CMP Journal 2026-07-03
Statistics
Nature Materials: 3
Nature Nanotechnology: 1
Nature Reviews Materials: 1
arXiv: 74
Nature Materials
Programming local confinements in crystalline frameworks through reticular chemistry
Original Paper | Crystal engineering | 2026-07-02 20:00 EDT
Xianhui Tang, Xiaoliang Wang, Zi-Ming Ye, Shengyi Su, Julian S. Magdalenski, Bang Hou, Timothy Y.-Z. Li, Kent O. Kirlikovali, Nathan C. Gianneschi, Haomiao Xie, Omar K. Farha
Controlling local chemical environments within porous crystalline materials is essential for selective adsorption and catalysis, yet remains difficult in stable frameworks with precisely oriented functional sites. Here we use reticular chemistry to programme tunable confinement in triazolate metal-organic frameworks constructed from Kuratowski-type Zn5Cl4 nodes. Linker geometry directs the formation of the ith-d topology, in which terminal Zn-bound groups point inwards to generate confined and chemically addressable pores. This strategy yields two isoreticular frameworks, NU-6000 and NU-6001, with distinct cage dimensions and apertures, while preserving the same topology. Post-synthetic chloride-to-hydroxide exchange installs dense arrays of inward-facing Zn-OH groups without loss of crystallinity, enabling reversible CO2 chemisorption through bicarbonate formation. Single-crystal analysis of a CO2 adduct reveals that confinement imposes a geometric accessibility limit on reactive hydroxyl sites within the smallest cage of NU-6000. Under this confinement regime, NU-6000 exhibits strong low-pressure CO2 capture, including at 30 ppm, and achieves 61.4% site utilization at 420 ppm, among the highest reported for metal-organic frameworks under comparable conditions.
Crystal engineering, Metal-organic frameworks
Single-crystal-like polymer semiconductors via self-templated gradient assembly for ultrahigh charge carrier mobility
Original Paper | Electronic devices | 2026-07-02 20:00 EDT
Wenhao Li, Huajie Chen, Jiawei Deng, Yifei Xu, Kai Chi, Xiaochan Zuo, Zeng Wu, Qingbo Wu, Xin Tao, Xinyuan Zhang, Rui Zeng, Yuqing Ding, Rong Ma, Zhihui Wang, Zhengran Yi, Yanming Sun, Yunqi Liu, Yan Zhao
Achieving high-performance polymer semiconductors is a prerequisite for the fabrication of next-generation organic electronics. However, their multi-scale structural ordering remains challenging due to uncontrollable aggregate assembly, thereby limiting the charge carrier mobility. Here we propose a self-templated gradient assembly strategy to controllably modulate multi-scale ordering and alignment of polymers, substantially improving charge carrier mobility. This strategy establishes selection criteria for solvent systems, relying on the coupling framework of solubility parameters and vapour pressures, to trigger supramolecular ordered assembly. Using a newly designed polymer (PFIDTO-BT), we optimize solution-state aggregates and achieve multi-scale structural ordering, alongside visualized tracking of solution-to-solid hierarchical assembly evolution. The precise control yields highly crystalline ordered thin films and single-crystal-like polymer crystals, showing carrier mobility as high as 11.32 and 37.1 cm2 V-1 s-1, respectively, approaching the performance level of polycrystalline silicon. This work provides a generalized paradigm for the rational fabrication of high-performance organic electronic devices.
Electronic devices, Electronic properties and materials
High-Chern-number orbital magnetism in twisted rhombohedral graphene
Original Paper | Electrical and electronic engineering | 2026-07-02 20:00 EDT
Xirui Wang, L. Antonio Benítez, Skandaprasad Rao, Võ Tiến Phong, Wai In Chu, Kenji Watanabe, Takashi Taniguchi, Cyprian Lewandowski, Pablo Jarillo-Herrero
Realizing Chern insulators with Chern numbers >1 remains a major goal in quantum materials research. Such platforms promise multichannel dissipationless chiral transport and access to correlated phases beyond the conventional C = 1 paradigm. We discover high-Chern-number orbital magnets in twisted monolayer-multilayer rhombohedral graphene, denoted (1 + n) with n = 3, 4 and 5. Magnetotransport measurements show pronounced anomalous Hall effects at one and three electrons per moiré unit cell when they are polarized away from the moiré interface. Across these systems, we observe a clear topological hierarchy C = n, revealed by Středa trajectories and quantized Hall resistance, supported by self-consistent mean-field calculations. Moreover, we realize both electrical and magnetic switching of the high-Chern-number states by flipping the valley polarization. These results establish a tunable hierarchy of orbital Chern magnets in twisted rhombohedral graphene, offering systematic control of Chern number and topology through layer engineering in pristine graphene moiré systems.
Electrical and electronic engineering, Ferromagnetism, Topological matter
Nature Nanotechnology
Monolithic manufacturing of an electrically addressable quasi-suspended nanophotonic aperture
Original Paper | Materials science | 2026-07-02 20:00 EDT
Emma Martin, Md Ishfak Tahmid, Hwi-Min Kim, Lory Marchand, Tanveer Ahmed Siddique, Scott Dhuey, Adam Schwartzberg, Boubacar Kanté
At the nanoscale, electrically injecting carriers into photonic structures remains fundamentally challenging because the conductive pathways required for electrical operation perturb the optical environment needed for strong light-matter interaction. Here we demonstrate a monolithic architecture that overcomes this fundamental trade-off by enabling unit-cell-resolved electrical injection into extended nanophotonic modes while preserving the full semiconductor-air index contrast and the symmetry of the optical cavity. Our approach employs a quasi-suspended photonic crystal aperture supported by an array of subwavelength nanoposts positioned at electromagnetic field nodes of a bound-state-in-continuum mode. This configuration enables uniform carrier injection across hundreds of unit cells without perturbing the optical mode. We show that the transition from single-point to distributed injection introduces a new regime in which the uniformity of electrical properties, not optical properties, becomes the dominant constraint, requiring precise control of nanopost uniformity to achieve lasing. Room-temperature electrically pumped lasing at telecommunication wavelengths demonstrates the viability of this architecture. Our results establish a general framework for decoupling electronic transport from nanophotonic mode engineering.
Materials science, Nanoscience and technology, Optics and photonics
Nature Reviews Materials
Irregular metamaterial networks
Review Paper | Complex networks | 2026-07-02 20:00 EDT
Thomas P. Wytock, Chiara Daraio, Heinrich M. Jaeger, Christopher A. Schuh, Lorenzo Valdevit, Vincenzo Vitelli, Adilson E. Motter
Metamaterials can achieve exceptional functionality through careful design of their mesoscale structure. Although engineered irregularities can be advantageous, current approaches largely conform to regular structures to preserve tractability. Here we contend that network theory, enriched with geometry and physics, provides a natural framework for modelling and designing metamaterials with controlled irregularities at relevant scales. We examine how this augmented network theory can facilitate the creation of irregular metamaterials with enhanced or novel properties and how metamaterial research, in turn, is opening new directions in the broader area of physical networks. Supported by machine learning and advances in self-assembly, the emerging field of irregular metamaterial networks is poised to transform the design and scalable manufacturing of new materials.
Complex networks, Metamaterials
arXiv
On the limits of the energetic coupling between field dislocation mechanics and phase field crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Aymane Graini, Jorge Viñals, Manas V. Upadhyay
This paper investigates the energetic coupling between Field Dislocation Mechanics (FDM) and the Phase Field Crystal (PFC) model proposed in Phys. Rev. B 102, 064109, 2020. While FDM correctly solves the initial boundary value problem of a continuum body with dislocation fields, PFC captures the underlying crystallographic structure. The coupling, which penalizes the $ L^2$ distance between elastic distortion from FDM and configurational distortion from PFC in the $ L^2$ sense, had been proposed to reconcile dislocation mechanics with crystallography in a single continuum framework. Variational analysis reveals that the coupling term acts as a divergence-driven forcing in the phase-field evolution that matches only the compatible (curl-free) parts of the distortion fields. Consequently, its contributions are insensitive to the incompatible (divergence-free) elastic distortion carrying all the information on dislocation topology. Furthermore, the nature of the configurational distortion causes mechanical boundary conditions to be transmitted diffusively from FDM to PFC rather than elastically. Numerical simulations demonstrate that this coupling cannot prevent the unnatural core spreading in FDM. Finally, it is shown that even in the most general case, an energetic coupling suffers from the same drawbacks, which limits its ability to integrate dislocation mechanics with crystallography.
Materials Science (cond-mat.mtrl-sci)
33 pages, 14 figures, preprint
Ising superconductivity and anomalous metallic states in a bulk crystal with artificial unidirectional stacking layers
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-03 20:00 EDT
Xiangqi Liu, Chen Xu, Haonan Wang, Runfeng Zhang, Ziyi Zhu, Zhengyang Li, Lianbing Wen, Ze Yan, Fanbo Shen, Jiawei Luo, Zhengtai Liu, Xia Wang, Leiming Chen, Ke Qu, Jianping Sun, Jinguang Cheng, Shiwei Wu, Zhenzhong Yang, Dawei Shen, Yanfeng Guo
The two-dimensional (2D) limit in macroscopic bulk crystals provides a powerful platform for exploring exotic quantum phases. Here, we report the synthesis of a Sr0.75ClNbS2 superconductor that achieves unidirectional, parallel AA stacking-a configuration never before realized in a bulk crystal. Unlike conventional intercalation, which merely expands the interlayer spacing, our approach employs a planar Sr-Cl network to enforce a complete stacking reorganization, driving all NbS2 layers from the native antiparallel AB stacking into a unidirectional, parallel AA arrangement. This stacking switch globally breaks inversion symmetry, transforming centrosymmetric 2H-NbS2 into a noncentrosymmetric bulk crystal with D3h point group symmetry. Crucially, this structural design reproduces, in three dimensions, the electronic environment of an isolated monolayer, thereby preventing cancellation of the local Ising fields. As a result, strong Ising spin-orbit coupling and spin-split bands persist throughout the bulk. Transport measurements reveal extreme superconducting anisotropy ({\gamma} ~ 77), an in-plane upper critical field (~ 10.65 T) that far exceeds the Pauli paramagnetic limit, and clean-limit superconductivity indicative of high crystalline quality. Moreover, magnetotransport uncovers a novel magnetic-field-induced anomalous metallic state characterized by finite dissipation yet a vanishing Hall response. Direct band-structure measurements corroborate the layer-decoupled, quasi-2D electronic nature of the system. This work establishes stacking-geometry engineering as a powerful strategy to artificially enforce a globally noncentrosymmetric, quasi-2D superconducting state in bulk crystals, paving the way for designing quantum materials with tunable crystalline symmetry and electronic band topology.
