CMP Journal 2025-02-14
Statistics
Nature Materials: 2
Nature Physics: 1
Nature Reviews Materials: 1
Science: 6
Physical Review Letters: 18
Physical Review X: 1
arXiv: 64
Nature Materials
Low-power 2D gate-all-around logics via epitaxial monolithic 3D integration
Original Paper | Electronic devices | 2025-02-13 19:00 EST
Junchuan Tang, Jianfeng Jiang, Xiaoyin Gao, Xin Gao, Chenxi Zhang, Mengdi Wang, Chengyuan Xue, Zhongrui Li, Yuling Yin, Congwei Tan, Feng Ding, Chenguang Qiu, Lian-Mao Peng, Hailin Peng
Innovations in device architectures and materials promote transistor miniaturization for improved performance, energy efficiency and integration density. At foreseeable ångström nodes, a gate-all-around (GAA) field-effect transistor based on two-dimensional (2D) semiconductors would provide excellent electrostatic gate controllability to achieve ultimate power scaling and performance delivering. However, a major roadblock lies in the scalable integration of 2D GAA heterostructures with atomically smooth and conformal interfaces. Here we report a wafer-scale multi-layer-stacked single-crystalline 2D GAA configuration achieved with low-temperature monolithic three-dimensional integration, in which high-mobility 2D semiconductor Bi2O2Se was epitaxially integrated by high-κ layered native-oxide dielectric Bi2SeO5 with an atomically smooth interface, enabling a high electron mobility of 280 cm2 V-1 s-1 and a near-ideal subthreshold swing of 62 mV dec-1. The scaled 2D GAA field-effect transistor with 30 nm gate length exhibits an ultralow operation voltage of 0.5 V, a high on-state current exceeding 1 mA μm-1, an ultralow intrinsic delay of 1.9 ps and an energy-delay product of 1.84 × 10-27 Js μm-1. This work demonstrates a wafer-scale 2D-material-based GAA system with valid performance and power merits, holding promising prospects for beyond-silicon monolithic three-dimensional circuits.
Electronic devices, Two-dimensional materials
Dielectric polymers with mechanical bonds for high-temperature capacitive energy storage
Original Paper | Materials for devices | 2025-02-13 19:00 EST
Rui Wang, Yujie Zhu, Shangshi Huang, Jing Fu, Yifan Zhou, Manxi Li, Li Meng, Xiyu Zhang, Jiajie Liang, Zhaoyu Ran, Mingcong Yang, Junluo Li, Xinhua Dong, Jun Hu, Jinliang He, Qi Li
High-temperature capacitive energy storage demands that dielectric materials maintain low electrical conduction loss and high discharged energy density under thermal extremes. The temperature capability of dielectric polymers is limited to below 200 °C, lagging behind requirements for high-power and harsh-condition electronics. Here we report a molecular topology design for dielectric polymers with mechanical bonds that overcomes this obstacle, where cyclic polyethers are threaded onto the axles of various polyimides. From density functional theory and molecular dynamics calculations, we found that the local vibrations of the encircled polymer chains were damped by the cyclic molecules through mechanical bonding, substantially inhibiting the phonon-assisted interchain charge transport that dominates conduction loss when approaching the thermal extremes. At 250 °C, we experimentally observed a d.c. electrical resistivity four orders of magnitude greater than that of commercial polyimides, with the discharged energy density reaching 4.1 J cm-3 with 90% charge-discharge efficiency, exceeding conventional dielectric polymers and polymer composites. These findings open up opportunities for substantially promoting the temperature capability of dielectric polymers given the rich diversity of existing molecular topologies modified with mechanical bonds.
Materials for devices, Materials for energy and catalysis
Nature Physics
Coulomb interactions and migrating Dirac cones imaged by local quantum oscillations in twisted graphene
Original Paper | Condensed-matter physics | 2025-02-13 19:00 EST
Matan Bocarsly, Indranil Roy, Vishal Bhardwaj, Matan Uzan, Patrick Ledwith, Gal Shavit, Nasrin Banu, Yaozhang Zhou, Yuri Myasoedov, Kenji Watanabe, Takashi Taniguchi, Yuval Oreg, Daniel E. Parker, Yuval Ronen, Eli Zeldov
Flat-band moiré graphene systems are a quintessential platform for investigating correlated phases of matter. Various interaction-driven ground states have been proposed, but despite extensive experimental effort, there has been little direct evidence that distinguishes between various phases, in particular near the charge neutrality point. Here we probe the fine details of the density of states and the effects of Coulomb interactions in alternating-twist trilayer graphene by imaging the local thermodynamic quantum oscillations with a nanoscale scanning superconducting quantum interference device. We find that the charging self-energy due to occupied electronic states is most important in explaining the high-carrier-density physics. At half-filling of the conduction flat band, we observe ferromagnetic-driven symmetry breaking, suggesting that it is the most robust mechanism in the hierarchy of phase transitions. Near charge neutrality, where exchange energy dominates over charging self-energy, we find a nematic semimetal ground state, which is theoretically favoured over gapped states in the presence of heterostrain. In this semimetallic phase, the flat-band Dirac cones migrate towards the mini-Brillouin zone centre, spontaneously breaking the threefold rotational symmetry. Our low-field local quantum oscillation technique can be used to explore the ground states of many strongly interacting van der Waals systems.
Condensed-matter physics, Ferromagnetism, Quantum mechanics, Topological matter
Nature Reviews Materials
Altermagnets as a new class of functional materials
Review Paper | Information storage | 2025-02-13 19:00 EST
Cheng Song, Hua Bai, Zhiyuan Zhou, Lei Han, Helena Reichlova, J. Hugo Dil, Junwei Liu, Xianzhe Chen, Feng Pan
Altermagnets are characterized by non-relativistic alternating spin splitting in the band structure and collinear compensated magnetic moments in real space. They combine the advantages of ferromagnetic and antiferromagnetic order, exhibiting time-reversal symmetry-breaking magneto responses, vanishing stray fields and high-frequency spin dynamics. Consequently, altermagnets hold great potential for various research fields, especially for developing spintronic devices such as high-density magnetic memories and terahertz nano-oscillators. Furthermore, altermagnetism is found in a broad spectrum of materials, including metals, semiconductors, insulators and superconductors, thereby stimulating widespread interest in functional material research. In this Perspective, we provide an overview of recent experimental progress in altermagnets, focusing particularly on observations of lifted spin degeneracy via spectroscopic techniques and the resultant spin transport phenomena. Additionally, we discuss future research directions in altermagnets, encompassing fields such as spintronics, magnonics, ultrafast photonics and phononics, and properties such as superconductivity, topology and multiferroicity.
Information storage, Magnetic properties and materials, Spintronics
Science
Evolutionary convergence of sensory circuits in the pallium of amniotes
Research Article | Brain evolution | 2025-02-14 03:00 EST
Eneritz Rueda-Alaña, Rodrigo Senovilla-Ganzo, Marco Grillo, Enrique Vázquez, Sergio Marco-Salas, Tatiana Gallego-Flores, Aitor Ordeñana-Manso, Artemis Ftara, Laura Escobar, Alberto Benguría, Ana Quintas, Ana Dopazo, Miriam Rábano, María dM Vivanco, Ana María Aransay, Daniel Garrigos, Ángel Toval, José Luis Ferrán, Mats Nilsson, Juan Manuel Encinas-Pérez, Maurizio De Pittà, Fernando García-Moreno
The amniote pallium contains sensory circuits that are structurally and functionally equivalent, yet their evolutionary relationship remains unresolved. We used birthdating analysis, single-cell RNA and spatial transcriptomics, and mathematical modeling to compare the development and evolution of known pallial circuits across birds (chick), lizards (gecko), and mammals (mouse). We reveal that neurons within these circuits' stations are generated at varying developmental times and brain regions across species and found an early developmental divergence in the transcriptomic progression of glutamatergic neurons. Our research highlights developmental distinctions and functional similarities in the sensory circuit between birds and mammals, suggesting the convergence of high-order sensory processing across amniote lineages.
