CMP Journal 2025-04-14
Statistics
Nature: 1
Nature Physics: 3
arXiv: 72
Nature
Prdm16-dependent antigen-presenting cells induce tolerance to gut antigens
Original Paper | Dendritic cells | 2025-04-13 20:00 EDT
Liuhui Fu, Rabi Upadhyay, Maria Pokrovskii, Francis M. Chen, Gabriela Romero-Meza, Adam Griesemer, Dan R. Littman
The gastrointestinal tract is continuously exposed to foreign antigens in food and commensal microbes with potential to induce adaptive immune responses. Peripherally induced T regulatory (pTreg) cells are essential for mitigating inflammatory responses to these agents1-4. While RORγt+ antigen-presenting cells (RORγt-APCs) were shown to program gut microbiota-specific pTreg5-7, their definition remains incomplete, and the APC responsible for food tolerance has remained elusive. Here, we identify an APC subset required for differentiation of both food- and microbiota-specific pTreg cells and for establishment of oral tolerance. Development and function of these APCs require expression of the transcription factors Prdm16 and RORγt, as well as a unique Rorc(t) cis-regulatory element. Gene expression, chromatin accessibility, and surface marker analysis establish the pTreg-inducing APCs as myeloid in origin, distinct from ILC3, and sharing epigenetic profiles with classical dendritic cells (cDC), and designate them Prdm16+ RORγt+ tolerizing DC (tolDC). Upon genetic perturbation of tolDC, we observe a substantial increase in food antigen-specific T helper 2 (Th2) cells in lieu of pTreg, leading to compromised tolerance in mouse models of asthma and food allergy. Single-cell analyses of freshly resected mesenteric lymph nodes from a human organ donor, as well as multiple specimens of human intestine and tonsil, reveal candidate tolDC with co-expression of PRDM16 and RORC and an extensive transcriptome shared with mice, highlighting an evolutionarily conserved role across species. Our findings suggest that a better understanding of how tolDC develop and how they regulate T cell responses to food and microbial antigens could offer new insights into developing therapeutic strategies for autoimmune and allergic diseases as well as organ transplant tolerance.
Dendritic cells, Inflammation, Mucosal immunology, Regulatory T cells
Nature Physics
Ultrafast room-temperature valley manipulation in silicon and diamond
Original Paper | Electronic properties and materials | 2025-04-13 20:00 EDT
Adam Gindl, Martin Čmel, František Trojánek, Petr Malý, Martin Kozák
Some semiconductors have more than one degenerate minimum of the conduction band in their band structure. These minima–known as valleys–can be used for storing and processing information, if it is possible to generate a difference in their electron populations. However, to compete with conventional electronics, it is necessary to develop universal and fast methods for controlling and reading the valley quantum number of the electrons. Even though selective optical manipulation of electron populations in inequivalent valleys has been demonstrated in two-dimensional crystals with broken time-reversal symmetry, such control is highly desired in many technologically important semiconductor materials, including silicon and diamond. We demonstrate an ultrafast technique for the generation and read-out of a valley-polarized population of electrons in bulk semiconductors on subpicosecond timescales. The principle is based on the unidirectional intervalley scattering of electrons accelerated by an oscillating electric field of linearly polarized infrared femtosecond pulses. Our results are an advance in the development of potential room-temperature valleytronic devices operating at terahertz frequencies and compatible with contemporary silicon-based technology.
Electronic properties and materials, Ultrafast photonics
Observation of antiferromagnetic order in a quasicrystal
Original Paper | Magnetic properties and materials | 2025-04-13 20:00 EDT
R. Tamura, T. Abe, S. Yoshida, Y. Shimozaki, S. Suzuki, A. Ishikawa, F. Labib, M. Avdeev, K. Kinjo, K. Nawa, T. J. Sato
Quasicrystals are long-range-ordered materials with atypical rotational symmetries, such as 5-fold, 10-fold or 12-fold symmetries, which are incompatible with crystallographic periodicity. Although spin-glass-like freezing phenomena have been observed in quasicrystals, antiferromagnetic order has not. Here we report experimental evidence for antiferromagnetic order in the icosahedral quasicrystal Au56In28.5Eu15.5. Its magnetization curve shows a sharp cusp at a Néel temperature of 6.5 K, and both metamagnetic anomaly below and specific heat anomaly at this temperature are consistent with an antiferromagnetic transition. The appearance of magnetic Bragg reflections in the neutron diffraction data below the Néel temperature further confirms the long-range antiferromagnetic order in this icosahedral quasicrystal. Our discovery resolves the long-standing issue of whether antiferromagnetic order is possible in real quasicrystals, inviting further studies particularly on antiferromagnetic icosahedral quasicrystals and quasiperiodic magnetic order, as opposed to periodic magnetic order generally in condensed-matter physics.
Magnetic properties and materials
Concurrent slow and fast frictional ruptures in laboratory earthquakes
Original Paper | Mechanical properties | 2025-04-13 20:00 EDT
Songlin Shi, Jay Fineberg
Frictional motion is initiated by interface failure that is mediated by ruptures–akin to earthquakes–that typically accelerate to near-sonic velocities. However, slow ruptures may occur in both laboratory and natural fault settings, but the mechanisms that drive them are not fully understood. Although fracture mechanics describes fast frictional ruptures well, its relevance to slow ruptures is uncertain. Here we experimentally show that both extremely slow and fast ruptures–on scales of cm s-1 and km s-1, respectively–can repeatably propagate within the same frictional interface. We demonstrate that a dynamic equilibrium between the loading rates and velocity dependencies of both interface resistance and fracture energy enables slow ruptures to nucleate and propagate at very low applied shear stresses. In the same interfaces, fast ruptures also occur, but only when their nucleation becomes possible under higher stress conditions. We find that the dynamics and structure of both rupture classes are well described by fracture mechanics. Their existence results from a close interplay between the interface properties and rupture velocity. These results provide key insights into fault dynamics and related frictional motion.
Mechanical properties, Nonlinear phenomena, Surfaces, interfaces and thin films
arXiv
Volatile and Nonvolatile Resistive Switching in Lateral 2D Molybdenum Disulfide-Based Memristive Devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Sofía Cruces, Mohit D. Ganeriwala, Jimin Lee, Ke Ran, Janghyun Jo, Lukas Völkel, Dennis Braun, Bárbara Canto, Enrique G. Marín, Holger Kalisch, Michael Heuken, Andrei Vescan, Rafal Dunin-Borkowski, Joachim Mayer, Andrés Godoy, Alwin Daus, Max C. Lemme
Developing electronic devices capable of emulating biological functions is essential for advancing brain-inspired computation paradigms such as neuromorphic computing. In recent years, two-dimensional materials have emerged as promising candidates for neuromorphic electronic devices. This work addresses the coexistence of volatile and nonvolatile resistive switching in lateral memristors based on molybdenum disulfide with silver as the active electrode. The fabricated devices exhibited switching voltages of ~0.16 V and ~0.52 V for volatile and nonvolatile operation, respectively, under direct-current measurements. They also displayed the essential synaptic functions of paired-pulse facilitation and short- and long-term plasticity under pulse stimulation. The operation mechanism was investigated by in-situ transmission electron microscopy, which showed lateral migration of silver ions along the molybdenum disulfide between electrodes. Based on the experimental data, a macroscopic semi-classical electron transport model was used to reproduce the current-voltage characteristics and support the proposed underlying switching mechanisms.
Materials Science (cond-mat.mtrl-sci)
36 pages
Unraveling the dynamics of conductive filaments in MoS${_2}$ based memristors by operando transmission electron microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Ke Ran, Janghyun Jo, Sofía Cruces, Zhenxing Wang, Rafal E. Dunin-Borkowski, Joachim Mayer, Max C. Lemme
Advanced operando transmission electron microscopy (TEM) techniques enable the observation of nanoscale phenomena in electrical devices during operation. They can be used to study the switching mechanisms in two-dimensional (2D) materials-based memristive devices, which is crucial to tailor their operating regimes and improve reliability and variability. Here, we investigate lateral memristive devices composed of 2D layered molybdenum disulfide (MoS$ {_2}$ ) with palladium (Pd) and silver (Ag) electrodes. We visualized the formation and migration of Ag conductive filaments (CFs) between the two electrodes under external bias voltage and their complete dissolution upon reversing the bias voltage polarity. The CFs exhibited a wide range of sizes, ranging from several Ångströms to tens of nanometers, and followed diverse pathways: along the MoS$ {_2}$ surfaces, within the van der Waals gap between MoS$ {_2}$ layers, and through the spacing between MoS$ {_2}$ bundles. Notably, the Ag electrode functioned as a reservoir for the CFs, as evidenced by the shrinking and growing of the Ag electrode upon switching. Our method enabled correlating the current-voltage responses with real-time TEM imaging, offering insights into failed and anomalous switching behavior, and providing clarity on the cycle-to-cycle variabilities. Our findings provide solid evidence for the electrochemical metallization mechanism, elucidate the formation dynamics of CFs, and reveal key parameters influencing the switching performance. Our approach can be extended to investigate similar memristive devices.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
41 pages
Exchange interactions in itinerant magnets: the effects of local particle-hole irreducible vertex corrections and SU(2) symmetry of Hund interaction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
We study exchange interactions in iron and nickel within the DFT+DMFT approach with density-density and SU(2) symmetric Coulomb interaction. In particular, we analyze the representation of exchange interactions through the non-local part of the particle-hole bubble, supplemented by the local particle-hole (ph) irreducible interaction vertices. The neglect of the local ph-irreducible vertex corrections, suggested previously within the dual fermion approach [E. A. Stepanov, this http URL., Phys. Rev. Lett. 121, 037204 (2018)], yields the result, corresponding to generalization of the magnetic force theorem approach. While we argue that these vertex corrections are not important for strong localized magnets, such as iron, they become more essential for weak itinerant magnets, such as nickel. At the same time, the account of the full local vertex and self-energy corrections in the renormalized approach is essential for iron, and less important for nickel. The difference of the results of density-density and SU(2) symmetric Coulomb interaction is found relatively small, in contrast to the Curie temperature and the value of the local magnetic moment.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
10 pages, 6 figures
Exciton fractional Chern insulators in moiré heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Raul Perea-Causin, Hui Liu, Emil J. Bergholtz
Moiré materials have emerged as a powerful platform for exploring exotic quantum phases. While recent experiments have unveiled fractional Chern insulators exhibiting the fractional quantum anomalous Hall effect based on electrons or holes, the exploration of analogous many-body states with bosonic constituents remains largely uncharted. In this work, we predict the emergence of bosonic fractional Chern insulators arising from long-lived excitons in a moiré superlattice formed by twisted bilayer WSe$ _2$ stacked on monolayer MoSe$ _2$ . Performing exact diagonalization on the exciton flat Chern band present in this structure, we establish the existence of Abelian and non-Abelian phases at band filling $ \frac{1}{2}$ and $ 1$ , respectively, through multiple robust signatures including ground-state degeneracy, spectral flow, many-body Chern number, and particle-cut entanglement spectrum. The obtained energy gap of $ \sim 10$ meV for the Abelian states suggests a remarkably high stability of this phase. Our findings not only introduce a highly tunable and experimentally accessible platform for investigating bosonic fractional Chern insulators but also open a new pathway for realizing non-Abelian anyons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Influence of the particle morphology on the spray characteristics in low-pressure cold gas process
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Y. Sinnwell, A. Maksakov, S. Palis, S. Antonyuk
This study investigates the influence of particle morphology on spray characteristics in low-pressure cold gas spraying (LPCGS) by analyzing three copper powders with distinct shapes and microstructures. A comprehensive morphology analysis was conducted using both 2D and 3D imaging techniques. Light microscopy combined with image processing quantified particle circularity in 2D projections, while X-ray micro-computed tomography (micro-CT) enabled precise 3D reconstructions to determine sphericity, surface area, and volume distributions. The results showed significant variations in the particle morphology of the investigated feedstock copper powders, with irregularly shaped particles exhibiting lower circularity and sphericity compared to more spherical feedstocks. These morphological differences had a direct impact on the particle velocity distributions and spatial dispersion within the spray jet, as measured by high-speed particle image velocimetry. Irregular particles experienced stronger acceleration and exhibited a more focused spray dispersion, whereas spherical particles reached lower maximum velocities and showed a wider dispersion in the jet. These findings highlight the critical role of particle morphology in optimization of cold spray processes for advanced coating and additive manufacturing applications.
