CMP Journal 2026-09-18
Statistics
Nature Reviews Physics: 1
arXiv: 95
Research Square: 1
Nature Reviews Physics
Self-organizing memristive networks as physical learning systems
Review Paper | Computer science | 2026-09-17 20:00 EDT
Francesco Caravelli, Gianluca Milano, Adam Stieg, Carlo Ricciardi, Simon A. Brown, Zdenka Kuncic
Neural network software implemented on conventional transistor-based digital hardware is consuming increasing amounts of energy. As a result, there is increasing motivation to explore more energy-efficient methods for achieving machine intelligence. One promising direction is to exploit the inherent nonlinear dynamics of physical systems as a basis for learning. This Perspective highlights an approach that uses physical networks comprised of resistive memory components, which we call self-organizing memristive networks (SOMNs) and that consist of dynamically reconfigurable, self-organizing electrical circuitry. Experiments have revealed the non-trivial interactions within SOMNs, offering insights into their collective nonlinear and adaptive dynamics, and how these properties can be harnessed for learning using different hardware implementations. Theoretical approaches, including mean-field theory, graph theory and concepts from disordered systems, reveal deeper insights into the dynamics of SOMNs, especially during transitions between different conductance states in which criticality and other dynamical phase transitions emerge in both experiments and models. Furthermore, parallels between adaptive dynamics in SOMNs and plasticity in biological neuronal networks suggest the potential for realizing energy-efficient, brain-like continual learning. SOMNs thus offer a promising route towards embedded edge intelligence. The aim of this Perspective is to show how nanotechnology, statistical physics, complex systems and self-organizing principles can converge to offer an opportunity to advance a new generation of physical intelligence technologies.
Computer science, Electronic devices
arXiv
Machine-Learning Exploration of Defect Topologies and Thermodynamic Stability in Graphene with Atomic Vacancies
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Marcos V. N. da Costa, José R. da M. Lima Filho, Kádila R. de S. Oliveira, Raphael M. Tromer, Marcelo L. Pereira Junior
Atomic vacancies and vacancy aggregates control the thermodynamic stability and the functional response of graphene, yet the configurational space spanned by many vacancies at variable concentration and separation is too large to be mapped exhaustively by first-principles methods. Here, we map and rationalize this stability landscape by combining semiempirical atomistic thermodynamics, interpretable machine learning, and symbolic regression. Several hundred defective supercells, built from a 72-atom cell by varying the vacancy concentration and the inter-vacancy distance up to the fourth neighbor, were relaxed with the PM7 Hamiltonian in MOPAC, and the heat of formation was adopted as the stability metric. Each structure was encoded with the Dynamic Collision Fingerprint, a translationally and rotationally invariant descriptor that maps the local topology onto transport-like statistics of virtual probe particles. A gradient boosted decision tree model, optimized by Bayesian hyperparameter search, reproduces the heat of formation of an independent test set with a root mean squared error of approximately 23.5kcal/mol and no evidence of overfitting, and a SHAP analysis identifies the defect concentration and the inter-vacancy distance as the two variables that dominate the stability. Symbolic regression then condenses the learned mapping into a compact closed-form expression that reproduces the heat of formation with a coefficient of determination of $ R^{2} = 0.9966$ , a mean absolute error of 15.51kcal/mol, and a root mean squared error of 24.18~kcal/mol. The workflow turns a high-dimensional structure–stability problem into an interpretable analytical law, providing a transferable route to rational defect engineering in two-dimensional materials.
Materials Science (cond-mat.mtrl-sci)
24 pages and 5 figures
Comprehensive First-Principles Investigation of the Structural, Mechanical, Electronic, and Optical Properties of Homoelemental Phase T-GaN Monolayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Djardiel S. Gomes, Isaac M. Félix, Jorge O. A. L. Torres, Fabio L. L. de Mendonça, Sergio Azevedo, Marcelo L. Pereira Junior
The exploration of non-hexagonal two-dimensional topologies has opened new possibilities for tailoring the properties of group III-V monolayers beyond those accessible through conventional honeycomb phases. In this context, we have investigated the structural, mechanical, electronic, and optical properties of T-GaN, a two-dimensional tetragonal gallium nitride monolayer composed of alternating four- and eight-membered rings featuring coexisting homoelemental (Ga-Ga, N-N) and heteropolar (Ga-N) bonds, using density functional theory (DFT) within the generalized gradient approximation (GGA/PBE) and the hybrid HSE06 functional. The dynamical stability of T-GaN was confirmed by phonon dispersion calculations, which revealed the absence of imaginary frequencies throughout the Brillouin zone, and was further supported by \textit{ab initio} molecular dynamics (AIMD) simulations. The mechanical characterization reveals a pronounced in-plane anisotropy, with critical strains of approximately 16.5% and 7.0% along the $ x$ - and $ y$ -directions, respectively. The electronic band structure analysis indicates that T-GaN is a nonmagnetic semiconductor with an indirect band gap of 0.35eV (PBE) and 1.15eV (HSE06), with the valence band maximum dominated by nitrogen 2\textit{p} orbitals and the conduction band minimum governed by gallium 4\textit{s} and 4\textit{p} states. The optical response was evaluated along three crystallographic directions, exhibiting considerable anisotropy in the absorption coefficient, refractive index, and reflectivity. These findings provide new insights into the physical properties of tetragonal group III-V monolayers and suggest that T-GaN may serve as a promising candidate for anisotropic nanoelectronic and optoelectronic applications.
Materials Science (cond-mat.mtrl-sci)
13 pages and 8 figures
Melting of corundum (α-Al2O3) under compression to 8 GPa: A decreasing melting slope
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Melting of corundum ({\alpha}-Al2O3) has been studied under compression up to 8 GPa using in situ electrical resistivity measurements. The melting temperature increases monotonically from T0 = 2317 K at ambient pressure to 3090 K at 7.7 GPa. Fitting the experimental data to the Simon-Glatzel equation yields the empirical parameters a = 5.60 GPa and c = 0.334, providing a closed-form analytical description of the entire melting boundary. Most significantly, the melting slope, dTm/dp, decreases continuously from 138 K/GPa at ambient pressure down to 78 K/GPa at 7.7 GPa, confirming unequivocal negative curvature of the melting curve (d2Tm/dp2 < 0). This phenomenon is consistent with the preferential densification of the liquid phase and the associated reduction in the volume change upon melting as pressure rises. These findings provide a robust empirical standard for the high-pressure melting of corundum, establishing essential constraints for future ab initio simulations, thermodynamic databases, and geophysical models of alumina-rich deep-Earth systems.
Materials Science (cond-mat.mtrl-sci)
Hysteresis in Atomic Josephson Junctions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
Vijay Pal Singh, Ludwig Mathey, Luigi Amico
Hysteresis and retrapping are hallmarks of underdamped Josephson dynamics, yet they have remained elusive in atomic Josephson junctions. Here, we introduce a velocity-sweep protocol to demonstrate these phenomena in the underdamped regime of an atomic Josephson junction. Specifically, using classical-field simulations of a two-dimensional bosonic superfluid, we show hysteresis in the velocity-imbalance characteristics and determine the retrapping current. The dynamics are quantitatively captured by the resistively and capacitively shunted junction (RCSJ) model. We show that hysteresis originates from persistent phase slips below the critical current, with the associated dissipation mediated by vortex-antivortex pair nucleation at the weak link. The retrapping current follows the Stewart-McCumber scaling of underdamped junctions, establishing a common phase-dynamical framework for atomic and superconducting Josephson junctions.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
7+2 pages, 4+3 figures
Bad metallicity in the semi-quantum regime of the Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Evyatar Tulipman, Vadim Oganesyan, Thomas P. Devereaux, Steven A. Kivelson
Bad metals exhibit approximately $ T$ -linear dc resistivity beyond the Ioffe–Regel limit. That this behavior occurs in systems with radically different ground states suggests it is a generic manifestation of strong local correlations. We test this hypothesis in the infinite-$ U$ Hubbard model with small hole densities using exact diagonalization to compute thermodynamic and transport properties of finite clusters. Upon cooling, we find an intermediate temperature range, an electronic analogue of the semi-quantum regime'' of liquid helium, in which quantum effects produce a roughly $ T$ -independent compressibility, yet the resistivity is $ T$ -linear and exceeds the Ioffe--Regel limit. Entry into this regime is accompanied by the formation of quasi-local ferromagnetic spin cages’’ around doped holes, regions that facilitate local quantum motion embedded in a fluctuating spin background, analogous to the transient crystalline cages thought to control incoherent transport in semi-quantum liquid helium. Remarkably, despite the simplicity of the model, the bad metal behavior found here resembles that seen in various material platforms.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas)
main text: 13 pages, 5 figures; SM: 21 pages, 8 figures
Non-Abelian Anyon Condensation: a Path-Integral Monte Carlo Approach
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Rafael Flores-Calderón, Frank Pollmann, Michael Knap
Transitions out of non-Abelian topological order are difficult to describe in microscopic quantum models with numerical methods that remain tractable at large scales. We develop a sign-free path-integral framework for Kitaev quantum doubles $ \mathcal D(G)$ by organizing single-link perturbations in terms of non-invertible electric and magnetic 1-form symmetries that proliferate distinct anyon species. For any finite group $ G$ , an exact $ \textit{matterization}$ isometry introduces vertex degrees of freedom and maps the link-only model onto a $ G$ gauge–Higgs theory. Furthermore, the 1-form symmetries of the fixed point allow us to define generalized Fredenhagen–Marcu order parameters that become finite when the corresponding anyons condense. For $ G = S_3$ , quantum Monte Carlo simulations show that proliferating a non-Abelian electric anyon drives a first-order transition in which all nontrivial electric anyons condense. In the purely magnetic limit, the model reduces to a $ (2+1)$ D pure $ G$ gauge theory; for $ G=S_3$ , it exhibits a first-order confinement transition, diagnosed by the onset of a Wilson-loop area law and the restoration of an emergent magnetic 1-form symmetry. These results provide a unified numerical framework for non-Abelian anyon condensation, confinement, and generalized symmetry breaking.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
Valley-Helical Superconductivity Driven by Repulsion and Quantum Geometry: Applications to Time-Reversal Symmetric Rhombohedral Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Julian May-Mann, Trithep Devakul, Gal Shavit
Motivated by the recent experimental signatures of chiral superconductivity in valley-polarized graphene- and transition-metal-dichalcogenide-based systems, we investigate the possibility of chiral pairing in the absence of valley polarization or time-reversal symmetry breaking. For systems with opposite Berry curvature in the two valleys, we find that overscreened repulsion (i.e., the Kohn-Luttinger mechanism) can indeed induce pairing of opposite chiralities in each valley, producing a valley-helical state. Moreover, the valley-helical state can outcompete more conventional intervalley paired states at intermediate coupling, despite only the latter having a weak-coupling instability. Using a realistic model of time-reversal-symmetric rhombohedral graphene, we find extended ranges of fillings and displacement fields with dominant valley-helical superconductivity. This occurs for all layer numbers considered here, $ 4\leq N\leq 8$ . We show that the valley-helical states can display topologically projected edge modes, unusual magnetic responses, and intertwined Kekulé-like bond-order; features that can be used to distinguish them from more conventional superconductors.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
5.5 pages, 4 figures, 13-page supplement
Momentum-dependent precessional and nutational spin pumping in a honeycomb antiferromagnet
New Submission | Other Condensed Matter (cond-mat.other) | 2026-09-18 20:00 EDT
Suman Mukherjee, Subhadip Ghosh, Ritwik Mondal
The ultrafast magnetic inertial dynamics on subpicosecond timescales generate an additional high-frequency terahertz nutational resonance. Here, we investigate momentum-resolved spin pumping in a two-dimensional honeycomb antiferromagnet by incorporating spin inertia into the Landau-Lifshitz-Gilbert equation. Using a microscopic two-sublattice model with $ J_1$ -$ J_2$ -$ J_3$ exchange interactions, we calculate the precessional and nutational magnon spectra and their corresponding intra- and inter-sublattice spin pumping contributions throughout the Brillouin zone. For parameters representative of MnPS$ _3$ , we find a pronounced complementary momentum dependence of the two spin pumping channels: the precessional current is strongly suppressed around the $ \Gamma$ point ($ 0.01%$ ) and increases towards the Brillouin zone boundary ($ 100%$ at $ K$ and $ 87%$ at $ M$ ), whereas the nutational current is largest near $ \Gamma$ ($ 100%$ ) and decreases towards the boundary ($ 68%$ at $ K$ and $ 69%$ at $ M$ ). This contrasting momentum dependence provides a means of distinguishing spin nutation from conventional precessional motion. We further demonstrate that the nutational spin pumping current is strongly controlled by the inertial relaxation time $ \eta$ , in contrast to the comparatively weak $ \eta$ dependence of the precessional current. In the small-$ \eta$ regime, our analytical results show that the intra-sublattice nutational spin pumping current exhibits a leading-order dependence of $ 1/\eta^3$ . The spin pumping response can also be tuned through the exchange interaction strengths and magnetic moment. Our further results on the magnetic field dependence of spin pumping reveal that the ratio of nutational spin pumping current increases with magnetic field strength, whereas the corresponding precessional counterpart decreases.
Other Condensed Matter (cond-mat.other)
13 Pages, 8 Figures
Universal Suppression of Dissipation across Conformal Interface in Open Quantum Critical Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Ruhanshi Barad, Tian Wu, Qicheng Tang, Xueda Wen
Conformal interfaces provide an important setting for studying universal transmission phenomena in one-dimensional quantum critical systems. While energy and information transmission across such interfaces are characterized by universal quantities in closed systems, the corresponding role of conformal interfaces in dissipative dynamics is less understood. In this work, we study relaxation in locally dissipative quantum critical chains with a conformal interface and show that a universal characterization emerges at the level of individual relaxation modes. We first show that the relaxation coefficient defined in the recent work [1] from the Liouvillian gap can become non-universal for certain boundary conditions because the mode determining the smallest decay rate can change as the interface transmission is varied. To resolve this ambiguity, we introduce a mode-resolved relaxation coefficient $ c_{\rm relax}$ by continuously tracking the same Liouvillian rapidity mode as a function of the interface transmission. Using analytical and numerical calculations for a critical harmonic chain and a critical free-fermion chain, we find that, in the weak-dissipation regime, $ c_{\rm relax}$ follows the same universal dependence on the interface transmission in all cases considered, independent of microscopic details such as the boundary conditions, dissipation strength, and location of the local dissipation. For boundary dissipation, this universal behavior persists even at finite dissipation strength. Our results establish a universal mode-resolved characterization of relaxation across conformal interfaces in open quantum critical systems.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
31 pages, many figures
Unified Transport and Susceptibility Analysis of a Thin BSCCO Film: From Local Pairing to Global Phase Coherence
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Santu Prasad Jana, Bismaya Ranjan Nayak, Sohini Guin, Akshay Naik, Dhavala Suri, Arindam Ghosh
The superconducting transition in thin high-$ T_c$ films can be significantly broadened by disorder, spatial inhomogeneity, and phase fluctuations. Here, we study the transition in a 30-nm-thick sputter-grown Bi$ _2$ Sr$ _2$ CaCu$ _2$ O$ _{8+\delta}$ (BSCCO) film through electrical-transport and ac-susceptibility measurements. The resistive transition is examined using a Gaussian distribution of local $ T_c$ values and the Ambegaokar–Halperin model, describing spatial variations in superconductivity and thermally activated phase dynamics, respectively. To relate the transport and magnetic responses, we extend the Choy–Stoneham susceptibility model by introducing the superconducting fraction extracted from transport and a temperature-dependent connectivity factor representing the gradual development of Josephson coupling among superconducting regions. The results identify separate temperature regimes corresponding to the onset of local superconductivity, expansion of the superconducting fraction, development of magnetic screening, and establishment of global phase coherence. The transition therefore proceeds progressively, from locally superconducting regions to a connected, phase-coherent state. This analysis provides a common framework for relating spatial inhomogeneity, dissipative phase dynamics, and magnetic screening in inhomogeneous superconducting films.
