CMP Journal 2025-08-25
Statistics
Nature Materials: 3
Nature Physics: 1
arXiv: 52
Nature Materials
Quantum oscillations in a dipolar excitonic insulator
Original Paper | Bose-Einstein condensates | 2025-08-24 20:00 EDT
Phuong X. Nguyen, Raghav Chaturvedi, Bo Zou, Kenji Watanabe, Takashi Taniguchi, Allan H. MacDonald, Kin Fai Mak, Jie Shan
Quantum oscillations in magnetization or resistivity are a defining feature of metals in a magnetic field. The phenomenon is generally not expected in insulators without a Fermi surface. Its observation in Kondo and other correlated insulators provided counterexamples and remains poorly understood. Here we report the observation of resistivity oscillations in a gate-controlled excitonic insulator realized in Coulomb-coupled electron-hole double layers. When the electron or hole cyclotron energy is tuned to exceed the exciton binding energy, recurring transitions arise between the excitonic insulator and layer-decoupled quantum Hall states. Compressibility measurements show an oscillatory exciton binding energy as a function of the magnetic field and electron-hole pair density. Coulomb drag measurements further reveal the signature of finite-angular-momentum excitonic correlations. These findings are qualitatively captured by mean-field calculations. Our study establishes a highly tunable platform based on electron-hole double layers for studying quantum oscillations in correlated insulators.
Bose-Einstein condensates, Quantum fluids and solids, Quantum Hall, Two-dimensional materials
Competition between excitonic insulators and quantum Hall states in correlated electron-hole bilayers
Original Paper | Quantum fluids and solids | 2025-08-24 20:00 EDT
Ruishi Qi, Qize Li, Zuocheng Zhang, Jiahui Nie, Bo Zou, Zhiyuan Cui, Haleem Kim, Collin Sanborn, Sudi Chen, Jingxu Xie, Takashi Taniguchi, Kenji Watanabe, Michael F. Crommie, Allan H. MacDonald, Feng Wang
Excitonic insulators represent a unique quantum phase of matter that enables the study of exotic quantum bosonic states. Strongly coupled electron-hole bilayers, which host stable dipolar exciton fluids with an exciton density that can be adjusted electrostatically, offer an ideal platform to investigate correlated excitonic insulators. On the basis of electron-hole bilayers made of MoSe2/hexagonal boron nitride/WSe2 heterostructures, here we study the behaviour of excitonic insulators in a perpendicular magnetic field. We report the observation of excitonic quantum oscillations in both Coulomb drag signals and electrical resistance at low to medium magnetic fields. Under a strong magnetic field, we identify multiple quantum phase transitions between the excitonic insulator phase and the bilayer quantum Hall insulator phase. These findings underscore the interplay between the electron-hole interactions and Landau-level quantization, and enable further exploration of quantum phenomena in composite bosonic insulators.
Quantum fluids and solids, Quantum Hall, Two-dimensional materials
Flexible fibre-shaped fuel cells with gel-mediated internal pressure encapsulation
Original Paper | Fuel cells | 2025-08-24 20:00 EDT
Yongjiang Yuan, Ziyang Liu, Xiuyang Zou, Pengda Fang, Jiale Zhang, Qiuhuan Zhang, Hao Zhang, Qikun Yu, Tao Zhou, Weizheng Li, Sijie Zheng, Mingchen Yang, Zhe Sun, Meifang Zhu, Feng Yan
The development of flexible fuel cells has been hindered by the rigid components and stringent requirements for pressure encapsulation and fuel sealing. Here we report an adaptive internal pressure encapsulation strategy that leverages the dynamic swelling behaviour of woven cotton fibres enclosed in a gel matrix in methanol. This strategy achieves simultaneous interfacial self-reinforcement and pressure modulation, enabling the fabrication of fibre-shaped direct methanol fuel cells. These flexible fuel cells operate across a broad temperature range, from -22 °C to 70 °C, showcasing cuttability, water resistance and fast refuelling capabilities, with full refuelling being achieved within 1 min. Furthermore, the fuel cells maintain consistent discharge performance, even after enduring 2,000 continuous flexing cycles. With an energy density of 161.36 Wh kg-1, these fibre-shaped direct methanol fuel cells surpass the energy densities of typical fibre-based power systems. This technology mitigates many of the technical challenges related to the lightweight and flexible application of fuel cells or fuel cell stacks for powering high-energy flexible devices.
Fuel cells, Gels and hydrogels
Nature Physics
The actin cortex acts as a mechanical memory of morphology in confined migrating cells
Original Paper | Biophysics | 2025-08-24 20:00 EDT
Yohalie Kalukula, Marine Luciano, Gleb Simanov, Guillaume Charras, David B. Brückner, Sylvain Gabriele
Cell migration in narrow microenvironments occurs in numerous physiological processes. It involves successive cycles of confinement and release that drive important morphological changes. However, it remains unclear whether migrating cells can retain a memory of their past morphological states that could potentially facilitate their navigation through confined spaces. We demonstrate that local geometry governs a switch between two cell morphologies, thereby facilitating cell passage through long and narrow gaps. We combined cell migration assays on standardized microsystems with biophysical modelling and biochemical perturbations to show that migrating cells have a long-term memory of past confinement events. The morphological cell states correlate across transitions through actin cortex remodelling. These findings indicate that mechanical memory in migrating cells plays an active role in their migratory potential in confined environments.
Biophysics, Cellular motility
arXiv
Sedimenting rigid particles of certain shapes approach a stationary orientation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-25 20:00 EDT
Chandra Shekhar, Harish Mirajkar, Piotr Zdybel, Yevgen Melikhov, Maria L. Ekiel-Jezewska
This work investigates experimentally and numerically the dynamics of rigid particles settling under gravity in a highly viscous fluid. We demonstrate that certain shapes: cones, crescent moons, arrowheads, and open flat rings reorient and approach a stationary configuration. We determine the mobility coefficients and the characteristic reorientation times. We find out that the two rotational-translational mobility coefficients have opposite signs. Therefore, based on the equations of motion for rigid bodies with two orthogonal planes of symmetry, theoretically derived by Joshi and Govindarajan, Phys. Rev. Lett., 134, 2025, 014002 and Ekiel-Jezewska and Wajnryb, J. Phys. Condens. Matter, 21, 2009, 204102, we conclude that the approached stationary configurations are stable. Owing to the similarity principle, our experimental findings apply to micro-objects in water-based solutions. The reorientation of sedimenting rigid particles of certain shapes to a stationary stable configuration in a relatively short time might be used for biological, medical, or industrial applications.
Soft Condensed Matter (cond-mat.soft)
Non-equilibrium evaporation of Lennard-Jones fluids: Enskog-Vlasov theory and Hertz-Knudsen model
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-25 20:00 EDT
Shaokang Li, Livio Gibelli, Yonghao Zhang
Enskog-Vlasov equation is currently the most sophisticated kinetic model for describing non-equilibrium evaporative flows. While it enables more efficient simulations than the molecular dynamics (MD) methods, its accuracy in reproducing the flow properties of real fluids is limited by the underlying assumptions of the Vlasov forcing term. To address this limitation, this work proposes a molecular kinetic model specifically designed for real fluids, with the Lennard-Jones fluids as an example. The model is first applied to evaluate the equilibrium characteristics of a liquid-vapour system, including the liquid-vapour coexistence curve, vapour pressure, and surface tension coefficient. The results show excellent agreement with the MD simulation and experimental data. Furthermore, the model is used to investigate non-equilibrium evaporation, with a particular focus on the velocity distribution function adjacent to the liquid-vapour interface. The findings reveal significant deviations from the Maxwellian distribution in the vapour region, suggesting that the classical Hertz-Knudsen relation becomes inaccurate when non-equilibrium effects are pronounced. Therefore, this work represents a critical step towards the development of an accurate and efficient computational framework for modelling non-equilibrium liquid-vapour flows for real fluids, with direct relevance to practical applications such as flow cooling.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Wiener Hopf Analysis of Transient Mode-I/Mode-II Fracture in Rotating Heterogeneous Magnetoelastic Orthotropic Media under Initial Stresses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Diksha, Soniya Chaudhary, Pawan Kumar Sharma
This study investigates the fracture behavior under both opening (Mode I) and in-plane sliding (Mode II) conditions for a semi-infinite crack in a rotating, spatially graded magnetoelastic orthotropic strip with combined horizontal and vertical initial normal stresses. The strip is assumed infinite in extent, with the crack aligned along its longitudinal axis and parallel to the rotation axis. The governing field equations are reduced to an analytically tractable form by employing the Fourier transform in the spatial domain and the Laplace transform in the temporal domain. The effect of a sudden application of traction, represented by a Heaviside step function, is analyzed for both normal and shear loading conditions. The resulting boundary-value problem is addressed through the Wiener Hopf method, yielding analytical representations of the stress intensity factors (SIFs). The near tip asymptotic stress fields are evaluated to derive explicit SIF representations for each loading configuration. Laplace inversion is performed using the generalized Chebyshev Laguerre polynomial method. Numerical simulations are conducted for Uranium and Graphite–Epoxy, with isotropic materials considered for comparison to assess the role of anisotropy. The temporal evolution of the SIFs is investigated for varying material gradation parameters, rotation rates, magnetoelastic coupling, and initial stresses. Results reveal that functional grading significantly influences both the magnitude and time evolution of the SIFs, rotation introduces a stabilizing effect, and magnetoelasticity exhibits mode-dependent impacts. These findings provide valuable insight into fracture behavior in advanced magnetoelastic composites, with relevance to high-performance rotating structures such as surface acoustic wave devices, aircraft wings, and helicopter blades.