Soft Condensed Matter (cond-mat.soft), Image and Video Processing (eess.IV), Fluid Dynamics (physics.flu-dyn)
A machine learning approach to fast thermal equilibration
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Diego Rengifo, Gabriel Tellez, Gabriel Téllez
We present a method to design driving protocols that achieve fast thermal equilibration of a system of interest using techniques inspired by machine learning training algorithms. For example, consider a Brownian particle manipulated by optical tweezers. The force on the particle can be controlled and adjusted over time, resulting in a driving protocol that transitions the particle from an initial state to a final state. Once the driving protocol has been completed, the system requires additional time to relax to thermal equilibrium. Designing driving protocols that bypass the relaxation period is of interest so that, at the end of the protocol, the system is either in thermal equilibrium or very close to it. Several studies have addressed this problem through reverse engineering methods, which involve prescribing a specific evolution for the probability density function of the system and then deducing the corresponding form of the driving protocol potential. Here, we propose a new method that can be applied to more complex systems where reverse engineering is not feasible. We simulate the evolution of a large ensemble of trajectories while tracking the gradients with respect to a parametrization of the driving protocol. The final probability density function is compared to the target equilibrium one. Using machine learning libraries, the gradients are computed via backpropagation and the protocol is iteratively adjusted until the optimal protocol is achieved. We demonstrate the effectiveness of our approach with several examples.
Statistical Mechanics (cond-mat.stat-mech)
Ultrafast dynamics of ferroelectric polarization of NbOI$_{2}$ captured with femtosecond electron diffraction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Yibo Wang, Md Sazzad Hossain, Tianlin Li, Yanwei Xiong, Cuong Le, Jesse Kuebler, Nina Raghavan, Lucia Fernandez-Ballester, Xia Hong, Alexander Sinitskii, Martin Centurion
Two-dimensional (2D) ferroelectric materials like NbOI$ _{2}$ have garnered significant interest, yet their temporal response and synergetic interaction with light remain underexplored. Previous studies on the polarization of oxide ferroelectrics have relied on time-resolved optical second harmonic generation or ultrafast X-ray scattering. Here, we probe the laser-induced polarization dynamics of 2D NbOI$ _{2}$ nanocrystals using ultrafast transmission electron diffraction and deflectometry. The deflection of the electron pulses is directly sensitive to the changes in the polarization, while the diffraction signal captures the structural evolution. Excited with a UV laser pulse, the polarization of NbOI$ _{2}$ is initially suppressed for two picoseconds, then it recovers and overshoots, leading to a transiently enhanced polarization persisting for over 200 ps. This recovery coincides with coherent acoustic phonon generation, triggering a piezoresponse in the NbOI$ _{2}$ nanocrystals. Our results offer a new method for sensing the ferroelectric order parameter in femtosecond time scales.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
26 pages, 9 figures
Fringe around a Beet Slice: Wetting-induced Dimple in a Thin Liquid Film
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Zhengyang Liu, Kunal Kumar, Yicong Fu, Abhradeep Maitra, Justin Chen, Sunghwan Jung
When a slice of beet is placed on a plate with a thin layer of beet juice, one can observe a clear fringe around the beet, where the color is more translucent than the rest of the juice. The hypotheses in literature were inconsistent and limited, which motivated us to revisit this phenomenon. Using a motorized confocal displacement sensor, we measured the temporal evolution of the liquid surface profile across the fringe. Our findings suggest that a suction flow, induced by the capillary rise of the contact line, causes a dimple - a small concave depression - to form on the liquid surface. While surface tension and gravity tends to smooth out the dimple, viscous drag acts against them if the liquid film is sufficiently thin. Our scaling analysis correctly estimates the dependence of dimple lifetime on liquid properties and film thickness. We also capture the dimple formation dynamics by numerically solving the lubrication equation with the Young-Laplace equation. This work provides a new interpretation for a common phenomenon.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Band gap tuning by structural phase transition in Sm-substituted BiFeO3 powders
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Christina Hill, Michele Melchiorre, Cosme Milesi-Brault, Pascale Gemeiner, Fabienne Karolak, Christine Bogicevic, Brahim Dkhil, Ingrid Canero-Infante, Mael Guennou
The substitution of bismuth by samarium in BiFeO3 is known to induce a structural phase transition from the polar phase to a non-polar phase, with a possible antiferroelectric intermediate structure. In this paper, we investigate the impact of this phase change on the optical properties. The optical band gap was measured by diffuse reflectance as a function of temperature for several samarium concentrations across the structural phase transition. We found that the optical band gap for each of the pure phases varies linearly with temperature and that the phase transitions are revealed by smooth transitions between those linear regimes. This allows us to quantify the contribution of the structural change in the optical absorption. We find that a difference in optical band gap of about 130meV can be attributed to the phase change. We anticipate that the same change could be obtained by applying an electric field in an antiferroelectric composition.
Materials Science (cond-mat.mtrl-sci)
8 pages, 4 figures, supplementary information
Spin Qubit Properties of the Boron-Vacancy/Carbon Defect in the Two-Dimensional Hexagonal Boron Nitride
New Submission | Other Condensed Matter (cond-mat.other) | 2025-04-14 20:00 EDT
Sergey Stolbov, Marisol Alcántara Ortigoza
Spin qubit defects in two-dimensional materials have a number of advantages over those in three-dimensional hosts including simpler technologies for the defect creation and control, as well as qubit accessibility. In this work, we select the VBCB defect in the hexagonal boron nitride (hBN) as a possible optically controllable spin qubit and explain its triplet ground state and neutrality. In this defect a boron vacancy is combined with a carbon dopant substituting the closest boron atom to the vacancy. Our density-functional-theory calculations confirmed that the system has dynamically stable spin triplet and singlet ground states. As revealed from our linear response GW calculations, the spin-sensitive electronic states are localized around the three undercoordinated N atoms and make local peaks in the density of electronic states within the bandgap. Using the triplet and singlet ground state energies, as well as the energies of the optically excited states, obtained from solution to the Bethe-Salpeter equation, we construct the spin-polarization cycle, which is found to be favorable for the spin qubit initialization. The calculated zero-field splitting parameters ensure that the splitting energy between the spin projections in the triplet ground state is comparable to that of the known spin qubits. We thus propose the VBCB defect in hBN as a promising spin qubit.
Other Condensed Matter (cond-mat.other)
12 pages, 7 figures
Two-dimensional perovskites with maximum symmetry enable exciton diffusion length exceeding 2 micrometers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Jin Hou, Jared Fletcher, Siedah J. Hall, Hao Zhang, Marios Zacharias, George Volonakis, Claire Welton, Faiz Mandani, Isaac Metcalf, Shuo Sun, Bo Zhang, Yinsheng Guo, G. N. Manjunatha Reddy, Claudine Katan, Jacky Even, Matthew Y. Sfeir, Mercouri G. Kanatzidis, Aditya D. Mohite
Realizing semiconductors with high symmetry of their crystallographic structures has been a virtue of inorganic materials and has resulted in novel physical behaviors. In contrast, hybrid (organic and inorganic) crystals such as two-dimensional metal halide perovskites exhibit much lower crystal symmetry due to in-plane or out of plane octahedral distortions. Despite their amazing ability for photoinduced light emission at room temperature, the Achilles’ heel of this attractive class of 2D materials for optoelectronics remains the poor control and lack of performance for charge carrier transport. Inspired by the tremendous charge carrier properties of the 3D cubic perovskite phase of FAPbI3 and combining the use of the appropriate cage cation, the spacer molecule and the temperature and rate of crystallization, we report a new series of FA-based layered two-dimensional perovskites that exhibits the highest theoretically predicted symmetry with a tetragonal P4/mmm space group, resulting in no octahedral distortion in both in-plane and out-of-plane directions. These 2D perovskites present the shortest interlayer distances (4 angstrom), which results in systematically lower bandgaps (1.7 to 1.8 eV). Finally, the absence of octahedral distortions, results in an exciton diffusion length of 2.5 {\mu}m, and a diffusivity of 4.4 cm2s-1, both of which are an order of magnitude larger compared to previously reported 2D perovskites and on par with monolayer transition metal dichalcogenides.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Normal state and superconducting state properties of high entropy Ta0.2Nb0.2V0.2Ti0.2X0.2 (X = Zr and Hf )
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-14 20:00 EDT
Nikita Sharma, J. Link, Kuldeep Kargeti, Neha Sharma, I. Heinmaa, S. K. Panda, R. Stern, Tirthankar Chakraborty, Tanmoy Chakrabarty, Sourav Marik
High entropy alloy superconductors represent a unique blend of advanced material systems and quantum physics, offering significant potential for advancing superconducting technologies. In this study, we report a detailed theoretical and experimental investigation of high entropy alloy superconductors Ta0.2Nb0.2V0.2Ti0.2X0.2 (X = Zr and Hf). Our study unveils that both the materials crystallize in a body-centered cubic structure (space group: I m -3 m) and exhibit bulk superconductivity with a superconducting onset temperature of (Tonset C ) of 5 K for X = Hf and 6.19 K for X = Zr sample. Our detailed analysis, including magnetization, resistivity, heat capacity measurements, and density functional theory (DFT) calculations indicates moderately coupled isotropic s-wave superconductivity in these materials. Our DFT results find significant spectral weight at the Fermi energy and phonon spectra is free of imaginary modes, confirming the dynamical stability and metallic nature of these alloys. Remarkably, we have observed a high upper critical field (HC2(0)) surpassing the Pauli paramagnetic limit for the X = Hf sample and explained it on the basis of the increased spin-orbit coupling in the structure. Ta0.2Nb0.2V0.2Ti0.2Zr0.2, on the other hand, shows a conventional HC2 behaviour. With the dynamical stability of these alloys, excellent normal state metallic nature, high micro-hardness, and high upper critical field, these samples emerge as potential candidates for future applications in superconducting devices.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Symmetry-Projected Spin-AGP Methods Applied to Spin Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Zhiyuan Liu, Thomas M. Henderson, Gustavo E. Scuseria
Symmetry-projected wave function methods capture static correlation by breaking and restoring the symmetries of a system. In this article, we present the symmetry-projected spin antisymmetrized geminal power (spin-AGP) state projected onto space group symmetry as well as complex conjugation, spin-flip, and time-reversal symmetries. The method is benchmarked on the 1D XXZ model and 2D $ \mathrm{J_1-J_2}$ model with square and triangular lattices. Our results indicate that symmetry projection methods provide a powerful tool for frustrated spin systems.
