer of neighbors, which favors alignment, and the second layer, which favors antialignment.
Soft Condensed Matter (cond-mat.soft)
7 pages, 5 figures
New Developments in Diagrammatic Monte Carlo for Interacting Lattice Fermions: Efficient Algorithms and Applications
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
This thesis develops diagrammatic methods for thermodynamic and subsystem quantities of interacting lattice fermions, providing reference calculations for quantum simulators and many-body approximations. I formulate an inverse-flavour expansion about a self-consistent Hartree saddle, enumerate non-Gaussian diagrams, and use a discrete Lehmann representation to integrate selected internal vertices analytically. Density results cover 31 state points of the six-flavour Hubbard model on a $ 70\times70$ lattice at $ T/t=0.15$ .
I generalize combinatorial summation to flavour-dependent propagators and expansion shifts. CoS++ combines partial contractions to obtain connected sums for interaction subsets. A determinant-polynomial sieve evaluates the same sums through local coefficient filters; at ninth order it is 24–25 times faster than the specified CoS baselines in three-flavour dense-random-matrix benchmarks. Thermodynamic applications include a 2048-site honeycomb lattice and a three-flavour square lattice with 1024 sites.
For the second Renyi entropy, I derive a fermionic replica path integral and a stable evaluation of its two-time Green functions. The connected-determinant calculation reaches tenth order on a $ 3\times3$ cluster and ninth order on larger lattices. On $ 50\times50$ sites at $ (U/t,\mu/t,\beta t)=(3,1,8)$ , the ninth-order continuation at shift $ \alpha=1.3$ gives $ S_2/N_s=0.06695$ with propagated Monte Carlo uncertainty $ 3.0\times10^{-5}$ . Comparing two expansion shifts at their respective retained orders gives an endpoint difference of $ 2.6\times10^{-4}$ .
Strongly Correlated Electrons (cond-mat.str-el), Computational Physics (physics.comp-ph)
PhD thesis with extended derivations and additional technical details beyond those presented in the corresponding manuscripts
Back-End-Of-Line Integration of 2-Terminal Ferroelectric Hafnia Synaptic Weights on Commercial CMOS Process
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Alexander Flasby, Anwesha Panda, Nathan Savoia, Laura Bégon-Lours
Functionalising the back-end-of-line (BEOL) of CMOS with emerging materials is a key route to neural network accelerators and neuromorphic systems. In this work, we demonstrate for the first time the integration of 2-terminal ferroelectric synaptic weights in the BEOL of as-delivered commercial 180 nm CMOS dies. A novel material stack is proposed, in which a WOx/[HfO2-ZrO2] bilayer is sandwiched between TiN and Mo electrodes. For devices annealed at 450 °C, programming below 1.8 V is achieved with a cycle-to-cycle variation below 3 %. Synaptic weights annealed at 500 °C exhibit more gradual weight updates, while the tested underlying NMOS transistors remain functional after the complete integration process. The trade-off between thermal budget and on-device training performance is illustrated using hardware-aware neural network simulations.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
5 pages, 6 figures, submitted to ISCAS 2027, Special Session “Hafnia Ferroelectrics: Co-Design from Materials to Energy-Efficient AI Circuits”
Activation force dependence of the fluidization transition in supercooled active water
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Quoc Tuan Truong, Victor Teboul
Using an activation model reproducing facilitation mechanisms, we found recently a fluidization transition in supercooled water triggered by the motion of a few active molecules. We investigate here the effect of the activation force on the transition. The activation force increases the probability for active molecules to overcome the energy barrier induced by caging. The induced molecular motions result in an intermittent loose structure leading to a decrease of energy barriers around the moving molecule, thus facilitating the motion of nearby molecules. Therefore we expect the force, if small enough, to increase the facilitation mechanism, and as a result cooperative motions induced by it. As a result the activation force permits to tune facilitation and cooperative motions in active glass-formers. We find an optimum force for cooperative motions that we evaluate to be around 3.5pN, a value in the range of protein motor forces. As expected for a phase transition we observe peaks of cooperative motions (dynamic heterogeneity) on the transition. This result shows that dynamical heterogeneity are the cooperative motions of physical importance for the transition.