Superconductivity (cond-mat.supr-con)
Main manuscript: 13 pages, 9 figures, and 1 table. Supplementary Material: 4 pages, 2 figures, and 1 table. Submitted to Physical Review B
Encapsulation epitaxy of air-stable monolayer superconducting films for quantum circuits and qubits
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Xudong Zheng, Sameia Zaman, Kenan Zhang, Connor A Occhialini, Haowei Xu, Zhien Wang, Fangyuan Liu, Luiz Gustavo Pimenta Martins, Sejoon Lim, Tianyi Zhang, Tilo H. Yang, Jiangtao Wang, Yunyue Zhu, Zachariah Hennighausen, Sein Park, Steven Vitale, Kevin Tibbetts, Stephen Margiotta, Phillip Kim, Cong Su, Ju Li, Riccardo Comin, William D. Oliver, Joel Î-j. Wang, Jing Kong
Two-dimensional (2D) superconductors are an emerging platform for strongly correlated physics and quantum information science. Their reduced dimensionality, atomically flat interfaces, and high crystallinity are attractive for realizing compact lumped-element devices in superconducting circuits. However, synthesizing large-area, monolayer 2D superconductors remains challenging because of their susceptibility to oxidation. Here, we report an “encapsulation epitaxy” mechanism that enables the growth of large-area, air-stable, monolayer superconducting NbSe2 films and explore their use in superconducting quantum circuits. A 2D encapsulation layer, such as graphene or hexagonal boron nitride (hBN), pre-deposited on a 3D substrate (e.g., SiO2 or Si3N4), serves both as a template for epitaxial growth of monolayer NbSe2 (1L-NbSe2) underneath it and as a protective cover. This approach produces uniform, large-area (>1-inch) 1L-NbSe2 with greatly enhanced ambient stability, enabling device fabrication in air. The resulting 1L-graphene/NbSe2 heterostructures exhibit robust superconductivity (Tc ~ 1 K) and enhanced charge density wave order (TCDW ~ 177 K), indicative of high material quality. We further integrate 1L-NbSe2 into superconducting circuits using oxidation-free transfer and superconducting edge-contact techniques. The 1L-NbSe2 exhibits a measured kinetic inductance LK ~ 0.7 nH/square, making it suitable for quantum circuits requiring high-kinetic-inductance elements. Encapsulation epitaxy thus provides a route to air-stable 2D superconductors and van der Waals heterostructures, with potential for wafer-scale, monolithic fabrication of superconducting quantum circuitry.
Superconductivity (cond-mat.supr-con), Applied Physics (physics.app-ph)
Pre-submission version. Published in Nature
Nature 656, 349-356 (2026)
Electron $g$-value comparison of paramagnetic muonium and hydrogen centers in rutile TiO$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
T. U. Ito, W. Higemoto, A. Koda
Muonium (Mu) is widely used as a model for isolated hydrogen in condensed matter, but whether its electronic state is truly equivalent to that of hydrogen remains to be tested with an orbital-sensitive probe. Here we use double electron-muon resonance to determine the electron $ g$ values of the paramagnetic Mu center in rutile TiO$ _2$ for magnetic fields along [100], [110], and [001] directions. The obtained $ g$ values closely follow those of the H-related Ti$ ^{3+}$ paramagnetic center in both magnitude and anisotropy. This agreement tests the Mu–H correspondence at the level of the Ti $ 3d$ electronic state and supports a common localized Ti$ ^{3+}$ electronic core for the two centers.
Materials Science (cond-mat.mtrl-sci)
6 pages, 3 figures
Phys. Rev. B 114, L140104 (2026)
Pressure-dependent melting and crystallization of B2-NiAl from neural-network molecular dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
A. S. Onegin, P. R. Levashov, N. M. Chtchelkatchev
We investigate pressure-dependent melting of ordered B2-NiAl using neural-network molecular dynamics with a Deep Potential interatomic model. Melting temperatures are determined from two-phase solid-liquid coexistence simulations over a broad pressure range, yielding the melting curve $ T_m(P)$ . Relative to available experimental and previous molecular-dynamics results, the present calculations predict a stronger increase of the melting temperature with pressure at elevated compression. To assess the thermodynamic consistency of the calculated melting line, we evaluate the enthalpy and volume changes upon melting and compare the Clapeyron slope with the derivative of the fitted $ T_m(P)$ curve. The two estimates are in good agreement over most of the investigated pressure range, supporting the internal consistency of the coexistence results. To probe the character of melting, we perform a layer-resolved composition analysis of the coexistence configurations and find that the coexisting liquid remains essentially equiatomic at all studied pressures, with deviations of the aluminum fraction from the stoichiometric value not exceeding $ 5\times10^{-3}$ . This provides direct atomistic evidence that melting of B2-NiAl remains congruent within the present model. Together, these results establish a thermodynamically consistent pressure-dependent melting description of B2-NiAl and clarify the character of its melting under compression.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Displacement field stabilizes even-denominator and partonic fractional quantum Hall states in the $\mathcal{N}{=}2$ Landau levels of Bernal-stacked bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Rakesh K. Dora, Udit Khanna, Ajit C. Balram
Bernal-stacked bilayer graphene (BLG), in which a graphene layer is stacked atop another and laterally shifted by a lattice constant, offers remarkable tunability in its single-particle states under applied magnetic and displacement fields. Owing to this tunability, recent transport and scanning tunneling microscopy experiments in the presence of a perpendicular magnetic field and finite interlayer displacement fields have observed even-denominator fractional quantum Hall (FQH) states at half-filling in the first excited, namely, $ \mathcal{N}{=}2$ , Landau level (LL) of BLG. In contrast, at zero displacement field, a gapless composite fermion Fermi liquid (CFFL) is realized at half-filling of the $ \mathcal{N}{=}2$ LL. Motivated by these experiments, we compute the phase diagram as a function of the displacement field in the half-filled $ \mathcal{N}{=}2$ LL of BLG by studying the competition between the CFFL and the Moore-Read state—a candidate even-denominator FQH state—by calculating their thermodynamic energies in this setting. We find that the modified effective Coulomb interaction, induced by changes in the single-particle states with increasing displacement field, softens the inter-electronic repulsion at short distances, thereby stabilizing the Moore-Read state over the CFFL in the $ \mathcal{N}{=}2$ LL of BLG. We also study the nature of FQH states at fillings $ 2/5$ , $ 3/7$ , $ 4/9$ , and $ 6/13$ in the $ \mathcal{N}{=}2$ LL of BLG. Our results suggest that, with increasing displacement field, the Jain composite-fermion states at $ 3/7$ , $ 4/9$ , and $ 6/13$ transition into states with distinct topological order that are well-captured by parton wave functions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 + 10 pages
Multiple Andreev Reflection Spectroscopy of Spin-Resolved Proximity States
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
A.A. Golubov, M.Yu. Kupriyanov
We predict a coherent multiple Andreev reflection regime in superconducting nanoconstrictions with parallel proximity-induced exchange fields in the electrodes. The subharmonic gap structure is controlled by reconstruction of the spin-resolved electrode spectra, rather than by a rigid displacement of BCS gap edges. This produces split and redistributed anomalies governed by the interval between the outer gap edge and a shifted exchange induced density of states singularity. The effect survives channel transparency averaging and provides a direct transport probe of spin-resolved proximity states.
Superconductivity (cond-mat.supr-con)
The main paper (11 pages, 4 figures) and Supplement (13 pages, 3 figures)
Multiferroic Quantum Dot in an Artificial van der Waals Heterostructure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Antti Karjasilta, Mohammad Amini, Liwei Jing, Robert Drost, Jose Lado, Shawulienu Kezilebieke, Peter Liljeroth, Adolfo O. Fumega
Quantum dots (QDs) provide a versatile platform for engineering quantum-confined electronic states with functionalities relevant for optoelectronics, spintronics, and quantum technologies. While substantial progress has been achieved in coupling confined states to spin, valley, topological, or ferroelectric degrees of freedom, the realization of a multiferroic QD in which quantum confinement simultaneously intertwines with magnetism and ferroelectricity remains elusive. Here, we engineer a multiferroic QD in an artificial van der Waals heterostructure grown by molecular beam epitaxy under ultra-high-vacuum conditions. The heterostructure consists of ferroelectric SnTe nanoislands deposited on the layered magnet CrBr$ _2$ supported on highly oriented pyrolytic graphite. Combining scanning tunneling microscopy and spectroscopy with ab initio calculations and low-energy tight-binding models, we demonstrate the emergence of spin-polarized discretized electronic states confined within the SnTe islands. Remarkably, the spectroscopic response of the QD strongly depends on the ferroelectric domain configuration of the SnTe nanoislands, demonstrating an interplay between quantum confinement, magnetic exchange, and ferroelectric order at the atomic scale. Our results establish engineered van der Waals heterostructures as a platform for multiferroic quantum confinement and open new routes toward electrically tunable quantum spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 5 figures
Energy partitioning of wave packets in one-dimensional systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Flavia B. Ramos, Imke Schneider, Sebastian Eggert, Rodrigo G. Pereira
We investigate the non-equilibrium dynamics of wave packets in a one-dimensional critical fermionic system and analyze the resulting partitioning of energy between emergent excitations. Starting from a Gaussian wave packet injected on top of the many-body ground state, we follow its real-time evolution using the time-dependent density-matrix renormalization group. We observe that interactions lead to fractionalization of the initial excitation into counter-propagating left- and right-moving modes, whose energies can be resolved in real space. To interpret these results, we employ Luttinger liquid theory, which allows us to derive analytical predictions for the energy carried by the emergent modes. We find good agreement between field-theoretical predictions and numerical simulations in the low-energy regime. In contrast to charge fractionalization, which is completely determined by the Luttinger liquid parameter, we show that energy partitioning is non-universal and depends on details of the injected wave packet, such as its width. Our results provide a real-space characterization of energy partitioning in one-dimensional systems and establish a quantitative comparison between non-equilibrium numerical simulations and the effective field-theory description.
Strongly Correlated Electrons (cond-mat.str-el)
17 pages, 7 figures
The Origin of the Observed Raman Peaks in α-MnTe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Nurul Azam, Syed Mohammad Shahed, Liam T. Schmidt, Sara Bey, Oksana Yastrubchak, Maria F. Munoz, Riccardo Torsi, Thi Hai Yen Pham, Dushyanthini Balasundaram, Resham Babu Regami, Wentao Liang, Imrankhan Mulani, Matthew Matzelle, Vineet Kumar Sharma, Sougata Mardanya, Sugata Chowdhury, Nirmal Ghimire, Patrick M. Vora, Angela R. Hight Walker, Xinyu Liu, Badih A. Assaf, Arun Bansil, Alberto De la Torre, Swastik Kar
The Raman spectrum of the room-temperature altermagnet $ \alpha$ -MnTe is reported to contain unassigned peaks at 120(3) cm$ ^{-1}$ and 140(3) cm$ ^{-1}$ , absent from the predicted phonon spectrum of the material. This has generated considerable debate within the altermagnet community and necessitates urgent resolution. This work establishes that these peaks, together with the 90(5) cm$ ^{-1}$ peak that matches a theoretically predicted mode, are all extrinsic, originating from elemental tellurium formed during air exposure of the surface. Raman spectra of MBE-grown thin films show that these peaks closely match those of elemental tellurium, emerge soon after air exposure, and are absent in AlO$ _x$ -capped films. X-ray photoelectron spectroscopy shows that air exposure breaks Mn–Te bonds and oxidizes Mn within a minute. Cross-sectional scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy reveals that the oxidation leads to Mn out-diffusion, forming a few-nanometer-thick oxide layer above a buried, Te-enriched region, likely responsible for the anomalous Raman peaks. Additionally, no sample exhibited the 175 cm$ ^{-1}$ Raman peak which is commonly attributed to MnTe$ _2$ . The aggressive surface oxidation and associated elemental Te formation in MnTe have important implications for any surface-sensitive and optical characterization of MnTe (and other similar Te-containing materials) involving even the briefest air exposure.
Materials Science (cond-mat.mtrl-sci)
10 pages, 5 figures, plus Supporting Information (8 figures, 1 table)
Surface-condition-mediated supercooling of the A-B transition in confined superfluid helium-3
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Daksh Malhotra, Aymar Muhikira, Alexander J. Shook, John P. Davis
Chiral $ p$ -wave superconductors and superfluids are central model systems in the search for topological quantum matter, but in reduced dimensions their properties are inseparable from the boundary conditions imposed by surrounding surfaces. Superfluid $ ^3$ He provides a uniquely clean, well-established spin-triplet $ p$ -wave condensate in which these boundary conditions can be engineered directly. Here, we use a fourth-sound Helmholtz resonator to study the A–B phase transition of $ ^3$ He confined to a $ 1.8,\mu$ m cavity after preplating the internal surfaces with $ \sim4$ atomic layers of $ ^4$ He. In contrast to our previous fourth-sound measurements, which showed no resolvable hysteresis in the transition temperature, the preplated device exhibits a clear separation between cooling and warming transition temperatures together with stochastic run-to-run variations. The hysteresis decreases toward the highest pressures studied, consistent with previous observations of the pressure dependence of $ ^4$ He-mediated quasiparticle boundary scattering. These results demonstrate that surface preparation can qualitatively modify first-order transition kinetics in confined $ ^3$ He, making boundary conditions an experimentally accessible control parameter for metastability and for future studies of reduced-dimension topological superfluid states.
Superconductivity (cond-mat.supr-con)
ALIGNN 2.0: A Unified Line-Graph Neural Network Framework for Materials Screening, Force Fields, Inverse Design, Spectroscopy, and Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Jaehyung Lee, Charles Rhys Campbell, Akshaya Ajith, Sergei V. Kalinin, Christopher Wolverton, Kamal Choudhary
Graph neural networks are central to materials property prediction and machine-learning interatomic potentials, yet their reliance on specialized graph libraries hampers portability and reproducibility, and property and force-field models have historically required separate graph pipelines. We present ALIGNN 2.0, a dependency-free, pure-PyTorch reimplementation of the Atomistic Line Graph Neural Network, with the line graph and its batching built from scratch, running on current-generation accelerators and unifying scalar, spectral, tensorial, per-atom, and force-field prediction behind a single graph, a combination that to our knowledge no existing framework provides. Comparing radius and k-nearest-neighbor (kNN) graphs, the wider kNN graph is more accurate for properties while the smoothly varying radius graph is required for energy-conserving molecular dynamics. On the JARVIS-Leaderboard, ALIGNN 2.0 leads on 26 of 30 single-property benchmarks against the original ALIGNN, with large gains for piezoelectric and dielectric maxima, exfoliation energy, moduli, and superconducting Tc. The LAMMPS- and OpenMM-compatible ALIGNN-FF matches leading universal potentials on the Matbench-Discovery and CHIPS-FF benchmarks at a small fraction of their parameters while scaling to hundred-thousand-atom cells. We further use ALIGNN 2.0 as the denoiser in a conditional crystal-diffusion model, where explicit line-graph message passing consistently lowers structural denoising loss. We also show, as work in progress, that an independently diffused, redundant bond-angle state is learnable but does not uniformly improve reconstruction or combine additively with the line graph. Finally, from a single relaxed structure the same framework reconstructs infrared, Raman, optical-dielectric, and neutron spectra in agreement with experiment and DFT, and drives frozen-phonon electron-microscopy image simulation.
Materials Science (cond-mat.mtrl-sci)
Pairing symmetry and superconductivity from long-range Coulomb interactions in the extended t-t’-t’’-Jz model for cuprates
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
We investigate the pairing symmetry of the ground-state phase diagram of an extended two-dimensional $ t$ -$ t’$ -$ t’’$ -$ J_z$ model, in which the first-, second-, and third-nearest neighbor electron hopping terms ($ t,t’$ and $ t’’$ ) and an anisotropic Ising-like antiferromagnetic interaction $ J_z$ are treated on the same framework. We find that the dominant pairing symmetry depends sensitively on the sign and magnitude of the hopping parameters $ t’$ and $ t’’$ , showing pure $ p$ -wave, pure $ d$ -wave, or coexisting pairing channels, highlighting the decisive role of these terms. We further explore the role of the long-range and short-range repulsive interactions in the formation of pairs and analyze the specific case of hole-doped cuprates. Our results indicate that repulsive interactions favors hole pair escaping of the stripe domains. Furthermore, pairing correlation calculations strongly suggest that repulsive Coulomb interactions drive reentrant superconducting behavior at experimentally observed underdoped regime ($ \delta\approx0.07$ to $ 0.15$ ), as in Neodymium-based cuprates.