Strongly Correlated Electrons (cond-mat.str-el)
Submitted to JCP
Structural Control of Atomic Silicon Wires
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Furkan M. Altincicek (1), Christopher C. Leon (1), Taras Chutora (1), Max Yuan (1), Roshan Achal (2), Lucian Livadaru (1), Jason Pitters (3), Robert Wolkow (1 and 2) ((1) University of Alberta, Edmonton, Canada, (2) Quantum Silicon Inc., Edmonton, Canada, (3) National Research Council of Canada, Edmonton, Canada)
Bare Si(100)-2$ \times$ 1 surface atoms exhibit a buckled structure where one Si atom in a dimer is lowered while the other is raised, leading to two possible buckling configurations equivalent in energy. The relatively low energy barrier between these configurations allows dimers to flip rapidly and uncontrollably unless stabilized by surface defects or observed at low temperatures due to reduced thermal energy using Scanning Tunneling Microscopy (STM). This rapid flipping results in a time-averaged symmetric appearance under STM. In this study, we investigated variable length buckled dimer wires on the hydrogenated Si(100) surface composed of silicon dangling bonds for the first time. We demonstrate that on degenerate p-type silicon at 4.5 K, the rapid switching of these dimers can be frozen at low scanning biases. It is shown that the stability of a fixed buckled configuration increases with wire length. Such buckled wires can however be controllably flipped using a bias pulse. A line as long as 37 dimers was repeatedly uniformly flipped by a single pulse delivered near one terminus of the wire. The tip-directed flipping of a particular wire does not switch adjacent wires, suggesting binary wires can make well isolated rewritable binary memory elements. Furthermore, at sufficiently high biases switching generates telegraph noise that could be of utility for random number generation. The integration and encapsulation of these wires with previously described silicon dangling bond-made logic gates and binary wires might allow for self contained actuation and readout without requiring any role of an STM tip.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 5 figures
Light-Induced Spin Slanting in 2D Multiferroic Magnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Jiangyu Zhao, Yangyang Feng, Kaiying Dou, Xinru Li, Ying Dai, Baibiao Huang, Yandong Ma
Controlling spin orientation of two-dimensional (2D) materials has emerged as a frontier of condensed-matter physics, resulting in the discovery of various phases of matter. However, in most cases, spin orientation can be stablished only at specific directions of out-of-plane and in-plane, which is a drawback compared with three-dimensional systems, limiting exploration of novel physics. Here, we introduce a methodology for manipulating spin slanting in 2D multiferroic materials through ultrafast pulses of light. Based on model analysis, we find that simultaneous triggering spin-orbit coupling induced interactions from in-plane and out-of-plane orbitals can generate spin slanting. By choosing 2D multiferroic materials with specific low-energy composition endowed by symmetry, such triggering can be readily achieved through ultrafast light illumination, leading to light-induced spin slanting. Using real-time time-dependent density-functional theory, we demonstrate this approach in multiferroic single-layer CuCr2Se4. This study provides an efficient way to manipulate spin orientation in 2D materials and establishes a general platform to explore physics and applications associated with spin slanting.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Anomalous Hall Effect in Type IV 2D Collinear Magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Ling Bai, Run-Wu Zhang, Wanxiang Feng, Yugui Yao
We identify a previously unrecognized class of two-dimensional (2D) collinear magnetic phase that extends beyond the established categories of ferromagnets, antiferromagnets, and altermagnets. These type IV 2D collinear magnets exhibit spin-degenerate bands in the nonrelativistic limit, yet support time-reversal symmetry-breaking responses, such as the anomalous Hall effect (AHE), despite having zero net magnetization. Based on spin layer group analysis, we derive the symmetry criteria for this phase and perform first-principles calculations to screen viable candidate materials from 2D databases. Using monolayer Hf2S as a prototype, we demonstrate that in the absence of spin-orbit coupling, the bands are spin degenerate, while its inclusion induce an AHE driven by spin-polarized and even spin-neutral currents, accompanied by a symmetry-protected, truly full-space persistent spin texture. These findings expand the classification of magnetic phases and broaden avenues for realizing unconventional spintronic functionalities in two dimensions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages
Contrasting Light-Induced Spin Torque in Antiferromagnetic and Altermagnetic Systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Light-matter interaction has become one of the promising routes to manipulating various physical feature of quantum materials in an ultrafast kinetics. In this work, we focus on the nonlinear optical effects of the spintronic behavior in antiferromagnetic (AFM) and altermagnetic (AM) systems with compensated magnetic moments, which has been extensively attractive for their potential applications. With vanishing net magnetic moments, one of the main concerns is how to distinguish and disentangle AFMs and AMs in experiments, as they usually behave similarly in many susceptibility measurements. To address this challenge, we propose that linearly polarized light could trigger contrasting nonequilibrium local spin torques in these systems, unravelling hidden light-induced spintronic behaviors. In general, one could achieve light-induced spin canting in AMs, while only Neel vector torques in AFMs. We scrutinize and enumerate their symmetry constraints of all 122 magnetic point groups. We also adopt low energy Hamiltonian models and first-principles calculations on two representative materials to illustrate our theory. Our work provides a new perspective for the design and optimization of spintronic devices.
Materials Science (cond-mat.mtrl-sci)
3 figures, a slightly longer version than will be published in PRL
Laser-driven solid-state synthesis of high-entropy oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Peng wei, Yiwen Liu, Hao Bai, Lei Zhuang, Hulei Yu, Yanhui Chu
The vast compositional and structural landscape of high-entropy oxides (HEOs) grants them a wide range of potentially valuable physicochemical properties. However, the elemental immiscibility and crystal complexity limit their controllable synthesis. Here, we report a laser-driven solid-state synthesis technique that enables high-throughput production of HEOs with different crystal structures, including rock-salt, perovskite, spinel, fluorite, pyrochlore, tantalate, and silicate, incorporating up to 20 cationic elements. Typically, we successfully synthesize all types of high-entropy rare-earth disilicates (HEREDs), including A-, {\alpha}-, \b{eta}-, {\gamma}-, {\delta}-, F-, and G-type phase structures, with up to 15 rare-earth elements in the A site and 5 transition-metal elements in the B site. Benefiting from their unique G-type phase structure and 20-cation composition, HEREDs are endowed with the new functionality of microwave absorption (effective absorption bandwidth of 4.3 GHz). Our work not only realizes the controllable synthesis of HEOs with vast compositional and structural space but also offers them new physicochemical properties, making them highly promising for a diverse array of structural and functional applications.
Materials Science (cond-mat.mtrl-sci)
Determining 3D atomic coordinates of light-element quantum materials using ptychographic electron tomography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Na Yeon Kim, Hanfeng Zhong, Jianhua Zhang, Colum M. O’Leary, Yuxuan Liao, Ji Zou, Haozhi Sha, Minh Pham, Weiyi Li, Yakun Yuan, Ji-Hoon Park, Dennis Kim, Huaidong Jiang, Jing Kong, Miaofang Chi, Jianwei Miao
Understanding quantum materials at the atomic scale requires precise 3D characterization of atomic positions and crystal defects. However, resolving the 3D structure of light-element materials (Z <= 8) remains a major challenge due to their low contrast and beam damage in electron microscopy. Here, we demonstrate ptychographic atomic electron tomography (pAET), achieving sub-angstrom 3D atomic precision (11 pm) in light elements, marking the first-ever experimental realization of 3D atomic imaging for light-element materials. Using twisted bilayer graphene as a model system, we determine the 3D atomic coordinates of individual carbon atoms, revealing chiral lattice distortions driven by van der Waals interactions that exhibit meron-like and skyrmion-like structures. These findings provide direct insights into the interplay between 3D chiral lattice deformation and electronic properties in moire materials. Beyond TBG, pAET offers a transformative approach for 3D atomic-scale imaging across quantum materials, 2D heterostructures, functional oxides, and energy materials.
Materials Science (cond-mat.mtrl-sci), Instrumentation and Detectors (physics.ins-det)
Significant ballistic thermal transport across graphene layers: effect of nanoholes and lithium intercalation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
John Crosby, Haoran Cui, Yan Wang
Porous graphene and graphite are increasingly utilized in electrochemical energy storage and solar-thermal applications due to their unique structural and thermal properties. In this study, we conduct a comprehensive analysis of the lattice thermal transport and spectral phonon characteristics of holey graphite and multilayer graphene. Our results reveal that phonon modes propagating obliquely with respect to the graphene basal planes are the primary contributors to cross-plane thermal transport. These modes exhibit a predominantly ballistic nature, resulting in an almost linear increase in cross-plane thermal conductivity with the number of layers. The presence of nanoholes in graphene induces a broadband suppression of cross-plane phonon transport, whereas lithium ion intercalation shows potential to enhance it. These findings provide critical insights into the mechanisms governing cross-plane heat conduction in key graphene-based structures, offering valuable guidance for thermal management and engineering of van der Waals materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Stochastic elastohydrodynamics of soft valves
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Mengfei He, Sungkyu Cho, Gianna Dafflisio, Sitaram Emani, L. Mahadevan
Soft valves serve to modulate and rectify flows in complex vasculatures across the tree of life, e.g. in the heart of every human reading this. Here we consider a minimal physical model of the heart mitral valve modeled as a flexible conical shell capable of flow rectification via collapse and coaptation in an impinging (reverse) flow. Our experiments show that the complex elastohydrodynamics of closure features a noise-activated rectification mechanism. A minimal theoretical model allows us to rationalize our observations while illuminating a dynamical bifurcation driven by stochastic hydrodynamic forces. Our theory also suggests a way to trigger the coaptation of soft valves on demand, which we corroborate using experiments, suggesting a design principle for their efficient operation.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Accelerating Multi-Objective Collaborative Optimization of Doped Thermoelectric Materials via Artificial Intelligence
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Yuxuan Zeng, Wenhao Xie, Wei Cao, Tan Peng, Yue Hou, Ziyu Wang, Jing Shi
The thermoelectric performance of materials exhibits complex nonlinear dependencies on both elemental types and their proportions, rendering traditional trial-and-error approaches inefficient and time-consuming for material discovery. In this work, we present a deep learning model capable of accurately predicting thermoelectric properties of doped materials directly from their chemical formulas, achieving state-of-the-art performance. To enhance interpretability, we further incorporate sensitivity analysis techniques to elucidate how physical descriptors affect the thermoelectric figure of merit (zT). Moreover, we establish a coupled framework that integrates a surrogate model with a multi-objective genetic algorithm to efficiently explore the vast compositional space for high-performance candidates. Experimental validation confirms the discovery of a novel thermoelectric material with superior $ zT$ values in the medium-temperature regime.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Machine Learning (cs.LG), Neural and Evolutionary Computing (cs.NE)
Inhomogeneous entanglement structure in monoaxial chiral ferromagnetic quantum spin chain
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Kentaro Nishimura, Ryosuke Yoshii
Chiral magnets, characterized by inhomogeneous magnetic moment arrangements, have attracted significant attention recently due to their topological orders, such as magnetic skyrmion lattices and chiral soliton lattices. In this work, we investigate the entanglement entropy of \textit{quantum} chiral magnets and demonstrate that it reflects the inhomogeneous nature of the ground state. We perform numerical simulations of a one-dimensional monoaxial chiral ferromagnetic chain with Zeeman term using the density matrix renormalization group method. Our results show that the entanglement entropy exhibits oscillatory behavior, which can be tuned by varying the external magnetic field. Analysis of the local magnetization and spin chirality further confirms that these oscillations correspond to solitonic structures. Moreover, our findings suggest that the entanglement entropy can serve as a probe for detecting the vacuum structure, providing new insights into quantum correlations.
