Materials Science · Cross-listed from cond-mat.soft
A Robust "Shrink-and-wrap" Piecewise Construction Transforms 3-Dimensional Mesh Structures into Mechanical Metamaterials
Fnu Braminder, Issac Varghese, Noah Kim et al. (+2 more)
Mechanical metamaterials are materials that, by virtue of their microstructural architectures, exhibit mechanical properties not often found in nature: for example, auxetic mechanical metamaterials are materials that possess a negative Poisson's ratio in response to deforming forces. However, outside of relatively simple crystalline,
lattice-based, or repeating-pattern architectures composed of mostly identical unit
cells, mechanical metamaterials like auxetics are notoriously difficult to design, particularly across all three dimensions. Here we show that, for any structure that can be decomposed into triangular or tetrahedral meshes, those structures can be subjected to a simple transformation that that creates conditions within those triangular or tetrahedral simplexes that, regardless of their individual geometries, introduces a counter-rotating polygon/polyhedron mechanism that both guarantees a negative Poisson ratio and allows locally programmable mechanical properties. We apply this "shrink-and-wrap" construction to generate mechanical metamaterials from increasingly complex 3D structures, first from simple (convex) polyhedrons; then, to designs with arbitrarily large numbers of vertices and designed using constructive solid geometry (CSG) and 3D scanning; and, ultimately to 3D objects generated from
videos captured by mobile phone camera – making potentially any object or
geometric structure designed or found in the real world transformable into a mechanical metamaterial. We show that these monolithic auxetic constructions remain readily 3D-printable via additive manufacturing techniques. We expect this piecewise approach to designing arbitrarily complex mechanical metamaterial structures can enable numerous potential applications where programmable internal reconfigurations and/or force redirection are required across and throughout their 3D geometries.
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All authors Fnu Braminder, Issac Varghese, Noah Kim, Alyssa Thomas DeCruz, Eric A. Josephs
Materials Science · Cross-listed from physics.chem-ph
ElectrolyteMD-Bench: How Well Do AI Agents Conduct Molecular Dynamics Studies across Electrolyte Solvation Regimes?
Shukai Wu, Shuo Niu, Zhaoming Xu et al. (+2 more)
AI
agents are advancing the automation of molecular dynamics (MD) research, with the potential to accelerate discovery and design of lithium-battery electrolytes. However, whether they can autonomously complete scientifically reliable electrolyte MD studies remains insufficiently evaluated. We introduce ElectrolyteMD-Bench, which unifies dilute, high-concentration, and localized high-concentration electrolytes in a comparative study across distinct solvation regimes. The
benchmark connects local coordination, ionic association, single-particle dynamics, and collective transport within one continuous research process.
Agents autonomously perform system construction, equilibration, production sampling, property analysis, and interpretation under a frozen scientific model, while deciding whether to correct errors, continue sampling, or stop. We audit each study along four dimensions: simulation validity, analysis validity, evidence integrity, and outcome calibration. Across eight model–harness configurations, all 24 system runs produced valid production trajectories, yet none of the eight studies satisfied all scientific requirements. Failures included missing analyses, incorrect physical definitions or numerical implementations, insufficient statistical support, and completion claims inconsistent with retained evidence. These results expose a gap between successful MD workflow execution and reliable scientific study completion. ElectrolyteMD-Bench therefore provides a foundational test and defines a key capability threshold that autonomous electrolyte simulation must cross to advance toward computation-first materials exploration.
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All authors Shukai Wu, Shuo Niu, Zhaoming Xu, Yan Luo, Wentao Lin
Materials Science · Cross-listed from cond-mat.mes-hall
Realization of Very High Mobility InAs Quantum Wells on InP Substrates Through Convex InAlAs Graded Buffer Optimization
Tyler Lindemann, Rojila Ghimire, Alejandro Alcaraz Ramirez et al. (+4 more)
Due to strong
spin-orbit coupling, large Landé $g$-factor, and a highly transparent interface, the two-dimensional electron gas (2DEG) in InAs
quantum wells provides an ideal platform for the exploration of topological superconductivity in hybrid
semiconductor-
superconductor heterostructures. Reduction of disorder in the
semiconductor remains a primary challenge to the disambiguation of subtle interaction effects. Here we demonstrate very high mobility InAs 2DEGs grown on insulating InP substrates. Utilizing a convex compositional grading profile in an InAlAs metamorphic buffer we demonstrate InAs
quantum wells with thickness greater than 10 nm without need of Ga-containing cladding layers. We examine structural and electrical transport properties of these
heterostructures. Advances in the design of the metamorphic InAlAs buffer result in low-temperature electron mobility exceeding $1.7\times10^6$ cm$^2$ V$^{-1}$ s$^{-1}$ at 2DEG density $\leq3.2\times10^{11}$ cm$^{-2}$, the highest value yet reported for this material system.