Superconductivity (cond-mat.supr-con)
main text 19 pages (4 figures) and SI 15 pages (11 figures)
A Fuzzy Sphere Journey in Critical Phenomena
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
This review discusses the recently proposed fuzzy sphere regularization for studying $ 2+1$ D critical phenomena, particularly three-dimensional (3D) conformal field theory (CFT). The fuzzy sphere scheme not only offers remarkable efficiency in extracting extensive CFT data at low computational cost but also reveals unexpected connections among 3D CFT (critical phenomena), noncommutative geometry, and the quantum Hall effect. We introduce the fundamental ideas of fuzzy sphere regularization, emphasizing its role in demonstrating the state-operator correspondence of 3D CFTs on the $ S^2 \times \mathbb{R}$ geometry. Additionally, we review key developments in this approach across various directions and outline potential future applications.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th)
Invited review. Submitted May 2025; revised September 2025; published March 2026
Annual Review of Condensed Matter Physics 17 (1), 1-25 (2026)
From Dirac Cones to Semions: An Exact Finite-Size Theory of Parity-Anomaly Transport in Chiral Spin Liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Chiral spin liquids carry a hidden bookkeeping problem: the integer Chern number of their fractionalized spinons, the level of the emergent Chern–Simons gauge field, and the fractional spin response actually measured in experiment or simulation are related but distinct quantities, and the literature routinely conflates them. Here we resolve this by deriving the exact parity-odd determinant of a gapped Dirac cone on a spatial cylinder, resummed to all orders in the compact holonomy rather than truncated at leading order. The result proves that finite-circumference corrections to the topological response are strictly exponential, with no universal $ 1/L$ term, and fixes the precise map from microscopic spinon Chern number to physical spin Hall conductance. We validate this chain of reasoning on the kagome lattice at three independent levels: an exact parton band-structure calculation ($ C=-1$ , converging exponentially over cylinders four to twelve sites wide), and an interacting density-matrix renormalization group flux pump ($ \nu_s=-0.500\pm0.011$ ) that agrees with the analytic prediction without any adjustable parameter. Together, these results turn a one-loop anomaly calculation into a quantitatively verified bridge between microscopic topology and observable fractional response.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
22 pages, 2 figures
Quantum Tunneling-induced Hybridization and Coherent Dynamics of Jackiw-Rebbi Zero Modes in a Modified Su-Schrieffer-Heeger Chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
We investigate analytically and numerically the tunneling-induced hybridization and coherent dynamics of Jackiw-Rebbi (JR) zero modes in a modified Su-Schrieffer-Heeger (SSH) model. Unlike the conventional SSH model, this modified system possess two bulk gap closing points, namely, the quadratic-type gap closing point at $ k=0$ and the Dirac-type gap closing point at $ k=\pm\pi/4a$ . While the quadratic point does not support a topological domain wall due to the absence of mass inversion, the low-energy Dirac theory around $ k=\pm\pi/4a$ predicts an effective mass that changes sign at two spatially separated interfaces under a kink profile, generating a pair of JR bound states localized at those interfaces. We show that finite overlap between the JR zero modes lifts the zero-energy degeneracy through quantum tunneling, producing symmetric-antisymmetric hybridized states analogous to a quantum mechanical double-well system. An effective two-level description reveals coherent oscillations of the occupation probability between the two JR modes, accompanied by periodic transfer of sublattice polarization between the (A,C) and (B,D) sectors. The oscillation period is governed by the hybridization gap, providing a tunable route for controlling topological bound states. Our results establish a unified framework connecting JR zero modes, quantum tunneling, and coherent dynamics in modified SSH systems, offering a promising platform for controllable topological quantum-state transfer in engineered lattice structures.
Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 12 figures
Microscopic origins of inertial magnetization dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Caleb Webb, Ling Gan, Shufeng Zhang
Ultrafast experiments have uncovered inertial magnetization dynamics in ferromagnets, but their microscopic origin remains elusive. Using a non-Markovian quantum master equation we show that inertial dynamics arise from coherent interactions with optical phonons in the lattice. The fast optical frequency explains the nutation observed on picosecond timescales and accounts for variations between experiments through substrate-dependent phonon damping. By establishing magnon{phonon coupling as the microscopic basis of inertial magnetization, our results open new pathways for tailoring ultrafast spin dynamics and controlling magnetic states at terahertz frequencies.
Materials Science (cond-mat.mtrl-sci)
Main text: 4 pages 2 figures. Supplementary text: 9 pages 3 figures
First passage time for an underdamped harmonic oscillator and application to the power of an information engine
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Aubin Archambault, Caroline Crauste-Thibierge, Alberto Imparato, Sergio Ciliberto, Ludovic Bellon
The distribution of the first passage time $ t_{fp}$ for the position $ x$ to overcome a threshold $ x_B$ is calculated in an underdamped harmonic oscillator. The proof combines several approaches based on the determination of the eigenvalues of the Kramers differential operator for the intermediate and long time regimes and on a Hamiltonian approximation for the short times. The theoretical predictions are in excellent agreement with the results of an experiment on an underdamped micro-cantilever. The knowledge of the $ t_{fp}$ distribution opens the way to several applications, among them the precise estimation of the power of information engines, which we have also experimentally checked.
Statistical Mechanics (cond-mat.stat-mech)
First passage time distribution in underdamped harmonic oscillators
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Aubin Archambault, Caroline Crauste-Thibierge, Alberto Imparato, Sergio Ciliberto, Ludovic Bellon
We derive the distribution of the first passage time $ t_{fp}$ for the position $ x$ of an underdamped harmonic oscillator to overcome a threshold $ x_B$ . As the $ t_{fp}$ distribution depends on the oscillator quality factor $ Q$ different approaches are used. At very large quality factor ($ Q\gg 100$ ) and intermediate and long $ t_{fp}$ the proof is based on an energy diffusion model, whereas at medium quality factor ($ Q\sim 10$ ) the proof is based on the study of the eigenvalues of the Kramers linear differential operator with absorbing boundary conditions. For all $ Q$ and short $ t_{fp}$ we use a Hamiltonian approximation. The theoretical predictions are in excellent agreement with direct numerical simulations of underdamped oscillator dynamics. Finally we show that the mean of the trajectories ending at $ t_{fp}$ presents a particular shape driven by a specific noise pattern.
Statistical Mechanics (cond-mat.stat-mech)
Vitriflow: calibrated amorphous structure ensembles from melt-quench simulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Jonathon Cottom, Robin Delhomme, Emilia Olsson
Melt–quench molecular dynamics is widely used to construct amorphous materials models, but the resulting ensemble is defined by choices that are often made implicitly: numerical settings, melt temperature, liquid-hold time, quench rate, system size, and post-generation screening. We introduce vitriflow, a computational materials methodology that turns these choices into an explicit decision chain. The framework couples numerical stability, descriptor-based protocol calibration, user-defined artefact screening, and statistical convergence of the generated analysis ensemble in a material-specific descriptor space. We demonstrate the approach for a-SiO$ _2$ , a-Si$ _3$ N$ _4$ , and a-Sm$ _2$ O$ _3$ , which respectively test tetrahedral network fidelity, MG2 $ \rightarrow$ PBE $ \rightarrow$ HSE06 DFT refinement of a heteropolar nitride, and amorphous/crystal discrimination in a mixed-coordination rare-earth oxide. vitriflow separates defect-free from oxygen-bridge-defective silica, quantifies DFT-refinement response in a common a-Si$ _3$ N$ _4$ structural population, and removes recrystallised Sm$ _2$ O$ _3$ structures without imposing fixed coordination. The result is a reproducible route for generating amorphous ensembles whose numerical settings, thermal protocol, screening actions, and statistical precision are selected from the materials question rather than assumed a priori.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Generalized quantum geometry formulated through interacting vertex correlations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Alejandro S. Miñarro, Gervasi Herranz
Quantum geometry characterizes the variation of electron wavefunctions in solids along a parameter space. Conventionally, crystal momentum is chosen as the parameter, since it couples to electromagnetic fields, offering an interpretation of quantum geometry in terms of dipole matrix elements, polarization fluctuations, and optical responses. However, Bloch momentum is not the only possible parameter space in which a wavefunction can evolve. In this work, we show that quantum geometry can be extended beyond the bare Bloch-band geometry to manifolds whose adiabatic parameters represent deformations of the ground state, including collective bosonic fluctuations, external fields, or structural distortions. We show that the generalized quantum geometric tensor is encoded by correlations of interacting vertices, conjugate to the deformation parameters. By way of illustration, we briefly discuss the application of these extended geometric concepts to manifolds generated by Hubbard-Stratonovich bosonic fields, or Jahn-Teller configurational spaces. The formulation presented here is framed by general manifolds, which extend quantum geometry to generic structural, collective, and interactive many-body systems.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 2 figures
Fabrication of high-quality topological insulator nanodevices from bulk-insulating air-sensitive Sb-Bi$_2$Se$_3$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Linh T. Dang, Ayushi Solanki, Yongjian Wang, Oliver Breunig, Yoichi Ando
High-quality topological insulator (TI) materials are essential for the realization and detection of Majorana bound states (MBSs) in TI-superconductor hybrid platforms. Widely used compensated TIs exhibit substantial disorder and charge inhomogeneity, which may be detrimental for Majorana devices. In this regard, Sb-substituted Bi$ _2$ Se$ _3$ (SBS) is promising, because it is non-compensated and yet achieves very low bulk carrier density. We systematically investigate the impact of thermal processing during microfabrication on the transport properties of SBS. We developed a room-temperature fabrication protocol that preserves the low carrier density of exfoliated SBS upon fabrication of Hall bar and nanowire devices as evidenced from the observation of quantum interference oscillations in nanowires, a large gate tunability, and clear signatures of weak antilocalization (WAL).
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
20 pages total; 9 pages main text with 5 figures and 11 pages of supplement with 8 figures
Resonant cooling of nuclear spins by optically-oriented holes in MAPbI$_3$ perovskite crystals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Mladen Kotur, Dmitri R. Yakovlev, Nataliia E. Kopteva, Bekir Turedi, Maksym V. Kovalenko, Manfred Bayer
Resonant cooling of nuclear spins by photogenerated spin-oriented holes is demonstrated for MAPbI$ _3$ perovskite crystals. It is evidenced by Hanle-effect measurements under helicity-modulated excitation with variable frequency. The resonance position in magnetic field shifts toward higher fields with increasing modulation frequency. The invariance of the Hanle curve upon in-plane sample rotation is consistent with the involvement of $ ^{207}$ Pb nuclei with spin $ I = 1/2$ , which do not exhibit quadrupolar splitting. The shape of the resonance feature in the Hanle curve reveals that the nuclear spins are cooled by carriers with a negative $ g$ -factor, consistent with holes. The resonance fields associated with the modulation frequencies exceed the half-width of the weakly localized hole contribution to the Hanle curve, indicating that strongly localized holes are the primary carriers responsible for the nuclear spin cooling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 3 figures
Elasto-Hydrodynamic Propulsion of a Magnetically Actuated Filament
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Sohum Kapadia, Julien Chopin, Arshad Kudrolli
We investigate the low-Reynolds-number propulsion of a slender elastic filament with a dipolar magnetic head actuated by an oscillating field in a viscous fluid by studying its strokes and net forward motion. To capture these dynamics, we employ an elasto-hydrodynamic (EH) framework that couples Euler-Bernoulli beam mechanics with resistive force theory. Unlike prescribed-kinematics models, filament shapes here emerge self-consistently from the actuation and the force and torque boundary conditions (BCs). We demonstrate that viscous boundary contributions are crucial for quantitative agreement and show that the swimming dynamics are governed by the EH length and a magneto-viscous-elastic stroke amplitude introduced here. The swimming speed is non-monotonic with increasing ratio of the swimmer length to the EH length, and is shown to reach a maximum when the swimmer length is on the order of the EH length. We further discuss the analytical limit in which the tail BCs can be described as free, and the limitations that arise when viscous contributions to the BCs are ignored.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
6 pages, 5 figures
Nonperturbative Nonlinear Hall Effect in Nonequilibrium Steady States
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Lei Geng, Martin Eckstein, Lei Chen, Shouvik Sur, Silke Paschen, Qimiao Si, Philipp Werner
The nonlinear Hall effect in quantum materials has attracted broad interest, yet most existing studies focus on the weak-field, perturbative regime. Here we develop a nonperturbative approach based on nonequilibrium steady-state Green’s functions for dc-field-driven lattice systems, with dissipation and interactions incorporated through self-energies beyond the constant relaxation-time approximation and interband transitions treated alongside their intraband counterparts. Applied to a two-band semimetal model, our approach provides direct access to the strong-field Hall response beyond the nonperturbative crossover where the edge of the nonequilibrium distribution reaches Berry-curvature hot spots, a regime in which constant relaxation-time estimates and Berry curvature dipole calculations become unreliable. We further demonstrate that interaction and electron-phonon self-energies within dynamical mean-field theory can substantially change the Hall signal. Our framework enables quantitative simulations of nonequilibrium nonlinear Hall phenomena and provides guidance for strong-field transport experiments.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Mixing induced by microswimmers as probed by mutual information
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Yihong Shi, Yuto Hosaka, Andrej Vilfan, Ramin Golestanian
We investigate fluid mixing induced by microswimmers using mutual information as a global, information-theoretic measure of mixing efficiency. For a two-dimensional squirmer model in a confined domain, we compute numerically the swimmer-generated flows and solve the advection-diffusion equation for the transport of tracer particles in the fluid. We show that the spatial distribution of swimmers strongly affects mixing, which is suppressed by swimmer aggregation and enhanced by positional and orientational disorder. At fixed energy dissipation, mixing efficiency depends non-monotonically on the squirmer parameter, with an optimal finite value arising from the balance between swimmer translation and dipolar flow generation. When hydrodynamic interactions are included, pushers outperform pullers. The mutual information as a function of time decays in three stages: an initial diffusion-dominated stage, an intermediate advection enhanced regime, and a final relaxation stage controlled by system size. Our results demonstrate that mutual information, previously validated as a measure of mixing efficiency only in simplified model systems, can equally be used in complex flows. Its application reveals that mixing by microswimmers is subject to a trade-off between the generation of strong shear flows and achieving optimal dispersion across the fluid domain.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Tuning nonlinear waves in nonreciprocal active filaments
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Sami C. Al-Izzi, Jack Binysh, Yao Du, Corentin Coulais, Andreas Carlson
The instabilities of slender structures power biological locomotion across scales, and offer a compelling method to actuate soft robots. Nonreciprocal elastic solids have been found to amplify flexural waves in one direction only, but design principles to tune and stabilize these waves are missing. Here we develop a geometrically exact theory of nonreciprocal filaments and provide simulations that capture their post-instability nonlinear dynamics. We find that nonreciprocity, when coupled to inertia or pre-stress, amplifies and advects curvature variations. The resulting one-way patterns of shape morphing can then be selected via dissipative interactions with the environment. Our work offers a continuum-based strategy for how internal stresses can drive active unidirectional waves without need for additional degrees of freedom.
