CMP Journal 2026-06-15
Statistics
Nature: 1
Nature Physics: 1
arXiv: 64
Nature
Nanocrystal-tailored recombination for all-perovskite tandem solar modules
Original Paper | Nanoparticles | 2026-06-14 20:00 EDT
Ke Xiao, Hongfei Sun, Xinke Kong, Han Gao, Jing Lou, Xingze Chen, Zimo Hu, Dongdong Xu, Renxing Lin, Runnan Liu, Siyu Xia, Jin Xie, Ye Liu, Xin Luo, Fengjia Fan, Changqi Ma, Chao Chang, Yuanyuan Wang, Hairen Tan
The commercialization of all-perovskite tandem solar modules is hindered by the reliance on the conventional gold-based tunnel recombination junction (TRJ)1,2. Specifically, this TRJ introduces substantial near-infrared parasitic absorption3 and suffers from interfacial instability4, limiting both photocurrent generation and operational durability. Here, we develop a solution-processed interconnecting layer based on surface-engineered indium oxide (In2O3) nanocrystals featuring high optical transparency, wherein controlled nanocrystal morphology and tailored ligand chemistry enable smooth interfacial contact and favorable energy level alignment. Critically, we introduce a phosphonic acid additive into the lead-tin (Pb-Sn) perovskite precursor, which synergistically improves the electronic contact with the In2O3 recombination layer, thereby enhancing hole extraction. In addition, the additive regulates perovskite crystallization to mitigate residual strain during film formation, ensuring high-quality large-area deposits. This coordinated interfacial and crystallization engineering strategy simultaneously enhances carrier recombination efficiency at the interconnection layer, improves carrier extraction, and promotes large-area film uniformity in all-perovskite tandems. As a result, a 65-cm2 all-perovskite tandem solar module achieves a certified power conversion efficiency of 26.2%5, with an open-circuit voltage of 2.182 V, a fill factor of 77.4%, and a short-circuit current density of 15.6 mA cm-2 in terms of averaged subcell performance, measured by Japan Electrical Safety and Environment Technology Laboratories (JET). This marks a significant advance toward scalable perovskite tandem photovoltaics.
Nanoparticles, Solar cells
Nature Physics
Quantum Fisher information in a strange metal
Original Paper | Phase transitions and critical phenomena | 2026-06-14 20:00 EDT
Federico Mazza, Sounak Biswas, Xinlin Yan, Andrey Prokofiev, Paul Steffens, Qimiao Si, Fakher F. Assaad, Silke Paschen
A strange metal is an exotic state of correlated quantum matter, and intensive efforts are ongoing to understand its nature. Here we show that the quantum Fisher information–a concept from quantum metrology–may provide helpful insights. We use inelastic neutron scattering and quantum Monte Carlo simulations to study quantum critical fluctuations of the Kondo destruction type, which are considered to underlie strange metal behaviour in heavy-fermion compounds. We find that the associated quantum Fisher information increases strongly and without a characteristic scale as the strange metal forms with decreasing temperature. This provides evidence for a quantum state with high multipartite entanglement and offers a positive descriptor of strange metallicity that points towards its microscopic basis. Our work opens a direction for future studies across a range of strange metal platforms.
Phase transitions and critical phenomena, Theoretical physics
arXiv
Controlling Defects and Probing Dynamics in Active Nematics with Deep Reinforcement Learning
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Russ Islam, Kyogo Kawaguchi, Yuto Ashida
Topological defects govern much of the flow behavior and orientational order in active nematics, making their control relevant for active matter physics, smart materials, and microfluidics. Applied activity patterns can induce self-propulsion of active nematic defects, but general-purpose methods for exploiting this effect to control defects remain largely unexplored. Here we use deep reinforcement learning (RL) to perform minimum-time position control of +1/2 defects in hybrid lattice Boltzmann simulations of active nematodynamics. Spatiotemporally patterned activity, implemented as a control field in the active stress, steers defects through microchannel geometries and reveals finite-time reachable regions of defect position space. Reachability is shaped by director anisotropy, homeotropic wall anchoring, and the allowed activity patterns: local patterns steer defects in free domains but fail in junctions, whereas global patterns open otherwise inaccessible channels. In constrained geometries, the original defect may be unable to reach some goals intact, but controlled pair creation enlarges the effective reachable set by transferring control to a newly created +1/2 defect. The trained RL controllers outperform static and rule-based baselines, and controllers trained only on simple junctions can be combined without fine-tuning into a meta-controller that successfully steers defects through a larger test maze. Free energy visualizations show that guided defects write persistent, history-dependent distortions into the director field that can later be partially erased by -1/2 defects. Thus, RL-based control uncovers how confinement, anchoring, actuation geometry, and defect creation determine reachable motion in active nematics, providing a framework for other control tasks in soft and active matter.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
24 pages, 14 figures
Electrostatic Charge Model for Dual-Layer Oxide Thin-Film Transistors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Måns J. Mattsson, John F. Wager, Matt W. Graham
A simple electrostatic two-equation model for dual-layer thin-film transistor (TFT) operation is developed. The model distributes electrostatic charge between the top and bottom semiconductor layers, and the resulting transfer and mobility curves accurately simulate experimental dual-layer a-IGZO/a-IZO TFT operation. The model further provides an analytic expression that maps charge confinement in the high-mobility a-IZO bottom semiconductor layer with the a-IGZO top-layer thickness and the conduction-band offset. By considering both a-IGZO/a-IZO layer charge partition and competing thickness-dependent oxygen vacancy trap density effects, the model suggests an optimal a-IGZO layer thickness of 9 to 12 nm. Importantly, this general electrostatic model extends to most dual-layer TFT systems and calculates how the top semiconductor layer TFT turn-on voltage changes sharply with the conduction band offset and layer thickness.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
7 pages, 5 figures
Digital programming of spin correlations in a fermionic lattice quantum simulator
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-15 20:00 EDT
Yann Kiefer, Lars Fischer, Zijie Zhu, Konrad Viebahn, Tilman Esslinger
Analog quantum simulation provides a highly controlled platform to study diverse quantum many-body phenomena. However, current methods for state initialisation are limited to thermal ensembles or uncorrelated product states. Here we present a hybrid approach that complements analog preparation with a digital quantum-gate protocol. This approach enables the engineering of target states with specific, long-range spin-correlations from the same initial resource state. By applying collisional gates to adiabatically prepared and filtered four-fermion singlet chains, we program diverse spin-correlation patterns, including that of a Heisenberg chain. We measure the spin correlations using a sequence of quantum gates followed by singlet-pair measurements. Our method paves the way to the targeted preparation of strongly correlated states of matter.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Enhancement of spin current in Fe${85}$Co${15}$/Ni${80}$Fe${20}$ bilayers via interlayer ferromagnetic coupling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
A. A. Pérez Martínez, D. Velázquez Rodríguez, D. Goijman, T. Torres, M. H. Aguirre, J. Gómez, A. Butera, E. De Biasi, J. Milano
We present a detailed study on how the strength of the interlayer magnetic coupling on Fe$ _{85}$ Co$ _{15}$ /Ni$ _{80}$ Fe$ _{20}$ bilayers modifies the spin wave behavior of this system. A series of Fe$ _{85}$ Co$ _{15}$ /Ni$ _{80}$ Fe$ _{20}$ bilayers deposited on MgO[100] substrates were grown by magnetron sputtering. Magnetic characterization of the samples was performed using a vibrating sample magnetometer and magneto-optical Kerr effect. The in-plane hysteresis loops reveal a cubic magnetic anisotropy of magnetocrystalline origin, with easy and hard axis along the [100] and [110] Fe-Co crystallographic directions, respectively. Ferromagnetic resonance measurements were performed to analyze the in-plane angular dependence of the resonance field, and also the resonance field at several frequencies was determined along the hard axis. By using a bilayer model in the frame of the Landau-Lifshitz-Gilbert magnetization equation of motion, the magnetization precession components were calculated, as well as the dependence of precession area on the Fe-Co layer thickness and the ferromagnetic interlayer coupling. We observe a maximum in the area of the ellipsoid generated by the magnetization precession of the permalloy layer at a certain exchange constant, showing that this effect could be used to maximize the injected spin currents, which could be tuned by changing the interlayer exchange constant in bilayer systems, the saturation magnetization of the materials, or the excitation frequency.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 14 figures
Observation of intertwined charge density wave order and superconductivity in Janus monolayer
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-15 20:00 EDT
Subhajit Pramanick, Shubham Patel, Sudip Chakraborty, A. Taraphder
Low-dimensional transition-metal dichalcogenides (TMDCs) provide an ideal platform for studying the emergence of charge density wave (CDW) and superconductivity. The discovery of emergent CDW order in 1T $ \mathrm{ZrTe_2}$ monolayer raises an important question: does this instability persist when one $ \mathrm{Te}$ chalcogen layer is substituted by $ \mathrm{Se}$ ? In the present work, we investigate the CDW (2$ \times$ 2$ \times$ 1) and superconducting instability in 1T $ \mathrm{ZrSeTe}$ Janus monolayer using first-principles calculations. The phonon spectrum exhibits a pronounced anomaly at the $ \mathrm{M}$ point of the irreducible Brillouin zone, arising from enhanced electron-phonon interaction together with electronic instabilities originating from both interband and intraband scattering. The resulting lattice distortion reconstructs the electronic structure, opening a small indirect band gap, driving the system from a semi-metallic to a semiconducting state. The energy gain associated with the distortion is significantly smaller than that of $ \mathrm{ZrTe_2}$ monolayer, indicating that the replacement of one $ \mathrm{Te}$ chalcogen layer with $ \mathrm{Se}$ weakens the CDW instability. We have further investigated the effects of electronic correlation and biaxial strain, both acts as effective tuning parameters for the instabilities concerened. In the high temperature undistorted phase, $ \mathrm{ZrSeTe}$ exhibits phonon mediated two-gap superconductivity. It originates primarily from the robust coupling between the soft phonon mode at $ \mathrm{M}$ point and the electronic bands predominantly derived from $ \mathrm{Zr}$ $ \mathit{d}$ and $ \mathrm{Te}$ $ \mathit{p}$ orbitals crossing the Fermi level. Spin-orbit coupling (SOC) further modifies the electronic states and reduces the superconducting transition temperature.
