CMP Journal 2026-06-29
Statistics
Nature: 1
Nature Physics: 2
arXiv: 61
Nature
Family of magnetic field-boosted superconductors in rhombohedral graphene
Original Paper | Electronic properties and materials | 2026-06-28 20:00 EDT
Junseok Seo, Armel A. Cotten, Shenyong Ye, Mingchi Xu, Omid Sharifi Sedeh, Henok Weldeyesus, Tonghang Han, Zhengguang Lu, Zhenghan Wu, Wei Xu, Jixiang Yang, Emily Aitken, Prayoga P. Liong, Phatthanon Pattanakanvijit, Zach Hadjri, Rasul Gazizulin, Kenji Watanabe, Takashi Taniguchi, Mingda Li, Dominik M. Zumbühl, Long Ju
In some unconventional superconductors, time-reversal symmetry can be broken in addition to the gauge symmetry1, resulting in superconductivities that can be enhanced or induced by magnetic fields2. However, field-enhanced superconductors are more vulnerable to impurities than Bardeen-Cooper-Schrieffer counterparts3. Crystalline rhombohedral multilayer graphene is a promising platform to explore them due to its superior material quality and gate-tunable strong correlation effects4,5. Here we report transport measurements of rhombohedral tetralayer and pentalayer graphene, demonstrating a spectrum of clean-limit superconductivities. We found three different types of field-enhanced and field-induced superconductivities in the pentalayer. They are all robust against an in-plane field up to 8.5 Tesla, exceeding the Pauli limit by tens of times. Compared to Bernal bilayer graphene showing only in-plane field-enhancement6, pentalayer graphene features superconductors enhanced by out-of-plane as well as in-plane fields. They also reside at much lower gate electric fields owing to the intrinsically flatter band dispersion–facilitating their study and further engineering. Additionally, we observed that proximitized spin-orbit coupling (SOC) generates multiple new superconductors without introducing additional disorder effects. Our work establishes a new family of magnetic field-boosted superconductors in rhombohedral graphene. Utilizing the high accessibility with moderate gate voltages, this will pave the way for realizing non-Abelian quasiparticles through interfacial engineering7 in the extreme clean limit, in that proximitized SOC leads to topological states8 and maintains the ultrahigh quality of crystalline graphene.
Electronic properties and materials, Superconducting properties and materials
Nature Physics
Surface d-orbital order in an intermetallic compound
Original Paper | Electronic properties and materials | 2026-06-28 20:00 EDT
Zhanyang Hao, Haohao Sheng, Wanru Ma, Wengen Zheng, Yongqing Cai, Zijuan Xie, Wanlin Cheng, Zuowei Liang, Wu Xie, Wenjuan Zhao, Chen Liu, Zhibin Su, Junhao Lin, Liusuo Wu, Zhengtai Liu, Mao Ye, Ji Dai, Massimo Tallarida, Shengtao Cui, Yogendra Kumar, Kenya Shimada, Kenichi Ozawa, Shuki Torii, Kazuhiro Mori, Yue Xie, Junze Deng, Jiaou Wang, Xuetao Zhu, Jiandong Guo, Jiawei Mei, Zhenyu Wang, Xianhui Chen, Ping Miao, Zhijun Wang, Chaoyu Chen
Orbital order describes a quantum state where occupied orbitals line up in a periodic pattern. Although orbital physics plays a fundamental and universal role in strongly correlated electron systems, the existence and particularly the band-structure fingerprint of orbital order remain a long-standing mystery. Here we report the discovery of rare earth 5d-orbital order developed by the surface states of the intermetallic compound Tb2CoAl4Ge2. Angle-resolved photoemission spectroscopy reveals characteristic nematic features such as Fermi surface deformation and band splitting. These experimental observations can be described by a ferro-orbital order term in the mean-field Hamiltonian. The structural and magnetic origin of such order is excluded by systematic high-resolution neutron powder diffraction and scanning tunnelling microscopy measurements. Our results provide strong evidence for a pure surface orbital order scenario avoiding complications from structural distortion as in colossal magnetoresistance manganites, magnetic order as in iron-based superconductors and charge transfer p-orbital order in cuprates.
Electronic properties and materials, Surfaces, interfaces and thin films
Exchange-mediated spin-electric control of single molecules on surfaces
Original Paper | Organic-inorganic nanostructures | 2026-06-28 20:00 EDT
Paul Greule, Wantong Huang, Máté Stark, Kwan Ho Au-Yeung, Johannes Schwenk, Jose Reina-Gálvez, Christoph Sürgers, Wolfgang Wernsdorfer, Christoph Wolf, Philip Willke
Individual magnetic molecules are promising building blocks for quantum technologies owing to their chemical tunability, nanoscale dimensions and ability to self-assemble into ordered arrays. However, exploiting their properties in quantum information processing requires precise local control of their spin. Here we demonstrate spin-electric coupling for two molecular spin systems–iron phthalocyanine (FePc) and Fe-FePc complexes–adsorbed on a surface. We use electron spin resonance combined with scanning tunnelling microscopy to locally address them and electrically tune them using an applied bias voltage. These measurements reveal a nonlinear voltage dependence of the resonance frequency, linked to the energetic position of the molecular orbitals. We attribute this effect to a transport-mediated exchange field from the magnetic tip, providing a large, highly localized and broadly applicable spin-electric coupling mechanism. Finally, we demonstrate that the spin-electric coupling enables all-electrical coherent spin control. In Rabi oscillation measurements of both single and coupled Fe-FePc complexes, we show that the spin dynamics can be tuned using the exchange field, demonstrating a pathway towards electrically controlled quantum operations.
Organic-inorganic nanostructures, Quantum information
arXiv
Elimination of Flux Trapping in Superconducting Circuits in Ambient Magnetic Fields
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-29 20:00 EDT
Rohan T. Kapur, Alex Wynn, Sergey K. Tolpygo, Neel Parmar, Anil Mankame, Adam A. Libson, Rabindra Das, Michele Kelley, Pauli Kehayias, Nathaniel J. O’Connor, Collin N. Muniz, Justin L. Mallek, Jennifer M. Schloss
Superconductor digital electronics and quantum computing with superconducting qubits are promising next-generation computing technologies. When cooled down or operated in the presence of a nonzero background magnetic field $ B_r$ , superconducting thin films comprising the circuits can trap magnetic vortices that can degrade circuit or qubit performance. In this work, we report a practical solution for eliminating flux trapped during cooldown in ambient magnetic fields, $ B_r\leq 60$ $ \upmu$ T, based on controlled local thermal gradients and moats, etched holes in the superconducting films of the circuit. Thermal gradients created by integrated on-chip resistive heaters move vortices towards the moats, where they become trapped away from circuitry regions and pinning sites. Using magnetic imaging and electrical circuit readout, we demonstrate that this approach is capable of removing magnetic flux trapped during field cooling and magnetic flux nucleated by circuit operation. If used in an environment with basic magnetic shielding, this solution is capable of suppressing all magnetic flux in a large-scale circuit, overcoming one of the long-standing challenges preventing high-performance scalable computing using superconductors.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
Magnetic long-range order at finite temperature in two-dimensional hyperbolic lattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
Alexander Hickey, Joseph Maciejko
Infrared singularities of gapless Goldstone modes preclude magnetic long-range order at finite temperature in conventional two-dimensional systems. By studying the spin-$ S$ Heisenberg model on regular tilings of the hyperbolic plane, we show that this obstruction is absent in negatively curved space. Using spin-wave theory, we find that the zero-energy collective modes required by symmetry carry vanishing local spectral weight and are separated from the thermodynamic bulk magnon continuum by a finite gap in the bulk local spectral density. As a result, local transverse correlations remain short ranged, with a finite correlation length, despite the presence of Goldstone modes associated with the broken SO(3) spin-rotation symmetry. Stronger negative curvature is found to suppress quantum fluctuations in bulk thermodynamic quantities, pushing the ordered state toward “mean-field-like” behavior. We further estimate the ordering temperature from the thermal spin-wave correction to the ordered moment. These results establish hyperbolic geometry as a route to finite-temperature magnetic order that circumvents the Mermin-Wagner obstruction without breaking or modifying the continuous symmetry.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
30 pages, 15 figures
Collection, characterization, and precision measurement of levitated charged nanoparticles
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
B. E. Kane, Joyce Coppock, Sunghyun Kim, Sarah Westgate
We describe apparatus and experimental procedures for high stability precision measurements of levitated nanoscale particles confined in an ion trap in high vacuum. We discuss methods for particle generation and collection using electrospray emission, for rapid characterization by direct imaging of thermal motion, and for transfer of the particle from the trap where it is collected to a separate analysis trap in order to achieve better vacuum and lower noise. In the analysis trap at high vacuum (pressure $ p\simeq10^{-8}$ Torr), we employ thermostatic control of the trapped particle oscillation amplitudes, allowing long-term, precision measurements of oscillation frequencies, from which the charge to mass ratio ($ Q/M$ ) can be deduced. Under these conditions, we achieve $ Q/M$ measurement precision approaching $ 10^{-5}$ . This sensitivity will enable, for example, investigations of the surface chemistry of $ \mu$ m-scale levitated materials in ultra-high vacuum environments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Instrumentation and Detectors (physics.ins-det)
12 pages, 12 figures. Movie version of Figure 7 is available in ancillary files
Jarzynski equality for counterwork under reversed memory-filtered driving
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
We introduce a counterwork functional generated by a sign-inverting memory-filtered effective protocol. Given an imposed protocol $ \lambda(t)$ , the effective protocol $ \Lambda(t)$ is obtained by applying an active protocol-memory kernel to $ \dot{\lambda}(t)$ , rather than by invoking a passive bath response. The counterwork is then the ordinary Hamiltonian work associated with $ H(\Gamma,\Lambda(t))$ , so that Jarzynski’s equality applies directly to it. When $ \Lambda(t)$ reverses the endpoints of $ \lambda(t)$ , the corresponding free-energy difference satisfies $ \Delta F_C=-\Delta F_W$ , and the exponential average of the counterwork is the reciprocal of that of the original work. We derive the kernel normalization realizing this reversed displacement and show, by Jensen’s inequality, that the product of the exponentials of the average work and counterwork is bounded by unity, implying $ \langle C\rangle+\langle W\rangle\geq0$ . Thus negative average counterwork is possible only when compensated by the average work of the original operation. We further discuss the counteroperation under incomplete thermodynamic information, showing that the robust strategy is to enforce endpoint reversal while minimizing dissipated counterwork.