Materials Science (cond-mat.mtrl-sci)
Entanglement entropy as a probe of topological phase transitions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Manish Kumar, Bharadwaj Vedula, Suhas Gangadharaiah, Auditya Sharma
Entanglement entropy (EE) provides a powerful probe of quantum phases, yet its role in identifying topological transitions in disordered systems remains underexplored. We introduce an exact EE-based framework that captures topological phase transitions even in the presence of disorder. Specifically, for a class of Su-Schrieffer-Heeger (SSH) model variants, we show that the difference in EE between half-filled and near-half-filled ground states, $ \Delta S^{\mathcal{A}}$ , vanishes in the topological phase but remains finite in the trivial phase – a direct consequence of edge-state localization. This behavior persists even in the presence of quasiperiodic or binary disorder. Exact phase boundaries, derived from Lyapunov exponents via transfer matrices, agree closely with numerical results from $ \Delta S^{\mathcal{A}}$ and the topological invariant $ \mathcal{Q}$ , with instances where $ \Delta S^{\mathcal{A}}$ outperforms $ \mathcal{Q}$ . Our results highlight EE as a robust diagnostic tool and a potential bridge between quantum information and condensed matter approaches to topological matter.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
12 pages, 3+3 Figures
Superconductivity and Ferroelectric Orbital Magnetism in Semimetallic Rhombohedral Hexalayer Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Jinghao Deng, Jiabin Xie, Hongyuan Li, Takashi Taniguchi, Kenji Watanabe, Jie Shan, Kin Fai Mak, Xiaomeng Liu
Rhombohedral multilayer graphene has emerged as a promising platform for exploring correlated and topological quantum phases, enabled by its Berry-curvature-bearing flat bands. While prior work has focused on separated conduction and valence bands, we probe the extensive semimetallic regime of rhombohedral hexalayer graphene. We survey a rich phase diagram dominated by flavor-symmetry breaking and reveal an electric-field-driven band inversion through fermiology. Near this inversion, we find a superconducting-like state confined to a region with emergent electron and hole Fermi surfaces. In addition, two multiferroic orbital-magnetic phases are observed: a ferrovalley state near zero field and a ferroelectric state at large fields around charge neutrality. The latter shows electric-field-reversible magnetic hysteresis, consistent with a $ \Delta P \cdot M$ multiferroic order parameter. Our fermiology analysis elucidates the correlated semimetal regime in rhombohedral graphene and underscores its potential to host diverse quantum phases.
Strongly Correlated Electrons (cond-mat.str-el)
Modeling Energy- and Momentum-dependent Scattering Relaxation Times in a Semi-Classical Model of Charge Transport using the Self-Scattering Technique
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
H. A. McDonough, Nicholas A. Mecholsky
Improvement of numerical methods for calculating charge transport quantities of materials from the Boltzmann transport equation (BTE) is important for prediction of material properties. In particular, techniques which allow for more accurate models of scattering rates and band structures while remaining less computationally involved are valuable. The self-scattering technique is one such technique for implementing energy- and momentum-dependent scattering relaxation times in Monte Carlo simulations of charge transport or iterative techniques for solving the BTE. While the technique initially uses a constant relaxation time in the simulation algorithm, we found, upon analysis of the technique, that the energy and momentum total scattering relaxation time may be recovered. To show this, we preformed self-scattering Monte Carlo simulations of electron transport for both energy-dependent and independent relaxation times. The relaxation times and the fraction of scattering type selected in the simulation matched the full rates implemented in the simulation. In order to understand these results, we developed the theory behind the technique, demonstrating that the probability distribution function of free-flight times created using the self-scattering algorithm produces the analytical probability distribution function expression generated by full energy, momentum and time dependent relaxation times and probabilities. However, certain forms of relaxation times may cause the simulation to fail, depending on implementation. Clarity about such techniques is important for improvement of charge transport simulation models and implementation of ab initio scattering rates and band structures.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
32 pages, 12 figures
Interpretability of linear regression models of glassy dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
Anand Sharma, Chen Liu, Misaki Ozawa, Daniele Coslovich
Data-driven models can accurately describe and predict the dynamical properties of glass-forming liquids from structural data. Accurate predictions, however, do not guarantee an understanding of the underlying physical phenomena and the key factors that control them. In this paper, we illustrate the merits and limitations of linear regression models of glassy dynamics built on high-dimensional structural descriptors. By analyzing data for a two-dimensional glass model, we show that several descriptors commonly used in glass-transition studies display multicollinearity, which hinders the interpretability of linear models. Ridge regression suppresses some of the shortcomings of multicollinearity, but its solutions are not succinct enough to be physically interpretable. Only by using dimensional reduction techniques we eventually obtain linear models that strike a balance between prediction accuracy and interpretability. Our analysis points to a key role of local packing and composition fluctuations in the glass model under study.
Statistical Mechanics (cond-mat.stat-mech), Materials Science (cond-mat.mtrl-sci)
22 pages, 16 figures
Hybrid Monte Carlo Metadynamics (hybridMC-MetaD)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Charlotte Shiqi Zhao, Sun-Ting Tsai, Sharon C. Glotzer
We propose the powerful integration of the Hybrid Monte Carlo (hybridMC) algorithm and Well-Tempered Metadynamics. This new algorithm, hybridMC-MetaD, enhances the flexibility and applicability of metadynamics by allowing for the utilization of a wider range of collective variables (CVs), namely non-differentiable CVs. We demonstrate the usage of hybridMC-MetaD through five examples of rare events in molecular dynamics (MD) simulations, including a rare transition in a model potential system, condensation of the argon system, crystallization in a nearly-hard sphere system, a nearly-hard bipyramid system and a colloidal suspension. By taking advantage of hybridMC, which combines molecular dynamics (MD) and MC, we are able to bias the transitions along non-differentiable CVs for all five cases, which would be unfeasible with conventional MD simulations. Enabled by metadynamics, we observed significant acceleration of the phase transitions and calculated free energy barriers using the hybridMC-MetaD simulation data. For the nearly-hard bipyramid system whose crystallization is primarily driven by entropy, we report the free energy surface for the first time. Through our case studies, we show that our hybridMC-MetaD scheme reduces the complexity of using metadynamics and increases its accessibility. We believe the hybridMC-MetaD algorithm will stimulate greater interest in, and foster broader applications of metadynamics.