Superconductivity (cond-mat.supr-con)
18 pages, 16 figures
A Collective-Spin Derivation of the Uniform Magnon Hamiltonian in Cavity Magnonics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
Tomas Aguiar, Marcos Cesar de Oliveira
We present a direct collective-spin derivation of the effective uniform-mode Hamiltonian used in cavity magnonics. Starting from a nearest-neighbor Heisenberg ferromagnet coupled to long-wavelength magnetic fields, we show that the relevant dynamics can be restricted to the fully symmetric spin sector, where the exchange interaction contributes only a constant energy shift and the ferromagnet behaves as a macrospin of length $ Ns$ . Applying the Holstein–Primakoff transformation directly to this total spin yields the usual uniform magnon mode and its leading nonlinear corrections without first introducing site-resolved bosonic operators. This collective formulation makes explicit the interpretation of the ferromagnet as a synthetic large-spin atom and provides a compact route to the effective Hamiltonians used in driven and Floquet cavity magnonics. As a physical consequence, the leading nonlinear correction produces an occupation-dependent reduction of the effective magnon–photon coupling, providing a simple signature of finite-spin saturation under strong uniform-mode driving.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Combining Frozen Trajectory Excitation and TACAW for in silico Time-Resolved Vibrational Electron Energy Loss/Gain Spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Wojciech Marciniak (1 and 2), Joanna Marciniak (1 and 3), José Ángel Castellanos-Reyes (1), Ján Rusz (1) ((1) Department of Physics and Astronomy, Uppsala University, Sweden (2) Institute of Physics, Poznan University of Technology, Poland (3) Institute of Molecular Physics, Polish Academy of Sciences, Poland)
Seeing that ultrafast (picosecond timescale) vibrational electron energy loss spectroscopy (EELS) should soon be experimentally realizable, we present in silico approach capable of providing insight from the computational physics perspective. We present a framework that combines frozen trajectory excitation (FTE) with time auto-correlation of auxiliary wavefunctions (TACAW) to study the time-dependent spectral response of non-equilibrium lattice dynamics in a way comparable directly to experiment - (scanning) transmission electron microscope EELS, (S)TEM-EELS. In this approach, a selected phonon excitation is first introduced into an equilibrium molecular dynamics trajectory using FTE, after which the atomic positions during subsequent relaxations are treated with short-time TACAW analysis performed at different pump-probe delays. This yields momentum- and energy-resolved electron-scattering signals bearing a phonon imprint during the relaxation process, going beyond time-dependent diffuse-scattering intensities alone. We demonstrate the approach for fcc-Ni and 3C-SiC and discuss the observed phonon mode coupling and spectral redistribution during phonon relaxation.
Materials Science (cond-mat.mtrl-sci)
19 pages, 13 figures
Machine-learned dynamics of surface polarons at reduced oxide surfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Reducible oxides exhibit a rich interplay of electronic, structural, and chemical properties that underpins applications in catalysis, photovoltaics, batteries, and energy storage. This interplay is strongly shaped by excess electrons, often introduced by oxygen vacancies, that localize as small polarons and influence charge transport and surface chemistry. At surfaces, these polarons play a central role in charge localization, mobility, and reactivity, yet their finite-temperature dynamics remain difficult to access from first principles. Ab initio molecular dynamics is typically limited to picosecond time scales, precluding statistically meaningful sampling of polaron hopping dynamics. To overcome this limitation, we extend machine-learning-assisted polaron dynamics [V. Birschitzky et al., Phys. Rev. Lett. 134, 216301 (2025)] to redox-active oxide surfaces, using oxygen-deficient rutile TiO2(110) as a paradigmatic case. By accessing several nanoseconds of dynamics over a range of temperatures, we show that small-polaron mobility at the reduced rutile TiO2(110) surface is suppressed by several orders of magnitude relative to the corresponding bulk material, providing a microscopic interpretation of the lower electron mobilities observed in porous rutile TiO2 compared with single-crystal samples. This suppressed mobility arises from the loss of favorable hopping pathways: surface polaron motion is largely confined to planar inter-row trajectories within the second topmost layers, with only rare interlayer hopping events. Oxygen vacancies further reshape the polaron free-energy landscape by acting as attractive centers for excess electrons, biasing the polaron distribution toward nearby Ti sites and promoting occasional charge transfer to the outermost surface layer. These results establish a transferable machine-learning strategy for investigating polaron dynamics in reducible oxides.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Closed-loop discovery of out-of-distribution processing protocols by evolutionary search and uncertainty-aware learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Yu Liu, Stanislav Udovenko, Ching-Che Lin, Jaegyu Kim, Lane W. Martin, Susan Trolier-McKinstry, Sergei V. Kalinin
Many materials and chemical systems exhibit history-dependent responses, where functional outcomes are governed not only by final-state variables but by the time-dependent sequence of fields, temperatures, or chemical potentials applied during operation. Discovering new processing protocols is therefore a high-dimensional search problem in which the control variable is an entire waveform or sample history, and conventional strategies either remain confined to conservative interpolative families or become prohibitively measurement intensive. Here, a closed-loop workflow is introduced that couples evolutionary search over a compact waveform representation with uncertainty-aware deep kernel learning to generate, rank, and experimentally validate candidate protocols. Applied to ferroelectric thin films, with the scanning-probe tip-bias waveform as the protocol and the nonlinear electromechanical response as the reward, the workflow discovers waveform families that enhance nonlinearity by de-aging the film. Spatially resolved before/after measurements show that the best-performing waveforms selectively activate pre-existing, weakly pinned domain-wall segments, whereas the worst drive long-range irreversible switching. This framework reframes protocol tuning as out-of-distribution discovery, generalizable to synthesis and annealing trajectories, battery formation protocols, and other high-dimensional control problems.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
DFTB coupled with NEGF study of the structural, electronic and transport properties of goldene 2D material
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Taoufik Sakhraoui, František Karlický
We report the structural, electronic, and transport properties of the goldene 2D material using the density functional tight-binding (DFTB) method. Electronic transport calculations were conducted in conjunction with the non-equilibrium Green’s functions (NEGF) technique. Our study reveals that the Au 2D material is dynamically and thermally stable, and it possesses good elastic properties. On the other hand, goldene has a linear relationship between current and voltage at low potentials, indicating its metallic character. The calculated current-potential curve correlates well with transmission functions and the electronic density of states around the Fermi level. We also investigated the electronic structure and magnetic properties of silicon (Si)-doped Au 2D material. Our results show that the Si atom can induce a local magnetic state in the goldene monolayer. The resulting magnetic moment is 0.63 $ \mu_B$ .
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dynamical multiferroicity in framework materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Dynamical multiferroicity, which describes the magnetic fields generated by circularly polarized phonons in materials, is an established mechanism for optical control of magnetism. Here we perform ab initio calculations of dynamical multiferroicity in inorganic and organic framework materials, with the goal of identifying materials which enable the generation of large magnetic fields by light. We find the metal–organic framework material Zn(NH$ _4$ )(formate)$ _3$ to have modes with magnetic moments almost twice that of SrTiO$ _3$ ; these modes involve circular motions of NH$ _4^+$ hydrogen ions with high gyromagnetic ratios. The complex structure and flexibility of framework materials can allow such angular momentum localization, and also increase the maximum light-induced magnetization permitted by the Lindemann melting criterion.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 19 figures
Towards Atom-by-Atom Fabrication: Mechanosynthetic donation and abstraction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Brandon Blue, Mathieu Morin, Alex Inayeh, Rosemary Cranston, Cameron J. Mackie, Marc Savoie, Adam Bottomley, Christian J. Imperiale, Zehra Ahmed, Rafik Addou, Aly Asani, Eduardo Barrera-Ramirez, Jeremy Barton, Doreen Cheng, Megan Cowie, Chris Deimert, Tyler Enright, James Zhangming Fan, Robert A. Freitas Jr, Alan T.K. Godfrey, Ryan Groome, Si Yue Guo, Kareem A. Clarcia, Aru Hill, Taleana Huff, Mark Jobes, Robert J. Kirby, Sam Lilak, Hadiya Ma, Adam C. Maahs, Oliver MacLean, Steven M. Maley, Michael Marshall, Terry McCallum, Ralph Merkle, Matthew Moses, Jonathan Myall, Ryan Plumadore, Adam Powell, Henry Rodriguez, Sam Rohe, Luis Sandoval, Khalil Sayed-Akhmad, Benjamin Scheffel, Kashif Tanveer, Bheeshmon Thanabalasingam, Denis A.B. Therien, Janice L. Wong, Reid Wotton, Cristina Yu, Damian G. Allis, Michael Drew, Matthew R. Kennedy, Tait Takatani, Marco Taucer, Dušan Vobornik, Ryan Yamachika, Mathieu Durand
Enabled by inverted-mode scanning tunneling microscopy (IM-STM) and the use of functionalized molecular tools, we demonstrate positionally-controlled mechanosynthetic addition (donation) of carbon and subtraction (abstraction) of silicon atoms on a model build site: atomically clean and crystalline Si(100). The resulting structures represent the first demonstrations of an emerging ability to manipulate radical chemistry with positional control of specific atoms and moieties in 3D. Furthermore, by comparing the behavior of molecular tools designed for atomic donation versus abstraction, we highlight general principles governing molecular tool design for selective and reliable mechanosynthetic functionality.
Materials Science (cond-mat.mtrl-sci)
17 pages, 5 figures. Supplementary Information is available upon request
Multi-modal machine learning analysis of GaSe molecular beam epitaxy growth conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Mingyu Yu, Isaiah A. Moses, Wesley F. Reinhart, Stephanie Law
Autonomous synthesis platforms integrating machine learning with in situ diagnostics have the potential to revolutionize thin-film growth by enabling real-time process optimization and reducing the need for manual tuning. However, their application to molecular beam epitaxy (MBE) remains underdeveloped. Here, we present a machine learning-guided framework for MBE growth of GaSe films, leveraging reflection high-energy electron diffraction (RHEED) as an in situ diagnostic alongside ex situ characterization via X-ray diffraction and atomic force microscopy. Unsupervised learning on RHEED patterns reveals a well-defined boundary between high- and low-quality samples, capturing physically meaningful features. Mutual information analysis shows a strong correlation between RHEED embeddings and rocking curve full-width at half-maximum (fwhm), while the correlation with AFM root-mean-square (RMS) roughness is weak. Among key growth conditions, growth rate most strongly influences fwhm, whereas the Se/Ga flux ratio primarily affects RMS roughness and the RHEED embeddings. Supervised learning models trained to predict fwhm and RMS roughness demonstrate moderate accuracy, with significant improvement achieved by incorporating RHEED embeddings. Furthermore, anomaly detection via residual analysis in supervised learning aligns well with unsupervised classification from RHEED, reinforcing the reliability of the predictive models. This study establishes a data-driven framework for machine learning-assisted MBE, paving the way for real-time process control and accelerated optimization of thin-film synthesis.