Superconductivity (cond-mat.supr-con)
13 pages 13 figures
Radial dam breaks in a two-dimensional droplet bearing environment
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
F. Bristy, S. Chandramouli, G. A. Bougas, G. C. Katsimiga, P. G. Kevrekidis, S. I. Mistakidis
The controlled dynamical generation of radial dam break flows (DBFs) is demonstrated in two-dimensional droplet environments. These ultracold mixtures feature competing mean-field and quantum fluctuation effects and are initialized on a disk-shaped uniform density. Depending on the value of the latter, reflecting also the dominance of attractive or repulsive interactions, three dynamical response regimes are identified. At small densities a moving wavetrain of bright ring solitons is observed (dubbed ring DBF), at intermediate densities a ring kink-dispersive shock wave, while at large densities the flows encompass composite ring kink-rarefaction waves moving towards the center. The emergence of these patterns, whose formation would be prohibited in two-dimensional Kerr media due to wave-collapse, is rooted in the competition between attraction and repulsion inherent to droplet environments, modeled by the extended Gross-Pitaevskii equation. The characterization of the ensuing nonlinear waveforms is further corroborated by reduced models based on the cubic-quintic nonlinear Schrödinger equation. The different wave patterns emanating from dam break flows can be experimentally realized using current state-of-the-art ultracold atom experiments.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
13 pages, 9 figures
Portfolio-Based Constrained Multi-Objective Bayesian Optimization for Materials Design
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Sushant Sinha, Christofer Hardcastle, Robert Robinson, Shakti Prasad Padhy, Brent Vela, Douglas Allaire, Raymundo Arroyave
Materials discovery and design campaigns can be formulated as constrained multi-objective Bayesian optimization (CMOBO) problems, within which each experimental decision negotiates between two coupled but competing goals: discovering feasible candidates and refining the underlying Pareto front. Here we recast acquisition-function choice as an adaptive policy-selection problem over a portfolio of conventional and feasibility-focused acquisition functions. This was done using two controllers: UCB-Bandit, a modified UCB multi-armed bandit, and Agentic-Switch, a multi-agent decision system driven by a large language model (LLM). Both were evaluated against fixed-policy baselines in silico across five synthetic benchmark functions and two materials design case studies. The adaptive policies performed competitively in terms of both cumulative feasibility count and feasible hypervolume improvement, while each individual acquisition function performed well for only one metric, suggesting that adaptive policies are better suited for constrained materials science problems.
Materials Science (cond-mat.mtrl-sci), Machine Learning (stat.ML)
Universality of the $1/9$ Magnetization Plateau and Quantum-Disordered States in the Kagome Family $\mathrm{Cs_8AB_3Ti_{12}F_{48}}$ ($A=\mathrm{Rb},\mathrm{Li}$; $B=\mathrm{K},\mathrm{Na}$)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Prena Chaudhary, Asiri Thennakoon, Tommy Park, Hanru Wang, Leshan Zhao, Laurel Winter, Neil Herrison, Christina Hoffmann, Junghong H. He, Harald O. Jeschke, Hiroyuki Nojiri, Akira Matsuo, Koichi Kindo, Miwako Takahashi, Yukio Noda, Taku J. Sato, Shiyan Li, Hiroaki Ueda, Gia-Wei Chern, Seung-Hun Lee
The microscopic origin of the low-field $ 1/9$ magnetization plateau in spin-$ 1/2$ kagome antiferromagnets remains unresolved. Here, we show that chemical pressure reshapes the hierarchy of fractional magnetization plateaus in the titanium-based kagome family $ \mathrm{Cs_8AB_3Ti_{12}F_{48}}$ ($ A=\mathrm{Rb},\mathrm{Li}$ ; $ B=\mathrm{K},\mathrm{Na}$ ). High-field magnetization measurements up to 60 T reveal a robust $ 1/9$ plateau-like phase in the expanded $ \mathrm{Cs_8RbK_3Ti_{12}F_{48}}$ and $ \mathrm{Cs_8LiK_3Ti_{12}F_{48}}$ compounds, despite the absence of the conventionally more robust $ 1/3$ plateau. In contrast, compressed $ \mathrm{Cs_8LiNa_3Ti_{12}F_{48}}$ exhibits neither the $ 1/9$ plateau-like phase nor a quantum-disordered ground state. Specific-heat measurements and first-principles calculations show that lattice expansion preserves a frustrated, fully connected kagome exchange network and gapless quantum-disordered ground states, whereas compression reorganizes the exchange network into weakly coupled quasi-one-dimensional subsystems and induces successive magnetic transitions. These results demonstrate that the $ 1/9$ and $ 1/3$ plateaus need not share a common microscopic origin and suggest that the $ 1/9$ plateau may represent a more universal feature of frustrated spin-$ 1/2$ kagome magnetism.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Quantum Physics (quant-ph)
Hydrogen Reorganization in Hot Dense Ammonia
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Hydrogen is known to form stable compounds with a variety of simple molecular solids under high pressure. However, ammonia hydride has not been experimentally observed. Here, through a series of laser-heating diamond anvil cell (LHDAC) experiments, we observed the transparent ionic ammonia transformed into an opaque phase above 150 GPa and 1000 K. Raman spectroscopy reveals a pronounced structural change, accompanied by the emergence of two distinct asymmetric H$ _2$ vibrons ($ \nu_1$ and $ \nu_2$ ). A new ionic phase produced following thermally induced dissociation and hydrogen reorganization in hot dense ammonia. The combination of experimental results and first-principles calculations identify this phase as the theoretically predicted ionic $ P4_12_12$ phase of NH$ _7$ , which consists of NH$ _4^+$ , H$ ^-$ and H$ _2$ units. Our results suggest that the formation of ammonia hydrides follows a thermodynamic pathway distinct from those of other H$ _2$ -containing mixtures, revealing a new ionic transformation pathway driven by hydrogen reorganization in hot dense ammonia.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
5pages,4 figures
Grain Boundary Distortion Reorients the Local 4f Easy Axis and Splits Light from Heavy Lanthanides in Nd2Fe14B
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
The coercivity of rare-earth permanent magnets originates from the crystal field acting on localized 4f electrons, yet how grain boundaries modify the underlying single-ion Hamiltonian remains largely unknown. Here we determine the 4f crystal field in bulk and grain-boundary environments of Nd2Fe14B using embedded multireference electronic-structure calculations for the substitutional series Ce, Pr, Nd, Gd, Tb, and Dy. Grain-boundary distortion produces a crossover across the lanthanide series: the crystal field weakens by up to 36% for light lanthanides but strengthens by about 25% for heavy lanthanides, with Nd marking the crossover. The ground-state doublet of Dy becomes more isolated and axial, whereas Ce exhibits a collapsed low-lying excitation that suppresses anisotropy. The local easy axis rotates from the bulk c axis toward the basal plane, identifying grain-boundary sites as favorable nucleation centers for magnetization reversal. These results provide an atomistic basis for heavy rare-earth grain-boundary diffusion and furnish transferable single-ion parameters for spin-lattice simulations.
Materials Science (cond-mat.mtrl-sci)
Vestigial chirality from fluctuating loop currents on the kagome lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Yin Shi, Xuande Bu, Sheng Meng
Multicomponent order can melt in stages, leaving a composite order after its primary constituents become short ranged. We study this possibility for commensurate three-$ Q$ loop-current order on the kagome lattice. Large-scale cluster and parallel-tempering Monte Carlo simulations reveal direct and two-stage melting regimes in an effective fixed-amplitude sign model. In the latter regime, translation-sector domain walls proliferate before chirality-changing walls, restoring lattice translational symmetry while preserving long-range time-reversal-odd order. The primary $ M$ -point correlations are short ranged in this intermediate phase. The two-stage regime begins when the lowest-energy chirality-changing wall is only about $ 12$ –$ 13%$ more costly than a same-chirality translation wall. Finite-size scaling of a stable amplitude-resolved Ginzburg–Landau theory shows that the phase survives amplitude relaxation. Our results establish a quantitative domain-wall criterion for vestigial loop-current order and a fluctuation route to time-reversal symmetry breaking without long-range loop-current Bragg order. This separation provides a possible thermodynamic framework for time-reversal-odd responses recently reported above the critical temperature for conventional charge-density-wave ordering in kagome metals.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 5 figures
Viscoelastocapillary extensional De-Oh or VE-DeOh stringiness of unentangled polymer solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Characterization, control, and calibration of stringiness, the propensity to form long, thin, persistent threads, are key to the design and application of polymer solutions and formulations transferred to substrates by dropwise dispensing, jetting, spraying, or coating, and are used in manufacturing fibers, membranes, or spray-dried products. For Newtonian fluids, enhancing shear viscosity translates into increasing stringiness as can be easily perceived during dripping of water vs. sugar syrups or glycerol-water mixtures. In contrast, even polymer solutions with comparable shear viscosity can display a significant contrast in extensional rheology and apparent stringiness. However, there are no quantitative maps, formulas, or scales for stringiness, which motivates this study. In this contribution, we contrast the stringiness for a series of aqueous polymer solutions by determining the filament lifespan using dripping-onto-substrate (DoS) rheometry and filament length and lifespan in using dripping-into-air (DiA). We investigate the influence of polymer chemistry and molecular weight on stringiness and rely on DoS rheometry to characterize pinching dynamics and extensional rheology response. We show that an increase in stringiness correlates with steady, terminal extensional viscosity, and extensional relaxation time, respectively. Lastly, we provide a framework, which compares the stringiness of different polymer solutions through an extensional Ohnesorge-Deborah ($ Oh-De$ ) plot or $ Oh_E-De_E$ map, by computing the two dimensionless groups $ Oh_E$ using steady, terminal extensional viscosity and $ De_E$ using extensional relaxation time, respectively
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Quantum transport across normal-superlattice-normal graphene junctions: Fabry-Pérot interference, Hofstadter butterfly, and supersnake states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Che-Pin Hsu, Alina Mreńca-Kolasińska, Aitor Garcia-Ruiz, Szu-Chao Chen, Denis Kochan, Klaus Richter, Ming-Hao Liu
Electrostatic modulation of graphene provides a tunable route to engineering miniband structures. We perform quantum transport simulations on a gate-defined graphene superlattice junction, formed by confining a two-dimensional superlattice graphene (SGr) region between two normal graphene (NGr) regions. In the low-field regime at low carrier densities, robust Fabry-Pérot interference fringes emerge even in the unipolar regime due to Fermi-velocity renormalization in the SGr region. At stronger magnetic fields but only up to 3 T, the conductance map clearly reveals the Hofstadter butterfly spectrum. At intermediate fields, our finite-width transport simulations reveal a new type of snake state, the supersnake state, composed of alternating anomalous cyclotron arcs on the SGr side and conventional semicircular arcs on the NGr side, forming a weaving trajectory along the junction. The resulting conductance oscillations agree well with geometrical conditions derived from semiclassical cyclotron orbits. Our results demonstrate that gate-defined NGr-SGr-NGr junctions provide a versatile platform hosting multiple transport regimes within a single device architecture and can be generalized to other types of superlattices not restricted to graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 7 figures
Collective Symmetry and Criticality from Single-Component Fluctuations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Chunhao Guo, Zhe Wang, Zheng Yan
Symmetry plays a fundamental role in modern physics by guiding the classification of phases and the construction of effective theories of critical systems. Identifying collective symmetry remains challenging because tests based on preselected order parameters can overlook hidden components. A central goal is therefore to extract symmetry and critical information from a single accessible component. We pursue this goal using Lee–Yang zero ratios generated by a single ordering field. Unmeasured components shape the projected fluctuation distribution and hence the relative zero positions. Deep in a phase with spontaneous symmetry breaking, we show analytically that the zero ratios for an isotropic order parameter approach a parameter-free Bessel sequence fixed by the number of collective components. Near quantum criticality, fluctuations deform this distribution. The resulting ratio deviations and their finite-size coupling dependence carry additional critical information. We demonstrate these results with large-scale quantum Monte Carlo simulations of many-body systems with conventional and enlarged continuous symmetries. This approach provides quantitative access to collective symmetry and criticality without measuring every competing order.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
Fractional quantum spin Hall crystals from hidden density-wave order
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Matthew Shammami, Sudip Chakravarty
Broken symmetry and topology are distinct descriptions for how matter organizes itself. Here, we propose one gives rise to the other. A mixed singlet-triplet $ d$ -density wave, which is a particle-hole condensate, has a hidden bond order that breaks translation symmetry and generates a time-reversed pair of Chern bands, without producing conventional charge or spin density order. At fractional fillings with odd denominators, finite size exact diagonalization studies show how repulsive interactions can transform this symmetry-broken topological state into a fractional quantum spin Hall liquid. Its opposite chiralities produce a crossed response in which charge flux transports spin, and spin flux transports charge. The same setting also reveals what borders such a phase. Strong interspin coupling and increasingly dilute fillings favor charge order and make residual band dispersion decisive, while at half filling, the spin-decoupled limit gives a homogeneous correlated liquid with signatures consistent with the physics of a composite Fermi liquid.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages, 13 figures
Transport Relaxation Mechanisms in Bilayer Graphene: Effects of Pauli Blocking
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
We present a unified analytical treatment of carrier transport relaxation in bilayer graphene (BLG), including scattering by surface roughness, charged and neutral impurities, acoustic and optical phonons, and substrate polar phonons. The calculation is formulated within the low-energy two-band approximation using Fermi’s golden rule and the semiclassical Boltzmann transport equation. Closed-form expressions for the transport relaxation rates are derived and verified by numerical evaluation of the corresponding scattering integrals. Particular attention is given to Pauli blocking, whose influence becomes important under degenerate carrier conditions owing to the approximately parabolic low-energy dispersion and nearly constant density of states of BLG. We find that Pauli blocking modifies the relaxation rates in a mechanism- and energy-dependent manner for both suspended and substrate-supported BLG. For the parameters considered, neutral-impurity scattering provides the dominant contribution over a substantial energy range, while acoustic-phonon and charged-impurity scattering remain important competing mechanisms. Optical-phonon scattering is suppressed below its emission threshold, whereas substrate polar phonons provide an additional relaxation channel in supported BLG. Comparison with monolayer graphene and a conventional two-dimensional electron gas highlights the role of band dispersion, density of states, screening, and chirality in determining the distinct scattering behavior of BLG. These results provide analytical insight into the relative importance of the principal momentum-relaxation mechanisms and the role of Pauli blocking in BLG transport.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
26 pages, 5 figures
Sensitivity of Nucleation Thermodynamics and Kinetics to the Treatment of Long-Range Interactions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Fernanda Sulantay Vargas, Kimia Sinaeian, Amir Haji-Akbari
Nucleation rates are exponentially sensitive to the thermodynamic driving force and can therefore depend strongly on the treatment of long-range intermolecular interactions. Here, using the Lennard–Jones (LJ) system as a benchmark, we combine molecular dynamics (MD) simulations, jumpy forward-flux sampling (jFFS), and free-energy calculations to quantify the effect of potential truncation on melting thermodynamics, homogeneous crystal nucleation kinetics, and computational cost. Within the cutoff-radius range $ 2.5\sigma\le r_c\le 6\sigma$ , the melting temperature at zero pressure varies by approximately 11%, while the nucleation rate changes by approximately ten orders of magnitude. By invoking classical nucleation theory (CNT), we show that this pronounced kinetic sensitivity originates primarily from cutoff-induced changes in the chemical potential difference between the liquid and crystalline phases. Building on this observation, we develop a CNT-based framework for extrapolating finite-cutoff rates to the full-potential limit and for estimating the expected rate deviations at other cutoff radii and temperatures. These findings also provide a systematic basis for cutoff selection: the optimal cutoff should minimize computational cost while keeping the deviation from the full-potential rate within acceptable bounds. At $ kT/\epsilon=0.5$ , $ r_c=4\sigma$ provides a reasonable compromise according to these criteria. We further demonstrate that conventional homogeneous tail corrections do not offer a reliable alternative, as they cannot consistently account for the liquid, crystalline, and interfacial environments present during nucleation. Our findings highlight the need to specify and validate the truncation scheme as an integral component of force-field development in simulations of nucleation and other interfacial phase transitions within inhomogeneous environments.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
14 pages, 10 figures, 1 table
Crystallographic imperfections and exotic superconductivity of UBe$_{13}$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Andreas Leithe-Jasper, Markus König, Yusei Shimizu, Konstantin Semeniuk, Primož Koželj, Mitja Krnel, Paul Simon, Wilder Carrillo-Cabrera, Nazar Zaremba, Marcel Naumann, Ulrich Burkhardt, Thomas Doert, Yurii Prots, Alfred Amon, Elena Gati, Matthias Vojta, Yuri Grin, Elena Hassinger, Eteri Svanidze
The symmetry of the superconducting gap is related to the symmetry of the crystal structure. In unconventional superconductors, big changes of the critical temperature, critical field or even the gap structure can happen even for small perturbations of the lattice. In this letter, we use microstructuring to study aluminium-free crystals of UBe$ _{13}$ which are expected to be closer to “perfect” material than previously studied aluminium-grown single crystals. We compare the effect of minuscule imperfections on the value of the critical temperature and critical field, which, in the case of UBe$ _{13}$ , has drastic effects, supporting its unconventional nature. We conjecture that this likely arises from the oxidation state of uranium, which is sensitive to its crystal environment. Our findings suggests that uranium-based materials provide not only an excellent reservoir of new unconventional phenomena, but also a way to identify the gap symmetry of unconventional superconductors.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Accepted for publication in Physical Review B
Superconductivity at the metal-insulator phase boundary in a bulk nickelate at ambient pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Hyo-Bin Ahn, Xinglong Chen, Hong Zheng, Yu Zhang, Ramakanta Chapai, Yu Li, Arashdeep S. Thind, Robert F. Klie, Michael R. Norman, Ulrich Welp, J. F. Mitchell, Daniel Phelan
The discovery of superconductivity in nickelates has seeded a new field for exploring unconventional superconductivity in transition metal oxides. However, to date superconductivity has only been realized in thin films or under extreme pressure in the bulk. Here we report signatures of superconductivity at ambient pressure in bulk nickelate single crystals of (La1-xPrx)4Ni3O8 and (La1-xYx)4Ni3O8, whose crystal structure comprises interleaving trilayers of square-planar nickel oxide and fluorite-like spacer layers. The parent compound La4Ni3O8 exhibits an insulating ground state, where electrons order into intertwined, insulating charge/spin stripes. Substitution of smaller lanthanide ions disrupts this order, eventually leading to a metallic ground-state. We find that superconductivity emerges in a narrow window proximate to the insulator-metal phase boundary, where both metallic and charge-stripe phases co-exist. The observed low volume-fraction superconductivity is non-percolative, suggesting the prospect of filamentary superconductivity nucleated at the boundary between these phases. However, intergrowth defects that approximate the known infinite layer nickelates are observed in TEM, leaving open the possibility that superconductivity resides here rather than in the trilayer matrix. Remarkably, the electronic phase diagrams of both the Y and Pr series coincide when parameterized by the volume of the fluorite like spacer layers, revealing that this steric parameter profoundly modifies the nickel oxide trilayer electronic structure. Our results identify better understanding of the co-existence region between metallic and charge-ordered phases as a priority for expanding the range of bulk, ambient-pressure nickelate superconductivity and establish spacer-layer engineering as a design tool for exploring this regime of phase competition.