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 10 figures
Dynamics and fragmentation of bosons in an optical lattice inside a cavity using Wannier and position bases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-14 20:00 EDT
Christopher Gerard R. Sevilla, Jayson G. Cosme
The atom-cavity system is a versatile platform for emulating light-matter systems and realizing dissipation-induced phases, such as limit cycles (LCs) and time crystals. Here, we study the dynamics of a Bose-Einstein condensate (BEC) inside an optical cavity with transverse pumping and an additional intracavity optical lattice along the cavity axis. Specifically, we explore the theoretical predictions obtained from expanding the atomic field operators of the second-quantized Hamiltonian in two ways: (i) position basis and (ii) single-band Wannier basis. Both bases agree on the existence of most types of static and dynamical phases. However, matter-wave superradiance, captured within the position basis, is absent in the Wannier basis. Moreover, we show that they predict different types of LCs due to the inherent limitation of the single-band Wannier expansion, highlighting the importance of including higher energy bands to correctly capture certain phenomena. Using truncated Wigner approximation (TWA), we investigate the fragmentation dynamics of the BEC. We demonstrate that both position and Wannier bases qualitatively agree on the photon-mediated fragmentation dynamics of the BEC in the density-wave (DW) phase, despite the absence of interatomic interactions. The presence of interatomic interaction leads to further fragmentation, which can only be observed in larger system sizes. Finally, we predict a sudden increase in the fragmentation behavior for larger pump intensities, which may hint at an eventual transition to a Mott insulating (MI) phase.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
16 pages, 17 figures
Oxygen-isotope effect on the density wave transitions in La$_3$Ni$2$O${7}$ and La$_4$Ni$3$O${10}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-14 20:00 EDT
Rustem Khasanov, Vahid Sazgari, Igor Plokhikh, Marisa Medarde, Ekaterina Pomjakushina, Tomasz Klimczuk, Szymon Królak, Michał J. Winiarski, Thomas J. Hicken, Hubertus Luetkens, Zurab Guguchia, Dariusz J. Gawryluk
The isotope effect in solid-state physics is fundamental to understanding how atomic mass influences the physical properties of materials and provides crucial insights into the role of electron-phonon coupling in the formation of various quantum states. In this study, we investigate the effect of oxygen isotope ($ ^{16}$ O/$ ^{18}$ O) substitution on density wave transitions in the double- and triple-layer Ruddlesden-Popper nickelates La$ _3$ Ni$ _2$ O$ _7$ and La$ 4$ Ni$ 3$ O$ {10}$ . The charge-density wave (CDW) transitions in both systems are influenced by isotope substitution, with the CDW transition temperature ($ T{\rm CDW}$ ) shifting to higher values in the $ ^{18}$ O-substituted samples. In contrast, the isotope effect on the spin-density wave (SDW) transition temperature ($ T{\rm SDW}$ ) differs between the two systems. Specifically, a significant isotope effect on $ T{\rm SDW}$ is observed only in La$ _4$ Ni$ 3$ O$ {10}$ , where the CDW and SDW orders are intertwined. This interplay results not only in equal values for $ T{\rm CDW}$ and $ T{\rm SDW}$ but also in an identical isotope effect on both transitions. In contrast, in La$ _3$ Ni$ _2$ O$ 7$ , where the SDW transition occurs at a temperature distinct from the CDW, no isotope effect is observed on $ T{\rm SDW}$ .
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 4 figures
Positive Terahertz Photoconductivity in CdHgTe Under Hydrostatic Pressure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Ivan Yahniuk, Dmitriy A. Kozlov, Mariya D. Moldavskaya, Leonid E. Golub, Vasily V. Bel’kov, Ivan A. Dmitriev, Sergey S. Krishtopenko, Frederic Teppe, Yurii Ivonyak, Artem Bercha, Grzegorz Cywiński, Wojciech Knap, Sergey D. Ganichev
Positive terahertz photoconductivity is observed at room temperature in CdHgTe thin films with different Cd contents. We show that electron gas heating caused by Drude-like absorption results in positive photoconductivity because of the interband activation mechanism specific for undoped narrow-gap semiconductors and semimetals. Applying intense terahertz radiation, we observed that the photoconductivity saturates at high intensities, which was found to be caused by absorption bleaching. Both the magnitude of the photoconductivity and the saturation intensity are shown to exhibit an exponential dependence on the hydrostatic pressure. We show that this is a consequence of the fact that both phenomena are controlled by the ratio of energy and momentum relaxation times.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Role of Heat Transport in All-Optical Helicity-Independent Magnetization Switching
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
V. Raposo, J. Hohlfeld, S. Mangin, E. Martínez
Single-shot all-optical helicity independent switching processes are investigated using advanced micromagnetic modeling in a ferrimagnetic thin film embedded in a multilayer stack. Building on recent experimental findings, our multiscale simulations realistically account for heat transport in the stack, focusing on the influence of a metallic copper underlayer with varying thickness. We analyze how this thermal transport affects the final magnetic state of the ferrimagnet as a function of both the laser pulse duration and fluence. Our results reproduce the experimentally observed switching behaviors and elucidate the physical mechanisms that govern the emergence of three distinct final magnetic states. In particular, we demonstrate how these states are critically influenced by the thickness of the underlying copper layer.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 4 figures
An Efficient Integrator Scheme for Sampling the (Quantum) Isobaric-Isothermal Ensemble in (Path Integral) Molecular Dynamics Simulations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Weihao Liang, Sihan Wang, Cong Wang, Weizhou Wang, Xinchen She, Chongbin Wang, Jiushu Shao, Jian Liu
Because most chemical or biological experiments are performed under conditions of controlled pressure and temperature, it is important to simulate the isobaric-isothermal ensemble at the atomic level to reveal the microscopic mechanism. By extending our configuration sampling protocol for the canonical ensemble, we propose a unified middle scheme to sample the coordinate (configuration) and volume distribution and thereby are able to accurately simulate either classical or quantum isobaric-isothermal processes. Various barostats and thermostats can be employed in the unified middle scheme for simulating real molecular systems with or without holonomic constraints. In particular, we demonstrate the recommended middle scheme by employing the Martyna-Tuckerman-Tobias-Klein barostat and stochastic cell-rescaling barostat, with the Langevin thermostat, in molecular simulation packages (DL_POLY, Amber, Gromacs, etc.). Benchmark numerical tests show that, without additional numerical effort, the middle scheme is competent in increasing the time interval by a factor of 5~10 to achieve the same accuracy of converged results for most thermodynamic properties in (path integral) molecular dynamics simulations.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Chemical Physics (physics.chem-ph), Classical Physics (physics.class-ph), Computational Physics (physics.comp-ph)
A mesoscopic model for the rheology of dilute and semidilute solutions of wormlike micelles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Avishek Kumar, Rico F. Tabor, P.Sunthar, J. Ravi Prakash
The concept of a persistent worm' is introduced, representing the smallest possible length of a wormlike micelle, and modelled by a bead-spring chain with sticky beads at the ends. Persistent worms are allowed to combine with each other at their sticky ends to form wormlike micelles with a distribution of lengths, and the semiflexibility of a wormlike micelle is captured with a bending potential between springs, both within and across persistent worms that stick to each other. Multi-particle Brownian dynamics simulations of such polydisperse and polyflexible’ wormlike micelles, with hydrodynamic interactions included and coupled with reversible scission/fusion of persistent worms, are used to investigate the static and dynamic properties of wormlike micellar solutions in the dilute and unentangled semidilute concentration regimes. The influence of the sticker energy and persistent worm concentration are examined and simulations are shown to validate theoretical mean-field predictions of the universal scaling with concentration of the chain length distribution of linear wormlike micelles, independent of the sticker energy. The presence of wormlike micelles that form rings is shown not to affect the static properties of linear wormlike micelles, and mean-field predictions of ring length distributions are validated. Linear viscoelastic storage and loss moduli are computed and the unique features in the intermediate frequency regime compared to those of homopolymer solutions are highlighted. The distinction between Rouse and Zimm dynamics in wormlike micelle solutions is elucidated, with a clear identification of the onset of the screening of hydrodynamic interactions with increasing concentration.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
34 pages, 22 figures, submitted to the Journal of Rheology
Circular dichroism in resonant photoelectron diffraction as a direct probe of sublattice magnetization in altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Altermagnets are a new class of materials, which are promising for spintronics applications, but the experimental proof of a finite sublattice magnetisation is often difficult. Here it is shown that in altermagnets, there exists a large magnetic circular dichroism (CD) in the resonant photoelectron diffraction (RPED) pattern. RPED calculations are performed for MnTe at the Mn L$ _{2,3}$ -edge resonance, using a combination of atomic multiplet and multiple scattering theory. A large CD of purely magnetic origin is found for light helicity parallel to the Néel vector. The magnetic CD has the same angular distribution as the difference between the structural RPED of the two magnetic sublattices and its amplitude is approximately proportional to the magnetic CD in X-ray absorption of a single sublattice. This shows that RPED-CD provides a direct experimental probe of the staggered magnetization.
Materials Science (cond-mat.mtrl-sci)
Giant Orbital Torque-driven Picosecond Switching in Magnetic Tunnel Junctions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Yuxuan Yao, Chen Xiao, Xiaobai Ning, Wenlong Cai, Xianzeng Guo, Zongxia Guo, Kailin Yang, Danrong Xiong, Zhengjie Yan, Shiyang Lu, Hongchao Zhang, Siyuan Cheng, Renyou Xu, Dinghao Ma, Chao Wang, Zhaohao Wang, Daoqian Zhu, Kaihua Cao, Hongxi Liu, Aurélien Manchon, Weisheng Zhao
Orbital Hall effect was recently discovered as a novel pathway for driving magnetic moment. However, the integration of orbital Hall effect in magnetic memories suffers from low orbital-to-spin conversion efficiency and incompatibility with magnetic tunnel junctions. Here we demonstrate an orbital Hall effect-driven magnetic tunnel junction based on Ru/W bilayer, where the Ru layer possesses a strong orbital Hall conductivity and the {\alpha}-W layer features an orbital-to-spin conversion efficiency exceeding 90% because of the large orbit-spin diffusivity. By harnessing the giant orbital torque, we achieve a 28.7-picosecond switching and a five to eight-fold reduction in driving voltages over conventional spin-orbit torque magnetic memories. Our work bridges the critical gap between orbital effects and magnetic memory applications, significantly advancing the field of spintronics and orbitronics.
Materials Science (cond-mat.mtrl-sci)
Synthesis of intrinsic magnetic topological insulator MnBi2nTe3n+1 family by chemical vapor transport method with feedback regulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Heng Zhang, Yiying Zhang, Yong Zhang, Bo Chen, Jingwen Guo, Yu Du, Jiajun Li, Hangkai Xie, Zhixin Zhang, Fuwei Zhou, Tianqi Wang, Wuyi Qi, Xuefeng Wang, Fucong Fei, Fengqi Song
MnBi2nTe3n+1 (MBT) is a representative family of intrinsic magnetic topological insulators, in which numerous exotic phenomena such as the quantum anomalous Hall effect are expected. The high-quality crystal growth and magnetism manipulation are the most essential processes. Here we develop a modified chemical vapor transport method using a feedback-regulated strategy, which provides the closed-loop control of growth temperature within +/- 0.1 degree Celsius. Single crystals of MnBi2Te4, MnBi4Te7, and MnBi6Te10 are obtained under different temperature intervals respectively, and show variable tunability on magnetism by finely tuning the growth temperatures. Specifically, the cold-end temperatures not only vary the strength of antiferromagnetic coupling in MnBi2Te4, but also induce magnetic ground state transitions from antiferromagnetism to ferromagnetism in MnBi4Te7 and MnBi6Te10. In MnBi2Te4 with optimized magnetism, quantized transport with Chern insulator state is also realized at the low field of 3.7 T. Our results provide a systematic picture for the crystal growth and the rich magnetic tunability of MBT family, providing richer platforms for the related researches combining magnetism and topological physics.