Soft Condensed Matter (cond-mat.soft)
15 pages, 7 figures
Phase-selective orbital-charge conversion in $\mathrm{MoTe_2}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
J. L. Costa, E. Santos, G. R. Gallo, G. Rodrigues-Junior, R. O. Cunha, E. L. T. França, R. Cardias, T. G. Rappoport, J. B. S. Mendes, A. Azevedo
Two-dimensional transition metal dichalcogenides (TMDs) have emerged as promising materials for spin–orbitronics owing to their strong spin–orbit coupling and rich electronic phases. However, their orbital transport properties remain largely unexplored. Here, we demonstrate that the orbitronic response of $ \mathrm{MoTe_2}$ is governed by a thickness-driven structural phase transition. RF-sputtered $ \mathrm{MoTe_2}$ thin films exhibit a crossover at a critical thickness of approximately $ 4.5,\mathrm{nm}$ , stabilizing in the metallic $ 1T^\prime$ phase below this threshold and in the semiconducting $ 2H$ phase above it. Raman spectroscopy and scanning tunneling spectroscopy (STS) confirm the structural and electronic transition, revealing gapless behavior in ultrathin films and a finite band gap in thicker samples. Spin-pumping measurements detect an additional transverse charge-conversion signal exclusively in metallic $ 1T^\prime$ -$ \mathrm{MoTe_2}$ , in agreement with first-principles calculations that identify a dominant orbital Rashba–Edelstein response as the underlying conversion mechanism.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15vpages, 4 figures
Intrinsically low thermal conductivity of stoichiometric lithium niobate:Experimental measurement and microscopic origin
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Wenjiang Zhou, Fuwei Yang, Yuxi Wang, Weiheng Li, Wujuan Yan, Kexin Zhang, Bai Song
With the rapid development of integrated electro-optic and nonlinear optical devices based on lithium niobate (LiNbO$ _3$ , LN), thermal management is becoming a critical area of focus. However, experimental measurement of thermal transport in stoichiometric LiNbO$ _3$ (sLN) remains scarce, and the intrinsic microscopic mechanisms remain to be established. Here, we combine the laser pump-probe technique of frequency-domain thermoreflectance (FDTR) with state-of-the-art machine-learned atomistic simulations to comprehensively investigate thermal transport in sLN. The measured and simulated room-temperature thermal conductivity ($ \kappa$ ) values of sLN agree well, which are orders-of-magnitude lower than that of many classic and emerging semiconductors such as silicon. Furthermore, the temperature-dependent $ \kappa$ exhibits a $ T^{-\alpha}$ scaling with $ \alpha$ near unity, suggesting that thermal transport is dominated by intrinsic phonon-phonon scattering. By comparing sLN with cubic boron arsenide (cBAs) which serves as an ultrahigh-$ \kappa$ benchmark, we reveal that harmonic properties are not responsible for the low $ \kappa$ of sLN, which feature phonon heat capacity and group velocities that are either higher than or comparable to those in cBAs. Instead, the low $ \kappa$ originates from substantially stronger anharmonicity and larger scattering phase space. These two factors collectively suppress phonon lifetimes by 1-2 orders of magnitude, leading to a maximum phonon mean free path of approximately 140 nm. As a result, notable size effects emerge in thin-film sLN below 1 $ \mu$ m, with $ \kappa$ dropping to half the bulk value at 10 nm. Altogether, our findings establish a fundamental understanding of thermal transport in sLN and provide atomistic insights for thermal management in advanced lithium niobate technologies.
Materials Science (cond-mat.mtrl-sci)
Many-body benchmarking of DFT local-registry energetics in bilayer InSe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Jeonghwan Ahn, Abdulgani Annaberdiyev, Jovan Nelson, Nathaniel P. Stern, Hyeondeok Shin
Density functional theory (DFT) is widely used to model twisted bilayers, but the accuracy of the local stacking energetics underlying such models remains uncertain. Here, we benchmark the local-registry landscape of bilayer InSe using diffusion quantum Monte Carlo (DMC). DFT predicts that AB, AAr, and ABr stackings, which share the same interfacial Se registry, are nearly degenerate within 1.5 meV/f.u. and exhibit nearly indistinguishable DFT charge-density responses. DMC instead separates these stackings by 8(5) and 41(4) meV/f.u., while the energy difference between the most stable and least stable registries reaches 60(7) meV/f.u.. These large energy separations show that the stacking energetics are not determined by the interfacial atomic motif alone but depend on the full registry and its associated many-body electronic response. More broadly, these results show that DFT-based moiré models can substantially underestimate local stacking-energy corrugation, with direct consequences for predicted structural relaxation, domain formation, and electronic reconstruction in twisted layered materials.
Materials Science (cond-mat.mtrl-sci)
Quantum Heat Under the Microscope: A Perspective on Cryogenic Scanning Thermal Microscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Valentin Fonck, Jean Spiece, Pascal Gehring
Exploring thermal transport at cryogenic temperatures presents both significant challenges and valuable insights. By uncovering the thermal counterpart of well-known quantum phenomena, researchers investigated fascinating phenomena ranging from the violation of the Wiedemann-Franz law to the quantisation of phonons. One key frontier remains : no existing method can image local heat transport at the nanoscale under cryogenic conditions. In this Perspective, we review the current state state of the art of local heat transport characterisation techniques and highlight their limitations. As a motivation for the development of cryogenic Scanning Thermal Microscopy, we provide five case studies illustrating how this approach could deepen our understanding of exotic quantum phases and enable the emergence of transformative technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nano Futures 9 (2008) 032502
Predicting Novel Stable Materials for Experimental Synthesis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Yuqi An, Sihong Zhu, Joseph Montoya, Xingyu Guo, Zhenbin Wang
Machine-learning-accelerated materials discovery has yielded large numbers of computationally stable compounds, yet many remain experimentally unrealized, underscoring a persistent gap between prediction and synthesis. Here, we introduce a hierarchical screening framework that combines PBE-based thermodynamic stability, efficient dynamical-stability screening enabled by universal machine-learning interatomic potentials, and SCAN-based thermodynamic refinement. Applying this protocol to the 894 stable materials previously reported in Sci. Data 9, 302 (2022), we first curate 603 unique structures, of which only 298 remain thermodynamically stable on the complete PBE phase diagrams, demonstrating the critical role of competing phases in stability assessment. Dynamical screening then identifies 166 materials stable under both harmonic-phonon and finite-temperature molecular dynamics criteria, and SCAN phase diagrams further narrow this set to 109. Finally, by combining decomposition enthalpy with chemical-space completeness, we prioritize 25 candidates as high-confidence targets for experimental synthesis. This work provides a practical protocol for translating stability predictions into experimentally actionable synthesis targets, closing a key gap in machine-learning-driven materials discovery.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
28 pages, 7 figures
Ultrasonic Observation of Slowing Down of Multipole Fluctuations in Sr$_2$RuO$_4$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Ryosuke Kurihara, Mitsuhiro Akatsu, Shunsuke Yaoita, Keisuke Mitsumoto, Yuichi Nemoto, Yoshiyuki Yoshida, Hiroshi Yaguchi, Terutaka Goto
We performed ultrasonic measurements on the unconventional superconductor Sr$ 2$ RuO$ 4$ to investigate the dynamical properties of the electronic states near its superconducting transition temperature, $ T\mathrm{c} = 1.4$ K. We observed an increase in the in-plane transverse ultrasonic attenuation coefficient as the temperature approached $ T\mathrm{c}$ . The ultrasonic attenuation exhibited a Landau-Khalatnikov-type ultrasonic frequency dependence with a typical relaxation time of approximately $ 10^{-10}$ s. Under an applied magnetic field of 10 T, the superconducting transition was suppressed. However, the ultrasonic attenuation coefficient exhibited an increase down to low temperatures, indicating the slowing down of fluctuations associated with multipole degrees of freedom. Based on group-theoretical considerations, we propose that the electric hexadecapole plays a crucial role in the slowing down. Furthermore, we discuss the relationship between multi-component superconducting order parameters and multipole degrees of freedom.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
J. Phys. Soc. Jpn. 95, 084701 (2026)
Density functional study of native point defects in CaO
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
We investigate the structural, electronic, and optical properties of native point defects in CaO using first-principles density-functional calculations. Oxygen vacancies are favored under O-poor conditions, whereas calcium vacancies dominate under O-rich conditions. Calculated migration barriers and binding energies indicate that vacancy complexes are thermodynamically stable and can survive high-temperature annealing. Optical transition energies, evaluated using the Franck-Condon framework, suggest that several experimentally observed absorption and emission peaks can be attributed to negatively charged vacancy complexes as well as isolated oxygen vacancies.
Materials Science (cond-mat.mtrl-sci)
Evidence for Deconfined Magnetic Order in the Kitaev-$J_3$ Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
We investigate the Kitaev-$ J_3$ honeycomb model using variational Monte Carlo calculations combined with a vison-quasiparticle analysis of the parent Kitaev spin liquid (KSL). We provide evidence for deconfined magnetic phases in which zigzag or antiferromagnetic order coexists with remnant $ \mathbb{Z}_2$ topological structure inherited from the KSL. The optimized variational wave functions retain multiple linearly independent topological sectors on a torus, whereas those of conventional ordered phases collapse to a single sector. The vison-quasiparticle analysis shows that magnetic order naturally arises from vison-pair condensation while single visons remain gapped, yielding a microscopic mechanism for magnetic ordering without immediate confinement. The resulting phases further host gapless spinons with multiple Majorana cones, offering a possible microscopic scenario for the anomalous low-temperature longitudinal thermal transport reported in magnetically ordered Kitaev materials such as Na$ _2$ Co$ _2$ TeO$ _6$ . Our results reveal a microscopic route to fractionalized magnetism beyond the conventional dichotomy between magnetic order and spin-liquid behavior.