Developmental origins and evolution of pallial cell types and structures in birds
Research Article | Brain evolution | 2025-02-14 03:00 EST
Bastienne Zaremba, Amir Fallahshahroudi, Céline Schneider, Julia Schmidt, Ioannis Sarropoulos, Evgeny Leushkin, Bianka Berki, Enya Van Poucke, Per Jensen, Rodrigo Senovilla-Ganzo, Francisca Hervas-Sotomayor, Nils Trost, Francesco Lamanna, Mari Sepp, Fernando García-Moreno, Henrik Kaessmann
Innovations in the pallium likely facilitated the evolution of advanced cognitive abilities in birds. We therefore scrutinized its cellular composition and evolution using cell type atlases from chicken, mouse, and nonavian reptiles. We found that the avian pallium shares most inhibitory neuron types with other amniotes. Whereas excitatory neuron types in amniote hippocampal regions show evolutionary conservation, those in other pallial regions have diverged. Neurons in the avian mesopallium display gene expression profiles akin to the mammalian claustrum and deep cortical layers, while certain nidopallial cell types resemble neurons in the piriform cortex. Lastly, we observed substantial gene expression convergence between the dorsally located hyperpallium and ventrally located nidopallium during late development, suggesting that topological location does not always dictate gene expression programs determining functional properties in the adult avian pallium.
KLF2 maintains lineage fidelity and suppresses CD8 T cell exhaustion during acute LCMV infection
Research Article | Immunology | 2025-02-14 03:00 EST
Eric Fagerberg, John Attanasio, Christine Dien, Jaiveer Singh, Emily A. Kessler, Leena Abdullah, Jian Shen, Brian G. Hunt, Kelli A. Connolly, Edward De Brouwer, Jiaming He, Nivedita R. Iyer, Jessica Buck, Emily R. Borr, Martina Damo, Gena G. Foster, Josephine R. Giles, Yina H. Huang, John S. Tsang, Smita Krishnaswamy, Weiguo Cui, Nikhil S. Joshi
Naïve CD8 T cells have the potential to differentiate into a spectrum of functional states during an immune response. How these developmental decisions are made and what mechanisms exist to suppress differentiation toward alternative fates remains unclear. We employed in vivo CRISPR-Cas9-based perturbation sequencing to assess the role of ~40 transcription factors (TFs) and epigenetic modulators in T cell fate decisions. Unexpectedly, we found that knockout of the TF Klf2 resulted in aberrant differentiation to exhausted-like CD8 T cells during acute infection. KLF2 was required to suppress the exhaustion-promoting TF TOX and to enable the TF TBET to drive effector differentiation. KLF2 was also necessary to maintain a polyfunctional tumor-specific progenitor state. Thus, KLF2 provides effector CD8 T cell lineage fidelity and suppresses the exhaustion program.
Conformational ensembles reveal the origins of serine protease catalysis
Research Article | Enzymology | 2025-02-14 03:00 EST
Siyuan Du, Rachael C. Kretsch, Jacob Parres-Gold, Elisa Pieri, Vinícius Wilian D. Cruzeiro, Mingning Zhu, Margaux M. Pinney, Filip Yabukarski, Jason P. Schwans, Todd J. Martínez, Daniel Herschlag
Enzymes exist in ensembles of states that encode the energetics underlying their catalysis. Conformational ensembles built from 1231 structures of 17 serine proteases revealed atomic-level changes across their reaction states. By comparing the enzymatic and solution reaction, we identified molecular features that provide catalysis and quantified their energetic contributions to catalysis. Serine proteases precisely position their reactants in destabilized conformers, creating a downhill energetic gradient that selectively favors the motions required for reaction while limiting off-pathway conformational states. The same catalytic features have repeatedly evolved in proteases and additional enzymes across multiple distinct structural folds. Our ensemble-function analyses revealed previously unknown catalytic features, provided quantitative models based on simple physical and chemical principles, and identified motifs recurrent in nature that may inspire enzyme design.
Enhancer-driven cell type comparison reveals similarities between the mammalian and bird pallium
Research Article | Brain evolution | 2025-02-14 03:00 EST
Nikolai Hecker, Niklas Kempynck, David Mauduit, Darina Abaffyová, Roel Vandepoel, Sam Dieltiens, Lars Borm, Ioannis Sarropoulos, Carmen Bravo González-Blas, Julie De Man, Kristofer Davie, Elke Leysen, Jeroen Vandensteen, Rani Moors, Gert Hulselmans, Lynette Lim, Joris De Wit, Valerie Christiaens, Suresh Poovathingal, Stein Aerts
Combinations of transcription factors govern the identity of cell types, which is reflected by genomic enhancer codes. We used deep learning to characterize these enhancer codes and devised three metrics to compare cell types in the telencephalon across amniotes. To this end, we generated single-cell multiome and spatially resolved transcriptomics data of the chicken telencephalon. Enhancer codes of orthologous nonneuronal and γ-aminobutyric acid-mediated (GABAergic) cell types show a high degree of similarity across amniotes, whereas excitatory neurons of the mammalian neocortex and avian pallium exhibit varying degrees of similarity. Enhancer codes of avian mesopallial neurons are most similar to those of mammalian deep-layer neurons. With this study, we present generally applicable deep learning approaches to characterize and compare cell types on the basis of genomic regulatory sequences.
Neuroevolution insights into biological neural computation
Review | Neuroscience | 2025-02-14 03:00 EST
Risto Miikkulainen
This article reviews existing work and future opportunities in neuroevolution, an area of machine learning in which evolutionary optimization methods such as genetic algorithms are used to construct neural networks to achieve desired behavior. The article takes a neuroscience perspective, identifying where neuroevolution can lead to insights about the structure, function, and developmental and evolutionary origins of biological neural circuitry that can be studied in further neuroscience experiments. It proposes optimization under environmental constraints as a unifying theme and suggests the evolution of language as a grand challenge whose time may have come.
Physical Review Letters
Neural-Network-Based Design of Approximate Gottesman-Kitaev-Preskill Code
Research article | Machine learning | 2025-02-14 05:00 EST
Yexiong Zeng, Wei Qin, Ye-Hong Chen, Clemens Gneiting, and Franco Nori
Gottesman-Kitaev-Preskill (GKP) encoding holds promise for continuous-variable fault-tolerant quantum computing. While an ideal GKP encoding is abstract and impractical due to its nonphysical nature, approximate versions provide viable alternatives. Conventional approximate GKP codewords are superpositions of multiple large-amplitude squeezed coherent states. This feature ensures correctability against single-photon loss and dephasing at short times, but also increases the difficulty of preparing the codewords. To minimize this tradeoff, we utilize a neural network to generate optimal approximate GKP states, allowing effective error correction with just a few squeezed coherent states. We find that such optimized GKP codes outperform the best conventional ones, requiring fewer squeezed coherent states, while maintaining simple and generalized stabilizer operators. Specifically, the former outperform the latter with just one-third of the number of squeezed coherent states at a squeezing level of 9.55 dB. This optimization drastically decreases the complexity of codewords while improving error correctability.