Soft Condensed Matter (cond-mat.soft)
Quantum critical scaling in convective active matter
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-10-28 20:00 EDT
We construct a minimal field theory for critical quantum active matter, describing a nonconserved scalar order parameter with Landau-Ginzburg ordering and self-advection. When diffusive noise dominates, higher-order quantum vertices and non-Gaussian noise fluctuations remain relevant alongside the deterministic nonlinearities, with an upper critical dimension $ d_c=2$ . A one-loop renormalization-group analysis in $ d=2-\epsilon$ reveals a purely dissipative fixed point, where nonlinear noise suppresses convection, and a quantum convective saddle, where interactions, convection, and non-Gaussian noise coexist. We determine the critical exponents, show that the convective regime is distinct from conventional Burgers hydrodynamics, and discuss how it could govern transient universal scaling in microscopic models of quantum active matter before a crossover to semi-classical dynamics.
Statistical Mechanics (cond-mat.stat-mech)
15+14 pages, 5+3 figures
Topological Criticality with Charge-(3e) Fluctuations in the (\mathrm{SU}(3)) Triangular-Lattice Hofstadter–Hubbard Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-10-28 20:00 EDT
Yang Liu, Ya-Hui Zhang, Xue-Yang Song
A transition between an integer quantum Hall insulator and a chiral spin liquid can become critical without closing the single-electron gap, raising the question of which composite excitations govern the change in topological order. We investigate this question in the (\mathrm{SU}(3)) triangular-lattice Hofstadter–Hubbard model at one particle per site and magnetic flux (\pi/3) per triangle. Using infinite density matrix renormalization group calculations, we identify a weak-coupling integer quantum Hall phase and an interaction-driven (\mathrm{SU}(3)_1) chiral spin liquid. Near the transition, both the neutral and charge-(3e) correlation lengths increase substantially, whereas the single-electron correlation length remains short, providing evidence for a Chern–Simons–Higgs critical theory, where a gauge-invariant monopole carries the quantum numbers of a fermionic (\mathrm{SU}(3))-singlet trion. We discuss the implications for doping the system and recent experiments on doping (\nu=-2/3) fractional quantum anomalous Hall in tMoTe(_2).
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 6 figures
Water at the molecular frontier
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Mischa Bonn, Marie-Laure Bocquet, Andre Geim, Laura Fumagalli, Angelos Michaelides, Lyderic Bocquet
Much of the water that matters most - flowing through biological cells and membranes, percolating through soils and rocks, or processed by filtration and desalination technologies - is not bulk water. It is water in nano- and molecular-scale confinement or at interfaces. Nanoscale water is therefore central to many challenges of our time, from the global water crisis and the water-energy nexus to catalysis, electrochemistry, and health. Beyond its applications, nanoscale water has emerged as a rich scientific field in its own right: discoveries are accumulating rapidly, revealing that confinement and interfacial forces produce a range of behaviours absent in the bulk. Sometimes this amounts to a renormalization of bulk properties; in other cases, new and non-intuitive phenomena emerge - exotic phases, anomalous transport, and dielectric responses that defy continuum expectations. A convergence of atomically precise nanofluidic devices, novel spectroscopies and microscopy approaches, and machine-learning-accelerated simulations is now exposing the molecular mechanisms behind these behaviours. This Perspective argues that the recent findings should not be viewed as isolated nanoscale anomalies, but as evidence for a molecular regime of water in which continuum descriptions must be rethought and molecular-level understanding becomes essential. Recognising and exploring this regime should have consequences ranging from fundamental physics to the rational design of future technologies that rely on water and dissolved ions.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Fluid Dynamics (physics.flu-dyn)
perspective under review
On-the-fly Estimation of Quantum-Corrected Thermodynamics in LAMMPS
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-10-28 20:00 EDT
Robert Ramji, Ilya Mazalov, Ricardo Buarque, Alexandria Do, Xiaoxu Ruan, Tod A. Pascal