Materials Science (cond-mat.mtrl-sci)
Molecular Beam Epitaxy of Mn2In2Se5 van der Waals Layers Using Mn Intercalation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Qihua Zhang, Ke Wang, Wesley Auker, Maria Hilse, Stephanie Law
The weak van der Waals (vdW) force in layered chalcogenide materials has enabled the growth of ternary chalcogenide layers using unconventional approaches. Here, we report the molecular beam epitaxy (MBE) growth of Mn2In2Se5, a spin glass material with high level of magnetic frustration, through the heterointegration of MnSe on In2Se3. Directly depositing {\alpha}-MnSe on the vdW In2Se3 layers results in Mn intercalation, transforming the In2Se3 layer into Mn2In2Se5. Large growth windows, including substrate temperatures from 250-450 °C and Se:Mn flux ratio of 1.1-3.1, have been identified for the intercalation process. With an optimized MnSe deposition time, smooth, single-crystalline, and (0001)-oriented Mn2In2Se5 layers with a root-mean-square (RMS) roughness of 1.5 nm can be synthesized. Further extending the MnSe deposition time results in the growth of uniform rock-salt structured {\alpha}-MnSe (111) layers with a thickness of up to 8 nm and a narrow full-width-at-half-maximum (FWHM) of 0.35° in MnSe (222) XRD rocking curves. This report presents a unique approach for the growths of uniform and single-crystalline Mn2In2Se5 vdW layers using MBE, and potentially opens a pathway for synthesis of ternary vdW chalcogenides by intercalation of new atomic species in binary vdW chalcogenides.
Materials Science (cond-mat.mtrl-sci)
Direct/adaptive-mixture phase-gradient learning for neural-network quantum states with complex phase structure
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-15 20:00 EDT
Yi-Ran Xue, Rui Wang, Baigeng Wang, Chenan Wei
Neural-network quantum states (NQS) are a leading variational tool for quantum many-body physics, yet their optimization is fragile whenever the ground state carries a non-trivial sign or complex phase structure, a situation generic to gauge fields, broken time-reversal symmetry, and fermionic statistics. We trace this fragility to the stochastic estimator of the phase gradient rather than to network expressiveness. The phase sector of the Monte Carlo energy gradient is a noisy score-function estimator; differentiating the local energy instead yields a direct estimator that is unbiased for the same phase force, has far lower variance, and requires only a separated amplitude–phase ansatz. Demonstrated on a 100-site flux ladder, a small network trained this way reaches $ 0.89%$ median error, where tuned standard baselines plateau at $ 1.8%$ and wider or deeper standard-gradient networks degrade from $ 8.4%$ to $ 24.6%$ . The advantage carries over to chiral XXX chains: the direct estimator again converges to a markedly lower error than the standard one, across $ \alpha$ and size; it grows with flux and vanishes in zero-flux controls. An adaptive-mixture of the two estimators is provably never worse in variance than the better endpoint at the optimal mixing coefficient, with seed-resolved diagnostics tracing much of the gain to eliminating failed runs. Estimator design thus emerges as a first-class lever for complex-valued neural quantum states.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el), Machine Learning (cs.LG), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
24 pages, 8 figures
Machine Learning Accelerated SSNEB for Efficient Minimum Energy Pathway Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Yu Zhang, Guanzhi Li, Minkyung Han, Sean Gasiorowski, Daniel Ratner, Chunjing Jia, Yu Lin
Metastable states and their minimum energy pathways (MEPs) are central to understanding transformations and phase stability in complex materials, yet mapping transition pathways between competing states remains computationally demanding and experimentally challenging. Here, we introduce a hybrid solid-state nudged elastic band (SSNEB) framework that integrates two pretrained machine learning models, EquiformerV2 (eqV2) and the equivariant Smooth Energy Network (eSEN), with DFT for energy, force, and stress evaluations. Applied to three solid-state systems, CsPbI$ _3$ , GaN, and TiO$ _2$ , our framework achieves up to a 7-fold speedup while converging to the same pathways predicted by first-principles calculations. Moreover, the hybrid SSNEB framework enables systematic benchmarking of existing ML models, providing both efficiency and reliability for predicting MEPs across various materials.
Materials Science (cond-mat.mtrl-sci)
Oxygen deficiency and valency reconstruction in multiferroic V-doped HfO$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
The interplay of oxygen deficiency and vanadium multiple valency in the candidate multiferroic V-doped $ Pca2_1$ hafnia HfO$ _2$ is studied by first-principles calculations. Low-lying V majority gap states accept electrons from oxygen-vacancy donors, reducing their formation energy, and converting nominal V$ ^{4+}$ centers into V$ ^{3+}$ . The resulting local magnetization and screening changes are reflected in the calculated V core-level shifts, which are consistent with the experimentally observed XPS signatures. The calculated V$ ^{3+}$ /V$ ^{4+}$ population ratio determined by oxygen vacancies only matches experiment in reducing conditions, suggesting that additional electron reservoirs may contribute under ALD growth conditions. A similar scenario also seems to apply to the recently observed multiferroicity in Cr-doped hafnia, where oxygen deficiency is intrinsic to the growth technique.
Materials Science (cond-mat.mtrl-sci)
6 pages, 8 figures
Mean-field theory of myopic self-avoiding fractional Brownian motion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Rashad Bakhshizada, Skirmantas Janušonis, Ralf Metzler, Thomas Vojta
Myopic self-avoiding fractional Brownian motion (FBM) is a stochastic process in which an ensemble of particles is driven by fractional Gaussian noise while being repelled by the gradient of the time-integrated ensemble density [J. House, R. Bakhshizada, S. Janušonis, R. Metzler, and T. Vojta, Phys. Rev. E 112, 034119 (2025)]. Depending on the anomalous diffusion exponent $ \alpha$ characterizing the noise, the process features two dynamical regimes: an interaction-dominated regime ($ \alpha < \alpha_c=4/(d+2)$ ) where the mean-density interaction governs long-time dynamics, and a noise-dominated regime ($ \alpha > \alpha_c$ ) where FBM correlations prevail. In the interaction-dominated regime, the mean-squared displacement grows as $ \langle r^2(t) \rangle \sim t^{4/(d+2)}$ regardless of $ \alpha$ , while for $ \alpha > \alpha_c$ the standard FBM scaling $ \langle r^2(t) \rangle \sim t^{\alpha}$ is recovered. Here, we develop an analytical mean-field theory of myopic self-avoiding FBM, based on a Fokker-Planck approach to the interaction-dominated regime. This allows us to derive closed-form polynomial solutions for the probability density. To compare with computer simulations, we develop an efficient radial binning algorithm that significantly reduces the computational complexity, making large-scale three-dimensional simulations feasible. Extensive simulations in one, two, and three dimensions confirm the analytical predictions. We also discuss the application of the process to the self-organization of serotonergic axons (fibers) in vertebrate brains, where FBM paths with self-avoidance provide a natural framework for understanding spatial heterogeneities of fiber densities.
Statistical Mechanics (cond-mat.stat-mech)
11 pages, 9 figures
XRDiff: Crystal Structure Prediction from Powder X-Ray Diffraction Data Using Diffusion Models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Nofit Segal, Mingda Li, Benjamin Kurt Miller, Rafael Gómez-Bombarelli
Determining the crystal structure of a material from its powder X-ray diffraction (PXRD) pattern is a central challenge in materials science. PXRD is an accessible and widely used characterization technique, yet recovering the atomic structure from diffraction data requires solving an underdetermined inverse problem due to the loss of phase information. Generative modeling can provide a prior over atomic structure and learn the mapping from PXRD patterns to crystal structures via simulated structure-spectrum pairs. We present XRDiff, a diffusion model that recovers crystal structures from PXRD given either the stoichiometry or, in a more challenging setting, the elemental constituents and total number of atoms in the unit cell. We evaluate on datasets where each stoichiometry has multiple polymorphs and all polymorphs of a given composition are held out together, ensuring that high performance reflects genuine use of the diffraction signal. XRDiff achieves strong structure recovery rates on simulated benchmarks, indicating that the model learns a spectrum-to-structure mapping precise enough to differentiate between polymorphs. To address generalization to experimental data, we compare a full-spectrum encoding against an encoding based on peak descriptors. The peak-based encoding generalizes substantially better, outperforming even a model trained on full spectra with augmentations fitted to the experimental noise distribution. These results demonstrate that representations robust to the noise and artifacts present in real-world PXRD offer a practical and scalable path toward closing the simulation-to-experiment gap, enabling zero-shot crystal structure solution from experimental PXRD with full or partial chemical composition input.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
Symmetry of the critical current function in superconducting nanodevices
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-15 20:00 EDT
Ziqi Zhao, Cliff Sun, Ci-You Huang, Jiankun Zhang, Xiangyu Song, Alexey Bezryadin
We study a variety of nano-scale superconducting devices containing more than one weak link. Even in devices with multiple weak links the IB symmetry is usually obeyed, which means that if we reverse both the bias current direction and the magnetic field direction at the same time, the superconducting response, namely the critical current, remains unchanged. We also provide a detailed analysis of the situations in which such symmetry is violated.
Superconductivity (cond-mat.supr-con)
15 pages, 17 figures
General Theory for Ferroelectric Control of Spin Splitting in Collinear Antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Zhihao Dai, Yingwei Chen, Junyi Ji, Chaoyu He, Hongjun Xiang
Electrical control of magnetism is crucial for next-generation spintronics. While recent advances have demonstrated ferroelectric switching in two-dimensional magnets, a general design strategy spanning different dimensionalities remains elusive. Here, we develop a group-theoretical framework for achieving ferroelectric control of spin splitting in collinear antiferromagnets, including altermagnets and compensated ferrimagnets. By systematically classifying switching operators through symmetry analysis, we identify a universal pathway for the simultaneous reversal of electric polarization and nonrelativistic spin this http URL validate this approach in three representative systems: quasi-one-dimensional $ (6,14)$ Zigzag graphene nanoribbons, two-dimensional\ch{Nb3I8}, and three-dimensional altermagnetic\ch{MnSe2}. Our work establishes a versatile design paradigm for magnetoelectric devices and expands the functional landscape of low-power spintronic materials beyond the low-dimensional limit.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Topology-defined computation in knitted textiles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Mechanical computation, in which logic functions are realized through deformation rather than electronics, has been demonstrated in systems such as origami, kirigami, and mechanical metamaterials. In these systems, logic states and functions are typically determined by geometry and material properties, making it sensitive to deformation and imperfections. Here we introduce a mechanical computing architecture in which logic is defined by topology rather than geometry. The circuit is realized as a knitted textile formed from a single continuous yarn, where information is encoded in the topology of stitches and processed through controlled unraveling. By discretizing the textile into a lattice of interacting cells, we construct topological propagation rules that implement universal logic operations, including NOT, AND, and OR gates, as well as a half-adder. Experiments demonstrate that the logical output is robust against geometric deformation, while mechanical factors affect only if the computation can be executed. These results establish topology-defined computation as a model for information processing in textiles and other reconfigurable physical systems.