Phys. Rev. Lett. 134, 060601 (2025)
Machine learning, Open quantum systems & decoherence, Optical quantum information processing, Quantum error correction, Quantum optics, Quantum cavities, Artificial neural networks, Lindblad equation
Observation of the Two-Photon Landau-Zener-St"uckelberg-Majorana Effect
Research article | Quantum circuits | 2025-02-14 05:00 EST
Isak Björkman, Marko Kuzmanović, and Gheorghe Sorin Paraoanu
Harnessing second-order processes enables new control schemes in quantum dynamics. We show that the Landau-Zener-St"uckelberg-Majorana (LZSM) transition can be generalized to a virtual-state process in a three-level system, employing a phase modulated drive whereby two photons excite the system from the first to the third level while avoiding the second one. We implement experimentally this process in a transmon, achieving 98% population transfer. We predict and observe the doubling of LZSM velocity. Furthermore, we demonstrate robustness to amplitude and frequency offsets, made possible by the nearly exact cancellation of the two-photon ac Stark shift due to the presence of the fourth state.
Phys. Rev. Lett. 134, 060602 (2025)
Quantum circuits, Quantum computation, Quantum control
Ultrahigh-Energy Particle Collisions and Heavy Dark Matter at Phase Transitions
Research article | Dark matter | 2025-02-14 05:00 EST
Iason Baldes, Maximilian Dichtl, Yann Gouttenoire, and Filippo Sala
We initiate the study of ''bubbletrons,'' by which we mean ultrahigh-energy collisions of the particle shells that generically form at the walls of relativistic bubbles in cosmological first-order phase transitions (PT). As an application, we calculate the maximal dark matter mass \({M}_{\mathrm{DM}}\) that bubbletrons can produce in a \(U(1)\) gauge PT, finding \({M}_{\mathrm{DM}}\sim {10}^{5}/{10}^{11}/{10}^{15}\text{ }\text{ }\mathrm{GeV}\) for PT scales \({v}_{\phi }\sim {10}^{- 2}/{10}^{3}/{10}^{9}\text{ }\text{ }\mathrm{GeV}\). Bubbletrons realize a novel link between ultrahigh-energy phenomena and gravitational waves sourced at the PT, from nanohertz to megahertz frequencies.
Phys. Rev. Lett. 134, 061001 (2025)
Dark matter, First order phase transitions, Gravitational waves
Nuclear Recoil Calibration at Sub-keV Energies in LUX and Its Impact on Dark Matter Search Sensitivity
Research article | Electronic excitation & ionization | 2025-02-14 05:00 EST
D. S. Akerib et al.
Dual-phase xenon time projection chamber (TPC) detectors offer heightened sensitivities for dark matter detection across a spectrum of particle masses. To broaden their capability to low-mass dark matter interactions, we investigated the light and charge responses of liquid xenon (LXe) to sub-keV nuclear recoils. Using neutron events from a pulsed Adelphi Deuterium-Deuterium neutron generator, an in situ calibration was conducted on the LUX detector. We demonstrate direct measurements of light and charge yields down to 0.45 and 0.27 keV, respectively, both approaching single quanta production, the physical limit of LXe detectors. These results hold significant implications for the future of dual-phase xenon TPCs in detecting low-mass dark matter via nuclear recoils.
Phys. Rev. Lett. 134, 061002 (2025)
Electronic excitation & ionization, Particle dark matter, Dark matter detectors
Quadratic Quasinormal Mode Dependence on Linear Mode Parity
Research article | General relativity | 2025-02-14 05:00 EST
Patrick Bourg, Rodrigo Panosso Macedo, Andrew Spiers, Benjamin Leather, Béatrice Bonga, and Adam Pound
Quasinormal modes (QNMs) uniquely describe the dominant piece of the gravitational-wave ringdown of postmerger black holes. While the linear QNM regime has been extensively studied, recent work has highlighted the importance of second-perturbative-order, quadratic QNMs (QQNMs) arising from the nonlinear coupling of linear QNMs. Previous attempts to quantify the magnitude of these QQNMs have shown discrepant results. Using a new hyperboloidal framework, we resolve the discrepancy by showing that the QQNM/QNM ratio is a function not only of the black hole parameters but also of the ratio between even- and odd-parity linear QNMs: the ratio QQNM/QNM depends on what created the ringing black hole, but only through this ratio of even- to odd-parity linear perturbations.
Phys. Rev. Lett. 134, 061401 (2025)
General relativity, Gravitational waves
Search for Magnetic Monopole Pair Production in Ultraperipheral \(\mathrm{Pb}+\mathrm{Pb}\) Collisions at \(\sqrt{ {s}_{\mathrm{NN}}}=5.36\text{ }\text{ }\mathrm{TeV}\) with the ATLAS Detector at the LHC
Research article | Particle production | 2025-02-14 05:00 EST
G. Aad et al. (ATLAS Collaboration)
This Letter presents a search for highly ionizing magnetic monopoles in \(262\text{ }\text{ }\mathrm{\mu }{\mathrm{b}}^{- 1}\) of ultraperipheral \(\mathrm{Pb}+\mathrm{Pb}\) collision data at \(\sqrt{ {s}_{\mathrm{NN}}}=5.36\text{ }\text{ }\mathrm{TeV}\) collected by the ATLAS detector at the LHC. A new methodology that exploits the properties of clusters of hits reconstructed in the innermost silicon detector layers is introduced to study highly ionizing particles in heavy-ion data. No significant excess above the background, which is estimated using a data-driven technique, is observed. Using a nonperturbative semiclassical model, upper limits at 95% confidence level are set on the cross section for pair production of monopoles with a single Dirac magnetic charge in the mass range of 20--150 GeV. Depending on the model, monopoles with a single Dirac magnetic charge and mass below 80--120 GeV are excluded.
Phys. Rev. Lett. 134, 061803 (2025)
Particle production, Quantum electrodynamics, Hypothetical particles, Magnetic monopoles
Fragmentation of the Giant Pairing Vibration in \(^{14}\mathrm{C}\) Induced by Many-Body Processes
Research article | Nuclear many-body theory | 2025-02-14 05:00 EST
F. Barranco, G. Potel, and E. Vigezzi
We present a theoretical framework for treating the full excitation spectrum of \({J}^{\pi }={0}^{+}\) pair addition modes, including the well-known low-lying and bound pairing vibrations on par with the predicted high-lying pairing vibrations, often called giant pairing vibrations. Our formalism includes the coupling to low-energy collective quadrupolar modes of the core, in such a way that both single-particle self-energy effects and the pairing interaction induced by phonon exchange are accounted for. The coupling with the continuum plays an important role and is also taken into account. The theory is applied to the case of the excitation spectrum of \(^{14}\mathrm{C}\), recently populated by two-neutron transfer reactions.
Phys. Rev. Lett. 134, 062501 (2025)
Nuclear many-body theory, Nuclear structure & decays
Deformation and Collectivity in Doubly Magic \(^{208}\mathrm{Pb}\)
Research article | Electromagnetic transitions | 2025-02-14 05:00 EST
J. Henderson et al.
Lead-208 is the heaviest known doubly magic nucleus and its structure is therefore of special interest. Despite this magicity, which acts to provide a strong restorative force toward sphericity, it is known to exhibit both strong octupole correlations and some of the strongest quadrupole collectivity observed in doubly magic systems. In this Letter, we employ state-of-the-art experimental equipment to conclusively demonstrate, through four Coulomb-excitation measurements, the presence of a large, negative, spectroscopic quadrupole moment for both the vibrational octupole \({3}_{1}^{- }\) and quadrupole \({2}_{1}^{+}\) state, indicative of a preference for prolate deformation of the states. The observed quadrupole moment is discussed in the context of the expected splitting of the \({3}^{- }\bigotimes {3}^{- }\) two-phonon states, due to the coupling of the quadrupole and octupole motion. These results are compared with theoretical values from three different methods, which are unable to reproduce both the sign and magnitude of this deformation. Thus, in spite of its well-studied nature, \(^{208}\mathrm{Pb}\) remains a puzzle for our understanding of nuclear structure.
