CMP Journal 2026-09-21
Statistics
Nature: 1
Nature Reviews Materials: 2
arXiv: 72
Research Square: 2
Nature
Chemist-aligned retrosynthesis by ensembling diverse inductive bias models
Original Paper | Cheminformatics | 2026-09-20 20:00 EDT
Krzysztof Maziarz, Guoqing Liu
(刘国庆), Felix Pultar, John Gardner, Tobias Gensch, Jean Helie, Hubert Misztela, Austin Tripp, Junren Li, Aleksei Kornev, Piotr Gaiński, Holger Hoefling, Mike Fortunato, Rishi Gupta, Andrew Baxter, Darren L. Poole, Jennifer M. Elward, Adrian Krzyzanowski, Peter Pogány, Stephen D. Pickett, Ian D. Wall, Christopher M. Bishop, Philip G. Humphreys, James A. Lumley, Mario P. Wiesenfeldt, Marwin H. S. Segler
Chemical synthesis remains a critical bottleneck in the discovery and manufacture of functional small molecules1-3. While AI-assisted synthesis planning has proliferated in recent years, a detailed understanding of its failure modes has not been achieved, and models still struggle with predicting less frequent, yet strategically critical reactions, as well as hallucinated, incorrect predictions misaligned with chemists’ expectations4-12. In this work, we analyze the failure modes of current AI models and propose RetroChimera: a frontier retrosynthesis model, built upon two newly developed components with complementary inductive biases, integrated via a novel, learning-based ensembling strategy. Through experiments across several orders of magnitude in data scale, we show RetroChimera outperforms leading baselines, demonstrating robustness outside the training data, as well as the ability to learn from very small numbers of examples per reaction class. Using both pairwise and pointwise setups, we find that organic chemists prefer predictions from RetroChimera over published reference reactions and over other AI models. Finally, we demonstrate zero-shot transfer and fine-tuning on internal datasets from two major pharmaceutical companies, showing robust generalization under distribution shift. Our work demonstrates the viability of deep learning for accurate synthesis prediction in increasingly challenging regimes.
Cheminformatics, Computational science
Nature Reviews Materials
Phase-change materials for thermal management
Review Paper | Composites | 2026-09-20 20:00 EDT
Siqi Wang
(王思齐), Xiao Chen
(陈晓), Han Han
(韩寒), Zuhao Liu
(刘祖豪), Yulong Ding, Ruqiang Zou
(邹如强), Tingxian Li
(李廷贤)
Phase-change materials (PCMs) offer a pathway for thermal management in next-generation electronic devices, renewable energy systems and sustainable buildings, owing to their high capacity to store latent heat within nearly isothermal phase transitions. However, their transition from laboratory breakthroughs to real-world deployment remains hindered by inadequate thermal conductivity, shape instability and inherent trade-offs between competing thermal metrics. In this Review, we present a multiscale design framework that spans molecular-level engineering, material-level synthesis, module-level architecture, device-level design and system-level integration, bridging fundamental science with advanced applications. We first review classifications of PCMs and the thermodynamic and kinetic criteria that govern their thermal behaviours, arguing how first-order PCMs possess an ideal thermal management capacity. Subsequently, we define the key thermal metrics that describe first-order PCMs: the phase-change temperature, energy density and power density. By examining strategies for tailoring these thermal metrics, we demonstrate how coordinated multiscale design pushes PCM-based solutions towards their theoretical limits. Then, we assess scalable strategies that merge device innovation with system integration, ensuring functional stability, safety, cost-effectiveness and ecological sustainability. We conclude by outlining promising directions, emphasizing design strategies that can accelerate next-generation PCM-based materials and devices towards net-zero energy consumption.
Composites, Energy storage, Materials for energy and catalysis, Mechanical engineering
Advances and technical challenges in mono-material plastics design for sustainability
Review Paper | Mechanical properties | 2026-09-20 20:00 EDT
Ethan C. Quinn, Maëlle T. Gace, Levi J. Hamernik, Changxia Shi, Katrina M. Knauer, Gregg T. Beckham, Eugene Y.-X. Chen
The chemical complexity of multimaterial plastic products, which are traditionally manufactured with many polymer types of different chemical composition to deliver desired lifetime performance, requires demanding processing conditions and potentially complicates end-of-life (EoL) recycling. Emerging mono-material product design, which we define as the engineering (by processing, molecular, or physical approaches, or a combination of these approaches) of a polymer derived from a single monomer or comonomer combination to achieve the performance of diverse polymer types without altering its chemical composition or speciation, drastically reduces the chemical complexity of plastics and has the potential to improve the EoL recycling of some materials. Here, we identify methods that can be applied to design mono-material polymers, including processing (orientation and crystallization), physical (homologous blending) and molecular (stereomicrostructure, topology and architecture engineering as well as monomer design) methods, all of which can be used to create mono-material products. We discuss the application of these methods to existing multimaterial products (such as multilayer films) using conventional plastics such as polyolefins, current industrial examples of mono-material products as well as emerging polymeric materials, their potential use and laboratory-scale mono-material prototypes. Overall, this Review aims to demonstrate how innovations in material design can be leveraged to achieve mono-materialization and provide insights into how this approach can improve EoL processing of plastic waste.
Mechanical properties, Polymers
arXiv
Deformation-induced amorphous complexion transitions elevate strength and ductility
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Masoud Ahmadi, Jin Qin, Gabrielle Tiphéne, Mohamed Charai, Alejandro Gómez-Pérez, Khalid Hoummada, Thomas Pardoen, Matteo Ghidelli, Hosni Idrissi
Grain boundary engineering is a major avenue for tailoring the mechanical behavior of polycrystalline materials. Grain boundary complexions, including amorphous intergranular films, are classically accessed through thermal driving forces and solute segregation. Here, we discover that plastic deformation can drive amorphous complexion transitions at room temperature in a chemically primed nanocrystalline binary CuZr alloy. High-resolution and four-dimensional scanning transmission electron microscopy reveal that the amorphous complexions preferentially emerge at incoherent twin boundaries. Spatially-resolved electron pair distribution function analysis at the atomic scale, the local-order characterization of amorphous complexions, demonstrates short-range and medium-range order gradients from crystal-templated interfaces to a metallic-glass-like core. We thus uncover a novel amorphous complexion transformation-induced plasticity mechanism that concurrently increases the yield strength, fracture strain, and tensile toughness about a factor of two relative to a designed reference material. Our findings establish mechanical deformation as a non-thermal pathway to trigger amorphous interfacial states for enhancing damage tolerance in nanostructured metals.
Materials Science (cond-mat.mtrl-sci)
Bootstrapping Disordered Quantum Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Yaprak Önder, Michael G. Scheer, Minjae Cho, Eslam Khalaf
We present a bootstrap framework that yields rigorous two-sided bounds on ground-state observables of quantum systems with quenched disorder. The key idea is to extend the operator algebra to include classical disorder variables and to encode the disorder distribution through a set of moments. The method directly bounds disorder-averaged expectation values for finite or infinite lattice systems and for arbitrary disorder distributions. In contrast to conventional approaches, we do not need to sample disorder realizations, which enables us to make thorough use of symmetries that hold only on average rather than for each disorder realization. Additionally, we show that multi-replica operators can be used to access disorder fluctuations such as the variance of an observable. We apply the method to the one-dimensional random transverse-field Ising model (RTFIM) with discrete, uniform, and Gaussian disorder, obtaining tight bounds on the disorder-averaged ground-state energy density and short-range spin-spin correlators, as well as bounds on the disorder variance of the energy density. Additionally, we show that the difference between the upper and lower bounds on the disorder-averaged ground-state energy density, which we term the bootstrap gap, can be used to map out the phase diagram of the RTFIM. The bootstrap gap is small and flat within the paramagnetic and ferromagnetic phases at weak disorder, grows upon entering the Griffiths regions, and peaks along the critical line.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn)
10 pages, 6 figures
Metallic Néel order stabilized by coupling between inequivalent Hubbard layers
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Yi-Ming Wu, Jessica Yiqi Pan, Hong Yao, Steven A. Kivelson
Inspired by recent ARPES studies on multilayer ($ n\geq3$ layers) cuprate superconductors, we use the unrestricted Hartree-Fock approximation to explore the ground-state phase diagram of two coupled, inequivalently doped square-lattice Hubbard layers. In the decoupled-layer limit, the lightly hole-doped ground state is typically an incommensurate spin-stripe state. However, with sufficiently strong interlayer coupling, stripe order is destabilized relative to a commensurate Néel-ordered metal. The resulting state exhibits a reconstructed Fermi surface with hole pockets centered at $ (\pm\pi/2,\pm\pi/2)$ that are similar in character to those seen in experiments. Our results illustrate the qualitatively new physics that can arise from interlayer coupling in multilayer cuprates.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 8 figures
Bootstrapping Classical Systems with Quenched Disorder
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Minjae Cho, Yaprak Önder, Eslam Khalaf, Michael G. Scheer
We introduce a bootstrap method for deriving bounds on disorder-averaged observables in classical statistical systems with quenched disorder. The three main ingredients of the bootstrap are the positivity of ensembles of probability measures, disorder-averaged equations of motion, and explicit expectation values of random coupling variables. Together, these ingredients lead to a linear programming problem over the space of disorder averages. By further employing the positivity of the two-replica Gram matrix, we also formulate a semidefinite programming problem that produces bounds on two-replica correlators. We demonstrate the method using two examples: the two-dimensional random site-diluted Ising model and the one-dimensional disordered contact process. For the latter example, the bootstrap bounds exhibit a region of multiple kinks that we relate to the Griffiths region, whose finite-size scaling analysis yields a typical correlation length exponent in good numerical agreement with the known value.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), High Energy Physics - Theory (hep-th)
15 pages, 9 figures
Smectic Superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
We identify a mechanism in which soft nonunitary fluctuations of the pair condensate can suppress phase coherence in a two-dimensional Rashba superconductor proximate to easy-plane ferromagnetic order. This spin polarization couples linearly to the supercurrent through a Lifshitz invariant, acting as an emergent gauge field for the superconducting $ \mathrm{U}(1)$ phase. Integrating out soft magnetic fluctuations renormalizes the effective superfluid stiffness and drives the system into a “smectic” superconducting state, characterized by a finite-momentum helical phase texture and a long-wavelength stiffness that vanishes in one direction. Consequently, vortices no longer have a logarithmically divergent energy cost, and the quasi-long-range superconducting order is destroyed at any finite temperature. Weak lattice anisotropy pins the ferromagnetic order, cutting off the smectic-like behaviour at long wavelengths and thereby restoring a finite effective stiffness. Nonetheless, near the onset of magnetic order, the enhanced magnetic susceptibility leads to a vortex-deconfined regime for arbitrarily weak magnetoelectric coupling. The results provide insight into how intertwined superconducting and easy-plane ferromagnetic orders can reshape phase coherence, with relevance to rhombohedral graphene proximitized by a transition-metal dichalcogenide substrate.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
Pressure and Proximity Tuned Twisted Bilayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
David T. S. Perkins, Joseph J. Betouras
The coupling between layered atomically-thin materials mediated by van der Waals forces allows strong electronic correlations, unique topological signatures, and non-trivial spin textures, all of which play an important role in the creation of spin-, valley-, and orbitronic devices. Here, we demonstrate that twisted bilayer graphene encapsulated by transition metal dichalcogenides exhibits a generically non-radial spin texture yet hosts a purely collinear Edelstein effect despite this lack of radial symmetry. Moreover, we show how uniaxial pressure can be used to further tune the band structure and change the number of active Fermi surfaces without compromising the collinear response. Lastly, we illustrate how the quantum geometry changes in the encapsulated twisted graphene bilayer with larger pressures spreading the Berry curvature over large regions of the moiré Brillouin zone. These results illustrate how encapsulation and pressure can be used to drastically alter the topology and spin-charge interconversion processes of moiré heterostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 5 figures
Shape Deformation and Braid Statistics of Fractional Quantum Hall Quasiparticles
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
For ``ideal anyons,’’ the Berry phase associated with a closed loop of an anyon around another is robust, that is, independent of the size or the shape of the loop, and directly yields the braid statistics. That is not the case for the fractional quantum Hall (FQH) quasiparticles (QPs), which are charged and have finite size. We consider here how the Berry phase depends on the shape of the QP, which, unlike its charge, is not a topological property and varies along the path in response to the local potential. We show that the Berry phase $ \Theta$ associated with the loop of a fractionally charged QP around another contains three distinct contributions: $ \Theta=\Theta_{\rm AB}+\Theta_{\rm shape}+\Theta_{\rm braid}$ . The Aharonov-Bohm phase $ \Theta_{\rm AB}$ is dominant, being proportional to the area of the loop, and the shape-dependent term $ \Theta_{\rm shape}$ , identified in this work, can be larger than the order-one contribution from the braid statistics $ \Theta_{\rm braid}$ . A precise determination of the braid statistics is challenging because it can be swamped by practically undetectable uncertainties in its trajectory and shape. We discuss these results in the context of the interference experiments. We also note that the fractional phase jumps in these experiments can be understood without assuming the existence of QPs with sharply quantized fractional charges at the edges of the FQH system, wherein these phase jumps are a direct measure of the fractionally quantized vorticity of the QPs in the bulk of the fractional quantum Hall state.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
53 pages, 27 figures. Comments are welcome!