Statistical Mechanics (cond-mat.stat-mech)
7 pages
SU(4) Heisenberg model on the hyperhoneycomb lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
We study the ground state of the SU(4) Heisenberg model on the hyperhoneycomb lattice using three-dimensional projected entangled pair states. We show that it is possible to compute physical observables for the ground states using loop expansions, which converge quickly on tree-like lattices. Our extrapolations to the limit of infinite bond dimensions point toward gapless spin-liquid ground state.
Strongly Correlated Electrons (cond-mat.str-el)
Ultrafast non-thermal suppression of ferroelectricity by carrier screening in LiNbO3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Man Tou Wong, Zhuquan Zhang, Zi-Jie Liu, Keith A. Nelson
Ferroelectric materials are key to energy-efficient electronics, memory, and optical applications. While charge carriers typically screen and suppress ferroelectricity, their role under nonequilibrium conditions remains elusive. Here, we use femtosecond laser pulses to liberate trapped carriers in LiNbO3 and track the response using time-resolved second-harmonic generation and stimulated Raman scattering. Even dilute photoexcited carriers induce a rapid yet enduring suppression of polarization and Raman susceptibility. Fluence- and temperature-dependent analyses confirm the suppression is non-thermal and arises from transient carrier screening. These findings reveal an efficient, reversible, and symmetry-preserving mechanism to modulate ferroelectricity on ultrafast timescales, offering a new route to control ferroic and competing quantum phases.
Materials Science (cond-mat.mtrl-sci)
Mapping the Growth of Two-Dimensional $π$-Conjugated Polymers on Au(111): Organometallic Intermediates and Edge Terminations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Simon W. Briesenick, Wyatt A. Behn, Manuel González Lastre, Chang Wan Kang, Pablo Pou, Ekaterina D. Ulyanov, Rubén Pérez, Dmytro F. Perepichka, Peter Grutter
Kagome lattices provide an exciting space for the exploration of graphene-like $ \pi$ -conjugated molecular systems with flat bands. Using heterotriangulene-derived precursors, along with an on-surface Ullmann coupling process, makes growing polymers with Kagome lattices accessible and straightforward. Here, we use scanning tunneling microscopy alongside high-resolution atomic force microscopy to examine the evolution of tribromotrioxaazatriangulene on Au(111) into ordered, covalent films. Using density functional theory and scanning probe methods, we find previously unreported organometallic intermediate states involving Au adatoms incorporated within the growing polymer lattice. We also find that a majority of polymer edges remain brominated up to 250 $ ^{\circ}$ C and a large number of edges bonded to Au adatoms coordinated to an adjacent bromine atom. These observations suggest that residual bromine could play a role in stabilizing the polymer edges to Au adatoms and thereby influence the growth pathways that lead to ordered Kagome polymer lattices.
Materials Science (cond-mat.mtrl-sci)
A BRAVE Alloy Design Campaign (Bayesian Risk-aware Alloy discoVery and Exploration)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Mrinalini Mulukutla (a), Danial Khatamsaz (a), Trevor Hastings (a), Wenle Xu (a), Daniel Salas (a), Joydeep Kundu (a), Vasanth C. Shunmugasamy (a), Daniel Lewis (a), Jacob Hempel (a), Clinton Strosser (a), Alexandra Salinas (b), Brent Vela (a), Nicolas Flores (a), Sina Hossein Zadeh (a), Ali Rachidi (d), David Elbert (d), Brady Butler (c), James Paramore (e), Dimitris Lagoudas (a), Justin Wilkerson (b), George Pharr (a), Douglas Allaire (b), Vahid Attari (a), Ibrahim Karaman (a), Ankit Srivastava (a), Raymundo Arróyave (a, b) ((a) Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA, (b) Mechanical Engineering Department, Texas A&M University, College Station, TX, USA, (c) DEVCOM Army Research Laboratory South at Texas A&M University, College Station, TX, USA, (d) Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, Maryland,, USA, (e) Bush Combat Development Complex, Texas A&M University System, TAMU, College Station, TX, USA)
In constrained alloy optimization, the compositions with the highest performance potential often reside at the boundary of phase stability – where the risk of experimental failure is also highest. This work demonstrates this principle through a risk-aware Bayesian optimization campaign on single-phase FCC high-entropy alloys in the Al-V-Cr-Mn-Fe-Co-Ni-Cu system. A learned feasibility classifier, integrated directly into the multi-objective acquisition function, probabilistically penalizes candidates likely to produce failed experiments while preserving access to high-performing boundary compositions. From approximately 27,000 CALPHAD-screened candidates, 48 alloys were synthesized over three closed-loop iterations targeting five objectives (yield strength, UTS/YS ratio, strain at UTS, dynamic-to-quasi-static hardness ratio, and simulated depth of penetration), exploring 0.12% of the feasible space. Two compositional regimes emerged: a V-rich, Ni-rich high-strength regime (UTS up to $ {\sim}1480$ MPa at 50% elongation) and a Mn-containing high-ductility regime (UTS/YS up to 4.20 at $ >$ 50% elongation). Among feasible alloys, vanadium simultaneously drives yield strength ($ r = 0.84$ ) and sigma-phase formation ($ r = 0.54$ with infeasibility); at V = 24at.%, the three strongest alloys and three sigma failures share the same compositional point. Additionally, the strongest performing alloys cluster in a narrow region of compositional space (V $ \geq$ 20 at.%, Ni $ \geq$ 36 at.%), representing $ {\sim}100$ of $ 27,074$ feasible candidates – a probability of $ P \approx 6.5 \times 10^{-6}$ under random sampling. This dual role – consistent with the KKT prediction that constrained optima lie on active constraint boundaries – required feasibility-aware acquisition to access; hard filtering would have excluded this region entirely.
Materials Science (cond-mat.mtrl-sci)
Main article including appendix - 30 pages. Supplemental information - 24 pages. Link to github repository is included for code and data in the project
Multiphoton Fingerprints of Altermagnetic Spin Splittings
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Sayed Ali Akbar Ghorashi, Andrew M. Rappe
We systematically investigate multiphoton absorption as a polarization-resolved nonlinear optical probe of planar altermagnets (ALMs). We show that the angular harmonic of the altermagnetic spin splitting fixes the lowest optical absorption at which a symmetry-selective response appears: two-photon absorption for $ d$ -wave order, four-photon absorption for $ g$ -wave order, and six-photon absorption for $ i$ -wave order. In each case, there exists a polarization channel locked to the symmetry harmonic of the altermagnetic texture in which the direct $ n$ -photon contribution to the transition matrix element is absent. This changes the frequency scaling of the absorption rate relative to other polarization channels and provides a direct optical fingerprint of the underlying altermagnetic harmonic. Our results establish a hierarchy of nonlinear spectroscopic signatures that distinguishes $ d$ -, $ g$ -, and $ i$ -wave altermagnetic spin splittings beyond linear response.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
4 pages, 1 figure
PtyRANNOSAUR: Ptychography with Robust Artificial Neural Networks Optimized for Sub-Angstrom Accuracy and Ultrafast Reconstruction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Kieran Loehr, Rahim Raja, Xiaochuan Ding, Jeffrey Huang, Gillian Nolan, Sang hyun Bae, Bryan K. Clark, Pinshane Y. Huang
We present PtyRANNOSAUR, a data-driven neural network code that reconstructs atomic resolution electron ptychography data in seconds, 10-100x faster than standard methods. PtyRANNOSAUR uses convolutional autoencoders to map 4D-scanning transmission electron microscopy data to 2D phase images. Each model is trained on a large database of crystal structures and is tailored for a range of experimental parameters, such as accelerating voltage, convergence angle, defocus, and sample thickness. This approach yields high quality reconstructions without requiring any fine-tuning of hyperparameters. In addition, the code handles spatial partial coherence, multiple scattering, and scan position errors, which are critical for state-of-the-art electron ptychography reconstructions. By testing PtyRANNOSAUR on experimental and simulated data, we show that the neural networks accurately reconstruct atomic structures of a broad range of materials systems and can achieve high resolutions of $ <0.5$ Å, comparable to the best iterative reconstructions of the same data. These advances enable near-live, state-of-the-art electron ptychography reconstructions.
Materials Science (cond-mat.mtrl-sci)
28 pages, 5 + 4 figures, 1 + 3 tables
Thermal Corrections and Analysis on the Phase Stability of CsPbCl3 and Cs2AgSbCl6 during In-Situ Thermal Treatment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Ethan R. Cronk, Wenjun Xiang, Rachel Fister, Biswajit Ball, Feng Yan, Liping Yu, Nicholas S. Bingham
Cesium lead chloride (CsPbCl3) is a well known and principal model for inorganic perovskite halide optoelectronic research. The many available techniques including high temperature stability testing have been used to investigate the increasing interest in inorganic perovskites as primary layers in solar cell applications. Due to the nature of high temperature testing, the characterization technique, reproducibility, and the true sample temperature are vital in determining relative stability. By choosing CsPbCl3 in the investigation of the structural stability of perovskites at high temperatures, it acts as a baseline to create and verify a methodology that accurately probes sample temperature, phase transitions, and decomposition onsets. Therefore, we present a methodological approach to investigate the thermal interactions and stability of CsPbCl3 as a parent single perovskite halide based on ligand-assisted re-precipitation synthesis techniques. Where we use our approach to inform and probe thermal interactions in other cesium/chlorine compounds like Cs2AgSbCl6. By analyzing the stoichiometry and initial phases through investigations of the crystalline structure and particle morphology, we calculated temperature conversions using a control substrate and refinements to best estimate changing structure parameters. Using in-situ temperature dependent X-ray diffraction, we were able to effectively probe the phase transitions and decomposition temperatures of the investigated halide powders. Creating a process that can confirm known high temperature structural phenomena of model perovskite halides while verifying our true sample temperature. Which allowed for further testing on the thermal kinetics of on the double perovskite structure Cs2AgSbCl6 and will continue to allow us to test other perovskites and perovskite families of interest in modern high temperature perovskite halide research.