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All authors Tyler Lindemann, Rojila Ghimire, Alejandro Alcaraz Ramirez, Ahmad Azizimanesh, Sergei Gronin, Ray Kallaher, Michael J. Manfra
Materials Science · Cross-listed from cond-mat.str-el
Plane-Wave Photon-Fock Cavity QED-DFT: Chiral-Cavity-Induced Topology in Graphene
Yetmgeta Aklilu and Kalman Varga
We develop an explicit plane-wave (PW) $\times$
photon-Fock approach to the quantized, velocity-gauge Pauli–Fierz
Hamiltonian for periodic, first-principles calculations: because the quantized vector potential is spatially uniform, the light–matter coupling reduces to an operator-valued shift of the
crystal momentum, $K\to K+\hat{\mathbf A}/c$, and the existing plane-wave machinery of ordinary solid-state DFT is reused essentially unchanged. This PW$\times$Fock construction puts first-principles cavity QED of periodic solids on the same footing as the Fock-space coupled-cluster and configuration-interaction methods already developed for molecules, opening hitherto inaccessible systems—materials in a linear or chiral cavity, in particular—to first-principles plane-wave calculations. We illustrate the method with monolayer
graphene in linear and chiral cavities, obtaining a polarization-selective Haldane gap together with the corresponding density-of-states, real-space, and circular-dichroism optical signatures. A full Brillouin-zone Berry-
curvature calculation confirms the topological character of the chiral-cavity gap directly: the occupied
manifold carries a quantized Chern number that steps through a non-monotonic sequence, $C=1\to3\to{-1}\to1\to2\to{-1}\to1$, with two narrow, sign-reversed windows—a property of extended,
vacuum-dressed matter with no counterpart in a finite molecular system.
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Materials Science · Cross-listed from cond-mat.mes-hall
Power-law growth of shift current with superlattice period in flat Chern bands
Nianlong Zou, Cheng Xu, Ning Mao et al. (+1 more)
Quantum geometry governs a wide array of physical observables in topological
quantum materials. In its ideal limit,
quantum geometry yields exact bounds and analytical results for a growing class of observables. However, a comparable framework for the shift current remains elusive because it depends on
geometric relations between multiple bands. In this work, we show that the shift current is proportional to the cyclotron shift, the displacement of the cyclotron center induced by Landau-level mixing. This mechanism yields a universal scaling law: the integrated weight and the peak magnitude scale as $l^{i+1-n}$ and $l^{2i+1-n}$ in the
magnetic length or moiré period $l$, where $n$ is the momentum order of the
symmetry-breaking perturbation and $\Delta E \propto l^{-i}$ is the level spacing. We verify the scaling law in exactly solvable chiral-$N$ Landau levels under a uniform
magnetic field and in Schrödinger and Dirac moiré skyrmion
crystals, which capture the flat Chern bands of twisted MoTe$_2$ and twisted bilayer
graphene. For a Schrödinger flat band with a distorted skyrmion texture, the integrated weight grows linearly with the moiré period and the resonant peak grows cubically.
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All authors Nianlong Zou, Cheng Xu, Ning Mao, Yang Zhang
Materials Science
Large-Area SnS Crystals by Controlled Sn-S Chemical Vapor Deposition: Growth Optimization, Morphology, and Raman Characterization
Bilal Ahmed
Tin monosulfide (SnS) is a layered IV-VI
semiconductor with strong in-plane anisotropy and promising properties for optoelectronic and ferroic applications. However, obtaining large, continuous, and morphologically well-defined SnS
crystals remains challenging. Here, we report the growth of large-area SnS
crystals using chemical vapor deposition with separate elemental Sn and S precursors. By controlling the precursor temperatures, source positions, substrate temperature, carrier-gas flow, and hydrogen flow, we obtain SnS
crystals with lateral dimensions approaching 350 micrometers. The optimized growth occurs with the Sn source at approximately 750 degrees C, the S source at approximately 230 degrees C, and the substrate maintained near 650-680 degrees C, using Ar/H2 flow rates of 120/10 sccm. X-ray diffraction shows a dominant SnS (111) reflection with no detectable secondary crystalline tin-sulfide phase within the measurement sensitivity. Raman spectroscopy reveals six characteristic SnS
phonon modes at approximately 39.3, 48.8, 95.2, 165.0, 193.1, and 219.1 cm^-1. In particular, the low-frequency modes near 39 and 49 cm^-1 are clearly resolved with FWHM values of approximately 2.52 and 2.37 cm^-1, respectively. SEM and AFM measurements further show large continuous
crystals and a relatively smooth nanoscale surface. Growth on mica produces more regular square and rectangular flakes, with lateral dimensions approaching 300 x 300 micrometers, while
crystals grown on SiO2/Si are more frequently fractured or irregular at their edges. These results demonstrate a practical growth window for obtaining large-area SnS
crystals suitable for further optical, electrical, and device studies.