Materials Science (cond-mat.mtrl-sci)
Dual Topology as a Fingerprint of Relativistic Altermagnetism in AgF$_2$ Monolayer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
J. W. González, R. A. Gallardo, N. Vidal-Silva, A. M. León
Altermagnets have emerged as a fertile ground for quantum phenomena, but topological phases unifying different quasiparticles remain largely unexplored. Here, we demonstrate that monolayer AgF$ _2$ hosts a dual topological state, driven by a single ferroelastic distortion. This polar transition breaks inversion symmetry and unleashes relativistic spin-orbit effects, simultaneously imparting non-trivial topology to electrons and magnons. The result is valence bands with opposite Chern numbers, $ C^E=\pm3$ , and a magnon spectrum with a full topological gap and chiral bands, $ C^M=\pm1$ . This work realizes topological altermagnonics in a tangible material platform, with a clear experimental fingerprint in the transverse thermal Hall effect. The coexistence of fermionic and bosonic topology in AgF$ _2$ opens new directions for designing intrinsically hybrid quantum matter.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
High temporal stability of niobium superconducting resonators by surface passivation with organophosphonate self-assembled monolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Harsh Gupta, Rui Pereira, Leon Koch, Niklas Bruckmoser, Moritz Singer, Benedikt Schoof, Manuel Kompatscher, Stefan Filipp, Marc Tornow
One main limiting factor towards achieving high coherence times in superconducting circuits is two level system (TLS) losses. Mitigating such losses requires controlling the formation of native oxides at the metal-air interface. Here, we report the growth of alkyl-phosphonate self-assembled monolayers (SAMs) on Nb thin films following oxide removal. The impact of passivation was evaluated via the performance of coplanar waveguide resonators at 10mK, in terms of quality factor and resonant frequency, over six days of air exposure. Un-passivated resonators exhibited an ~80% increase in loss at single-photon power levels, whereas SAM-passivated resonators maintained excellent temporal stability, attributed to suppressed oxide regrowth. By employing a two-component TLS model, we discern distinct prominent loss channels for each resonator type and quantified the characteristic TLS loss of the SAMs to be ~5x10^-7. We anticipate our passivation methodology to offer a promising route toward industrial-scale qubit fabrication, particularly where long-term device stability is critical.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
35 pages, 21 figures, Harsh Gupta and Marc Tornow are the corresponding authors
Unconventional superconductivity induced by rare-earth substitution in Nd1-xEuxNiO2 thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-25 20:00 EDT
Dung Vu, Hangoo Lee, Daniele Nicoletti, Wenzheng Wei, Zheting Jin, Dmitry V. Chichinadze, Michele Buzzi, Yu He, Christopher A. Mizzi, Tiema Qian, Boris Maiorov, Alexey Suslov, Cyprian Lewandowski, Sohrab Ismail-Beigi, Frederick Walker, Andrea Cavalleri, Charles Ahn
High temperature superconductivity is typically associated with strong coupling and a large superconducting gap, yet these characteristics have not been demonstrated in the nickelates. Here, we provide experimental evidence that Eu substitution in the spacer layer of Nd1-xEuxNiO2 (NENO) thin films enhances the superconducting gap, driving the system toward a strong-coupling regime. This is accompanied by a magnetic-exchange-driven magnetic-field-enhanced superconductivity. We investigate the upper critical magnetic field, Hc2, and superconducting gap of superconducting NENO thin films with x=0.2 to 0.35. Magnetoresistance measurements reveal magnetic-field-enhanced superconductivity in NENO films. We interpret this phenomenon as a result of interaction between magnetic Eu ions and superconducting states in the Ni dx2-y2 orbital. The upper critical magnetic field strongly violates the weak-coupling Pauli limit. Infrared spectroscopy confirms a large gap-to-Tc ratio $ 2 \Delta k_B T_c \approx 5 - 6$ , indicating a stronger coupling pairing mechanism in NENO relative to the Sr-doped NdNiO2. The substitution of Eu in the rare-earth layer provides a method to modify the superconducting gap in Nd-based nickelates, an essential factor in engineering high-Tc superconductivity in infinite-layer nickelates.
Superconductivity (cond-mat.supr-con)
Under Review
A simulation-based training framework for machine-learning applications in ARPES
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
MengXing Na, Chris Zhou, Sydney K. Y. Dufresne, Matteo Michiardi, Andrea Damascelli
In recent years, angle-resolved photoemission spectroscopy (ARPES) has advanced significantly in its ability to probe more observables and simultaneously generate multi-dimensional datasets. These advances present new challenges in data acquisition, processing, and analysis. Machine learning (ML) models can drastically reduce the workload of experimentalists; however, the lack of training data for ML – and in particular deep learning – is a significant obstacle. In this work, we introduce an open-source synthetic ARPES spectra simulator - aurelia - for the purpose of generating the large datasets necessary to train ML models. As a demonstration, we train a convolutional neural network to evaluate ARPES spectra quality – a critical task performed during the initial sample alignment phase of the experiment. We benchmark the simulation-trained model against actual experimental data and find that it can assess the spectra quality more accurately than human analysis, and swiftly identify the optimal measurement region with high precision. Thus, we establish that simulated ARPES spectra can be an effective proxy for experimental spectra in training ML models.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
9 pages, 6 figures
Universal Fluctuations in the Tail Probability for d=2 Random Walks in Space-Time Random Environments
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
Franscesca Ark, Jacob B. Hass, Eric I. Corwin
Many diffusive systems involve correlated random walkers due to a shared environment. Such systems can be modeled as random walks in random environments (RWRE). These models differ from classical diffusion in the behavior of the extremes – the walkers that move the fastest or farthest. In spatial dimension $ d=1$ RWRE models have been well studied numerically and analytically and exhibit universal behavior in the Kardar-Parisi-Zhang universality class. Here, we study discrete lattice RWRE models in $ d=2$ . We find that the tail probability exhibits a different universal scaling form, which is nevertheless characterized by the same coefficient, $ \lambda_\mathrm{ext}$ , as in the $ d=1$ case. We observe a critical scaling regime for fluctuations in the tail probability at positions that scale linearly in time.
Statistical Mechanics (cond-mat.stat-mech)
6 pages, 4 figures
Strong Correlation Driven Quadrupolar to Dipolar Exciton Transitions in a Trilayer Moiré Superlattice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
Yuze Meng, Lei Ma, Li Yan, Ahmed Khalifa, Dongxue Chen, Shuai Zhang, Rounak Banerjee, Takashi Taniguchi, Kenji Watanabe, Seth Ariel Tongay, Benjamin Hunt, Shi-Zeng Lin, Wang Yao, Yong-Tao Cui, Shubhayu Chatterjee, Su-Fei Shi
The additional layer degree of freedom in trilayer moiré superlattices of transition metal dichalcogenides enables the emergence of novel excitonic species, such as quadrupolar excitons, which exhibit unique excitonic interactions and hold promise for realizing intriguing excitonic phases and their quantum phase transitions. Concurrently, the presence of strong electronic correlations in moiré superlattices, as exemplified by the observations of Mott insulators and generalized Wigner crystals, offers a direct route to manipulate these new excitonic states and resulting collective excitonic phases. Here, we demonstrate that strong exciton-exciton and electron-exciton interactions, both stemming from robust electron correlations, can be harnessed to controllably drive transitions between quadrupolar and dipolar excitons. This is achieved by tuning either the exciton density or electrostatic doping in a trilayer semiconducting moiré superlattice. Our findings not only advance the fundamental understanding of quadrupolar excitons but also usher in new avenues for exploring and engineering many-body quantum phenomena through novel correlated excitons in semiconducting moiré systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nature Photonics (2025)
FIRE-GNN: Force-informed, Relaxed Equivariance Graph Neural Network for Rapid and Accurate Prediction of Surface Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Circe Hsu, Claire Schlesinger, Karan Mudaliar, Jordan Leung, Robin Walters, Peter Schindler
The work function and cleavage energy of a surface are critical properties that determine the viability of materials in electronic emission applications, semiconductor devices, and heterogeneous catalysis. While first principles calculations are accurate in predicting these properties, their computational expense combined with the vast search space of surfaces make a comprehensive screening approach with density functional theory (DFT) infeasible. Here, we introduce FIRE-GNN (Force-Informed, Relaxed Equivariance Graph Neural Network), which integrates surface-normal symmetry breaking and machine learning interatomic potential (MLIP)-derived force information, achieving a twofold reduction in mean absolute error (down to 0.065 eV) over the previous state-of-the-art for work function prediction. We additionally benchmark recent invariant and equivariant architectures, analyze the impact of symmetry breaking, and evaluate out-of-distribution generalization, demonstrating that FIRE-GNN consistently outperforms competing models for work function predictions. This model enables accurate and rapid predictions of the work function and cleavage energy across a vast chemical space and facilitates the discovery of materials with tuned surface properties
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
Enhanced thermopower in a magnetic semiconductor EuTe4 with multiple charge-density-wave instabilities/
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Hidefumi Takahashi, Kiichiro Yoshida, Akitoshi Nakano, Shintaro Ishiwata
We investigate the layered magnetic semiconductor EuTe4, focusing on its intricate charge-density wave (CDW) states near and above room temperature through single-crystal X-ray diffraction (XRD), magnetic, and thermoelectric this http URL XRD measurement revealed that the CDW state inducing the polar lattice distortion persists even at 650 K, demonstrating its remarkable thermal stability. Notably, the Seebeck coefficient near room temperature reaches values exceeding 500 uVK-1. This large Seebeck coefficient, not fully captured by a simple band calculation, is comparable to those observed in heavy-electron semiconducting oxides, suggesting the importance of electron correlation and spin/lattice instabilities. Furthermore, potentially reflecting the competition of two types of CDW states, the thermal conductivity near room temperature is as low as 0.02 Wcm-1K-1. As a result, the thermoelectric figure of merit zT reaches 0.22 at 460 K. These findings establish EuTe4 as a compelling platform to explore novel types of thermoelectric materials with multiple electronic instability.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 4 figures