Superconductivity (cond-mat.supr-con)
Observation of Dyakonov-Perel-type magnon spin relaxation in uniaxial antiferromagnetic insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Qinwu Gao, Andi Cong, Bokai Liang, Meng Yang, Jingjing Liu, Lang Chen, Shiwei Wu, Ka Shen, Junxue Li
Long-distance transport of magnon spin currents in antiferromagnetic (AFM) insulators has attracted tremendous attention recently, however, the AFM magnon spin relaxation mechanisms remain elusive. Here, we report that the Dyakonov-Perel-type magnon spin relaxation mechanism governs the spin current transport along the easy axis in two prototypical uniaxial AFM insulators, Cr2O3 and alpha-Fe2O3. First, an over 450% enhancement of the first-harmonic nonlocal signal induced by a magnetic field is observed prior to the spin-flop transition, which can be well-interpreted by our model incorporating Dyakonov-Perel-type magnon spin relaxation. Secondly, we find that the magnon spin diffusion length in both crystals increases with magnetic field and saturates at fields above 0.8 T, consistent with our model. Finally, the temperature dependence of the zero-field magnon spin diffusion length in both AFM insulators can be qualitatively explained through our model. These findings are valuable for the development of low-dissipation antiferromagnetic spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Vortex-mediated spin current injection into two-dimensional superconductor NbSe2
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Meng Yang, Xiaolong Yin, Jingjing Liu, Yifeng Chen, Qinwu Gao, Hongxing Zhu, Danni Huang, Lang Chen, Shuo-Ying Yang, Junxue Li
Injection of pure spin current into superconductors remains a major challenge in superconducting spintronics. Previous studies have primarily focused on spin-polarized quasiparticles and spin-triplet supercurrents, while vortices, ubiquitous topological defects in type-2 superconductors, have been theoretically proposed as alternative carriers of spin angular momentum, yet direct experimental evidence is still lacking. Here, we report the vortex-mediated spin current injection in NbSe2/LiAl2Fe3O8(LAFO) bilayer, an Ising superconductor/ferrimagnetic insulator heterostructure. Under an out-of-plane temperature gradient and an in-plane magnetic field, the NbSe2/LAFO bilayer shows a pronounced thermoelectric peak near the upper critical magnetic field, which has the opposite sign to the conventional vortex Nernst signal observed in a single-layer NbSe2. The sign reversal suggests that the vortex flow induced by spin current injection is opposite to the flow driven by the temperature gradient, which is consistent with theoretical mechanisms including spin-vorticity transmutation and the inverse vortex spin Hall effect. By mapping the field temperature phase diagram, we reveal that the spin current injection occurs exclusively in the vortex liquid phase of NbSe2. Absence of the thermoelectric signal above the superconducting transition temperature further rules out the quasiparticle contribution. Our results establish vortices as efficient carriers of spin information in superconductors, opening a new route towards vortex-mediated superconducting spintronic devices.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
20 pages, 4 figures
Pressure induced structural phase transition and magneto-elastic coupling in Eu doped LaCrO$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Asish Kumar Mishra, Mrinmay Sahu, Bhagyashri Giri, Bidisha Mukherjee, Suvashree Mukherjee, Harekrishna Bhunia, Tamalkanti Mukherjee, Sujoy Ghosh, Partha Mitra, Peter Liermann, Goutam Dev Mukherjee
In this study, we have carried out a detailed high pressure investigation on 5$ %$ Eu doped LaCrO$ _3$ (ELCO) using synchrotron X-ray diffraction (XRD), micro Raman spectroscopy, and low-temperature magnetization measurements to correlate the structural and magnetic properties under pressure. The high pressure XRD reveals the orthorhombic to rhombohedral structural phase transition around 10.6 GPa. The high pressure Raman data corroborate this result and indicate that the lattice instabilities associated with the low-frequency soft modes play a crucial role in driving this transition. In addition, a pronounced anomaly in the Raman shift and integrated intensity of several Raman modes is observed around 4.5 GPa. By combining the low-temperature magnetization measurements with the anomalies observed in the XRD and Raman data and by comparing with the similar results in LaCrO$ _3$ (LCO), a pressure-induced change in the magnetic ground state to antiferromagnetic ordering is predicted.
Strongly Correlated Electrons (cond-mat.str-el)
Spontaneous filament formation and network self-assembly via active phase separation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Elena Lucas, Varun Venkatesh, Amin Doostmohammadi
We introduce Active Model H$ ^{-}$ , a scalar phase-field model of non-equilibrium phase separation in the overdamped hydrodynamic limit, and show that it produces filamentous networks with enhanced connections and arrested coarsening, a morphology not observed in existing scalar active field theories. Isolated filaments are unstable to spontaneous bending, and the resulting curvature drives self-propulsion towards the convex side, causing them to collide and assemble into a percolating network. The networks are locally non-equilibrium, with anomalously curved edges, disordered vertex angles and heterogeneous topological charge, yet recover Lewis’s law macroscopically. Under noise they show balanced break and reform dynamics.
Soft Condensed Matter (cond-mat.soft)
The Roadmap of Inorganic Computational Materials Databases: Capabilities, Credibility, Coverage, and the Open Frontier
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Miao Liu, Jianghao Jin, Tenglong Lu, Jianguo Si, Yin Shi, Sheng Meng, Weihua Wang
Computational materials databases have become central infrastructure for data-driven discovery of inorganic materials, yet their growth remains strikingly uneven across property families. This perspective synthesizes a systematic survey of mainstream density functional theory (DFT) software, the computational cost and credibility of nineteen material-property families, and the coverage of existing computational databases, into a coherent picture of where the field stands and where it should go. We show that the ecosystem of first-principles codes is methodologically mature: for nearly every property of technological interest, at least one production-grade code can compute this http URL binding constraint is no longer methodological capability but the economics of trust - which properties can be computed cheaply enough, and accurately enough, to be harvested at database scale. Mapping database coverage onto a Gartner-style readiness cycle reveals a sharp divide: ground-state structure, energetics, elasticity, and topology have reached routine production, while nine property families - including NMR/EPR parameters, core-level spectra, electron-phonon properties, thermal conductivity, and quantum transport - remain without any systematic computational database. We argue that these blank zones define the scientific opportunity of the next decade, and we propose a three-horizon roadmap: consolidating coverage and interoperability in the near term, industrializing mid-cost properties through surrogate-accelerated workflows in the medium term, and conquering the high-cost frontier through machine-learned interatomic potentials, autonomous computing infrastructure, and community governance in the long term.
Materials Science (cond-mat.mtrl-sci), Computational Engineering, Finance, and Science (cs.CE), Computational Physics (physics.comp-ph)
Generic thermodynamics of condensates with extremely small superfluid density —Application to UTe$_2$ and hidden second phase transition—
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Motivated by recent experimental findings on UTe$ _2$ via NMR and specific heat experiments, we theoretically explore the thermodynamic signatures of condensates with small superfluid density and characterize their physical properties. We identify the hidden superconducting phase $ A_2$ composed of spin-up Cooper pairs
at lower temperature ($ T$ ) and field ($ H$ ) under ambient pressure of UTe$ 2$ and show that $ A_2$ reappears at higher $ H$ for all three principal field directions, $ a$ , $ b$ , and $ c$ -axis. The phase transition lines from the $ A_1$ phase with spin down pairs to the $ A_2$ phase in the $ H$ -$ T$ plane are all horizontal in common, implying a universal physical origin due to the originating from the magnetic-energy gain of the spin-up pairing state with increasing magnetic field. This multiple-phase diagram is extended to these under pressure ($ P$ ), resulting in a simple picture based on non-unitary spin-triplet pairing symmetry $ ^3B{3u}$ , which enables us to consistently capture the evolution of the superconducting phases throughout the entire $ H$ -$ T$ -$ P$ phase space.
Superconductivity (cond-mat.supr-con)
43 pages, 15 figures
Orbital fingerprinting of magnetism across the Mn-Ni-Ga Heusler ternary
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Felipe Hawthorne, Daniela A. Damasceno, Raphael M. Tromer, Ronaldo R. Pelá, Cristiano F. Woellner
In Mn–Ni–Ga Heusler alloys, the competing magnetic states are separated by differences of a few meV per atom, so the ground state has to be resolved from the electronic structure and cannot be read off the composition. Moving away from the stoichiometric compounds, where the established rules for Heusler magnetism fall short, increases this difficulty. To overcome it, we introduce orbital fingerprints taken from the projected density of states, and use them as the input to machine-learning models for classification of the magnetic ordering, for the magnetic moment amplitude, for the spin polarization at the Fermi level and for interpolation of the phase diagram. The models are trained on a dataset of 370 spin-polarized first-principles calculations of quasirandom structures covering the ternary, which show good agreement with the magnetic ground states and lattice parameters available in the literature. For magnetic ordering, the top-ranked descriptor is the same quantity found by first-principles calculations to distinguish the phases, suggesting that the fingerprints capture the underlying physics.
Materials Science (cond-mat.mtrl-sci)
Machine Learning for High-Entropy Catalysts: Methods and Applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Hao Chen, Zongrui Pei, Xianglin Liu
High-entropy alloys (HEAs) exhibit exceptional catalytic performance in various reactions due to their high configurational entropy, synergistic elemental effects, tunable electronic structures, and excellent structural stability. However, the vast compositional space of HEA catalysts makes traditional experimental and theoretical design costly and inefficient. In recent years, data-driven machine learning (ML) methods have emerged as powerful tools for studying HEAs in catalysis. Through predictive models and ML surrogates, researchers can decipher the intricate composition-structure-performance relationships of these materials. In addition, by leveraging large language models (LLMs) for knowledge extraction, hypothesis generation and validation, and as a foundation to build integrated design workflows, ML approaches can significantly accelerate the design of novel HEA catalysts. This review systematically summarizes the latest methodological advances and applications of ML methods for HEAs in catalysis, discusses the challenges, and offers insights into future research directions to support the rational design and efficient development of catalysts.