Faulted loop nucleation and dopant activation in Al-implanted 4H-SiC
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Sabine Leroch, Robert Stella, Andreas Hössinger, Lado Filipovic
We present a molecular dynamics (MD) study of Al implantation in 4H-SiC to determine how implantation temperature and dose affect defect evolution and dopant activation during annealing. Simulations use the Gao-Weber potential with a Morse Al-SiC interaction reparameterized to density functional theory diffusion and kick-in/kick-out barriers. At Al concentrations above the saturation limit of ~2e20/cm3, implantation at 900 K promotes interstitial-rich planar clusters already during implantation. During annealing, these clusters trap Al and evolve into faulted interstitial loops, reducing substitutional Al incorporation. In contrast, lower implantation temperatures preserve stronger local disorder that is consumed during epitaxial regrowth, resulting in higher chemical activation within MD-accessible annealing times. Atomistic trajectories show a thermally activated transition to faulted loops once planar clusters reach about 60 interstitials. Rather than nucleating as a single coherent disk, several locally faulted regions form first and subsequently merge. The activation energy is ~1.1 eV for dislocation nucleation and ~2.1 eV for stacking-fault growth. Frank-type loops dominate at high temperature, while transient Shockley partials occur mainly at early stages and below 2000 K. As large planar defects form and dissolve, stable compensating Al-C complexes also emerge. These findings support the experimental hypothesis that secondary defects contribute to the reduced Al activation observed under supersaturation during annealing.
Materials Science (cond-mat.mtrl-sci)
Singular high-harmonic transport above a quantum threshold
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Yugo Onishi, Su-Yang Xu, Liang Fu
We show that Landau-Zener tunneling in a small-gap insulator produces a singular DC current–voltage relation, and correspondingly, strong high-harmonic generation in AC transport. Remarkably, high-harmonic responses decrease subexponentially with harmonic order, which is parametrically slower than in ordinary conductors and PN diodes. We further derive a scaling law for the current amplitude at frequency $ n\omega$ produced by the applied electric field $ E$ at fundamental frequency $ \omega$ . Our work offers a promising route to THz generation based on frequency multiplication in solids.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures + Ref and SM
Dual-Sublattice Ferromagnetism Driven by Cooperative Double Exchange and Superexchange at NdNiO$_3$/CaMnO$_3$ Interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Sharup Sheikh, Uditha M. Jayathilake, Michael Terilli, Mikhail Kareev, Jay R. Paudel, Arian Arab, Christoph Klewe, Tien-Lin Lee, Jak Chakhalian, Alexander X. Gray
Engineering emergent ferromagnetism at correlated-oxide interfaces offers a powerful route to creating collective states that do not exist in the parent materials. Here, we show that interfacial valence reconstruction in NdNiO$ _3$ /CaMnO$ _3$ superlattices generates dual-sublattice ferromagnetism involving both Mn and Ni. Depth-resolved standing-wave X-ray photoelectron spectroscopy reveals enhanced Mn$ ^{3+}$ character on the CaMnO$ _3$ side of the interface and enhanced Ni$ ^{2+}$ character on the NdNiO$ _3$ side, establishing the configurations required for Mn$ ^{4+}$ -O-Mn$ ^{3+}$ double exchange and Ni$ ^{2+}$ -O-Mn$ ^{4+}$ superexchange, respectively. At low temperature, element-specific XMCD reveals ferromagnetic responses from both sublattices, with the Ni response concentrated predominantly in the Ni$ ^{2+}$ -derived spectral component that SW-XPS independently shows to be enhanced at the interface. Together, these results show that cooperative double exchange within CaMnO$ _3$ and superexchange across the interface couple the Mn and Ni sublattices, providing a general strategy for engineering interfacial ferromagnetism in correlated oxides.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Arctic Curves and a Gapped Gas Phase in a Two-Band Free-Fermion Chain
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Charles Jordan, Dimitri M. Gangardt, Alexander G. Abanov
We study the imaginary-time evolution of a domain-wall state constrained to return to itself in a staggered free-fermion chain. The resulting space-time profile separates into frozen, liquid, and gas phases divided by sharp boundaries known as arctic curves. The spectral gap produces an incompressible half-filled gas phase bounded by an inner arctic curve, in addition to the outer frozen-liquid boundary. We determine both arctic curves, the thermodynamic return amplitude, and the complete equal-time correlation kernel. Correlations decay algebraically in the liquid regions and exponentially in the gas, while both arctic boundaries arise as caustics of free quasiparticle trajectories. The return amplitude and correlation kernel are respectively controlled by the determinant and inverse of the same block-Toeplitz operator. We obtain an exact matrix Wiener-Hopf factorization of this operator by reducing the problem to a scalar Riemann-Hilbert problem on an elliptic spectral curve. The factorization also yields the exact thermodynamic return amplitude: its logarithm consists of a quadratic term with explicit gap dependence and a bounded periodic theta-function correction. The resulting frozen-liquid-gas structure is a continuous-time free-fermion counterpart of that found in doubly periodic dimer models.
Statistical Mechanics (cond-mat.stat-mech)
50 pages, 8 figures
Functional Renormalization for Random Matrix Theory: The relational background field method
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Vincent Lahoche, Dine Ousmane Samary
The construction of a reliable renormalization group (RG) flow for discrete gravity models that preserves their underlying symmetry group, typically $ U(N)$ or $ O(N)$ , remains an open problem. For random matrix models, which are the focus of this paper, this symmetry is intrinsically tied to the interactions encoding the random geometry of two-dimensional quantum Euclidean spacetime. We develop a novel approach based on the introduction of a partial matrix-valued intermediate field. In the large-$ N$ limit, measure concentration strongly suppresses fluctuations of its singular values, allowing it to play the role of a self-consistent background field. This provides the basis for a relational RG in which the notion of scale is dynamically induced by the effective Gaussian measure in the basis where the intermediate field is diagonal. Our construction preserves the symmetry of the original model and admits a well-defined continuum limit. We show that the resulting infrared theory is described by a three-dimensional non-local Euclidean field theory with a non-trivial Wilson-Fisher-like fixed point and a single relevant direction. Remarkably, the associated critical exponent exactly matches the standard double-scaling exponent. We finally discuss extensions of the background-field approach to other discrete gravity models, such as random tensor models, and to different symmetry groups, as well as connections with more formal RG frameworks and information geometry.
Statistical Mechanics (cond-mat.stat-mech)
64 pages, 16 figures
Bend Contour Electron Tomography (BCET): Quantitative strain and topography mapping
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Henry G. Bell, Chenhang Xu, Arthur McCray, Minyong Han, Yicheng Zhuang, Harold Y. Hwang, Colin Ophus, Alfred Zong
Freestanding thin films of quantum materials naturally develop sub-micrometer, nonuniform strain fields that strongly affect their electronic, magnetic, and structural properties in both equilibrium and nonequilibrium conditions. However, current methods to quantitatively resolve these mesoscopic features are primarily restricted to scanning probes, making it challenging for dynamical measurements such as single-shot imaging and femtosecond microscopy. Here, we present a new computational framework which we denote as bend contour electron tomography (BCET), which efficiently converts bend contours in transmission electron microscope images into quantitative two-dimensional maps of strain and topography. By iteratively minimizing a designed loss function between experimental and simulated bend contour images, BCET retrieves both surface morphology and in-plane strain tensor fields without requiring scanning or diffraction mapping. We applied BCET to freestanding SrTiO$ _3$ thin films, demonstrating the successful reconstruction of the local strain distribution and curvature field with high fidelity. Our approach provides a quantitative framework for characterizing mesoscale structures in freestanding films using wide-field imaging, opening new avenues to investigate how spatial inhomogeneity governs phase transitions and nonequilibrium dynamics in two-dimensional quantum materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Mechanism of charge transfer and electrostatic field fluctuations in complex metallic alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Wai-Ga D. Ho, Wasim Raja Mondal, Swarnava Ghosh, Hanna Terletska, Ka-Ming Tam, Mariia Karabin, Markus Eisenbach, Yang Wang, Vladimir Dobrosavljević
Complex metallic alloys exhibit rich disorder-driven electronic, magnetic, and vibrational behavior arising from strong chemical disorder, leading to unconventional structure-property relationships with applications in extreme-environment materials, catalysis, spintronics, and thermoelectrics. Despite their technological relevance, the microscopic nature of charge redistribution and electrostatic fluctuations in chemically disordered alloys remains incompletely understood. Here, we develop a theoretical framework that uncovers universal statistical trends of disorder-driven charge transfer and Madelung-field fluctuations. Our analytical formalism demonstrates that local charge transfer and electrostatic potentials exhibit Gaussian-like statistics and universal linear charge-potential (qV) correlations emerging directly from the underlying disorder landscape. We identify the physical origin of these correlations in the interplay between electronic screening and impurity scattering and show how their statistical properties depend on carrier density, disorder strength, and compositional complexity. We further derive scaling relations governing qV trends across binary and multicomponent alloys, including high-entropy materials. Large-supercell density-functional theory (DFT) calculations show good quantitative agreement with the predicted statistical behavior for representative metallic alloys. Our results provide a computationally efficient framework for incorporating disorder-driven electrostatic fluctuations into effective-medium electronic-structure theories and establish a statistical-physics foundation for the predictive design of complex alloys.
Materials Science (cond-mat.mtrl-sci)
39 pages, 59 images
The effect of rolling friction on the rheology and kinematics of shear-thickening dense suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Naveen Kumar Agrawal, Michel Orsi, Martin Trulsson, Luca Brandt
Sliding friction lowers the jamming packing fraction of dense suspensions and, when activated by stress, drives non-inertial shear thickening. Additional rolling resistance lowers the jamming packing fraction further and can represent effects of particle roughness or angularity. How it changes particle motion on the approach to jamming remains unclear. Using stress-controlled two-dimensional discrete-element simulations, we compare a sliding-only suspension with systems having either uniform or surface-varying rolling friction. At fixed packing fraction, adding rolling friction changes continuous shear thickening into discontinuous shear thickening. At the same distance from the stress-dependent jamming point, $ \Delta\phi=\phi-\phi_m(\sigma)$ , however, the flow curves nearly collapse, showing that the rheological effect arises largely from the shift in $ \phi_m$ . Guided by this collapse, we compare particle kinematics in the high-stress thickened state at matched $ \Delta\phi$ , revealing differences hidden by the similar bulk response. Translational velocity correlations extend over several particle diameters, whereas rotational correlations remain local. Rolling friction promotes co-rotation at contact in place of strong counter-rotation and suppresses rotational relative to translational fluctuations. Rotation nevertheless becomes increasingly important near jamming in every case. The suspension with surface-varying rolling friction follows the behavior of a uniform system with $ \mu_r\approx0.3$ because the coefficients sampled at contacts lie well below the surface average value, here $ \mu_r\approx0.5$ . Thus, $ \Delta\phi$ largely organizes the shear-thickening rheology, but not the particle kinematics. These retain a distinct signature of the rolling constraint that must be considered when rolling friction is used to model rough or angular particles.