Physical Review X Energy 4, 033009 (2025)
Evolution of magnetic bubble domains in the uniaxial ferromagnet CeRu$_2$Ga$_2$B inferred from the Hall effect and ac magnetic susceptibility
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Peter E. Siegfried, Mark Maus, Alexander C. Bornstein, Dirk Wulferding, JeehoonKim, Ryan E. Baumbach, Eric D. Bauer, Filip Ronning, and Minhyea Lee
We study the Hall effect, AC magnetic susceptibility ($ \chi_{\rm ac}$ ), and magnetic force microscopy of the uniaxial ferromagnet CeRu$ _2$ Ga$ 2$ B with a centrosymmetric crystal structure. We observe a finite topological Hall effect (THE) within the ordered phase before the magnetization is polarized by applied field. By comparing the field dependences of the area fraction of the magnetic bubbles, the derivative of $ \chi{\rm ac}$ , and the THE signal, we deduce that the magnetic bubbles of CeRu$ _2$ Ga$ _2$ B evolve from the trivial to topological spin texture with field. Our findings will be utilized to expand the search for magnetic materials hosting the topological spin textures to ones with uniaxial anisotropy, and open a new possibility to tailor the topological spin texture.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 6 figures
Controlling resonant spin photocurrent using magnetic field; application to a magnetoelectric oxide Cr2O3
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
Zhuo-Cheng Gu, Hiroaki Ishizuka
We study the magnon spin photocurrent in effective spin models for Cr2O3, a material known for its magnetoelectric effect. Using nonlinear response theory, we show that magnon spin current can be generated by both linearly and circularly polarized electromagnetic waves via one-magnon processes. While linearly polarized waves induce a spin current even in the absence of a static magnetic field, circularly polarized waves lead to a spin current only when a static field is present, and the current reverses its direction upon field inversion. The distinct dependence on the external magnetic field and the contrasting responses to different polarizations allow the spin photocurrent to be differentiated from competing effects such as spin pumping or inhomogeneous heating, facilitating experimental verification. These results suggest that Cr2O3 is a promising candidate for experimental studies of magnon photocurrent.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Noisy active matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-25 20:00 EDT
Atanu Chatterjee, Tuhin Chakrabortty, Saad Bhamla
Noise threads every scale of the natural world. Once dismissed as mere background hiss, it is now recognized as both a currency of information and a source of order in systems driven far from equilibrium. From nanometer-scale motor proteins to meter-scale bird flocks, active collectives harness noise to break symmetry, explore decision landscapes, and poise themselves at the cusp where sensitivity and robustness coexist. We review the physics that underpins this paradox: how energy-consuming feedback rectifies stochastic fluctuations, how multiplicative noise seeds patterns and state transitions, and how living ensembles average the residual errors. Bridging single-molecule calorimetry, critical flocking, and robophysical swarms, we propose a unified view in which noise is not background blur but a tunable resource for adaptation and emergent order in biology and engineered active matter.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
Ball milling enables phase-pure synthesis of a temperature sensitive ternary chloride, MgZrCl$_6$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Christopher L. Rom, Austin Shotwell, Sinclair Combs, Autumn Peters, Lauren Borgia, James R. Neilson, Annalise E. Maughan
Ball milling is a powerful synthetic tool for discovering new inorganic materials. Inspired by the high ionic conductivity in Li$ _2$ ZrCl$ _6$ synthesized via mechanochemistry, we synthesized MgZrCl$ _6$ with a similar method. High resolution synchrotron X-ray diffraction shows that MgZrCl$ _6$ is poorly crystalline after ball milling, but crystallizes in a layered hexagonal structure ($ P31c$ ) after heat treatment. In situ synchrotron X-ray diffraction reveals a narrow temperature window around 400 °C in which crystallization occurs. At higher temperatures the phase decomposes. Pair distribution function analysis shows 2D sheets of MgZrCl$ _6$ form after milling, with heating driving 3D crystallization. Raman spectroscopy also shows evidence of MgZrCl$ _6$ after milling. Electrochemical impedance spectroscopy does not reveal ionic conductivity in MgZrCl$ _6$ (limit of detection ca. $ 1.4 \times 10^{-8}$ S/cm). In addition to supporting existing design rules for Mg-based solid electrolytes, this work shows the power of ball milling to synthesize temperature-sensitive inorganic compounds with high yield.
Materials Science (cond-mat.mtrl-sci)
Intrinsic Strain-Driven Topological Evolution in SrRuO3 via Flexural Strain Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Liguang Gong, Hongping Jiang, Bin Lao, Xuan Zheng, Xuejiao Chen, Zhicheng Zhong, Yan Sun, Xianfeng Hao, Milan Radovic, Run-Wei Li, Zhiming Wang
Strain engineering offers a powerful route to tailor topological electronic structures in correlated oxides, yet conventional epitaxial strain approaches introduce extrinsic factors such as substrate-induced phase transitions and crystalline quality variations, which makes the unambiguous identification of the intrinsic strain effects challenging. Here, we develop a flexural strain platform based on van der Waals epitaxy and flexible micro-fabrication, enabling precise isolation and quantification of intrinsic strain effects on topological electronic structures in correlated oxides without extrinsic interference. Through strain-dependent transport measurements of the Weyl semimetal SrRuO3, we observed a significant enhancement of anomalous Hall conductivity by 21% under a tiny strain level of 0.2%, while longitudinal resistivity remains almost constant – a hallmark of intrinsic topological response. First-principles calculations reveal a distinct mechanism where strain-driven non-monotonic evolution of Weyl nodes across the Fermi level, exclusively governed by lattice constant modulation, drives the striking AHC behavior. Our work not only highlights the pivotal role of pure lattice strain in topological regulation but also establishes a universal platform for designing flexible topological oxide devices with tailored functionalities.
Materials Science (cond-mat.mtrl-sci)
19 pages, 4 figures
Thermomodulated intrinsic Josephson effect in Kagome CsV3Sb5
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-25 20:00 EDT
Tian Le, Zhuokai Xu, Jinjin Liu, Ruiya Zhan, Zhiwei Wang, Xiao Lin
Superconducting chiral domains associated with a time-reversal symmetry-breaking order parameter have garnered significant attention in Kagome systems. In this work, we demonstrate both the intrinsic direct-current and alternating-current Josephson effects in the nanoplates of the vanadium-based Kagome material CsV3Sb5, as evidenced by Fraunhofer-like patterns and Shapiro steps. Moreover, both the Fraunhofer-like patterns and Shapiro steps are modulated by thermal cycling, suggesting that the Josephson effects arise from dynamic superconducting domains. These findings may provide new insights into chiral superconductivity in CsV3Sb5 and highlight the potential of these intrinsic Josephson junctions for applications in chiral superconductor based quantum devices.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 5 figures, Physical Review Letter in press
Quantum droplets in one-dimensional mixtures of quasi Bose-Einstein condensates and Tonks-Girardeau gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-25 20:00 EDT
Wen-Bin He, Su Yi, Thomas Busch
While binary atomic Bose-Einstein condensates are typically prone to collapse under strong interspecies attraction, it has been shown that higher-order fluctuation corrections, known as Lee-Huang-Yang corrections, can stabilize the mixture. In this work, we demonstrate an alternative stabilization mechanism based on kinetic energy. Specifically, we consider a one-dimensional mixture of a quasi-BEC and a Tonks-Girardeau gas, and show that the kinetic energy of the TG component can counteract the interspecies attraction, thereby preventing collapse. This balance leads to the formation of a self-bound quantum droplet, which exhibits two distinct regimes: a low-density and a high-density droplet. We argue that these regimes are smoothly connected by a crossover. Furthermore, an analysis of the derivatives of the ground state energy reveals that the transition from a miscible mixture to the droplet phase is of third order. Our findings extend the theoretical understanding of quantum droplets in low-dimensional quantum gases, and the proposed system is experimentally accessible within current ultracold atom platforms.
Quantum Gases (cond-mat.quant-gas)
10 pages, 6 figures
Power-law correction in the probability density function of the critical Ising magnetization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
Federico Camia, Omar El Dakkak, Giovanni Peccati
At the critical point, the probability density function of the Ising magnetization is believed to decay like $ \exp{(-x^{\delta+1})}$ , where $ \delta$ is the Ising critical exponent that controls the decay to zero of the magnetization in a vanishing external field. In this paper, we discuss the presence of a power-law correction $ x^{\frac{\delta-1}{2}}$ , which has been debated in the physics literature. We argue that whether such a correction is present or not is related to the asymptotic behavior of a function that measures the extent to which the average magnetization of a finite system with an external field is influenced by the boundary conditions. Our discussion is informed by a mixture of heuristic calculations and rigorous results. Along the way, we review some recent results on the critical Ising model and prove properties of the average magnetization in two dimensions which are of independent interest.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Probability (math.PR)
18 pages, invited paper to appear in MPAG special issue “The Ising model at 100: some modern perspectives”
Terahertz third-harmonic generation of lightwave driven Weyl fermions far from equilibrium
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Patrick Pilch, Changqing Zhu, Sergey Kovalev, Renato M. A. Dantas, Amilcar Bedoya-Pinto, Stuart S. P. Parkin, Zhe Wang
We report on time-resolved ultrafast terahertz third-harmonic generation spectroscopy of nonequilibrium dynamics of Weyl fermions in a nanometer thin film of the Weyl semimetal TaP. Under a strong multicycle narrowband terahertz drive, very efficient terahertz third-harmonic generation is observed at room temperature which exhibits a perturbative cubic power-law dependence on the terahertz drive. By varying the polarization of the drive pulse from linear to elliptical, we realize a sensitive tuning of the third harmonic yield. We ascribe the observed strong nonlinearity to THz field driven nonlinear kinetics of the Weyl fermions.