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Materials Science · Cross-listed from cond-mat.str-el
Compact representation of strongly correlated Green's functions: the MOR+EC way to explore phase space
Norman Hogan, A. F. Kemper and Carlos Mejuto-Zaera
Repeated evaluation of the single-particle Green's function (GF) across parameter space is a recurring bottleneck in many-body methods, limiting the resolution at which phase boundaries may be probed and the frequency resolution of computed spectra. We introduce MOR+EC, a framework that constructs reusable reduced-order models for computing single-particle Green's functions by combining eigenvector continuation (EC) for parameter space exploration and model order reduction (MOR) for extrapolation in frequency space. Contrary to conventional parameterized MOR, we construct these reduced-order models with a parameter-independent resolvent, further reducing the number of required full-space evaluations. Benchmarking against exact diagonalization as the impurity solver for our example case of DMFT calculations for single- and two-band models, MOR+EC reproduces the DMFT-converged impurity GF to an average relative error of $\sim10^{-4}$, with a median wall-time speedup of $16-91\times$. This accuracy and efficiency together resolve a fine-grained scan of the impurity occupation as doping is tuned and produce a high-resolution phase diagram of an orbital-selective Mott transition. The reduced-order model also reproduces real- and imaginary-frequency spectra at no additional cost in full-space evaluations. This framework applies broadly to GF-based methods requiring repeated parametric evaluation and high resolution of the frequency axis.
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Materials Science · Cross-listed from cs.LG
Leakage-Safe Machine Learning for Hydrogen Embrittlement Detection in 316L Stainless Steel: A Region-Held-Out Evaluation of Texture and Deep Features in SEM Micrographs
Muhammad Awais, Muhammad Yaseen, Abdul Shakoor et al. (+3 more)
Scanning electron microscopy (SEM) is routinely used to characterize the microstructural changes caused by hydrogen embrittlement (HE) in structural steels. Machine learning can automate this characterization, but models are often evaluated using image-level splits. When several images come from the same specimen region, such splits leak information between the training and test sets. Here, we propose a region-held-out protocol for classifying as-received (AR) and hydrogen-charged (H2) SEM micrographs of 316L stainless steel, based on Leave-One-Region-Out (LORO) cross-validation over 14 spatial regions (8 AR, 6 H2; 31 images). We compared six feature-classifier combinations built on local binary patterns (LBP), grey-level co-occurrence
matrices (GLCM), self-supervised convolutional
embeddings pretrained on 143 unlabeled SEM images, and a convolutional neural network (CNN). The simplest texture approach, LBP with a support vector machine (LBP+SVM), performed best, achieving a balanced accuracy of 0.79, H2 recall of 0.69, and H2 precision of 0.82, outperforming every deep-learning and combined-feature model. A group-level permutation test (500 permutations sampled from the 3,003 possible region-to-label assignments) yielded p = 0.008, indicating that the result cannot be explained by a chance
alignment of the region structure. Grad-CAM maps from a CNN trained on the full
dataset tended to concentrate on localized surface and grain-boundary features, where hydrogen-induced morphological changes are known to occur. Under a leakage-safe, statistically validated protocol, texture descriptors recover a hydrogen-charging signature from SEM micrographs even with few samples, and the same protocol can be extended to larger HE detection studies in other
alloy systems.
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All authors Muhammad Awais, Muhammad Yaseen, Abdul Shakoor, Niaz Ahmed Niaz, Huria Zia, Muhammad Zain Shakoor
Materials Science · Cross-listed from physics.ins-det
Fast-Neutron Scintillation with Multi-Quantum-Well 2D Perovskites
Shaun Tan, Zachary Benesh, Seong Eui Chang et al. (+4 more)
Fast-
neutron scintillators must efficiently convert
neutron energy into detectable light while enabling selectivity between
neutrons and the {\gamma}-ray background. Here, we report a synthesis strategy for layered two-dimensional (2D) lead halide perovskite scintillators with independent control of the macroscopic detector geometry and microscopic phase composition. Our synthesis approach produces mm-thick, large-area scintillators with a deliberately engineered multi-
quantum-well energy landscape, creating an effective spectral separation while retaining nanosecond emission dynamics. Our scintillators exhibit an energy resolution of 5.4% at 662 keV under 137Cs irradiation. Under deuterium-deuterium fusion
neutron irradiation, we directly demonstrate
neutron and {\gamma}-ray event separation by pulse shape discrimination, with a figure of merit of 3.51. Taken together, these results establish multi-
quantum-well 2D perovskites as a scalable materials platform that combines fast-
neutron sensitivity and selectivity within a controllable detector form factor.
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All authors Shaun Tan, Zachary Benesh, Seong Eui Chang, Shelby Elder, Haidi Jakovic, Tae-Woo Lee, Moungi G. Bawendi
Materials Science
Altermagnetism and generalised tensorial properties in the exchange multiplet framework
Paolo G. Radaelli
A representation-theoretic framework for the calculation of time-reversal-odd tensorial properties of
magnetic materials based on the Bertaut–Izyumov exchange-multiplet formalism is developed. In contrast to approaches based on distinct
magnetic point groups or
spin groups for different orientations of the
magnetic order parameter, the exchange-multiplet framework permits the order parameter to be treated as a continuous variable. It is shown that, for constant-moment collinear structures, covariance imposes a simple set of
symmetry constraints on the tensor intertwiners appearing in a Landau–Lifshitz expansion. This leads to canonical intertwiner forms that factorise the
magnetic and crystallographic parts of the tensor construction. Tensor fields can be built to retain a Cartesian representation in the physical variables while acquiring a systematic dependence on the order-parameter direction through
symmetry-adapted
polynomial bases.