Materials Science (cond-mat.mtrl-sci)
Adv. Mater. 2025, 2405686
Designing atomic-scale resistive circuits in topological insulators through vacancy-induced localized modes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Cunyuan Jiang, Weicen Dong, Matteo Baggioli
We demonstrate that vacancies can induce topologically protected localized electronic excitations within the bulk of a topological insulator, and when sufficiently close, give rise to one-dimensional propagating chiral bulk modes. We show that the dynamics of these modes can be effectively described by a tight-binding Hamiltonian, with the hopping parameter determined by the overlap of electronic wave functions between adjacent vacancies, accurately predicting the low-energy spectrum. Building on this phenomenon, we propose that vacancies in topological materials can be utilized to design atomic-scale resistive circuits, and estimate the associated resistance as a function of the vacancy distribution’s geometric properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
6 pages, 4 figures
Dynamics of surface electrons in a topological insulator: cyclotron resonance at room temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
I. Mohelsky, F. Le Mardele, J. Dzian, J. Wyzula, X. D. Sun, C. W. Cho, B. A. Piot, M. Shankar, R. Sankar, A. Ferguson, D. Santos-Cottin, P. Marsik, C. Bernhard, A. Akrap, M. Potemski, M. Orlita
The ability to manipulate the surface states of topological insulators using electric or magnetic fields under ambient conditions is a key step toward their integration into future electronic and optoelectronic devices. Here, we demonstrate - using cyclotron resonance measurements on a tin-doped BiSbTe$ _2$ S topological insulator - that moderate magnetic fields can quantize massless surface electrons into Landau levels even at room temperature. This finding suggests that surface-state electrons can behave as long-lived quasiparticles at unexpectedly high temperatures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 3 figures
Towards quantitative understanding of quantum dot ensemble capacitance-voltage spectroscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Nico F. Brosda, Phil J. Badura, İsmail Bölükbaşı, İbrahim Engin, Patrick Lindner, Sascha R. Valentin, Andreas D. Wieck, Björn Sothmann, Arne Ludwig
Inhomogeneous ensembles of quantum dots (QDs) coupled to a charge reservoir are widely studied by using, e.g., electrical methods like capacitance-voltage spectroscopy. We present experimental measurements of the QD capacitance as a function of varying parameters such as ac frequency and bath temperature. The experiment reveals distinct shifts in the position of the capacitance peaks. While temperature-induced shifts have been explained by previous models, the observation of frequency-dependent shifts has not been explained so far. Given that existing models fall short in explaining these phenomena, we propose a refined theoretical model based on a master equation approach which incorporates energy-dependent tunneling effects. This approach successfully reproduces the experimental data. We highlight the critical role of energy-dependent tunneling in two distinct regimes: at low temperatures, ensemble effects arising from energy-level dispersion in differently sized QDs dominate the spectral response; at high temperatures and frequencies, we observe a peak shift of a different nature, which is best described by optimizing the conjoint probability of successive in- and out-tunneling events. Our findings contribute to a deeper understanding of tunnel processes and the physical properties of QD ensembles coupled to a common reservoir, with implications for their development in applications such as single-photon sources and spin qubits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech)
13 pages, 9 figures. Nico F. Brosda and Phil J. Badura contributed equally. Submitted to Physical Review B
Elasticity of bidisperse attractive particle systems
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Yaqi Zhao, Antoine Sanner, Luca Michel, David S. Kammer
Bidisperse particle systems are common in both natural and engineered materials, and it is known to influence packing, flow, and stability. However, their direct effect on elastic properties, particularly in systems with attractive interactions, remains poorly understood. Gaining insight into this relationship is important for designing soft particle-based materials with desired mechanical response. In this work, we study how particle size ratio and composition affect the shear modulus of attractive particle systems. Using coarse-grained molecular simulations, we analyze systems composed of two particle sizes at fixed total packing fraction and find that the shear modulus increases systematically with bidispersity. To explain this behavior, we develop two asymptotic models following limiting cases: one where a percolated network of large particles is stiffened by small particles, and another where a small-particle network is modified by embedded large particles. Both models yield closed-form expressions that capture the qualitative trends observed in simulations, including the dependence of shear modulus on size ratio and relative volume fraction. Our results demonstrate that bidispersity can enhance elastic stiffness through microstructural effects, independently of overall density, offering a simple strategy to design particle-based materials with tunable mechanical properties.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
20 pages, 5 figures
Investigation into the low temperature state of the spin-ice material Dy_2 Ti_2 O_7
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Mariano Marziali Bermudez, R. A. Borzi, D. A. Tennant, S. A. Grigera
The thermal equilibrium properties of the spin-ice material DTO, including specific heat, magnetization, and spin correlations, could be successfully reproduced by a model featuring magnetic interactions up to the third nearest neighbor and long-ranged dipolar forces. With the best-fit parameters, the model predicts an ordered ground state which breaks the cubic symmetry of the lattice. In this work, we analyze results from a neutron scattering experiment in which, instead of sharp Bragg peaks, a diffuse pattern was observed down to 300mK, despite very slow cooling [A. M. Samarakoon et al., Physical Review Research 4,033159 (2022).]. Using a reverse Monte Carlo approach, we found compatible spin configurations, analyze the suitability of antiferromagnetic spin chains as building blocks for the ground-state and provide various measures of correlation and calculate their energy. Our analysis suggests that while infinitely long chains are not present in the experimental configuration, antiferromagnetic spin chains provide a good approximation of the data. There are indications of possible evidence for short-range chains, but further investigation is needed for confirmation.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 8 figures
Explicit core-hole single-particle methods for L- and M- edge X-ray absorption and electron energy-loss spectra
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Esther A. B. Johnsen, Naoki Horiuchi, Toma Susi, Michael Walter
Single-particle methods based on Kohn-Sham unoccupied states to describe near-edge X-ray absorption (XAS) spectra are routinely applied for the description of K-edge spectra, as there is no complication due to spin-orbit (SO) coupling. L- and M-edge spectra are often addressed via variants of time-dependent density functional theory (TDDFT) based on SO calculations. Here, we present a computationally efficient implementation based on single-particle calculations with core holes within the frozen-core approximation. Combined with a semiempirical energy shift and a fixed spin-orbit splitting, this allows for a prediction of experimental spectra on the absolute energy scale. Such spectra are compared to linear-response TDDFT for molecules and show similar or even better match with experiment, except for multiplet effects that are not covered by the single-particle approximation. A similar picture emerges for solids, where good qualitative and sometimes even quantitative agreement to XAS and electron energy-loss spectra is achieved.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
12 pages, 12 figures
A comparative review of recent results on supercritical anomalies in two-dimensional kinetic Ising and Blume-Capel ferromagnets
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Gloria M. Buendía, Celeste Mendes, Per Arne Rikvold
Following the unexpected experimental discovery of ``sideband’’ peaks in the fluctuation spectrum of thin Co films driven by a slowly oscillating magnetic field with a constant bias [P.~Riego et al., Phys. Rev. Lett. 118, 117202 (2017)] numerical studies of two-state Ising and three-state Blume-Capel (BC) ferromagnets in this dynamically supercritical regime have flourished and been successful in explaining this phenomenon. Here, we give a comparative review of this new literature and its connections to earlier work. Following an introduction and a presentation of the two models and the computational method used in many of these studies, we present numerical results for both models. Particular attention is paid to the fact that zero spins in the BC model tend to collect at he interfaces between regions of the two nonzero spin values, +/-1. We present strong arguments that this phenomenon leads to a reduction of the effective interface tension in the BC model, compared to the Ising model.
Statistical Mechanics (cond-mat.stat-mech)
18 pages, 6 figures
Calculation of Elastic Constants of UO$_2$ using the Hubbard-Corrected Density-Functional Theory DFT+U
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Mahmoud Payami, Samira Sheykhi, Mohammad-Reza Basaadat
Uranium dioxide which is used as a fuel in light water nuclear reactors, is continually exposed to radiation damage originated from the collision of high-energy particles. Accumulation of the resulting defects gives rise to the evolution in the micro-structure of the fuel which in turn brings about local tensions and strains in the fuel. One of the after effects due to evolution of micro-structure is the swelling of fuel which can damage the fuel cladding and cause environmental contamination by leakage of radioactive particles. Hence, it is vital to continually monitor the evolution of micro-structure and to analyze the changes in mechanical properties of the fuel. The study of elastic constants and analysis of their behavior is very helpful in understanding the mechanical properties of the fuel. In this research, using the Hubbard-corrected first-principles density-functional theory method, we have calculated the elastic constants of the uranium dioxide single crystal and compared the results with existing experimental data. In addition, using the Voigt, Reuss, and Hill models, we have estimated the mechanical properties for the poly-crystalline fresh fuel. The results show a very good agreement between the theory and experiment. Accordingly, we can reliably extend our method of calculations to the complicated system of irradiated fuel pellet, which is in the form of a poly-crystal and hosts various defects.
Materials Science (cond-mat.mtrl-sci)
5 pages, 1 figure
Bifurcations and Phase Transitions in the Origins of Life
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-14 20:00 EDT
Ricard Solé, Manlio De Domenico
The path toward the emergence of life in our biosphere involved several key events allowing for the persistence, reproduction and evolution of molecular systems. All these processes took place in a given environmental context and required both molecular diversity and the right non-equilibrium conditions to sustain and favour complex self-sustaining molecular networks capable of evolving by natural selection. Life is a process that departs from non-life in several ways and cannot be reduced to standard chemical reactions. Moreover, achieving higher levels of complexity required the emergence of novelties. How did that happen? Here, we review different case studies associated with the early origins of life in terms of phase transitions and bifurcations, using symmetry breaking and percolation as two central components. We discuss simple models that allow for understanding key steps regarding life origins, such as molecular chirality, the transition to the first replicators and cooperators, the problem of error thresholds and information loss, and the potential for “order for free” as the basis for the emergence of life.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Adaptation and Self-Organizing Systems (nlin.AO), Biological Physics (physics.bio-ph)
19 pages, 5 figures, 3 boxes
Stationary-state dynamics of interacting phase oscillators in presence of noise and stochastic resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Anish Acharya, Mrinal Sarkar, Shamik Gupta
We explore the impact of global resetting on Kuramoto-type models of coupled limit-cycle oscillators with distributed frequencies both in absence and presence of noise. The dynamics comprises repeated interruption of the bare dynamics at random times with simultaneous resetting of phases of all the oscillators to a predefined state. To characterize the stationary-state behavior, we develop an analytical framework that spans across different generalizations of the Kuramoto model involving either quenched or annealed disorder or both, and for any choice of the natural frequency distribution. The framework applies to the dynamics both in absence and presence of resetting, and is employed to obtain in particular the stationary-state synchronization order parameter of the system, which is a measure of spontaneous ordering among the oscillator phases. A key finding is unveiling of the role of correlations in shaping the ordering dynamics under resetting.