Soft Condensed Matter (cond-mat.soft)
Defect-mediated orientational ordering in stripe-forming magnetic systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Premarun Barik, Johan van Lierop, Robert L. Stamps
We investigate the nonequilibrium development of orientational order in a two-dimensional stripe-forming magnetic system with competing interactions. Following a quench into the stripe-ordered regime, horizontal and vertical stripes organize into orientational regions(super-domains) separated by characteristic defects. We show that the evolution towards a globally oriented stripe state is mediated by the motion and elimination of these defects, with T-junctions providing a direct microscopic measure of super-domain reorganization. The T-junction population reveals distinct dynamical regimes associated with super-domain formation, growth, and equilibration. Temperature, system size, and equilibrium stripe width modify the characteristic time scales of this evolution, while thermal fluctuations produce a finite defect population at higher temperatures. We further show that the defect dynamics observed in real space are reflected in the structure factor, providing a reciprocal-space signature of defect elimination. These results establish a microscopic defect-based description of orientational ordering in stripe-forming magnetic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Polymer-free Assembly of Unencapsulated van der Waals Heterostructure Devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Han Xuan Wong, Junjie Yu, Yuyi Yan, Adam Cronin, Felix R. Fischer
Van der Waals (vdW) heterostructures provide a versatile platform for exploring emergent quantum phenomena, yet their fabrication is often limited by interfacial contamination and incompatibility with surface-sensitive characterization. Here, we demonstrate muscovite mica as a polymer-free platform for assembling and patterning vdW heterostructure devices. Mica-mediated transfer enables clean exposed surfaces suitable for atomic-resolution scanning tunneling microscopy (STM) following mild thermal annealing, without aggressive post-processing. Mica also serves as a mechanically robust support for sequential pickup assembly, eliminating intermediate release steps. Furthermore, exfoliated mica flakes function as removable shadow masks for contact deposition, enabling straightforward patterning without conventional lithography. We quantify the temperature dependence of mica-mediated graphene pickup and demonstrate gate-dependent transport in a three-terminal graphene/hBN device fabricated using the approach. By integrating transfer, sequential assembly, and contact patterning within a single materials platform, mica provides a simple and accessible route to unencapsulated vdW heterostructures for surface-sensitive spectroscopy and quantum-device applications.
Materials Science (cond-mat.mtrl-sci)
21 pages, 4 figures
Persistence, resetting, and first-passage times of an active Ornstein–Uhlenbeck particle
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Demosthenes K. Georgiou, Paul C. Bressloff, Thibault Bertrand
We study the first-passage time statistics of an active Ornstein–Uhlenbeck particle on a finite one-dimensional interval with an absorbing boundary at one end and a reflecting boundary at the other, subject to stochastic resetting. In the weak-activity regime, we develop a perturbative solution of the Fokker–Planck equation and use a renewal framework to obtain analytical expressions for the first-passage-time distribution and its low-order moments. In the absence of resetting, activity can either increase or decrease the mean first-passage time, depending on the relation between the persistence time and the diffusive time to absorption. When resetting is introduced, we determine both the onset of beneficial resetting and the finite range of resetting rates for which resetting lowers the mean first-passage time of the active system. We further show that the resetting transition depends on the velocity resetting protocol. Finally, by comparing the active particle with resetting to the passive Brownian particle without resetting, we construct a phase diagram that identifies the regions of parameter space in which activity and resetting together reduce the mean first-passage time.
Statistical Mechanics (cond-mat.stat-mech)
21 pages, 12 figures
Analytic results for thermal correlation enhancement after a trap quench
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-21 20:00 EDT
Giorgio Li, Paola Ruggiero, Stefano Scopa
We investigate the nonequilibrium evolution of density correlations in a thermal one-dimensional Bose gas following a trap quench. We focus on the Tonks–Girardeau limit and develop an analytical description based on a finite-temperature extension of Quantum Generalized Hydrodynamics. We benchmark our predictions against exact numerics for a quench from a double well to a harmonic trap and for a trap release, and assess their temperature range of validity. Our results capture the dynamical enhancement of correlations during the expansion stages, namely the crossover from thermally suppressed to power-law bulk correlations. For the trap release, the conformal distance associated with fixed bulk points decreases as $ 1/t$ , so the correlations progressively probe a universal regime~$ \sim1/x^2$ that is independent of temperature. We thus show that, in the hydrodynamic long-time regime, the bulk density correlations approach their zero-temperature equilibrium form independently of the initial temperature.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
24 pages, 3 figures
Adaptive Mesh Coarsening for Efficient Phase-Field Fracture Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Aarosh Dahal, Abhinav Gupta, Aditya Kumar
Phase-field models provide a versatile framework for simulating fracture nucleation and propagation without explicit crack tracking. Their principal computational challenge is the need to resolve a small regularization length with a sufficiently fine finite element mesh. This requirement can render uniform-mesh simulations prohibitively expensive, particularly for three-dimensional problems, problems involving distributed crack nucleation, and soft nearly incompressible materials. Adaptive mesh refinement offers a natural means of reducing this cost, but existing approaches often rely on heuristic refinement indicators, are primarily designed for problems containing pre-existing cracks, and retain increasingly large refined regions as cracks grow in size.
This work presents an adaptive mesh coarsening framework along with adaptive mesh refinement for phase-field fracture. The coarsening strategy replaces the fractured region in the crack wake with a coarse crack band that preserves the essential mechanical behavior of a crack, making it necessary to have a refined mesh only in a small region near the tip of the growing crack. The method introduces a physics-based refinement indicator derived from the violation of the material strength surface, which is a necessary condition for fracture evolution. The indicator therefore robustly identifies regions where crack nucleation or propagation is imminent and can be applied across arbitrary materials, geometries, and loading conditions. The framework is implemented in parallel within FEniCSx; the supporting finite element codes are made available. Its generality and substantial computational benefit are demonstrated through benchmark problems involving crack propagation and nucleation under quasi-static and dynamic loading, for soft and hard materials, and for thermomechanical fracture.
Materials Science (cond-mat.mtrl-sci)
Simulation and Network Assembly Pipelines for Dynamically Bonded Soft Materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Tanner A. Wilcoxson, Tianhao Li, Tyla R. Holoman, Gaurav Mitra, Thomas M. Truskett, Glen M. Hocky
Soft materials linked by reversible covalent or supramolecular bonds form a diverse class of assemblies with promising applications from nanoscience to medicine. Experiments typically probe bulk phase behavior and rheology, but it remains difficult to measure how microscopic bonding kinetics and the mechanics of the constituent elements give rise to bulk properties. Coarse-grained molecular dynamics (MD) simulations can bridge these scales, but most simulation approaches do not control individual bond kinetics, and those that do were mostly developed for bespoke applications that do not readily generalize. Here we present pySNAP (Simulation and Network Assembly Pipelines), a modular open source Python platform that integrates tunable dynamic bonding with a workflow, template, and analysis setup, so that users can study a wide range of systems with only small changes to input files. The platform is built on the GPU-accelerated HOOMD-blue MD engine and integrates DyBond, a GPU-accelerated plugin that forms and breaks bonds consistent with an equilibrium distribution and supports bonding between multiple types of partner species. Around this core, the snap_simulate package compiles a directory of parameter files into a HOOMD-blue simulation, and the snap_workflow package orchestrates the resulting parameter sweeps across workstations and high-performance computing schedulers. We describe the theory behind simulated dynamic bonding and how to use the package, from setting up a parameter sweep to analyzing its results, and demonstrate the framework on a diverse range of dynamically bonded systems, showing that it accommodates distinct interaction mechanisms, geometries, and physical scenarios within a unified workflow, while enabling both reproduction of existing models and rapid construction of more complex composite systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
17 pages, 12 figures
Projective representation theory of spin space groups
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Zheng Zhang, Peiyuan Wang, Y. X. Zhao
Spin space groups provide the natural symmetry framework for magnetic crystals with weak spin-orbit coupling, but extracting their physical consequences requires a general theory of irreducible representations. The central difficulty is that spin space groups are represented projectively: their factor systems can render lattice translations noncommuting, induce nonsymmorphic actions in momentum space, and modify the projective structure of little cogroups. These effects lie beyond conventional space-group and double-group representation theory. Here, using Mackey’s theory of group extensions, we develop a unified constructive framework for all collinear, coplanar, and noncoplanar spin space groups, including antiunitary symmetries and general factor systems. A central technical result is a canonical decomposition of the relevant factor system $ \nu$ into a translational factor $ \sigma$ , a mixed factor $ \gamma$ coupling translations to point-group operations, and a point-group factor $ \alpha$ . This decomposition makes transparent how ordinary representation theory is modified: $ \sigma$ determines the projective translation algebra and the appropriate Brillouin zone, $ \gamma$ controls the momentum-space group action and can make it nonsymmorphic, and $ \alpha$ contributes to the factor systems of little cogroups. On this basis, we construct all projective irreducible corepresentations by induction over momentum-space orbits. The framework identifies which nonsymmorphic momentum-space symmetries can be realized by spin space groups and reveals Brillouin spaces that are compact flat manifolds rather than tori, symmetry-enforced Zak phases, reconstructed high-symmetry momenta and band degeneracies, and new types of quasiparticles. Our results establish the representation-theoretic foundation for systematic studies of weak-spin-orbit-coupled magnetic materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
29 pages
Efficient MPO Construction for Long-Range Hamiltonians with Periodic Boundary Conditions: Application to Many-Body Dynamics
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-21 20:00 EDT
Matrix product operator (MPO) serves as a fundamental component in tensor network simulations of quantum many-body dynamics. We employ an MPO construction that introduces additional propagation channels to embed both periodic boundary conditions and finite-range couplings directly into an open boundary MPO. We apply this construction within the time-dependent variational principle (TDVP) framework to simulate quench dynamics in a spin-1/2 chain with finite-range interactions, and benchmark the results numerically against the fourth-order Runge-Kutta method, finding excellent agreement for both single-body and two-body observables. The approach offers a practical route for tensor network simulations of many-body dynamics in periodic finite-range systems.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 3 figures
Granular thermostat implementation within the soft-sphere Discrete Element Method (DEM) framework, considerations and limitations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Marco Previtali, Herbert Eric Huppert, Sergio Andres Galindo Torres
Dense granular flows are commonly investigated using the soft-sphere Discrete Element Method (DEM), whereas large-scale applications generally require continuum models. Granular temperature, defined as the variance of particle velocity fluctuations, is a relevant variable to collapse rheological scaling. However, experimental forcing approaches used to control temperature also affects other aspects of the granular state.
An alternative is to use a thermostat algorithm to control the fluctuation energy directly. Although thermostat algorithms are well established in Molecular Dynamics (MD), their behaviour in dissipative DEM systems has received comparatively little attention. We show that conventional Langevin and Nosé-Hoover thermostats exhibit complementary limitations: Langevin control requires strong coupling to offset collisional dissipation, thereby damping particle dynamics, whereas Nosé-Hoover does not independently disrupt the correlations and segregation generated by repeated inelastic collisions, leading to non-ergodic and numerically unstable states.
To address these limitations, we introduce two pairwise hybrid formulations combining deterministic temperature regulation with stochastic decorrelation. Both enforce the prescribed temperature, while variation of the stochastic decorrelation timescale modifies velocity statistics and associated mesoscopic properties such as diffusivity. Finally, application to pressure-controlled simple shear shows that increasing granular temperature at fixed inertial number reduces the apparent friction, consistent with previously reported trends. The framework therefore provides controlled reference states for comparing differently forced granular systems and identifying the variables required for temperature-dependent constitutive models.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
27 pages main text, 31 with appendix, 34 with references. 14 figures. Relevant data is available at this https URL. The paper has been submitted to Physics Review Research
The Critical Role of Itinerant Contributions to Orbital Angular Momentum Relaxation and Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Andrew C. Grieder, Luis M. Canonico, Frederico Simões, Aron W. Cummings, Yuan Ping
Orbital angular momentum (OAM) is a promising degree of freedom for low-dissipation transport and magnetization control, yet its relaxation mechanisms remain controversial, with atomcentered approximations (ACA) predicting much shorter OAM diffusion lengths than experiments. We address this discrepancy using first-principles Lindbladian density-matrix dynamics, capturing electron-phonon scattering and itinerant OAM contributions, together with a first-principles parameterized tight-binding approach that separates the ACA and itinerant components. In MoS2,a strong-spin-orbit-coupling (SOC) system, orbital relaxation is multi-timescale, with fast intervalley redistribution followed by slower decay coupled to the spin. In weak-SOC silicene, spin and orbital dynamics decouple; an electric field tunes spin relaxation while leaving orbital lifetimes unchanged. In both materials, ACA orbital lifetimes are at least one order of magnitude shorter than itinerant ones, due to ultrafast precession driven by crystal-field splitting, absent from the itinerant component. These results demonstrate that going beyond atom-centered models is essential for describing orbital relaxation and diffusion.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Quantum Physics (quant-ph)
Strain-Induced Relaxor Multiferroicity at Room Temperature in Hexaferrite BaFe12O19 Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Yilin Evan Li, Harikrishnan KP, Sankalpa Hazra, Zhiren He, Jayanti Higgins, ChanJu You, Mario Brützam, Jiaqiang Yan, Anna Park, Maya Ramesh, Wenwen Zhao, Jayda Shine, David G. Mandrus, Ramamoorthy Ramesh, Ankit S. Disa, Christo Guguschev, Guru Khalsa, Craig J. Fennie, Venkatraman Gopalan, Yu-Tsun Shao, David A. Muller, Darrell G. Schlom
Multiferroic materials that combine magnetic and electric order at room temperature are rare. Here, we demonstrate strain-induced room-temperature polar order in the ferrimagnetic hexaferrite BaFe12O19. First-principles calculations reveal a strain-tunable energy landscape with multiple competing dipolar configurations and predict that compressive strain favors polar distortions. Using an isostructural Sr1.03Ga10.81Mg0.58Zr0.58O19 substrate, we grow coherently strained BaFe12O19 films with 1.1% in-plane biaxial compression. Second-harmonic generation measurements demonstrate inversion-symmetry breaking and establish a strain-stabilized polar phase that persists to at least 1000 K. Multislice electron ptychography directly reveals enhanced off-centering of Fe3+ ions within the trigonal-bipyramidal sites of the strained films and spatially varying local polarization, demonstrating the formation of polar nanoregions. Path-integral Monte Carlo simulations further show that compressive strain suppresses quantum fluctuations and stabilizes these local polar distortions. Together, these results establish strain-engineered BaFe12O19 as a room-temperature relaxor multiferroic, in which robust ferrimagnetism coexists with nanoscale polar order. Our work demonstrates a route for transforming an incipient ferroelectric ferrimagnetic into a polar magnetic material through epitaxial strain.