Strongly Correlated Electrons (cond-mat.str-el)
On the nature and charge state of the X-Defect, a radiation-induced Silicon defect with field-enhanced charge carrier emission
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Niels Sorgenfrei, Yana Gurimskaya, Anja Himmerlich, Michael Moll, Ulrich Parzefall, Ioana Pintilie, Joern Schwandt
The elusive X-Defect, a defect found in low-resistivity $ p$ -type Silicon after irradiation, observed as a low-temperature shoulder of the $ \mathrm{B}\mathrm{i}\mathrm{O}\mathrm{i}$ defect (Boron-interstitial-Oxygen-interstitial complex) in Thermally Stimulated Current (TSC) measurements, was investigated to determine its properties, matching them with those of a previously identified defect. Through a combination of TSC, Deep-Level Transient Spectroscopy (DLTS), Difference-DLTS (DDLTS), numerical simulations of field-enhanced charge carrier emissions in TSC measurements and a comparison to literature, the X-Defect was identified as the singly positively charged Silicon di-vacancy $ \mathrm{V}_2(+/0)$ . This assignment is supported by an agreement in activation energy, capture cross-section, trap type and charge emission process, as well as simulations comparing the effects of phonon-assisted tunnelling (PAT) and Poole-Frenkel (PF) mechanisms on TSC spectra. DDTLS measurements revealed a quadratic dependence of the activation energy on the electric field strength, confirming PAT as the prevailing mechanism over PF in the case of the radiation-induced X-Defect. Assigning the X-Defect to an electrically neutral defect in the space charge region resolves previous contradictions regarding its deficiency in impacting on the effective doping concentration.
Materials Science (cond-mat.mtrl-sci), High Energy Physics - Experiment (hep-ex), Instrumentation and Detectors (physics.ins-det)
11 pages, 13 figures, 1 table, Submitted to NIM-A
Do 1-dimensional metals prefer to form even-numbered van der Waals clusters ?
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Parallel quasi-one-dimensional metals are known to experience strong dispersion (van der Waals, vdW) interactions that fall off unusually slowly with separation between the metals. Examples include nanotube brushes, nano-wire arrays, and also common biological structures. In a many-stranded bundle, there are potentially strong multi-strand vdW interactions that go beyond a simple sum of negative (attractive) pairwise inter-strand energies. Perturbative analysis showed that these contributions alternate in sign, with the odd (triplet, quintuplet, …) terms being positive (repulsive). The triplet case leds to the intriguing speculation that these strands may prefer to coalesce into even-numbered bundles, which could have implications for the formation kinetics of DNA, for example. Here we use a non-perturbative vdW energy analysis to show that this conjecture is not true in general. As our counter-example we consider 6 strands and show that 2 well-separated bundles of 3 strands have a more negative total vdW energy than 3 well-separated bundles of 2 strands ( i.e. an odd-number preference). We also discuss a bundle of 6 strands and explore the relative contributions beyond pairwise interactions.
Materials Science (cond-mat.mtrl-sci)
17 pages, 5 figures
Investigating structure and physical properties of quaternary layered transition metal oxide Na2Cu2TeO6
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
We investigated the crystal structure, magnetic behavior, and optical properties of the layered honeycomb compound Na2Cu2TeO6. X-ray and neutron diffraction confirmed a monoclinic structure, with Cu ions arranged in dimerized chains. Magnetic susceptibility measurements yielded a Curie-Weiss temperature significantly lower than the expected spin-only value, indicating the presence of strong antiferromagnetic interactions and enhanced quantum fluctuations. A broad maximum near 160 K in the susceptibility data is consistent with short-range one-dimensional antiferromagnetic correlations. Magnetization measurements showed negligible coercivity, and specific heat data revealed no anomalies down to 3 K. Temperature-dependent neutron diffraction showed no evidence of long-range magnetic order. Optical absorption studies using UV-Visible spectroscopy displayed a sharp absorption edge in the UV region. Tauc analysis estimated a direct optical band gap of approximately 2.10 eV, with no clear indication of an indirect transition. These observations provide insight into the interplay between structural distortions, low-dimensional magnetism, and optical behavior in Na2Cu2TeO6
Strongly Correlated Electrons (cond-mat.str-el)
Ultrafast Laser-Induced Magnetic Relaxation in Artificial Spin Ice Driven by Dipolar Interactions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
D. Pecchio, S. Sahoo, O. Chubykalo-Fesenko, S. Koraltan, G. M. Macauley, T. Thomson, D. Suess, V. Scagnoli, L. J. Heyderman
It is of great interest to develop methods to rapidly and effectively control the magnetic configurations in artificial spin ices, which are arrangements of dipolar coupled nanomagnets that have a variety of fascinating collective magnetic phenomena associated with them. This is not only valuable in terms of acquiring fundamental understanding but is also important for future high-performance applications. Here, we demonstrate ultrafast control of magnetic relaxation in square artificial spin ice through femtosecond laser pulsed excitation, enabling rapid access to low-energy states via dipolar interactions. Time-resolved magneto-optical Kerr effect measurements reveal that, after laser-induced demagnetization, the magnetization recovers within picoseconds. During this brief transient window, dipolar coupling drives a collective magnetic ordering. Ex-situ magnetic force microscopy confirms the emergence of extended Type I vertex domains, characteristic of ground-state ordering, thus establishing ultrafast laser-driven relaxation as a route to attain the low-energy states. Through complementary energy barrier calculations and micromagnetic simulations incorporating Landau-Lifshitz-Bloch dynamics, we elucidate the underlying mechanism: transient ultrafast demagnetization followed by rapid remagnetization that enables a dipolar-driven collective rearrangement. Moreover, a tailored decreasing-fluence laser annealing protocol is shown to enhance ground-state ordering, consistently achieving over 92% ground-state vertex populations. This work opens the way to ultrafast and spatially selective control of magnetic states in artificial spin ice for spin-based computation and memory technologies, and highlights the critical interplay of thermal fluctuations, magnetostatic coupling, and transient magnetization dynamics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dynamic driving enables independent control of material bits for targeted memory
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-25 20:00 EDT
E. Gutierrez-Prieto, C.M. Meulblok, M. van Hecke, P.M. Reis
Mechanical structures made from bistable elements can store configurational memories to enable tunable stiffness, sequential shape-morphing, and computation. While control over configurations is essential, it typically requires local and individual access to all elements. Here, we introduce a dynamic control strategy that enables transitions between any pair of configurations within a single global drive cycle by exploiting sensitivity to different (orders of) derivatives of the driving. We illustrate this approach using bistable beams that snap through based on their collective rotation rate and acceleration. Through rational design and selection of drive cycles, we demonstrate targeted transitions along controllable pathways, including the writing of five-bit memories that encode all alphabetic characters. This form of dynamical control can be generalized to inertial, fluidic, electromagnetic, and electronic systems, thus providing a powerful method for writing memories and enabling smart, remotely controllable devices for applications in microfluidics, implants, smart infrastructure, and underwater or medical robotics.