Materials Science (cond-mat.mtrl-sci)
Tunable flat band on the surface of a rhombohedral kagome ferromagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Xinglu Que, Qingyu He, Lihui Zhou, Lilian Prodan, Vladimir Tsurkan, István Kézsmárki, Hidenori Takagi, Dennis Huang
A central goal in the exploration of kagome-based materials is the realization of a flat band that has meV bandwidth and lies close to the Fermi energy. The prevailing assumption is that band flattening originates from destructive hopping processes on the kagome lattice. We perform scanning tunneling microscopy (STM) on the layered kagome ferromagnet Fe$ _3$ Sn$ _2$ and show that it indeed hosts a flat band near the Fermi energy, which is manifested as a sharp peak in the differential tunneling conductance. First-principles slab calculations reveal, however, that this band is flattened not by the destructive interference of intralayer hopping, but by interlayer hopping between rhombohedral-stacked kagome planes in Fe$ _3$ Sn$ _2$ , and is confined to the surface layer. This surface band, forming in the vicinity of the Brillouin zone corners $ \bar{K}$ and $ \bar{K’}$ , exhibits rich magnetic-field dependence, including fine structure due to valley-symmetry breaking by rotated Fe moments, as well as a persistent diamagnetic shift associated with orbital magnetic moments, all reproduced by our calculations. Our results, highlighting the crucial role of layer stacking on the band structure of kagome magnets, demonstrate experimentally an alternative mechanism of generating magnetically tunable flat bands in atomically thin volumes of topological magnets.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 6 figures
Odd/Even or Half ? Entanglement Anomaly in the Bose-Hubbard model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
Humberto E. López-Hernández, Santiago F. Caballero-Benitez
The area law relates the bipartite entanglement entropy of a quantum many-body ground state to the size of the boundary between the subsystems, but the geometry of this boundary is rarely discussed. We inspect this in the 1D Bose-Hubbard model at fixed density by comparing four spatial bipartitions of the periodic lattice: first half, second half, even sites, and odd sites; sharing the same number of sites but differing in how the boundary is arranged. We find analytical limits with perturbation theory: in the Mott insulator the contiguous cut obeys the area lay while the alternating cut obeys a volume law $ S\propto N_s$ , in this sense an anomaly, and for the superfluid both cuts colapse to the binomial saturation due to delocalization of the state. We formulate these limits as a statement about the many-body problem using a generalized slave-boson approach based on mean-field with quantum fluctuations while verifying with Exact Diagonalization (ED) for small lattice sizes and Densitiy Matrix Renormalization Group (DMRG) simulations for $ N_s\gg 1$ . The slave-boson Gaussian ground state allows to compute the entanglement entropy from a reduced correlation matrix for any desired bipartition consistent with ED and DMRG results. Using slave bosons the computational cost is set by the local cutoff $ n_{\max}$ rather than the Hilbert space dimension, so we can reach lattice sizes far beyond ED. Our method is capable of establishing the partition-dependent scaling laws as a many-body feature, not only a finite-size effect, in great agreement with the ED for $ N_s\in[4,10]$ and DMRG for larger lattice sizes.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
7 pages, 2 tables, 3 figures and supplemental material with 9 pages, 3 tables and 4 Figures
Encounter Propagator for Multiple Targets: A Dirichlet-to-Neumann Spectral Formalism
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
We develop an encounter-based formulation of restricted diffusion in a bounded domain with multiple targets, resolving separately the boundary local time accumulated on each target. Unlike the single-target problem, the target projection operators do not generally commute with the governing Dirichlet-to-Neumann (DtN) operator, so that its eigenbasis does not diagonalize the local-time dependence. We overcome this difficulty by decomposing the DtN operator into target-restricted blocks. Multi-dimensional Laplace inversion then yields a convergent switching expansion, whose successive terms describe alternating diffusive transfers between the targets. We also derive an equivalent operator-valued renewal equation. For two targets, diagonalizing the target-restricted blocks provides an explicit spectral representation in terms of two DtN block spectra and an inter-target coupling matrix. When the coupling preserves spectral modes, the switching series can be resummed exactly in terms of modified Bessel functions. In general, as the off-diagonal DtN block is smoothing for separated targets, one can resort to low-rank finite-dimensional approximations. We examine an effective two-mode reduction for small, well-separated targets and identify a regime in which repeated inter-target transfers are progressively suppressed. Probabilistic interpretations and implications for diffusion-controlled reactions are discussed.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Numerical Analysis (math.NA), Spectral Theory (math.SP)
Fragmentation of Quantum Fluid in dipolar Bose-Einstein condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
In this article, we study the dipolar Bosonic quantum fluid. The fluid experiences mean-field, beyond mean-field, and three body interactions. We investigate their competition with dipolar interaction and fragmentation as a result of this competition. We further investigate the elementary excitations and note two distinct dispersion regimes, namely roton-mode and modulational instability. We support our observation by calculating the superfluid fraction and the condensate fraction.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
10 Pages, 8 figures
Anharmonic Phonon Renormalization and Defect Tolerance of the Thermoelectric Power Factor in Monolayer SnSe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Nguyen Tran Gia Bao, Thang Bach Phan, Vu Thi Hanh Thu, Nguyen Tuan Hung
Monolayer tin selenide (SnSe) exhibits phase-dependent anharmonic lattice dynamics, yet their consequences for the thermoelectric power factor (PF) and point-defect tolerance remain unresolved. We combine density functional theory, the stochastic self-consistent harmonic approximation (SSCHA), and Boltzmann transport calculations including electron-phonon and electron-defect scattering to investigate monolayer $ \alpha$ -SnSe (Pnma) and $ \beta$ -SnSe (Cmcm). In dynamically stable $ \alpha$ -SnSe, SSCHA renormalizes the finite-temperature phonons without changing the qualitative n-type transport picture. In $ \beta$ -SnSe, SSCHA removes the harmonic soft-mode instability of the Cmcm phase at 800-1000 K, and thereby enables high-temperature transport calculations; LO/TO-2 is the principal electron-scattering channel. In the lower-density window near $ 10^{12}$ cm$ ^{-2}$ , the n-type PF reaches 15-19 $ \mu\mathrm{W}/(\mathrm{K}^{2}\cdot\mathrm{cm})$ at 800-900 K and exceeds the p-type PF primarily because of the higher electrical conductivity. Se vacancies ($ V_{\mathrm{Se}}$ ) produce weaker electron-defect scattering than Sn vacancies ($ V_{\mathrm{Sn}}$ ), and p-type transport is less defect tolerant than n-type transport in both phases. We define an operational critical defect concentration, $ C_{\mathrm{crit}}$ , at which the PF decreases by 15% relative to the corresponding defect-free value. The lowest $ C_{\mathrm{crit}}$ is $ 8.841\times10^{-5}$ (approximately 88 ppm) for p-type $ \alpha$ -SnSe with $ V_{\mathrm{Sn}}$ ; for n-type $ \beta$ -SnSe with $ V_{\mathrm{Se}}$ , the 15% threshold is not reached up to $ 5\times10^{-3}$ (5000 ppm). These results distinguish finite-temperature phonon renormalization in stable $ \alpha$ -SnSe from anharmonic stabilization in $ \beta$ -SnSe and provide defect-concentration limits for preserving the PF.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
13 pages, 4 figures, 1 table
Corner entanglement scaling with projected entangled pair states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Chloé Van Bastelaere, Rui-Zhen Huang, Laurens Vanderstraeten
Entanglement scaling provides a powerful probe of universal properties at quantum critical points. In two dimensions, contributions originating from a corner-shaped bipartition exhibit a universal scaling, which is determined by the underlying conformal field theory. We develop a method to extract this corner entanglement entropy from projected entangled pair states directly in the thermodynamic limit. When applied to models at a quantum critical point, we show that the corner contribution exhibits scaling with the effective correlation length, in agreement with the hypothesis of finite-entanglement scaling. Our results for the corner coefficients are consistent with other methods, demonstrating the efficiency of our method for diagnosing strongly-correlated quantum critical points in two dimensions.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Statistical delocalization in the Anyonic Aubry-André model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
Andoni Agirre, André Eckardt, Tobias Grass
Many-body localization is remarkable in that localization persists despite the presence of dynamical interactions. Here we demonstrate the converse phenomenon: enhanced many-body delocalization induced solely by exchange statistics. We study a Aubry-André quasiperiodic system of anyons in one dimension in the absence of density-density interactions. In terms of anyon operators, the system is described by a quadratic Hamiltonian. By analyzing the finite-size scaling of its spectral properties and the inverse participation ratio of many-body eigenstates, we find that increasing the anyonic statistical phase systematically shifts the many-body localization crossover toward larger quasiperdiodic potentials. We further confirm these findings using a dynamical probe, namely the persistence of an initial density imbalance following quenches. Our results establish exchange statistics as an independent mechanism capable of altering many-body localization, revealing a fundamentally distinct route to delocalization in one-dimensional quantum systems.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
8+3 pages, 5+4 figures
Highly uniform first-electron position in qubit arrays fabricated on dedicated QSOI(R) 300mm commercial platform
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Johan Pelloux-Prayer, Elise Prin, Giselle A. Elbaz, Pierre-Louis Julliard, Amaryllis Comiti, Clément Nguyen, Sylvain Martin, Patrick Torresani, Renan Lethiecq, Carlos Augusto Suarez Segovia, Franck Arnaud, Etienne Nowak, Tristan Meunier, Bruna Cardoso Paz
We report progress toward the development of a quantum silicon-on-insulator (QSOI(R)) technology compatible with 300mm CMOS fabrication and adapted from the 28nm Fully-Depleted SOI (28nm FD-SOI) platform for scalable quantum computing. We compare quantum devices fabricated with standard 28nm FD-SOI and QSOI(R) technologies, and show striking improvements of room temperature electrostatic properties of the individual device. Moreover, the QSOI(R) technology has significantly reduced the device variability and the dispersion of device properties at the wafer level. Transistor metrics are reproduced by TCAD simulations showing that the electrostatics of the devices behave as expected for QSOI(R) technology. Wafer-scale measurements at sub-2K show reproducible quantum dots down to the few-electron regime with 69% yield for successful charge detection of the first electron and a dispersion of the first electron position of $ \mathrm{\pm 35 mV}$ over 377 quantum dots. These results establish QSOI(R) as a promising platform for CMOS-compatible quantum device co-integration.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Modeling Dynamic Magnetic Response of Spinel Soft Ferrites with the Steepest-Entropy-Ascent Quantum Thermodynamics Formalism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Deepak Dhariwal, William T. Reynolds Jr., Michael R. von Spakovsky
Selecting soft ferrites for alternating-field applications requires balancing magnetic response, dissipation, nonlinearity, and heating. We use a field-driven steepest-entropy-ascent quantum thermodynamic (SEAQT) model to compare the electron, phonon, and magnon responses of Fe$ _3$ O$ _4$ , MnFe$ 2$ O$ 4$ , and (Mn$ {0.5}$ Zn$ {0.5}$ )Fe$ _2$ O$ _4$ within a common first-principles framework. The model treats spatially uniform longitudinal relaxation and neglects domain-wall motion, transverse rotation, resonance, eddy-current effects, and heat removal. We use $ \tau_e=0.05$ ps and $ \tau_p=3$ ps for all three materials, with effective longitudinal magnon relaxation times of 500, 200, and 85 ps, respectively; these literature-motivated values are model inputs, not fits to measured losses. Within this framework, the Mn–Zn ferrite gives the largest peak longitudinal magnetization change, retains its response best at high frequency, and shows the largest work per cycle and peak-to-peak magnon temperature change, whereas MnFe$ _2$ O$ _4$ gives the largest normalized $ \chi’’$ peak. Thus, no single ferrite ranks highest across all metrics: the preferred material depends on the property, frequency, field amplitude, and cation configuration of interest. The model therefore provides a spectrum- and kinetics-resolved screening tool for engineering comparison of ferrites rather than a prediction of total core loss.
Materials Science (cond-mat.mtrl-sci)
When Is Kramers-Wannier Duality Invertible?
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Akash Sinha, Pramod Padmanabhan, Vladimir Korepin
{\it Kramers-Wannier} duality of the quantum Ising chain is naturally realized as a noninvertible transformation on a finite periodic chain. Upon incorporating appropriate symmetry-twisted sectors, however, the duality can be promoted to an invertible unitary transformation. In this Letter, we classify when the Kramers-Wannier duality admits an invertible realization on a finite Hilbert space. We show that this is determined by the representation of the Ising bond algebra and establish a necessary and sufficient condition in terms of its two central elements. This representation-theoretic criterion unifies the conventional noninvertible realization with invertible constructions involving symmetry-twisted sectors and applies equally to other models with the same underlying bond algebra. As an explicit example, we find an order-disorder duality in a non-trivial realization of the Ising bond algebra that admits an invertible Kramers-Wannier duality.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
7 pages
Type-I superconductivity in a quasi-2D topologically nontrivial YbBi$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Karolina Górnicka, Sudip Malick, Joanna Bławat, Michał Modrzejewski, Hanna Świątek, Michał J. Winiarski, Federico Mazzola, Ivana Vobornik, Chiara Bigi, Jacob Cook, Brenden R. Ortiz, Andrew F. May, Andrzej P. Kądzielawa, John Singleton, Bartlomiej Wiendlocha, Tomasz Klimczuk
Intrinsic superconductivity in stoichiometric materials with nontrivial electronic topology remains uncommon, limiting opportunities to investigate how these two phenomena coexist within a single electronic system. Here, we report bulk type-I superconductivity below $ T_c$ $ \sim$ 0.9~K in YbBi$ _2$ , a layered rare-earth compound with a nonsymmorphic crystal structure and a quasi-two-dimensional Fermi surface. Thermodynamic and transport measurements establish the superconducting ground state, while quantum oscillations reveal exceptionally light carriers, with a cyclotron mass as low as 0.07 $ m_e$ , and a nonzero Berry phase of approximately 0.82 $ \pi$ . The latter closely matches the calculated value of the corresponding Wilson phase 0.99 $ \pi$ for the corresponding orbit near a symmetry-protected band degeneracy. ARPES measurements show good agreement with key features of the calculated electronic structure, providing complementary experimental constraints on the normal-state band structure. The combination of intrinsic type-I superconductivity, light quasi-two-dimensional carriers, and signatures of nontrivial electronic topology identifies YbBi$ _2$ as a distinct stoichiometric platform for investigating superconductivity in a topologically nontrivial electronic environment.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
11 Pages, 5 Figures
Coherent antiferromagnetic resonance in MnO driven by impulsive terahertz excitation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Yinchuan Lv, Martin J. Cross, Hari Paudyal, Christopher T. Parzyck, A. H. M. Reid, Durga Paudyal, Matthias C. Hoffmann
Antiferromagnets (AFMs) offer a promising platform for ultrafast information processing owing to their intrinsically fast spin dynamics and vanishing net magnetization. Realizing this potential, however, requires understanding how terahertz fields excite coherent magnons and how the resulting spin motion is transduced into an optical signal. Here we report impulsive terahertz (THz) excitation and time-domain detection of the antiferromagnetic resonance (AFMR) in single-crystal manganese(II) oxide. Time-resolved birefringence measurements reveal long-lived coherent spin oscillations in the AFM phase. The resonance softens and becomes strongly damped upon warming toward the Néel temperature. Despite this similar excitation behavior, the detected birefringence in MnO is markedly weaker than in NiO. We associate this suppressed optical visibility with the weak spin–orbit-mediated magneto-optical coupling of orbital-singlet, high-spin Mn$ ^{2+}$ . These results demonstrate that coherent magnon excitation and its optical detection are governed by distinct microscopic interactions.
Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures
Higher-Order Interactions in Complex Systems: Mechanisms, Behaviour, Representation and Reducibility
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Higher-order interactions couple three or more elements in ways that cannot be decomposed into pairwise contributions. In diverse complex systems they produce striking collective behaviours such as explosive synchronization, discontinuous transitions and altered stability. Neither such behaviour nor a description written in many-body terms establishes a many-body mechanism, since both depend on how the system is represented. This review distinguishes three questions: what mechanism governs the system, what behaviour does it produce, and how is either represented? Representation covers both which variables are included and how relations among them are encoded. We examine direct many-body mechanisms, nonlinear but pairwise mechanisms that mimic them, and indirect routes through shared environments or eliminated variables, together with temporal aggregation, an artefact of observation rather than a mechanism. The same behaviour can arise from different mechanisms, and a given higher-order mechanism has no universal behavioural consequence. We then formulate reducibility, the question of whether a higher-order model can be replaced by a lower-order one, as a comparison between a source model and an admissible class of lower-order models, relative to a target and a tolerance. The target may be a microscopic rule, an observable or a qualitative feature. Information-theoretic and inferential methods are reviewed as complementary tools for detecting higher-order dependence, testing lower-order alternatives and reconstructing interaction structure. However, observational data alone generally cannot establish the mechanism. We close by identifying open problems in linking mechanisms to measurable signatures, coarse-graining, identifiability and causality, and in extending reductions beyond mean field. (Abridged)
Statistical Mechanics (cond-mat.stat-mech)
30 pages, 1 figure, 1 table, review paper
Landau diamagnetism and the de Haas-van Alphen effect from a single geometric construction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Landau diamagnetism is usually derived from the grand canonical potential, a calculation that yields the correct susceptibility but little physical insight, while the rule that extremal cross sections govern the de Haas-van Alphen (dHvA) oscillations is commonly asserted rather than exhibited. We present an elementary zero-temperature construction in which the occupied states of a free-electron gas are grouped, interval by interval along the field direction, into the Landau levels onto which they condense. Within each interval the field-induced energy cost reduces to a transfer of states between two congruent triangles, and center-of-mass arithmetic yields the Landau susceptibility. The construction fails only in a narrow neighborhood of an extremal cross section of the Fermi surface; there the contribution oscillates with the dHvA period, one oscillation for each Landau level that passes through the extremal cross section. Direct zero-temperature state counting locates the oscillation: the residual is concentrated in the few intervals nearest the extremal cross section, the summed contribution of the distant ones being negligible on the scale of the peak oscillation amplitude.