Soft Condensed Matter (cond-mat.soft)
10 pages, 7 figures
Field-selective criticality in 2D melting revealed by multi-field Lee-Yang zeros
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Ling Liu, Fang-Cheng Wang, Qi-Jun Ye, Xin-Zheng Li
How a two-dimensional solid melts remains unsettled after 60 years of study, as theory, model systems, simulations, and atomic-resolution experiments continue to suggest conflicting scenarios. The same transition can appear continuous or abrupt depending on how it is observed, where this ambiguity is especially acute in confined water. Here we study bilayer water under nanoconfinement and ask not only where its phase boundaries lie, but how the system responds to the two fields that drive them: temperature and lateral pressure. Using Lee-Yang zeros together with enhanced sampling, we find that some phase boundaries are field-selective: the two responses can differ either in continuity itself, or in how strongly they are rounded in finite systems. This distinction changes the two-step melting picture. The solid–hexatic transition is field-selective first-order, with the density channel remaining unusually rounded, whereas the hexatic–liquid transition becomes a conventional first-order transition once larger cells reveal a hidden bimodal enthalpy distribution. This framework organizes the apparent disagreement among confined-water simulations, hard-disk models and AgI experiments by identifying which thermodynamic channel each probe sees.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
10 pages, 3 figures
Altermagnetism and bond-nematicity in the spin-$1/2$ square lattice $J_1-J_2-δ$ model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-15 20:00 EDT
Tanja Đurić, Shenlong Yu, Pinaki Sengupta
We study appearance of bond-nematicity in insulating altermagnetic materials induced by increased frustration and quantum-fluctuations driven melting of the altermagnetic order. Using novel machine learning approach that combines symmetry enhanced neural network architectures and variational Monte Carlo we consider the spin-$ 1/2$ square lattice $ J_1-J_2-\delta$ model known to have altermagnetic ordering in the regime of small geometric frustration and a gapless spin liquid phase in the regime of strong frustration and small exchange interaction modulation parameter $ \delta$ . In the regime where exchange modulation is relatively large, resulting in the significant splitting of the magnon modes with different chiralities in the altermagnetic regime, we find that melting of the altermagnetic order by increased frustration leads to an intriguing phase that hosts coexisting symmetry protected topological valence bond solid and bond-nematic orders. The phase is characterized by condensation of magnon pairs that results in bond-nematicity, breaking of U(1) spin rotation and $ \mathbb{Z}_2$ spin inversion symmetries and chiral splitting of the triplon-like energy levels in the excitation spectrum. Whilst numerous recent studies address non-trivial impact of altermagnetic moments on various properties in altermagnetic materials, like electronic band structure and superconductivity, influence of strong quantum fluctuations and phases that can result from melting of the altermagnetic order are much less explored. Our study therefore presents an important step in identifying exotic phases of matter that can emerge in vicinity of the altermagnetic order.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 12 figures
Interface-engineered oxidation-resistant wafer-level Tantalum-Tantalum thermocompression bonding for 3D integration of superconducting interconnects
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-15 20:00 EDT
Harsh Mishra, Ullas Pandey, Sathish Bonam, Adirae Dinesh, Sai Rama Krishna Malladi, Shiv Govind Singh
Wafer-level 3D integration of superconducting interconnects requires low-thermal budget bonding processes compatible with superconducting materials. Rapid native oxide formation on tantalum (Ta) surfaces limits low-temperature, low-pressure direct Ta-Ta thermocompression bonding. In this study, we develop an oxidation-resistant bonding process using an ultrathin Au passivation layer to suppress oxide formation during bonding. The engineered interface enables blanket Ta-Ta wafer bonding at 300 $ ^\circ$ C under 4.93 bar, significantly reducing the bonding thermal budget and generation of $ \alpha$ -Ta across the interface, which potentially improves coherence time as reported in literature. Structural and interfacial analyses confirm oxide suppression and continuous metallic bonding, having a bond strength of 169 MPa. This work demonstrates a low-temperature, low-pressure Ta-Ta thermocompression bonding strategy for scalable 3D superconducting interconnect integration.
Superconductivity (cond-mat.supr-con)
6 pages, 7 figures
Probing Structure and Ionic Transport in Molten Lithium Carbonate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Debsundar Dey, Abhirup Patra, Anand Narayanan Krishnamoorthy, Gopalakrishnan Sai Gautam
Li$ _2$ CO$ _3$ (LC) is a cornerstone material for clean energy technologies, including high-temperature molten carbonate fuel cells, electrochemical carbon capture, and lithium-based batteries. However, capturing the complex, many-body interactions governing the structure and transport in LC in its molten state has remained a challenge, constrained by the computational cost of \textit{ab initio} methods and the accuracy limitations of classical force fields. To address this gap, we deploy equivariant graph-based machine learned interatomic potentials, specifically, the multi atomic cluster expansion (MACE) and neural equivariant interatomic potential (NequIP) architectures that are trained on melt-quench \textit{ab initio} molecular dynamics data. Our benchmarking demonstrates that MACE provides superior transferability and precision in predicting energies and forces compared to NequIP. Subsequently, we use the optimized MACE model to perform large-scale molecular dynamics simulations to probe the properties of molten LC. Besides describing the structural features, such as the dominant presence of C-O pair correlations under molten conditions, our MACE model reproduces experimentally-measured static structure factors and shear viscosity values. Further, our simulations indicate that Li transport in LC is fundamentally dominated by concerted motion, as evidenced by Haven’s ratios being significantly below unity (0.20-0.40). Notably, we identify a temperature-driven transition from anisotropic (and highly concerted) Li transport, supported by persistent oxygen-centered Voronoi cages at 1000K, to isotropic (and less concerted) diffusion at 1400K. Thus, we provide fundamental insights into the structural and transport properties of molten LC and also demonstrate a robust and scalable framework for the accelerated design of molten salt electrolytes and ionic liquids.
Materials Science (cond-mat.mtrl-sci)
Diffusion-driven autocatalytic dynamics on a sphere
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
We study the collective dynamics of independent particles that diffuse outside a spherical surface, on which they are replicated with a prescribed catalytic rate. In spatial dimensions three and higher, the transient nature of diffusion creates the competition between autocatalytic and escape events, thus leading to a rich phase diagram between subcritical (extinction), critical (steady-state), and supercritical (growth) regimes at long times. The rotational symmetry of the domain and an explicit form of the single-particle diffusion propagator allow us to obtain the statistics of the population size (i.e., the number of particles). In this way, we analyze the mean population size, its variance and higher-order moments, as well as the full distribution. In particular, we obtain a fully explicit form of the distribution at long times and describe a slow, power-law approach to this steady-state limit.
Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Fermi gas of polar molecules in the Pauli-blocked regime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-15 20:00 EDT
Junyu Lin, Annette N. Carroll, Phillip Martin, Calder Miller, Reuben R. W. Wang, Kevin Xu, John L. Bohn, Tim de Jongh, Jun Ye
Quantum gases of polar molecules have recently emerged as a powerful platform for exploring exotic many-body dynamics and correlated quantum behavior. To achieve the full potential of this platform, the production of deeply degenerate quantum gases of molecules in arbitrary confinement geometries is necessary. Here, we successfully evaporate fermionic KRb molecules in both 3D and quasi-2D geometries to well below their Fermi temperatures utilizing dipolar collisions. As we evaporate deeper into degeneracy in both geometries, we enter the Pauli-blocked regime with polar molecules, which we independently confirm for the first time by measuring the Pauli suppression of elastic collisions. Moreover, the Pauli suppression of collisions contributes to the limitation of our final molecular temperature to about 25% of the Fermi temperature in both geometries, particularly limiting quasi-2D evaporation where the Pauli blockade drastically reduces an otherwise large elastic to inelastic scattering ratio. This work demonstrates the production of degenerate Fermi gases of polar molecules both in a 3D harmonic trap and in mono- and bi-layer 2D configurations. Further, our work explores the fundamental limits on evaporation of molecular Fermi gases set by the Pauli-exclusion principle, which could be overcome in the future by introducing distinguishable scattering partners.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
21+26 pages, 4+11 figures
The Structure-tuning Magnetism in the Co(NbxTa1-x)2O6 Series
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Sirui Huang, Lun Jin, Yuchen Liu, Xiyu Chen, Leili Tan
Low dimensional quantum materials have been extensively studied within the physics community, among which Co2+ is one of the most popular magnetic ions to be embedded into the structural motif. CoNb2O6 and CoTa2O6 both have adopted an effective spin-1/2 state, with the former attracting enduring interest while the latter being rarely investigated. This difference can be attributed to their distinct crystal structures, not only in crystal systems, but more important, how the CoO6 octahedra are connected. We successfully merge these two compounds together and map out the doping limits. We find out Ta and Nb dopants modify the properties of the parent compounds in subtle but different ways and construct a magnetic phase diagram of the Co(NbxTa1-x)2O6 (0 < x < 1) series. In addition, our results suggest that Ta-doping may pave a way to strengthen the lower-dimensional quantum phenomena in CoNb2O6 before its crystal structure starts to melt down.