Materials Science (cond-mat.mtrl-sci)
29 pages, 9 figures, supplementary information, 4 supplementary figures
Emergence of millimeter-wave resonances in self-assembled ferroelectric metamaterials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Florian Bergmann, Peter Meisenheimer, Aiden Ross, Marvin Schewe, Fernando Gómez-Ortiz, Kaiwen Yang, Xinyan Li, Thomas J. Lee, Pushpendra Gupta, Liam G.Connolloy, Tzu-Hsuan Hsu, Jack Kramer, Bryan T. Bosworth, Nicholas R. Jungwirth, Eric J. Marksz, Aaron Hagerstrom, Tomasz Karpisz, Arundhati Ghosal, Lane W. Martin, Yimo Han, Angela C. Stelson, Christian J. Long, Ruochen Lu, Lucas Caretta, Javier Junquera, Jason J. Gorman, Long-Qing Chen, Ramamoorthy Ramesh, Nathan D. Orloff
Resonators are a key component in modern communications and computing. As demand and technological advances push component requirements into the terahertz regime, there is significant research devoted to the search for resonances at these frequencies. While uniform solid-state materials usually do not intrinsically feature resonances in this frequency range, self-assembled periodic arrays of ferroelectric nanodomains may provide an engineering route to design millimeter-wave properties. Here, we utilize prototypical dielectric-ferroelectric SrTiO3/PbTiO3 superlattices to robustly design periodic ferroelectric nano-scale domains. Phase field simulations predict an emergent domain breathing mode in complex polar textures and state-of-the-art millimeter-wave characterization shows evidence for such emergent resonances up to hundreds of GHz. Complex polar textures in these superlattices lead to emergent piezoelectric properties that also result in millimeter-wave resonances, which are predicted by second principles methods and confirmed by direct measurement. The principles investigated in this work suggest a new modality for ferroelectrics in the design of millimeter-wave electronics.
Materials Science (cond-mat.mtrl-sci)
40 pages, including 21 main manuscript pages and supplementary
Entropy engineering of BF-BT-based high-entropy ceramics for ultra-high energy storage performance
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Yitao Jiao, Zhenhao Fan, Dawei Wang, Hai-Feng Li
Dielectric capacitors are promising for pulsed power applications, but the energy storage performance of lead-free bulk ceramics is often limited by low breakdown strength and large ferroelectric hysteresis. Herein, a high entropy perovskite oxide BaTi0.2Zr0.2Sn0.2Hf0.2Nb0.1Sc0.1O3 was introduced into the BF-BT matrix to develop lead free high entropy ferroelectric ceramics. Multicomponent B-site substitution induces lattice distortion, enhanced pseudocubic characteristics, relaxor behavior, and grain refinement. These effects suppress polarization hysteresis and electrical conduction, resulting in a significant increase in breakdown strength. A maximum breakdown strength of 840 kV/cm1 and a recoverable energy density of 10.55 J/cm3 were achieved. Entropy-induced microstructural heterogeneity promotes a more uniform electric-field distribution and delays dielectric breakdown. This work demonstrates entropy engineering as an effective route to achieving high breakdown strength and superior energy-storage performance in lead-free ferroelectric ceramics.
Materials Science (cond-mat.mtrl-sci)
11 pages, 10 figures
The Second Law, Symmetry of Time Reversal and Thermodynamic Equilibrium in Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-29 20:00 EDT
The Second law, universally applicable to all states of all sorts of matter and radiation, is undeniably the brightest jewel in the tiara of laws of thermodynamics; recall that the achievements of this law include the principle of least action, the atomistic structure of matter, the quantization of radiant heat, and much more. However, there is a significant gap in understanding the application of the Second law to magnetizing materials, especially to superconductors. This communication is targeted to fill the gap. The concepts of equilibrium and reversibility in thermodynamic processes are considered with particular attention to specifics of superconductivity. These include (1) the primary role of the field strength $ \textbf{H}$ in forming magnetization; (2) the zero entropy of samples in a state of thermodynamic equilibrium; and (3) two kinds of superconducting currents in samples out of equilibrium. As shown, time reversal symmetry in superconductors is a consequence of the Second law and, therefore, is a mandatory property of these materials in a state of equilibrium. Necessary conditions for achieving the latter are framed out. Awareness of these aspects is important for advancing research on superconductivity in all kinds of superconducting materials.
Superconductivity (cond-mat.supr-con)
7 pages, 3 figures
CoTAR: Topology and Atomic State Reconstruction in Condensed Phases
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Hodaka Mori, Yu Miyazaki, Takechika Kikkawa
Universal machine learning interatomic potentials (uMLIPs) enable condensed-phase molecular dynamics (MD) simulations with near-first-principles accuracy, but their lack of explicit molecular topology limits bond-aware analysis and reconnection to classical force fields. Here, we present CoTAR, a hybrid graph neural network (GNN)–hidden Markov model (HMM) framework that reconstructs molecular topology, formal charges, and unpaired electrons from atomic species, coordinates, and total charge by combining message passing on a proximity graph with a van der Waals prior, chemical constraints, and temporal smoothing. Across 128 nonreactive, topology-preserving condensed-phase systems, CoTAR achieved a bond-order-weighted F1 score of 0.906 on classical-MD data; for uMLIP trajectories, few-shot fine-tuning improved the valid-snapshot rate from 38.6% to 84.7%. The reconstructed topologies also supported downstream classical MD simulations, and HMM smoothing improved system-level MD simulation feasibility from 83.6% to 85.9%, indicating that CoTAR provides a practical framework for bond-aware analysis of condensed-phase uMLIP trajectories.
Materials Science (cond-mat.mtrl-sci)
Thickness dependence of diode efficiency in superconducting Fe(Se,Te)/FeTe thin-film heterostructure devices
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-29 20:00 EDT
Kaito Arizono, Kenshin Inamura, Kouta Kondou, Yusuke Kobayashi, Tsutomu Nojima, Jobu Matsuno, Junichi Shiogai
The superconducting diode effect (SDE) is a nonreciprocal transport phenomenon, in which the superconducting critical current density depends on the polarity of the current. It has attracted recent attention because of its potential applications to a rectifier without energy dissipation. While SDE has been observed in a wide range of superconducting materials with broken inversion symmetry as well as thin-film heterostructures, the microscopic origin linking structural inversion asymmetry of electronic band, spin-orbit interaction, and vortex pinning remains to be clarified. In this study, we investigate SDE in Fe(Se,Te)/FeTe heterostructure devices as a function of the superconducting Fe(Se,Te) layer thickness tFST to elucidate the role of structural inversion asymmetry on the vortex-induced SDE. We find that the SDE efficiency monotonically increases with increasing tFST, which can be understood by considering that the band bending in the bulk Fe(Se,Te) layer induces the structural inversion asymmetry and thus, the Rashba spin-orbit interaction. In addition, we demonstrate almost 100% rectification for the Fe(Se,Te)/FeTe heterostructure devices in half- and full-wave oscillation configurations. Our findings point out the importance of structural architecture for realization of highly efficient SDE devices based on superconducting thin-film heterostructures.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
30 pages, 5 figures, and supplementary materials
Circularly Polarized Magneto-Photoluminescence in Two-Dimensional Chiral Perovskites R- and S-(C4H9NH3)2PbI4 under High Magnetic Fields
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
D. Y. Park, S. Park, Yongmin Kim, N. Myoung, Z. Yang, Y. Kohama, Y. H. Matsuda
We report circularly polarized magneto-photoluminescence (MPL) measurements on the enantiomeric pair of two-dimensional chiral perovskites R- and S-(C4H9NH3)2PbI4 in pulsed magnetic fields up to 50 T at 4.2 K. The R-form exhibits strong preferential emission into the RC channel (I_RC/I_LC = 10:1), with the S-form showing the opposite sense, robust against the applied field. Three key observations are reported: (i) an anomalous redshift of all exciton transition energies with increasing field-contrasting with the normal diamagnetic blueshift of achiral perovskites-with a non-monotonic initial blueshift to 7.6 T in the dominant RC channel of the R-form; (ii) complete invariance of PL peak positions upon reversal of the field direction, consistent with Rashba-induced mixing of the bright exciton with a nearby m_x = 0 dark state; and (iii) field-induced increase in PL intensity and narrowing of the linewidth, attributed to suppression of disorder scattering as the cyclotron orbit contracts. These results are interpreted in the framework of Rashba spin-splitting and polaron formation in the chiral two-dimensional perovskite lattice.
Materials Science (cond-mat.mtrl-sci)
Amorphous Fe-Sn nanofilms for anomalous-Nernst heat-flux sensing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Kenji Tanabe, Ko Mibu, Atsushi Tsukazaki, Kohei Fujiwara
Amorphous magnetic films are promising for anomalous-Nernst heat-flux sensing because their low thermal conductivity can enhance the temperature gradient generated by an applied heat flux. However, amorphization often degrades electronic transport and thermoelectric properties, making it challenging to obtain a large anomalous Nernst response in structurally disordered films. Here, we demonstrate nanometer-thick amorphous Fe-Sn films as high-sensitivity anomalous-Nernst heat-flux sensing materials. By systematically controlling composition and thickness, we find that amorphous Fe-Sn nanofilms combine a large anomalous Nernst response with low thermal conductivity, resulting in a heat-flux sensitivity of 0.37 um/A. This value exceeds the sensitivities reported for both amorphous magnetic thin films and representative crystalline topological magnets. X-ray diffraction and Mossbauer spectroscopy show that the optimized films lack long-range crystallinity while retaining local Fe-Sn environments, suggesting that short-range atomic order contributes to the anomalous Nernst response in the amorphous matrix. The sensitivity is also reproduced on flexible polymer substrates, indicating compatibility with mechanically compliant device architectures. These results establish amorphous Fe-Sn nanofilms as a platform for anomalous-Nernst heat-flux sensing and provide a materials design route based on local-structure control and thermal-conductivity reduction.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Vacancy-mediated nitrogen diffusion and aggregation via high-fluence electron beam irradiation in HPHT synthesized diamond crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Chikara Shinei, Yuta Masuyama, Jun Chen, Hiroshi. Abe, Masashi Miyakawa, Takashi Taniguchi, Takeshi Ohshima, Tokuyuki Teraji
The negatively charged nitrogen vacancy (NV-) center in diamonds is promising point defect for highly sensitive quantum sensing. The formation of high-density NV- centers is essential for improving sensitivity. We performed room-temperature electron beam irradiation (EBI) and annealing on nitrogen-doped high-pressure high-temperature diamond crystals to convert substitutional nitrogen into NV centers. In the low-fluence region of EBI, neutral substitutional nitrogen (Ns0) concentration decreased and NV0 and NV- center concentration increased with increasing EBI fluence. The decrease in Ns0 concentration was comparable to the increase in total NV center concentration; thus, the conversion from Ns0 to NV0 and NV- centers is a dominant defect formation process. In a high-fluence region, NV0 and NV- center and Ns0 and Ns+ concentrations decreased with increasing EBI fluence, indicating the formation of unknown nitrogen-related defects such as the H3 center, which is a nitrogen and vacancy aggregation defect. Although H3 centers were observed at high EBI fluence, their forming annealing temperature of 1375 +- 25 degrees Celsius was lower than the typically reported temperatures over 1600 degrees Celsius. We attribute this low-temperature formation to vacancy-mediated nitrogen diffusion and aggregation.