Phys. Rev. Lett. 134, 062502 (2025)
Electromagnetic transitions, Nuclear shapes and moments, Spectroscopic factors & electromagnetic moments
Direct Mass Measurements of Neutron-Rich Zinc and Gallium Isotopes: An Investigation of the Formation of the First \(r\)-Process Peak
Research article | Binding energy & masses | 2025-02-14 05:00 EST
Andrew Jacobs et al.
The prediction of isotopic abundances resulting from the rapid neutron capture process (\(r\) process) requires high-precision mass measurements. Using TITAN's on-line time-of-flight spectrometer, first time mass measurements are performed for \(^{83}\mathrm{Zn}\) and \(^{86}\mathrm{Ga}\). These measurements reduced uncertainties, and are used to calculate isotopic abundances near the first \(r\)-process abundance peak using astrophysical conditions present during a binary neutron star (BNS) merger. Good agreement in abundance across a range of trajectories is found when comparing to several metal-poor stars while also strongly deviating from the solar \(r\)-process pattern. These findings point to a high degree of sensitivity to the electron fraction of a BNS merger on the final elemental abundance pattern for certain elements near the first \(r\)-process peak while others display universality. We find that small changes in electron fraction can produce distinct abundance patterns that match those of metal-poor stars with different classifications.
Phys. Rev. Lett. 134, 062701 (2025)
Binding energy & masses, Nuclear astrophysics, Rare & new isotopes, 59 ≤ A ≤ 89, Radioactive beams, Spectrometers & spectroscopic techniques
Fully Programmable Spatial Photonic Ising Machine by Focal Plane Division
Research article | Neuromorphic computing | 2025-02-14 05:00 EST
Daniele Veraldi, Davide Pierangeli, Silvia Gentilini, Marcello Calvanese Strinati, Jason Sakellariou, James S. Cummins, Airat Kamaletdinov, Marvin Syed, Richard Zhipeng Wang, Natalia G. Berloff, Dimitrios Karanikolopoulos, Pavlos G. Savvidis, and Claudio Conti
Ising machines are an emerging class of hardware that promises ultrafast and energy-efficient solutions to \(NP\)-hard combinatorial optimization problems. Spatial photonic Ising machines (SPIMs) exploit optical computing in free space to accelerate the computation, showcasing parallelism, scalability, and low power consumption. However, current SPIMs can implement only a restricted class of problems. This partial programmability is a critical limitation that hampers their benchmark. Achieving full programmability of the device while preserving its scalability is an open challenge. Here, we report a fully programmable SPIM achieved through a novel operation method based on the division of the focal plane. In our scheme, a general Ising problem is decomposed into a set of Mattis Hamiltonians, whose energies are simultaneously computed optically by measuring the intensity on different regions of the camera sensor. Exploiting this concept, we experimentally demonstrate the computation with high success probability of ground-state solutions of up to 32-spin Ising models on unweighted maximum cut graphs with and without ferromagnetic bias. Simulations of the hardware prove a favorable scaling of the accuracy with the number of spin. Our fully programmable SPIM enables the implementation of many quadratic unconstrained binary optimization problems, further establishing SPIMs as a leading paradigm in non--von Neumann hardware.
Phys. Rev. Lett. 134, 063802 (2025)
Neuromorphic computing, Optical computing, Optimization problems, Photonics, Spatial light modulators, Imaging & optical processing, Ising model, Simulated annealing
Bulk-Hole Correspondence and Inner Robust Boundary Modes in Singular Flatband Lattices
Research article | Photonics | 2025-02-14 05:00 EST
Limin Song, Shenyi Gao, Shiqi Xia, Yongsheng Liang, Liqin Tang, Daohong Song, Daniel Leykam, and Zhigang Chen
Topological entities based on bulk-boundary correspondence are ubiquitous, from conventional to higher-order topological insulators, where the protected states are typically localized at the outer boundaries (edges or corners). A less explored scenario involves protected states that are localized at the inner boundaries, sharing the same energy as the bulk states. Here, we propose and demonstrate what we refer to as the ''bulk-hole correspondence''---a relation between the inner robust boundary modes (RBMs) and the existence of multiple ''holes'' in singular flatband lattices, mediated by the immovable discontinuity of the bulk Bloch wave functions. We find that the number of independent flatband states always equals the sum of the number of independent compact localized states and the number of nontrivial inner RBMs, as captured by the Betti number that also counts the hole number from topological data analysis. This correspondence is universal for singular flatband lattices, regardless of the lattice shape and the hole shape. Using laser-written kagome lattices as a platform, we experimentally observe such inner RBMs, demonstrating their real-space topological nature and robustness. Our results may extend to other singular flatband systems beyond photonics, including non-Euclidean lattices, providing a new approach for understanding nontrivial flatband states and topology in hole-bearing lattice systems.
Phys. Rev. Lett. 134, 063803 (2025)
Photonics
Water Nanofilms Facilitate Ice Crystal Growth across Droplets
Research article | Drop & bubble phenomena | 2025-02-14 05:00 EST
Shaojie Hu, Ningning Zhao, Chao Zhang, Fuxiang Li, Renpeng Chen, and Dani Or
A novel mechanism that underlies the peculiar cascading freezing of multiple supercooled droplets on surfaces is reported. The initial ice crystal growth in large droplets is communicated via connected water nanofilms to smaller droplets. Using high-speed imaging, we show that the presence of a water nanofilm with thickness higher than a critical value around 4.5 nm facilitates a freezing front propagation from one droplet to its neighbors on a hydrophilic surface. The freezing propagation rate through water nanofilms is approximately 40% of the recalescence front growth rate within a droplet, both of which are well described by kinetic crystal growth theory.
Phys. Rev. Lett. 134, 064001 (2025)
Drop & bubble phenomena, Drops & bubbles, Phase transitions, Ice, Water
Spectroscopic Evidence for Possible Quantum Spin Liquid Behavior in a Two-Dimensional Mott Insulator
Research article | Electronic structure | 2025-02-14 05:00 EST
Haiyang Chen, Fo-Hong Wang, Qiang Gao, Xue-Jian Gao, Zhenhua Chen, Yaobo Huang, Kam Tuen Law, Xiao Yan Xu, and Peng Chen
Mott insulators with localized magnetic moments will exhibit a quantum spin liquid state when the quantum fluctuations are strong enough to suppress the ordering of the spins. Such an entangled state will give rise to collective excitations, in which spin and charge information are carried separately. Our angle-resolved photoemission spectroscopy measurements on single-layer \(1T\text{- }{\mathrm{TaS}}_{2}\) show a flat band around the zone center and a gap opening of about 200 meV in the low temperature, indicating 2D Mott insulating nature in the system. This flat band is dispersionless in momentum space but shows anomalously broad width around the zone center and the spectral weight decays rapidly as momentum increases. The observation is described as a spectral continuum from electron fractionalization, corroborated by a low energy effective model. The intensity of the flat band is reduced by surface doping with magnetic adatoms and the gap is closing, a result from the interaction between spin impurities coupled with spinons and the chargons, which gives rise to a charge redistribution. Doping with nonmagnetic impurities behaves differently as the chemical potential shift dominates. These findings provide insight into the quantum spin liquid states of strongly correlated electrons on 2D triangular lattices.