Statistical Mechanics (cond-mat.stat-mech)
16 Pages, 6 figures
Lift force in chiral, compressible granular matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Jarosław Pawłowski, Marcin Dudziak, Matteo Baggioli, Jie Zhang, Piotr Surówka
Micropolar fluid theory, an extension of classical Newtonian fluid dynamics, incorporates angular velocities and rotational inertias and has long been a foundational framework for describing granular flows. However, existing formulations often overlook the contribution of finite odd viscosity, which is a natural occurrence in chiral micropolar fluids where parity and time-reversal symmetries are broken. In this work, we specifically explore the influence of odd viscosity on the lift forces – a less commonly discussed force compared to drag – experienced by a bead immersed in a compressible micropolar fluid. We analyze the lift forces on a bead embedded within a compressible flow of a granular medium, emphasizing the unique role and interplay of microrotations and odd viscosity.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
16 pages, 4 figures
Probes of Full Eigenstate Thermalization in Ergodicity-Breaking Quantum Circuits
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Gabriel O. Alves, Felix Fritzsch, Pieter W. Claeys
The eigenstate thermalization hypothesis (ETH) is the leading interpretation in our current understanding of quantum thermalization. Recent results uncovered strong connections between quantum correlations in thermalizing systems and the structure of free probability theory, leading to the notion of full ETH. However, most studies have been performed for ergodic systems and it is still unclear whether or how full ETH manifests in ergodicity-breaking models. We fill this gap by studying standard probes of full ETH in ergodicity-breaking quantum circuits, presenting numerical and analytical results for interacting integrable systems. These probes can display distinct behavior and undergo a different scaling than the ones observed in ergodic systems. For the analytical results we consider an interacting integrable dual-unitary model and present the exact eigenstates, allowing us to analytically express common probes for full ETH. We discuss the underlying mechanisms responsible for these differences and show how the presence of solitons dictates the behavior of ETH-related quantities in the dual-unitary model. We show numerical evidence that this behavior is sufficiently generic away from dual-unitarity when restricted to the appropriate symmetry sectors.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
18 pages, 12 figures
Clifford algebras and liquid crystalline fermions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
N. Johnson, L. C. Head, O. D. Lavrentovich, A. N. Morozov, G. Negro, E. Orlandini, C. A. Smith, G. M. Vasil, D. Marenduzzo
We show that Clifford algebras provide a natural language to describe the physics of liquid crystal defects in 3D. This framework shows that most of these defects have fermionic nature, as the director field profile on a 2D cross section can algebraically be represented by a spinor. Defects in uniaxial, biaxial nematics and cholesterics are represented by elements belonging to different Clifford algebras, suggesting that there are fundamental distinctions between topological defects in each of these phases. Our theory allows nematic defects to be interpreted as Majorana-like spinors, as defects and antidefects are topologically equivalent, whilst some cholesteric defects, such as screw dislocations, are better viewed as Weyl-like spinors of well-defined chirality. Defects can be described by a ``defect bivector’’, an algebraic element which quantifies the rototranslation associated with them. In cholesterics, fermionic defects of different types can combine to yield composite quasiparticles with either fermionic or bosonic nature. Under cylindrical confinement, these quasiparticles provide the way to understand the structure of screw dislocations. In the bulk, they may condensate to form topological phases, such as blue phases or skyrmion lattices. Our results provide a surprising link between liquid crystals, particle physics, and topological quantum matter.
Soft Condensed Matter (cond-mat.soft)
17 pages, 8 figures, submitted for publication
Phase separation in a chiral active fluid of inertial self-spinning disks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Pasquale Digregorio, Ignacio Pagonabarraga, Francisco Vega Reyes
We show that systematic particle rotations in a fluid composed of disk-shaped spinners can spontaneously lead to phase separation. The phenomenon arises out of a homogeneous and hydrostatic stationary state, due to a pressure feedback mechanism that increases local density fluctuations. We show how this mechanism induces phase separation, coined as Rotation Induced Phase Separation (RIPS), when the active rotation is not properly counterbalanced by translational friction. A low density phase can coexist with a dense chiral liquid due to the imbalance between pressure and stress transmitted through chiral flows when a significant momentum transfer between rotational and translational motion can be sustained. As a consequence, RIPS is expected to appear generically in chiral fluids.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
8 pages, 8 figures
Control of atomic reconstruction and quasi-1D excitons in strain-engineered moiré heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Shen Zhao, Zhijie Li, Zakhar A. Iakovlev, Peirui Ji, Fanrong Lin, Xin Huang, Kenji Watanabe, Takashi Taniguchi, Mikhail M. Glazov, Anvar S. Baimuratov, Alexander Högele
In two-dimensional nearly commensurate heterostructures, strain plays a critical role in shaping electronic behavior. While previous studies have focused on random strain introduced during fabrication, achieving controlled structural design has remained challenging. Here, we demonstrate the deterministic creation of one-dimensional arrays from initially zero-dimensional triangular moiré patterns in MoSe$ _2$ -WSe$ _2$ heterobilayers. This transformation, driven by the interplay of uniaxial strain and atomic reconstruction, results in one-dimensional confinement of interlayer excitons within domain walls, exhibiting near-unity linearly polarized emission related to the confinement-induced symmetry breaking. The width of the domain walls–and consequently the degree of exciton confinement–can be precisely tuned by the interlayer twist angle. By applying out-of-plane electric field, the confined excitons exhibit energy shifts exceeding 100~meV and changes in the fine-structure splitting by up to a factor of two. Our work demonstrates the potential of strain engineering for constructing designer moiré systems with programmable quantum properties, paving the way for future optoelectronic applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Symmetries, Conservation Laws and Entanglement in Non-Hermitian Fermionic Lattices
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Rafael D. Soares, Youenn Le Gal, Chun Y. Leung, Dganit Meidan, Alessandro Romito, Marco Schirò
Non-Hermitian quantum many-body systems feature steady-state entanglement transitions driven by the competition between unitary dynamics and dissipation. In this work, we reveal the fundamental role of conservation laws in shaping this competition. Focusing on translation-invariant non-interacting fermionic models with U(1) symmetry, we present a theoretical framework to understand the structure of the steady-state of these models and their entanglement content based on two ingredients: the nature of the spectrum of the non-Hermitian Hamiltonian and the constraints imposed on the steady-state single-particle occupation by the conserved quantities. These emerge from an interplay between Hamiltonian symmetries and initial state, due to the non-linearity of measurement back-action. For models with complex energy spectrum, we show that the steady state is obtained by filling single-particle right eigenstates with the largest imaginary part of the eigenvalue. As a result, one can have partially filled or fully filled bands in the steady-state, leading to an entanglement entropy undergoing a filling-driven transition between critical sub volume scaling and area-law, similar to ground-state problems. Conversely, when the spectrum is fully real, we provide evidence that local observables can be captured using a diagonal ensemble, and the entanglement entropy exhibits a volume-law scaling independently on the initial state, akin to unitary dynamics. We illustrate these principles in the Hatano-Nelson model with periodic boundary conditions and the non-Hermitian Su-Schrieffer-Heeger model, uncovering a rich interplay between the single-particle spectrum and conservation laws in determining the steady-state structure and the entanglement transitions. These conclusions are supported by exact analytical calculations and numerical calculations relying on the Faber polynomial method.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
40 pages, 14 figures;
Localized plasmonic meron-antimeron pairs in doubly degenerate orbitals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Jie Yang, Xinmin Fu, Jiafu Wang, Yifan Li, Jingxian Zhang, Fangyuan Qi, Yajuan Han, Yuxiang Jia, Guy A E Vandenbosch, Tie Jun Cui, Xuezhi Zheng
Topological defects are pivotal in elucidating kaleidoscopic topological phenomena in different physical systems. Meron-antimeron pairs are a type of topological defects firstly found as soliton solutions to SU(2) Yang-Mills equations in gauge theory, and then identified in condensed matter physics as a type of magnetic quasiparticles created in the context of topological charge conservation. Here, we show that isolated meron-antimeron pairs constitute a new form of optical topological quasiparticles that naturally emerge in doubly degenerate orbitals of plasmonic systems, including fundamental and higher-order ones, and their target-type counterparts. We demonstrate that their topological charges are strictly imposed by orbital indices from the doubly degenerate irreducible representations (irreps) of groups consisting of rotational symmetries, and thus are upper-bounded by the orbital indices imposed by group theory. In addition, we find that there exist highly-localized isolated (anti)merons in plasmonic spin textures, which were previously observed mostly in the form of lattices or clusters. We further demonstrate a locking effect between the chirality of the (anti)merons and the parity of the irreps. Then, the topological origins of the revealed topological quasiparticles, i.e., phase, V-point and L-line singularities in plasmonic fields, are investigated. Finally, a complete symmetry classification of the topological quasiparticles is provided. Generalizing the meron-antimeron pairs to photonic systems provides various possibilities for the applications in optical vectorial imaging, deep-subwavelength sensing and metrology.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Exact large-scale correlations in diffusive systems with general interactions: explicit characterisation without the Dean–Kawasaki equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Aurélien Grabsch, Davide Venturelli, Olivier Bénichou
Characterising the statistical properties of classical interacting particle systems is a long-standing question. For Brownian particles the microscopic density obeys a stochastic evolution equation, known as the Dean–Kawasaki equation. This equation remains mostly formal and linearization (or higher-order expansions) is required to obtain explicit expressions for physical observables, with a range of validity not easily defined. Here, by combining macroscopic fluctuation theory with equilibrium statistical mechanics, we provide a systematic alternative to the Dean–Kawasaki framework to characterize large-scale correlations. This approach enables us to obtain explicit and exact results for dynamical observables such as tracer cumulants and bath-tracer correlations in one dimension, both in and out of equilibrium. In particular, we reveal a generic non-monotonic spatial structure in the response of the bath following a temperature quench. Our approach applies to a broad class of interaction potentials and extends naturally to higher dimensions.