Soft Condensed Matter (cond-mat.soft)
7 pages, 4 figures in main text, 4 figures in SI
First-principles many-body study for electronic, optical, and excitonic properties of RbTlCl3 perovskite for solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Siddharth, Vinod Kumar Solet, Sudhir K. Pandey
We present a detailed many-body ab initio study of the valence-skipper RbTlCl$ _{3}$ perovskite compound for photovoltaic (PV) applications. The electronic and optical properties, both with and without spin-orbit coupling, have been calculated using density functional theory (DFT) and many-body excited-state calculations. The band gap, which is indirect in nature, is found to be 0.95 eV and 0.89 eV from PBE and PBEsol, respectively. The optical properties have been computed using four different approximations: independent particle approximation (IPA), IPA with scissor correction (IQPA), random phase approximation for local-field effects (LFEs), and the Bethe-Salpeter equation (BSE). The estimated highest value of the imaginary part of the dielectric function using IQPA is 7 at 2 eV, which slightly decreases to 5.7 due to LFEs. Within BSE, the peak value is obtained to be maximum at 1.6 eV with a magnitude of 10.8, which indicates the strong excitonic effect below the optical gap. Large number of bright and dark bound excitons are found, where the binding energies of four main bound bright excitons are found in the range of 299-350 meV. The exciton amplitude in both reciprocal and real space is analyzed. The main bound bright exciton is localized in the reciprocal space, while this exhibits a delocalized nature in real space. The BSE predicts a highest absorption coefficient of 3.6 $ \times$ $ 10^{6}$ cm$ ^{-1}$ at 1.7 eV, while a minimum reflectivity in the active region of the solar energy spectrum is obtained to be around 2.7%. Finally, the solar efficiency has been estimated using the spectroscopic limited maximum efficiency approach and obtained highest value is 15.5% at a thickness of 0.5 $ \mu$ m. These findings reveal a significant excitonic effect in the absorption spectra of RbTlCl$ _{3}$ and highlight its potential as a promising material for single-junction thin-film solar cells.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
9 figures
Magneto-conductivity and CME in Dirac semimetals from Keldysh technique in Landau levels basis
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
Negative magnetoresistance in Dirac semimetals is conventionally considered as a manifestation of chiral magnetic effect (CME), by means of a postulated Chiral Kinetic equation. In this paper we study magnetoconductivity in large Fermi energy Dirac semimetals, in one of which (ZrTe$ _5$ ) the effect was observed for the first time. Starting with a Hamiltonian for a semi-realistic model of such a Dirac semimetal, we apply the Non-equilibrium Diagram Technique (NDT, or the Keldysh technique) to derive the kinetic equations, to investigate the electrons relaxation due to interaction with phonons and disorder, and, finally, to calculate the DC magnetoconductivity (the longitudinal to magnetic field component of conductivity) as a function of magnetic field strength and temperature. Finally, we compare the obtained temperature dependencies with available to us experimental data.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 5 figures
Extreme magnetic field-boosted superconductivity in a high-temperature superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-25 20:00 EDT
Km Rubi, King Yau Yip, Elizabeth Krenkel, Nurul Fitriyah, Xing Gao, Saurav Prakash, S. Lin Er Chow, Tsz Fung Poon, Mun K. Chan, David Graf, A. Ariando, Neil Harrison
Magnetic fields typically suppress superconductivity through Pauli and orbital limiting effects. However, there are rare instances of magnetic-field-induced superconductivity, as seen in Chevrel phase compounds [1], organic conductors [2], uranium-based heavy-fermion systems [3, 4], and moire graphene [5], though these materials possess inherently low superconducting transition temperatures (Tc). Here, we demonstrate high field-stabilized superconductivity in a class of materials with a significantly higher Tc (up to 40 K): the infinite-layer nickelates [6]. Both low-field and high-field superconducting states can be plausibly explained by a compensation mechanism akin to the Jaccarino-Peter effect. These findings demonstrate the possibility of achieving substantially enhanced upper critical fields in high-temperature superconductors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 3 main figures, 5 extended data
Scalable Hybrid quantum Monte Carlo simulation of U(1) gauge field coupled to fermions on GPU
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Kexin Feng, Chuang Chen, Zi Yang Meng
We develop a GPU-accelerated hybrid quantum Monte Carlo (QMC) algorithm to solve the fundamental yet difficult problem of $ U(1)$ gauge field coupled to fermions, which gives rise to a $ U(1)$ Dirac spin liquid state under the description of (2+1)d quantum electrodynamics QED$ 3$ . The algorithm renders a good acceptance rate and, more importantly, nearly linear space-time volume scaling in computational complexity $ O(N{\tau} V_s)$ , where $ N_\tau$ is the imaginary time dimension and $ V_s$ is spatial volume, which is much more efficient than determinant QMC with scaling behavior of $ O(N_\tau V_s^3)$ . Such acceleration is achieved via a collection of technical improvements, including (i) the design of the efficient problem-specific preconditioner, (ii) customized CUDA kernel for matrix-vector multiplication, and (iii) CUDA Graph implementation on the GPU. These advances allow us to simulate the $ U(1)$ Dirac spin liquid state with unprecedentedly large system sizes, which is up to $ N_\tau\times L\times L = 660\times66\times66$ , and reveal its novel properties. With these technical improvements, we see the asymptotic convergence in the scaling dimensions of various fermion bilinear operators and the conserved current operator when approaching the thermodynamic limit. The scaling dimensions find good agreement with field-theoretical expectation, which provides supporting evidence for the conformal nature of the $ U(1)$ Dirac spin liquid state in the \qed. Our technical advancements open an avenue to study the Dirac spin liquid state and its transition towards symmetry-breaking phases at larger system sizes and with less computational burden.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
15+4 pages, 10+7 figures
Observation of negative orbital torque from Vanadium
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
Nikhil Vijayan (1), Durgesh Kumar (1), Ao Du (1), Lei Gao (2), Zijie Xiao (2), Hai I. Wang (2), Rahul Gupta (1), Gerhard Jakob (1), Sachin Krishnia (1), Yuriy Mokrousov (1 and 3), Mathias Kläui (1 and 4) ((1) Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany, (2) Max Planck Institute for Polymer Research, Mainz 55128, Germany, (3) Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany, (4) Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway)
We present systematic investigations of orbital torques generated from the light metal $ V$ , revealing a negative orbital torque. We observe that the damping-like torque (DLT) per unit electric field depends on the choice of the ferromagnetic layer, with approximately seven times higher torque efficiency in $ Ni/V$ as compared to $ Fe_{60}Co_{20}B_{20}/V$ . We find the sign of DLT per unit electric field from $ V$ is opposite to that from $ Pt$ . These results collectively confirm the existence of negative orbital Hall effect (OHE) in $ V$ . Furthermore, the DLT per unit electric field increases with the $ V$ layer thickness, maintaining the negative sign at all thicknesses. We also note that the DLT per unit electric field exceeds that of the $ Pt$ reference samples at higher $ V$ thicknesses. Through fitting using the drift-diffusion equation, we extract a high effective orbital Hall conductivity of $ -(1.46 \pm 0.09),\frac{\hbar}{2e},\times 10^{5},\Omega^{-1},\mathrm{m}^{-1}$ and a long orbital diffusion length of $ (13.7 \pm 0.9),\mathrm{nm}$ in $ V$ . .
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Corresponding author Mathias Kläui Equal contribution from Nikhil Vijayan and Durgesh Kumar
Mechanical Reinforcement of Graphene via Wrinkling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-25 20:00 EDT
Hadi Arjmandi-Tash, Roshan Prasad, Hanqing Liu, Gerard Verbiest, Dominic Vella, Farbod Alijani
Mechanical cantilevers are central to nanotechnology, with ultimate sensitivity achieved at the atomic limit, where low bending rigidity makes stability the fundamental challenge. Here, we introduce a wrinkle-induced stiffening approach that enhances the bending rigidity of monolayer graphene by several orders of magnitude, enabling the fabrication of mechanically robust graphene cantilevers. When suspended over microcavities, these wrinkled membranes exhibit significant increases in both in-plane and out-of-plane stiffness, as confirmed by nanoindentation and resonance measurements, which also reveal that enhanced bending rigidity strongly influences their vibrational response. This behavior marks a transition from tension-dominated mechanics to a regime where bending effects become prominent, even in a single atomic layer. By sculpting these structures, we realize graphene cantilevers with measured bending rigidities between $ 10^6$ and $ 10^7$ eV, while maintaining femtogram-scale mass. These findings open new directions in nanomechanical sensing and cantilever-based technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantifying time in Monte Carlo simulations: application to relaxation processes and AC susceptibilities of magnetic nanoparticles assemblies
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
A. Morjane, J.-G. Malherbe, J.-J. Alonso, F. Vernay, V. Russier
The study of the response of magnetic nanoparticles (MNP) assemblies to an external alternating magnetic field is of great interest for applications such as hyperthermia. The key quantity here is the complex susceptibility and its behavior in terms of temperature and frequency. From a theoretical point of view it can be obtained by Monte Carlo (MC) simulation with the time quantified Monte Carlo (TQMC) method if a physical time is associated with the MC step. Here we revisit this method by showing that the time unit can be derived from the MC stochastic process of the isolated particle. We first obtain a MC unit of time from the relaxation of the system at fixed temperature. Then this unit of time is used to compute complex susceptibilities. We show that it is now possible to match the TQMC results with actual experimental results regarding frequency dependent in phase susceptibilities and quantify the unit of time in seconds. Finally we show that the time unit obtained for the isolated particle remains valid when considering interacting particles such as the Heisenberg coupling or dipole dipole interactions.
Statistical Mechanics (cond-mat.stat-mech)
Deformation mechanisms of L-PBF-processed Ti-6Al-4V investigated using a combined experimental and simulation approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Pushkar Prakash Dhekne, Nikhil Prabhu, Matthias Bönisch, Marc Seefeldt, Martin Diehl, Kim Vanmeensel
Despite the significant application potential of laser powder bed fusion (L-PBF) processed Ti-6Al-4V components, a detailed understanding of their deformation mechanisms remains limited. This study investigates the deformation behavior of the {\alpha^\prime} and {\alpha} phases in the as-built and heat-treated specimens, respectively, using in-situ high-energy X-ray diffraction (HEXRD) combined with crystal plasticity modeling. Both phases exhibited similar elastic anisotropy, with the highest modulus along {00.2} and the lowest along {10.0}, although the {\alpha} phase consistently showed higher directional moduli than the {\alpha^\prime} phase. Their plastic deformation responses differed markedly: in the as-built {\alpha^\prime} phase, slip activation followed the sequence prismatic \rightarrow basal \rightarrow pyramidal I \langle c+a \rangle, whereas in the heat-treated {\alpha} phase, the sequence was basal \rightarrow prismatic \rightarrow pyramidal I \langle c+a \rangle. Analyses of full width at half maximum (FWHM) and diffraction peak intensities further supported these observations. Finally, inverse modeling within a crystal plasticity framework was employed to determine slip family–specific critical resolved shear stresses (CRSS), revealing higher CRSS values in the {\alpha^\prime} phase for all slip systems except the prismatic family.