Strongly Correlated Electrons (cond-mat.str-el)
4.5 pages + Supplementary Material, 4 figures
Quantifying angular momentum of coherently driven circular phonons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Roman Mankowsky, Serhane Zerdane, Shih-Wen Huang, Mathias Sander, Xin Liu, Danylo Babich, Martina Basini, Puneet Kaur, Jan-Chi Yang, Michael Fechner, Urs Staub, Henrik Lemke
The use of intense terahertz (THz) pulses to manipulate low-energy excitations offers a powerful approach for ultrafast control of electronic and magnetic properties in materials. Theory suggests that circular ionic motions driven by THz fields carry angular momentum, potentially generating internal magnetic fields. Recent experiments in nonmagnetic SrTiO3 (STO) have hinted at such THz-induced fields, but their origin remains debated. Here, we employ ultrafast x-ray diffraction to resolve the time-dependent ionic trajectories in STO following excitation by circularly polarized THz pulses. Our analysis reveals that oxygen ions, despite their lower mass, contribute around 90% of the phonon angular momentum. The resulting imbalance between the negatively and positively charged ions provides a clear explanation for the mechanism behind induced magnetism in STO. This work further provides the first quantitative measurement of circular ionic motions and their angular momentum and establishes a general methodology for the investigation of angular momentum transfer in solids, paving the way for new strategies to control topological phonon transport and phonon-driven magnetism in quantum materials.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Elastic Modulus in One-Dimensional Quantum Droplets
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-03 20:00 EDT
Rui Zhang, Tianmiao Zhang, Huan-Bo Luo, Zibin Zhao
Quantum droplets (QDs) are self-bound states of ultradilute quantum fluids stabilized by the interplay between the Lee Huang-Yang (LHY) quantum-fluctuation correction and the mean-field interaction, providing a useful platform for exploring macroscopic quantum phenomena. Recent studies on three-dimensional QDs have introduced the concept of bulk modulus and revealed its connection with the breathing-mode frequency, thereby linking the elastic response of QDs to their collective dynamics. Motivated by this progress, we investigate the elastic modulus of one-dimensional QDs. Based on a super Gaussian variational ansatz, we systematically derive the elastic modulus B and analyze its dependence on the interaction strength and particle number. The analytical predictions are further validated by numerical simulations based on imaginary time evolution and the spatial scaling method. We also establish a quantitative relation between the elastic modulus and the eigenfrequency of the breathing mode. In addition, by incorporating corrections to the droplet width beyond the Thomas Fermi approximation, we obtain the dependence of the ratio {\eta} = B/2 on the control parameters g and N. Unlike the three-dimensional case, where the corresponding ratio follows a simple power-law scaling, the one-dimensional system is affected by the soliton-to-droplet crossover, leading to a more intricate dependence of {\eta} on g and N. Our results show that, in the high-particle-number regime, the elastic modulus asymptotically approaches a limiting value determined mainly by the interaction strength, whereas in the low-particle-number regime it depends on both the particle number and the interaction strength.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
12 pages, 5 figures
Interaction-rotation driven localization-delocalization of eigenstate in Fock space: An exact diagonalization study on trapped Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-03 20:00 EDT
We investigate the localization-delocalization transition and entanglement structure in a finite system of interacting bosons in non-rotating and rotating cases. The many-body eigenspectrum is obtained via exact diagonalization within subspaces of fixed total angular momentum, and the structure of the ground state is analyzed using the inverse participation ratio (IPR), the Shannon entropy (information entropy) and the von Neumann entanglement entropy. In the non-rotating case, a transition from localized to delocalized behavior is observed with increasing interaction strength. The transition is characterized by a decrease in IPR and a corresponding increase in entropy measures, indicating spread of eigenstate weight over all the basis states in the Hilbert space. The effect becomes more pronounced with increasing number of bosons due to the increase of the Hilbert space dimension. In the presence of rotation, the system is driven further toward delocalization. For moderate angular momentum, the eigenstates exhibit partial spreading, while at higher angular momenta a saturation behavior emerges, where further increase in rotation has a limited effect on the localization properties. However, the saturation weakens with increasing system size, indicating a nontrivial interplay between rotation and number of bosons. The consistent behavior of IPR, information entropy and von Neumann entanglement entropy demonstrates that these measures provide a unified characterization of the localization-delocalization transition. The results highlight the combined role of interaction strength, rotation and number of bosons in driving the system towards delocalized state. We observe a connection between localization-delocalization and entanglement, with localized states exhibiting weaker entanglement and delocalized states showing stronger entanglement.
Quantum Gases (cond-mat.quant-gas)
10 pages, 4 figures
Fermiology and spin polarization of topological surface states in PtBi$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-03 20:00 EDT
Anders Christian Mathisen, Xin Liang Tan, Stefanie Suzanne Brinkman, Kristian Mæland, Fabian Göhler, Øyvind Finnseth, Grigory Shipunov, Falk Pabst, Manuel Alonso Lemos, Balasubramanian Thiagarajan, Craig Polley, Björn Trauzettel, Anna Isaeva, Jorge I. Facio, Hendrik Bentmann
Layered PtBi$ _2$ is a candidate for topological superconductivity arising in Fermi-arc surface states. Using spin- and angle-resolved photoemission spectroscopy, we demonstrate that the Fermi arcs in PtBi$ _2$ are singly degenerate and spin-polarized, which establishes their nontrivial topology and constitutes a necessary condition for topological superconductivity. We further uncover a pronounced surface-termination dependence of the Fermi-arc dispersion, yielding either nearly flat or approximately linear bands in agreement with first-principles calculations. Together, the observed spin polarization and termination-dependent bandwidth of the Fermi-arc surface states identify key ingredients underlying the potential emergence of topological superconductivity in PtBi$ _2$ .
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Curvature-driven wall accumulation in chiral active particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Alessandro Petrini, Raphaël Maire, Umberto Marini Bettolo Marconi, Lorenzo Caprini
We study a dilute system of non-motile chiral active particles confined in geometries ranging from straight channels to circular enclosures. Activity is introduced through chiral particle-wall interactions, modeled as tangential wall forces that generate the edge currents characteristic of chiral active matter. Remarkably, although the particles lack self-propulsion, these boundary currents induce density inhomogeneities. We show that boundary curvature drives a wall accumulation phenomenon: particles remain uniformly distributed in straight channels but accumulate near the boundaries of circular confinements. Numerical simulations and a hydrodynamic theory for the density and momentum fields consistently capture this curvature-induced wall-accumulation. These results identify boundary curvature as a fundamental control parameter for chiral edge transport and confinement-induced organization, with potential experimental relevance to spinning colloids and granular spinners.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
HVAF Spraying of NiTi Coatings: Microstructure, Phase Transformation and Shape Memory Behavior
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Sneha Samal, Shrikant Joshi, Stefan Björklund, Mohit Chandra, Akhil Bhardwaj, Jaromír Kopeček, Stanislav Habr, Lukáš Václavek Jan Tomáštík, Ondřej Tyc, Petr Šittner
Depositing various coatings on surface of engineering components with the aim to improve their performance concerning wear, corrosion, friction and thermal protection is already a standard practice. Depositing metallic NiTi shape memory alloy coatings may be a viable alternative for hard ceramic coatings. NiTi coatings offer additional benefits originating from unique functional thermomechanical properties. However, fabrication of thick NiTi coatings turned out to be difficult. Standard electroplating and laser cladding methods are not suitable for NiTi the most widely used plasma spray methods tend to produce chemically inhomogeneous coatings that do not transform martensitically, cold sprayed NiTi coatings suffer from poor adhesion to the substrates. In this work we report on first ever successful fabrication of thick NiTi coatings (100-300 um) that display functional thermomechanical properties and simultaneously show very good adherence to the substrate. We used high velocity air fuel thermal spray method to fabricate NiTi coatings deposited on mild steel using four different sets of processing parameters. Chemical composition, porosity, microstructure, phase transformation and functional thermomechanical properties of the NiTi coatings were evaluated. Although the coatings contain inhomogeneous microstructure, voids, oxide particles, high density of dislocation defects and internal stress, they undergo martensitic transformation upon cooling and or mechanical loading. As sprayed NiTi coatings need to be annealed to display functional thermomechanical properties. Despite their limited tensile strength, the coatings displayed thermal actuation in 3 point bending tests and shape memory effects in nanoindentation and scratch tests.
Materials Science (cond-mat.mtrl-sci)
27 pages, 15 figures, 7 tables
Transition-Metal Tailored $Ga_{2}O_{2}$ Monolayer: From Room-Temperature Gas Sensing to Chemical Scavenging
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Afreen Anamul Haque, Aniket Singha
Pristine $ Ga_{2}O_{2}$ monolayers suffer from poor sensitivity and weak molecular capture, limiting their application in toxic gas detection and environmental detoxification. Here, we employ first-principles density functional theory (DFT) calculations to investigate the gas sensing and scavenging properties of $ Ga_{2}O_{2}$ monolayers substitutionally tailored via seven transition-metals (TM): Pd, Zn, Zr, Mo, Ag, Ti, and Pt. All TM-substituted monolayers exhibit negative formation and binding energies, negligible lattice distortion, and structural stability in molecular dynamics simulations. Performance evaluation against eight toxic industrial and three environmental gases reveals functionalities ranging from selective, reusable room-temperature sensing to permanent molecular capture. Ag substitution exhibits exceptional selectivity for $ NO$ with moderate adsorption strength (~-0.83eV), an up to eight-order-of-magnitude conductivity enhancement, besides facilitating reusable $ O_2$ and $ NO_2$ detection. Additionally, Pd-, Zn-, Zr-, and Mo substitutions tune selectivity toward $ NO$ , $ NO_2$ , $ CO_2$ , $ CO$ , and $ O_2$ . Coming to applications towards toxic gas capture, Zr- and Mo-substituted systems selectively scavenge oxidizing gases, whereas Ti and Pt act as universal scavengers. Further analysis reveals that Pd- and Ag-substituted monolayers remain selective for $ NO$ , while Zn substitution favors $ NO_2$ detection even in ambient atmospheric conditions. Thus, these tailored $ Ga_{2}O_{2}$ monolayers offer a practical platform for atmospheric monitoring and detoxification.
Materials Science (cond-mat.mtrl-sci)
24 pages, 13 figures
An efficient formalism for inertial spin waves: Dzyaloshinskii-Moriya antiferromagnets as case studies
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
De-Yun Zhao, Ri-Xing Wang, Meng-Qiu Cai, Mikhail Cherkasskii, Peng-Bin He
Magnetic inertia, emerging in the ultrafast regime, supports inertial spin waves (SWs) as novel magnetic excitations. Despite considerable efforts devoted to inertial SWs, a systematic formalism for fully characterizing their intrinsic properties, especially chirality and polarization, is still lacking, and inertial SWs in spatially nonuniform magnetic configurations remain poorly explored. Here, we develop a framework for calculating inertial SWs and establish a general definition of their chirality and polarization via the ellipticity angle, a unified parameter encoding frequency sign, phase difference, and elliptical axis ratio. Using this method, we systematically investigate precessional and nutational SWs in uniaxial antiferromagnets with staggered and homogeneous Dzyaloshinskii-Moriya interactions (DMIs), covering uniform collinear, canted, and spiral magnetic configurations. The results reveal that small staggered DMI preserves spin-wave degeneracy, whereas small homogeneous DMI lifts it. Further space-time inversion symmetry breaking in canted and spiral structures fully removes spin-wave degeneracy across the entire Brillouin zone. Long-wavelength nutational SWs behave as backward waves, and flat bands emerge in canted and spiral configurations near a critical inertial relaxation time. In canted and spiral configurations, nutational modes are always lefthanded whereas precessional modes are always righthanded; additionally, the dispersion spectra of the canted configuration can be derived from those of the spiral configuration via band folding. Polarization is wavenumber insensitive for uniform configurations but becomes strongly dispersive for nonuniform ones. This work advances the fundamental understanding of magnetic inertial dynamics and provides theoretical insights for the development of ultrafast magnonic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
A depth resolved investigation of hydrogen uptake in carbon based nanostructures by soft-to-hard photoemission spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Orlando Castellano (1 and 2), Alice Apponi (2), Luca Cecchini (3), Daniele Paoloni (1), Simone Ritarossi (1 and 2), Francesco Pandolfi (3), Ilaria Rago (3), Tien-Lin Lee (4), Samuel Jeong (5), Yoshikazu Ito (5 and 6), Carlo Mariani (3 and 7), Gianluca Cavoto (3 and 7), Francesco Offi (1 and 2), Alessandro Ruocco (1 and 2) ((1) Dipartimento di Scienze, Università degli Studi di Roma Tre, Rome, Italy, (2) INFN Sezione di Roma Tre, Rome, Italy, (3) INFN Sezione di Roma, Rome, Italy, (4) Diamond Light Source Ltd, Didcot, United Kingdom, (5) Department of Applied Physics, Institute of Pure and Applied Sciences, University of Tsukuba, Japan, (6) Tsukuba Institute for Advanced Research (TIAR), University of Tsukuba, Japan (7) Sapienza Università di Roma, Rome, Italy)
Hydrogen chemisorption on graphitic carbon modifies the carbon orbital hybridization from sp2 to sp3, altering both structural and electronic properties. Understanding not only the lateral extent but also the depth distribution of hydrogen uptake in three-dimensional carbon architectures is essential for both fundamental studies and storage applications. To this end, we investigate here the evolution of the C 1s core-level lineshape in nanoporous graphene (NPG) and vertically aligned carbon nanotubes (CNTs) upon hydrogenation, exploiting soft-to-hard X-ray photoemission spectroscopy to achieve a depth-resolved analysis. Decomposition of the C 1s spectra reveals the formation of an sp3 rich overlayer in both systems, with an effective thickness ranging from a fraction of a graphitic monolayer (NPG) to approximately one graphitic layer (CNTs), indicating limited hydrogen penetration beneath the outermost accessible surfaces. Overall, hydrogenation in both materials remains predominantly localized on the surface. These results clarify the spatial distribution of hydrogen in curved and porous graphitic networks and provide quantitative constraints on its chemisorption for carbon-based hydrogen storage applications.