Phys. Rev. Lett. 134, 066402 (2025)
Electronic structure, Quantum spin liquid, Mott insulators, Thin films, Transition metal dichalcogenides, Angle-resolved photoemission spectroscopy, Molecular beam epitaxy
Mechanism of Type-II Multiferroicity in Pure and Al-Doped \({\mathrm{CuFeO}}_{2}\)
Research article | Doping effects | 2025-02-14 05:00 EST
Weiqin Zhu, Panshuo Wang, Haoran Zhu, Haiyan Zhu, Xueyang Li, Jun Zhao, Changsong Xu, and Hongjun Xiang
Type-II multiferroicity, where electric polarization is induced by specific spin patterns, is crucial in fundamental physics and advanced spintronics. However, the spin model and magnetoelectric coupling mechanisms in prototypical type-II multiferroic \({\mathrm{CuFeO}}_{2}\) and Al-doped \({\mathrm{CuFeO}}_{2}\) remain unclear. Here, by considering both spin and alloy degrees of freedom, we develop a magnetic cluster expansion method, which considers all symmetry allowed interactions. Applying such method, we not only obtain realistic spin model that can correctly reproduce observations for both \({\mathrm{CuFeO}}_{2}\) and \({\mathrm{CuFe}}_{1- x}{\mathrm{Al}}_{x}{\mathrm{O}}_{2}\), but also revisit well-known theories of the original spin-current (SC) model and \(p\text{- }d\) hybridization model. Specifically, we find that (i) a previously overlooked biquadratic interaction is critical to reproduce the $$ ground state and excited states of \({\mathrm{CuFeO}}_{2}\); (ii) the combination of absent biquadratic interaction and increased magnetic frustration around Al dopants stabilizes the proper screw state; and (iii) it is the generalized spin-current (GSC) model that can correctly characterize the multiferroicity of \({\mathrm{CuFeO}}_{2}\). These findings have broader implications for understanding novel magnetoelectric couplings in, e.g., monolayer multiferroic \({\mathrm{NiI}}_{2}\).
Phys. Rev. Lett. 134, 066801 (2025)
Doping effects, Electric polarization, Frustrated magnetism, Multiferroics, Noncollinear magnets, Density functional theory, Machine learning, Monte Carlo methods
Extending Rytov Approximation to Vector Waves for Tomography of Anisotropic Materials
Research article | Polarization of light | 2025-02-14 05:00 EST
ChulMin Oh, Herve Hugonnet, Juheon Lee, and YongKeun Park
Liquid crystal phases exhibit distinctive properties due to their unique molecular ordering, making them central to materials science and soft matter physics. Their orientational ordering induces birefringence, which can be detected by optical microscopy. However, the analysis of 3D orientation, material distribution, and anisotropy from scattered light poses significant challenges due to the vector nature of the light-matter interaction. In this study, we formulate a scattering theory based on the Rytov approximation, commonly employed in scalar wave tomography, tailored to accommodate vector waves by modifying the scattering matrix. Using this formulation, we reveal the intricate 3D structure of liquid crystals with multiple topological defects. Specifically, we visualize the 3D structures of topological defects that were indistinguishable using conventional 2D imaging methods.
Phys. Rev. Lett. 134, 068101 (2025)
Polarization of light, Tomography, Wave scattering, Liquid crystals, Elastic wave theory, Electromagnetic wave theory
Phase Separation, Capillarity, and Odd-Surface Flows in Chiral Active Matter
Research article | Active Brownian particles | 2025-02-14 05:00 EST
Luke Langford and Ahmad K. Omar
Active phase separations evade canonical thermodynamic descriptions and have thus challenged our understanding of coexistence and interfacial phenomena. Considerable progress has been made towards a nonequilibrium theoretical description of these traditionally thermodynamic concepts. Spatial parity symmetry is conspicuously assumed in much of this progress, despite the ubiquity of chirality in experimentally realized systems. In this Letter, we derive a theory for the phase coexistence and interfacial fluctuations of a system that microscopically violates spatial parity. We find suppression of the phase separation as chirality is increased as well as the development of steady-state currents tangential to the interface dividing the phases. These odd flows are irrelevant to stationary interfacial properties, with stability, capillary fluctuations, and surface area minimization determined entirely by the capillary surface tension. Using large-scale Brownian dynamics simulations, we find excellent agreement with our theoretical scaling predictions.
Phys. Rev. Lett. 134, 068301 (2025)
Active Brownian particles, Interfaces, Living matter & active matter, Chiral symmetry
Nonequilibrium Transitions in a Template Copying Ensemble
Research article | Biomolecular processes | 2025-02-14 05:00 EST
Arthur Genthon, Carl D. Modes, Frank Jülicher, and Stephan W. Grill
The fuel-driven process of replication in living systems generates distributions of copied entities with varying degrees of copying accuracy. Here we introduce a thermodynamically consistent ensemble for investigating universal population features of template copying systems. In the context of copolymer copying, coarse-graining over molecular details, we establish a phase diagram of copying accuracy. We discover sharp non-equilibrium transitions between populations of random and accurate copies. Maintaining a population of accurate copies requires a minimum energy expenditure that depends on the configurational entropy of copolymer sequences.
Phys. Rev. Lett. 134, 068402 (2025)
Biomolecular processes, Emergent biological functions from complex interactions, Phase transitions in biological systems, Replication, Stochastic processes, DNA, Nonequilibrium systems, Stochastic dynamical systems
Excitation-Inhibition Balance Controls Information Encoding in Neural Populations
Research article | Neural information | 2025-02-14 05:00 EST
Giacomo Barzon, Daniel Maria Busiello, and Giorgio Nicoletti
Understanding how the complex connectivity structure of the brain shapes its information-processing capabilities is a long-standing question. By focusing on a paradigmatic architecture, we study how the neural activity of excitatory and inhibitory populations encodes information on external signals. We show that at long times information is maximized at the edge of stability, where inhibition balances excitation, both in linear and nonlinear regimes. In the presence of multiple external signals, this maximum corresponds to the entropy of the input dynamics. By analyzing the case of a prolonged stimulus, we find that stronger inhibition is instead needed to maximize the instantaneous sensitivity, revealing an intrinsic tradeoff between short-time responses and long-time accuracy. In agreement with recent experimental findings, our results pave the way for a deeper information-theoretic understanding of how the balance between excitation and inhibition controls optimal information-processing in neural populations.
Phys. Rev. Lett. 134, 068403 (2025)
Neural information, Neuronal dynamics, Stochastic processes, Neuronal network activity, Information theory, Langevin equation
Physical Review X
Photon-Counting Interferometry to Detect Geontropic Space-Time Fluctuations with GQuEST
Research article | Experimental studies of gravity | 2025-02-14 05:00 EST
Sander M. Vermeulen, Torrey Cullen, Daniel Grass, Ian A. O. MacMillan, Alexander J. Ramirez, Jeffrey Wack, Boris Korzh, Vincent S. H. Lee, Kathryn M. Zurek, Chris Stoughton, and Lee McCuller
Predictions of theories that combine quantum mechanics with gravity could be observed using highly sensitive photon detection in a tabletop experiment.