Materials Science (cond-mat.mtrl-sci)
Ab-initio investigation of the interfacial structural, electronic, and magnetic properties of Co$_{2}$MnAl/X (X = MgO and GaAs) heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Amar Kumar, Mitali, Sujeet Chaudhary, Sharat Chandra
The structural, electronic, and magnetic properties of (100)-oriented Co$ _{2}$ MnAl/MgO and Co$ _{2}$ MnAl/GaAs heterostructures are investigated using plane-wave pseudopotential density functional theory. For the Co$ _{2}$ MnAl/MgO, CoCo-MgMg, CoCo-OO, MnAl-MgMg, and MnAl-OO interfaces in top-to-top configurations are studied, while for Co$ _{2}$ MnAl/GaAs, both top-to-top (Co-Ga, Co-As, Mn-Ga, Mn-As, Al-Ga, Al-As) and bridge-site (CoCo-Ga, CoCo-As, MnAl-Ga, MnAl-As) interfaces are considered. The interfacial geometries featuring Co- or CoCo-atomic terminations for the Co2MnAl slab exhibit larger adhesion energies compared to those terminated with Mn-, Al-, or MnAl-atomic terminations. This indicates their greater interfacial stability. In contrast, MnAl-, Mn-, or Al-terminated interfaces preserve near half-metallicity, whereas Co- and CoCo-terminated geometries display a strongly metallic character. All studied interfaces show enhanced magnetic moments relative to their bulk counterparts, primarily arising from interfacial atoms and their nearest neighbours. These findings offer valuable insights for optimizing Co2MnAl-based heterostructures in spintronic applications.
Materials Science (cond-mat.mtrl-sci)
Symmetries in zero and finite center-of-mass momenta excitons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Robin Bajaj, Namana Venkatareddy, H. R. Krishnamurthy, Manish Jain
We present a symmetry-based framework for the analysis of excitonic states, incorporating both time-reversal and space-group symmetries. We demonstrate the use of time-reversal and space-group symmetries to obtain exciton eigenstates at symmetry-related center-of-mass momenta in the entire Brillouin zone from eigenstates calculated for center-of-mass momenta in the irreducible Brillouin zone. Furthermore, by explicitly calculating the irreducible representations of the little groups, we classify excitons according to their symmetry properties across the Brillouin zone. Using projection operators, we construct symmetry-adapted linear combinations of electron-hole product states, which block-diagonalize the Bethe-Salpeter Equation (BSE) Hamiltonian at both zero and finite exciton center-of-mass momenta. This enables a transparent organization of excitonic states and provides direct access to their degeneracies, selection rules, and symmetry-protected features. As a demonstration, we apply this formalism to monolayer MoS$ _{2}$ , where the classification of excitonic irreducible representations and the block structure of the BSE Hamiltonian show excellent agreement with compatibility relations derived from group theory. Beyond this material-specific example, the framework offers a general and conceptually rigorous approach to the symmetry classification of excitons, enabling significant reductions in computational cost for optical spectra, exciton-phonon interactions, and excitonic band structure calculations across a wide range of materials.
Materials Science (cond-mat.mtrl-sci)
39 pages, 2 figures, 1 Table
Charge transfer empties the flat band in 4H$_b$-TaS$_2$ – except at the surface
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-25 20:00 EDT
Mihir Date, Hyeonhu Bae, Alex Louat, Gabriele Domaine, Niels B. M. Schröter, 2 Enrico Da Como, Binghai Yan, Matthew D. Watson
The 4H\textsubscript{b} polytype of TaS$ _2$ is a natural heterostructure of H and T-type layers. Intriguing recent evidence points towards a possibly chiral superconducting ground state, unlike the superconductivity found in other polytypes where the T layers are absent, requiring understanding of the possible contributions of electrons from the T layers. Here we use micro-focused angle resolved photoemission spectroscopy to reveal that the T termination of the 4H\textsubscript{b} structure is metallic, but a subsurface T layer – seen below an H termination and thus more representative of the bulk case – is gapped. The results imply a complete charge transfer of 1 electron per 13 Ta from the T to adjacent H layers in the bulk, but an incomplete charge transfer at the T termination, yielding a metallic Fermi surface with a planar-chiral character. A similar metallic state is found in an anomalous region with likely T-H-H’ stacking at the surface. Our results exclude cluster Mott localisation in either the bulk or surface of 4H$ _b$ -TaS$ _2$ and point to a scenario of superconductivity arising from Josephson-like tunneling between the H layers.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 4 figures
Signatures of spin-glass superconductivity in nickelate (La, Pr, Sm)3Ni2O7 films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-25 20:00 EDT
Haoran Ji, Zheyuan Xie, Yaqi Chen, Guangdi Zhou, Longxin Pan, Heng Wang, Haoliang Huang, Jun Ge, Yi Liu, Guang-Ming Zhang, Ziqiang Wang, Qi-Kun Xue, Zhuoyu Chen, Jian Wang
The discovery of Ruddlesden-Popper (R-P) nickelate superconductors under high pressure heralds a new chapter of high-transition temperature (high-Tc) superconductivity. Recently, ambient-pressure superconductivity is achieved in R-P bilayer nickelate thin films through epitaxial compressive strain, unlocking in-depth investigations into the superconducting characteristics. Here, through electrical transport study, we report the observation of spin-glass superconductivity with hysteretic magnetoresistance and glass-like dynamics in the bilayer nickelate (La, Pr, Sm)3Ni2O7 films. The superconductivity develops in a two-step transition, with onset Tc exceeding 50 K and zero-resistance Tc around 15 K. Remarkably, magnetoresistance hysteresis, indicative of time-reversal symmetry breaking, is observed exclusively during the second-step transition to zero resistance. The hysteresis is observed under both out-of-plane and in-plane magnetic fields with significant anisotropy, and exhibits coalescing minima at zero field, fundamentally distinct from trapped vortices or long-range-ordered magnetism with coercivity. Successive oxygen reductions simultaneously suppress the superconductivity and hysteresis, revealing their mutual connections to the selective electronic orbitals. The removal of magnetic field triggers spontaneous and logarithmically slow resistance relaxations in the second-step transition, signatures of glassy dynamics, indicating that the superconducting ground state is correlated with an electronic spin-glass order. Our findings uncover an unprecedented superconducting state in the nickelate superconductors, providing phenomenological and conceptual advances for future investigations on high-Tc superconductivity.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Universal Entanglement Pattern Formation via a Quantum Quench
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Lihui Pan, Jie Chen, Chun Chen, Xiaoqun Wang
We identify a universal short-time structure in symmetry-resolved entanglement dynamics – the entanglement channel wave (ECW) – arising from the decomposition of entanglement into conserved-quantum-number sectors that host robust, channel-specific patterns. Focusing on domain-wall melting, we conduct a systematic investigation across three paradigmatic classes of many-body systems: U(1) fermions, U(1) bosons, and SU(2) spinful fermions. For each class, we explore four distinct regimes defined by the presence or absence of interactions and disorder, employing both the Krylov-subspace iterative method and the correlation matrix approach. The ECW emerges universally across all cases, establishing its independence from particle statistics, interaction strength and disorder. In free fermions, the ECW formalism further enables analytical determination of the correlation matrix spectrum. The subsequent melting of the ECW exhibits symmetry- and statistics-dependent signatures, revealing finer structures in the growth of symmetry-resolved entanglement.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Getting the manifold right: The crucial role of orbital resolution in DFT+U for mixed d-f electron compounds
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Kinga Warda, Eric Macke, Iurii Timrov, Lucio Colombi Ciacchi, Piotr M. Kowalski
Accurately modeling compounds with partially filled $ d$ and $ f$ shells remains a hard challenge for density-functional theory, due to large self-interaction errors stemming from local or semi-local exchange-correlation functionals. Hubbard $ U$ corrections can mitigate such errors, but are often detrimental to the description of hybridized states, leading to spurious force contributions and wrong lattice structures. Here, we show that careful disentanglement of localized and delocalized states leads to accurate predictions of electronic states and structural distortions in ternary monouranates (AUO$ _4$ , where A represents Mn, Co, or Ni), for which standard $ U$ corrections generally fail. Crucial to achieving such accuracy is a minimization of the mismatch between the spatial extension of the projector functions and the true coordination geometry. This requires Wannier-like alternatives to atomic-orbital projector functions, or corrections of Hubbard manifolds exclusively comprised of the most localized A-$ 3d$ , U-$ 5f$ and O-$ 2p$ orbitals. These findings open up the computational prediction of fundamental properties of actinide solids of critical technological importance.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Phonon studies of the phase transition sequence in antiferroelectric single crystal of Pb(Hf0.83Sn0.17)O3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Anirudh K.R., Cosme Milesi-Brault, Christelle Kadlec, Dmitry Nuzhnyy, Andrzej Majchrowski, Magdalena Krupska-Klimczak, Irena Jankowska-Sumara, Elena Buixaderas
The sequence of phase transitions in PbHf0.83Sn0.17O3 has been studied by THz, far infrared and Raman spectroscopies, revealing the complementary behaviour of both, polar and non-polar phonons and their impact on the transition lattice dynamics. Pb atom is sensitive to all phase transitions, changing its dynamics with temperature. As temperature decreases, the crystal undergoes a sequence of three phase transitions. The first one to an intermediate (IM) phase, in which polar fluctuations are detected by THz and IR spectroscopy at frequencies below 100 cm-1 contributing to the maximum of permittivity and revealing important softening. Additional antipolar Pb fluctuations and softening were detected by Raman spectroscopy. At lower temperature, another transition to an antiferroelectric (AFE2) phase is revealed by nonpolar soft modes (antipolar and antiferrodistortive ones), and by an important drop of the dielectric strength of polar phonons. The final transition to the antiferroelectric phase (AFE1) is revealed by the appearance of new modes and a sudden change in the frequency of the soft modes when the antipolar shifts become larger. Using symmetry analysis and optical observation to study how the domain pattern changes with temperature, we identified a path for the cubic-AFE2 transition throughout the IM phase, of plausible tetragonal symmetry, driven by an instability from the center of the Brillouin zone. This mechanism coexists with antiferrodistortive instabilities that eventually drive the material into the AFE2 phase. The final phase transition to the AFE1 phase naturally follows from a mode outside the center of the Brillouin zone and a further doubling of the unit cell.