Materials Science (cond-mat.mtrl-sci)
Stochastic Thermodynamics on Time-Evolving Curved Spaces
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Rihito Nagase, Shoki Sugimoto, Asuka Takatsu, Takahiro Sagawa
We construct stochastic thermodynamics of overdamped Langevin systems on nonrelaticvistic curved spaces with time-dependent metrics. The time dependence of the metric contributes to the energy balance by performing work on the kinetic energy, which is instantaneously dissipated as heat in the overdamped regime. This contribution makes our framework thermodynamically consistent so that entropy production satisfies the second law of thermodynamics. As a special case, when the metric evolves according to backward Ricci flow, the entropy balance exhibits a structure similar to Perelman’s entropy functional. Our framework provides a way to quantify thermodynamic costs in dynamics on time-evolving spaces such as diffusion on membranes.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
(7+6) pages, 3 figures
Ferromagnetic Order of Reduced Magnetic Moments in a Frustrated Sawtooth Chain of the Magnetic Semiconductor ZnYb$_2$S$_4$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-15 20:00 EDT
Shinji Okada, Hiroto Suzuki, Nonoka Higa, Yasuyuki Shimura, Takanori Taniguchi, Takahiro Onimaru
In a sawtooth spin chain, competing nearest- and next-nearest-neighbor interactions suppress long-range order, yielding novel quantum states such as a spin-dimer singlet, 1/2 magnetization plateau, and spin contraction. Here, we investigate the magnetic properties of the orthorhombic semiconductor ZnYb$ 2$ S$ 4$ , in which Yb$ ^{3+}$ ions with an effective spin-1/2 form a sawtooth chain along the $ b$ -axis. The specific heat exhibits a sharp peak at $ {T}{\rm m}$ $ =$ 1.4 K, at which the magnetic entropy $ S{\rm m}$ reaches only 27% of $ R$ ln2. This reduced $ S_{\rm m}$ at $ T_{\rm m}$ indicates the entropy release of the ground state doublet of Yb$ ^{3+}$ even for $ T$ $ >$ $ T_{\rm m}$ . The isothermal magnetization $ M(B)$ at 0.28 K exhibits hysteresis for $ \left|B\right| \leq 0.2$ T and increases monotonically for $ B > 0.2$ T. The spontaneous magnetization is only 0.1 $ {\it \mu}{\rm B}$ /$ Yb, an order of magnitude smaller than that expected for the ground state doublet of Yb$ ^{3+}$ . Moreover, in powder neutron diffraction measurements, no superlattice reflections due to antiferromagnetic order are observed for $ T$ $ <$ $ T{\rm m}$ . Therefore, in the ground state, the Yb moments are ferromagnetically aligned, but their amplitude is reduced by magnetic frustration in the sawtooth Yb chain.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
6 pages, 6 figures
J. Phys. Soc. Jpn. 95, 074706 (2026)
Vapor-to-glass preparation of biaxially aligned organic semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Jianzhu Ju, Debaditya Chatterjee, Paul M. Voyles, Harald Bock, Mark D. Ediger
Physical vapor deposition (PVD) provides a route to prepare highly stable and anisotropic organic glasses that are utilized in multi-layer structures such as organic light-emitting devices. While previous work has demonstrated that anisotropic glasses with uniaxial symmetry can be prepared by PVD, here, we prepare biaxially aligned glasses in which molecular orientation has a preferred in-plane direction. With the collective effect of the surface equilibration mechanism and template growth on an aligned substrate, macroscopic biaxial alignment is achieved in depositions as much as 180 K below the clearing point $ T_{LC-iso}$ (and 50 K below the glass transition temperature $ T_g$ ) with single-component disk-like (phenanthroperylene ester) and rod-like (itraconazole) mesogens. The preparation of biaxially aligned organic semiconductors adds a new dimension of structural control for vapor-deposited glasses and may enable polarized emission and in-plane control of charge mobility.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
23 pages, 4 figures, SI included
J. Chem. Phys. 159, 211101 (2023)
Spin mixing induced dynamics of spinor solitons in $F=1$ Bose Einstein condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-15 20:00 EDT
T. Panagos, A. Romero-Ros, G.C. Katsimiga, P. Schmelcher, P.G. Kevrekidis
We explore soliton interactions in a homogeneous spinor $ F=1$ Bose Einstein Condensate (BEC) in the presence of a magnetic field, focusing on dark bright dark and bright dark bright configurations. We investigate how these interactions depend on the phase differences among bright solitons and their influence during the dynamics. Our findings align with prior non spinor results, i.e., repulsion among in phase bright solitons and attraction among out of phase pairs in self repulsive atomic BECs. The potential bright soliton attraction, added to the short range repulsion of dark dark soliton interactions, can lead to bound states. However, we find that these bound states break in the presence of spinor interactions due to the particle exchange dynamics between the hyperfine states of the components. Additonally, we develop an effective classical model to describe the soliton dynamics, using a Lagrangian approach. The accuracy of the model is tested by comparing it against numerical simulations. Our results suggest that the proposed model captures the essential features of soliton behavior in the presence of spin interactions, and provides congruent soliton trajectories and interspecies particle exchange dynamics in most of the cases.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
$p$-wave magnet and hedgehog-type Berry curvature in helimagnetic MnAu$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Hogyun Jeong, Sangyun Lee, Junhee Shin, Jung-Woo Yoo, Changhee Sohn, Yoon Seok Oh, Hosub Jin
Recently discovered altermagnetism in collinear compensated magnets shows even-parity spin texture in momentum space. Beyond the collinear spin ordering, unique odd-parity spin textures emerge in noncollinear compensated magnets. The noncollinear candidates, however, remain unexplored toward a room-temperature metallic altermagnet. Here, we demonstrate that MnAu2 exhibits metallic p-wave magnetism and large spin splitting induced by helical spin ordering. By adapting the band-unfolding scheme based on the translation operators combined with spin rotations, first-principles calculations reveal an unconventional Fermi surface around the $ \tilde{M}$ -point composed of a single electron pocket with $ p$ -wave spin texture. Moreover, the spin twist in the helimagnet triggers topologically non-trivial hedgehog Berry curvature, which links to the nonlinear Hall effect and spin Hall effect. Considering the experimental T$ _C$ = 335 to 370 K, MnAu$ _2$ could establish itself as an ideal candidate for a room-temperature metallic $ p$ -wave magnet, promising for versatile spintronic applications.
Materials Science (cond-mat.mtrl-sci)
Pronounced in-plane anomalous Hall effect with vanishing out-of-plane response in Cr1.2Te2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Wenzhi Peng, Zheng Liu, ShaSha Wang, Haolin Pan, Changlong Wang, Xiangbiao Shi, Jiahao Han, Qian Niu, Yang Gao, Bin Xiang, Dazhi Hou
We report an unconventional anomalous Hall regime in the van der Waals ferromagnet Cr1.2Te2, in which the anomalous Hall effect (AHE) is present for in-plane magnetization but absent for out-of-plane magnetization. In this purely in-plane regime, the anomalous Hall signal exhibits a threefold angular dependence during both in-plane and out-of-plane rotations of the magnetization, which cannot be accounted for by the conventional dipolar contribution but instead requires an octupolar contribution. Although the octupolar term qualitatively captures the observed behavior, the experimentally extracted octupole differs quantitatively from first-principles calculations based solely on the intrinsic Berry-curvature mechanism, indicating an essential role for extrinsic scattering processes.
Materials Science (cond-mat.mtrl-sci)
Thermodynamic Framework for $q$-Affinity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Dani Rodríguez-Castellanos, Petr Jizba
We develop a thermodynamic framework for non-equilibrium affinities based on generalized entropies. In particular, we extend the classical concept of De Donder by introducing $ q$ -affinities associated with Rényi and Tsallis entropies. This in turn allows us to generalize thermodynamic driving forces to systems with long-range interactions and/or strong correlations. For Rényi entropy, we build on a thermodynamic interpretation due to Baez, where the entropy is expressed through finite differences of the Helmholtz free energy at two temperatures. This leads to a generalized thermodynamic potential whose derivative with respect to a reaction coordinate defines the Rényi $ q$ -affinity. The resulting expression admits a representation in terms of exponential work averages, establishing a connection to Jarzynski-type fluctuation relations. For Tsallis entropy, we consider Markov jump processes using a master-equation-based approach. We derive a $ q$ -deformed entropy balance law and obtain an explicit expression for the Tsallis entropy production rate, proving its non-negativity and thus recovering a generalized second-law structure. This allows to identify a local stochastic $ q$ -affinity with the generalized thermodynamic force entering the entropy production rate.
Statistical Mechanics (cond-mat.stat-mech)
10 pages, no figures
Thinning-by-spinning: shear rheology of dense chiral fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Lucio Mauro Carenza, Giuseppe Gonnella, Demian Levis, Giuseppe Negro
We investigate the linear and nonlinear rheology of dense chiral fluids composed of self-spinning particles under external shear. Using particle-based simulations of a two-dimensional Lennard-Jones model with transverse interactions, we show that chirality acts as an intrinsic source of fluctuations and shear. In the solid regime, spinning fluidizes the system, weakening hexatic order. In the liquid regime, the viscosity is quantitatively described by a Green-Kubo relation upon replacing the temperature by a chirality-dependent effective temperature. Beyond linear response, flow curves collapse when expressed in terms of the ratio between imposed shear and spinning rates, revealing a thinning-by-spinning mechanism. At large forcing, this correspondence breaks down and a pronounced handedness asymmetry emerges: when transverse interactions oppose the imposed shear, stresses relax through the formation of string-like flow channels. Our results identify chirality as a generic mechanism for fluidization and provide a unified framework for understanding the rheology of dense chiral suspensions.
Soft Condensed Matter (cond-mat.soft)
Thermodynamic Bounds from Otto–Villani Functional Inequalities
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
The dissipation in the relaxation of an ensemble of conservative stochastic systems towards the steady state is quantified by the free energy difference. Functional inequalities within the framework of [F. Otto and C. Villani, J. Funct. Anal. 173, 361 (2000)] are here revisited which connect the free energy dynamics and optimal transport, offering a geometric perspective on the instantaneous speed of relaxation in the presence of potential barriers. These are illustrated with numerical relaxation experiments on Landau-Ginzburg potentials.
Statistical Mechanics (cond-mat.stat-mech)
Mass-imbalanced two-dimensional Bose-Fermi mixtures with boson-fermion pairing
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-15 20:00 EDT
Cristiano Luigi Kosman Chiarappa, Pietro Bovini, Pierbiagio Pieri
We analyze a two-dimensional Bose-Fermi mixture at zero temperature in the presence of a tunable Bose-Fermi attraction. We adopt a diagrammatic T-matrix approach and study the behavior of several thermodynamic quantities for the two species as functions of density, mass ratio, and coupling strength. These include the chemical potentials, the boson momentum distribution function, the condensate density, and Tan’s contact parameter. We analytically demonstrate that the present T-matrix formalism recovers the correct second-order perturbative expansion of the chemical potentials in the weak-coupling regime, and test it numerically. The near-universal behavior already found in prior work for the mass-balanced case is confirmed for different masses and becomes even more accurate when the boson mass is large. The mass imbalance emerges as an additional control parameter that qualitatively affects the bosonic momentum distribution. In particular, we found that it can be used to allow for the experimental observation of a peculiar peak in the boson momentum distribution at finite momentum.