Materials Science (cond-mat.mtrl-sci)
Sandpile Models on complex networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Komlan Fiagbe, Jean-François de Kemmeter, Timoteo Carletti
We investigate the sandpile model on complex networks by developing a branching-process framework that explicitly incorporates dissipation during avalanche propagation. Unlike classical branching descriptions, which assume conservative transport and locally tree-like independence, the present approach introduces grain-loss effects directly into the offspring distribution, yielding generalized generating functions for dissipative avalanche dynamics. In the dissipative regime, avalanche-size distributions acquire exponential cutoffs while preserving topology-dependent scaling behavior. Numerical simulations confirm the theoretical predictions on sparse random networks and reveal systematic deviations in highly structured topologies. In particular, by using Holme-Kim clustered scale-free networks, we show that increasing clustering continuously lowers the avalanche exponent and enhances the probability of large cascades, demonstrating that short cycles generate strong correlations that invalidate the classical independent-branch approx imation. Surprisingly, trees also exhibit substantial deviations from power-law because low edge density and the abundance of leaves constrain avalanche propagation. These results show that dissipation, clustering, and sparse connectivity fundamentally reshape avalanche size distribution of the sandpile model on networks and establish quantitative limits for branching-process descriptions of avalanche dynamics.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
Anisotropic nanoscale coherent polariton transport in CrSBr
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Paritosh Malik, Dogyun Ko, Vita Solovyeva, Chirag Chandrakant Palekar, Imad Limame, Sven Rodt, Kseniia Mosina, Zdeněk Sofer, Alexander Steinhoff, Martin Esmann, Stephan Reitzenstein, Bo Han, Christopher Gies, Christian Schneider
In a combined experimental and theoretical study, we demonstrate anisotropic polariton transport on the nanoscale in the van der Waals antiferromagnet CrSBr. While effective cavity-polariton formation emerges via the self-hybridization of ultra-high oscillator strength excitons with a thin slab photonic mode, the absence of external mirrors facilitates spectroscopic investigation of these polaritons via cathodoluminescence (CL) on length scales determined by the electron wavelength. This direct access allows us to perform precise charting of the polariton landscape with nanometric resolution, and to probe polariton interference phenomena. The main finding of the work highlights that the coherent polariton transport follows the $ C_{2v}$ symmetry of CrSBr, allowing exclusive transport along the crystallographic a-axis, while no coherent feature is found along the b-axis direction. Our work sets the foundation to use CL spectroscopy in cavity-polaritonics in more advanced landscapes, such as photonic crystals or optical lattices, and establishes the technique as a powerful tool to probe anisotropic expansion and relaxation phenomena on the nanoscale
Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures
Anisotropic tunneling through magnetic barriers in 8-Pmmn borophene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Rachid El Aitouni, Sanae Zriouel, Clarence Cortes, David Laroze, Ahmed Jellal
We present a theoretical study of electron tunneling through a magnetic barrier in 8-Pmmn borophene, created by depositing two ferromagnetic strips on the borophene sheet. Using a low-energy effective Hamiltonian that captures the anisotropic Dirac spectrum, we solve the Dirac equation in three regions and impose wave-function continuity at the interfaces. From the resulting spinor solutions, we compute current densities and determine transmission and reflection probabilities as functions of incident energy, angle, and barrier parameters. The transmission exhibits strong anisotropy due to the tilted Dirac cones, with pronounced suppression for specific incident directions, suggesting directional filtering of carriers. We further calculate the conductance using the Landauer-Büttiker formalism, revealing that both magnetic strength and barrier width can tune the charge transport properties. The results demonstrate that engineered magnetic barriers in 8-Pmmn borophene enable precise control over electron flow, offering a platform for anisotropic transport control and tunable quantum devices. The interplay between the intrinsic anisotropy of borophene and external magnetic barriers provides rich opportunities to manipulate Dirac fermions in two-dimensional systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
10 pages, 7 figures. Version to appear in Phys. Lett. A 2026
The Wigner function for Integer quantum Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Yao Wang, Qi-Ming Fu, Huawei Fan, Li Yu, Kang Li
Wigner’s quasi-probability distribution function in phase space is a specialized representation of the density matrix, possessing significant physical importance. In this article, we first review the wave function describing electronic motion in an electromagnetic field under the Landau gauge. Next, based on an introduction to the properties of the Wigner function, we calculate the Wigner function for the integer quantum Hall effect using the integral method.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantum-geometric shift of quasiequilibrium: Origin of nonreciprocal current driven by quantum-metric dipole
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Sota Kitamura, Takahiro Anan, Takahiro Morimoto
We study nonlinear DC electric transport of quantum-metric origin by combining adiabatic perturbation theory with the nonequilibrium Green function approach. The adiabatic ansatz provides a basis for directly treating a DC electric field in the velocity gauge, rather than introducing it as the zero-frequency limit of an AC field. The resulting adiabatic-basis Hamiltonian takes the same form as in the length gauge, enabling a systematic comparison across different formulations. Applying this fully quantum formulation, we find a longitudinal nonreciprocal current governed by the quantum-metric dipole. The essential ingredient is a quantum correction to the distribution function that is absent in semiclassical treatments. We trace this correction to the finite spread of an electron wave packet during relaxation under a bias field, thereby identifying shifted quasiequilibrium as the physical origin of quantum-metric nonreciprocal transport.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 2 figures
A 2048-spin bulk acoustic wave Ising machine for number partitioning and Sudoku
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Venkatesh Vadde, Roman Ovcharov, Victor H. González, Roman Khymyn, Artem Litvinenko, Johan Åkerman
Optical coherent Ising machines based on time-multiplexing have demonstrated significant progress in terms of connectivity and spin scalability. However, they are constrained by large physical footprints, high power consumption, poor thermal stability, and high cost. Here, we present a time-multiplexed Ising machine leveraging propagating wave packets in solid-state delay lines at microwave frequencies, enabling thermally stable, robust, low-power, tabletop, and affordable design. We use two serially connected 20.5 MHz, 707 {\mu}s bulk acoustic wave delay lines supporting 2,048 spins. Our design provides all-to-all connectivity with 15-bit coupling resolution and finds approximate MAX-CUT solutions in 341 ms, potentially scalable to sub-ms by using higher frequency delay lines. Additionally, we demonstrate solutions to number partitioning and Sudoku problems. Compared with state-of-the-art Coherent Ising machines, our machine exhibits four orders of magnitude higher thermal stability. Against the simulated bifurcation algorithm, our design achieves comparable results on the MAX-CUT problem, while outperforming it on the more complex number-partitioning and Sudoku problems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Hardware Architecture (cs.AR), Applied Physics (physics.app-ph)
Plaid-Like Spin Splitting and Chirality of Magnon Bands in Antiferromagnetic MnTe$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Dirk Wulferding, Daehyeon An, Jiwon Choi, Dongmin Mun, Youngsu Choi, Sivasakthi Kuppusamy, Sritharan Krishnamoorthi, Raman Sankar, Myung Joon Han, Se Kwon Kim, Kwang-Yong Choi
Altermagnets constitute an emerging class of magnetic materials that combine compensated antiferromagnetic order with spin-split excitations arising from crystalline symmetries. Despite strong theoretical interest, their experimental identification remains challenging. Here, we demonstrate that helicity- and angle-resolved Raman scattering measurements reveal reduced rotational symmetries of magnons and a pronounced imbalance between left- and right-circular polarization channels, indicating momentum-dependent magnon handedness. First-principles DFT+$ U$ calculations combined with linear spin-wave theory uncover a characteristic plaid-like spin-splitting structure in momentum space. The resulting magnon spin textures are dictated by the unconventional sublattice symmetries of MnTe$ _2$ and closely emulate those of altermagnetic electronic bands. Our work provides evidence of chiral spin-wave excitations unique to this non-coplanar antiferromagnet.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Unconventional Mixed-Parity Magnetism in Rare-Earth Tetraborides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Dong-Choon Ryu, Jae-Ho Han, Bongjae Kim, Chang-Jong Kang
Altermagnetism has advanced the study of compensated magnets by revealing non-relativistic spin splitting, traditionally classified into strictly even- or odd-parity spin textures. Here, we unveil a fundamentally different regime: component-resolved mixed-parity spin splitting in a fully three-dimensional compensated magnet. Using first-principles calculations, tight-binding and $ \mathbf{k} \cdot \mathbf{p}$ models, along with spin-group symmetry analysis, we demonstrate that the non-coplanar ground state of $ \mathrm{TbB}_4$ enforces a unique momentum-space spin texture. The in-plane spin components exhibit odd-parity $ p$ - and $ f$ -wave-like textures, whereas the out-of-plane component retains an even-parity $ d$ -wave altermagnetic character. Crucially, the coexistence of the in-plane odd-parity textures is driven not by relativistic spin-orbit coupling, but by a staggered Berry phase arising from the inherent scalar spin chirality. This mixed-parity structure dictates distinct transport fingerprints, including bulk non-relativistic Edelstein and spin Hall responses, as well as a symmetry-allowed Berry curvature dipole. These results establish the rare-earth tetraborides as a robust platform for engineering complex spin-charge conversion phenomena.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Main manuscript: 10 pages, 4 figures, Supplementary Material: 12 pages, 11 figures, 1 table
Electrical transport in ultra-thin films: from Fuchs-Sondheimer to quantum-confinement
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Ultra-thin films are fundamental components of modern nanoelectronics, where reducing thickness to the few-nanometer scale leads to a dramatic increase in electrical resistivity. For decades, this behavior has been interpreted in terms of classical size effects, primarily surface scattering within the Fuchs–Sondheimer theory and grain-boundary scattering in the Mayadas–Shatzkes model. While these approaches successfully describe transport when the film thickness is comparable to the electronic mean free path, growing experimental evidence indicates that they become insufficient under extreme confinement. This review discusses the crossover from classical scattering to a quantum-confinement regime in which the electronic states available for transport are fundamentally restructured by finite size. We review the recently proposed reciprocal-space confinement theory, which predicts an exponential increase of resistivity with decreasing thickness at the nanoscale, and discuss how it can be combined with classical surface-scattering models to provide a unified description of ultra-thin metallic and semiconducting films. Finally, we summarize recent experimental evidence supporting this picture and discuss its implications for future nanoelectronic devices, nanoscale interconnects, and quantum transport under extreme spatial confinement.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
Invited review
Phonon spectral function of Holstein polaron: Investigation of many-body effects with self-energy and vertex correction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
We study the impact of the many-body effects on the phonon spectral function of Holstein polaron in one-dimension in the antiadiabatic regime by incorporating the contributions from the electron self-energy and vertex corrections within a weak-coupling approach that respects the charge-conserving Ward identity. We find that while the polaronic spectral weight is suppressed due to contribution from the electron self-energy, on the other hand, the same is enhanced due to contribution from the vertex corrections. While strength of both the contributions increases with increasing the wave vector ($ \q$ ) of phonons, they nearly cancel each other for the small-$ \q$ modes so that the polaronic spectral weight is weakly affected due to the many-body effects. For the large-$ \q$ modes near the zone boundary, the net many-body correction is dominated by the contribution of the electron self-energy which increases faster in comparison to that of the vertex corrections with increasing the wave vector thereby resulting in a significant suppression of the polaronic spectral weight. We find that while the weak-coupling perturbative approach provides a reliable estimation of the impact of the many-body effects deep inside the antiadibatic regime, the renormalization of quasiparticle spectrum must be taken into account for an accurate estimation when the phonon energy approaches the electronic bandwidth.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 7 figures
Pore-scale distribution and transport of active particles in a two-dimensional lattice
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Suspensions of motile microswimmers such as bacteria and other active colloids frequently encounter porous environments where obstacles and complex shear flows strongly influence their dynamics. Here, we study the distribution and transport of a dilute suspension of active particles in a square lattice of pillars, which serves as a model porous medium. The microswimmers are modeled as slender point particles, and Brownian Dynamics simulations are performed to determine how their number density and polarization fields change with systematic variations in the medium porosity, polydispersity, flow strength, and self-propulsion strength. We find that in the absence of flow, self-propulsion drives particle accumulation and radial polarization at the pillar surfaces. In the presence of a background flow, particles preferentially accumulate in the wake of pillars and exhibit upstream polarization near their surface, consistent with experimental observations. At moderate flow strengths, topological defects nucleate in the polarization field. These defects are of purely kinematic origin and mark the transition from global upstream swimming at low flow strengths to the coexistence of upstream and downstream swimming regions in the lattice at high flow strengths. The structured lattice studied here provides a controlled framework for isolating the physical mechanisms governing active transport in complex geometries, with direct relevance to transport in structured microfluidic settings.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
23 pages
Path-Measure Dynamics of Attention-Driven World Models: A Nonlocal Onsager–Machlup Approach
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Attention enables a world model to condition on its entire history, providing long-term memory that facilitates long-range predictions. While the local Onsager–Machlup theory in our companion paper assumes a temporally local predictive action, we investigate the conditions under which this locality holds. We derive the predictive path measure for latent dynamics that become non-Markovian due to attention-induced memory, demonstrating that this measure is the projection of a hidden linear Markov augmentation. Eliminating the auxiliary field results in a nonlocal Onsager–Machlup action, where memory manifests as a nonlocal quadratic form rather than a force. These kernels are completely monotone and exactly match a hidden Markov embedding with a finite relaxation spectrum; otherwise, the dynamics remain fundamentally nonlocal. By expanding the action in terms of the scale-separation parameter $ \epsilon=\tau_{\text{mem}}/\tau_{\text{dyn}}$ , we show that the leading order recovers the local action of the companion paper, establishing locality as the short-memory limit of a nonlocal theory. We verify the reversible sector of this expansion term by term against an exactly solvable vector linear model.