Materials Science (cond-mat.mtrl-sci)
Local Detailed Balance in the Lorenz Model: Replaces the Butterfly with Frenetic Bursting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Faezeh Khodabandehlou, Christian Maes
The Lorenz system is the canonical low-order model of convective instability, yet its dissipative and driving terms have never been checked against, nor constructed from, an explicit thermodynamic bookkeeping. We derive a modification that satisfies the local-detailed-balance condition for macroscopic relaxation toward nonequilibrium steady states, thereby identifying the thermodynamic force, entropy-production rate and frenesy of the resulting flow. The resulting model produces a transition from a quiescent fixed point to a robust, large-amplitude relaxation oscillation, closely analogous to recharge-discharge oscillator paradigms used for the El Nino-Southern Oscillation. The system alternates between a long, nearly reversible recharge phase and a brief, violently frenetic discharge burst, during which essentially all of the cycle’s activity and entropy production is concentrated.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD)
Rydberg excitons in core-shell nanostructures I. Optical properties
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Sylwia Zielińska-Raczyńska, Gerard Czajkowski, David Ziemkiewicz
Optical properties of Cu$ _2$ O-metal core-shell nanostructures containing Rydberg excitons are examined. Calculations of electron and hole eigenfunctions and eigenenergies are used to calculate exciton energy and its dependence on system geometry and dimensionality. The limits of very small and very large structures are discussed, making the results applicable to low principal quantum number excitons as well as to Rydberg states. The Real Density Matrix Approach method is used to calculate the optical properties of the studied systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
13 pages, 12 figures
The charge dependent hard-sphere model: Polycrystals as low-energy configurations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
We investigate the emergence of rigid polycrystalline structures in atomistic ionic particle systems as low-energy configurations. The interaction between particles of opposite charge is modeled by hard spheres that interact when they are tangential. The interaction between particles of same charge is modeled as a hard repulsion that forces a minimal distance between them. The atomistic energy is frame invariant, and no underlying reference lattice is assumed on the ionic configurations. The asymptotic behavior of configurations with finite surface energy scaling is identified by means of $ \Gamma$ -convergence. The related continuum theory is described by piecewise constant fields that encode the local orientation of the configuration. The limiting energy is local and concentrates at grain boundaries, which correspond to the boundaries of the regions where the underlying configuration has a constant orientation. The limiting energy density is anisotropic and depends on the relative misorientation of the two grains, their translation misfit, and the normal to their interface. Furthermore, we perform a fine analysis of surface energies for solid-solid and solid-vacuum phase transitions and determine energetically favorable orientation mismatches. This relies on a structure result for our grain boundaries, which shows that, due to the rigid setup, interpolating layers near the grain interface are energetically not favorable.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph)
46 pages, 12 figures
Granular structure and heterogeneous deformation preceding avalanches
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Ibrahim Awada, Michel Bornert, Vincent Langlois, Julien Léopoldès
Granular packings undergo intermittent rearrangements, known as precursors, before avalanche onset. Using grain-scale tracking in an inclined granular layer, we show experimentally that the number and recurrence of precursors change with the compatibility between the anisotropic structure inherited from preparation and the subsequent loading direction. Preparation also modifies the propagation of the mobility front, defined as the region in which the packing undergo measurable displacement: frequent precursors produce small progressive advances, whereas rare precursors involve larger extensions. By contrast, several features remain unchanged across protocols. The ensemble-averaged displacement always decays exponentially with depth over approximately four grain diameters, while the local shear-strain variance follows a common quadratic scaling with the mean strain. A two-state model suggests that, regardless of the packing structure, local strain heterogeneities affect approximately one quarter of the elementary cells, superimposed on the exponential strain profile. The reported results separate preparation-dependent precursor activity from the robust spatial features of the deformation preceding avalanches.
Soft Condensed Matter (cond-mat.soft)
Single Best Fits Can Be Misleading: Resolving Common Trapping Signatures across FA–Cs Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Maxim Simmonds, Katarzyna Pydzińska-Białek, Thomas C. Rossi, Mostafa Othman, Aïcha Hessler-Wyser, Christian Wolff, Christophe Ballif, Vincent M. Le Corre, Eva Unger
Identifying defects responsible for non-radiative recombination in metal-halide perovskites remains challenging, with no common defect signatures established across compositions. Here, we combine fluence-dependent time-resolved photoluminescence, full Shockley–Read–Hall modelling and Bayesian posterior inference across an FA$ _{1-x}$ Cs$ _x$ PbI$ _3$ compositional series. We show that trap occupation governs carrier dynamics and defect-parameter identifiability in semiconducting materials: weakly occupied states exhibit electron-capture-coefficient–trap-density degeneracies, whereas trap filling lifts them. In our perovskite systems, a non-degenerate signature $ T\beta$ , characterized by a strongly asymmetric $ \beta_p/\beta_n$ capture-coefficient ratio, occurs across all compositions, suggesting substantial trap filling is a general feature of perovskite carrier dynamics. We further identify $ T\alpha$ as a shared, device-performance-limiting non-radiative recombination channel, while a shallow $ T\epsilon$ signature unique to FAPbI$ _3$ produces the largest steady-state non-radiative recombination rate and is consistent with the previously observed high stacking-fault density of this composition. This framework therefore provides a basis for comparing trapping signatures across different semiconducting materials at room temperature.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Supporting code is in: this https URL DOI code: this https URL DOI data: this https URL
Orbital angular momentum accumulation in SrVO3 thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Julien Brehin, Montserrat X. Aguilar-Pujol, Dongwook Go, F. Casanova, J. Fontcuberta, E. Longo
Orbital transport in light transition metals has emerged as a promising route toward angular-momentum electronics, with Hanle magnetoresistance (HMR) providing a direct electrical probe of the orbital Hall effect (OHE) in non-magnetic conductors. Here we report magnetoresistance signatures consistent with orbital HMR in epitaxial SrVO$ \ast3$ (SVO), a narrow-band $ d^1$ oxide grown on (001)-oriented (LaAlO$ \ast3$ )$ \ast{0.3}$ (Sr$ \ast2$ TaAlO$ \ast6$ )$ \ast{0.7}$ substrates. In films of different thickness and longitudinal resistivity, field-dependent measurements reveal a reproducible positive, even-in-field, and approximately quadratic $ \Delta\rho\ast{x-y}$ response, as expected for HMR. Angular measurements characterize the corresponding magnetoresistance anisotropy and reveal an additional non-Hanle contribution. Density functional theory (DFT) calculations yield an intrinsic orbital Hall conductivity $ \sigma\ast{\mathrm{OH}}^{\mathrm{DFT}} = 390,(\hbar/e),\Omega^{-1}\mathrm{cm}^{-1}$ and a spin Hall conductivity $ \sigma_{\mathrm{SH}}^{\mathrm{DFT}} = -12,(\hbar/e),\Omega^{-1}\mathrm{cm}^{-1}$ at the Fermi level, corresponding to $ |\sigma_{\mathrm{OH}}^{\mathrm{DFT}}/\sigma_{\mathrm{SH}}^{\mathrm{DFT}}| \approx 33$ , thus indicating a predominantly orbital response. Using the diffusive HMR framework with $ \lambda_{\mathrm{OD}} = 2$ nm as a reference value, the 20.8 nm film gives conservative saturation-limit lower-bound (LB) estimates $ \theta_{\mathrm{OH,LB}} = 0.0144 \pm 0.0004$ and $ \sigma_{\mathrm{OH,LB}} = (460 \pm 11),(\hbar/e),\Omega^{-1}\mathrm{cm}^{-1}$ , comparable to the DFT value. Across the series, lower-bound estimates obtained with the same $ \lambda_{\mathrm{OD}}$ increase overall with longitudinal conductivity. These results suggest that narrow-band $ d^1$ metallic oxides are a promising platform for orbital transport.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 5 Figures
Phase Separation in a system of Brownian inertial rotors
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Lucio Mauro Carenza, Pasquale Digregorio, Massimiliano Semeraro, Antonio Suma, Ignacio Pagonabarraga, Giuseppe Gonnella
We uncover an emergent phase separation in a system of inertial dumbbells put into persistent rotation by a constant applied torque, breaking chiral symmetry, while interacting with each other through repulsive hard-core interactions. We numerically determine the phase diagram of the model, showing that there exists a binodal and a spinodal region where the system separates into a dense liquid and an ordered phase, which we identify as hexatic. An analysis of the system pressure unveils that the mechanism underlying the phase separation is heavily controlled by inertia. Locally injected kinetic energy is steadily stored into the system in a way that depends on density and that, at large inertia, results in a hot dilute and cool dense state, leading to a generically unstable homogeneous phase. The interplay between dumbbells’ arrangement into clusters and chiral forces produces a spontaneous rigid rotation of the clusters around their centers of mass.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
8 pages, 8 figures
Validation of an Ab Initio-Informed Electronic Stopping Model for Large-Scale Atomistic Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Glen P. Kiely, Rafael Nuñez-Palacio, Andrea E. Sand
Accurately modeling nonadiabatic electronic energy dissipation in atomistic simulations of radiation damage remains a key challenge. Existing models often rely on arbitrary thresholds and neglect trajectory-dependent, band-structure, and nonlinear effects. A model developed by Tamm \textit{et al.} (\href{this https URL}{doi:https://doi.org/10.1103/PhysRevLett.120.185501}) offers a nonempirical description of electronic dissipation for atomistic simulations, but has not been directly benchmarked in the electronic stopping regime. We present the first such benchmark via the comparison of atomistic simulations with experimental ion transmission experiments. The model accurately captures the magnitude and trajectory-dependence of the predicted energy losses. These results support the reliability of the model for predictive large-scale atomistic simulations of radiation cascades.
Materials Science (cond-mat.mtrl-sci)
Tunable parametric vibrations in fluid ferroelectric fibres
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Alexander Dieter-Jarosik, Hajnalka Nádasi, Rachel Tuffin, Melanie Klasen-Memmer, Alexey Eremin
Freely suspended ferroelectric-nematic fibres combine 1D fluidity with macroscopic spontaneous polarisation. Under alternating electric fields, we observe a sequence of dynamical states, from subthreshold pulsations to polarity-dependent axial flow, and sustained transverse oscillations. We show that the oscillatory state arises from a parametric instability of a liquid string whose effective tension is dominated by the electrical polarisation-field coupling contribution. A Floquet model incorporating finite-time polarisation switching captures the observed resonance tongues, modal selection, and square-wave response. These results establish ferroelectric-nematic fibres as electrically programmable fluid resonators coupling polar order and interfacial flow with nonlinear vibration.