Statistical Mechanics (cond-mat.stat-mech)
6 pages + 17 pages of supplemental material
Magnon and photon blockade in an antiferromagnet-cavity hybrid quantum system
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Vemund Falch, Arne Brataas, Alireza Qaiumzadeh
We investigate both magnon and photon blockade for an antiferromagnetic insulator coupled to a linearly polarized cavity mode. We focus on the cross-Kerr nonlinearity between the two magnon modes, which can be large in antiferromagnets with a weak easy-axis magnetic anisotropy. By numerically solving the Lindblad master equations, we demonstrate that the resulting bright and dark modes, i.e., system eigenmodes that couple strongly and weakly to photons, respectively, exhibit distinct behaviors. The bright mode exhibits both magnon and photon blockade due to a weak effective nonlinearity, while the dark mode only exhibits magnon blockade for a detuned cavity photon. The blockade efficiency can further be optimized by appropriately tuning the competing interactions in the system. In addition, we show that applying a DC magnetic field, which lifts the degeneracy of antiferromagnetic chiral magnon eigenmodes, destroys the dark mode and leads to an unconventional photon blockade. These findings provide a pathway for generating single magnon and photon states useful for quantum information technology based on the underlying large squeezing of antiferromagnetic magnons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 7 figures
Oblique diffraction geometry for the observation of several non-coplanar Bragg reflections under identical illumination
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
C. Detlefs, A. Henningsson, B. Kanesalingam, A. A. W. Cretton, C. Corley-Wiciak, F. T. Frankus, D. Pal, S. Irvine, S. Borgi, H. F. Poulsen, C. Yildirim, L. E. Dresselhaus-Marais
We present a method to determine the strain tensor and local lattice rotation with Dark Field X-ray Microscopy. Using a set of at least 3 non-coplanar, symmetry-equivalent Bragg reflections, the illuminated volume of the sample can be kept constant for all reflections, facilitating easy registration of the measured lattice variations. This requires an oblique diffraction geometry, i.e.the diffraction plane is neither horizontal nor vertical. We derive a closed, analytical expression that allows determination of the strain and lattice rotation from the deviation of experimental observables (e.g.goniometer angles) from their nominal position for an unstrained lattice.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
8 pages, 1 figure. Submitted to Journal of Applied Crystallography
NMR study of supersolid phases in the triangular-lattice antiferromagnet Na2BaCo(PO4)2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Xiaoyu Xu, Zhanlong Wu, Ying Chen, Qing Huang, Ze Hu, Xinyu Shi, Kefan Du, Shuo Li, Rui Bian, Rong Yu, Yi Cui, Haidong Zhou, Weiqiang Yu
We report ultra-low-temperature $ ^{23}$ Na NMR measurements on the Ising triangular lattice antiferromagnet Na$ _2$ BaCo(PO$ _4$ )$ _2$ , which precisely resolve the phase diagram under magnetic field applied along the crystalline $ c$ axis. With increasing field, the NMR spectra resolve three ordered phases with distinct spin configurations: the Y, up-up-down (UUD), and V phases. The spin-lattice relaxation rate $ 1/T_1$ data demonstrate gapless excitations in the Y and V phases, strongly supporting their supersolid nature. However, the phase transitions from the UUD phase to the two supersolid phases exhibit dramatically different behaviors upon cooling. Prior to entering the Y phase, $ 1/T_1$ identifies a gapless regime within the UUD phase, suggesting a Berezinskii-Kosterlitz-Thouless phase above a second-order phase transition. In contrast, the coexistence of the UUD and V phases observed in our experiments provides direct evidence of a first-order phase transition between these phases.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 4 figures
Reentrant transition to collective actuation in active solids with a polarizing field
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Paul Baconnier, Mathéo Aksil, Vincent Démery, Olivier Dauchot
Collective actuation takes place in active solids when the dynamics spontaneously condensates on a few elastic modes. This condensation results from an elasto-active feedback between the deformations of the structure and the orientations of forces exerted by the active units. An external field that polarizes these forces is thus likely to strongly affect the transition to collective actuation. Here, we study the dynamics of elastically coupled polar active units in the presence of such a field, through a combination of model experiments, numerical simulations, and theoretical analysis. Experimentally, we observe that tilting the plane of the experiment polarizes the orientation of the active units and thereby the forces they exert on the elastic structure. Taking advantage of this gravity-induced polarization, we uncover a novel oscillatory regime, distinct from the different oscillating regimes observed in the zero-field limit. The theoretical analysis of the dynamics for a single agent demonstrates that the two oscillating dynamics in the presence of a field map onto the bounded and unbounded phase dynamics of a weighing pendulum. In the many agents case, we observe experimentally and numerically, and demonstrate theoretically, that the polarizing field may facilitate the transition to collective actuation, leading to a reentrant transition.
Soft Condensed Matter (cond-mat.soft)
6 pages, 5 figures, methods
Altermagnetism Without Crystal Symmetry
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Peru d’Ornellas, Valentin Leeb, Adolfo G. Grushin, Johannes Knolle
Altermagnetism is a collinear magnetic order in which opposite spin species are exchanged under a real-space rotation. Hence, the search for physical realizations has focussed on crystalline solids with specific rotational symmetry. Here, we show that altermagnetism can also emerge in non-crystalline systems, such as amorphous solids, despite the lack of global rotational symmetries. We construct a Hamiltonian with two directional orbitals per site on an amorphous lattice with interactions that are invariant under spin rotation. Altermagnetism then arises due to spontaneous symmetry breaking in the spin and orbital degrees of freedom around each atom, displaying a common point group this http URL form of altermagnetism exhibits anisotropic spin transport and spin spectral functions, both experimentally measurable. Our mechanism generalizes to any lattice and any altermagnetic order, opening the search for altermagnetic phenomena to non-crystalline systems.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Collective actuation in active solids in the presence of a polarizing field: a review of the dynamical regimes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Paul Baconnier, Vincent Démery, Olivier Dauchot
Collective actuation in active solids, the spontaneous condensation of the dynamics on a few elastic modes, takes place whenever the deformations of the structure reorient the forces exerted by the active units composing, or embedded in, the solid. In a companion paper, we show through a combination of model experiments, numerical simulations, and theoretical analysis that adding an external field that polarizes the active forces strongly affects the dynamical transition to collective actuation. A new oscillatory regime emerges, and a reentrance transition to collective actuation takes place. Depending on the degenerate, or non-degenerate, nature of the modes on which the dynamics condensates; depending on the orientation of the polarizing field with respect to the stiff or soft direction of the solid, several new dynamical regimes can be observed. The purpose of the present paper is to review these dynamical regimes in a comprehensive way, both for the single-particle dynamics and for the coarse-grained one. Whenever possible the dynamical regimes and the transition between them are described analytically, otherwise numerically.
Soft Condensed Matter (cond-mat.soft)
16 pages, 8 figures, 1 supplementary figure
Imaginary gauge potentials in a non-Hermitian spin-orbit coupled quantum gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-14 20:00 EDT
Junheng Tao, Emmanuel Mercado-Gutierrez, Mingshu Zhao, Ian Spielman
In 1996, Hatano and Nelson proposed a non-Hermitian lattice model containing an imaginary Peierls phase [Phys. Rev. Lett. 77 570-573 (1996)], which subsequent analyses revealed to be an instance of a new class of topological systems. Here, we experimentally realize a continuum analog to this model containing an imaginary gauge potential using a homogeneous spin-orbit coupled Bose-Einstein condensate (BEC). Non-Hermiticity is introduced by adding tunable spin-dependent loss via microwave coupling to a subspace with spontaneous emission. We demonstrate that the resulting Heisenberg equations of motion for position and momentum depend explicitly on the system’s phase-space distribution. First, we observe collective nonreciprocal transport in real space, with a “self-acceleration” that decreases with the BEC’s spatial extent, consistent with non-Hermitian Gross-Pitaevskii simulations. We then examine localized edge states: the relatively strong interactions in our BEC suppress the formation of topological edge states, yielding instead highly excited states localized by an interplay between self-acceleration and wavefunction spreading. Finally, we confirm that our non-Hermitian description remains valid at all times by comparing to a multi-level master-equation treatment.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
A simple method for detection and quantitative estimation of deep levels in a barrier layer of AlGaN/GaN HEMT strucutres by analysis of light induced threshold voltage shift
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-14 20:00 EDT
Maciej Matys, Atsushi Yamada, Yoichi Kamada, Toshihiro Ohki
The characterization of deep levels in AlGaN/GaN heterostructures is one of the most important problems in GaN high electron mobility transistors (HEMTs) technology. This work reports on a technique for determination of deep level concentration in AlGaN/GaN HEMT structures. The proposed method is relatively simple, and it is based on the detection of free holes created by optically induced transitions of electrons from the deep levels to the conduction band. The developed method can detect and provide quantitative estimation of deep level traps in a barrier layer of AlGaN/GaN HEMT structures. Furthermore, it provides a framework for analysis of light induced threshold voltage shift, which includes an important experimental criterion of determination whether the holes are generated or not in the AlGaN/GaN HEMT structures by sub-band gap illumination. The method was verified by applications it to a study of the deep levels in GaN HEMTs grown on various substrates, i.e. SiC and GaN.
Materials Science (cond-mat.mtrl-sci)
Strange Attractors in Complex Networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-14 20:00 EDT
Disorder and noise in physical systems often disrupt spatial and temporal regularity, yet chaotic systems reveal how order can emerge from unpredictable behavior. Complex networks, spatial analogs of chaos, exhibit disordered, non-Euclidean architectures with hidden symmetries, hinting at spontaneous order. Finding low-dimensional embeddings that reveal network patterns and link them to dimensionality that governs universal behavior remains a fundamental open challenge, as it needs to bridge the gap between microscopic disorder and macroscopic regularities. Here, the minimal space revealing key network properties is introduced, showing that non-integer dimensions produce chaotic-like attractors.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Physics and Society (physics.soc-ph)
5 pages, 4 figures, and Supplemental Material. Accepted in Phys. Rev. E
Schottky anomaly in a cavity-coupled double quantum well
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Valerii K. Kozin, Dmitry Miserev, Daniel Loss, Jelena Klinovaja
We present a theoretical study of a mesoscopic two-dimensional electron gas confined in a double quantum well that is coupled to a uniform quasi-static cavity mode via fluctuations of the dipole moment. We focus on the regime of large number of electrons participating in the virtual inter-subband transitions. In this regime, the effective photonic potential is no longer quadratic but, instead, it contains large number of minima. Each minimum represents a nearly harmonic oscillator with the renormalized cavity frequency that is much greater than its bare value. The energy offset of a minimum scales quadratically with respect to the photon coordinate corresponding to this minimum. These energy offsets determine the statistical weight of each minimum, and altogether they result in the additive correction to the heat capacity of the system. This correction exhibits a Schottky anomaly and a 0.5k_B plateau at low temperatures. This behavior can be associated with the emergence of a new degree of freedom. This degree of freedom does not manifest in the optical conductivity and can only be observed via the heat capacity measurement.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Quantum Fluctuation-enhanced Milli-Kelvin Magnetic Refrigeration in Triangular Lattice Magnet GdBO3
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Weijie Lin, Nan Zhao, Zhaoyi Li, Weiran An, Ruixin Guo, Jianqiao Wang, Changzhao Pan, Bo Wen, Jieming Sheng, Liusuo Wu, Shu Guo
Rare-earth-based triangular lattice antiferromagnets, with strong quantum fluctuations and weak magnetic interactions, can often retain large magnetic entropy down to very low temperatures, making them excellent candidates for magnetic refrigeration at ultra-low temperatures. These materials exhibit a substantial magnetocaloric effect (MCE) due to enhanced spin fluctuations, particularly near quantum critical points, which leads to significant changes in magnetic entropy. This study reports on the crystal growth, structure, magnetism, and MCE of a Gd-based triangular lattice material, GdBO3, characterized by a large spin quantum number (S = 7/2). Successive phase transitions (T1 = 0.52 K, T2 = 0.88 K, and T3 = 1.77 K) were observed in zero-field specific heat measurements. Furthermore, thermal dynamic analysis under external magnetic fields identified five distinct phase regions and three quantum critical points for GdBO3. Due to its broad specific heat features and the high density of magnetic Gd3+ ions, we achieved a minimum temperature of 50 mK near the field-induced quantum critical point, using a custom-designed GdBO3-based adiabatic demagnetization refrigerator. Our findings reveal significant quantum fluctuations below 2 K, demonstrating GdBO3’s potential for milli-Kelvin magnetic cooling applications.