Materials Science (cond-mat.mtrl-sci)
Three-dimensional visualization of threading dislocation in GaN by polarized-light microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Yukari Ishikawa, Kisara Matsumoto, Kazuki Ohnishi, Yongzhao Yao
We demonstrate high-throughput three-dimensional imaging of threading dislocations in ammonothermal GaN wafers using polarized-light microscopy with collimated LED illumination. Threading dislocations exhibited focal-depth-dependent in-plane shifts, enabling visualization of their three-dimensional inclination behavior over large areas. Synchrotron radiation X-ray topography indicated that dislocations with identical in-plane Burgers vector components tended to exhibit similar trace geometries and inclination directions. The threading dislocations were found to be tilted by approximately 3.3° from the c-axis in directions perpendicular to their Burgers vectors, indicating climb-mediated motion associated with strain relaxation during crystal growth. These results demonstrate a simple nondestructive approach for large-area three-dimensional characterization of dislocations in GaN wafers.
Materials Science (cond-mat.mtrl-sci)
17 pages, 5 figures
Collision and coalescence dynamics of bosonic quantum Hall droplets
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-29 20:00 EDT
Xinyi Liu, Zhendong Li, Yuwen Zhou, Siying Li, Haoran Xu, Zihe Liu, Rongzhen Jiao, Mingyuan Sun
Recently bosonic quantum Hall droplets have been observed in rapidly rotating two-dimensional Bose-Einstein condensates (BECs), which exhibit robust dynamical stability. Inspired by this, we systematically investigate the collision and coalescence dynamics of these droplets within the Gross-Pitaevskii framework. For two-droplet collisions, we find two distinct collision outcomes, namely merging and separation, that are controlled by the initial relative velocity. The critical velocity exhibits a universal scaling law with the interaction and the particle number as $ v_c \propto (gN)^{1/4}$ , which can be interpreted from a simplified analytical model, revealing the essential role of the collision time. It differs fundamentally from the mechanism governing the conventional Lee-Huang-Yang stabilized quantum droplets. Furthermore, while the collision can change the shape of the droplet significantly, the center of mass trajectory remains nearly unaffected, owing to the conservation of angular momentum. For overlapping stationary droplets, vortex arrays can emerge through Kelvin-Helmholtz instability driven by phase-induced shear flow. Although two droplets may merge into a larger one, extended states cannot be constructed from multiple overlapping droplets. Instead, the system dynamically reorganizes into new isolated droplets, revealing the localized property in the bulk region. Our results reveal the unique nonequilibrium dynamics of quantum Hall droplets and suggest new pathways for manipulating strongly correlated rotating quantum fluids.
Quantum Gases (cond-mat.quant-gas)
9 pages, 9 figures
Confined exciton polaron in MoS$_2$ on twisted-hBN
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Garima Gupta, Mayank Chhaperwal, Pankaj Kumar, Pushkar Dasika, Kenji Watanabe, Takashi Taniguchi, Archana Raja, Kausik Majumdar
The simple electrostatic picture of a trion is that of an excess charge inducing an exciton polarization and binding closer (farther) to the hole (electron) side of it. Trion formation can be forbidden when such spontaneous rearrangement of charges is not allowed by the application of external perturbation, such as electric field. Here we test this hypothesis experimentally using a non-monotonic electric field. We realize this scenario by imprinting the ferroelectric domains at the AA-stacked twisted-hBN (t-hBN) interface onto a monolayer of MoS2 placed over it. The spatially varying in-plane electric field around the domain wall serves the dual purpose of (a) confining and polarizing the 2D exciton in the domain wall, and (b) depleting the free charge carriers from the domain wall. We observe a large quantized exciton splitting confirming strong exciton confinement in the domain wall. Forced by the confining potential, the electron side of the polarized exciton lies closer to the domain with accumulated free electrons, which should ideally prevent any trion formation. Contrary to the laid hypothesis, we observe signatures of quantized charged exciton emission, with an inter-level splitting that mimics the level-splitting of the quantized excitons. This paradox is explained using the many-body picture of exciton polaron, where a conduction band hole attractively binds the polarized exciton and the electron Fermi sea. The results provide a definitive way to unambiguously discern exciton polaron from trion.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Non-Newtonian two-dimensional electron fluid in magnetic field
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
We predict a mechanism for the non-Newtonian behavior of a two-dimensional (2D) electron fluid due to the local Joule heating of electrons. Within this mechanism, the electron shear viscosity is a non-monotonic function of the velocity gradient. This means that 2D electrons form an unusual non-Newtonian fluid, either dilatant or pseudoplastic, depending on the flow regime. We construct and solve the hydrodynamic equations for a hydrodynamic velocity and a corresponding temperature profile for a Poiseuille-like flow geometry. We demonstrate that the considered non-Newtonian non-linearity induced by the local heating is apparently responsible for the nontrivial differential magnetoresistance observed for 2D electrons in ultra-high-quality GaAs quantum wells, so we conclude that a 2D non-Newtonian electron fluid is realized in these systems at high currents.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 3 figures
Eigenvalue Statistics of Random Quantum Geometry
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
The quantum geometric tensor is a fundamental property of quantum states, with broad applications in condensed matter physics, topological phases, and quantum phase transitions. The eigenvalues characterize the scale, anisotropy, and effective rank of random quantum geometry, going beyond scalar quantities such as the trace. Here we study the eigenvalue statistics of the quantum geometric tensor in finite-dimensional parameter-dependent random Hamiltonians. We obtain exact analytical results for the first two nontrivial cases, $ N=2$ and $ N=3$ , with $ N=3$ already showing genuine shape fluctuations. We further propose a finite-$ N$ , arbitrary-$ D$ description of QGT eigenvalue statistics and verify it by numerical simulations. Our results provide exact benchmarks and a practical framework for random quantum geometry in finite-dimensional disordered and chaotic systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
9 pages, 4 figures. Comments are welcome
Exceptional Points as Manifestations of Topological-Charge Breakdown in a Non-Hermitian Skyrmion
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
The integer topological charge of a magnetic skyrmion is the standard emblem of topological protection. We ask what happens to that protection when the magnet is made non-Hermitian, with balanced gain and loss or a PT-symmetric anisotropy. A non-Hermitian skyrmion turns out to carry two charges that coincide in the Hermitian limit but part ways under deformation. The charge built from the right state alone is homotopy-protected: the PT flow reduces exactly to a Gilbert-type relaxation on the target sphere, so it cannot change under smooth evolution. The charge built from the biorthogonal left-right pair is complex, loses quantization as soon as the gain/loss is turned on, and breaks down at the exceptional point of the local generator – a ring on the skyrmion’s equator, where the biorthogonal Bloch field itself diverges. Topological protection of a skyrmion is therefore not a single statement once the dynamics is non-Hermitian: it splits at an exceptional point. This is the real-space topological counterpart of the analyticity breakdown a causal response function suffers at an exceptional point, both being manifestations of the same non-Hermitian degeneracy.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Optics (physics.optics)
10 pages, 2 figures. Companion to “Exceptional Points as Manifestations of Analyticity Breakdown in the ‘t Hooft Model” (submitted to SciPost Physics). Data and code: this https URL
Universality in strongly interacting bosonic clusters
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-29 20:00 EDT
L. Madeira, F. Pederiva, U. van Kolck
We develop an effective field theory (EFT) for strongly interacting bosonic clusters, using $ ^4$ He as a paradigmatic example of universality in systems with large scattering length. At leading order (LO), two- and three-body zero-range interactions are entirely determined by the dimer and trimer ground-state energies. We show that ground-state energies for up to $ N=15$ particles converge to cutoff-independent limits with extrapolation coefficients of natural size. At next-to-leading order (NLO), corrections stemming from the two-body interaction range and a four-body force, calibrated to the tetramer ground-state energy, reduce cutoff sensitivity. Close agreement with results from a realistic potential is found at LO and improved at NLO, demonstrating systematic convergence with few parameters at each order. The resulting EFT is directly applicable to larger clusters and bulk helium.
Quantum Gases (cond-mat.quant-gas), Nuclear Theory (nucl-th), Atomic and Molecular Clusters (physics.atm-clus)
7+8 pages, 3+8 figures
Theory of Electron Spin Resonance Scanning Tunneling Microscopy: The First Decade
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Saba Taherpour, Denis Janković, Hoang-Anh Le, Jose Reina-Galvez, Christoph Wolf
Electron spin resonance in scanning tunneling microscopy enabled the study of electronic transitions of magnetic impurities on surfaces at the atomic scale. This ESR-STM technique allows to spectroscopically probe and coherently manipulate spins using an all-electrical method without oscillating external magnetic driving fields. Here, we aim to review recent advancements in ESR-STM. We will discuss possible fundamental mechanisms by which the electric field drives spin resonance based on Heisenberg exchange, Kondo scattering, and Anderson impurity models. We validate theoretical predictions against experimental observations, to understand how electronic correlations, spin exchange, and many-body effects manifest in ESR-STM signals. After reviewing coherent spin control in the STM junction, we discuss potential applications of the ESR-STM method for coherent multi-spin control which enables multiple-qubit operations. Finally, we address recent developments in coupled electron-nuclear spin systems, including hyperfine-resolved ESR spectroscopy, and the driving and polarization of nuclear spins in ESR-STM.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Rare Events Govern Defect Formation under Weak Symmetry Breaking
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
Jiang Liu, Peng Yang, Matteo Baggioli
Crossing a continuous phase transition out of equilibrium typically generates topological defects whose density obeys a universal power-law scaling predicted by the Kibble-Zurek mechanism. Recent numerical studies have revealed systematic deviations from this scaling in the presence of weak explicit symmetry breaking, manifested as an additional exponential suppression of defect formation. However, the origin of this correction and a general theoretical framework to describe it have remained elusive. Here, using large-deviation theory, we show that defect formation under weak symmetry breaking is controlled by rare fluctuations that drive local regions into the disfavored symmetry-broken state. This mechanism yields a closed-form expression for the defect density in arbitrary dimensions, valid in the weak-field and weak-noise limits. These theoretical predictions are verified through direct simulations of stochastic Ginzburg-Landau models in one and two spatial dimensions.