Soft Condensed Matter (cond-mat.soft)
Floquet-spin-orbit compensation and flat- and quadratic-band contact in the $α$-$T_3$ lattice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Imtiaz Khan, Muzamil Shah, Reza Asgari, Gao Xianlong
We investigate Floquet–spin-orbit compensation in the three-band $ \alpha$ -$ T_3$ system, which interpolates between graphene at $ \alpha=0$ and the dice lattice at $ \alpha=1$ . By tuning the interplay between an off-resonant circularly polarized optical field and intrinsic spin–orbit coupling, we identify three distinct pairwise band-degeneracy conditions in the quasienergy spectrum: (i) valley–spin degeneracy, (ii) spin–band degeneracy, and (iii) flat–dispersive band degeneracy. The flat band is not an artifact of a two-band reduction but rather an exact property of the continuum Hamiltonian at this compensation point, where the complete three-band Hamiltonian supports a momentum-independent dark state. A winding-two low-energy Hamiltonian and a finite-momentum Berry-curvature maximum, whose radius scales as the square root of the detuning, emerge from detuning this contact. We further show that the intrinsic transverse thermoelectric response encodes these spectrum patterns. The flat- and quadratic-band degeneracy can be predicted for $ 0<\alpha<1/2$ because the two response scales linked to the linear contacts have a monotonic ratio independent of the common spin–orbit energy scale. This allows an inverse determination of $ \alpha$ and of the common spectral scale. The analytical results are confirmed by full three-band Kubo calculations, which also define the regime in which this inverse characterization is still observable. These results connect an experimentally accessible, Berry-curvature-sensitive thermoelectric response to tunable Floquet–spin–orbit band geometry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
19 pages, 7 figures
Transport statistics and thermoelectric performance of Hofstadters butterfly
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Friedemann Queißer, Gernot Schaller
We investigate electrons subject to a magnetic field that may tunnel along a square lattice and additionally to two electronic leads. Using non-equilibrium Greens functions we evaluate the transmission and from that particle and energy currents and zero-frequency noise of the setup. We identify sweet spots for which the transmission reaches unity over broad frequency windows – carried by topologically protected boundary modes that are quite robust against local fluctuations of on-site energies. These transmission plateaus can be exploited for the implementation robust current standards, clocks and thermoelectric devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
8+3+2 pages, 7 figures
Digital-analog concept for superconducting perceptron-like neural networks
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Andrey E. Schegolev (1,2), Vsevolod I. Ruzhickiy (1,2), Georgy I. Gubochkin (2,3), Alexander S. Ionin (3), Ivan A. Nazhestkin (3), Mikhail Y. Fominskii (4), Lyudmila V. Filippenko (4), Igor I. Soloviev (1), Maxim V. Tereshonok (2), Nikolay V. Klenov (2) ((1) Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, (2) Moscow Technical University of Communications and Informatics (MTUCI), (3) Superconducting Quantum Computing Lab, Quantum Center, (4) Laboratory of superconducting devices for signal detection and processing, Kotelnikov Institute of Radioengineering and Electronics)
A promising route to superconducting artificial neural networks is a hybrid digital-Analog architecture that combines digital single-flux-quantum (SFQ) communication with compact Analog nonlinear processing. The study focused on the dynamic conversion of a discrete signal passing through a digital-to-Analog-to-digital (DAD) converter, in which the role of the Analog cell was performed by a $ \Sigma$ -neuron with a nonlinear transfer function – the basic cell of perceptron-like neural networks. Furthermore, the DAD converter, the elementary functional block of the hybrid architecture, combines a digital-to-analog converter (DAC) and an Analog-to-digital converter (ADC), and re-encodes the Analog $ \Sigma$ -neuron waveforms as an SFQ pulse sequence. Circuit-level simulations demonstrate how input values encoded by SFQ pulse trains are converted into analog signal levels, transformed by the $ \Sigma$ -neuron, and mapped back to pulse-based outputs. As a key experimental step, we fabricated and characterised a redesigned $ \Sigma$ -neuron and measured a sigmoid-like transfer characteristic suitable for activation-function implementation. The extracted response was incorporated into system-level simulations to assess the influence of realistic device parameters on the conversion process. We delineate the operating-range matching requirements for the DAC, neuron, and ADC blocks, supporting the feasibility of the proposed interface as a building block for perceptron-like superconducting neural networks with digital inputs and outputs. Finally, we developed two perceptron networks, one using a mathematical sigmoid activation and the other the measured $ \Sigma$ -neuron transfer characteristic, which reached classification accuracies of $ 97.0%$ and $ 91.9%$ , respectively, on the MNIST handwritten digit dataset.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Resonant spin mode from retarded relaxation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
In ultrafast spin dynamics additional modes in the THz range appear which cannot be captured by conventional Landau-Lifshitz equations. Extending these equations by further time derivatives (inertial Landau-Lifshitz-Gilbert equation) solves the issue only partly. Here we suggest to explain these modes by retarded Lindbladian relaxation. In spite of the simplicity of this phenomenological approach the agreement with the experimental data is promising: physically plausible parameters describe the position and the large width of these resonances. The salient feature of several almost equidistant resonance peaks is in-line with experimental evidence as well.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages with 8 figures
Spatially resolved quantum magnetometry and stray-field reconstruction of permalloy microdisks using boron-vacancy centers in hexagonal boron nitride
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Peiting Wen, Shuyu Wen, Jiang Qu, Zeling Xiong, Katrin Schultheiss, Slawomir Prucnal, Artur Erbe, Kenji Watanabe, Takashi Taniguchi, Jürgen Lindner, Jürgen Fassbender, Manfred Helm, Shengqiang Zhou, Ruslan Salikhov, Helmut Schultheiss, Yonder Berencén
Transferable hexagonal boron nitride (hBN) hosting negatively charged boron-vacancy (VB$ ^{-}$ ) spin defects offers a versatile platform for integrated quantum magnetometry, yet quantitative imaging of magnetic microstructures remains challenging. Here, we integrate a transferred hBN flake with a 4 $ \mu$ m-diameter permalloy (Py = Ni$ {81}$ Fe$ {19}$ ) microdisk and perform spatially resolved optically detected magnetic resonance measurements at room temperature. An applied in-plane magnetic field distorts the vortex-state magnetization, generating edge-localized magnetic surface charges and pronounced stray-field signatures at opposite disk edges. By referencing each pixel to its local zero-field splitting and correcting for a residual out-of-plane bias field, we quantitatively reconstruct the out-of-plane stray-field distribution, revealing peak fields of approximately 11.2 mT. An edge-charge model reproduces the spatial distribution and amplitude of the reconstructed field, linking the ODMR response to the field-driven evolution of the vortex state. These results establish transferred hBN VB$ ^{-}$ sensors for quantitative magnetometry of magnetic microstructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
20 pages, 4 Fgures
Reformulating Pfaffian Quantum Monte Carlo with the Hybrid Monte Carlo formalism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Thomas Hauschild, Lin Wang, Finn L. Temmen, Thomas Luu
Pfaffian quantum Monte Carlo extends auxiliary field methods to anomalous fermionic Hamiltonians, opening access to pairing systems and Hubbard-Stratonovich decompositions that are unavailable in determinant formulations. We show that this flexibility can be combined with the global updates of Hybrid Monte Carlo (HMC), leading to an algorithm scaling as $ \mathcal{O}(N_\tau L^3)$ , similar to its determinant quantum Monte Carlo (DQMC) counterpart without pseudofermions. The central observation is that the molecular dynamics force depends only on the magnitude of the Pfaffian weight, which admits a determinant representation and leads to a simplified force expression. This construction also yields unequal-time Majorana correlators at essentially no additional cost. For interaction kernels with no convenient analytic exponential derivative, we employ a truncated force expansion whose errors are removed by the exact Metropolis accept-reject step. Applied to the interacting Kitaev chain, the method agrees with exact diagonalization and resolves low-energy modes localized at opposite boundaries, together with their increasing overlap near the topological transition. These results establish HMC as an efficient sampling framework for Pfaffian auxiliary-field simulations.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures, The 43rd International Symposium on Lattice Field Theory (Lattice 2026)
Material chemical compositon impacts on the band alignments: Preliminary results on the 3D/2D perovskite interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Philippe Baranek (IPVF)
While hybrid organic-inorganic halide perovskite solar cells have achieved remarkable certified efficiencies, their widespread industrial and societal adoption is hindered by instabilities against light, heat, and moisture. A strategy to mitigate issues, such as moisture sensitivity, involves depositing 2D perovskites on 3D thin films for passivation, but their precise impact on cell performance requires detailed understanding. This work employs atomistic first-principles simulation, based on hybrid functionals, to investigate the structural and electronic properties of 2D/3D interfaces. Specifically, it focuses on interfaces formed by (PEA)2PbI4 (PEA = C6H5CH2CH2NH3, as 2D perovskite) and complex 3D perovskites (Cs0.125MA0.14FA0.735Pb(I0.87Br0.13)3, with MA = CH3NH3 and FA = CH(NH2)2) which are ones of the most used perovskites. The approach is based on optimized hybrid functional methods to consistently determine work function (WF), electron affinity (___), and band offset (EBO) across different layers. Preliminary results demonstrate that WF are strongly dependent on the cleavage and chemical nature of the surfaces. Furthermore, the creation of interfaces significantly impacts macroscopic potential, with a noticeable slope linked to the polarization of the 3D materials due to ionic substitutions. The band alignment is also highly sensitive to the termination and chemical nature of the perovskites, with valence and conduction EBOs varying from 0.2 to 0.7 eV and of approximately 0.25 eV, respectively. This ongoing work aims to provide a systematic description of these effects, with further investigation into the impact of dimensionality loss on perovskite stability.
Materials Science (cond-mat.mtrl-sci)
43rd European Photovoltaic Solar Energy Conference and Exhibition - EUPVSEC 2026, Sep 2026, Rotterdam (NL), Netherlands
Orbital character and photoemission signatures of the A-pocket in infinite-layer nickelates
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Leonard M. Verhoff, Michael Seidl, Liang Si, Karsten Held
The orbital character of the so-called $ A$ -pocket in infinite-layer nickelates remains under debate. We investigate bulk NdNiO$ 2$ using density-functional theory combined with dynamical mean-field theory and identify the $ A$ -pocket as a strongly hybridized state with substantial interstitial-$ s$ , Nd-$ d{xy}$ and Ni-d_$ {xz/yz}$ contributions. Our angle-resolved photoemission spectroscopy simulations reproduce the main polarization-dependent features measured experimentally. Removing the interstitial-$ s$ matrix element leads to a clear disagreement with the measured Fermi surface maps, even though the interstitial-$ s$ contribution is not dominant. Suppressing instead the Nd-d$ _{xy}$ or Ni-$ _{dxz/yz}$ matrix elements leaves the maps almost unchanged, because these are small at the zone corner. More generally, our results demonstrate that assigning the microscopic origin of spectral features in infinite-layer nickelates requires treating orbital hybridizations and photoemission matrix elements together.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Field-free and Sub-ns Magnetization Reversal in Synthetic Anti-ferromagnets using Sequential Spin-Orbit Torque and Spin-Transfer Torque Pulses
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Single free-layer Magnetic Tunnel Junctions (MTJs) with a perpendicular easy axis driven by spin currents have demonstrated fast, deterministic switching, non-volatility, and low-power memory capabilities when integrated with modern nanoelectronic devices. In this article, we numerically investigate sub-ns and field-free switching characteristics of a p-MTJ with a Synthetic Antiferromagnet (SAF) based free layer structure using sequential sub-ns current pulses of Spin Orbit Torque (SOT) and Spin Transfer Torque (STT). While the SOT pulse applied to one layer decreases the transition time by bringing the coupled layers into an in-plane configuration, the subsequent STT pulse on the system determines the switching direction. Various pulse protocols have been investigated for both SOT and STT current amplitude and pulse widths, while also considering the effect of the Reference Layer (RL). While significant regions of deterministic switching events are observed, limitations in SOT, STT parameters are further investigated in presence of thermal fluctuations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 9 figures
Adsorption of Phosgene Gas on Pristine and Noble Metal-Doped B12N12 Nanocages: Insights from Density Functional Theory
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Shahariar Chowdhury, Mohammad Abdul Matin, Samiran Bhattacharjee, Ishtiaque M. Syed
This study examines phosgene (COCl2) adsorption on pristine and noble metal-doped (Ag, Au, Pd, Pt) B12N12 nanocages using dispersion-corrected density functional theory [B3LYP-D3(BJ)]. Boron-site substitution narrows the HOMO-LUMO gap far more than nitrogen-site substitution (69-82% vs 41-67%) and was adopted throughout. All systems were fully optimized; multiple starting geometries converged to two stable minima per dopant, X-O and X-Cl. Pristine B12N12 binds phosgene weakly (Eads = -12.8 to -24.9 kJ mol^-1). Doping strengthens binding, spanning -14.0 to -60.7 kJ mol^-1 after counterpoise correction, with platinum exhibiting the highest affinity and structural stability. Natural population analysis indicates phosgene donates at most 0.33 e, and QTAIM classifies all cage-adsorbate bond critical points as closed-shell or intermediate, confirming physisorption. Vibrational frequency analysis confirms all structures as true minima and reveals that the adsorption entropy penalty (59-161 J mol^-1 K^-1) is decisive. Under Grimme’s quasi-harmonic approximation, pristine cages fail to bind phosgene (Delta G = +23.8 to +27.9 kJ mol^-1), whereas only Pt-O (Delta G = -8.8 kJ mol^-1) and Pd-O (-7.2 kJ mol^-1) adsorb phosgene spontaneously at 298 K. Transition-state theory indicates rapid room-temperature recovery (tau = 43 ms for Pt-O), while thermodynamic desorption occurs at 69.6 deg C, ensuring a practical regeneration window. Silver-doped cages provide narrow post-adsorption gaps and high electrophilicity but cannot retain phosgene at ambient conditions. Platinum doping is therefore the most effective strategy for reversible phosgene detection using B12N12 nanocages.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Keywords: Density functional theory, B12N12 nanocages, Transition metal doping, Phosgene gas sensing, Adsorption
Self-avoiding trails in two and three dimensions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Xiaodi Su, Zongzheng Zhou, Qianqian Wu
The self-avoiding trail is an important variant of the self-avoiding walk. In this work, we employ an irreversible Markov chain Monte Carlo algorithm, together with the reversible Berretti-Sokal algorithm for comparison, to simulate self-avoiding trails on the square and simple cubic lattices with periodic boundary conditions. Based on finite-size analyses of the unwrapped end-to-end distance and the Binder ratio, we accurately estimate the critical points on the simple cubic and square lattices to be 0.206,376,9(2) and 0.367,561,1(1), respectively, improving the precision of previous best estimates by factors of 500 and 70. At the estimated critical point of the simple cubic lattice, we numerically demonstrate that both the critical scaling behaviors of various quantities and the length distributions of self-avoiding trails and walks are consistent with each other. Our accurate numerical results are attributed to the efficiency of the irreversible algorithm, whose advantage over the reversible algorithm is even more pronounced for the self-avoiding trail model than for the self-avoiding walk model.