Statistical Mechanics (cond-mat.stat-mech)
7+2 pages, 3+1 figures
J. Kor. Phys. Soc. (2026)
Plasmons in twisted bilayer graphene across dispersive and flat bands
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Antonio Palamara, Michele Pisarra, Antonello Sindona
The dynamical dielectric response of twisted bilayer graphene is explored in large-angle dispersive-band and small-angle quasi-flat-band regimes using time-dependent density-functional theory within the random-phase approximation. At the reference bilayer-graphene interlayer distance, weak coupling in the largest-angle structures preserves Dirac dispersions and the intrinsic $ \pi$ plasmon. Electron doping activates a two-dimensional Dirac plasmon with energies obeying approximate geometric twist-angle scaling, while acoustic-like branches remain embedded in the single-particle continuum. The prohibitively large first-magic-angle supercell is represented by a tractable cell with its interlayer separation reduced to the angle-dependent magic distance, where four quasi-flat bands emerge around the Fermi level. Their partial occupation produces a dispersive low-energy plasmon-like excitation without a clear dielectric zero at resonance. A distinct interband plasmon is instead identified, supported by transitions involving the quasi-flat manifold and neighboring high-density-of-states regions. Band-energy rescaling places its characteristic energy in the mid-infrared range of interband collective excitations measured near the magic angle.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Reconfigurable Current Distributions in Percolating Au Films and CrO2 Powder Compacts - Beyond Geometrical Connectivity
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-18 20:00 EDT
E. Yu. Beliayev, I. G. Mirzoiev, V. A. Horielyi
Despite fundamental differences in morphology, dimensionality, and microscopic transport, semicontinuous Au films and compacted CrO2 powders converge on a common network-level principle: the electrically relevant network is a condition-dependent subset of the physical contact network. In Au films near the geometrical percolation threshold, increasing bias reversibly shifts the low-temperature response from activated nearest-neighbour hopping with negative magnetoresistance to a weak-localization-like regime with positive magnetoresistance, consistent with broader electronic participation of the fixed island network. In CrO2 powder compacts, magnetic field mainly changes the spin-dependent resistances of existing intergranular junctions and thereby reorders competing current paths; temperature and measuring current can additionally expand or deplete the active network. Cohn’s theorem provides a compact sensitivity principle for both cases: local resistance changes influence the measured response in proportion to the current carried by the affected links. The comparison identifies two limiting but interconvertible modes of reconfiguration - link enabling and link reweighting - and shows why geometrical connectivity alone is insufficient for interpreting transport in strongly inhomogeneous conductors.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
7 pages
Hubbard models with ultracold shielded molecules in optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
Kevin Pérez, Joseph W. Desroches, Kaden R. A. Hazzard, Tijs Karman
We show that, in appropriate regimes, ultracold collisionally shielded molecules in an optical lattice realize a controlled extended Hubbard model, despite their large-radius hard-core repulsion. We compute the Hubbard parameters and show lattice depth and microwave-induced dipolar interactions provide flexible, independent control of on- and off-site interactions. This makes shielded molecules a powerful platform for extended Hubbard models and enables an interaction microscope that can distinguish inter-hole interactions in doped Mott insulators - crucial to superconductivity and strange metallicity - that are indistinguishable with quantum gas microscopy alone.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Chemical Physics (physics.chem-ph), Quantum Physics (quant-ph)
The hypoexponential form for the fiber-length distribution in thermoplastic composites revisited: finite initial length, cascade fracture, and its mechanistic status
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
In a previous work [Masubuchi et al., Compos. Sci. Technol. 134, 43 (2016)], a fiber-length distribution function was proposed as the hypoexponential, or Erlang-type, convolution of two exponential waiting lengths, motivated by two independent Poisson processes for breakage and for blocking of adjacent breaks. The present paper further evaluates this hypoexponential form by introducing a finite initial length L_{0}, and by analyzing the mechanistic basis of the buckling-induced fiber breakage process. The obtained finite-L_{0} closed-form solution was compared to a glass fiber dataset to retroactively justify the infinite-length idealization in the earlier work for such systems while providing the complete form for processes in which fragments remain comparable to L_{0}. Concerning the mechanics of fiber fragmentation, a Mellin transform analysis of the fragmentation equation showed that scale-invariant cascades yield power laws and therefore cannot generate characteristic lengths; those lengths must instead arise from scale-breaking ingredients, particularly the cutoff region and the arrested processing history. Monte Carlo simulations of a phenomenological finite-opportunity cascade showed that the hypoexponential form does not reproduce the peak of the generated distribution but captures its exponential-like tail, implying that it serves as a useful two-parameter fitting model, although not an exact generative distribution.
Soft Condensed Matter (cond-mat.soft)
22 pages, 3 figures
Divergent Solid-state Conversion Pathways in Evaporated All-perovskite Tandem Solar Cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Huagui Lai, Amber Wright, Nick Huber, Niels Uythoven, Federico De Giorgi, Jincheng Luo, Tristan Sachsenweger, Sunil B. Shivarudraiah, Chih-Jen Shih, Wolfgang Tress, Fan Fu
Sequential thermal evaporation (sTE) is emerging as a solvent-free route to high-quality mid-bandgap perovskites, but its extension to mixed-halide wide-bandgap (WBG) and Sn-Pb narrow-bandgap (NBG) absorbers for all-perovskite tandem solar cells (TSCs) remains limited by an incomplete understanding of solid-state conversion. Here, using time-sliced ex situ analysis, we reveal divergent solid-state conversion mechanisms in sequentially evaporated WBG and NBG precursor stacks. In WBG stacks, formamidinium (FA)-containing species penetrate the inorganic template and Br/I redistribution precedes substantial three-dimensional perovskite formation. The photoactive phase then crystallizes from a chemically mixed reservoir, and absolute PbBr$ _2$ thickness, rather than nominal PbBr$ _2$ /PbI$ _2$ ratio, determines the final bandgap. In NBG stacks, by contrast, an early Pb-rich perovskite phase forms upon formamidinium iodide deposition, restricting further FA penetration into the buried SnI$ _2$ precursor. Subsequent annealing promotes rapid lattice reorganization faster than Sn/Pb interdiffusion, leaving vertical compositional gradients. Guided by these insights, we develop sTE absorbers with bandgaps spanning 1.26-1.96 eV and demonstrate the first evaporated all-perovskite TSC, reaching a power conversion efficiency of 19.2%. Encapsulated tandems retain on average 80% of their initial efficiency after 1,200 h at 65 $ ^\circ$ C (ISOS-D-2). These results establish bandgap-specific control of solid-state conversion as a design principle for sequentially evaporated perovskite tandem photovoltaics.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
54 pages (main text: 20 pages, 5 figures; Supplementary Information: 34 pages, 30 figures, 2 tables)
Superconductivity in Pb2-xBixPd Single Crystals
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-18 20:00 EDT
Chemical substitution provides an effective route to tune the structural and superconducting properties and to explore the evolution of superconductivity across related materials. In this work, we investigate the effect of Pb/Bi mixing on superconductivity in possible topological superconductors \ch{Pb2Pd} and $ \beta$ -\ch{Bi2Pd}, by synthesizing and characterizing single crystals of \ch{Pb_{2-x}Bi_{x}Pd} ($ 0.2\le x\le1.8$ ). Increasing Bi content triggers a structural phase transition from non-symmorphic ($ I4/mcm$ , $ x<1$ ) to layered ($ I4/mmm$ , $ x\ge1$ ) and induces a monotonic expansion of the lattice parameters. Across the doped range, all superconducting samples behave as weakly-coupled type-II superconductors exhibiting isotropic s-wave superconducting gaps.
Superconductivity (cond-mat.supr-con)
10 pages, 5 figures
Inferring interactions between active particles using harmonic traps
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Arnaud Compagnie, Joscha Mecke, Ivo Buttinoni, Hartmut Löwen
Quantifying the interactions between active Janus particles remains a challenge that needs to be addressed to describe their collective behaviour. Inspired by a photonic force microscopy setup where two active Janus particles are confined in separate optical tweezers, we derive the steady-state probability distribution of each particle bearing signatures of the pair phoretic interaction, which can be generalised to a broader range of interactions. This approach allows us to infer interaction forces and torques from positional configurations without any knowledge of the particle orientations. Unraveling the distance-dependent interaction between active particles is essential to harnessing them as building blocks for advanced materials with dynamic properties.
Soft Condensed Matter (cond-mat.soft)
A Computational Method to Simulate Electrostatic Actuation in Polycatenated Architected Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Mateus Maciel Vivaldi, Alexandre F. Fonseca
A novel class of polycatenated architected materials (PAMs) has recently emerged, exhibiting distinctive mechanical properties such as stress-strain hysteresis and a geometry-driven transition between solid-like and fluid-like behavior. Although finite element models exist for conventional PAMs, none currently account for electrostatic effects. Here, we propose and qualitatively validate a computational framework to simulate the structure, dynamics, and mechanical response of electrostatically charged PAMs. Our approach successfully reproduces electrostatic actuation in close agreement with experiments, and reveals that electrostatic charges enable a reversible fluid-to-solid transition while also providing a means to estimate electrostatic stiffness. Notably, stiffness enhancements of up to sevenfold are achieved upon charging. This work expands the design space of PAMs and offers a predictive tool for actively controllable mechanical metamaterials.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Conference paper, 3 figures, 1 table, 9 pages
Pressure-induced electronic and structural evolution of EuIrGe3
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
N.S.Dhami, V. Baledent, I. Batistic, C. M. N. Kumar, D. Kaczorowski, L. Nataf, J. M. Ablett, J.-P. Rueff, J. P. Itie, P. Fertey, S. R. Shieh, P. Popcevic, Y. Utsumi Boucher
We investigated the pressure-induced evolution of the electronic and crystal structure of the noncentrosymmetric BaNiSn3-type antiferromagnet EuIrGe3 using x-ray absorption spectroscopy, synchrotron x-ray diffraction complemented by density functional theory calculations, and electrical resistivity measurements. The Eu L3-edge spectra reveal a continuous increase in the mean Eu valence under compression, accompanied by modifications of the Ge and Ir electronic states. High- pressure x-ray diffraction shows anisotropic lattice compression in the tetragonal (I4mm) phase and provides evidence for a structural phase transition above 38 GPa. The experimentally deter- mined lattice and equation-of-state parameters are in good agreement with the DFT calculations. Electrical resistivity measurements reveal a monotonic increase in the antiferromagnetic ordering temperatures up to 18 GPa, indicating that the antiferromagnetic ground state remains robust despite the increasing contribution of the nonmagnetic Eu3+ configuration to the intermediate va- lence state. These results demonstrate that EuIrGe3 exhibits a pressure response distinct from EuCoGe3 and EuRhGe3, highlighting the important role of the transition metal d-electron states in the pressure-induced electronic and structural evolution of the EuT Ge3 family
Strongly Correlated Electrons (cond-mat.str-el)
7 Figures, 10 Pages
Predictive Structure to Thermal Conductivity Modeling Framework for BEOL Interconnect Stacks in Advanced Technology Nodes Enabled by Extensive Layer Resolved Thermal Measurements
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Zifeng Huang, Yiyang Sun, Tianyu Jia, Runsheng Wang, Zhe Cheng
The increasing structural complexity of BEOL interconnect stacks in advanced integrated circuits demands a structure-aware thermal conductivity (\k{appa}) modeling framework. However, generalizable models derived from layer-resolved thermal measurements that quantitatively capture the dependence of \k{appa} on interconnect structures remain lacking, limiting predictive thermal analysis. Here, we establish an experimentally derived, structure-aware \k{appa} modeling framework enabled by time-domain thermoreflectance measurements with ~100 nm depth resolution. Statistical analysis of a compiled dataset comprising over 40 experimentally measured layer-resolved \k{appa} values across diverse BEOL layers reveals a generalizable empirical structure-to-\k{appa} relationship, enabling predictive modeling based on interconnect structure. An intra-layer three-dimensional \k{appa} distribution model based on effective medium theory and realistic layouts further resolves spatial \k{appa} variations within practical interconnect layers. Together, these models establish an experimentally derived, structure-aware \k{appa} modeling framework for predictive and generalizable thermal analysis of advanced interconnect stacks and 3D ICs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Ultralow-Tensile Strain Enables Exciton Funneling and Energy Transfer to Boost MoSe2 Photoluminescence Quantum Yield
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Gayatri, Mehdi Arfaoui, Debashish Das, Mateusz Raczyński, Marta Bilska, Piotr Tatarczak, Aleksandra Krystyna Dąbrowska, Tomasz Kazimierczuk, Takashi Taniguchi, Kenji Watanabe, Piotr Kossacki, Andrzej Wysmołek, Saroj Kumar Nayak, Adam Babiński, Johannes Binder, Maciej R. Molas, Arka Karmakar
Strain engineering is a powerful route for controlling the exciton dynamics in van der Waals (vdW) heterostructures (HSs). The interlayer energy transfer (ET) process is another key factor in controlling the photocarrier relaxation pathways in vdW HSs. In this work, we combine these two processes to achieve an 8-fold enhancement to the relative photoluminescence (PL) quantum yield (QY) in a HS formed from monolayers of ReS2 and MoSe2, separated by a thin hBN interlayer, placed onto an hBN bubble. We achieve this enhancement by applying only 0.1% biaxial tensile strain, which results in efficient exciton funneling and an increased transition dipole moment. Our experimental data are supported by first-principles density-functional theory and coherent transfer-matrix method calculations, ruling out optical interference as the dominant origin of the enhancement. This work provides an innovative route for enhancing the PL QY of vdW materials via interplay between the tensile strain and the ET process.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Universal 1/f Noise in the Power Spectra of Energy Time-series in Solvated DNA Dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Harsh Sahu, Deepika Sardana, Pramod Kumar, Ajay Kumar Chand, Sobhan Sen, Sanjay Puri
We investigate energy fluctuations of solvated DNA in three conformations: G-quadruplex, Hairpin, and Duplex. Our comprehensive molecular dynamics (MD) simulations demonstrate that the time-series of interaction energies for DNA self, DNA-water and DNA-ion show 1/f noise with a universal decay exponent $ \beta \simeq 0.90$ . We show that DNA topology and structural rigidity modulate its dynamic coupling with the surrounding hydration shell and mobile counter-ions. This coupling critically shapes the 1/f noise profile: DNA self energies in flexible structures (G-quadruplex, Hairpin) display pronounced low-frequency modes absent in the rigid Duplex. These findings reveal how the interplay between DNA topology and environmental coupling governs different stochastic behavior in biologically relevant forms of DNA.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
Coplanar Lateral Gating MoS2 on SrTiO3: A Unified Platform for Classical and Quantum Devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Prasad Muragesh, Manav Murali, Venkatesha Modur Ramachandra, Madhu Thalakulam
Atomically thin transition-metal dichalcogenides, such as MoS2, offer a promising route to surpass the scaling limits of silicon owing to their excellent electrostatic control and resilience to short-channel effects. Realizing this potential depends critically on gate-stack engineering, where strong gate coupling must be achieved without compromising the pristine two-dimensional interface. Here, we demonstrate a coplanar lateral-gating architecture for MoS2 field-effect transistors fabricated directly on single-crystal SrTiO3. The exceptionally high permittivity of SrTiO3 enhances gate-channel coupling. The coplanar geometry eliminates the need for a separate gate insulator, reducing interface disorder. Owing to the quantum paraelectric nature, the SrTiO3 dielectric constant increases upon cooling, enhancing the gate coupling, leading to a decrease in threshold voltage and subthreshold swing an effect that contrasts with conventional FET architectures. The dielectric-free MoS2 surface, combined with enhanced electrostatic control, makes this architecture a promising platform for low-power two-dimensional electronics and cryogenic quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Emergent Surface Kondo Flat Band Driven by Competing Interactions in a Topological Ferromagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Nazar Zaremba, Susmita Changdar, Haojie Guo, Iñigo Robredo, Daniel Lozano-Gomez, Andreas Leithe-Jasper, Rui Lou, Yurii Prots, Mitja Krnel, Markus König, Konstantin Semeniuk, Berit H. Goodge, Yuri Grin, Andrii Kuibarov, Oleksandr Suvorov, Alexander Fedorov, Adam Pikul, Ivan Soldatov, Rudolf Schäfer, Bernd Büchner, Oksana Kvitnitskaya, Yurii Naidyuk, Louis Lamm, Meike Pfeiffer, Elena Hassinger, Matthias Vojta, Sergey Borisenko, Miguel M. Ugeda, Jeroen van den Brink, Eteri Svanidze, Maia G. Vergniory
A central goal of modern condensed matter physics is to uncover new quantum states of matter arising from the intertwined effects of strong electron correlations, magnetism, and band topology. Heavy-fermion phases, generated by Kondo interactions, represent one of the most remarkable manifestations of electronic correlations, and topological heavy-fermion states have been identified in several non-magnetic materials. Yet, the consequences of their competition with magnetic order have remained largely unexplored. Here, we reveal a new phenomenon: the spontaneous spatial separation of correlated quantum phases. By showing that magnetism can drive distinct strongly correlated electronic states to coexist in different regions of a single material, our work establishes a previously unknown mechanism for organizing quantum matter and opens a new direction in the study of correlated topological systems. Using \emph{bulk-sensitive} probes, we show that UAsS crystals are, in the bulk, metallic ferromagnets with only moderate correlation-driven band renormalizations. First-principles calculations reveal a topological electronic structure hosting both nodal lines and Weyl points, pointing to a rich underlying topology. Angle-resolved photoemission spectroscopy (ARPES) measurements are consistent with these predictions, resolving the nodal lines and Weyl crossings. In striking contrast, \emph{surface-sensitive} ARPES and scanning tunneling microscopy/spectroscopy (STM/STS) measurements reveal a pronounced flat band pinned at the Fermi level, accompanied by a sharp resonance – hallmarks of an emergent, strongly correlated Kondo state not captured by first-principles calculations.