Statistical Mechanics (cond-mat.stat-mech)
v1: comments are welcome
Single-Crystalline Al/Ge Heterostructure with an Atomically Sharp Commensurate Interface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Jian-Huan Wang, Ding-Ming Huang, Han Gao, Yuan Yao, H. Q. Xu, Jian-Jun Zhang
A key challenge in developing Al/Ge heterostructures for quantum applications is Al-Ge interdiffusion. This process is facilitated by grain boundaries in polycrystalline films, which degrades interface quality and impairs device performance and reliability. Here, we present epitaxial growth of single-crystalline Al(111) on Ge(111) by molecular beam epitaxy, achieving an atomically flat and sharp interface. At the interface, a commensurate 7-Al-lattice/5-Ge-lattice epitaxial relationship is observed, which dramatically reduces the intrinsic lattice mismatch from 28.4% to about 0.1%. Interestingly, this well-ordered interface does not form below a critical thickness of 0.3 nm. Instead, Al initially nucleates as random clusters, which then transform into two-dimensional (2D) islands and, as Al deposition further increases, eventually develop into a continuous film. By optimizing the growth parameters, we have achieved an ultra-flat Al film with a surface root-mean-square roughness of about 0.16 nm and an ultra-thin continuous film with thickness of only 2 nm. These epitaxially grown Al-Ge heterostructures, with their atomically flat surfaces and sharp interfaces, provide a promising platform for studying topological quantum states.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantum enhancement of information-mediated energy transfer
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
Shotaro Oki, Yuki Kadono, Kaito Tojo, Takahiro Sagawa, Ken Funo
Thermodynamics of information identifies information flow as a thermodynamic resource, but whether quantum coherence and collective coupling can enhance it at low entropy-production cost remains unresolved. We address this question for interacting open quantum systems by deriving a thermodynamic uncertainty relation that bounds information flow by entropy production in nonequilibrium steady states. We construct a quantum engine in which N-fold degenerate ground and excited states are collectively coupled to heat baths. Collective jumps enhance heat currents and information flow linearly with N, while entropy production remains independent of N, realizing a high-power, low-dissipation autonomous quantum Maxwell’s demon that leverages collectively enhanced information flow to pump heat against a temperature gradient. Beyond steady states, collective interactions amplify the unitary component of quantum information flow, yielding a quadratic enhancement of the free-energy charging power of quantum batteries. Our results reveal scalable advantages of quantum coherence and collective effects in quantum engines.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
A stochastic model of a nuclear reactor with directed percolation. Overjump and maximum power
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
A stochastic risk model is applied to simulating the behavior of a nuclear reactor in a situation where the neutron chain length is described by a distribution with heavy “tails,” such as the Pareto distribution. Probabilities of a fluctuation exceeding a critical threshold are obtained, and risk bounds for power-law distributions of jumps are estimated. Functionals of the reactor power maximum, the instant of first reaching the maximum, and the distribution of the overjump magnitude are considered. A relationship between the shape parameter and the physical constants of reactors is obtained, as well as the relationship with the noise spectrum and physical constants. The finite dimensions of a real reactor are taken into account. The autocorrelation function of the truncated Lévy process and its relationship with the frequency filters of the neutron flux monitoring equipment are considered.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
23 pages, 2 figures
Unlocking Cryogenic Energy Storage by Constructing Dipole Glass with Unit-cell-level Polar Disorder
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Yangyang Si, Denan Li, Yijie Li, Changsheng Chen, Jingxuan Li, Chao Zhou, Hao Xiong, Tianfu Zhang, Wenjin Liao, Zhongqi Ren, Huaicheng Yuan, Dong Li, Jing-Kai Qin, Cheng-Yan Xu, Ye Zhu, Yunlong Tang, Sujit Das, Jieun Kim, Junling Wang, Hao Pan, Fei Li, Zhen Chen, Shi Liu, Zuhuang Chen
Cryogenic energy storage is vital for frontier technologies including deep-space exploration and quantum computing, yet conventional electrochemical energy systems fail below ~230 K due to frozen ion migration. While relaxor-based dielectric capacitors provide high efficiency at room temperature, the intrinsic freezing/growth of polar nanodomains at extended cryogenic regime limits their applications with deteriorated hysteresis losses. Here, we realize superior cryogenic energy-storage performance by designing unit-cell-level disordered dipole-glass state in Pb0.6Sr0.4ZrO3 thin films with composition near antiferroelectric-paraelectric phase boundary. The antiferroelectric-derived dipole-glass introduces enhanced unit-cell-level complexity of dipole interaction that suppresses long-range ferroelectric order. This enables ultralow-hysteresis operation (efficiency > 88%) down to 4 K, delivering record-high energy density (211 J/cm^3) at 9 MV/cm, stability over 10^8 charge/discharge cycles and microsecond-scale charge/discharge capability. This work establishes a dipole-glass paradigm for cryogenic dielectric capacitors, opening a new avenue to highly-efficient energy-storage systems with broad applications in frontier nanoelectronics.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
23 pages, 4 figures
Symmetry-Selective Strain Control of Spin-Momentum Locking and Spin Transport in Two-Dimensional Pentagonal Altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
ShuaiYu Wang, Sheng Chen, Xiao-Ping Li, Lei Wang
Altermagnets are compensated magnets featuring momentum-dependent nonrelativistic spin splitting generated by nontrivial operations connecting opposite-spin sublattices. A direct symmetry-based route to control this spin splitting is to modify the real-space operations that define the altermagnetic spin-momentum locking (SML). Here, we develop a strain-resolved symmetry framework for two-dimensional pentagonal altermagnets, classifying whether uniaxial and shear strain tensors preserve, reconstruct, or eliminate the SML. Using the above criterion combined with first-principles screening, we identify 94 stable altermagnetic candidates from 3330 materials. These candidates cover all type-III spin Laue groups of orthorhombic lattices and are classified into three strain-response types: Type-I preserves the SML; Type-II reconstructs the SML through partial symmetry breaking while retaining essential altermagnetic features; and Type-III destroys the altermagnetic SML. Representative materials further demonstrate this classification: ferroelastic $ \alpha$ -CoS$ _2$ exhibits ferroelastically switchable SML and reverses the sign of the off-diagonal spin conductivity; shear-strained (\alpha)-CoP(_2) undergoes a (g)- to (d)-wave reconstruction of the SML, activating off-diagonal spin conductivity; and uniaxially strained FeSSe realizes strain-selected spin-valley transport. This work provides theoretical and material guidance for strain-controlled transport in two-dimensional orthorhombic altermagnets.
Materials Science (cond-mat.mtrl-sci)
Metamagnetism in UTe2: the roles of itinerancy and localization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
Theodore I. Weinberger, Daniel Shaffer, Zheyu Wu, Dmitry V. Chichinadze, Jinxu Pu, Gang Li, Rui Zhou, Yurii Skourski, Dave Graf, Andrej Cabala, Vladimir Sechovsky, Michal Valiska, Michal P. Kwasigroch, F. Malte Grosche, Alexander G. Eaton
The metamagnetic transition in UTe$ _2$ plays a key role in stabilizing two enigmatic field-induced superconducting phases. One of these phases (SC2) is truncated by the transition, lying directly below it, while the other (SC3) sits predominantly above it and appears to be stabilized because of it. While numerous pulsed field studies have examined this transition, comparatively few steady field experiments have investigated it. Here we report a suite of measurements of metamgnetism in UTe$ _2$ , at ambient pressure by torque magnetometry and extraction magnetometry techniques, and of the magnetoconductance under pressure. Our steady field measurements resolve a complex sub-structure within the transition, with separate features that possess different temperature evolutions, pointing to distinct contributions from itinerant and localized moments. The itinerant contribution might relate to a possible spin-density wave state. We theoretically model the evolution of Kondo and RKKY interactions and propose that the SC2 state is stabilized under pressure due to the collapse of magnetic anisotropy, leading to an enhancement of longitudinal spin fluctuations along the hard $ b$ axis, which are pair-forming in the $ p$ -wave channel.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Open Nanoacoustic Resonators Based on SrTiO$_3$/YBa$_2$Cu$3$O${7-x}$ Superlattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
S. Sandeep, O. Colmegna, S. Carreira, L. M. Vicente-Arche, L. B. Steren, J. Briatico, N. D. Lanzillotti-Kimura
We report the design and experimental demonstration of an open nanophononic cavity based on a hybrid oxide superlattice composed of SrTiO$ _3$ (STO) and YBa$ _2$ Cu$ _3$ O$ _{7-x}$ (YBCO), combined with a metallic Ni transducer for coherent phonon generation. The STO/YBCO periodic stack acts as an acoustic distributed Bragg reflector supporting confined longitudinal acoustic phonons in the sub-THz regime, while the Ni layer enables efficient ultrafast optical excitation and detection by time-domain Brillouin scattering. Transient reflectivity measurements reveal confined acoustic dynamics and a well-defined cavity resonance, in agreement with transfer-matrix calculations of acoustic reflectivity and mode profiles. These results demonstrate phonon confinement in multifunctional oxide heterostructures and establish complex oxide superlattices as a platform for hybrid nano-acoustic resonators and ultrafast phonon control of correlated electronic phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Hidden valley dynamics behind vanishing circular polarization in moiré excitons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Yuto Urano, Lata Chouhan, Nurul Fariha Ahmad, Kenji Watanabe, Takashi Taniguchi, Daichi Kozawa, Ryo Kitaura
Optically addressable valley degrees of freedom in transition-metal dichalcogenide heterostructures provide a powerful platform for valleytronic and quantum-optical functionalities. In moiré superlattices, interlayer excitons inherit valley-contrasting optical selection rules while acquiring long lifetimes, electric dipoles, and site-dependent optical responses. However, because conventional measurements typically probe time-integrated valley polarization, the dynamical origin of vanishing polarization has remained elusive. Here, we show that a nearly zero steady-state valley polarization in electrically tunable moiré excitons does not necessarily indicate fast valley relaxation. Helicity-resolved time-resolved photoluminescence reveals a temporal crossing between co- and cross-circularly polarized emission, indicating that helicity-opposite dynamical components coexist and compensate after time integration. A minimal two-channel model, representing A-like and B-like moiré emission channels with opposite optical selection rules and distinct effective decay/depolarization rates, reproduces the observed helicity crossing without invoking a single rapid valley relaxation process. Furthermore, two-dimensional gate-field maps show that the crossing time evolves systematically with electrostatic tuning, demonstrating that the hidden valley dynamics are electrically controllable. These results show that time-integrated circular polarization can give a false-negative indication of valley polarization in multichannel valley emitters.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
A Finite Element Method for Fluctuating Navier–Stokes Equations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
Dimitrios Gourzoulidis, Mirko Gallo, Soumaya Elkantassi, Toby Kay, Serafim Kalliadasis
We introduce a finite-element framework for simulating thermal fluctuations in compressible fluids governed by the fluctuating Navier-Stokes equations. The method is designed to preserve the fundamental fluctuation-dissipation balance at the discrete level. This is achieved by defining the stochastic forcing term in the weak formulation, ensuring its covariance is proportional to the discrete viscous dissipation operator. A nodal quadrature rule is employed to eliminate unphysical mesh-scale correlations. The time integration is performed using the Crank-Nicolson scheme to maintain numerical stability and accuracy. The proposed approach is numerically validated in one, two, and three spatial dimensions, demonstrating its capability to correctly capture equilibrium fluctuation statistics across various discretisation parameters.