Statistical Mechanics (cond-mat.stat-mech)
8 pages
Theory of collective learning in populations of adaptive agents
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Gerhard Jung, Johann Asnacios, Misaki Ozawa, Olivier Dauchot, Eric Bertin
We investigate homogeneous populations of smart active agents that exchange information with their neighbors to perform a decentralized learning process aimed at achieving a prescribed macroscopic state. Such agents may, for example, represent simple microrobots. The exchanged information comprises tunable parameters governing the agent dynamics, referred to as the individual policy, together with an internal memory encoding previously visited states. This memory is used to evaluate a reward that quantifies the success of a policy to achieve the prescribed state. We extend the kinetic-theory description of collective learning in spatially homogeneous systems [Phys. Rev. Lett. 134, 248302 (2025)] and derive formal evolution equations for the distribution of policies across the population. A central outcome of our theory is the emergence of an effective reward function that fully determines the evolution of the policy distribution and encapsulates the microscopic details of the agents physical and memory dynamics. We obtain closed equations for the policy mean and variance which admit explicit time-dependent solutions under the assumption of Gaussian-distributed memories and polices.
To illustrate the framework, we present a series of minimal microscopic models, considering both perfect and partial separation of physical, memory and policy exchange time scales, as well as models with one- and two-dimensional policies. The obtained theoretical results compare well with agent-based numerical simulations. The theory captures key aspects of collective learning, including the influence of population diversity and reward fluctuations on learning performance. Finally, we discuss potential applications to swarm robotics and machine learning, and highlight connections with classical models of biological evolution, including the Replicator equation and the Moran model.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Coherent two-dimensional electronic spectroscopy integrated with confocal back focal plane microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Trideep Kawde, Pavel Trofimov, Anton Trenczek, Matteo Russo, Jasper Wilhelm Schwering, Hélène Seiler
We introduce a setup for coherent two-dimensional electronic spectroscopy in the pump-probe reflection geometry that is integrated with a confocal back focal plane imaging microscope. The angle-resolved capability is utilized to control pump and probe wavevectors, while real space imaging enables co-localization of the collection spots for linear and ultrafast experiments. Compression of pulses down to 20 fs is achieved. We demonstrate the capabilities of this approach on an exfoliated WSe$ _2$ monolayer on Si/SiO$ _2$ . The setup is suited to investigate excitons and exciton-polaritons in 2D Materials and their heterostructures.
Materials Science (cond-mat.mtrl-sci), Instrumentation and Detectors (physics.ins-det)
A density matrix renormalization group approach to quantum point contacts
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Nair Aucar Boidi, Mikhail Kiselev
Using the density matrix renormalization group (DMRG) combined with the correction-vector method, we investigate the competition between an harmonic potential and repulsive interactions in a one-dimensional fermionic system. The parabolic confinement induces spatial inhomogeneity, and by tuning its curvature one can continuously interpolate between a potential well–relevant for cold-atom setups–and a quantum barrier, as realized in mesoscopic systems such as quantum point contacts. We analyze how the ground-state particle distribution evolves with the strength and sign of the confining potential and how the confinement reshapes the spectral weight of the local density of states (LDOS) at the center of the chain. In the barrier regime, a localized peak emerges in the electron part of the spectrum ($ \omega >0$ ) as a direct consequence of the potential. In contrast, in the well configuration and for weak interactions, a localized feature persists but shifts to the hole sector ($ \omega <0$ ). However, for stronger interactions, the LDOS no longer displays clear signatures of the external potential, indicating that correlations dominate over single-particle confinement.
Strongly Correlated Electrons (cond-mat.str-el)
Entropy of Non-Abelian Anyons from Slow Quasiparticle Dynamics in Quantum Hall Interferometers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Non-Abelian anyons emerging in fractional quantum Hall states carry a characteristic entropy, $ \Delta S = k_B \log d$ , where (d) is the anyon’s quantum dimension. This (\mathcal{O}(1)) entropy can, in principle, be extracted from charge measurements of an antidot via Maxwell relations. However, equilibrium charge measurements in fractional antidots have proven to be challenging with conventional charge detectors. Here, we propose a scheme based on an antidot embedded in an interferometer, in which the charge can be inferred from the recently observed time-dependent switching of the interference phase. Performing such non-local charge measurements at equilibrium, the characteristic (\mathcal{O}(1)) entropy of non-Abelian anyons (e.g., $ d = \sqrt{2}$ for the $ \nu = 5/2$ state) can be extracted for intermediate temperatures, which exceed the level spacing of the interferometer edge, but are much smaller than the level spacing of the antidot.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Exact amplitude relations for diffusion-limited aggregation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
It has been known for several decades that the third moment of the multifractal spectrum of the harmonic measure for diffusion-limited aggregates is linked to the underlying fractal dimension of the cluster. We demonstrate, using an argument based on the Hastings-Levitov formulation of diffusion-limited aggregation (DLA) in two dimensions, an even stronger link, connecting the universal amplitude of the third moment to the cluster fractal dimension. This argument can be used for both the standard circular DLA as well as DLA in a cylinder (i.e., with periodic boundary conditions).
Statistical Mechanics (cond-mat.stat-mech), Pattern Formation and Solitons (nlin.PS)
7 pages, 3 figures
Differentiable inverse design of short-range order in high-entropy alloys: from target sro to target property
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Tiancheng Ding, Conrard Giresse Tetsassi Feugmo
Short-range order (SRO) governs the mechanical response of multi-principal-element alloys, but designing an alloy for a target property usually means solving two disconnected problems: building a structure matching a desired SRO pattern, then separately checking its property, with no shared optimization. This work replaces the standard random-swap search (reverse Monte Carlo) with a gradient-based approach: atom occupancy is treated as continuous rather than fixed, so the whole process can be tuned using gradient descent, the same method used to train neural networks. This builder matches random-swap accuracy on small systems, but is six times faster and eight times more accurate on large 4000-atom systems, and scales smoothly to alloys with many elements without extra bookkeeping. A physics-based correction term, adapted from prior two-element work and extended here to many elements, keeps designed structures thermodynamically realistic rather than just numerically matching the target SRO pattern. A small neural network then predicts mechanical properties directly from composition and SRO statistics, closing the loop from target property back to structure. Tested on nine face-centered-cubic and body-centered-cubic alloys, the pipeline captured SRO-driven stiffness changes from -20% to +57%, and cell-size checks showed at least 864 atoms are needed to get the direction and size of these changes right, since the commonly used 108-atom cells can mislead. Against real simulations for a cobalt-chromium-nickel alloy, the method matched three of four target stiffness values within 6%. The method is released as an open-source Python package, anisro, offering a practical route to gradient-based, property-driven alloy design.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Alternative routes to universal diversity scaling in component systems: from proteomes to large language models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Andrea Mazzolini, Leonardo Agasso, Filippo Valle, Michele Caselle, Marco Cosentino Lagomarsino, Matteo Osella
Remarkably common statistical laws characterize the diversity scaling and its fluctuations across a wide range of complex “component systems”. These regularities are often interpreted as signatures of an underlying innovation mechanism driving the growth of component diversity, but the basic ingredients necessary for their emergence remain poorly understood. In particular, from language and technological artifacts to genomes and gene expression patterns, the number of distinct components grows sublinearly with system size, while its variance scales approximately as the square of its mean. This behavior is consistent across diverse systems, raising the question of whether general constraints or emergent principles underlying diversity and innovation define the architectures of realizations with different numbers of components. To address this question, we derive analytical conditions for the joint emergence of these two diversity laws within a broad class of growth models, showing that they require a specific asymptotic dependence of the innovation probability on diversity and system size. We then demonstrate that the same macroscopic laws arise in a different class of models with latent heterogeneity, where quadratic fluctuation scaling always emerges asymptotically as a consequence of general statistical principles, essentially the law of total variance, without explicitly assuming an innovation mechanism or any specific rule for system assembly. We compare these predictions with empirical data from language, genomes, LEGO constructions, and texts generated by large language models. Our results show that empirical diversity scaling laws strongly constrain generative models but do not uniquely identify the mechanisms generating diversity, revealing a close correspondence between innovation-driven growth models and latent-variable descriptions.
Statistical Mechanics (cond-mat.stat-mech)
Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO${3}$/SrTiO${3}$ Superlattice
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Yu-Han Gao, Wen-Xiao Shi, Yuan-Sha Chen, Ji-Rong Sun, Qing-Lin Yang, Xu Yang, Zhuo Deng, Peng-Tao Yang, Zheng Chang, Hong-Mei Feng, Wei He, Xiang-Qun Zhang, Zhao-Hua Cheng
For ultrafast magnetization switching devices, critical slowing down in conventional ferromagnets near their Curie temperature constitutes a key challenge that must be overcome. In contrast to this typical behavior, we observe an anomalous acceleration of demagnetization in CaRuO$ _{3}$ /SrTiO$ _{3}$ superlattices, a moderately correlated weak itinerant ferromagnet. The demagnetization rate increases with rising temperature, pump fluence, and applied magnetic field. To explain these anomalous phenomena, we develop a phenomenological model integrating the three-temperature model with self-consistent renormalization theory. Because the intrinsic gradient magnetism of the superlattice suppresses the typical divergence of specific heat, the conventional thermodynamic bottleneck is bypassed. Our model reveals that this decoupling enables the ultrafast dynamics to be predominantly governed by the spin-fluctuation-driven enhancement of the electron-spin scattering vertex. Our work demonstrates how spatial inhomogeneity can decouple macroscopic thermodynamic singularities from microscopic scattering processes, offering a new paradigm for manipulating ultrafast spin dynamics in correlated quantum materials. The pronounced sensitivity of the demagnetization rate to external parameters further suggests the potential for designing highly tunable ultrafast spintronic devices that leverage enhanced fluctuations near the magnetic instability.