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 8 figures
Collective excitation-mediated transport in nanoscale Josephson junctions that exhibit quantum confinement
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Zhengyuan Liu, Sebastian Scherb, Werner M.J. van Weerdenburg, Daniel Wegner, Nadine Hauptmann, Alexander A. Khajetoorians
Quantum confinement can strongly modify transport through Josephson junctions. Here, we study local tunneling transport through nanoscale Josephson junction stacks in the Coulomb blockade regime, where the metallic layers exhibit strong vertical quantum confinement. We find that quasiparticle transport is strongly enhanced by a collective excitation mode intrinsic to the junction and localized in the isolated metallic overlayer. We quantify both the collective-mode energy and the Coulomb gap and show that both exhibit strong layer-dependent modulation, consistent with the modulation of the underlying quantum well states. We further investigate how the collective excitation responds to various perturbations, including mechanical motion and an applied magnetic field. Our results suggest that this collective mode is sensitive to quasiparticles near the Fermi level and may therefore provide an indirect probe of the superconducting state.
Superconductivity (cond-mat.supr-con)
Universal Dzyaloshinski-Moriya interaction dictates pairing in unconventional superconductor families
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Baishun Yang, Yida Chu, Xuelei Sui, Haiqing Lin, Shijie Hu, Bing Huang
The collinear-antiferromagnetic spin-fluctuation paradigm has long guided unconventional superconductivity research, yet fails to reconcile the noncollinear spin phenomena observed across cuprates, iron-based superconductors, and nickelates. Using extensive first-principles calculations and unbiased large-scale DMRG simulations, we show that Dzyaloshinski-Moriya interaction (DMI)-arising from local inversion-symmetry breaking-is a common ingredient across these families. This DMI unifies hallmark observations in parent compounds-incommensurate orders, spin-wave gaps, and noncollinear textures. Under hole doping, strong DMI drives spin vortices to merge with pi-shifted hole stripes, forming hybrid vortex-hole stripe phases. These phases stabilize charge order while supporting, not suppressing, superconductivity. By contrast, under electron doping, these vortices pin holes and suppress long-range superconductivity. Our results establish DMI as a unifying link between noncollinear magnetism and superconductivity, identifying hole-strip-vortex coupling as a microscopic pairing engine. Given that DMI is common across major superconductor families, these findings challenge the prevailing pairing mechanism and offer an experimentally testable roadmap for materials optimization.
Superconductivity (cond-mat.supr-con), Computational Physics (physics.comp-ph)
18 pages, 5 figures
Impact of exciton-phonon and exciton-magnon interaction on transport in anisotropic 2D magnetic semiconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Daniel Erkensten, Katarzyna Sadecka, Marie-Christin Heißenbüttel, Thorsten Deilmann, Ermin Malic
Two-dimensional magnetic semiconductors provide a unique platform for exploring the interplay between charge, lattice, spin, and light. The strong Coulomb interaction combined with long-range magnetic order enables efficient coupling between excitons and both lattice vibrations and spin excitations, thereby strongly influencing exciton dynamics and transport in these materials. Here, we develop a microscopic many-body theory of exciton–phonon and exciton–magnon interactions in mono- and bilayer CrSBr. We demonstrate that the quasi-one-dimensional character of excitons in CrSBr gives rise to strongly anisotropic exciton–phonon and exciton–magnon scattering, resulting in direction-dependent diffusion coefficients. Furthermore, we identify a distinct temperature dependence originating from one-phonon and two-magnon scattering processes, providing characteristic signatures of the underlying microscopic interactions. Our work establishes a microscopic framework for understanding exciton transport in magnetic van der Waals semiconductors and provides guidance for future optical spectroscopy and exciton transport experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 6 figures
Full macroscopic thermalization and the formation of Schrödinger’s cats by unitary time evolution in the weakly perturbed Ising model - Applications of the Roos-Sugimoto-Teufel-Tumulka-Vogel theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
We study macroscopic thermalization in the ferromagnetic Ising model with a weak generic (highly nonlocal and many-body) random quantum perturbation. We prove that a single typical perturbation makes every initial state $ |\Phi(0)\rangle$ in a specified energy shell thermalize: a measurement of a large class of macroscopic observables in the time-evolved state $ |\Phi(t)\rangle=e^{-i\widetilde H_Lt}|\Phi(0)\rangle$ yields their thermal equilibrium values, within a prescribed precision and with overwhelming probability, at sufficiently large, typical times $ t$ . The result covers the full finite-temperature range, including the ordered phase, where we use plus boundary conditions. With periodic boundary conditions in the ordered phase, every energy eigenstate in the shell is shown to be an almost balanced macroscopic Schrödinger-cat state. Moreover, every pure initial state becomes such a cat at sufficiently large, typical times, with each branch in the corresponding macroscopic thermal equilibrium. The proof combines the theory of Roos, Sugimoto, Teufel, Tumulka, and Vogel with rigorous Ising large-deviation estimates.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
18 pages, no figures. Substantially extended version of arXiv:2409.09395, including results for the full temperature range and higher dimensions, a growing family of macroscopic observables, and the dynamical formation of balanced Schrödinger-cat states
Complete Neural Electronic Initialization Accelerates Materials DFT
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Felix Ærtebjerg, Jonas Elsborg, Arghya Bhowmik
We present the first complete machine learning method for accelerating plane-wave density functional theory (DFT) in materials under the projector augmented wave (PAW) formalism. We formalize seven criteria that a \textit{Complete Neural Electronic Initializer} must satisfy for practical end-to-end PAW DFT acceleration. Applying these criteria to prior work reveals two missing structure-dependent components, augmentation occupancies and spin initialization, that prevent existing methods from providing complete reference-free initialization. Controlled ablations show that omitting these components can eliminate or reverse the acceleration obtained via models that only predict the smooth valence density. We satisfy these missing requirements by introducing AugNet, the first general equivariant model for PAW augmentation occupancies, and the first general spin density model for materials, which predicts the smooth spin-difference density and spin-difference PAW augmentation occupancies using predicted magnetic moments to constrain the global magnetic state. Combined with existing valence density models, these components satisfy all seven criteria and form a fully reference-free electronic initializer for materials DFT, requiring no electronic quantities from a converged target calculation. Our method reduces end-to-end DFT wall time by up to ~25% on unseen structures while preserving converged energies.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
34 pages, 4 figures, 15 tables
Electrodeposited Co and Ni Hexacyanoferrates: Insights into Structure and Morphology
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady, Falk Röder, Axel Lubk, Daniel Wolfmand Christian K. Müller
Prussian blue (PB) and its analogues (PBAs) are interesting materials for electrochemical applications due to their tunable redox chemistry and open framework structure. In this study, hexacyanoferrates (HCF) containing iron (FeHCF), cobalt (CoHCF) and nickel (NiHCF) were synthesized via potentiostatic electrodeposition. Cyclic voltammetry revealed distinct redox behaviors. Morphological characterization (SEM, EDX) demonstrated uniform, pyramidal film growth for FeHCF and CoHCF. Otherwise, NiHCF presented a cracked film with cubic clusters on top due to residual stress. Despite this, homogeneous element distribution was found for all samples. Structural characterization (TEM and XRD) confirmed a cubic lattice crystal structure for all films, with systematic lattice contraction from Fe to Co to Ni due to decreasing atomic radius. Raman and XPS data revealed a shift toward Fe2+ dominant oxidation states and modifications in CN bonding with the influence of K+ and water occupancy in the PBAs framework. These findings illustrate how metal substitution and deposition parameters can tune the structural and electrochemical properties of PBA films, presenting a strategic route to design tailored electrodes.
Materials Science (cond-mat.mtrl-sci)
Multivalley 3D Electronic Structure of PbSe from Soft-X-Ray ARPES and First-Principles Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Zefeng Cai, Valentine V. Volobuev, Jędrzej Korczak, Enrico Della Valle, Hantian Liu, Moritz Hoesch, Sergey M. Frolov, Tomasz Story, Vladimir N. Strocov, Noa Marom
PbSe is a narrow-gap IV-VI semiconductor, whose multivalley valence bands, with maxima at the L, $ \Sigma$ , and $ \Delta$ points, underpin its intermediate-temperature thermoelectric properties. We combine soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) with first principles simulations to study the valence band structure of bulk PbSe. High resolution measurements are conducted at photon energies of 400-900 eV to map the valence manifold along X$ \Gamma$ X, WXW, and K$ \Gamma$ K, and iso-energy surfaces are collected in the $ k_z=0$ plane. Comparison to ARPES enables a rigorous assessment of the performance of density functional theory (DFT), using semi-local and hybrid functionals, as well as many-body perturbation theory within the quasiparticle self-consistent $ GW$ approximation. We find that the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional and QP$ GW$ reproduce the measured band dispersions to within 0.1-0.2 eV over the entire valence band. In contrast, the semi-local Perdew-Burke-Ernzerhof (PBE) functional compresses the band width and deviates from experiment by up to 0.6 eV. We further show that an accurate band structure and band gap are vital to obtaining a correct description of the dependence of the Seebeck coefficient of p-type PbSe on the hole concentration (Pisarenko relation). This has implications for computational efforts to discover thermoelectric materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Topological properties and gap structure of the paired state in twisted TMD bilayers within a two-band effective model
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
We present a theoretical study motivated by the recent experimental results which demonstrate superconductivity emerging from flat topological bands of twisted transition metal dichalcogenide (TMD) bilayers. To capture the non-trivial band topology of the system, we employ an effective two-band Kane-Mele-like model and substitute it with Coulomb repulsion and inter-site pairing interactions treated at the Hartree-Fock mean-field level. Assuming a real-space pairing scenario, we analyze the resulting superconducting gap symmetry and the stability of the paired state as a function of band filling and applied displacement field. Finally, we highlight the interplay between superconductivity and non-trivial topology, detailing how interaction-induced effects and the evolution of the density of states shape the resulting superconducting phase diagram.
Superconductivity (cond-mat.supr-con)
Non-negative differential mobility of one-dimensional underdamped Langevin dynamics: Proof via mapping to a marginally stable oscillator
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
For an underdamped particle driven by a constant non-conservative force across a periodic potential in one spatial dimension at finite temperature, numerical studies have shown that the differential mobility is non-negative. Here, an analytical proof will be given that is based on expressing the differential mobility by the long-time mean position of a marginally stable harmonic oscillator subject to noise in its stiffness.
Statistical Mechanics (cond-mat.stat-mech)
Failure of Conventional Roughness Metrics in Assessing Field-Limiting Mesoscopic Topography in SRF Nb Films on Cu
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Eric M. Lechner, Brandi Redman, Theodore S. Cahall, Anne-Marie Valente-Feliciano
A characteristic corrugated surface morphology of Nb films on Cu is identified, with mesoscopic features comparable to the London penetration depth and coherence length, and its impact on superconducting radio frequency cavity performance metrics is examined. Magnetic field enhancement factors and superheating field suppression factors are calculated within the London model for a representative corrugated geometry. These results demonstrate that roughness trends derived from buffered chemical polished and electropolished Nb cavities do not capture the impact of nanoscale surface morphology on SRF Nb thin film performance, as even surfaces that possess low average roughness can contain geometric features that generate substantial local field enhancement and significantly suppress the Bean Livingston barrier. The influence of surface roughness on impurity diffusion is also investigated, which highlights the roles of increased surface area and local geometric confinement in modifying near surface impurity distributions. Tracking the effect of impurity diffusion on the evolution of magnetic field enhancement, we show that geometrically confined impurity distributions can mitigate nanoscale magnetic field enhancement substantially.