Statistical Mechanics (cond-mat.stat-mech), Numerical Analysis (math.NA), Fluid Dynamics (physics.flu-dyn)
Comment on “Altermagnetic and Dipolar Spitting of Magnons in FeF_2” arXiv:2601.04303
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
Conclusions by Sears et al. (arXiv: 2601.04303) about dispersions of magnons in rutile FeF_2 are unsound because compulsory lattice vibrations are omitted in the analysis of their neutron scattering spectra. Hybridized magnon-phonon modes in magnetically ordered FeF_2 were observed and successfully analysed half a century ago.
Strongly Correlated Electrons (cond-mat.str-el)
Nonextensive Statistical Signatures of the Bilaterian Transition in Proteome Length Distributions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
Protein length distributions across the tree of life carry a quantitative signature of organismal complexity. Nonextensive statistical mechanics, through the Tsallis generalized entropy formalism, provides a natural framework for describing complex systems characterized by long-range correlations, scale invariance, and hierarchical organization – features that classical Boltzmann-Gibbs statistics cannot accommodate. In this work, the complementary cumulative distribution function (CCDF) of protein lengths is analyzed within this framework for the reference proteomes of 22 fully sequenced organisms spanning the domains Archaea, Bacteria, and Eukarya, with deliberate sampling across the animal transition zone from sponges and cnidarians to higher bilaterians. Maximum likelihood (MLE) fitting of truncated discrete q-exponential distributions, with bootstrap 95% confidence intervals (CIs) reveals that the entropic index q resolves into three statistically distinct regimes: superextensive (q < 1) for prokaryotes, unicellular and non-animal multicellular eukaryotes, and basal animals; a boundary regime (CI on spanning unity) for the two cnidarians studied and the basal bilaterian C. teleta; and subextensive (q > 1) for all higher bilaterians, with q increasing monotonically across the four deuterostomes sampled from S. purpuratus (1.033) to H. sapiens (1.147). The q-exponential outperforms the ordinary exponential distribution across all 22 proteomes and becomes progressively more competitive against alternative two-parameter distributions as proteome complexity increases. These results identify the Tsallis entropic index as a continuous, physically interpretable indicator of proteome organizational complexity and extend the applicability of nonextensive statistical mechanics to proteomic systems.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
Submitted to Eur. Phys. J. E
Competing spin-1 and spin-2 regimes in a frustrated four-leg spin-1/2 ladder
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
D. S. Almeida, R. R. Montenegro-Filho
We investigate a frustrated four-leg spin-$ 1/2$ ladder using density matrix renormalization group calculations. The uniform system displays three regimes: short-range antiferromagnetic legs, short-range ferromagnetic legs, and an effective spin-2 Heisenberg chain, separated by a crossover and a first-order transition. The spin-2 regime is confirmed through its finite string order parameter, edge-localized excitations, and excellent agreement with a projected $ S_r=2$ effective Hamiltonian. Recasting the model as two frustrated two-leg ladders coupled by rung and diagonal interactions, we track how the trivial and Haldane phases of an isolated ladder evolve as interladder couplings are introduced. The resulting phase diagrams reveal crossover and first-order lines whose locations are captured by the spin-2 projection and show how singlet- and triplet-dominated regimes reorganize when two ladders merge into a four-leg structure, clarifying the emergence of effective spin-1 versus spin-2 behavior.
Strongly Correlated Electrons (cond-mat.str-el), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)
13 pages, 11 figures
Ferrimagnetic and Haldane-type phases in a mixed-spin $1$-$\tfrac{1}{2}$-$\tfrac{1}{2}$ quantum trimer chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-06-29 20:00 EDT
A. Felinto, R. R. Montenegro-Filho
Bipartite Lieb-Mattis ferrimagnetism and the symmetry-protected Haldane phase are paradigmatic mechanisms in quasi-one-dimensional quantum magnets. Both emerge, in distinct regimes, in a mixed-spin $ 1$ -$ \tfrac{1}{2}$ -$ \tfrac{1}{2}$ Heisenberg trimer chain with antiferromagnetic backbone exchange $ J$ and a side spin-$ \tfrac{1}{2}$ coupled to each backbone spin by an exchange $ J_t$ of either sign. Using the density matrix renormalization group, we compute magnetization curves and the entanglement spectrum and entropy. For $ J_t>0$ a robust ferrimagnetic plateau forms at magnetization per unit cell $ m=1$ , whose multiplet entropy reflects how the conserved magnetization splits between the halves. For $ J_t<0$ an $ m=0$ plateau opens and grows with $ |J_t|$ , while the $ m=1$ plateau closes. As $ J_t\to-\infty$ the chain maps onto a spin-$ 1$ Heisenberg chain with coupling $ J/2$ : the $ m=0$ width $ \Delta h\simeq 0.196$ matches half the Haldane gap. Exponentially localized spin-$ \tfrac{1}{2}$ edge states and the even-fold degeneracy of the entanglement spectrum confirm the Haldane character of the $ m=0$ phase.
Strongly Correlated Electrons (cond-mat.str-el)
29 pages, 12 figures
Porosity Effects on Cyclic Gas Invasion and Trapping in Deformable Porous Media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-29 20:00 EDT
Haiyi Zhong, Jieting Long, Xiangyu Ding, Zhongzheng Wang, Yixiang Gan
Fluid transport in deformable porous media is central to many biophysical and geophysical processes. While extensive studies exist, how porosity governs fluid behaviour in deformable systems during cyclic injection remains elusive. Here, we investigate gas-liquid multiphase flow in a quasi-2D Hele-Shaw cell packed with soft hydrogel particles at different initial porosities. Alternative gas and water injection experiments, combined with high-resolution imaging and continuous pressure monitoring, are used to quantify gas dynamics and pressure evolution. Results show that the gas entry pressure increases as porosity decreases, consistent with a Young-Laplace estimation based on effective pore-throat width. After entry, invasion shifts from cavity-dominated expansion in high porosity packings to localised pore invasion in low porosity packings, with a mixed cavity-fingering regime at intermediate porosity. Pressure fluctuations are linked to pore-scale gas escape and internal gas redistribution. Low porosity packings produce frequent small-amplitude pressure drops, whereas higher porosity packings produce more discrete pressure relaxations. Across cycles, the decreasing mean pressure suggests preferential-pathway reuse and reduced local capillary constraints. Residual gas saturation increases systematically with injection cycles and reaches higher terminal values as porosity decreases. Specific interfacial length increases as available pore space decreases and follows a power-law relationship with gas cluster size, with scaling exponent decreases as porosity decreases and cycling progresses. Together, these results demonstrate that gas trapping in deformable porous media depends on both initial packing structure and cyclically evolving gas-solid interactions. This study provides insights for interpreting porosity-dependent trapping and reinvasion during repeated gas injection.
Soft Condensed Matter (cond-mat.soft)
31 pages, 8 figures
Determining Electron Beam Lateral Coherence in a Scanning Electron Microscope Using Electron Diffraction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Evelijn Akerboom, Fatemeh Kiani, Giulia Tagliabue, Wiebke Albrecht, Joanne Etheridge, F. Javier García de Abajo, Albert Polman
We develop and characterize scanning transmission electron microscopy (STEM) capabilities within a scanning electron microscope (SEM) to investigate the effective lateral coherence of the electron beam (e-beam) in the specimen plane. Using single-crystalline Au flakes and a sample composed of a monolayer of graphene, we obtain high-quality selected-area electron diffraction (SAED) maps and convergent-beam electron diffraction (CBED) patterns, validating the systems ability to probe crystallographic information at an acceleration voltage of 30 keV. Building on these capabilities, we implement a method, which is adapted from techniques traditionally used in transmission electron microscopy, to measure the degree of lateral coherence of the e-beam in the specimen plane of the SEM. By analyzing interference between electrons with two different wave vectors separated by 0.031 per angstrom, we extract a lower limit for the degree of lateral coherence over 5% of the e-beam diameter of approximately 60%. These coherence values are sufficient to enable quantum-coherent electron-light-matter interaction experiments in the SEM.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Atomic and Molecular Clusters (physics.atm-clus)
14 pages, 7 figures, with appendix
In situ synchrotron X-ray diffraction study of flash austenitization and process design insights in medium-Manganese steels for energy applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Bowen Zou, Mathias Zapf, Thea Kannenberg, Daniel Schneider, Yixu Wang, Xiao Shen, Ulrich Prahl, Wenwen Song
Medium Mn steels (MMnSs) are promising candidates for energy-related infrastructure because their multiphase microstructures and austenite stability can be tailored to improve failure resistance under demanding service conditions. Flash austenitization (FA) provides a rapid route to form austenite while limiting prior austenite grain coarsening and substitutional solute homogenization, but the related short-time transformation kinetics remain insufficiently quantified. In the present work, the effects of FA temperature and initial microstructure on austenitization kinetics were investigated in an Fe-6Mn-1.5Si-1Cr-0.3Mo-0.05Nb-0.2C (wt.%) MMnS using dilatometry-integrated in situ synchrotron X-ray diffraction. Two initial microstructures produced by austenite reversion treatment (ART) were heated at 100 degrees C/s to 850 degrees C, 900 degrees C, or 950 degrees C and then held isothermally. Rapid heating alone is insufficient for full austenitization, even above the reference Ac3 temperature determined under slow heating. Full austenitization, defined by bcc fraction (f_alpha) <= 1 wt.%, requires short holding, decreasing from about 8 s at 850 degrees C to about 2 s at 950 degrees C. The final stage of austenitization is less sensitive to FA temperature than the early holding stage. The initial ART state mainly shifts the starting austenite fraction, whereas both states show comparable kinetic trends at higher FA temperatures.