Magnetic-point-group selection rules are recovered automatically for arbitrary order-parameter directions, while the framework also provides a natural separation of co-rotating (SOC-free) and non-co-rotating contributions. The approach is applicable to altermagnets and conventional antiferromagnets alike and is particularly suited to experiments and first-principles calculations in which the
magnetic order parameter can be continuously varied.
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Materials Science · Cross-listed from cond-mat.supr-con
Field-induced incipient spin-density phase stabilized inside the nematic phase of FeSe$_{1-x}$S$_x$
I. Paulescu, R. M. Abedin, J. S. Pearce et al. (+8 more)
Spin-density wave (SDW) order and superconductivity frequently compete and coexist in unconventional
superconductors, where
spin fluctuations often mediate superconducting pairing. In iron-chalcogenide
superconductors, FeSe$_{1-x}$S$_x$, SDW order has only been detected under applied pressure, while both
spin and nematic fluctuations are involved in determining their rich superconducting phase diagrams. Here, we report evidence for an incipient SDW phase, within the nematic state of FeSe$_{1-x}$S$_x$, revealed in
magnetic fields up to 68~T. Once superconductivity is quenched, we observe sharp upturns in longitudinal resistivity accompanied by anomalies in tunnel diode oscillator frequency response and torque anisotropy, consistent with a field-induced electronic order. Dominant low-frequency
quantum oscillations reveal a small reconstructed Fermi surface, consistent with a field-induced SDW order. Direct experimental comparisons with a pressure-tuned nematic, analogue, FeSe$_{0.96}$S$_{0.04}$, demonstrate that SDW phases are stabilized within the nematic phase of FeSe$_{1-x}$S$_x$ via both chemical substitution and applied pressure. These findings reveal that by weakening nematicity, the SDW orders are stabilised, which promotes the dominant superconducting pairing mechanism in iron chalcogenides.
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All authors I. Paulescu, R. M. Abedin, J. S. Pearce, W. H. Fong, Z. Zajicek, A. Morfoot, W. Knafo, O. Squire, D. Graf, A. A. Haghighirad, A. I. Coldea
Materials Science · Cross-listed from cond-mat.str-el
Angular Modulations in Magnetic Torque Induced by Phase Transitions in the Triangular Supersolid $2H$-AgNiO$_2$
John S. Pearce, Zeyu Ma, Alimamy Bangura et al. (+4 more)
Easy-axis frustrated triangular
lattice antiferromagnets provide an important playground for stabilising a wide range of exotic
magnetic phases. The delafossite $2H$-AgNiO$_2$ offers a unique model system containing a
lattice of localised ($S=1$) moments surrounded by a honeycomb of itinerant electrons. Below $T_{\rm N} =19$ K, the system exhibits collinear stripe antiferromagnetic order, whereas applied
magnetic fields induce a cascade of transitions which has been proposed to contain a
magnetic supersolid phase. In this study, we perform detailed angular and field-dependent torque measurements in static fields of up to 45~T on single
crystal samples. The angular dependence of the torque displays a sawtooth-shaped signal close to the first supersolid phase, while near $T_{\rm N}$, an unexpected additional modulation emerges. On the other hand, the field dependence of the torque indicates the presence of four field-induced anomalies which evolve in distinct ways as a function of field orientation. To understand these complex behaviours and assess the role of local moments, we employ mean-field and Monte-Carlo calculations on a minimal
spin model and construct comprehensive polar phase diagrams at different temperatures. We find that the angular dependence of the torque can be understood in terms of crossing different phase boundaries by field rotation, and we identify qualitative similarities between the experimental and theoretical polar phase diagrams. Our study highlights $2H$-AgNiO$_2$ as a rich anisotropic system that provides a robust example of how
spin supersolid orders can manifest in angle-dependent
magnetic torque.
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All authors John S. Pearce, Zeyu Ma, Alimamy Bangura, Timo Sorgel, Martin Jansen, Radu Coldea, Amalia I. Coldea
Materials Science · Cross-listed from physics.geo-ph
Shape matters: DEM investigation of geometry-controlled mechanical response in irregular rock fragments under static and dynamic loading
Athena Bahramiyarahmadi and Rick Chalaturnyk
Mechanical characterization of subsurface rock formations typically requires standardized cylindrical core specimens, which are often unavailable from fractured or unconventional reservoir sequences. This study uses a Discrete Element Method (DEM) framework calibrated to Sulphur Mountain Formation siltstone to investigate how fragment geometry governs mechanical response in irregular rock particles, which are direct analogues of drill cuttings. Nineteen specimens (18 procedurally generated irregular geometries and one reference Brazilian disk), normalized to a 10 mm bounding sphere radius, were tested under quasi-static (Brazilian-type) and dynamic (Short Impact Load
Cell) loading modes. Four mechanical outputs of failure force (Ff), apparent strength ({\sigma}f), apparent stiffness (Ka), and stiffness (E) were regressed against seven retained shape descriptors. Results show that force-based quantities are strongly controlled by the surface-area-to-volume (SA/V) ratio under static loading (Adj. R2 = 0.69), while area-normalized quantities ({\sigma}f and E) are geometrically insensitive. Dynamic loading amplifies
geometric sensitivity for failure force and introduces an independent role for surface concavity depth. These findings establish a preliminary quantitative framework for interpreting mechanical measurements from irregular rock fragments when a standardized core is unavailable.