Quantum Gases (cond-mat.quant-gas)
17 pages, 15 figures
Modeling light-matter coupled systems with neural quantum states
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-15 20:00 EDT
Noe Salmeron, Marin Bukov, Markus Schmitt
Recent advances in cold atom manipulation enable the study of many-body systems where short-range interactions between neighboring atoms coexist with long-range interactions mediated by photons. Such a combination of interactions makes a theoretical approach challenging beyond mean-field methods. In this work, we develop a neural quantum state based approach to study these systems numerically. We introduce a neural-network architecture capable of handling hybrid Hilbert spaces with large local bosonic dimensions in strongly interacting spin-photon systems. We benchmark this approach on a model of a two-dimensional lattice of Rydberg atoms coupled to a photon mode. The superradiant ground states found in the large spin-photon coupling regime allow us to demonstrate the efficiency of the method in the presence of high photon occupation. Furthermore, the ability to capture spin-spin and spin-photon correlations leads us to observe quantitative deviations in the ground state phase boundaries with respect to mean-field theory. The method extends to other systems with a similar hybrid Hilbert space structure, such as spin-phonon systems, and provides a scalable framework for investigating their ground state properties.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
15 pages, 8 figures, The data associated with this manuscript version is available under DOI:https://doi.org/10.5281/zenodo.20630702
Spherical metadensity functional learning for inhomogeneous classical fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Stefanie M. Kampa, Matthias Schmidt, Florian Sammüller
We develop classical density functional learning to address fluids with truncated pairwise interparticle interactions in three-dimensional spherical geometry. Simulation data for systems with randomized repulsive pair potentials provide the basis for supervised training of a neural metadensity functional, thereby making efficient use of results for radial distribution functions in the bulk fluid via the test particle route. Specifically, we develop spherical local learning in order to represent the one-body direct correlation functional in terms of a neural network, which captures spatial curvature effects as well as the metadensity functional dependence on the thermally scaled pair potential. The framework yields efficient access to inhomogeneous structuring and related physical phenomena that occur in fluids and general solvents when adsorbed against curved solutes and confined inside of spherical and planar cavities. Test particle setups facilitate accurate prediction of the bulk fluid pair structure and verification of thermodynamic test particle sum rules via functional line integration. Applying the metadensity functional for Henderson inversion allows one to infer accurately the pair potential from the bulk radial distribution function. We address implications of the geometrical setup for two-body quantities and obtain the two-body direct correlation functional from automatic differentiation. For the hard sphere fluid, we confirm metadensity functional predictions against results from a standard neural density functional with fixed pair potential as well as to an analytic functional as given by fundamental measure theory. Simulation results provide further reference and corroborate reliable results of the spherical neural metadensity functional across a broad range of applications.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
18 pages, 11 figures
Bond-operator analytical approach for the $t$-$J$ model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-15 20:00 EDT
We present a bond-operator theory (BOT) for analytical consideration of the $ t$ -$ J$ model and its extensions with longer-rage hopping terms. This technique is based on previously suggested representation of electron operators via localized spins 1/2 and spinless Fermi-operators of mobile holons which requires no constraint between them. We introduce a representation of operators of spins, holons, and electrons in (extended) unit cell containing several lattice sites via a zoo of Bose- and Fermi-operators acting in the Hilbert space of all quantum states of the whole unit cell. BOT provides a regular expansion of physical quantities in powers of $ 1/n$ using conventional diagrammatic technique, where $ n\ge1$ is the maximum number of introduced quasiparticles (bosons and fermions) which can occupy a unit cell. The suggested representation reproduces commutation algebra of all operators at any $ n>0$ and allows to consider both magnetically ordered and disordered phases. Some elementary excitations described in the BOT by separate bosons or fermions appear in common approaches as bound states of conventional quasiparticles. In particular, there are two-hole bound states (Cooper pairs of two holes) which are described within the BOT by separate bosons. We discuss in detail properties of the $ t$ -$ J$ model on the square lattice with no more than two holes (polarons). Although the expansion parameter $ 1/n$ is not small in the physically meaningful case of $ n=1$ , we obtain a good quantitative agreement with previous numerical findings at $ n=1$ even in the first order in $ 1/n$ after taking into account a few simple diagrams. Self-consistent calculations in the first order in $ 1/n$ bring our results to a very good quantitative agreement with previous numerical findings of the ground state energy, staggered magnetization, and spectra of magnons, polarons, and lowest-energy two-hole bound states.
Strongly Correlated Electrons (cond-mat.str-el)
22 pages, 12 figures
Multistate Manipulation of Charge-Spin Conversion in Two-Dimensional Ferroelectric Bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Weiyi Pan, Xinyuan Jiang, Jaroslav Fabian
Achieving nonvolatile and multistate manipulation of charge-spin conversion, including the Edelstein effect (EE) and spin Hall effect (SHE), is crucial for high-density spintronic memory. Here, we propose a mechanism to simultaneously control both EE and SHE in two-dimensional ferroelectric bilayers, where interlayer-parallel and interlayer-antiparallel polarization configurations can coexist. Symmetry analysis shows that in the interlayer-parallel states, reversal of the total polarization switches the sign of the EE, whereas changing to an interlayer-antiparallel configuration suppresses the EE to zero, enabling electrically switchable current-induced spin accumulation among three distinct states, which could be used for ternary logic operations. Meanwhile, the magnitude of the SHE can be tuned by switching between two different classes of polarization configurations, namely interlayer-parallel and interlayer-antiparallel configurations. Using first-principles calculations, we demonstrate this mechanism in bilayer metallic ferroelectric PtBi2, where both interlayer-parallel and interlayer-antiparallel polarization configurations are energetically stable. The EE coefficient in interlayer-parallel states, which can be reversed by polarization switching, arises from competing electron- and hole-pocket contributions near the Fermi surface. The intrinsic SHE coefficients originate from spin Berry curvature that can be reshaped by polarization configuration variation and Fermi-level tuning. Our results establish ferroelectric bilayers as an all-in-one platform for electrically programmable charge-spin conversion.
Materials Science (cond-mat.mtrl-sci)
The Future of Computing for Materials Science Challenges
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Phalgun Lolur, Richard P. Padbury, George H. Booth, Katherine Inzani, Nicole Holzmann, Thomas W. Keal, Joseph Montaya, Daniel F. Urban, Thomas Eckl, Emanuele Marsili, Wibe A. de Jong, Jonathan R. Owens, Julian van Velzen
Materials discovery increasingly relies on the coordinated use of theory, computation, experiment, data-driven methods, and emerging quantum technologies, yet the full potential of these tools is realised only when they operate within workflows that reflect the complexity of real systems. This perspective summarises current capabilities, limitations, and opportunities across these domains, drawing on contributions from academia, industry, and national laboratories to identify the scientific and structural requirements for more reliable and efficient discovery. Classical simulations provide broad coverage across design spaces, while experimental measurements reveal degradation, heterogeneity, and kinetic processes that determine performance under realistic conditions. Machine learning accelerates exploration when supported by well-curated datasets with clear provenance and uncertainty quantification, and quantum computing offers promising routes into correlated electronic behaviour when aligned with properties that influence engineering decisions. Collectively, these insights highlight the need for reproducible workflows, shared data standards, realistic benchmarks, and a research culture that prepares scientists to work across paradigms. By integrating these methodological and organisational elements, the community can move toward discovery processes that deliver robust predictions, support confident decision making, and shorten the path from conceptual design to deployable materials.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
27 pages with supporting info, 3 figures
Local Coverage Governs Memorization in Diffusion Models
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-15 20:00 EDT
Claudia Merger, Sebastian Goldt
Memorization in diffusion models is often treated as a global property of the model or dataset. In practice, however, a single diffusion model can simultaneously generate both memorized and novel samples. Which training samples are most likely to be memorized? In this work, we show that memorization is governed by \emph{local data coverage}. Leveraging the connection between diffusion models and kernel density estimation (KDE), we derive a theoretical criterion that predicts whether a point is memorized based on the density of training data in its neighborhood and the size of the training dataset. In the high-dimensional limit, this leads to a sharp, local transition: regions of low coverage are dominated by isolated training samples, which are memorized, while dense regions support interpolation and generalization. We validate these predictions empirically, showing that memorization increases with local sparsity and that diffusion models exhibit a coexistence of memorized and novel samples within the same model. Extending this framework to multi-class settings, we further show that classes with higher intra-class sparsity (and thus lower local coverage) are more strongly memorized. Our results provide a local view of memorization in diffusion models, explaining when and where memorization occurs in terms of data geometry.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (stat.ML)
Modifying Electrochemical Doping in Light-Emitting Electrochemical Cells with Gold Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Ajay K. Poonia, Anton Kirch, Joan Ràfols-Ribé, Lucrezia Catanzaro, Anish Rao, Karol Kołątaj, Vittorio Scardaci, Giuseppe Compagnini, Guillermo P. Acuna, Ludvig Edman, Nicolò Maccaferri
Electrochemical doping offers dynamic control of the electronic properties of organic semiconductors, and it is the enabling feature of a range of technologies, including electrochemical transistors, energy-storage devices, light-emitting electrochemical cells (LECs), and bioelectronics. Electrochemical doping is commonly controlled by the selection of the constituents in the active material of the device or the applied voltage bias, but herein we report that the incorporation of Au nanoparticles (Au-NPs) at an electrode interface can constitute an alternative control parameter. The LEC features balanced p- and n-type electrochemical doping that forms a p-n junction doping structure in its active material, and we find that it is possible to reshape this doping profile by incorporating Au-NPs at an electrode interface. Specifically, we establish that the inclusion of neat non-capped Au-NPs at the anodic interface shifts the p-n junction (i.e., the emission zone) away from the anode. In contrast, the inclusion of Au-NPs capped with sodium citrate is found to reverse this behavior, so that the emission zone is instead moved towards the anode. We utilize this control parameter to shift the emission zone towards a position of constructive (destructive) interference, as manifested in a strong increase (decrease) of the LEC emission efficiency. Our findings establish an interfacial strategy for modulating the spatial profile of electrochemical doping and tuning device performance without altering the chemistry of the active material, relying instead on the surface modification of one electrode. This approach is important because it provides a versatile and minimally invasive route to optimize electrochemical devices while preserving the intrinsic properties and formulation of the active material.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Strain- and doping-tunable optical resonance in Kekulé-Y graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