Materials Science (cond-mat.mtrl-sci)
Room-temperature magnon-phonon transduction in high-damping Co/Pt structures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Gauravkumar Patel, Takuma Sato, Maximilian Frenzel, Prakriti P. Joshi, Ruslan Salikhov, Ievgeniia Korniienko, Dominik Legut, Olav Hellwig, Sebastian F. Maehrlein, Kilian Lenz, Jürgen Lindner
Quantum communication and information processing strongly benefit from the coupling between different quasi-particles, offering complementary advantages. Magnetoelastic materials inherently allow for direct coupling between magnetization dynamics and quantized lattice vibrations, called phonons. Near the ferromagnetic resonances, phonons may thus trade energy and angular momentum with uniformly precessing magnetization, called magnons, and enable transduction of information from magnetic to phononic modes, thereby paving the way for long-range transport of magnetic information without the need of magnetic material. Here, we employ tailored magnetic-nonmagnetic heterostructures, which simultaneously act as cavities for standing shear waves, to bring selective phonons and magnons into resonance. These Co films with Pt seed layers show extended linewidth and reduced amplitude of the phonon-resonant FMR lines, providing a hallmark of energy and angular momentum exchange. Complementarily, by theoretical modeling and ultra-fast coherent phonon spectroscopy, we identify the responsible transverse acoustic phonons as standing shear waves in the combined Co and Pt structure. We find a high crystal quality in conjunction with a large magnetoelastic coupling constant as a prerequisite for efficient magnon-phonon coupling of this type. Such resonant enhancement of magnon-phonon coupling in CMOS-compatible material provides an ideal material platform for future quantum transducers.
Materials Science (cond-mat.mtrl-sci)
Population-Dominated Ergotropy in a Capacitively Coupled Double-Quantum-Dot Battery under 1/f Charge Noise
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Khalil Loukhssami, Khadija El Hawary, Sanaa Abaach, Morad El Baz
We investigate extractable work storage in a capacitively coupled double quantum dot (DQD) quantum battery (QB) subjected to experimentally motivated detuning charge noise. The battery is modeled as two interacting charge qubits with an Ising-type capacitive coupling and is charged by resonant microwave modulation of the tunnel coupling channel. Detuning fluctuations are introduced as classical stochastic processes generated from a band-limited 1/f noise spectrum. For each noise realization, the evolution remains unitary, whereas decoherence and loss of contrast emerge after ensemble averaging. We analyze the total ergotropy, its population and coherent contributions, the energy basis populations, a passive ordering violation diagnostic, and the Jensen-Shannon coherence of the noise-averaged state. The results show that resonant tunnel coupling driving selects a dominant E0 <-> E3 population transfer channel in the interacting DQD spectrum. The dominant extractable work is stored in non-passive population distributions, in agreement with recent population ordering interpretations of ergotropy in QBs, while coherence accompanies and supports the resonant transfer as a transient dynamical resource. Detuning noise reduces the energy basis coherence amplitude and also weakens the population transfer pathway responsible for the dominant population ergotropy. This framework provides a noise-aware description of semiconductor QB charging based on extractable work rather than on injected energy alone.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
13 pages, 3figures,
Tuning the optoelectronic properties of wide bandgap perovskites: Data-driven insights from combinatorial synthesis and high-throughput experimentation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Alexander Wieczorek (1), Sergey Tsarev (2,3), Nathan Rodkey (1), Oleksandr Pshyk (1), Stefanie Frick (1), Maksym V. Kovalenko (2,3), Sebastian Siol (1) ((1) Laboratory for Surface Science and Coating Technologies, Empa-Swiss Federal Laboratories for Materials Science and Technology Ueberlandstrasse, Duebendorf, Switzerland. (2) Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland. (3) Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zurich, Switzerland)
The discovery and optimization of wide-bandgap lead halide perovskites (LHPs) is hindered by solution-based workflows with limited scalability. Large compositional parameter spaces present an additional challenge for materials optimization. Here, we establish an integrated, combinatorial workflow based on sequential physical vapor deposition that enables independent tuning of cation (Cs/Pb) and anion (Br/Cl) compositions. Applying automated structural, compositional, and optical characterizations across >500 samples regions of interest are rapidly screened in the quaternary Cs-Pb-Br-Cl space. From the screening, we establish a practical Cs/Pb window of 1.05-1.20 for wide bandgap perovskites, within which elevated PL yields were observed. Through in-depth analysis of the data set, we uncover a high-energy optical transition as a robust determinant for high PL yields. By combining mechanistic insight into the compositional origins of high PL efficiency with a fully integrated, high-throughput screening framework, and by openly releasing the complete multi-modal dataset, this work provides a broadly accessible benchmark to accelerate data-driven discovery of wide-bandgap perovskites.
Materials Science (cond-mat.mtrl-sci)
Phase structure of the Random Language Model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
Alessio Giorlandino, Eric De Giuli, Sebastian Goldt
Context-free grammars are minimal models of hierarchical structure in human language, generating structured text from recursive production rules. The Random Language Model (RLM) [De Giuli, PRL 2019], an ensemble of such grammars with random rule weights, exhibits a cross-over from gibberish-like output to structured text as a function of a “temperature”, but the location and nature of this transition remained unclear. Here, we show that the RLM exhibits a hierarchy of phase transitions in a double-scaling limit where the grammar temperature $ \tilde{\epsilon}_d \to 0$ and the number of hidden symbols $ N \to \infty$ at fixed $ x = \tilde{\epsilon}_d \log N$ . By identifying the relation between RLM and the Random Energy Model, we identify a series of transitions where correlations between symbols emerge, single-symbol marginals become non-uniform, and rule use freezes in a glassy phase. A semi-annealed approximation yields nontrivial scaling laws for rule usage, entropy, and energy, consistent with Heaps’ law and context-length scaling observed in large language models.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Scaling limit of the Random Language Model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
We develop a quantitative theory of the Random Language Model (RLM), an ensemble of stochastic context-free grammars, in a scaling limit where the number of hidden symbols $ N \to \infty$ while the grammar temperature $ \tilde{\epsilon}_d \to 0$ at fixed $ x = {\tilde\epsilon}_d \log N$ . In this limit, the model admits a controlled description based on a large-deviation principle over rule-usage patterns. A semi-annealed approximation maps the problem to a class of Random Energy Models with nontrivial combinatorics.
We show that the RLM exhibits a condensation transition at a critical value $ x_c=1/8$ , below which rule usage concentrates and language statistics acquire a nontrivial dependence on corpus length. A second characteristic scale at $ x=1/2$ marks the onset of entropy reduction from its maximal value. Across these regimes, we derive explicit scaling laws for the number of distinct rules, entropy, and related observables, identifying distinct scaling, saturation, and critical regimes controlled by the interplay of grammar size, corpus length, and temperature.
The theory resolves previous ambiguities regarding the existence of a thermodynamic transition and explains the slow approach to the large-$ N$ limit as a consequence of the dependence on $ \log N$ . It further provides a unified framework in which universal statistical properties of language emerge from typical realizations of generative grammars, with implications for both natural language statistics and the behavior of large language models.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Computation and Language (cs.CL)
17 pages + 14 pages SI
Uniaxial compression of crystalline HCP titanium: an atomistic modelling study of size effects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Fatemeh Safari, Konstantinos Konstantinou
Understanding the deformation behaviour of titanium is important not only for technological advances associated with industrially-relevant applications, but also essential to achieve a fundamental understanding of the mechanical properties of the relevant alloys. In this computational study, molecular-dynamics simulations are employed to ascertain the impact of model size on the mechanical response of alpha-titanium under compression. The deformation behaviour of the crystalline models is investigated as a function of different system sizes (varied by four orders of magnitude, up to 32 million atoms), and strain rates (down to 10^8 s^-1). The results show that the elastic properties remain independent of both system size and strain rate, whereas marked size effects emerge during plastic deformation. Increasing the system size of the titanium model reduces stress fluctuations, results in more homogeneous structural evolution, and stabilizes dislocation activity. Decreasing the applied strain rate requires correspondingly a larger system size to achieve equilibration and to ensure a stable behaviour for the simulated structure. The modelling results demonstrate that system size and strain rate are strongly coupled, and their combined effect governs the simulated deformation behaviour of the compressed crystalline material.