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Materials Science · Cross-listed from cond-mat.str-el
Intrinsic anomalous Hall effect in the surface conduction regime of non-magnetic narrow-gap insulator FeSi
Yong-Cheng Pan, Hwai-Chi Lin, Li-Han Wang et al. (+6 more)
The realization of an intrinsic anomalous Hall effect (AHE) in the absence of bulk magnetism is a rare phenomenon, requiring a spontaneous breaking of the time-reversal
symmetry within the boundary states without a thermodynamic phase transition. Here, we report a robust, zero-field-hysteretic intrinsic AHE confined to the low-temperature surface-conduction regime of the prototypical narrow-gap
insulator FeSi. By systematically investigating single
crystals grown via Czochralski and chemical vapor transport methods with controlled thicknesses and surface preparations, we demonstrate that low-temperature electrical conductivity correlates with surface roughness and anti-correlates with sample thickness, confirming the emergence of surface conducting states (CSS) below $T_{\rm CSS} \simeq 55-75\text{ K}$. Meanwhile, a robust, field-hysteretic and temperature-independent anomalous Hall conductivity is found below $T_{\rm AHE}\simeq45-70\text{ K}$, implying the presence of
magnetic order in the surface conduction regime. Bulk
magnetic susceptibility and specific-heat measurements reveal no thermodynamic phase transitions, verifying that the sample interior remains a non-
magnetic insulator. Analyses of conductivity scaling and effective three-dimensional conductivity reveal the intrinsic nature of this surface-driven AHE, evidencing the presence of an emergent
magnetic order within the metallic surface of a non-
magnetic bulk
insulator. These findings establish FeSi as a compelling platform to investigate the interplay between strong electron correlations and anomalous Hall transport.
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All authors Yong-Cheng Pan, Hwai-Chi Lin, Li-Han Wang, Chia-Nung Kuo, Han-Shiuan Lin, Che-Ning Yeh, Chin-Shan Lue, Anne de Visser, Yu-Te Hsu
Materials Science
Ferromagnetic resonance and magnetic anisotropy in YbMn$_\text{6}$Sn$_\text{6}$
Philipp Schwenke, Kyle W. Fruhling, David Weffling et al. (+3 more)
The RMn$_\text{6}$Sn$_\text{6}$ (R = rare earth) family of kagome magnets exhibits a rich variety of
magnetic states and unconventional electronic and
magnetic properties. While the static
magnetic properties of these materials have been extensively investigated, their magnetization dynamics remain less explored. Here, we investigate the
magnetic anisotropy and dynamic magnetization of ferromagnetic YbMn$_\text{6}$Sn$_\text{6}$ using angle-dependent ferromagnetic resonance (FMR) spectroscopy and DC magnetization measurements. The angular dependence of FMR reveals the expected uniaxial anisotropy along the crystallographic c-axis, which is the global magnetically hard axis. In addition, we identify a pronounced twofold anisotropy within the ab-plane, which is independently confirmed by angle-dependent DC magnetization measurements. The observed uniaxial anisotropy in the ab-plane indicates a breaking of the expected sixfold rotational
symmetry in the
magnetic response that is attributed to growth induced anisotropy.
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All authors Philipp Schwenke, Kyle W. Fruhling, David Weffling, Vitaliy I. Vasyuchka, Fazel Tafti, Mathias Weiler
Materials Science
Morphological evolution of an Au crystalline domain in a nano-particle investigated by Bragg coherent diffraction imaging
Seonghyun Han, Saehyun Kang, Ouyoung Kwon et al. (+4 more)
Understanding the dynamic structural
evolution of metallic nanoparticles is crucial for tailoring their functional properties. In this study, we utilized three-dimensional coherent X-ray diffraction to investigate the morphological transformation of Au nanocrystalline domains in a multi-domain nanoparticle during in-situ annealing. By combining Bragg coherent diffraction imaging with autocorrelation function analysis, we observed a transformation from an anisotropic multi-domain configuration toward a single crystalline
equilibrium morphology. Above 600 degrees Celsius, a small subsidiary domain merged into the primary domain, which was continuously coarsened at 625 degrees Celsius, resulting in a more isotropic morphology. Finally, at 635 degrees Celsius, the low-energy {111} and {100} facets emerged, and the
crystal shape converged toward an
equilibrium truncated octahedral geometry. This work demonstrates a framework for interpreting complex domain dynamics, offering fundamental insights into domain growth and
equilibrium shape formation.