We investigate the optical response of Kekulé-Y graphene under uniaxial strain and carrier doping. Using a low-energy effective Hamiltonian, we show that strain reshapes the low-energy electronic structure of the Kekulé-Y phase and induces Van Hove singularities at energies well below those of pristine graphene. Within the Kubo formalism, we calculate the optical conductivity and identify multiple anisotropic interband features, with a pronounced resonance arising from strain-induced Van Hove singularities. The pronounced resonance is strongly anisotropic and robust against moderate thermal broadening and disorder, providing a clear optical signature of Kekulé-Y ordering. We further derive analytical expressions for the low-energy optical conductivity and the Drude weight, providing a detailed characterization of the strain- and doping-dependent optical response. Our results establish strain engineering as an effective route for controlling valley-dependent optical properties in Kekulé-Y graphene, originating from the Kekulé-induced coupling of the Dirac valleys, and suggest feasible optical probes for the experimental identification of the Kekulé-Y phase.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 11 figures
Phys. Rev. B 113 (2026) 165406
SmoQyElPhQMC.jl: An open-source Julia package for efficient and scalable quantum Monte Carlo simulations of electron-phonon coupled models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-15 20:00 EDT
Benjamin Cohen-Stead, James Neuhaus, Kipton Barros, Thomas A. Maier, Steven Johnston
We introduce version 1.0 of the SmoQyElPhQMC package, an open-source Julia code for performing scalable quantum Monte Carlo simulations of electron-phonon coupled model Hamiltonians. SmoQyElPhQMC is built upon the SmoQyDQMC codebase and implements improved versions of the algorithms presented in [B. Cohen-Stead \textit{et al}., Phys. Rev. E {\bf 105}, 065302 (2022)] to enable linear-scaling simulations of a broad class of uncorrelated $ e$ -ph models both in system size and inverse temperature. By extending the functionality of the flexible scripting interface introduced in SmoQyDQMC, the SmoQyElPhQMC package continues to allow users to adapt it to different workflows and interface with other software packages in the Julia ecosystem. The code for this package can be downloaded from our GitHub repository at this https URL or installed using the Julia package manager. The online documentation, including examples, can be obtained from our documentation page at this https URL.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Planned submission to SciPost Codebases, comments welcome
On-chip superconducting GHz RF reflectometry of the capacitance response in bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
Sung Jin An, Minseo Cho, Minjun Park, Dohun Kim, HyeonJeong An, Seung-Bo Shim, Hakseong Kim, Sunghun Lee, Myoung-Jae Lee, Kenji Watanabe, Takashi Taniguchi, Jungpil Seo, Myunglae Jo, Youngwook Kim, Minkyung Jung
In dual-gated bilayer graphene, a perpendicular displacement field opens a band gap that modifies both the channel conductance and the electronic compressibility, motivating measurements that resolve resistive and capacitive responses on the same device. We integrate an hBN-encapsulated bilayer graphene heterostructure with an on-chip superconducting Nb lumped-element LC resonator and carry out RF reflectometry near 4.25 GHz. DC transport and finite-bias spectroscopy on the same device provide a transport reference. Top and bottom gates independently set the carrier density and displacement field. The DC and RF gate maps share the same gate-dependent features, with finite-bias measurements revealing a region of suppressed conductance whose bias extent grows with the displacement field, consistent with a field-induced gap. The gate-dependent resonance-frequency shift is converted to the effective capacitance seen by the resonator using an equivalent-circuit model. The capacitance shows a minimum near the conductance-suppressed region, consistent with reduced electronic compressibility in the gapped bilayer graphene, and exhibits an electron-hole asymmetry. The on-chip configuration probes the gate-dependent admittance of a dual-gated van der Waals heterostructure, providing capacitance-sensitive information that complements DC transport within a single device.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
20 pages, 4 figures
Generic nonlocal statistics of the stationary measure in conserved active systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Filippo De Luca, Michael E. Cates, Cesare Nardini
The stationary measure of equilibrium systems with detailed balance follows a Boltzmann distribution, so that for short-ranged interactions the measure is local, meaning that distant spatial domains are statistically independent. In contrast, active systems break detailed balance, and can have nonlocal stationary measure even for fully local dynamics. Here, by expanding in nonlinearity about a Gaussian-model limit, we construct the measure perturbatively deep in the disordered phase for a class of models that includes Active Model A, Active Model B+, Model AB, the Nonreciprocal Cahn–Hilliard model, and the Toner–Tu model. In this regime, nonlocality is linked to a dynamical conservation law. Our results generically preclude construction of a Landau–Ginzburg expansion of the stationary measure (as opposed to the dynamical equations) for conserved active field theories.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
9 pages (main text) + 13 pages (supplemental material), 2 figures
Spin-orbit coupling by design in quantum state engineering of atomically defined quantum dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
Hermann Osterhage, Julian H. Strik, Ivan Ado, Anna M. H. Krieg, Daniel Wegner, Mikhail Titov, Alexander A. Khajetoorians
Tuning spin-orbit coupling is essential in controlling both spin and charge in confined semiconductor nanostructures, yet it is rarely a truly controllable parameter. Here, we show control over the spin-orbit Hamiltonian in quantum dots and the resulting quantum states by tailoring the confinement potential with atomic-scale precision. Using scanning tunnelling microscopy and spectroscopy, we pattern individual Cs ions into designer quantum dot structures on the surface of indium antimonide, in which electrons from a two-dimensional electron gas are confined with chosen in-plane electric-field gradients. We then quantify the atomic level structure, both spatially resolving the orbital character of the electronic states and their magnetic-field evolution. We demonstrate that the level structure, including the induced zero-field splitting, can be tailored by the designed geometry of the local electric fields. These effects can be described using a Hamiltonian that allows consistent treatment of the confinement-induced spin-orbit coupling beyond the conventional Bychkov-Rashba description. This Hamiltonian is derived from a multiband k.p model and takes the energy dependence of the relevant physical parameters into account. Such precise control of spin-orbit coupling in semiconductor quantum dots is relevant to quantum and spintronic technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Extending Covariant Fluctuation Theorems into Quantum Regime through Quasiprobability Approach
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Ji-Hui Pei, Tingzhang Shi, Jin-Fu Chen, H. T. Quan
The covariant formulation of stochastic thermodynamics requires treating the stochastic work as a 4-vector, posing significant challenges for quantum systems due to the non-commutativity. We introduce a new quasiprobability distribution for the work 4-vector, which combines the Wigner and Margenau-Hill quasiprobabilities. This extends the covariant fluctuation theorems from classical to quantum regime. We illustrate our findings with a scalar field driven by classical particles with a generalized version of trace formula. Our work establishes a quasiprobability approach to studying relativistic quantum thermodynamics in a covariant way.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Boltzmann-Like Occupation of Nonequilibrium Steady States on Dense Networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
A central problem in statistical physics is to extend the Boltzmann distribution to nonequilibrium steady states (NESS). We prove that NESS on large dense networks have Boltzmann-like occupation despite extensive entropy production. We further show that the active-matter heuristic of “low rattling” is asymptotically exact. Intuitively, these NESS spend a greater fraction of their time in states they leave more slowly. This explanation extends to the broader class of “equiaccessible” steady states, which play a role in our analysis akin to that of equilibrium in linear response.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Probability (math.PR)
7 pages, 3 figures
Bacterial adhesion to curved surfaces in fluid flow
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Edwina F. Yeo, Benjamin J. Walker, Philip Pearce, Mohit P. Dalwadi
Minimising bacterial surface adhesion and subsequent biofilm formation in industrial and medical settings requires understanding how bacteria are transported and adhere to complex surface geometries in the presence of non-uniform flow. In this paper, we consider the transport of a dilute suspension of motile bacteria through a corrugated two-dimensional channel with perfectly adhesive walls. We asymptotically analyse the diffusive boundary layer that forms in high velocity flows using a curvilinear coordinate system based on the fluid streamfunction, presenting a similarity solution to the diffusivity-varying diffusion-type equation that arises. From this solution, we derive an analytical expression for the bacterial adhesion rate as a function of surface arclength and the spatially varying wall shear rate. Our model predicts that bacterial adhesion becomes localised on curved surfaces, with bacteria showing preferential adhesion to wall peaks' at lower shear rates and preferential adhesion to wall valleys’ at higher shear rates. More broadly, our results highlight how spatially varying flows generated by complex geometries can lead to localised bacterial adhesion, with potential implications for both enhancing and minimising biofilm formation.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
First-principles calculations of internal conversion processes in spin defects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Stefano Paolo Villani, Yu Jin, Giulia Galli
Optically active spin defects are foundational for quantum technologies, yet common approximations underestimate their internal conversion (IC) rates by orders of magnitude. We propose a broad, predictive framework to compute IC rates that incorporates multi-configurational effects via many-body wavefunctions in TDDFT, and includes all-phonon-mode contributions via analytical non-adiabatic couplings. Our approach resolves discrepancies with experiment, achieving quantitative agreement for the NV$ ^-$ center in diamond, and identifying a previously overlooked non-radiative channel in the divacancy triplet lifetime in SiC.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Main: 9 pages, 4 figures. Supplementary: 10 pages, 6 figures
On the physical meaning of latent track boundaries in swift heavy ion irradiated polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Adil Tuleushev, Fiona Harrison, Maxim Zdorovets
A large body of experimental studies of swift heavy ion latent tracks in dielectric materials has produced a wide range of estimates of track size. We investigate the physical meaning of these estimates by examining the different criteria of track boundary probed by various experimental techniques, including SAXS, XRD, chemical etching and conductometry. We show that different methods probe different physical aspects of ion induced modification, such as electron density redistribution, molecular ordering, chemical reactivity and charge separation, resulting in different determinations of effective track boundaries. Particular attention is paid to polymer films with electret-like properties, where post irradiation redistribution of weakly bound electrons may play an important role in the evolution of latent track structure.