Phys. Rev. X 15, 011034 (2025)
Experimental studies of gravity, Nonclassical interferometry, Quantum fluctuations & noise, Quantum gravity, Quantum metrology, Gravitational wave detectors, Optical interferometry, Photon counting, Single-photon detectors
arXiv
The Saga of \(α\)-RuCl\(_3\): Parameters, Models, and Phase Diagrams
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
Marius Möller, P. A. Maksimov, Shengtao Jiang, Steven R. White, Roser Valenti, A. L. Chernyshev
RuCl\(_3\) was likely the first ever deliberately synthesized ruthenium compound, following the discovery of the \(_{44}\)Ru element in 1844. For a long time it was known as an oxidation catalyst, with its physical properties being discrepant and confusing, until a decade ago when its allotropic form \(\alpha\)-RuCl\(_3\) rose to exceptional prominence. This "re-discovery" of \(\alpha\)-RuCl\(_3\) has not only reshaped the hunt for a material manifestation of the Kitaev spin liquid, but it has opened the floodgates of theoretical and experimental research in the many unusual phases and excitations that the anisotropic-exchange magnets as a class of compounds have to offer. Given its importance for the field of Kitaev materials, it is astonishing that the low-energy spin model that describes this compound and its possible proximity to the much-desired spin-liquid state is still a subject of significant debate ten years later. In the present study, we argue that the existing key phenomenological observations put strong natural constraints on the effective microscopic spin model of \(\alpha\)-RuCl\(_3\), and specifically on its spin-orbit-induced anisotropic-exchange parameters that are responsible for the non-trivial physical properties of this material. These constraints allow one to focus on the relevant region of the multi-dimensional phase diagram of the \(\alpha\)-RuCl\(_3\) model, suggest an intuitive description of it via a different parametrization of the exchange matrix, offer a unifying view on the earlier assessments of its parameters, and bring closer together several approaches to the derivation of anisotropic-exchange models. We explore extended phase diagrams relevant to the \(\alpha\)-RuCl\(_3\) parameter space using quasi-classical, Luttinger-Tisza, exact diagonalization, and density-matrix renormalization group methods, demonstrating a remarkably c... (arxiv cutoff; for the rest, see the paper)
Strongly Correlated Electrons (cond-mat.str-el)
39 pages, 28 Figures. Text of immense pedagogical power
Extended strange metal regime from superconducting puddles
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
Noga Bashan, Evyatar Tulipman, Steven A. Kivelson, Jörg Schmalian, Erez Berg
We study a model of mesoscale superconducting puddles in a metal, represented as dynamical impurities interacting with a finite number of electronic channels via Andreev and normal scattering. We identify conditions under which the collection of puddles make a \(T\)-linear contribution to the resistivity and a \(T\ln(1/T)\) to the specific heat and thermopower. This behavior emerges in an intermediate temperature range that extends from an upper energy scale set by the renormalized charging energy of the puddles, and down to an exponentially small scale associated with a charge-Kondo crossover, provided that the number of electronic channels interacting with the puddle is large. The phenomenology of our model resembles the apparent extended strange metal regime observed in overdoped cuprates which exhibits \(T\)-linear resistivity at low \(T\) over a finite range of doping. We also propose to engineer a strange metal from suitably designed superconducting grains in a metallic matrix.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
7+14 pages, 3+5 figures
Kekulé Spiral Order from Strained Topological Heavy Fermions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
Jonah Herzog-Arbeitman, Dumitru Călugăru, Haoyu Hu, Jiabin Yu, Nicolas Regnault, Jian Kang, B. Andrei Bernevig, Oskar Vafek
The topological heavy fermion (THF) model of twisted bilayer graphene is a framework for treating its strongly interacting topological flat bands. In this work, we employ the THF model with heterostrain and particle-hole symmetry breaking corrections to study its symmetry-broken ground states. We find that the heterostrain correction motivates a specific parent-state wavefunction which dictates the presence or absence of an incommensurate Kekulé spiral (IKS) at each integer filling by invoking Dirac node braiding and annihilation as a mechanism to achieve low energy gapped states. We then show that one-shot Hartree-Fock faithfully replicates the numerical results of fully self-consistent states and motivates an analytical approximation for the IKS wavevector. We can also account for the particle-hole asymmetry in the correlated insulator gaps. In particular, the THF model predicts stronger correlated states on the electron side rather than hole side in agreement with magic angle experiments, despite the electron side being more dispersive in the single-particle band structure. This work demonstrates that we can analytically explain even the more subtle symmetry breaking order properties observed in experiments where heterostrain, relaxation, and interactions together determine the ground state.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Absorbing state transitions with discrete symmetries
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Hyunsoo Ha, David A. Huse, Rhine Samajdar
Recent progress in interactive quantum dynamics has inspired the study of fundamentally out-of-equilibrium dynamical phase transitions of quantum and classical many-body systems. Motivated by these developments, we study nonequilibrium phase transitions to absorbing states in one-dimensional systems that can model certain quantum circuits. Specifically, we consider dynamics for which the absorbing states are not unique due to a discrete symmetry: Z2 for two-state models and S3 or Z3 for three-state models. Under time evolution, domain walls in these models perform random walks and coarsen under local feedback, which, if perfect, reduces their number over time, driving the system to an absorbing state in polynomial time. Imperfect feedback, however, introduces domain wall multiplication (branching), potentially leading to an active phase. For Z2-symmetric two-state models, starting from a single domain wall, we find distinct absorbing and active phases as in previous studies. Extending this analysis to local three-state models shows that any nonzero branching rate drives the system into the active phase. However, we demonstrate that incorporating nonlocal classical information into the feedback can stabilize the absorbing phase against branching. By tuning the level of nonlocality, we observe a transition from the active to the absorbing phase, which belongs to a new universality class.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
6 pages, 3 figures + Supplementary Material (12 pages, 6 figures)
Phonon-mediated spin-polarized superconductivity in altermagnets
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Kristoffer Leraand, Kristian Mæland, Asle Sudbø
We consider the possibility of phonon-mediated unconventional superconductivity in a recently discovered new class of antiferromagnets, dubbed altermagnets. Within a weak-coupling approach, and using a minimal Lieb lattice model for altermagnets, we find a dominant superconducting instability odd in momentum and even in spin with spin-polarized Cooper pairs. We discuss the origin of this unusual result in terms of the spin-structure of the altermagnetic Fermi surface, in combination with the momentum-space structure of the effective phonon-mediated electron-electron interactions on the Fermi surface.
Superconductivity (cond-mat.supr-con)
6+7 pages, 4+1 figures
Dual view of the Z\(_2\)-Gauged XY Model in 3D
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Piers Coleman, Anatoly Kuklov, Alexei Tsvelik
The \(Z_2\) gauged neutral XY model is of long-standing interest both in the context of nematic order, and the study of fractionalization and superconductivity. This paper presents heuristic arguments that no deconfinement of the XY field occurs in this model and presents results of a large-scale Monte Carlo simulations on a cubic lattice which are consistent with this conclusion. The correlation radius determining the confinement is found to be growing rapidly as a function of the parameters in the phase featuring the nematic order. Thus, mesoscopic properties of the system can mimic deconfinement with high accuracy in some part of the phase diagram.