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All authors Seonghyun Han, Saehyun Kang, Ouyoung Kwon, Wonsuk Cha, Hyon Chol Kang, Chan Kim, Do Young Noh
Materials Science · Cross-listed from quant-ph
Scalable simulation of non-Markovian quantum transport by stochastic-phase bath reduction
Zhen Huang, Lin Lin and Pinchen Xie
Accurate simulations of non-Markovian
quantum transport remain limited to small systems, and a key bottleneck is that each system site requires an independent set of
quantum bath orbitals. We introduce the
Stochastic Phase
Algorithm (SPA), which replaces the independent local Gaussian baths in single-quasiparticle Holstein models by $R$ shared
quantum baths with
stochastic site-dependent phases. We prove that phase averaging reproduces the target two-point bath correlation
matrix for every $R$, while increasing $R$ systematically suppresses errors from higher-order cross-site correlations. We obtain a fixed-time $O(R^{-1})$ trace-norm error bound with a prefactor independent of system size and connectivity. This spatial compression applies directly to
unitary baths and can be combined with coupled-Lindblad spectral compression [Phys. Rev. Lett. 136, 090403 (2026)], which represents each shared environment by a very small number of coupled, damped
quantum modes fitted to its thermal bath correlation over the simulation window. Numerically, SPA converges against direct
unitary benchmarks on a $3\times3$
lattice, enables full-state-vector
quantum-bath dynamics on a $100\times100$
lattice, and, with $R=1$, closely reproduces near exact
benchmarks for
exciton populations in bacteriochlorophyll aggregates and carrier mobility in rubrene.
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Materials Science
Three-photon photoemission on metallic transition metal dichalcogenide NiTe$_{2}$
Cheng-Tien Chiang, Mukesh Singh, Yu-Jhen Chuang et al. (+6 more)
Three-
photon photoemission (3PPE) signals on NiTe$_{2}$ are observed for the first time upon ultraviolet excitations. In the energy range beyond two-
photon excitations, an energy-momentum dispersive feature is clearly identified with characteristic light polarization dependence. Based on its dispersion, spectral width, as well as intensity as a function of the parallel momentum, this dispersive 3PPE feature could be ascribed to an image potential resonance overlapping with an unoccupied Ni $4s$ -Te $4d$/$5p$ bulk band in accordance with the electronic band structure. Our results underlie higher-order non-linear photoemission on metallic transition metal dichalcogenides and facilitate future ultrafast studies of coherent electron dynamics in anisotropic, two-dimensional systems.
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All authors Cheng-Tien Chiang, Mukesh Singh, Yu-Jhen Chuang, Chia-Nung Kuo, Prabesh Bista, Yu-Chan Lin, Chen-Bin Huang, Ming-Chiang Chung, Chin Shan Lue
Materials Science
Solid-State Dealloying Enables Local Symmetry Breaking in Ternary Intermetallic Thin Films
Mizuki Ohno, Reiley Dorrian, Veronica Show et al. (+2 more)
Metastable
quantum materials often occupy narrow composition windows with local
symmetries distinct from competing
equilibrium structures. These features open pathways for realizing qualitatively new electronic properties within a similar chemical subspace while at the same time complicating their deterministic synthesis. Here we illustrate a post-growth solid-state dealloying process using epitaxial ternary thin films in the La–Ag–Ge chemical space to realize a diffraction-averaged centrosymmetric superconducting structure. The process converts polar $P6_3mc$-LaAgGe into diffraction-averaged centrosymmetric AlB$_2$-type $P6/mmm$ La-Ag-Ge through net Ag loss during annealing at 800–900 $^\circ$C. Atomic-resolution electron microscopy reveals local Ag–Ge displacements of both signs relative to the planar configuration, consistent with local inversion-
symmetry-breaking distortions. The converted films exhibit composition-dependent superconductivity with critical temperatures below 1 K and in-plane upper critical fields that exceed the weak-coupling Pauli-field estimate by a factor of approximately 6 in the thinnest superconducting films. These results establish epitaxial solid-state dealloying as a route to phase-selective synthesis of metastable phases, offering control over atomic-scale structural configurations and their interplay with emergent electronic properties.
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All authors Mizuki Ohno, Reiley Dorrian, Veronica Show, Salva Salmani-Rezaie, Joseph Falson
Materials Science
Disentangling spin polarization from driven circular ionic motion in EuTiO$_3$
Clifford J. Allington, Matthew J. Lutz, Enoch Ho et al. (+30 more)
Coherently driven circular ionic motion has been reported to produce large helicity-dependent optical responses attributed to transient magnetization. However, the microscopic nature and magnitude of this phenomenon, sometimes referred to as dynamical multiferroicity, remain strongly debated. Here, we directly study the connection between ionic circulation induced by a high-field circular terahertz (THz) drive and its effect on the
spin system of EuTiO$_3$ using X-rays. This material exhibits an optical response consistent with the putative
magnetic signal observed in related non-
magnetic materials. Furthermore, the presence of Eu$^{2+}$ ions enables the use of X-ray
magnetic circular dichroism (XMCD) to test for the creation of transient
spin polarization. Simultaneously, ultrafast X-ray diffraction (XRD) measures the circular ionic motion from which we determine the mechanical angular momentum. We find a classical ionic contribution of $3\times10^{-8}~\mu_B$ from XRD and upper limits of $0.03~\mu_B$ and $0.11~\mu_B$ from the sensitivity of XMCD at the europium $M_5$ and $L_2$ edges, probing the $4f$ and $5d$ shells of Eu$^{2+}$, respectively. These observations show that large-amplitude circular ionic motion in this system is not accompanied by a detectable
spin polarization despite the clear signature in the optical data, with the XMCD upper bounds and classical contribution differing by many orders of magnitude.