We present a native implementation of the Two/Three-Phase Thermodynamics (xPT, $ x \in {2,3}$ ) method within the LAMMPS molecular dynamics framework, termed FixXPT. xPT is an approach for obtaining absolute, quantum-corrected thermodynamics (entropy, enthalpy, free energy, heat capacity, diffusivity) from the density of states function, obtained from the velocity autocorrelation function of an equilibrium trajectory. FixXPT addresses non-trivial integration challenges, including atom reordering, compute scheduling, FFT backends, unit systems, and partitioning of atomic velocities into molecular modes. Two autocorrelators are provided: a Wiener-Khinchin FFT correlator with one cumulative window-end operation, and an in-line multi-tau correlator whose memory footprint grows only logarithmically with the window length, removing the principal scaling bottleneck for long analysis windows. The velocity history of each window is distributed across the MPI ranks, so the memory the fix adds to a node stays nearly constant as ranks are added and its cost falls with the number of GPUs. Replaying identical velocity frames through FixXPT and the stand-alone pyxPT post-processor reproduces every thermodynamic observable of well-sampled groups to within 0.1 to 0.5% across the full analysis-mode matrix; sparsely populated ionic species agree within their statistical uncertainty, and the multi-tau VACF converges monotonically to the FFT result as its buffer grows, from 0.8% to 0.1% drift across a 16-fold buffer sweep. The code is distributed as a drop-in LAMMPS package.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
The Acridine Polymorph Landscape: Characterization and Selective Control by Additives
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-10-28 20:00 EDT
Adam Lahouari, Hengyu Zhou, Nikolaos Galanakis, Michael Kilgour, Daisuke Kuroshima, Jihye Han, Bart Kahr, Mark E. Tuckerman, Alexander G. Shtukenberg, Jutta Rogal
Polymorphism in molecular crystals presents a major challenge for controlling crystallization. Here, we combine experiment and theory to characterize the polymorph landscape of acridine and investigate its selective control by additives. Melt crystallization experiments resolve the previously unknown structure of form VIII, while topological crystal structure prediction recovers all seven known unsolvated polymorphs with determined crystal structures. Combining a fine-tuned machine-learned interatomic potential with anharmonic free energy calculations reproduces the experimentally observed stability relationships and reveals a shallow free energy landscape. Finally, experimentally observed additive-induced polymorph preferences correlate with mixed-crystal substitutional defect energies and topological similarities between additive and acridine crystal structures. Together, these results provide a comprehensive picture of acridine polymorphism, linking crystal structure, thermodynamic stability, and additive-controlled crystallization.
Materials Science (cond-mat.mtrl-sci)
Mediated Interactions between Fermi Polarons in the Strongly Interacting Regime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-10-28 20:00 EDT
Renato Pessoa, S. A. Vitiello, Luis A. Peña Ardila
Mediated interactions between quasiparticles lie at the heart of Landau Fermi-liquid theory, yet their behavior in the strongly correlated regime is not fully understood. Motivated by recent experiments [Nat. Phys. 20, 68–73 (2024)], we investigate mediated interactions between quasiparticles emerging from a Fermi sea—Fermi polarons—using zero-temperature quantum Monte Carlo methods. Our main result is that the Landau interaction between polarons remains repulsive in the strongly interacting regime for any coupling strength in the polaronic branch, in contrast to the downward trend observed experimentally near resonance. Deep in the short-range universal regime, our results are insensitive to the microscopic details of the interaction potential, providing robust evidence for the sign of the ground-state induced interaction. In addition, we determine the real-space interaction between static impurities, recovering a Ruderman-Kittel-Kasuya-Yosida (RKKY)-like behavior at weak coupling and the nonperturbative Born-Oppenheimer result at strong coupling. More broadly, our results establish a microscopic benchmark for how Landau quasiparticle interactions survive beyond the perturbative regime of strongly correlated quantum matter.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
5 pages + 5 pages(supplemental material) and 5 figures