Superconductivity (cond-mat.supr-con), High Energy Physics - Theory (hep-th)
Tuning electrochemical properties and thermal stability of YSZ mesoporous thin films for SOFC applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Bernardo Sievers, Leticia Granja, Andrés Zelcer, Dilson Juan, Valeria Ferrari, Sebastián Passanante, Verónica Lombardo, María Cecilia Fuertes, Rodolfo Oscar Fuentes, Joaquín Sacanell
Dense and mesoporous 4% mol Yttria-stabilized zirconia thin films were deposited on amorphous silica substrates. The effects of the temperature on the mesostructure were analyzed, by applying different thermal treatments to the samples within the range of SOFC operation conditions. Electrochemical impedance spectroscopy measurements rendered evidence of a single mechanism, consistent with grain boundary/surface oxide ion conduction. Our results show that the presence of the highly accessible porosity improves the superficial ionic conductivity, reducing the activation energy of the overall process. Density functional theory calculations on the (110) surface were performed to estimate the associated energy barriers. Our results suggest that ionic transport along the surface of accessible pores connected to the atmosphere could account for the observed reduction in activation energy.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
ACS Appl. Energy Mater. 2025, 8, 2, 894
Designing Flat Bands, Localized and Itinerant States in TaS2 Trilayer Heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Hyeonhu Bae, Roser Valenti, Igor I. Mazin, Binghai Yan
Stacking and twisting van der Waals materials provide a powerful tool to design quantum matter and engineer electron correlation. For instance, monolayers of 1T- and 1H-TaS2 are Mott insulating and metallic (also superconducting), respectively, and thus, the T/H bilayer systems have been extensively investigated in the context of heavy fermions and unconventional superconductivity, which are expected phases from localized spins (1T) coexisting with itinerant electrons (1H). However, recent studies revealed that significant charge transfer from the 1T to 1H layers removes the 1T Mottness and renders the above scenario elusive. In this work, we propose a T/T/H trilayer heterostructure by combining a T/T bilayer -- which is a band insulator with flat dispersion -- with a 1H layer. After charge redistribution, this trilayer heterostructure shows localized spins in the Mott flat band of the T/T bilayer and weak spin polarization in the metallic H layer. We argue that by varying the stacking configurations of the T/T bilayer in the T/T/H trilayer, a crossover from a doped Mott insulator to a Kondo insulator can be achieved. The T/T/H trilayer provides therefore a rich novel heterostructure platform to study strong correlation phenomena and unconventional superconductivity.
Materials Science (cond-mat.mtrl-sci)
A Map of the Zintl AM2Pn2 Compounds: Influence of Chemistry on Stability and Electronic Structure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Andrew Pike, Zhenkun Yuan, Gideon Kassa, Muhammad R Hasan, Smitakshi Goswami, Sita Dugu, Shaham Quadir, Andriy Zakutayev, Sage Bauers, Kirill Kovnir, Jifeng Liu, Geoffroy Hautier
The AM2Pn2 (A= Ca, Sr, Ba, Yb, Mg; M= Mn, Zn, Cd, Mg; and Pn=N, P, As, Sb, Bi) family of Zintl phases has been known as thermoelectric materials and has recently gained much attention for highly promising materials for solar absorbers in single junction and tandem solar cells. In this paper we will, from first-principles, explore the entire family of AM2Pn2 compounds in terms of their ground state structure, thermodynamic stability, and electronic structure. We also perform photoluminescence spectroscopy on bulk powder and thin film samples to verify our results, including the first measurements of the bandgaps of SrCd2P2 and CaCd2P2. The AM2Pn2 compounds exhibit broad stability, are mostly isostructural in the CaAl2Si2-type structure (P3m1), and cover a wide range of bandgaps from 0 to beyond 3 eV. This could make them useful for a variety of purposes, for which we propose several candidates, such as CaZn2N2 for tandem top cell solar absorbers and SrCd2Sb2 and CaZn2Sb2 for infrared detectors. By examining the band structures of the AM2Pn2, we find that Mg3Sb2 has the most promise as a thermoelectric material due to several off-{} valence band pockets which are unique to it among the compositions studied here.
Materials Science (cond-mat.mtrl-sci)
46 pages, 12 figures, submitted to Chemistry of Materials
Effects of altermagnetic order, strain and doping on the optical and vibrational properties of RuO\(_2\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Darshana Wickramaratne, Marc Currie, Shelby S. Fields, Cory D. Cress, Steven P. Bennett
RuO\(_2\), one of the most widely studied transition metal oxides, was recently predicted to host a novel form of collinear magnetic order referred to as altermagnetism. In this study we combine experiment (reflectance, transmittance, ellipsometry and Raman measurements) and first-principles calculations to elucidate the potential role of altermagnetic order, strain and doping on the optical and vibrational properties of RuO\(_2\) grown on TiO\(_2\) (001), (101) and (110) substrates. The combination of experiment and theory in this study surprisingly indicates RuO\(_2\) is in fact best described if one assumes the nonmagnetic state. Calculations of the altermagnetic state leads to poor agreement with the measured optical and vibrational properties of RuO\(_2\).
Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures
Anisotropic Strain Relaxation-Induced Directional Ultrafast Carrier Dynamics in RuO2 Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
S. G. Jeong, I. H. Choi, S. Lee, J. Y. Oh, S. Nair, J. H. Lee, C. Kim, A. Seo, W. S. Choi, T. Low, J. S. Lee, B. Jalan
Ultrafast light-matter interactions inspire potential functionalities in picosecond optoelectronic applications. However, achieving directional carrier dynamics in metals remains challenging due to strong carrier scattering within a multiband environment, typically expected to isotropic carrier relaxation. In this study, we demonstrate epitaxial RuO2/TiO2 (110) heterostructures grown by hybrid molecular beam epitaxy to engineer polarization-selectivity of ultrafast light-matter interactions via anisotropic strain engineering. Combining spectroscopic ellipsometry, X-ray absorption spectroscopy, and optical pump-probe spectroscopy, we revealed the strong anisotropic transient optoelectronic response of strain-engineered RuO2/TiO2 (110) heterostructures along both in-plane [001] and [1-10] crystallographic directions. Theoretical analysis identifies strain-induced modifications in band nesting as the underlying mechanism for enhanced anisotropic carrier relaxation. These findings establish epitaxial strain engineering as a powerful tool for tuning anisotropic optoelectronic responses in metallic systems, paving the way for next-generation polarization-sensitive ultrafast optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
18 pages
Metal-to-superconductor Transition Induced by Lithium Adsorption on Monolayer 1\(T\)-Nb\(_2\)C
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Lingxiao Xiong, Yuhui Yan, Feipeng Zheng
Recently, two-dimensional Nb\(_2\)C has garnered increasing attention due to its functional-group-dependent superconductivity, both experimentally and theoretically. In contrast to the halogen and chalcogen additives that have been the main focus of previous studies, we study the effect of lithium adsorption, which can also be incorporated during the synthesis of Nb\(_2\)C. Our computational analysis reveals a metal-to-superconductor transition in monolayer Nb\(_2\)C with a critical temperature (\(T_{\mathrm{c}}\)) of 22.1 K and a strong anisotropic superconducting gap distribution following the adsorption of lithium atoms. This emergent superconductivity is attributed to the increased electronic states at the Fermi energy, resulting from the contribution of Nb-\(d\) orbitals and electron gas states induced by the low electronegativity of lithium. Furthermore, the application of tensile strain raises the \(T_{\mathrm{c}}\) to 24 K, which is higher than that of most functional-group-modified Nb\(_2\)C systems. Our work deepens the understanding of electron-phonon coupling in layered Nb\(_2\)C, and provides new insights into achieving high critical temperature superconductivity with a strong anisotropic superconducting gap distribution in this system.