Materials Science (cond-mat.mtrl-sci)
Universality of Bubble Coalescence in Electrolytic Media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-29 20:00 EDT
Afsal Chakkam Palliyalil, Gaurav Tomar, Susmita Dash
Bubble coalescence phenomenon in electrolytic media finds applications in technologies from mineral flotation to electrochemical energy conversion. However, the underlying governing physics still remains unresolved, with longstanding disagreement over the extent to which Marangoni stresses affect the coalescence time by modulating the interfacial mobility. Here, we show that the thin film morphology governs drainage more strongly than the interfacial boundary conditions. We demonstrate experimentally that thin film drainage during bubble coalescence proceeds through three distinct regimes. An initial visco-capillary stage that exhibits a power-law thinning, followed by an exponential decrease in film thickness with time induced by rim stabilisation. The final regime is governed by disjoining pressure and is marked by an exponential relaxation of the film to the equilibrium thickness. We show that, irrespective of the electrolyte type and concentration, film evolution exhibits universal behavior by collapsing onto a single curve when rescaled with the characteristic film thickness and time scale, demonstrating that electrolyte effects act only to renormalize timescales rather than alter the underlying dynamics.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Moiré Phonons and Emergent Exciton-Phonon Coupling in a Moiré Heterobilayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-06-29 20:00 EDT
Can B. Uzundal, Woochang Kim, Zhiyuan Cui, Yuxuan Wei, Zheyu Lu, Qixin Feng, Francis L. Hong, Indrajit Maity, Takashi Taniguchi, Kenji Watanabe, Manish Jain, Mit H. Naik, Yoseob Yoon, Michael F. Crommie, Steven G. Louie, Feng Wang
Moiré superlattices have emerged as a new platform for engineering electronic and optical properties in van der Waals heterostructures, enabling control over correlated and excitonic phenomena. Yet the impact of moiré superlattices on exciton-phonon coupling remains largely unexplored. Here we demonstrate emergent, layer-selective coupling between moiré phonons and moiré excitons in angle-aligned WS2/WSe2 heterobilayers. Using a broadband terahertz phonon transducer, we coherently launch moiré phonons that resonantly perturb the excitonic states. We show that the exciton-phonon coupling is intrinsically modified by the moiré superlattice in a layer-selective manner. A driven oscillator model captures the dynamics, revealing three moiré phonon resonances with distinct coupling to the moiré excitons. First principles calculations show that many moiré phonon modes can arise with distinct strongly hybridized in-plane and out-of-plane vibrations in the moiré unit cells. The calculations further identify the three experimentally observed moiré phonons and their emergent characteristic coupling to the moiré excitons.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Imaging geometry- and phase-controlled spectra in a surface-state Andreev cavity
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-29 20:00 EDT
Adrian Greichgauer, Yoichi Ando, Jens Brede
Andreev cavities provide a setting in which superconducting proximity spectra are shaped by phase-coherent electron-hole motion along extended trajectories. While such Andreev physics is well established in transport, local spectra in two-dimensional cavities remain largely unexplored in real space. Here we use scanning tunnelling spectroscopy to study confined Cu(111) surface states coupled to superconducting Nb(110). The in-plane magnetic-field scale for the collapse of the resolved low-energy spectrum is controlled by the transverse extent available to Andreev trajectories, while the zero-field excitation energy evolves with the characteristic trajectory length. These trends, together with spatial variations within individual islands and the response to vortex phase textures, are captured by a minimal semiclassical phase-accumulation picture. Our results identify geometry-defined Andreev trajectories as a design principle for phase-coherent superconducting cavities accessible by local spectroscopy.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12-page manuscript with 7 main/extended-data figures and 19-page Supplementary Information with 11 supplementary figures
Role of the Casimir force in the capacitive radio-frequency microelectromechanical switches
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
G. L. Klimchitskaya, A. S. Korotkov, V. V. Loboda, V. M. Mostepanenko
We determine the role of the fluctuation-induced Casimir force acting between a membrane of cylindrical shape and a bottom electrode in microelectromechanical capacitive switches. For this purpose, the Casimir force is computed taking into account the real properties of both a membrane and a bottom electrode materials with account of surface roughness. The obtained results are compared with those found for the smooth surfaces using the idealization of ideal metal. It is shown that an account of both the real material properties and surface roughness is crucial for obtaining the correct values of the Casimir force. According to our results, at the shortest separations, when the switch membrane is in contact with the transmission line, the magnitudes of the Casimir force may exceed the magnitudes of the electric one depending on the value of the operating voltage. The obtained values of the Casimir force can be used for determining the thickness of the switch membrane, which ensures the necessary magnitude of the restoring elastic force required for a stable cyclic functioning of the micromechanical switch with no pull-in.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
12 pages, 5 figures
J. Chem. Phys. v.164, 224707 (2026). J. Chem Phys. v.164, 224707 (2026)
Interlayer electric multipole Hall effect in twisted multilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-06-29 20:00 EDT
Chengxin Xiao, Cong Xiao, Dawei Zhai, Wang Yao
Electrons in layered van der Waals materials possess a layer pseudospin characterizing their wave-function distribution among layers. In twisted structures, this pseudospin forms nontrivial textures, leading to intriguing phenomena such as the layer Hall effect (LHE), where distinct layer Hall currents flow despite the presence of time-reversal symmetry. In chiral bilayers, LHE manifests as an interlayer electric dipole Hall effect with Hall counterflows and a concomitant in-plane magnetic dipole. Multilayers host richer layer-dependent Hall currents, generating interlayer electric multipole Hall effects and in-plane magnetic multipoles. We start from exploring the interlayer electric quadrupole Hall effect in mirror-symmetric twisted trilayers. At small twist angles, interlayer translation efficiently tunes layer Hall current magnitudes. At large angles and low doping, the currents can be well accounted for by adding the contributions from the two individual twisted interfaces. This decomposition allows obtaining layer-resolved Hall currents in large-angle twisted multilayers even without well-defined periodicity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Coexisting Regular and Chaotic Dynamics in the Dysprosium Feshbach Spectrum
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-06-29 20:00 EDT
Julie Veschambre, Alexandre Journeaux, Maxime Lecomte, Alice Belmon, Ethan Uzan, Inès de Verdelhan, Patricia Christina Marques Castilho, Jakub Zakrzewski, Jean Dalibard, Raphael Lopes
Strongly dipolar gases, such as dysprosium, erbium and thulium, exhibit dense Feshbach spectra whose level statistics have been associated with quantum chaos arising from couplings among many molecular channels. Here, we combine a precise calibration of the Feshbach spectrum of $ ^{162}$ Dy with spectroscopic measurements of the differential magnetic moments of bound states associated with more than 80 resonances between 0 and 30 G. These magnetic moments provide an eigenstate-sensitive probe of the molecular states underlying the resonance spectrum. We find that the level statistics are not uniform: resonances associated with states near the center of the magnetic-moment distribution display enhanced level repulsion, whereas those near the lower edge remain close to Poisson statistics. Our results reveal hidden structure within the chaotic dysprosium Feshbach spectrum and identify molecular-state composition as a key ingredient in the emergence of quantum chaos in strongly dipolar scattering.
Quantum Gases (cond-mat.quant-gas), Chaotic Dynamics (nlin.CD), Atomic Physics (physics.atom-ph)
9 pages, 5 figures
Entropy density functional theory for inhomogeneous fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-06-29 20:00 EDT
We present an exact variational scheme for the physics of inhomogeneous classical fluids in thermal equilibrium. A joint metadensity minimization principle is proven for the one-body density and the global interparticle distance distribution. The theory bypasses the inhomogeneous two-body density and thus remains computationally simple. A universal excess entropy functional accounts for all many-body correlations in arbitrary pairwise interacting systems. The framework is relevant for neural functional machine learning, for soft matter design, and for predicting structural correlation functions via entropic test-particle and meta-Ornstein-Zernike routes.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Classical versus quantum Anderson localization in disordered systems
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
Stefano Mossa, Giancarlo Ruocco, Walter Schirmacher
We investigate Anderson localization in three-dimensional disordered systems by comparing scalar classical waves with mass and force-constant disorder to electronic tight-binding models with diagonal and off-diagonal disorder. We show that the commonly employed mapping between classical-wave localization and the electronic Anderson model with diagonal disorder is not mathematically justified. Instead, the correct modulus-type formulation reveals that classical-wave systems constitute a distinct constrained disorder class, in which the acoustic sum rule correlates diagonal and off-diagonal matrix elements and prevents any direct correspondence with the standard electronic disorder models. Within a unified eigenvalue framework, we determine localization phase diagrams for all four disorder classes using complementary spectral, eigenvector, and level-statistics diagnostics. We find that classical-wave systems share a key qualitative feature with electronic off-diagonal disorder: localized states occur only near a band edge, while extended states persist in the central part of the spectrum even at strong disorder. At the same time, the acoustic sum rule produces localization topologies that differ fundamentally from both diagonal- and off-diagonal-disorder electronic systems. In particular, for mass disorder we obtain a phase diagram that differs qualitatively from previous results based on the conventional potential-type approach and reveals an extended localized regime near the upper band edge. Our results establish a unified perspective on localization in quantum and classical wave systems and provide new insight into the conditions under which Anderson localization may occur in three-dimensional photonic and acoustic media.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Optimal parameterization of nonequilibrium generalized master equations from discrete-time experimental data
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-06-29 20:00 EDT
Chih-Wei Joshua Liu, Jérémie Klinger, Grant M. Rotskoff
Kinetic analyses of experiments often require coarse-grained descriptions, but complex systems rarely conform to the widely used modeling assumptions of Markovianity and thermodynamic equilibrium. Memory is indeed a general and often inevitable consequence of coarse-graining. Markov state models (MSMs) are a popular choice of coarse-grained description, but require microstate assignments – which are rarely experimentally tunable – to macrostates that minimize memory. Generalized master equations (GMEs) circumvent this limitation of MSMs by explicitly capturing memory. However, GMEs are difficult to parameterize and usually formally approximate in the experimentally relevant discrete-time setting. Here we introduce a maximum-likelihood-based procedure to parameterize formally exact, physically feasible, discrete-time generalized master equations from experiments and simulations in and out of equilibrium. By adapting algorithms typically used in optimal transport, we construct physical-constraint-satisfying conditional-maximum-likelihood estimators of both exact Nakajima-Zwanzig memory kernels and time-convolutionless GME propagators in discrete time. Applying these estimators to three examples – experimental recordings of Förster-resonance energy-transfer in an ion channel, experimental nanoparticle tracking of a processive molecular motor, and simulated folding of a benchmark protein domain – we recover kinetic parameters including relaxation rates, irreversibilities, dwell times, and first-passage times. These results establish discrete-time GMEs as a physically and statistically principled alternative to MSMs for kinetic analyses of experimental and simulated biomolecular systems.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Chemical Physics (physics.chem-ph)
26 pages, 5 figures
Stationary point complexity via minimal supersymmetry breaking
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-06-29 20:00 EDT
The statistics of stationary points are a powerful way to understand mean-field random landscapes, and the Kac–Rice formula is a general way to compute them. A longstanding technical barrier to these calculations is the presence of the absolute value of the determinant of the Hessian. Neglecting the absolute value produces an elegant 2-index supersymmetric representation of the problem, but is often incorrect. We develop an expanded 4-index supersymmetric representation of the complexity problem which incorporates the absolute value naturally via spontaneous supersymmetry breaking along a particular superspace direction. Positing that no additional symmetry breaking occurs implies the reduction to five order parameters corresponding to elements of a superspace operator algebra generated by the spontaneously SUSY-breaking operator. We relate the order parameters to the geometry and spectra of stationary points, showing that the SUSY-breaking order parameter corresponds to the spectral density of the Hessian at zero eigenvalue. We give examples of this formalism applied to calculate the annealed complexity of several models, including the perceptron and the Sherrington–Kirkpatrick model. The framework is naturally extended to quenched complexity, where each order parameter corresponds to a replica matrix.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Excitation of Collective Modes in a Chiral Superfluid by Thermal Quench
New Submission | Superconductivity (cond-mat.supr-con) | 2026-06-29 20:00 EDT
Based on time-dependent Ginzburg-Landau field theory we show that rapid cooling through the second-order phase transition into superfluid \Hea\ excites collective modes of newly formed chiral domains, in addition to topological defects that are formed via the Kibble-Zurek mechanism. Simulations of temperature quenches in the presence of Gaussian space-time white noise generate a highly excited inhomogeneous condensate. Large-scale simulations exhibit a complex network of domain walls and vortices. We report results for the excitation of bosonic collective modes by thermal noise as well as nonequilibrium temperature quenches, followed by coarsening dynamics tracked in terms of the Fourier components of the order parameter amplitudes. For thermal states, the spectrum of bosonic excitations is defined by a power spectral density (PSD) for each mode, which is sensitive to the Langevin damping. For weak damping the PSD onsets sharply at the frequency corresponding to the mass of the bosonic mode, then decays as $ 1/\omega$ . We also track the dynamics of the order parameter following a temperature quench. We report results for the scaling exponents of Kibble-Zurek freeze-out time and correlation length as a function of quench rate for several damping rates. The dynamical exponent $ z$ is shown to transition smoothly from $ z=1$ to $ z=2$ as the damping is increased, while the correlation length exponent, $ \nu\approx 1/2$ , is independent of damping.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 6 figures