Strongly Correlated Electrons (cond-mat.str-el)
Khinchin’s ergodicity and typicality in statistical mechanics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Dario Lucente, Marco Baldovin, Giacomo Gradenigo, Angelo Vulpiani
The formulation of statistical mechanics in terms of ensembles, originally proposed by Gibbs, has proved to be extremely effective in describing the equilibrium state of many-particle systems, in the most diverse contexts (critical phenomena, quantum mechanics, biophysics, just to mention a few). The reasons of this success are still debated, and the connection between dynamics and probability in large systems remains somehow elusive. Indeed, in order to derive the main results of equilibrium statistical mechanics, strong assumptions on the ergodicity of the dynamics are usually required. Nonetheless, empirical observations seem to suggest that the predictions of the theory hold true even when such assumptions are not verified. In this paper we reconsider the point of view put forward by Khinchin, stating that the only relevant ingredients for the validity of statistical mechanics are the large number of degrees of freedom in the system and the choice of extensive observables, irrespectively of the details of the microscopic dynamics. In particular, the presence of dynamical chaos is not required. To this aim, we discuss some analytical and numerical results on a couple of classical integrable systems, the harmonic chain and the Toda model, showing that many important features predicted by equilibrium statistical mechanics, as for instance Maxwell-Boltzmann distribution, are found even in absence of chaos.
Statistical Mechanics (cond-mat.stat-mech)
12 pages, 7 figures
Philosophical Transactions of the Royal Society A (2026)
Non-Thermal Effects in Fermionic Atoms Coupled to Open Cavities
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
We study a Fermi-Hubbard model coupled to a open dissipative single cavity mode. Using Keldysh diagrammatics we derive and solve the quantum kinetic equations for the fermions, taking the bosonic cavity mode as a source of non-equilibrium noise and dissipation. In absence of Hubbard interactions we show that the fermions reach generically a non-equilibrium steady-state, characterized by a non-thermal distribution function. Quite interestingly we demonstrate that the latter exactly nullifies the heat-current between fermions and cavity mode. We discuss the regimes of parameters where a low-frequency effective temperature description emerges and how the fluctuations affect the mean-field phase diagram for the superradiance phase transition. Finally we include Hubbard interaction in the weak-coupling regime and show that it leads to a crossover towards a full equilibrium distribution.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas)
Disorder-induced modulation of the nonlinear Hall effect in Weyl semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Juan A. Cañas, Daniel A. Bonilla, A. Martín-Ruiz
We study the effects of impurity scattering on the nonlinear Hall response of Weyl semimetals within the semiclassical Boltzmann approach. We derive the rectified and second-harmonic conductivity tensors for a general momentum-dependent transport relaxation time and evaluate this quantity microscopically for short-range, Gaussian, screened Coulomb, and magnetic impurities. For scalar disorder, the relaxation time is isotropic and chirality independent. The nonlinear Hall response is then determined by the anomalous velocity associated with the Berry curvature, and a finite net response requires energetically inequivalent Weyl nodes to avoid cancellation between opposite chiralities. Polarized magnetic impurities lead to a qualitatively different behavior. We find that interference between the first- and second-order Born amplitudes generates a helicity-dependent anisotropic correction to the relaxation time. This anisotropy changes the tensor structure of the nonlinear Hall conductivity and gives rise to a finite second-harmonic current for suitable orientations of the electric field relative to the impurity polarization. For representative parameters, however, the anisotropic contribution is several orders of magnitude smaller than the dominant isotropic response. These results establish how the microscopic form of impurity scattering enters the nonlinear Hall response of Weyl semimetals through the transport relaxation time.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
10 pages, 2 figures
Collective Charge-(2e) Bosonic Excitations in Charge-Ordered Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Charge order is conventionally characterized by a static modulation of the electronic density, while its collective excitations remain less developed from a quasiparticle perspective than those of spin-ordered systems. Here, we formulate the collective excititations of charge order within an effective charge-pseudospin model, in which the charge-ordered ground state is represented by staggered pseudospin order. Quantizing fluctuations around this ordered state via a Holstein–Primakoff transformation, we reveal two branches of bosonic quasiparticles with degenerate, gapped dispersions that carry opposite quantized electric charges $ \pm 2e$ . We therefore term these charge-$ 2e$ bosons ``\textit{bichargons},’’ closely paralleling the two magnon branches of a bipartite antiferromagnet that carry opposite spin angular momenta. We show that a temperature gradient drives the diffusion of thermally excited bichargons, generating a charge Seebeck response when the degeneracy between the oppositely charged branches is lifted by tuning the chemical potential away from the charge-neutrality point. In contrast, despite carrying finite electric charges, a thermal bichargon gas remains electrically insulating under a static electric field because bichargon quasiparticle number is not conserved. An ac electric field, however, can parametrically generate coherent pairs of oppositely charged bichargons that support a finite dc drift current in the presence of a bias electric field, offering a bosonic analogue of photoconductivity mediated by photoexcited electron–hole pairs in semiconductors. Our results establish bichargons as a new class of collective bosonic charge carriers in charge-ordered systems and extend the quasiparticle paradigm of magnons in spin-ordered systems to the charge sector, with electric charge replacing spin angular momentum as the transported quantity.
Strongly Correlated Electrons (cond-mat.str-el)
Tuning the Coercive Field in Ferroelectric Hf0.5Zr0.5O2-Al2O3 Heterostructures via Interfacial Charge Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Marshall B. Frye (1), Chanyoung Kim (1), Jeong-Woo Sun (1), John Wellington-Johnson (1), Lance Fernandes (2), Prasanna Venkatesan Ravindran (2), Bogdan Dryzhakov (3), TaeYoung Song (2), Mengkun Tian (4), Asif I. Khan (1 and 2), Lauren M. Garten (1) ((1) School of Materials Science and Engineering, Georgia Institute of Technology, (2) School of Electrical and Computer Engineering, Georgia Institute of Technology, (3) Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, (4) The Institute for Matter and Systems, Georgia Institute of Technology)
Interleaving dielectric layers into ferroelectric Hf0.5Zr0.5O2 (HZO) films increases the memory window (MW) beyond what is accounted for by the dielectric constants. Determining the physical mechanisms behind these MW improvements is critical to reaching the full potential of HZO FeNAND. Here, we show that MW improvements stem from the interfacial charge dynamics enabled by oxygen vacancies at the interlayer interface. X-ray photoelectron spectroscopy(XPS) etching experiments demonstrate increased off-stoichiometry at the interface, with a 2.3x increase in oxygen vacancies. Polarization-dependent XPS and first-order reversal curves(FORC) show that tunneling between interfacial defect states causes a bidirectional internal bias of 0.56MV/cm. The impact of defects is further corroborated through phase-field modeling(PFM), which only recreates the coercive fields, FORC, and internal bias for defect densities and tunneling barrier heights that are consistent with experiment, quantitatively capturing an internal electric field of 0.55 MV/cm. The phase field models are then used to simulate 36 devices with varied charge densities and dielectric thickness to provide a predictive framework for further improvements in the MW of interlayer HZO. These findings redefine the role of defects in ferroelectric HZO from deleterious to engineerable and provide critical insights into how to tune ferroelectric device architectures for improved memory.
Materials Science (cond-mat.mtrl-sci)
35 manuscript pages, 7 figures, 12 supplemental pages, 17 supplemental figures
Strain-Induced Metal-to-Insulator Transition in Antiferromagnetic SrCrO$_3$ Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
S. Jöhr (1), A. Carta (2 and 6), J. Moreno (3), A. Suter (5), Z. Salman (5), A. Panda (2), J. Spring (1), G. De Luca (7), J. Herrero-Martin (8), B. Mundet (9), C. Piamonteze (4), M. Gabay (10), C. Ederer (2), M. Gibert (3) ((1) University of Zurich, Zurich, Switzerland, (2) Materials Theory, ETH Zurich, Switzerland, (3) Technical University of Vienna, Vienna, Austria, (4) PSI Center for Photon Science, 5232 Villigen, Switzerland, (5) PSI Center for Neutron and Muon Sciences, 5232 Villigen PSI, Switzerland, (6) Paul Scherrer Institut, 5232 Villigen, Switzerland, (7) Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), 08193 Cerdanyola del Valles, Spain, (8) ALBA Synchrotron Light Source, 08193 Cerdanyola del Vallès, Spain, (9) Institut de Nanosciència i Nanotecnologia (ICN2), 08193 Cerdanyola del Valles, Spain, (10) University Paris Saclay, Paris, France)
Antiferromagnetic (AF) metals are rare, yet they combine properties attractive for spintronic devices like robustness against stray fields and electrical readout. Among AF metal oxide candidates, SrCrO$ _3$ remains largely unexplored due to its notoriously difficult synthesis. In this paper, we demonstrate the growth of high-quality SrCrO$ _3$ thin films by magnetron sputtering on substrates that impose a wide range of tensile and compressive strains. Muon spin relaxation experiments, supported by x-ray magnetic dichroism, unveil the emergence of an AF phase with dilute magnetic disorder at low temperatures, while resistivity measurements confirm the simultaneous metallic ground state of SrCrO$ _3$ under low strain. As both compressive and tensile strain increase, a metal-to-insulator transition is induced in the films, while the onset of the magnetic transition temperature remains unchanged. Moreover, an intriguing resistivity upturn, accompanied by a change in the dominant charge-carrier type, occurs at a temperature that correlates with strain. These observations suggest a complex strain-dependent band structure, with strain-induced Jahn-Teller distortions or tilting of the CrO$ _6$ octahedra that emerge depending on the sign of the strain, as inferred from density functional theory calculations.
Materials Science (cond-mat.mtrl-sci)
10 Pages, 4 figures, Supplement Information with additional 5 pages, 7 figures
Unified hydrodynamics for density and spin supersolids
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-18 20:00 EDT
Ashwath N. Madhusudan, Au-Chen Lee, P. B. Blakie, R. N. Bisset
Two-component supersolids can exhibit in-phase or out-of-phase component density modulations, corresponding to density and spin supersolids, respectively. We formulate a general hydrodynamic theory for the collective dynamics of multicomponent supersolids, guided by their broken symmetries and conservation laws. We benchmark it against microscopic calculations for a binary dipolar condensate confined to an infinite tube, finding quantitative agreement for the sound speeds of all three Goldstone branches throughout the density- and spin-supersolid regions. The resulting relations link collective-mode measurements to elastic coefficients and superfluid fractions.
Quantum Gases (cond-mat.quant-gas)
8 pages, 4 figures
Unconstrained compact lattice QED$_{2+1}$ coupled to phonons: Gauss sectors, orthogonal semimetal, and deconfined criticality
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
João C. Inácio, Fakher F. Assaad
Gauge theoretic descriptions of 2D quantum magnets are defined on a restricted physical Hilbert space by imposing Gauss’s law. In this work, we study an unconstrained compact lattice QED$ _{2+1}$ coupled to bond phonons, in which local Gauss operators are conserved, but their eigenvalues are not a priori fixed. Using exact auxiliary-field quantum Monte Carlo simulations at $ N_f = 2$ , we investigate how the physical Gauss sector becomes energetically favourable, and how this process is connected to confinement and symmetry breaking. We identify an orthogonal semimetallic (OSM) phase, in which fermions striped off their gauge charge and form a Dirac liquid. This phase mixes various Gauss sectors, and becomes unstable when Gauss’s law is explicitly enforced. Upon the imposition of Gauss’s law, compactness allows for monopole excitations carrying antiferromagnetic (AFM) and valence-bond-solid (VBS) quantum numbers. Gauge field fluctuations and spinon-phonon coupling tune between the competition of such monopoles and generate a phase diagram with OSM, AFM and VBS orders. The transitions out of the OSM phase coincide with the dynamical generation of Gauss’s law, while the competition between AFM and VBS charged monopoles produces a transition consistent with deconfined quantum criticality. Thus our results establish that upon the projection to the physical Hilbert space, deconfinement in compact lattice QED$ _{2+1}$ is always unstable towards either AFM or VBS order.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat)
Formal Fluctuation-Response Relations for Non-Stationary Systems: The Dynamic Conjugate Variable
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Fluctuation-response relations (FRRs) connect the linear response of a system to an external perturbation with properties of spontaneous fluctuations in the unperturbed system. We provide a simple derivation of FRRs for non-stationary dynamics following an almost standard way based on introducing a variable conjugated to perturbation (a dynamic conjugate). The derivation relies solely on the Markovianity of the underlying dynamics, with the only additional assumption that the transition PDF of the process is differentiable with respect to the strength of a constant, time- independent perturbation. The structure of this conjugate variable is however unusual: it is a two-time one, and reduces to a usual single-time conjugate in stationary situations. We show how several known results follow from this approach.
Statistical Mechanics (cond-mat.stat-mech)
17 pages
Multiconfigurational Analysis of Local Electronic Structure of $\mathrm{RuO_2}$ Using Relativistic Embedded Clusters
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Zhosan I. A., Lomachuk Yu. V., Maltsev D. A., Moiseev I. A., Andreev O. Yu
We present a multiconfigurational, relativistic embedded-cluster study of the local electronic structure of ruthenium dioxide ($ \mathrm{RuO_2}$ ), a candidate altermagnetic material. Starting from free $ \mathrm{Ru}$ ions, we progressively build up the local environment through a $ \mathrm{Ru+Q_6}$ electrostatic model, a bare $ \mathrm{[RuO_6]^{8-}}$ ligand model, and finally a high-accuracy $ \mathrm{RuO_6}$ @CTEP embedded cluster that reproduces the crystalline surroundings. All systems are treated at the SA-CASSCF and NEVPT2+SOC levels of theory to capture strong electron correlation and spin-orbit coupling on an equal footing. While the formal local site symmetry of the $ \mathrm{Ru}$ sites in $ \mathrm{RuO_2}$ is orthorhombic ($ D_{2h}$ ), we find that the calculated $ 4d$ -orbital energy spectrum and its splitting pattern behave much closer to the higher tetragonal ($ D_{4h}$ ) symmetry, preserving a strong quasi-degeneracy among the relevant $ 4d$ orbitals. Since the local $ xy$ quadrupolar order responsible for altermagnetic spin splitting in independent-particle models relies on this symmetry reduction, its suppression by orbital quasi-degeneracy offers a natural explanation for why altermagnetism is not observed in bulk $ \mathrm{RuO_2}$ experiments, in contrast to the robust altermagnetic signatures reported in strained thin films.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Lyapunov-controlled thermalization: an exact real-time example
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
A verified Kubo-Martin-Schwinger (KMS) relation, after a drive has ceased, is not sufficient evidence to prove equilibrium. We demonstrate this in a large-$ N$ large-$ q$ Sachdev-Ye-Kitaev (SYK) quench protocol. Although all post-quench fermion correlators are exactly thermal, a second quench back to the initial Hamiltonian reveals hidden memory of the initial state. It is encoded in correlators connecting to times before the first quench. This memory is an extensive nonequilibrium (NEQ) witness with its decay rate being the Lyapunov exponent $ \lambda_L$ . Thus $ \lambda_L$ sets the rate at which the state becomes effectively indistinguishable from a Gibbs state. Despite being a unitary interacting many-body system, the complete NEQ real-time evolution is obtained exactly in the large-$ N$ , large-$ q$ limit, making the setup ideal for analytically studying thermalization.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
11 pages, 4 figures
Magnon-Phonon Dynamics in Multidimensional Antiferromagnetic Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Yogendra Limbu, Michael E. Flatté, Durga Paudyal
Antiferromagnetic oxides offer a compelling paradigm for magnonics. Combining ab initio and spin Hamiltonian modeling, we map Cr2O3 from bulk to monolayer limits, verifying stability via phonon spectra. Contrary to previously predicted half-metallic ferromagnetic monolayer phases, we conclusively demonstrate that monolayer and bilayer configurations preserve an antiferromagnetic semiconductor ground state despite systematic gap narrowing. Intersecting magnon and phonon branches drive strong hybridization, establishing low-dimensional Cr2O3 as an ideal platform for quantum spintronics.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Spin-Lattice Dynamics and Interactions in Magnonic Spinels
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Hari Paudyal, Yuri Suzuki, Michael E. Flatté, Durga Paudyal
Minimizing magnetic damping while understanding spin-lattice interactions remains a key challenge for magnonics. We show site-specific Al/Li ordering in spinel ferrites drives a ferrimagnetic insulating state, quenching the Fermi-level density of states. \textit{Ab initio} calculations reveal collective acoustic modes alongside sub-lattice-selective optical modes on tetrahedral and octahedral networks, providing a microscopic understanding of substitution-driven spin dynamics. Crucially, the low-frequency magnon and acoustic phonon modes intersect, driving strong hybridization for low-loss technologies.