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All authors Clifford J. Allington, Matthew J. Lutz, Enoch Ho, Fabian Graf, Martina Basini, Hiroki Ueda, Michael Grimes, Alexander B. Elliott, Megan F. Biggs, Ravi Finn, Shih-Wen Huang, Merideth A. Henstridge, Matthias C. Hoffmann, Takahiro Sato, Roberto Alonso-Mori, Diling Zhu, Quynh L. Nguyen, Vincent Esposito, Jeffrey T. Babicz Jr., Elizabeth Skoropata, Biaolong Liu, Eugenio Paris, Arnau Romaguera Camps, Elia Razzoli, Roman Mankowsky, Flavio Capotondi, Nicolas Jaouen, Daniele Pergolesi, Milan Radovic, Matteo Savoini, Steven L. Johnson, Jeremy A. Johnson, Urs Staub
Materials Science
Compositionally Engineered Non-Equimolar LaCoO$_3$-Based High-Entropy Perovskites with Enhanced Thermoelectric Performance
Jitendra Kumar, David Bérardan, Diana Dragoe et al. (+2 more)
The decoupling of
phonon and electron transport remains a central challenge in the development of high-performance TE materials. Configurational-
entropy maximization is widely invoked as a design principle for decoupling
phonon and electron transport. This study investigates compositionally engineered LaCoO$_3$-based high-
entropy perovskites to determine whether thermoelectric transport can be improved by tuning cation identity and concentration rather than maximizing configurational
entropy. La$_{1-x}$Sr$_x$(CoFeMnCrNi)O$_3$ ($x=0.0$–$0.2$) and selected non-equimolar A- and B-site perovskite compositions were prepared by solid-state reaction. The obtained samples are predominantly single-phase, as confirmed by X-ray diffraction and Rietveld refinement, consistent with the calculated size-disorder parameters. Multication disorder introduces substantial mass and strain-field fluctuations that promote
phonon scattering. All samples exhibit p-type, thermally activated electrical transport consistent with adiabatic SPH. Sr substitution progressively reduces the hopping barrier and $\rho$, whereas non-equimolar B-site engineering partially recovers electrical transport while retaining low k. La$_{0.9}$Sr$_{0.1}$Co$_{0.4}$Cr$_{0.3}$Ni$_{0.1}$Fe$_{0.1}$Mn$_{0.1}$O$_3$, featuring a Co-rich and Cr-rich B-site composition, combines Co-associated mixed valence and
spin-state degeneracy that sustain a large alpha with Cr-mediated control of carrier concentration and a reduced polaron hopping barrier of 0.19eV. This composition achieves a power factor of 40–43 $\mu$W/(m K$^2$) and a $zT\sim0.072$ at 1100K, approximately 2.7 times that of its equimolar analogue. These results demonstrate that targeted cation chemistry and mass contrast, rather than configurational-
entropy maximization alone, provide an effective strategy for balancing electronic and
phonon transport in multicomponent oxide TE.
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All authors Jitendra Kumar, David Bérardan, Diana Dragoe, Nita Dragoe, Ashutosh Kumar
Materials Science
Achieving 5-angstrom-resolution diffraction contrast with an uncorrected electron probe and nanosized defect characterizations
Yao Li, Austin C. Houston, Ziang Yu et al. (+8 more)
Atomic-resolution micrographs remain limited in application due to small field of view and low numbers of recorded defects. Defect imaging with reliable statistics in transmission electron microscopy (TEM) relies heavily on diffraction contrast. However, with 200-300 kV electrons, low-
curvature Ewald sphere limits diffraction resolution at ~5 nm. Here, we imaged defects with a forbidden condition in TEM and improved the resolution in diffraction contrast from 5 to 0.5 nm. The superiority of our equal-s method is demonstrated by the discovery of a novel phase and dislocation loop structure in steels, which have not been previously reported experimentally or theoretically. Our equal-s can largely replace the classical two-beam condition for defect study.
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All authors Yao Li, Austin C. Houston, Ziang Yu, Zehui Qi, Siwei Chen, Yajie Zhao, Sung Joo Kim, Steven J. Zinkle, Gerd Duscher, Blas P. Uberuaga, Benjamin K. Derby
Materials Science
SoLiD26: A First Principles Solid-Liquid Interface Dataset for Machine-learned Interatomic Potentials
Jonas Busk, Emil J. P. Frost, Yogeshwaran Krishnan et al. (+7 more)
Machine-learned interatomic potentials (MLIPs) for solid-
liquid interfaces in advanced materials applications, e.g., electrochemistry, catalysis and corrosion, require training data that samples both
liquid environments, the solid and the interface itself. We present SoLiD26, a curated solid-
liquid interface
dataset, containing 15.4 million first-principles atomic structures with up to 576 atoms and 15 chemical elements for training and evaluating MLIPs. The structures were compiled from density functional theory (DFT) calculations performed in studies of solid-
liquid interfaces, with most configurations originating from ab initio molecular dynamics (AIMD) simulations. Each record contains atomic species, positions, simulation
cell, periodic boundary conditions, potential energy and atomic forces. SoLiD26 includes aqueous coinage metal interfaces, electrode-electrolyte systems, and selected bulk reference structures, calculated with VASP using the PBE functional and D3 dispersion corrections. We describe the data ingestion and preparation pipeline used to construct the
dataset. The application of SoLiD26 for training and evaluating MLIPs is demonstrated with a suite of MACE models on a simple training, validation and test split. The
dataset enables development and benchmarking of MLIPs for structurally and chemically heterogeneous solid-
liquid interfaces.