Materials Science (cond-mat.mtrl-sci)
19 pages, 4 figures
Efficient Large-Scale STEM-EELS Simulations With Torched-TACAW
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Martin Osmera, João Vaz, Paul M. Zeiger, Ján Rusz
The time auto-correlation of auxiliary wave functions (TACAW) method enables efficient simulations of ultra-low-loss electron energy loss spectra (EELS) arising from vibrational and magnon excitations. In practical applications to realistic materials systems, however, TACAW calculations become challenging due to the large system sizes required for models containing defects, interfaces, impurities, or grain boundaries, as well as the substantial computational cost and data throughput associated with molecular dynamics and multislice calculations. Here we discuss a practical methodology for large-scale TACAW simulations and present torched-TACAW, a freely available implementation of the TACAW part of the described workflow for efficient STEM-EELS simulations. The overall approach combines molecular dynamics based on foundational machine-learned interatomic potentials, partitioning of elongated supercells, and on-the-fly processing of multislice outputs in order to enable near ab initio quality simulations with tractable memory use and data flow. Using rutile TiO2 as a model system, we analyze important numerical aspects of the method, including windowing and supercell partitioning, and demonstrate atomic-resolution STEM-EELS simulations for thick samples.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
17 pages, 7 figures
Interfacial Strain and Structural Defects Govern the Performance of Tantalum Superconducting Waveguide Resonators
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Moritz Singer, Harsh Gupta, Benedikt Schoof, Elena Willinger, Anton Orekhov, Marc Tornow
Tantalum (Ta) is a promising material for reaching long coherence times in superconducting qubits. A detailed understanding of the underlying structure-property relationship remains elusive though. In the present study, we sputter-deposited 200 nm thick Ta films on high-resistivity silicon (100) substrates at temperatures ranging from T = 20°C to 600°C, as well as on different seed layers (Nb, TiN and TaN). Alpha-Ta thin films were readily obtained at temperatures above 500°C and on all seed layers. The films were characterized in terms of surface morphology, residual-resistance ratio, crystal phase composition and superconducting transition temperature, as well as RF-performance using coplanar waveguide resonators. Internal quality factors of up to 1.5 million were measured at 100 mK in the single-photon regime. Despite similar bulk material properties, alpha-Ta films on different seed layers exhibit markedly different RF-performance, which we attribute to dissimilar strain and structural defects at the substrate-metal interfaces. Williamson-Hall analysis of XRD data reveals a clear correlation between decreasing microstrain and increasing quality factor. Cross-sectional HR-TEM further supports this interpretation by directly resolving interfacial disorder. Our results highlight the critical role of interface engineering in optimizing superconducting thin films for low-loss quantum computing circuitry.
Materials Science (cond-mat.mtrl-sci)
From microscopic fluctuations to susceptibility spectra: single-molecule relaxation in glassy media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Siyang Wang, Jaladhar Mahato, Laura J. Kaufman
Single-molecule (SM) rotational dynamics of fluorescent probes in polystyrene near the glass transition temperature ($ T_g$ ) are investigated over long times to reconstruct susceptibility spectra. The loss spectrum, commonly recorded using external field-driven (frequency-domain) spectroscopy, such as dielectric spectroscopy, is reconstructed from purely thermal SM rotational fluctuations. The results reproduce time-temperature superposition typically seen in dielectric spectroscopy for materials near $ T_g$ and show that the ensemble spectrum is comprised of individual molecular responses to distinct environments.
Soft Condensed Matter (cond-mat.soft)
From Bloch to Néel: Anisotropy-dependent Domain-Wall Character in FePd Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Annika Stellhorn, Alicia Backs, Ekaterina Klyushina, Connie Bednarski-Meinke, Steffen Tober, Denis Vasiukov, Oskar Stepancic, Vítor Alexandre de Oliveira Lima, Lukas Aniansson, Paul Steadman, Manuel Valvidares, Jörg Schwenke, Claudiu Bulbucan, Elizabeth Blackburn
We report an experimental investigation of the depth-dependent domain wall formation in L1$ 0$ -FePd thin films with high perpendicular magnetic anisotropy. Using circular dichroism X-ray resonant magnetic scattering (CD-XRMS) as a function of the incident X-ray angle, we explore the depth evolution of chiral spin textures in two samples with different strengths of magnetocrystalline anisotropy. Combined with CD-STXM, CD-ptychography, and macroscopic characterization of the structural order, magnetic properties, and surface morphology, we relate these observations to differences in the long-range order of the L1$ 0$ phase of FePd. One FePd thin film with very high magnetocrystalline anisotropy, characterized by $ Q{PMA}=1.8$ , exhibits an unexpectedly large Néel contribution. Angular-dependent CD-XRMS directly reveals a smooth transition from a hybrid Bloch-Néel chirality within the upper FePd layer towards a purely Néel-type structure at the lower FePd interface. In the second FePd sample, despite a still relatively large $ Q{PMA}=1.45$ , the domain walls were found to be purely Néel type. These results indicate a crucial role of the long-range structural order in determining the formation of the magnetic structure.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Josephson and Spin Currents in Coupled Polariton Condensates
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
A. Kudlis, I. Yu. Chestnov, A. N. Osipov, A. V. Yulin, I. A. Shelykh
We analyze particle and spin currents in networks of coupled spinor exciton-polariton condensates arranged as plaquettes and regular polygonal rings. In closed geometries, spin-conserving and TE-TM-induced spin-flip tunnelling combine to generate circulating particle currents, hidden spin counterflows, and bond-dependent spin-current patterns. For the minimal geometries - an equilateral triangle, and a square plaquette - we derive analytical expressions for edge-resolved currents from stationary configurations obtained by energy minimization. We then show how particle, in-plane spin, and out-of-plane spin currents partition the parameter plane and provide direct signatures of the equilibrium phases. Finally, we apply the same current-resolved diagnostics to larger rings, where winding numbers and a branch-invariant common-phase coherence metric organize the resulting phase structure.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Disorder-induced superconductivity in graphene
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-03 20:00 EDT
Jannes van Poppelen, Tomas Löthman, Annica M. Black-Schaffer
Correlated phases of matter are typically investigated in crystalline systems, where disorder is considered to be detrimental. However, intriguing exceptions exist, such as superconductivity being enhanced in amorphous realizations of Al and Bi. Here, we demonstrate that superconductivity can even emerge entirely from disorder, using monolayer graphene as an example. In the clean limit, the semi-metallic nature of graphene requires prohibitively strong electronic interactions to achieve superconductivity. Despite the inherently random nature of disorder, we show that introducing low concentrations of vacancies or hydrogenation in graphene provides a large density of low-energy states that easily induce superconductivity. For conventional $ s$ -wave pairing, disorder induces a finite superconducting order parameter for arbitrarily weak attractive interactions. Rather than forming isolated superconducting puddles, global phase coherence is established through a finite superfluid weight of purely geometrical origin. Away from the chiral limit of vacancies, hydrogenation similarly yields a finite transition temperature and nonzero superfluid weight for weak interactions. For unconventional nearest-neighbor pairing, typically more disrupted by disorder, superconductivity exhibits quantum-critical-like behavior, yet phase coherence persists at low interaction strengths, with mixed $ d$ -wave symmetries. Our work demonstrates the robust emergence of macroscopic superconducting phase coherence engineered entirely from microscopic disorder.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn)
6+7 pages, 4+4 figures
How wrong is too wrong: A numerical study on the relevance of positional memory in the generalized Langevin equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Abhir Mehrotra, Fabian Koch, Tanja Schilling
If a generalized Langevin equation contains a potential of mean force, it cannot at the same time contain a linear memory kernel and a fluctuating force that obeys a second fluctuation dissipation theorem in the sense of Kubo, and be exact. As modelers often prefer to use generalized Langevin equations that have the first three properties, one needs to ask how close the model dynamics is to the dynamics of the underlying microscopic system. To test this, we analyze a simple model system in which the potential of mean force can be well approximated by a polynomial of low order. The exact generalized Langevin equation of this model contains memory terms in addition to the linear one. We show that these additional terms, at least for the model system regarded in this article, are important for the dynamics and cannot be neglected if one intends to model core aspects of the underlying system correctly.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 3 figures
Localization and Topological Properties of SU(3) Fermions in non-Abelian Gauge Fields: Color-Orbit Coupling and Color-Flip Fields
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-03 20:00 EDT
Bar Alluf, C. A. R. Sá de Melo
The interplay between disorder, gauge fields, and internal degrees of freedom fundamentally affects localization and topological properties of quantum many-body systems. Motivated by recent experimental realizations of synthetic non-Abelian gauge fields for SU(3) colored fermions, we investigate their localization and topological properties in 1D bichromatic optical lattices consisting of strong and weak laser beams. Describing the non-Abelian gauge field via color-orbit coupling and color-flip (Rabi) fields, we obtain a tight-binding description of trapped SU(3) colored fermions corresponding to a generalized three-color Aubry-André model. We show that these fields explicitly break the conventional self-duality of a simple three-color Aubry-André system. This duality breaking generates mobility regions across the energy spectrum, demonstrating that non-Abelian fields can either enhance or hinder color localization. Using exact diagonalization, density-of-states evaluations, and finite-size scaling of the inverse participation ratio, we obtain phase diagrams that identify regions of extended or localized bulk states. Furthermore, the color-orbit and Rabi fields induce edge states with topological properties. We develop an exact mapping from our 1D disorder model into a 2D color Harper model with a fictitious magnetic flux ratio and dimension controlled by the weak laser beam’s phase. Using this mapping, we evaluate topological invariants, such as the charge-charge Chern number, for edge states emerging in energy gaps, revealing the topological insulating nature of several gapped phases. Lastly, we identify that these topological color-insulator phases can energetically neighbor three configurations: two extended, two localized, or one of each. This sharply contrasts with conventional topological insulators, which always neighbor two extended phases.
Quantum Gases (cond-mat.quant-gas)
Velocity and force autocorrelations in Brownian dynamics with a Lorentz force
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
We derive a general relation between the velocity and force autocorrelation tensors (VACT and FACT) for a Brownian particle subject to an external magnetic field. Using time-symmetry arguments, we show that, for the full Langevin dynamics, the VACT depends only on the FACT, independently of the details of the interaction potential. Under the hypothesis of timescale separation between thermalization and interaction-driven motion, this relation simplifies considerably in the overdamped (Brownian) limit. A central feature of the overdamped result is that, unlike in the field-free case, the part of the VACT that controls the self-diffusion of the particle couples to the antisymmetric part of the FACT, with a coupling strength set by the ratio of the cyclotron frequency to the thermalization rate. We validate and illustrate the formalism on an exactly solvable model: a dimer of charged particles bound by a harmonic potential. Depending on the relative sign of the particle charges, the magnetic field is found to produce either a transient suppression of mobility and diffusion that is fully recovered at long times, or a persistent oscillatory force autocorrelation, regions of negative mobility, and a
long-time suppression of self-diffusion.
Statistical Mechanics (cond-mat.stat-mech)
Hydrodynamics, Renormalization Group, and Universality Classes Far from Equilibrium
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Universality is one of the central organising principles of modern physics, explaining why systems with vastly different microscopic constituents can exhibit identical large-scale behaviour. While the classification of equilibrium critical phenomena through hydrodynamics and the renormalization group (RG) is now well established, our understanding of universality far from equilibrium remains far less developed. In recent years, however, rapid progress - driven in large part by developments in active and living matter - has uncovered a growing range of genuinely nonequilibrium universality classes (UCs) with no equilibrium counterparts. In this review, we present a pedagogical and unified introduction to hydrodynamic and RG approaches to nonequilibrium many-body systems. We first show how hydrodynamic theories can be systematically constructed from symmetry and conservation laws alone. We then introduce perturbative dynamic RG methods and demonstrate how hydrodynamic theories are organised into distinct UCs according to their scaling behaviour. Building on these foundations, we review the diverse nonequilibrium UCs uncovered since 2015, while emphasizing the conceptual connections and unifying physical principles underlying their emergence. We conclude by discussing open theoretical and experimental challenges for the field.