Strongly Correlated Electrons (cond-mat.str-el)
Time-reversal symmetric topological superconductivity in Machida-Shibata lattices
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-14 20:00 EDT
Ioannis Ioannidis, Ching-Kai Chiu, Thore Posske
Recent experiments engineered special spin-degenerate Andreev states in atomic cages of adatoms on superconductors, the Machida-Shibata states, revealing a promising building block for quantum matter. Here, we investigate the formation of time-reversal symmetric bands by hybridizing multiple such states and analyzing their electronic topological properties. The low-energy theory shows that competing emerging singlet and triplet superconducting pairings drive the formation of topologically non-trivial phases in symmetry class DIII. Therefore, Kramers pairs of Majorana zero modes appear at the ends of Machida-Shibata chains, while two-dimensional lattices host helical Majorana edge modes. Additionally, we discover extended regions in the Brillouin zone with vanishing superconducting pairings, which can be lifted by repulsive electron interactions. Our findings offer new perspectives for manipulating topological superconductivity and pairings in non-magnetic adatom systems.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages and 6 figures
Optimal Control in Soft and Active Matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
José Alvarado, Erin Teich, David Sivak, John Bechhoefer
Soft and active condensed matter represent a class of fascinating materials that we encounter in our everyday lives – and constitute life itself. Control signals interact with the dynamics of these systems, and this influence is formalized in control theory and optimal control. Recent advances have employed various control-theoretical methods to design desired dynamics, properties, and functionality. Here we provide an introduction to optimal control aimed at physicists working with soft and active matter. We describe two main categories of control, feedforward control and feedback control, and their corresponding optimal control methods. We emphasize their parallels to Lagrangian and Hamiltonian mechanics, and provide a worked example problem. Finally, we review recent studies of control in soft, active, and related systems. Applying control theory to soft, active, and living systems will lead to an improved understanding of the signal processing, information flows, and actuation that underlie the physics of life.
Soft Condensed Matter (cond-mat.soft), Adaptation and Self-Organizing Systems (nlin.AO), Biological Physics (physics.bio-ph)
22 pages
Nonreciprocal Coulomb drag in electron bilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Dmitry Zverevich, Alex Levchenko
We propose a mechanism and develop a theory for nonreciprocal Coulomb drag resistance. This effect arises in electron double-layer systems in the presence of an in-plane magnetic field in noncentrosymmetric conductors or in bilayers with spontaneously broken time-reversal symmetry and without Galilean invariance. We demonstrate the significance of this effect by examining the hydrodynamic regime of the electron liquid. The nonreciprocal component of the transresistance is shown to sensitively depend on the intrinsic conductivity, viscosity of the fluid, and the emergent nonreciprocity parameter.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 3 figures
A Generic Explanation of the Mechanism of Co-solvency
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-14 20:00 EDT
Polymer behavior in mixed solvents often exhibits intriguing phenomena, such as cosolvency, where a polymer that collapses in two individually poor solvents becomes soluble in their mixture. In this study, we employ a combination of theoretical modeling and computer simulations using a generic polymer solution model to uncover the underlying mechanisms driving this behavior. Moving beyond conventional explanations based on solvent-cosolvent immiscibility or chemistry-specific interactions, our findings highlight the critical role of mismatches in solvophobicity and solvation strength between the polymer and the two solvent components. We demonstrate that co-solvency arises from the interplay between van der Waals interactions and specific associations, such as hydrogen bonding. The bulk phase behavior of the solution is also examined, and the resulting phase diagram, calculated using Flory-Huggins theory, shows good agreement with experimental observations. This study offers a generalized framework for understanding polymer cosolvency across diverse systems.
Soft Condensed Matter (cond-mat.soft)
Biharmonic-drive tunable Josephson diode
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-14 20:00 EDT
L. Borgongino, R. Seoane Souto, A. Paghi, G. Senesi, K. Skibinska, L. Sorba, F. Giazotto, E. Strambini
The superconducting diode effect has garnered significant interest due to its prospective applications in cryogenic electronics and computing, characterized by zero resistance and no energy dissipation. This phenomenon has been demonstrated across various superconducting platforms, which typically necessitate unconventional materials with broken spatial symmetries or external magnetic fields, posing scalability and integration challenges. This work introduces an innovative method to realize the superconducting diode effect by disrupting spatio-temporal symmetries in a conventional Josephson junction utilizing a biharmonic AC drive signal. We achieve wireless modulation of the diode’s polarity and efficiency with an antenna. Our findings indicate a diode efficiency reaching the ideal $ 100%$ over a broad frequency range, with a temperature resilience up to 800 mK, and efficient AC signal rectification. This versatile and platform-independent superconducting diode signifies a promising component for advancing future superconducting digital electronics, including efficient logic gates, ultra-fast switches, and dynamic half-wave supercurrent rectifiers.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
30 pages, 11 figures
Bloch transistor for cryogenic quantum electronics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Ilya Antonov, Rais Shaikhaidarov, Kyung Ho Kim, Dmitry Golubev, Sven Linzen, Evgeni V. Il’ichev, Vladimir N. Antonov, Oleg V. Astafiev
We report on the development of a Bloch transistor (BT) for the emerging platform of cryogenic quantum electronics. The BT is a fully quantum non-dissipative device facilitating precise delivery of the quantized current to the circuit, I=2efn (where n is an integer, e is the charge of an electron and f is the microwave frequency). It does not have an analogue in classical electronics, but it is required for quantum ones. The amplitude of the quantized current is adjustable through four controls: the gate or bias voltage and the frequency or amplitude of the microwave. The device features Josephson junctions operating in the regime of Bloch oscillations, an isolating electromagnetic circuit and microwave feeding leads. BT operates at a bias of 5 {\mu}V, and can deliver the quantized currents up to 10 nA.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
6 pages, 4 figures
Semimetallic two-dimensional defective graphene networks with periodic 4-8 defect lines
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Roland Gillen, Janina Maultzsch
We present theoretical simulations of the electronic properties of graphene-like two-dimensional (2D) carbon networks with a periodic arrangement of defect lines formed by alternating four- and eight-membered rings. These networks can be seen as arrays of armchair-edged nanoribbons (AGNRs), which are covalently connected at the edges. Using a combination of density functional theory and a simple tight binding model, we show that the electronic properties of these networks can be understood to arise from the family behaviour of the constituting AGNRs, plus a rigid shift due to an ‘inter-ribbon’ coupling across the defect lines. As a result, we find one class of zero-band-gap semiconducting 2D networks, and two classes of semimetallic networks with quasi-linear band close to the Fermi energy. The formation of closed-ring electron- and hole-like Fermi surfaces due to hybridization across the defect lines offers interesting perspectives of using such defective 2D networks for transport applications or the realization of carbon-based nodal line semimetals.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Preparation and coherent manipulation of toroidal moments in molecules
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-14 20:00 EDT
Kieran Hymas, Alessandro Soncini
Molecules with an odd number of electrons are expected to display paramagnetic behaviour in a uniform magnetic field. Instead, a vanishing magnetization is often measured in a family of lanthanide complexes known as Single Molecule Toroics. The anomaly can be explained in terms of degenerate quantum states in which electron spins and orbital currents give rise to time-odd and space-odd magnetic vortices known as toroidal moments, carrying a vanishing magnetic dipole. Resilient to stray magnetic fields and susceptible to electric manipulation, toroidal moments are sparking growing interest for applications in spintronics, magnonics, and photonics. While macroscopic toroidal moments have been observed in extended systems such as bulk low-dimensional non-collinear ferromagnets, theoretically predicted quantum toroidal states in molecules are yet to be observed, as it is currently unclear how to split degenerate states carrying counter-rotating vortices via existing experimental setups. Here we propose a realistic experimental protocol to polarize and observe molecular toroidal moments using pulsed microwave radiation. Modelling the spin-dynamics in a pulsed MW-field, we find that three resonant MW-pulses, delivered either sequentially or simultaneously, to a class of MDy$ _6$ (M = Al$ ^{3+}$ , Cr$ ^{3+}$ ) molecules consisting of coupled Dy$ _3$ toroidal moieties, can selectively and coherently transfer population to a long-lived polarized toroidal state. The ensuing magneto-electric properties can then be used as a read-out mechanism. Our results provide a strategy to measure and coherently manipulate toroidal states in molecular systems, which is expected to trigger applications of molecular toroidal states to quantum technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Designing Topological High-Order Van Hove Singularities: Twisted Bilayer Kagomé
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
David T. S. Perkins, Anirudh Chandrasekaran, Joseph J. Betouras
The interplay of high-order Van Hove singularities and topology plays a central role in determining the nature of the electronic correlations governing the phase of a system with unique signatures characterising their presence. Layered van der Waals heterostuctures are ideal systems for band engineering through the use of twisting and proximity effects. Here, we use symmetry to demonstrate how twisted Kagomé bilayers can host topological high-order Van Hove singularities. We study a commensurate system with a large twist angle and demonstrate how the initial choice of high-symmetry stacking order can greatly influence the electronic structure and topology of the system. We, furthermore, study the sublattice interference in the system. Our results illustrate the rich energy landscape of twisted Kagomé bilayers and unveil large Chern numbers (of order 10), establishing twisted bilayer Kagomé as a natural playground for probing the mixing of strong correlations and topology.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Main text: 12 pages, 5 figures. Supplemental Material: 14 pages, 12 figures
Shapiro resonances in ac-self-modulated exciton-polariton Josephson junctions
New Submission | Other Condensed Matter (cond-mat.other) | 2025-04-14 20:00 EDT
I. Carraro Haddad, D. L. Chafatinos, A. A. Reynoso, A. E. Bruchhausen, A. S. Kuznetsov, K. Biermann, P. V. Santos, G. Usaj, A. Fainstein
We experimentally investigate the dynamics of exciton polariton Josephson junctions when the coupling between condensates is periodically modulated through self-induced mechanical oscillations. The condensates energy detuning, the analog of the bias voltage in superconducting junctions, displays a plateau behavior akin to the Shapiro steps. At each step massive tunneling of particles occurs featuring Shapiro-like spikes. These characteristic changes are observed when the condensates Josephson frequency $ \omega_\textrm{J}$ is an integer multiple of the modulation frequency $ \omega_\mathrm{M}$ .
Other Condensed Matter (cond-mat.other)
8 pages, 3 figures
Emergent phases in the Yao-Lee model via coupling to topological spin textures
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-14 20:00 EDT
Electrons in metals experience an effective vector potential when coupled to spin textures with non-zero scalar spin chirality, such as skyrmions. This coupling can generate a substantial field, leading to pronounced observable phenomena, including the topological Hall effect. Motivated by this, we consider a bilayer model in which the Majorana fermions in the Yao-Lee model on one layer interact with topological spin textures on the second layer via a spin-spin interaction. Unlike the Kitaev model, the Yao-Lee model remains exactly solvable, allowing us to perform Monte Carlo simulations to determine its ground state. Our analysis indicates that skyrmion crystals can give rise to a variety of vison crystals that are periodic arrangements of the $ \mathbb{Z}_2$ fluxes with unusual patterns such as a kagome pattern. In addition, Majorana fermions acquire a substantial Berry phase from skyrmion crystals, resulting in phases with finite Chern numbers up to $ \nu =5$ . In the case of a single skyrmion defect in the magnetic layer, a corresponding defect in the vison configuration can be realized. These defects support localized states when the spin liquid is gapped. Similar to skyrmion crystals, spiral spin textures also give rise to a diverse range of flux crystals. However, in this case, most of these phases are gapless, with only a few being trivially-gapped. Our results highlight the rich physics emerging from the interplay between topological spin textures and fractionalized quasiparticles in quantum spin liquids.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
8 pages, 7 figures