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All authors Jonas Busk, Emil J. P. Frost, Yogeshwaran Krishnan, Henrik H. Kristoffersen, August E. G. Mikkelsen, Xueping Qin, Xin Yang, Heine A. Hansen, Arghya Bhowmik, Tejs Vegge
Materials Science
Direct observation of the electronic structure of even-layer puckered SnTe monolayer films on graphene
Satoru Ichinokura, Shunsuke Tsuda, Kiyohisa Tanaka et al. (+1 more)
We report a direct observation of the electronic structure of monolayer SnTe on
graphene by angle-resolved photoemission spectroscopy. By combining low-energy electron diffraction, momentum microscopy, core-level spectroscopy, and first-principles calculations, we show that the observed monolayer-limit electronic structure is consistent with a puckered even-layer biatomic-layer building block rather than a nonpuckered square-flat structure. The observed band dispersion and its polarization dependence are reproduced by a puckered structure with a substrate-renormalized buckling amplitude. We further show that
graphene actively interacts with ultrathin SnTe by selecting its in-plane orientational texture, renormalizing the buckling amplitude, and modifying the local interfacial electrostatic environment in the monolayer limit. In comparison, multilayer SnTe exhibits a more ringlike momentum-space distribution, interlayer-split valence bands, and a stronger p-type character, revealing the onset of thickness
evolution from an interface-stabilized puckered ultrathin limit toward a more bulklike state.
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All authors Satoru Ichinokura, Shunsuke Tsuda, Kiyohisa Tanaka, Koichiro Yaji
Materials Science · Cross-listed from cond-mat.str-el
Asymmetric magnetoresistance in 3$d$-5$d$ based La$_{0.67}$Ca$_{0.33}$MnO$_3$/SrIrO$_3$ bilayer: The role of unidirectional anisotropy
A. G. A. Rahman, Subham Naskar, R. K. Patel et al. (+4 more)
The complex interplay between
spin-orbit coupling, magnetism, and
magnetic field at the interface of a
heterostructure consisting of ferromagnet (FM) and heavy metal (HM), often exhibit extraordinary
magnetic and electric phenomena where an in-plane Dzyaloshinskii-Moriya (DM) interaction plays a crucial role to stabilize local
spin texture in FM layer. Here, we report detailed
magnetic and magneto-transport behaviour on an epitaxially grown thin
heterostructure with 3$d$ FM La$_{0.67}$Ca$_{0.33}$MnO$_3$ (LCMO) and 5$d$ HM SrIrO$_3$ (SIO).
Magnetic measurements show an unusual development of
magnetic ordering in SrIrO3 around 42 K, which further leads to a Mn/Ir
magnetic coupling at the interface. The magnetoresistance (MR) measurements show an
evolution of its value and shape with the
magnetic state of this bilayer. While MR is negative at high temperature, it shows a positive to negative crossover with stable
magnetic ordering of LCMO, and finally the positive MR exhibits an asymmetry at low temperature with the ordering of SIO. While we ascribe this unusual MR behaviour to interface-driven varying
spin scattering between itinerant and localized electrons, our results shed a light to comprehend the complex but tunable interface behavior on charge transport in a particularly designed
heterostructure, offering valuable insights for future functional material engineering.
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All authors A. G. A. Rahman, Subham Naskar, R. K. Patel, S. Manna, Chandrani Nath, Kranti Kumar, A. K. Pramanik
Materials Science
High-Throughput Photovoltaic Screening and Spacer-Dependent Shift Current in Two-Dimensional Hybrid Perovskites
Vikrant Chaudhary, Fu Li, Yue Zhao et al. (+5 more)
High-throughput first-principles screening of structurally diverse two-dimensional hybrid organic-inorganic perovskites (2D HOIPs) provides a route to systematically explore their photovoltaic properties. Here, we develop a computational workflow with two distinct objectives: spectroscopic limited maximum efficiency (SLME) screening to identify materials with promising photovoltaic potential and nonlinear shift current calculations to characterize their bulk photovoltaic response. Applying this workflow to a curated
dataset of experimentally reported 2D HOIPs, we identify more than 25 compounds with SLME values above 25% and more than 25 compounds exhibiting shift current responses exceeding 10~$\mu$A/V$^2$. We then focus on the Pb-I-based 2D HOIPs with $n=1$ to investigate the influence of spacer chemistry on the shift current response, revealing substantial spacer-dependent variations in both its magnitude and spectral peak position. Overall, these results highlight the potential of high-throughput first-principles calculations to accelerate the discovery of experimentally relevant 2D HOIPs with promising photovoltaic properties while revealing how organic spacer chemistry influences their nonlinear shift photocurrent response.
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All authors Vikrant Chaudhary, Fu Li, Yue Zhao, José A. Márquez, Wei Xie, Claudia Draxl, Zhihua Sun, Hongbin Zhang