Superconductivity (cond-mat.supr-con)
Strong-coupling multigap superconductivity in the Heusler compound ScAu$_2$Al
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Jozef Kačmarčík, Zuzana Pribulová, Yevhen Petrenko, Gabriel Kuderowicz, Paweł Wójcik, Michał J. Winiarski, Szymon M. Królak, Filip Košuth, Pavol Szabó, Tomasz Klimczuk, Bartlomiej Wiendlocha, Peter Samuely
ScAu$ _2$ Al is the Heusler superconductor with the highest reported transition temperature, Tc, close to 5 K. Here, we combine high-resolution ac calorimetry and electrical-transport measurements with first-principles-based Eliashberg calculations. The large specific-heat jump, $ {\Delta}C/{\gamma_nT_c} =$ 2.2, well above the weak-coupling BCS value of 1.43, together with an electron-phonon coupling constant $ {\lambda} = $ 1.1, establishes ScAu2Al as a strong-coupling superconductor. The electronic specific heat is described better by a two-gap {\alpha} model, with $ 2{\Delta}_S/k_BT_c = $ 4.1 and $ 2{\Delta}L/k_BT_c = $ 4.8, than by a single-gap model. The thermodynamic upper critical field follows a conventional WHH-like temperature dependence with $ B{c2}(0) = 0.18$ T, whereas the resistively determined critical field reaches values about three times larger and exhibits a pronounced positive curvature. We attribute the enhanced resistive field scale to superconductivity in disordered grain-boundary and interfacial regions. The experimental results are supported by calculations of the heat capacity and upper critical field within the Eliashberg formalism using Fermi-surface and electron-phonon parameters obtained from first-principles calculations
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
7 pages with 7 figures plus Supplemental Material
Tunneling Spectroscopy Study of Low Baked Bulk Niobium for Superconducting RF Cavity Applications
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-21 20:00 EDT
Ivana Curci, Gregoire Jullien, Luc Maurice, Fabien Eozenou, Patrick Sahuquet, Thomas Proslier
Point-contact tunneling (PCT) spectroscopy was used to probe the local superconducting properties of cavity-grade niobium following surface treatments representative of superconducting radio-frequency (SRF) cavities. Electropolished (EP) samples were compared with samples baked at 120$ ^\circ$ C for 48 h and subjected to a two-step bake at 75$ ^\circ$ C for 2 h followed by 120$ ^\circ$ C for 48 h. Although the superconducting gap $ \Delta$ is predominantly distributed around the bulk Nb value (1.5 meV), regions exhibiting strongly suppressed gaps (minigaps) are observed in 15–29% of junctions on EP samples. Their occurrence decreases to 6% after the 120~$ ^\circ$ C bake and to only 1% after the two-step treatment. Spectra exhibiting minigaps are well described by the Usadel proximity-effect model, consistent with superconducting Nb coupled to normal regions that we attribute to hydride formation. These results provide direct microscopic evidence that low-temperature baking suppresses regions of degraded surface superconductivity in cavity-grade Nb. The pronounced reduction achieved by the two-step bake further supports a link between hydride-related proximity effects and the surface superconducting properties governing SRF cavity performance.
Superconductivity (cond-mat.supr-con)
PhonoMC: Occupation-based deviational Monte Carlo for phonon transport with temperature-dependent scattering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Shixian Liu, Fei Yin, Gang Wang, Bin Liu, Ge Zhang, Alexander A. Barinov, Ke Xu
Nanoscale self-heating involves phonon transport across confined geometries, material interfaces, and temperature fields over which the scattering rates can vary substantially. We develop PhonoMC, an occupation-based deviational Monte Carlo method for solving the phonon Boltzmann transport equation within the relaxation-time approximation. A fixed equilibrium state is retained as the deviational reference, while the local temperature reconstructed from the represented energy is used to evaluate mode-dependent scattering rates. Collisions are updated with a separately determined relaxation temperature to conserve energy over each time step, and prescribed lattice heating is introduced by changing carrier occupations rather than continuously adding computational particles. For cross-plane transport through a 100-nm Si film, the deviational formulation reproduces the full-population heat flux while reducing its standard deviation by a factor of approximately 3.3 at (\Delta T=100)K with (10^5) carriers. In contrast, keeping the scattering rates fixed at 300K overestimates the heat flux by 23.7% at (\Delta T=250)~K. Calculations of Si thin films distinguish finite-length effects from surface-scattering suppression, and Si/3C-SiC bilayers are used to examine interfacial thermal resistance. The method is further applied to localized heating in FinFET-like structures, where replacing the lower Si substrate with higher-conductivity 3C-SiC leads to a higher hotspot temperature because of the additional resistance associated with the confined Si region and the Si/SiC interface. These results show that a fixed deviational reference can be combined with local temperature-dependent scattering and sustained heat deposition in a mode-resolved Monte Carlo description of nanoscale thermal transport.
Materials Science (cond-mat.mtrl-sci)
Multi-Resolution Wire-Fencing for Efficient Path Sampling
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Simen Z. Stenersen Michler, Lukas Baldauf, Titus S. van Erp
Path sampling methods enable the computation of thermodynamic and kinetic properties through Monte Carlo (MC) moves that generate trajectories from short forward and backward molecular dynamics (MD) segments. Recently, the wire-fencing move was developed to achieve near-unity acceptance while also rapidly decorrelating successive paths, two properties that are usually in conflict in conventional MC schemes. However, in large systems, such as biomolecular simulations, the frame-saving frequency is often kept low to reduce storage requirements. Likewise, when evaluating the order parameter is expensive, frames are saved less frequently to reduce the associated cost. In either situation, this can severely limit the number of available shooting points, in extreme situations leaving only a single point, typically the one with the highest order parameter value, accessible for shooting. Repeated shootings may then originate from the same configuration, reducing sampling efficiency. Here, we introduce a multi-resolution variant of the wire-fencing move in which selected subtrajectories are propagated at higher temporal resolution than the stored trajectories. This refinement affects only the MC move and does not alter the structure or storage of the generated paths, but enhances the diffusion of shooting points along the trajectory and thereby improves sampling efficiency. The approach is demonstrated on two model systems and a realistic protein–ligand unbinding process, with the latter showing an estimated efficiency improvement of more than an order of magnitude.
Statistical Mechanics (cond-mat.stat-mech)
13 pages, 4 figures
Low resistance NiO/β-Ga_{2}O_{3} heterojunction diodes grown via molecular beam epitaxy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Dagny Sacksteder, Anna Sacchi, Renae Gannon, Michelle Smeaton, Megan E. Holtz, Andriy Zakutayev, M. Brooks Tellekamp
NiO is one of the most important p-type oxide contact materials used in many semiconductor technologies. However, current NiO growth methods can induce interfacial damage that diminishes device performance. Fine control of interfaces is especially important in implementing NiO heterojunction diodes and transistors based on ultra wide band gap (UWBG) semiconductors such as AlGaN and Ga_{2}O_{3} used for power electronic applications. Here, we report on how molecular beam epitaxy can be used to achieve low-defect, lightly doped NiO contact layers for a \beta-Ga_{2}O_{3} diodes. Although high-temperature growth does not measurably decrease the on-state resistance of the diode, increased growth rates up to 600 nm/hr lower on-state resistance in p– NiO / \beta-Ga_{2}O_{3} heterojunction diodes without reducing film quality. At a NiO growth rate of 380 nm/hr, unoptimized diodes with 35 nm thick p– NiO layers demonstrate a device-average specific on-state resistance of 1.46 \Omega-cm^{2} and an ideality factor of 1.46. Individual devices grown at this condition show specific on-state resistance as low as 25 m{\Omega}-cm2 with a rectification ratio of 2.7x106. Scanning transmission electron microscopy imaging reveals the (100) NiO/ (100) \beta-Ga_{2}O_{3} interface is coherent and atomically abrupt. These results open a new avenue to optimizing the NiO interface to produce robust, competitive kV-class power electronic devices based on \beta-Ga_{2}O_{3} and other UWBG semiconductors.
Materials Science (cond-mat.mtrl-sci)
Active colloidal rafts perform swimming strokes that propel their host droplets
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Airi N. Kato, Julien Brémont, Etienne Harté, Jean-Michel Rampnoux, Jean-François Joanny, Hamid Kellay
Active particles confined in droplets can set their host droplet into motion. This phenomenon is usually attributed to direct hydrodynamic forcing by the enclosed particles. Here we reveal a different mechanism: we show that a self-propelled raft of active colloids confined in a thin oil droplet at the surface of water typically follows an off-centered orbit, thus periodically deforming the droplet’s contact line in an anisotropic way. This non-reciprocal deformation acts as a swimming stroke and propels the droplet according to the principles of low-Reynolds-number swimming. The effect is absent for a single colloid and arises from the intrinsically many-body dynamics of the raft, which we capture with a dynamical model coupling viscous hydrodynamics and many-body active dynamics. Our results show how collective internal activity can be converted into locomotion through deformation of a soft confining boundary.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Machine learning magnetic interactions from neutron powder diffraction data
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Adit S. Desai, Yongqiang Cheng, Joseph A. M. Paddison
Neutron diffraction is a versatile experimental technique capable of probing a material’s magnetic properties. While diffraction is typically used to determine the magnetic structure of a material, magnetic diffuse scattering data from a diffraction experiment are also sensitive to the magnetic interactions in its Hamiltonian. However, accurately determining magnetic interaction parameters from neutron-scattering data involves an inverse scattering problem that is challenging to solve in general. Here, we investigate the effectiveness of a machine learning approach to predict the interaction parameters given magnetic diffuse-scattering data measured on powder samples, for a comprehensive survey of isotropic interactions on eight high-symmetry lattices. Across all lattices we considered, the machine-learning approach estimates the interaction parameters with high (~2%) accuracy, while avoiding the issue of false minima that is encountered with non-linear least squares refinement. Our results highlight that powder diffuse-scattering data can provide a compact “fingerprint” of the magnetic interactions for many materials.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
9 pages, 7 figures
Unified Field Bosonization Technique for strongly inhomogenous Luttinger Liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Soundarya P, Venkata Suryanarayana M, Joy Prakash Das
We introduce the Unified Field Bosonization Technique (UFBT), a direct bosonization framework for strongly inhomogeneous one-dimensional Luttinger liquids (LLs) containing static impurities. UFBT incorporates impurity scattering through a symmetrized combination of bosonic phase fields and yields closed-form expressions for arbitrary N-point correlation functions for a broad class of static impurity potentials, including delta barriers, finite barriers and finite wells. The formalism requires neither renormalization-group analysis nor perturbative expansions, providing an analytical description of the inhomogeneous system at the bosonized level. The technique is validated by recovering known limiting cases, showing agreement with the first-order perturbative expansion in the interaction strength, and demonstrating consistency with the Schwinger-Dyson equations. A key result is that the correlation function exponents remain independent of the impurity strength, while the impurity dependence is captured by the spatial structure and amplitudes of the correlation functions. The resulting correlation functions establish a foundation for analytical studies of transport, Friedel oscillations, and the local and dynamical density of states in strongly inhomogeneous Luttinger liquids.
Strongly Correlated Electrons (cond-mat.str-el)
PAOFLOW: an automated suite for ab initio electronic, transport, and topological properties of materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Anooja Jayaraj, Sergio Alvarruiz, Mia Falatko, Zhiren He, Jonathan Red, Caua F. Schuch, Karma Tenzin, Chao Chen Ye, Davide Ceresoli, Marcio Costa, Stefano Curtarolo, Jagoda Slawinska, Marco Buongiorno Nardelli
High-throughput first-principles property calculations are often constrained by costly post-processing and dense Brillouin-zone sampling, impeding the creation of large, internally consistent materials-property datasets and limiting AI-driven discovery workflows. Pseudo-atomic-orbital (PAO) Hamiltonians provide an exact tight-binding representation of first-principles electronic structure that enables the calculation of a wide range of electronic, optical, topological, and transport properties at negligible cost, thereby supporting scalable generation of training-quality data and AI-ready data infrastructures. In this work, we present PAOFLOW 3.0 – an open-source Python suite that automates the construction and analysis of PAO Hamiltonians from plane-wave density functional theory calculations performed with either Quantum ESPRESSO or VASP. The resulting Hamiltonians enable efficient electronic structure interpolation, Fermi surface analysis, optical and dielectric response, transport coefficients, Berry phase and topological quantities, quantum transport, and other materials properties. Compared with previous releases, PAOFLOW 3.0 substantially extends the scope of the package through the introduction of internal projections enabling support for VASP calculations, self-consistent Hubbard U and V corrections obtained using ACBN0 and eACBN0 methods, generation of environment-dependent Slater-Koster tight-binding models, Landauer–BÃŒttiker quantum transport, and calculation of quantum oscillations using the integrated PySKEAF module. The theoretical foundations and the software architecture are presented together with representative calculations illustrating the current capabilities of the package.