Soft Condensed Matter (cond-mat.soft)
41 pages, 4 figures
Fundamental limitations of single-particle Green’s-function zeroes as probes of many-body topology
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
Emile Pangburn, Olivier Gingras
We show that topological invariants constructed from single-particle Green’s functions (GFs) cannot reliably diagnose the topology of interacting many-body states. Using coupled interacting SSH chains as a minimal example, we demonstrate that a spin-spin interaction can trivialize the many-body ground state without affecting the GF topological invariant. This breakdown originates from the GF’s inability to probe electronic excitations in the Fock sectors responsible for the topological degeneracy. Consequently, GF zeroes are not associated with physical topological quasiparticles and cannot generally characterize interacting topological phases.
Strongly Correlated Electrons (cond-mat.str-el)
Contrarian Majority Dynamics: Violation of Detailed Balance and Nonequilibrium Steady States
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
I revisit the Galam Majority Model (GMM) with contrarian agents from a statistical-mechanics perspective, revealing three fundamental features. First, in addition to the GMM simultaneous-update of small discussion groups, I construct a related single-agent stochastic dynamics, providing a Markovian microscopic representation, which is found to yield the same evolution equation. Second, I show that, contrary to what is often stated in the literature, the GMM closed evolution equation for the opinion density is not the result of a mean-field approximation. Indeed, I derive the conventional mean-field dynamics associated with majority-rule interactions and show that it yields a distinct, probabilistic evolution equation contrary the deterministic GMM equation. I therefore identify the GMM as an iterated mean-field dynamics. Third, I investigate the thermodynamic nature of the dynamics obtained from both single-agent and simultaneous updates. Both are shown to violate detailed balance. However, while Kolmogorov’s cycle condition is satisfied for single-agent updates, it is violated for simultaneous updates, making the departure from equilibrium stronger in the latter case. I then compute the probability flux in the stationary state and show that it is non-vanishing, confirming the absence of an effective Hamiltonian and establishing that the stationary state is a genuine nonequilibrium steady this http URL results clarify the statistical-mechanical foundations of the GMM and establish contrarian majority dynamics as an intrinsically non-equilibrium process with distinct regimes of irreversibility. Contrarians are not thermal noise.
Statistical Mechanics (cond-mat.stat-mech)
10 pages
Correlation and entanglement dynamics of free fermions in disguise
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Dávid Szász-Schagrin, Pablo Bayona-Pena, Lorenzo Piroli, Eric Vernier
We study the nonequilibrium dynamics following a quantum quench in spin chains that can be solved via a mapping to free fermions in disguise. These models feature an exponential degeneracy of all energy eigenvalues, raising the question of the validity of the established framework describing the properties of integrable systems out of equilibrium. We present two main results. First, we develop an analytic method to compute the quasi-momentum distribution function characterizing the generalized Gibbs ensemble, and derive an analytic formula to compute the corresponding expectation values for special observables. Second, we conjecture a modification of the standard formula for the entanglement growth based on the quasi-particle picture, taking into account that each fermion in disguise carries an additional amount of entropy due to the exponential degeneracy of the energy eigenvalues. We test our theoretical predictions against numerical tensor-network computations for different initial states and Hamiltonian parameters. For the local observables, we find excellent agreement. For the entanglement dynamics, we find small deviations suggesting that our conjecture is only approximately correct. Our results represent a first step towards the extension of the established framework of integrable systems out of equilibrium to models hosting free fermions in disguise.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
19 pages, 6 figures
Coupled Spin-Orbital $p$-Wave Magnetism via Structural and Magnetic Chirality
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Tom G. Saunderson, Börge Göbel, Ersoy Şaşıoğlu, Samir Lounis
Helical spin textures represent the minimal realization of $ p$ -wave magnetism which is characterized by momentum-odd spin polarization. Independently, structurally chiral crystals exhibit momentum-odd orbital polarization arising from broken inversion symmetry. Here, we demonstrate that spin-orbit coupling couples these two independent microscopic chirality degrees of freedom, allowing the orbital polarization of a chiral crystal to generate an additional contribution to the $ p$ -wave spin splitting. The resulting spin-orbital state is naturally classified by the relative chirality $ \eta=\chi_{\mathrm c}\chi_{\mathrm m}$ , giving rise to two symmetry-distinct $ p$ -wave phases corresponding to homochiral and heterochiral configurations which can be directly probed by the longitudinal conductivity. These phases exhibit distinct transport signatures, establishing relative chirality as an experimentally accessible symmetry degree of freedom in chiral magnetic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Q-GAIN: A Python Package for Machine Learning and Physically Informed Analysis Applications
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-03 20:00 EDT
M. Doris, S. Guo, S. M. Koh, L. Ritter, A. R. Fritsch, S. Mukherjee, I. B. Spielman, J. P. Zwolak
Here we describe the quantum gas analysis and inference (Q-GAIN) Python package, which enables rapid deployment of machine learning (ML) and physics-informed analysis techniques for cold-atom experiments. Out of the box, Q-GAIN implements classification, object detection, and physics-informed metrics for feature detection in images of atomic Bose-Einstein condensates (BECs). Q-GAIN encourages a natural, module-based workflow: starting with data loading and preprocessing, followed by ML-based feature identification, and ending with conventional analysis techniques. We demonstrate this modularity by configuring Q-GAIN for three ML tasks. First, we demonstrate the basic workflow of the Q-GAIN framework by implementing the standard task of classifying handwritten digits from the MNIST dataset. Then, we re-implement our earlier soliton detection (SolDet) package in the Q-GAIN framework, enabling the detection and analysis of solitonic excitations in time-of-flight data. Finally, we develop an object-detection tool that identifies quantized vortices in images of ring-shaped BECs.
Quantum Gases (cond-mat.quant-gas), Machine Learning (cs.LG)
Submission to SciPost, 20 pages with 4 figures
Bottlenecks in Hamiltonian-Adaptive Resolution Simulation Method for Modeling Interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-03 20:00 EDT
Hari Haran Sudhakar (1), Alessandra Serva (1 and 2), Rocio Semino (1) ((1) Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005, Paris, France. (2) Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459, 80039 Amiens Cedex, France)
The Hamiltonian-Adaptive Resolution Simulation (H-AdResS) method allows to combine atomistic and particle-based coarse-grained models in a single simulation box, which makes it very attractive to model systems containing interfaces or reactive regions surrounded by an interacting environment. In our previous work [arXiv:2604.21867], we implemented H-AdResS in LAMMPS 2023 and extended its use to interfaces, focusing on MOF/CO$ _2$ interfaces as an example. We found that, despite its advantages, using this method properly for this kind of systems is not trivial. In this work, an in-depth analysis of the impact of the choice of thermostatting schemes and long-range electrostatics models is presented. Even though its Hamiltonian formulation enables performing H-AdResS simulations within constant temperatures ensembles, not every thermostat is appropriate. We demonstrate that Langevin thermostat is a reliable choice for this method, while Nosé-Hoover results in artifacts. In addition, we show that using short-range models such as the Damped Shifted Force method for electrostatics, a popular choice for H-AdResS simulations, can lead to non-physical results when modeling interfaces. The need of capping strategies to deal with discontinuities in forces and energies arising from abrupt changes in resolution is also discussed. Finally, the impossibility of changing the definition of the H-AdResS Hamiltonian to include a gradual interpolation of the bonded degrees of freedom is discussed. We hope that this contribution helps the reader to appropriately set up H-AdResS simulations and to assess if this method can be used to accurately model their system of interest.
Materials Science (cond-mat.mtrl-sci)
16 pages, 12 figures
Intrinsic orbital Hall effect in a nonuniform electric field
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-03 20:00 EDT
Min Ju Park, Jongjun M. Lee, Hyun-Woo Lee
Geometric analysis of electronic Bloch states offers a universal framework for understanding electronic properties, yet its role in the transport of orbital angular momentum remains unexplored. In this work, we establish an analytic connection between orbital angular momentum transport and the geometric properties of Bloch wave functions in electronic systems. Focusing on the intrinsic orbital Hall effect in the dc limit under a spatially nonuniform electric field, we show that its conductivity can be expressed in terms of universal geometric quantities, such as the orbital Berry curvature and quantum metric. This formulation provides a term-by-term correspondence with the geometric description of intrinsic charge Hall transport established in previous studies. Using a tight-binding model, we further illustrate that the higher-order orbital Hall response can exhibit enhanced sensitivity to the orientation of an anisotropic sample. Our work deepens the understanding of diverse intrinsic transverse transport phenomena and the role of quantum geometry in electronic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
9 pages, 2 figures
Complex dynamics in the Sherrington-Kirkpatrick game
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-07-03 20:00 EDT
We study the outcome of adaptive learning of a large number of players engaging in sets of two-strategy two-player games. We are interested in typical games, and generate the payoff matrices at random at the beginning. The payoff matrices then remain fixed during the learning process. This provides a game theoretic foundation for the Sherrington-Kirkpatrick (SK) game, recently introduced by Garnier-Brun, Benzaquen and Bouchaud. The original model by these authors is a special case, with no bias towards any strategy. We here determine stability of learning for SK games with general random bias, and find that the nature of the stable state is affected by random fields. We also introduce a grand-canonical version of the SK game, in which players can choose to abstain. We determine the stability of learning for this game. Our analysis confirms that complex situations involving many players are frequently unlearnable, even if each player only chooses between two different actions. The rate with which players lose memory of past payoffs and the competitiveness of the game emerge as key parameters determining whether learning converges to a unique fixed point, whether there are many fixed points, or if the dynamics remains persistently volatile.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Computer Science and Game Theory (cs.GT), Physics and Society (physics.soc-ph)
24 pages, 13 figures in the main paper + 2 in appendix
Curvature-induced host-mediated polarization of active particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-03 20:00 EDT
Giulia Janzen, D. A. Matoz-Fernandez
Polar collective motion commonly arises from alignment interactions, particle anisotropy, or an imposed directional bias. Here we identify a distinct route to polar order that does not rely on alignment interactions between the active particles. We show that non-aligning active Brownian particles embedded in a dense passive medium can develop polar coherence when confined to a compact curved surface. Persistent active motion redistributes stress through the host and creates passive-depleted regions. When the stress-spreading length becomes comparable to the sphere radius, these regions merge into elongated scars that channel active motion and, through feedback with the active flux, promote a common direction of motion. Removing the passive host suppresses polar coherence even though the active particles continue to cluster on the same sphere. Our results establish an environment-mediated route to collective polarity in which symmetry breaking emerges from the coupling between active motion, passive stress redistribution, and compact geometry.
Soft Condensed Matter (cond-mat.soft)
Anomalous thermopower from the drag of overdamped collective modes
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-03 20:00 EDT
G. Mirarchi, G. Seibold, M. Grilli, S. Caprara
Inspired by the observation of a Seebeck coefficient ratio that exhibits a seemingly logarithmic divergence at low temperature in high-temperature superconducting cuprates, we show that a mechanisms similar to the standard phonon drag can give rise to anomalies in the thermopower of a metal, if the dragged collective mode is overdamped, with a damping coefficient that increases with lowering the temperature. Our finding adds a piece to the puzzle of the strange-metal behavior observed in many different systems and supports our proposal that overdamped charge density fluctuations can be responsible of such a behavior in high-temperature superconducting cuprates.
Strongly Correlated Electrons (cond-mat.str-el)
On the emergence of quantum many-body chaos for tunably-broken integrability
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-03 20:00 EDT
Sounak Biswas, Sthitadhi Roy, Roderich Moessner
We develop a quantitative theory for the emergence of quantum many-body chaos as integrability is broken via a tunable parameter. In a circuit model of free fermions, ‘doped’ with a tunable density of integrability-breaking gates, we uncover the microscopic mechanisms underpinning the crossover from early-time integrable behaviour to late-time chaos through the lens of the out-of-time-ordered correlators (OTOCs). The integrability-breaking gates act as local, in spacetime, hotspots which locally amplify the OTOCs such that an accumulation of them eventually leads to fully-developed chaos. We identify the explicit characteristic time and length scales governing this crossover, as well as the dependence of the chaotic OTOC characteristics – such as the butterfly velocity and front broadening – on the integrability-breaking parameter.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
8 pages, 4 figures