Materials Science (cond-mat.mtrl-sci)
8 pages and 3 figures
First-principles theory of phonon renormalization from nonlinear electron-phonon interactions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Florian Kluibenschedl, Matthew Houtput, Jacques Tempere, Cesare Franchini, Mikhail Lemeshko, Ragheed Alhyder
Electron-phonon interactions renormalize phonon frequencies and lifetimes and are central to the dynamical properties of solids. While these effects are usually described within linear electron-phonon coupling, the role of nonlinear electron-phonon interactions for phonon properties remains largely unexplored. In this work, we study phonon renormalization arising from the long-range linear one-electron-one-phonon and the nonlinear one-electron-two-phonon interactions within a diagrammatic framework. We derive the corresponding self-energy diagrams, which depend on the chemical potential and temperature, and evaluate them from first principles for the two polar semiconductors LiF and KTaO$ _3$ . In both materials, the two interaction channels renormalize the phonon spectrum in qualitatively distinct ways. The linear contribution is sharply localized near the Brillouin-zone center, whereas the nonlinear process couples an incoming phonon to other branches throughout the spectrum. As a result, it renormalizes phonons across the entire Brillouin-zone, with a pronounced temperature dependence governed by the thermal occupation of those branches. This behavior provides a clean experimental signature of the one-electron-two-phonon coupling. While the nonlinear phonon renormalization is small in LiF, it is somewhat larger in KTaO$ _3$ , which we attribute to its greater number of thermally populated phonon branches at room temperature. Our results establish a general framework to assess nonlinear electron-phonon effects on the phonon properties in materials with stronger lattice fluctuations, including soft semiconductors such as lead-halide perovskites.
Materials Science (cond-mat.mtrl-sci)
33 pages, 13 figures
A Gaussian process coarse-grained potential for Na-montmorillonite
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-18 20:00 EDT
Yalda Pedram, Yaoting Zhang, Laurent Brochard, Chang Seok Kim, Laurent Karim Béland
Hydraulic transport in compacted bentonite is diffusion-controlled and governed by the hydration and microstructure of sodium montmorillonite (Na-MMT). Experiments cannot resolve how platelet interactions govern pore structure, transport and stiffness, while existing coarse-grained models smooth hydration oscillations or require manual corrections. We develop a tabulated potential combining Morse interactions between platelet centre and edge sites with a Gaussian process regression correction trained on all-atom potentials of mean force. It captures the hydration-induced complexity of the potential-of-mean-force profiles, including the three-water (3-W) hydration minimum and transfers across geometries, layer-charge variants and unseen configurations. Applied to monodisperse and polydisperse Na-MMT assemblies at dry densities of 0.8-1.3 g cm^-3, the model captures the 3-W to 1-W transition, loss of non-interlayer porosity and evolution of pore structure, random-walk tortuosity, diffusion and stiffness. Predicted diffusion agrees with compacted Na-bentonite measurements.
Materials Science (cond-mat.mtrl-sci)
58 pages, 8 figures
Martingale theory for heat and phase-space contraction in heterogeneous diffusions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Jing Qin, Nariya Uchida, Édgar Roldán
We investigate martingale properties of heat dissipated by generic non-equilibrium overdamped Langevin dynamics with multiple dimensions and transport coefficients that may depend explicitly on time and/or space. We find quantitative criteria that establish that heat dissipation may exhibit transient martingale (time-conserved), submartingale (time increasing), and supermartingale (time decreasing) properties in Langevin dynamics with drift coefficients with spatial non-linear dependencies. Furthermore, we reveal a tight link between the heat statistics at stopping (e.g. first-passage) times with that of a functional quantifying the phase-space contraction in the system dynamics. The theoretical results are used to predict the statistical properties of the heat dissipated by a spherical microscopic particle subject to gravity and double-layer forces and hydrodynamically interacting with a rigid wall, whose validity is confirmed by numerical simulations. These results extend the scope of stochastic energetics by revealing a non-trivial relation between heat fluctuations’ statistical properties and the non-linear features of non-equilibrium processes.
Statistical Mechanics (cond-mat.stat-mech)
Active Hydrodynamics Couples Polymer Organization, Shape Fluctuations, and Motility in Deformable Droplets
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
We study semiflexible active polymers confined within a soft, deformable droplet suspended in a fluid using dissipative particle dynamics (DPD) simulations. Extensile and contractile force dipoles along the polymer backbone generate distinct hydrodynamic flow fields that mediate effective interactions between polymer segments. Extensile activity promotes parallel alignment and lateral attraction, whereas contractile activity favors predominantly perpendicular organization, leading to qualitatively different collective behavior. The activity-generated flows couple strongly to the deformable interface, selectively enhancing low-order spherical-harmonic modes associated with long-wavelength droplet deformations. Activity also drives the interfacial relaxation away from passive capillary behavior, with extensile and contractile droplets exhibiting distinct mode-dependent dynamics. These differences in internal organization and interfacial fluctuations strongly influence droplet motility. Extensile activity produces increasingly persistent droplet motion with increasing polymer number, whereas contractile activity can sustain long-lived near-ballistic motion whose duration depends sensitively on polymer number and activity strength. Our results demonstrate how active hydrodynamics governs the interplay between internal structure, interfacial fluctuations, and emergent motility in confined active matter systems.
Soft Condensed Matter (cond-mat.soft)
Scaling and Condensation of Dry Active Matter Around Circular Obstacles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Felipe P. S. Júnior, F. Q. Potiguar, Jorge L. C. Domingos, W. P. Ferreira
Active Brownian particles confined to rigid substrates are known to accumulate near rigid boundaries and, under suitable conditions, undergo motility-induced phase separation (MIPS). A particularly intriguing manifestation of this behavior is the formation of self-sustained vortices around circular obstacles, which act as localized nucleation sites for particle aggregation. While several dynamical properties of such vortices have been previously characterized, their behavior in the thermodynamic limit remains largely unexplored. Here, we investigate how the mass and spatial extent of a dry active-matter vortex scale with system size. Using numerical simulations of repulsive active Brownian Particles interacting with a fixed circular obstacle, we measure the vortex mass, mean radius, and maximum radius as functions of the global area fraction, obstacle size, and system size. We find two distinct scaling regimes. At low densities, the vortex remains localized and its characteristic properties saturate as the system size increases. Above a critical density, however, the vortex mass grows extensively with the total number of particles, while its spatial dimensions scale linearly with the system size, indicating the emergence of an obstacle-stabilized condensed state.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
26 pages and 8 figures
Engineering Weak Universality with Quantum Dots
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Warre Missiaen, Michael Wimmer, Natalia Chepiga
Quantum critical theories with continuously varying critical exponents remain challenging to access experimentally. Here, we propose quantum-dot architectures for realizing the quantum Ashkin-Teller and XYZ/eight-vertex models using resonator-mediated and direct Coulomb interactions, respectively. We focus on the Ashkin-Teller and eight-vertex critical lines, which are connected by a non-local duality relating local order parameters to topological string operators. The resulting platforms provide microscopic control over the parameters explicitly controlling critical exponents, with the Coulomb-based implementation enabling stronger interaction regimes. We demonstrate that continuously varying critical behavior can already be resolved in short chains. For experimentally realistic parameters, the accessible interaction range is expected to produce changes in the critical exponents of order $ 10%$ for the Ashkin-Teller model and substantially larger changes for the eight-vertex model. In both cases, the predicted variations lie well above the estimated measurement uncertainties.
Strongly Correlated Electrons (cond-mat.str-el)
Spacetime Dynamics of Altermagnetic Magnons
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Ali Emami Kopaei, Karthik Subramaniam Eswaran, Krzysztof Wohlfeld
Distinguishing altermagnetism from conventional ferromagnetism and antiferromagnetism typically relies on momentum-space probes. Here, we show that the real-space spreading of a localized spin excitation provides a distinctive dynamical fingerprint of altermagnetic order. Using linear spin-wave theory on a two-dimensional checkerboard lattice with nearest-neighbor and next-nearest-neighbor couplings J_1 and J_2, we demonstrate that finite J_2 produces direction-dependent magnon group velocities and splits the two magnon branches. The resulting propagation remains closer to that of an antiferromagnet than a ferromagnet, retaining an approximately circular outer wavefront, while the direction-dependent magnon velocities produce a pronounced cross-like spatial structure inside this front. We further show that changing the sign of J_2 to enter the unfrustrated regime (J_2<0) increases the characteristic propagation velocities and interchanges the diagonal directions of enhanced propagation, corresponding to a pi/2 rotation of the anisotropic spatial pattern. These results establish spacetime dynamics as a complementary probe of altermagnetic magnons, providing a route to identifying unconventional magnetic order through real-space propagation patterns in solid-state and synthetic quantum systems.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Quantum Gases (cond-mat.quant-gas)
10 pages, 7 figures
Coherent and ultra-low-power EDSR with a flopping-mode spin qubit in germanium
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-18 20:00 EDT
Alexei Orekhov, Wonjin Jang, Pan Zhang, Konstantinos Tsoukalas, Fabian Oppliger, Franco De Palma, Elena Acinapura, Younghun Ryu, Inga Seidler, Lisa Sommer, Leonardo Massai, Felix J. Schupp, Matthias Mergenthaler, Stefano Bosco, Patrick Harvey-Collard, Pasquale Scarlino
Hole spin qubits in semiconductor quantum dots (QDs) enable high-fidelity all-electric control, but conventional electric dipole spin resonance (EDSR) can require substantial rf drive power at the low magnetic fields that are favorable for qubit coherence and readout. In planar Ge hole spin qubits, this can reach -27 dBm at the device, posing challenges for scalable architectures due to heating and crosstalk. Here, we demonstrate a flopping-mode (FM) qubit in Ge, where a single spin is delocalized in a double QD, combining first-order protection against charge noise with exceptionally efficient electric driving. By mapping out coherence sweet-spots as a function of magnetic field orientation we achieve $ T_2^\ast= 1.4\mu\mathrm{s}$ , $ T_2^{\mathrm{Hahn}}= 11.5 \mu\mathrm{s}$ , $ T^{\phi, \mathrm{CPMG32}}2= 130 \mu\mathrm{s}$ , and $ T_1= 226 \mu \mathrm{s}$ , and a single-qubit gate fidelity of up to 99.76$ %$ for a gate time $ t{X\pi} = 88$ ns. Importantly, these results are obtained at a nearly in-plane magnetic field of 5 mT using only -52 dBm drive power at the device. We further find that qubit relaxation in this regime is consistent with a two-photon Orbach process, providing a route for further optimization. Our results demonstrate that FM-EDSR supports ultra-low-power, high-fidelity single-qubit operations, improvements that could benefit scalable hole-spin-based architectures and hybrid spin-photon interfaces.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Global Minima of the Thomson Problem in a Disk: A Molecular Dynamics Approach with Fixed Border Charges
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-18 20:00 EDT
Georgiy K. Lavrov, Eduard G. Nikonov
We report improved global-minimum configurations for the classical Thomson problem of $ N=60$ , $ 61$ , $ 92$ , and $ 99$ repulsive Coulomb charges confined to a disk. By combining the quenched molecular dynamics (QMD) method with the fixed-border heuristic introduced by Amore and Zarate, we systematically obtain configurations with energies $ E_{\mathrm{QMD}}(60)=2159.3584240930$ , $ E_{\mathrm{QMD}}(61)=2237.19264190$ , $ E_{\mathrm{QMD}}(92)=5358.35353314$ , and $ E_{\mathrm{QMD}}(99)=6254.83029083$ , which improve upon the previously best-known values. For $ N=60$ , the Voronoi diagram of our configuration differs from the one reported earlier. The symmetries for $ N=61$ $ (C_{2})$ and $ N=99$ $ (D_{1})$ are confirmed and are consistent with the known symmetry patterns for these configurations. For $ N=92$ , whereas the previously reported Voronoi diagram has lower symmetry, our solution exhibits a clear $ D_{1}$ (axial) symmetry of defects. The results are highly reproducible across multiple independent runs, providing strong evidence that these configurations are robust global-minimum candidates.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Optimization and Control (math.OC), Classical Physics (physics.class-ph), Computational Physics (physics.comp-ph)
10 pages, 1 figure, 1 table
Competing routes to spontaneous flow in confined active nematics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-18 20:00 EDT
Rahil N. Valani, Vedad Dzanic, Sumesh P. Thampi, Julia M. Yeomans
Active nematics can spontaneously develop flow beyond a critical activity in confined geometries. We show analytically that the onset of flow is governed by two competing instabilities: a long-wavelength mode leading to unidirectional flow and a finite-wavelength instability producing transverse rolls. A reduced description reveals how activity, flow alignment, and nematic elasticity control the competition between these modes. We identify regimes in which the finite-wavelength instability has a lower critical activity than the long-wavelength instability, causing vortices to emerge before unidirectional flow. This establishes wavelength selection as an intrinsic feature of the onset of spontaneous flow in active nematics.
Soft Condensed Matter (cond-mat.soft)
5 pages, 3 figures
Statistics, ‘t Hooft Anomaly, and the Else-Nayak Index: a careful comparison of concepts
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-18 20:00 EDT
Generalized symmetries and topological excitations, as well as symmetry anomalies and the statistics of topological excitations, are widely believed to be related. There are, however, pitfalls in how this relation is established. A lattice truncation of a symmetry transformation to a finite patch gives a symmetry patch operator that creates symmetry defects at its boundary. This geometric picture resembles a hopping operator creating topological excitations at the boundary of its support, but does not provide well-defined statistics, let alone guarantee agreement with the symmetry anomaly. A more natural and robust relation is that the hopping operators of topological excitations are symmetric: they commute with symmetry transformations. Under suitable assumptions, this condition yields a one-to-one correspondence between statistics and anomalies. We further couple boundary matter to a DW gauge field in one higher dimension to explain this relation from the perspective of gauging. A hopping operator is, in essence, a gauge-invariant operator acting on the physical degrees of freedom after gauging. Once the gauge-field background is fixed, global symmetry comes from gauge transformations that preserve that background, while the symmetric condition on hopping is precisely the remaining gauge invariance. This distinction clarifies potential misconceptions in the literature and provides a more reliable framework for comparing symmetries and topological excitations.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
50 pages
Research Square
Enhancing Secure Key Rates via Redundant Information-Reconciliation Leakage Elimination in Practical Quantum Key Distribution Chips
Article | Quantum optics | 2026-09-17 20:00 EDT
Hao Yu, Hao-Kun Mao, Bo Yang, Xiao-Peng Wang, Xin-Jie Zhang, Yu-Cheng Qiao, Bing-Ze Yan, Bingjie Xu, Lip Ket Chin, Hong Cai, Ai Qun Liu, Qiong Li
Information reconciliation (IR) in quantum key distribution (QKD) is usually treated as leaking the total amount of publicly disclosed reconciliation information. In weak-coherent-pulse decoy-state QKD, this can be overly conservative under the Gottesman-Lo-Lütkenhaus-Preskill (GLLP) tagging framework, because disclosures determined by tagged multi-photon bits that are already assumed known to an eavesdropper reveal no additional information and therefore need not be counted again as IR leakage. Here, we experimentally demonstrate a tighter IR-leakage estimation model that excludes this redundant contribution and bounds the additional information the eavesdropper acquires during reconciliation. The model is incorporated into asymptotic and composable finite-key analyses of decoy-state BB84 while leaving the constant privacy-amplification contribution and the underlying GLLP security assumptions unchanged. We experimentally evaluate the model using 2.5 GHz silicon-photonic chips with polarization-encoded decoy-state BB84 protocol under controlled channel loss and over a 55.41 km deployed metropolitan fiber link. The experimental results show a secure key rate increment of up to 78.82%, while the corresponding finite-key analysis indicates ~ 2.35 dB of additional tolerable system loss. These results experimentally demonstrate that tighter reconciliation-leakage accounting can improve the secure key rate performance of practical chip-based QKD systems without modifying the quantum hardware or the public communication required for reconciliation. Consequently, this methodology holds significant potential across diverse real-world quantum-secure communication scenarios, including high-demand metropolitan and intercity networks, satellite-to-ground QKD links, and next-generation quantum internet nodes.
Research Square:rs-10675943 (2026)
Posted on Research Square and Under Review at Light: Science & Applications
Physical sciences/Optics and photonics/Optical physics/Quantum optics, Physical sciences/Optics and photonics/Applied optics/Integrated optics