Materials Science (cond-mat.mtrl-sci)
Merons Mediate Re-Ordering of Curved Rods Under Shear Flow
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-21 20:00 EDT
Nicholas W. Hackney, Joel T. Clemmer, Thomas O’Connor, Gary S. Grest
Bent-core liquid crystals are a canonical example of a soft matter system whose behavior is controlled by a local preference for order that cannot be universally achieved. This geometric frustration, arising from the rod’s curved shape, has been shown to stabilize a variety of equilibrium phases, such as the helically ordered nematic twist-bend phase ($ N_{\rm TB}$ ). Unlike a traditional nematic, the twist-bend state has 1D translational order arising from a periodic rotation of bend orientation along the helical axis. Here, we use molecular dynamics simulations to study the effect of shearing the $ N_{\rm TB}$ phase along directions parallel and perpendicular to the helical axis. In the case of shear perpendicular to the helical axis, the nematic twist-bend phase is stable and flows without disordering. Conversely, shear along the helical axis disrupts order and leads to the emergence of fractionally charged Skyrmion defects, i.e. merons. These defects act as topological machines, locally rotating rods into a re-ordered and stable orientation of the $ N_{\rm TB}$ phase. These findings reveal a new mechanism to create and control merons and highlight the potential application of bent-core liquid crystals in designing functional material with specific optical and computational properties.
Soft Condensed Matter (cond-mat.soft)
15 pages, 10 figures
Photogalvanic effect in monolayers of transition metal dichalcogenides
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
We present a theoretical study of photocurrents generated by direct optical transitions induced by linearly polarized radiation in monolayers of transition metal dichalcogenides. A microscopic theory of both the ballistic and shift contributions to the photocurrent is developed that accounts for Coulomb attraction between photoexcited electrons and holes. It is demonstrated that, in typical 2D semiconductors, the Coulomb correlation causes the ballistic contribution to dominate over the shift photocurrent.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Insights into the long-standing controversy over sound velocities in lizardite
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Chenxing Luo, Timothy Liao, Hongjin Wang, Renata M. Wentzcovitch
Serpentine minerals are abundant H-bearing phases in the upper mantle and play a central role in water transport in subduction zones. Lizardite is the low-temperature polymorph expected in cold slabs and shallow serpentinized mantle. Using an ab initio thermoelastic framework combining density-functional theory with the r2SCAN meta-GGA and the quasiharmonic approximation, we calculate its compression curve, elastic tensor, and acoustic velocities at 300 K. r2SCAN reproduces the measured compression curve and equilibrium volume to within 0.2%. Weak interlayer hydrogen bonding gives rise to pronounced axial softening, with $ C_{33} \simeq 0.21C_{11}$ and $ C_{44} \simeq 0.13C_{66}$ at 0 GPa. Solving the Christoffel equation over all propagation directions, we construct the velocity density of states (VelDOS), which reveals a high density of slow acoustic modes and other directional features obscured by Voigt-Reuss-Hill (VRH) aggregate averages. Reported experimental velocities preferentially sample the slower portion of this distribution rather than clustering near the VRH values, a correspondence consistent with subtle crystallographic texture or preferential orientation not resolved experimentally. Thus, the appropriate seismic-velocity endmember for lizardite depends on its orientational state, and reliance on VRH velocities alone may lead to overestimation of the degree of serpentinization when seismic observations preferentially sample slow crystallographic directions. Direction-resolved single-crystal measurements and aggregate measurements with independently quantified texture would provide direct tests of this interpretation.
Materials Science (cond-mat.mtrl-sci)
Non-Hermitian impurity scattering in graphene: Boltzmann transport and thermoelectric response
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-21 20:00 EDT
Juan A. Cañas, Daniel A. Bonilla, A. Martín-Ruiz
We investigate charge and thermoelectric transport in monolayer graphene containing a dilute distribution of finite-range non-Hermitian scattering centers. The impurities are modeled as circular complex potentials, whose imaginary component describes local carrier loss or gain. By solving the Dirac scattering problem exactly within a partial-wave approach, we obtain the nonunitary scattering matrix and derive the transport and absorption cross sections, which separately characterize momentum relaxation and net carrier exchange with the environment. To connect the microscopic scattering problem with stationary transport, we formulate a semiclassical Boltzmann description in which an external reservoir compensates the equilibrium particle loss or gain. This leads to an effective relaxation time governed by both elastic momentum scattering and non-Hermitian flux exchange. Using the full energy-dependent relaxation time, we evaluate the Onsager coefficients and the resulting electrical conductivity, electronic thermal conductivity, Seebeck coefficient, Lorenz ratio, and electronic thermoelectric figure of merit. We find that weak gain increases the effective carrier lifetime and enhances both charge and heat conductivities, while absorption produces the opposite behavior. More importantly, gain enhances the magnitude of the thermopower and the electronic figure of merit, whereas loss suppresses them. The Lorenz ratio remains close to the Sommerfeld value, with non-Hermiticity mainly modifying its finite-temperature corrections. Our results show that non-Hermitian scattering provides an additional mechanism for controlling the energy dependence of carrier relaxation and, consequently, the thermoelectric response of graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
13 pages, 5 figures
Symmetry Classification of Multipolar Orders in Crystals: Theory, Property Tensors and Automated Analysis with MagSymMultipoles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-21 20:00 EDT
Maxime Braun, Quintin N. Meier
Many structural and magnetic phases and properties of crystalline materials can be related to the ordering of electric and magnetic multipoles. Examples include ferroelectricity, linear magnetoelectricity, and altermagnetism. Determining the symmetry-allowed multipoles in a crystal is therefore useful for characterizing its ordered phases and physical properties. Here, we present a unified Cartesian framework for decomposing moment tensors of arbitrary rank into ordinary, toroidal, and poloidal multipoles, and for determining, from crystallographic and magnetic symmetry, their ferroic, antiferroic, and noncollinear arrangements within the crystal. We further establish the direct symmetry relationship between multipolar order and the allowed components of associated physical-property tensors in both relativistic and non-relativistic settings.
We implement this methodology in MagSymMultipoles (this https URL), an interactive web application for calculating and visualizing symmetry-adapted electric and magnetic multipoles. The application uses magnetic symmetries both with and without spin-orbit coupling to derive the allowed multipoles as well as the underlying Cartesian moment tensors, making it easy to explore the connection between a given multipolar order and the corresponding physical response tensors. We demonstrate the approach for ferroelectric BaTiO3, antiferroelectric PbZrO3, magnetoelectric Cr2O3, and the altermagnets MnF2, MnTe, and Mn3IrSi. These examples demonstrate how our method allows us to obtain an intuitive picture linking the multipolar order of a material directly to its physical properties, thereby facilitating the interpretation of theoretical and experimental results.
Materials Science (cond-mat.mtrl-sci)
Correlation enhanced magnetism at a superconducting cuprate/manganite interface
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-21 20:00 EDT
Vitor A. M. Lima, Marcello Civelli, Walber Hugo de Brito
Motivated by experimental studies on cuprate-manganite heterostructures, we study a correlated bilayer Hubbard model subject to a local interfacial exchange field using cluster dynamical mean-field theory in the underdoped cuprate regime. We find that superconductivity coexists with a manganite-induced Cu spin polarization. Remarkably, throughout this coexistence regime, the superconducting solution carries a larger magnetic moment than the corresponding constrained normal state. Analysis of the magnetic response shows that this reversal is driven by correlations, which enhance magnetism already in the normal state and even more strongly in the superconducting solution. At stronger exchange fields, superconductivity collapses abruptly, displaying hysteresis consistent with a first-order transition, and a strongly spin-polarized pseudogap emerges. These results show that, under strong electronic correlations, superconductivity can enhance rather than suppress interfacial magnetism.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Universal Eigenvector Statistics of Non-Hermitian Random Matrices
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-21 20:00 EDT
Ze Chen, Zhenyu Xiao, Shinsei Ryu
Eigenvector overlaps quantify nonorthogonality and govern the response and dynamics of non-Hermitian systems. We extend the universality of non-Hermitian random matrices to the statistics of these overlaps. We obtain analytical expressions for eigenvector overlaps in the spectral bulk and near the origin, covering ten symmetry classes in the limit of large matrix size. Using fermionic replica nonlinear $ \sigma$ models, we relate these overlaps to Hermitian level statistics, symmetry class by symmetry class and topological sector by topological sector. Numerical calculations in various physical models support the universality of the normalized overlaps in the regimes studied. Our work establishes a duality between Hermitian level statistics and non-Hermitian eigenvector overlaps.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Research Square
Topological-Insulator Heterophase Gate Stacks for Transistor Electrostatics
Physical Sciences - Article | Electronic devices | 2026-09-20 20:00 EDT
Hoon Hahn Yoon, Minuk Song, Jiwan Kim, MD Gius Uddin, Wonseok Kim, Jihun Park, Han Uk Lee, Dong Won Jeon, Dohyung Lee, Lide Yao, Jouko Lahtinen, Gyunghyun Jang, Soohyun Min, Yonas Megra, Xiaoqi Cui, Seungwoo Choi, Yunyun Dai, Sang Hoon Chae, Keun Su Kim, Dong-Ho Kang, Hyeon-Jin Shin, Wooseok Song, Seth Tongay, Chul-Ho Lee, Manish Chhowalla, Sung Beom Cho, Zhipei Sun, Kibog Park
Conventional gate-stack scaling reduces dielectric thickness and increases permittivity while largely treating the position and electronic character of the gate-side screening boundary as fixed. As equivalent oxide thickness is reduced, however, finite interfacial responses can increasingly constrain gate control [1-5]. Here we show that this screening boundary can itself be engineered by converting the surface of the topological insulator Bi2Se3 into insulating high-κ BiF3. Position-resolved calculations reveal a gap-opened immediate amorphous-BiF3/crystalline-Bi2Se3 interface and a reconstructed gap-closed Bi2Se3-derived state in the adjacent subinterface layer, accompanied by a localized interfacial dipole. Independently, capacitor measurements resolve a finite series response consistent with the electronic compressibility of this buried boundary, which reduces rather than enhances the nominal stack capacitance. Despite this capacitance penalty, MoS2 transistors with closely matched BiF3 thicknesses and a common BiF3/MoS2 channel-side material interface exhibit near-thermionic switching, negligible hysteresis, and approximately sevenfold lower drain-induced barrier lowering than BiF3-only controls. These results identify the position and electronic character of the gate-side screening boundary as additional design variables for transistor electrostatics beyond nominal dielectric capacitance.
Research Square:rs-11089004 (2026)
Posted on Research Square
Physical sciences/Nanoscience and technology/Nanoscale devices/Electronic devices, Physical sciences/Nanoscience and technology/Nanoscale materials/Electronic properties and materials, Physical sciences/Nanoscience and technology/Nanoscale materials/Two-dimensional materials, Physical sciences/Materials science/Condensed-matter physics/Electronic properties and materials, Physical sciences/Materials science/Condensed-matter physics/Surfaces, interfaces and thin films
Lab earthquakes confirm the theory of frictional slip pulses
Article | Surfaces, interfaces and thin films | 2026-09-20 20:00 EDT
Eran Bouchbinder, Alina Shafir, Tom Gabrieli, Yuval Tal
Large natural earthquakes are typically mediated by frictional pulse-like rupture, which features a finite slipping zone [1-6]. Recently, a comprehensive two-dimensional theory of frictional slip pulses has been developed [7-12]. It predicts that pulses are categorically unstable rupture modes, whose evolution is intrinsically slow. Unsteady pulses satisfy an equation of motion expressed in terms of discrete observables, which is inherently related to their steady-state counterparts. The theory also predicts a transition from decaying to slowly growing pulses. Here, we perform extensive lab earthquake experiments to test the theory. The experiments confirm the theoretical predictions for pulse-like lab earthquakes over a range of prestress levels, rupture nucleation conditions and small-scale fault roughness amplitudes. Specifically, the predicted time-dependent dynamics are tested in a plane defined by the evolving pulse size and peak slip rate, along with measurements of the dimensionless growth rate of pulses, demonstrating their intrinsically slow unsteady nature. The predicted transition between decaying and growing pulses is also experimentally demonstrated. These results constitute major progress in understanding a dominant earthquake rupture mode.
Research Square:rs-10771862 (2026)
Posted on Research Square and Under Review at Nature Portfolio
Physical sciences/Physics/Condensed-matter physics/Surfaces, interfaces and thin films, Physical sciences/Materials science/Condensed-matter physics/Surfaces, interfaces and thin films