Soft Condensed Matter (cond-mat.soft)
Tailoring the properties of YBa${2}$Cu${3}$O$_{7-δ}$ thin films by 30 keV He$^+$ irradiation: An enabling route to superconducting device nanopatterning
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-15 20:00 EDT
Bernd Aichner, Simon Koch, Philipp A. Korner, Max Karrer, Katja Wurster, Christoph Schmid, Ulrich Kentsch, Reinhold Kleiner, Edward Goldobin, Dieter Koelle, Wolfgang Lang
Focused helium ion beam (He-FIB) irradiation with 30 keV ions is a key tool for nanoscale patterning and defect engineering in high transition temperature (Tc) cuprate superconducting devices, yet its usable fluence window is constrained by the competing requirements of reliable superconductivity suppression and minimal structural degradation. In this work, we provide a comprehensive dataset on the effects of large-area 30 keV He+ ion exposure on the electric transport and superconducting properties of epitaxial YBa2Cu3O7 (YBCO) thin films. X-ray diffraction shows a fluence-driven loss of crystalline order accompanied by an out-of-plane lattice expansion and an orthorhombic-to-tetragonal transition, culminating at predominant amorphization at the highest fluence of 1 x 10^16 cm^-2. Raman spectra exhibit increasing disorder while lacking signatures of oxygen depletion, indicating that irradiation mainly generates oxygen-related Frenkel defects rather than changing the carrier concentration. Consistently, with increasing fluence, the normal-state resistivity \rho_N(T) at temperature T above Tc increases strongly, while d \rho_N/d T remains nearly unchanged at moderate fluence. The suppression of Tc is accurately described by Abrikosov-Gor’kov pair breaking and reaches complete quenching of superconductivity at 4.5 x 10^15 cm^-2. The anisotropic upper critical fields decrease approximately exponentially with increasing fluence, the vortex activation energy is reduced, and the anisotropy drops, in contrast to oxygen-depleted YBCO. Hall-angle analysis confirms a nearly constant carrier density but a systematic increase in defect scattering and reduced mobility, consistent with a crossover toward the dirty limit at high fluence. These results establish quantitative fluence thresholds and a practical operational window for He-FIB nanopatterning of YBCO quantum circuits.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
15 pages, 6 figures, 1 table
Lattice dynamics and the spectroscopic signatures of H-bond disorder in $δ$-AlOOH
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-15 20:00 EDT
Chenxing Luo, Sangjoon Lee, Hongjin Wang, Zhen Zhang, Renata Wentzcovitch
Raman and infrared anomalies associated with H-bond symmetrization in $ \delta$ -AlOOH, including mode softening and linewidth broadening at 5-10 GPa, occur at significantly lower pressures than predicted by static harmonic theory. To resolve this discrepancy, we combine harmonic phonon calculations with strongly constrained and appropriately normed (SCAN)-based deep-potential molecular dynamics and phonon quasiparticle analysis at 300 K. This framework extracts temperature- and pressure-dependent frequencies and lifetimes from long-time trajectories, capturing the branch reorganization and rapid linewidth growth characteristic of the disordering regime. Incorporating quasiparticle renormalization and directional longitudinal-optical-transverse-optical (LO-TO) splitting further yields near-quantitative agreement with the ambient-pressure OH-stretching Raman multiplet. These results identify finite-temperature dynamical effects and the progressive loss of spectral coherence as the origin of the spectroscopic signatures of H-bond symmetrization.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph), Geophysics (physics.geo-ph)
12 pages, 6 figures; Supplemental Material: 5 pages, 4 figures
Open Wilson chain numerical renormalization group approach to steady-state non-equilibrium quantum transport
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-15 20:00 EDT
Anand Manaparambil, Frithjof B. Anders
The numerical renormalization group (NRG) approach was developed to identify and quantify different equilibrium regimes of quantum impurity systems (QISs) with unprecedented accuracy by a tailored finite size representation. Out of equilibrium, the steady-state density operator is not of the Boltzmannian form but one that is determined by the imposed boundary conditions. We extend the NRG to the nonequilibrium setting by augmenting each Wilson site with a reservoir, whose coupling functions are calculated via a continuous fraction expansion in order to recover the continuum limit exactly. The nonequilibrium parameters such as a finite bias as well as a finite temperature gradient enters through the Bloch-Redfield tensor (BRT), whose zero eigenvector gives the steady-state density operator. We used the resulting open chain full density matrix (OC-FDM) approach with an effective single lead description to investigate the charge and spin transport through a quantum dot (QD) under finite bias and temperature gradient. The influence of lead asymmetry and an external magnetic field on the transport properties are also studied. For completeness, we have also investigated local properties of the QD, such as charge fluctuations and find excellent agreement with real-time quantum Monte Carlo (RT-QMC) data. The OC-FDM approach was able to explore Kondo energy scales as low as $ T_K/D \approx 10^{-8}$ in the non-equilibrium regime, as well as show convergence with the established equilibrium benchmarks, such as a quantitative agreement with full density matrix numerical renormalization group (FDM-NRG) and Fermi-liquid scaling at small bias and temperature. Owing to the effective single lead description, a single OC-FDM data point takes orders of magnitude less time on a standard laptop, compared to other state-of-the-art numerical methods.
Strongly Correlated Electrons (cond-mat.str-el)
22 pages, 17 figures
Generic long-range correlations in nonequilibrium mixtures
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-15 20:00 EDT
Jessica Metzger, Yariv Kafri, Mehran Kardar, Julien Tailleur
We study correlation functions in generic non-equilibrium mixtures, including multi-temperature systems and non-reciprocal field theories. The corresponding linear theory is short-ranged, and nonlinearities are irrelevant in the renormalization-group sense. Nonetheless, we find that these nonlinearities generate long-ranged three-point correlations in the isotropic disordered phase. Our analytical predictions, which are based on a phenomenological theory, are confirmed by numerical simulations of Brownian colloids in contact with thermal baths at different temperatures. Dangerously irrelevant nonlinearities in non-equilibrium mixtures thus offer a new route to long-range correlations, supporting the hypothesis that such correlations are not the exception but the rule out of equilibrium.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
7 pages, 2 figures
Percolation of a rod-like particle in a static bed of spheres: trapping and passing
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Juan C. Petit, Julio M. Ottino, Richard M. Lueptow, Paul B. Umbanhowar
We numerically investigate percolation of independent frictionless glued-sphere rod-like particles under gravity through a disordered static bed of larger spheres. We identify two distinct regimes: a \emph{trapping} regime, where rods stop after percolating a limited distance in the bed and a \emph{passing} regime, where rods percolate continuously with constant mean velocity. The transition between these regimes is governed by the length of the rod and the geometrical trapping threshold for spherical particles based on the rod diameter and the minimum pore throat diameter defined by three touching large spheres. The percolation velocity for all rod geometries, including the single sphere limit, collapses onto a single curve when scaled with the gravitational acceleration and the bed sphere diameter. The results also demonstrate that short rods percolate nearly twice as fast as long rods due to the geometric constraints associated with the disordered pore structure of the static bed. Consequently, long rods are more susceptible to trapping via specific contact configurations with the bed spheres, which differ from those for short rods. These results reveal how shape anisotropy introduces dynamical constraints and thresholds in granular percolation, with implications for predicting segregation in mixtures of non-spherical particles.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
13 pages, 16 figures
Interfacial mass transfer resistance at fluid-fluid interfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-15 20:00 EDT
Hyeongjoo Row, Brandon J. Wallace, Joshua B. Fernandes, Kevin R. Wilson, Kranthi K. Mandadapu
Complex chemistry in nano- and microscale compartments is often governed by how quickly reagents transit a fluid-fluid interface. Mass transport across interfaces is commonly modeled by assuming local equilibrium, enforcing continuity of chemical potential across the interface. While adequate at large scales, this approximation may break down at the microscale, where interfacial processes can become rate-limiting. Here, we extend linear irreversible thermodynamics to describe nonequilibrium interfacial mass transport. We identify an interface-limited regime, in which transport is governed by interfacial resistance and exhibits exponential relaxation. Combining microfluidic and spectroscopic techniques, we introduce an experimental technique that explores this regime and provides a direct measurement of the interfacial mass transfer coefficient. For a model system consisting of acetonitrile transport across a surfactant-stabilized water-oil interface, we obtain an interfacial transport coefficient $ {M \sim 7,{\rm nm/s}}$ . These results establish interfacial mass transfer resistance as a governing mechanism in microscale transport and provide a framework to predict, control and measure mass transport in multiphase systems at microscale.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
Quantum geometrical description of hole spin qubits far away from the $Γ$-point
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
Zoltán György, Dmitry Miserev, Jelena Klinovaja, Daniel Loss
Hole spin qubits provide one of the leading platforms for spin-based quantum computing due to their large intrinsic spin-orbit interaction (SOI), which enables fast electrical manipulation. The SOI of planar quantum dots has mostly been investigated in theoretical studies by examining the SOI already present in the two-dimensional hole gas (2DHG). Here, we study the SOI created by the in-plane confinement by deriving non-perturbative effective Hamiltonians numerically for hole spin qubits. We find that the quantum geometry of the 2DHG naturally emerges, leading to a meaningful non-perturbative definition of pseudospin valid far away from the $ \Gamma$ -point. The SOI of the 2DHG and of the in-plane confinement have different forms; therefore, they cannot be turned off simultaneously, ruining the perfect spin-orbit switch functionality of spin qubits. We construct effective Hamiltonians using the symmetry approach for various low-dimensional hole systems: (i) a heavy-hole confined in a SiGe/Ge/SiGe heterostructure, (ii) a light-hole confined in SnGe/Ge, (iii) a gate-defined nanowire in SiGe/Ge/SiGe, and (iv) a hole confined in a Ge/Si core/shell nanowire. The non-perturbative effective Hamiltonians provide results with excellent agreement with the full Hamiltonians.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
29 pages, 32 figures
Monolithic hybrid quantum dot devices in superconducting twisted bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-15 20:00 EDT
Alexandra Mestre-Torà, Marta Perego, Clara Galante Agero, Takashi Taniguchi, Kenji Watanabe, Thomas Ihn, Klaus Ensslin, Artem O. Denisov
Gate-tunable superconductivity in magic-angle twisted bilayer graphene (MATBG) has enabled the realization of superconducting devices, such as Josephson junctions, within a single crystal. This interface-free platform provides a reconfigurable and scalable architecture that overcomes limitations of conventional superconducting-semiconducting systems. Incorporating single-electron control enables access to regimes in which flat-band superconductivity competes with strong Coulomb repulsion, providing a platform for studying correlated physics phenomena. Here, we report a new class of quantum devices that combines electrostatic confinement with tunable superconductivity in a monolithic MATBG architecture. Within a single device, we demonstrate two complementary hybrid systems: superconducting islands and proximitized quantum dots. The superconducting island exhibits $ 2e$ -periodic transport, indicating a well-defined gap protected against quasiparticle poisoning. The proximitized quantum dot hosts subgap Andreev states together with a strongly parity-modulated supercurrent.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)