Materials Science (cond-mat.mtrl-sci)
Revealing the Influence of Dopants on the Properties of Fluorite Structure Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Shouzhuo Yang, David Lehninger, Markus Neuber, Amir Pourjafar, Ayse Sünbül, Anant Rastogi, Peter Reinig, Konrad Seidel, Maximilian Lederer
Fluorite structure ferroelectrics, especially hafnium oxide, are widely investigated for their application in non-volatile memories, sensors, actuators, RF devices and energy harvesters. Due to the metastable nature of the ferroelectric phase in these materials, dopants and process parameters need to be optimized for its stabilization. Here, we present clear evidence of how dopants affect the properties in this material system and solutions to achieve improved reliability, desired crystallization behavior and polarization hysteresis shape/position through co-doping. Finally, the benefits of co-doping in a variety of application fields are demonstrated.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
16 pages, 5 figures
Tracking flat bands via phonon-mediated interband scattering
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Fabian Garmroudi, Xinlin Yan, Silke Paschen, Sean M. Thomas, Eric D. Bauer, Andrej Pustogow, Priscila F. S. Rosa
Flat-band (FB) materials have emerged as promising platforms for exploring exotic quantum phases. While numerous candidates have recently been identified through spectroscopic techniques such as angle-resolved photoemission spectroscopy, central challenges remain on how to tune FBs towards the Fermi level $ E_F$ and to understand their impact on low-energy excitations probed in electronic transport experiments. Here, we show that, by attributing the temperature dependence of the electrical resistivity at elevated temperatures to electron-phonon interband scattering, one can infer the position of FBs near $ E_F$ across diverse material classes. As charge carriers scatter off phonons, interband transitions into FB states lead to distinctive sub- or superlinear resistivity at elevated temperatures, governed by the proximity of the FB to $ E_F$ . Our phenomenological model captures these universal transport behaviors observed across several recently studied FB compounds and offers a simple, broadly applicable method for detecting flat bands.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Correlation thresholds in the steady states of particle systems and spin glasses
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
A growing body of theoretical and empirical evidence shows that the global steady-state distributions of many equilibrium and nonequilibrium systems approximately satisfy an analogue of the Boltzmann distribution, with a local dynamical property of states playing the role of energy. The correlation between the effective potential of the steady-state distribution and the logarithm of the exit rates determines the quality of this approximation. We demonstrate and explain this phenomenon in a simple one-dimensional particle system and in random dynamics of the Sherrington-Kirkpatrick spin glass by providing the first explicit estimates of this correlation. We find that, as parameters of the dynamics vary, each system exhibits a threshold above and below which the correlation dramatically differs. We explain how these thresholds arise from underlying transitions in the relationship between the local and global “parts” of the effective potential.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Probability (math.PR)
12 pages, 5 figures
Exploring null-entropy events: What do we learn when nothing happens?
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-25 20:00 EDT
Abhaya S. Hegde, André M. Timpanaro, Gabriel T. Landi
Fluctuation theorems establish that thermodynamic processes at the microscale can occasionally result in negative entropy production. At the microscale, another distinct possibility becomes more likely: processes where no entropy is produced overall. In this work, we explore the constraints imposed by such null-entropy events on the fluctuations of thermodynamic currents. By incorporating the probability of null-entropy events, we obtain tighter bounds on finite-time thermodynamic uncertainty relations derived from fluctuation theorems. We validate this framework using an example of a qudit SWAP engine.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
10 pages, 4 figures
Machine Learning Time Propagators for Time-Dependent Density Functional Theory Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-25 20:00 EDT
Time-dependent density functional theory (TDDFT) is a widely used method to investigate electron dynamics under external time-dependent perturbations such as laser fields. In this work, we present a novel approach to accelerate electron dynamics simulations based on real time TDDFT using autoregressive neural operators as time-propagators for the electron density. By leveraging physics-informed constraints and featurization, and high-resolution training data, our model achieves superior accuracy and computational speed compared to traditional numerical solvers. We demonstrate the effectiveness of our model on a class of one-dimensional diatomic molecules under the influence of a range of laser parameters. This method has potential in enabling real-time, on-the-fly modeling of laser-irradiated molecules and materials with varying experimental parameters.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Computational Physics (physics.comp-ph)
20 pages, 5 figures
Chiral charge density wave in 4Hb- and 1T-TaS$_2$: The Role of interlayer coupling
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-25 20:00 EDT
Roni Anna Gofman, Abigail Dishi, Hyeonhu Bae, Yuval Nitzav, Ilay Mangel, Nitzan Ragoler, Sajilesh K.P., Alex Louat, Matthew D. Watson, Cephise Cacho, Dmitry Marchenko, Andrei Varykhalov, Irena Feldman, Binghai Yan, Amit Kanigel
We use micro-angle-resolved photoemission spectroscopy (micro-ARPES) to investigate chiral charge density waves (CDWs) in 4Hb-TaS$ _2$ with micron-scale spatial resolution. In the 1T layers of 4Hb-TaS$ _2$ , we uncover coexisting left- and right-handed CDW domains and resolve four distinct spectral patterns arising from the interplay of chirality and rotational stacking. In contrast, bulk 1T-TaS$ _2$ exhibits a uniform chirality. In addition, 4Hb-TaS$ _2$ shows negligible out-of-plane dispersion of the 1T-derived bands, in contrast to the pronounced interlayer coupling observed in bulk 1T-TaS$ _2$ . Density functional theory (DFT) calculations corroborate this picture, revealing that the interlayer interaction of the chiral order in 4Hb-TaS$ _2$ is nearly two orders of magnitude weaker than in the 1T polytype. Our findings establish 4Hb-TaS$ _2$ as a quasi-two-dimensional platform for exploring tunable chiral CDW phenomena.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
* These authors contributed equally
Persistence of Coffee-Ring Deposits in Concentrated Suspensions of Anisotropic Colloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-25 20:00 EDT
Samuel S. Nielsen, Brian C. Seper, Michelle M. Driscoll
When droplets of colloidal suspensions evaporate, the suspended colloids are transported to the edge of the drop by an outward radial flow. The resulting dried deposit has a high concentration of colloids along it’s perimeter, and a low concentration near the center. This effect has been dubbed the coffee-ring effect [Deegan et al., Nature, 1997, 389, 827], and is undesirable in applications such as inkjet printing, where a smooth deposition would lead to more efficient coatings. Previous attempts at suppressing this effect using particle anisotropy have paradoxically shown that anisotropic particles can (1) form even deposits [Yunker et al., Nature, 2011, 476, 308] and (2) enhance the coffee ring effect [Dugyala et al., J. Phys. Chem. B, 2014, 119, 3860]. Here we use surface profilometry data to characterize the width of the dried deposits containing rod-shaped silica colloids of aspect ratios ranging from 1 to 20. We observe deposits over a broad range of concentrations (up to 0.35 volume fraction), and find that the width of the ring is independent of the particle anisotropy, even at previously unexplored high volume fractions. We also observe that polystyrene spheres form more even deposits than silica spheres when evaporated at high temperatures. This result serves to unify the literature by identifying a key parameter in controlling the deposit shape: the difference between the sedimentation velocity of colloids in solution and the velocity of the air-water interface.
Soft Condensed Matter (cond-mat.soft)