Superconductivity (cond-mat.supr-con)
9 pages, 5 figures
Apparent nonreciprocal transport in FeSe bulk crystals
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Taichi Terashima, Shinya Uji, Yuji Matsuda, Takasada Shibauchi, Shigeru Kasahara
We performed low-frequency ac first- and second-harmonic resistance measurements and dc \(I-V\) measurements on bulk FeSe crystals in a temperature range between 1.8 and 150 K and in magnetic field up to 14 T. We observed considerable second-harmonic resistance, indicative of nonreciprocal charge transport, in some samples. By examining correlation between contact resistances and second-harmonic signals, we concluded that the second-harmonic resistance was not due to the genuine nonreciprocal transport effect but was caused by joule heating at a current contact through the thermoelectric effect. Our conclusion is consistent with a recent preprint (Nagata , arXiv:2409.01715), in which the authors reported a zero-field superconducting diode effect in devices fabricated with FeSe flakes and attributed it to the thermoelectric effect.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
9 pages, 12 figures, 1 Table, to appear in Phys. Rev. B
Velocity correlations of vortices and rarefaction pulses in compressible planar quantum fluids
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Ashton S. Bradley, Nils A. Krause
We develop a quantitive analytical treatment of two-point velocity correlations for two important classes of superfluid excitation in compressible quantum fluids: vortices, and rarefaction pulses. We achieve this using two approaches. First, we introduce a new ansatz for describing vortex cores in planar quantum fluids with improved analytic integrability that provides analytic results for power spectra and velocity correlations for general vortex distributions, in good agreement with numerical results using the exact vortex shape. The results show signatures of short and long range correlations associated with vortex dipoles and vortex pairs respectively. Second, for the fast rarefaction pulse regime of the Jones-Roberts soliton the asymptotic high velocity wavefunction provides analytical results for the velocity power spectrum and correlation function, capturing the main length scale of the soliton. We compare our analytical treatment of the homogeneous system with numerical results for a trapped system, finding good quantitative agreement. Our results are relevant to experimental work to characterize quantum vortices and solitons in quantum fluids of atoms and light, and for studies of quantum turbulence.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS), Quantum Physics (quant-ph)
11 pages, 5 figures, comments welcome
Band-edge superfluid of Bose-Einstein condensates in the spin-orbit-coupled Zeeman lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Huaxin He, Fengtao Pang, Hao Lyu, Yongping Zhang
Since the first experimental realization of Bose-Einstein condensates in a spin-orbit-coupled Zeeman lattice, a wide range of applications have been found in these systems. Here, we systematically study the ground-state phase diagram of the systems. We address that the band-edge phase in the ground-state phase diagram is exotic and exists in a very broad parameter regime. The superfluidity of the band-edge states is identified by elementary excitations and superfluid fraction.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
12 pagesm 4 figures
Chiral symmetry breaking and nonreciprocal spin wave in breathing-kagome antiferromagnets at zero field
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
Kazushi Aoyama, Hikaru Kawamura
It has been known that the spin-wave dispersion, which is usually symmetric in the momentum space with respect to \({\bf q}=0\), can be asymmetric in the presence of the Dzaloshinskii-Moriya (DM) interaction and an applied magnetic field. Here, we theoretically demonstrate that in \(J_3\)-dominant classical Heisenberg antiferromagnets on the breathing kagome lattice, the asymmetric spin-wave dispersion appears in a chiral phase due to non-uniform geometric phases acquired in the spin-wave propagation processes. This points to the emergence of a nonreciprocal spin wave in the absence of both the DM interaction and the magnetic field. Reflecting the asymmetry, positive-spin-chirality and negative-spin-chirality states, either one of which is selected in the low-temperature phase by the symmetry breaking, show different spin-wave dispersions, suggesting that the two energetically-degenerate chiral states can be distinguished by the spin-wave propagation.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 5 figures, 3 tables
The effect of duty cycle on electron transmission through a graphene electrostatic barrier
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
R. Biswas, S. Mukhopadhyay, C. Sinha
We investigated theoretically the transmission properties of Dirac Fermions tunneling through a periodically (sinusoidal and rectangular) driven electrostatic barrier in Monolayer graphene. For the time harmonic potential with moderate to high alpha (=amplitude/frequency) the central Floquet band is found to be almost cloaked for the Klein transmitted electron in contrast to electron at higher grazing incidences. As a time periodic drive, we mainly focused on the use of rectangular wave electric signal to modulate the transparency of the barrier. It is noted that the asymmetric Fano resonance, a characteristic feature of photon assisted tunneling, is more likely to occur for rectangular drive in contrast to the harmonic one. The height of the modulating potential is particularly responsible for the dressing effect of the barrier. The position and nature of the FR can be tailored by changing the height and frequency of the rectangular drive. Moreover, the duty cycle of the driving potential turns out to be an important controlling parameter for the transmission process. Thus, the rectangular modulation plays an important role for the occurrence and detection of the Fano resonances which is vital for the use of graphene nanostructure in the field of detectors, sensors, modulators etc. The present findings attempt for the first time, to realize the effect of duty cycle on the quantum interference in semiconductor nanostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 pages with 5 figures
Dynamics of the Bose-Hubbard Model Induced by On-Site or Long-Range Two-Body Losses
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Julien Despres, Leonardo Mazza, Marco Schirò
We present a theoretical study of the dissipative dynamics of the Bose-Hubbard model induced by on-site or long-range two-body losses. We first consider the one-dimensional chain and the two-dimensional square lattice, and study the dynamics induced by the sudden switch-on of two-body losses on a weakly-interacting superfluid state. The time-dependent density is obtained in the spirit of the Bogolyubov approach by calculating theoretically the equations of motion associated to the relevant quadratic bosonic correlators. In the one-dimensional case, our results compare very well with quasi-exact numerical calculations based on the quantum jump method implemented using tensor networks. We find that the intermediate-time dynamics of the density displays an algebraic decay characterized by an interaction-dependent power-law exponent. The latter property still holds for long-range two-body loss processes but it is absent in the two-dimensional square lattice with on-site losses. We finally investigate the dissipative quench dynamics starting from a strongly-correlated superfluid state or from a Mott-insulating state; for the Bose-Hubbard chain initially confined in the superfluid-correlated regime, an unexpected strong decay of the density appearing at short times is revealed.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
20 pages, 16 figures
Recent Progress in Studies of Cobalt-based Quasi-1-dimensional Quantum Magnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
The interplay of crystal electric field, temperature, and spin-orbit coupling can yield a Kramers ion and thus an effective S = 1/2 ground state for Co2+ ions (3d7), which is often the case for low dimensional materials. This is because a highly anisotropic structural motif can force the spins to point either up or down, hence becoming a system where spins communicate via Ising interactions. Cobalt-based quasi-1-dimensional materials have been studied in this context since the latter half of the 20th century, but due to the development of modern characterization techniques and advances in sample preparation, the exotic physical phenomena that have generated the most interest have only emerged in the most recent three to four decades. This topical review mainly summarizes progress in cobalt-based quasi-1-dimensional quantum magnets, and comments on a few research directions of potential future interest.
Materials Science (cond-mat.mtrl-sci)
32 pages, 11 figures, accepted for publication in the Frontiers of Physics
Exploration of Zeolites as High-Performance Electrode Protective Layers for Alkali-Metal Batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
The electrode-electrolyte interfaces play pivotal roles in alkali-metal batteries, necessitating superior electrochemical stability, excellent electrical insulation, and high ionic conductivity. This study proposes using zeolites as interfacial protective layers owing to their inherently high stability with both alkali metals and high-voltage cathodes, as well as exceptionally wide bandgaps that minimize electron transport. To further pinpoint zeolites with rapid ionic diffusivity among their versatile structures, we devise a universal approach to explore diffusion dynamics in arbitrary structures. Through first-principles calculations, we identify the diffusion networks of Li+, Na+, and K+ in twenty-two, seventeen, and four zeolites, respectively. Eventually, we predict five, seven, and three zeolites as suitable interfacial protective layer for lithium-, sodium-, and potassium-metal batteries, respectively, each characterized by a diffusion barrier below 0.3 eV. This research automates the exploration of diffusion dynamics in complex materials and underscores the significant potential of zeolites as interfacial protective layers in alkali-metal batteries.
Materials Science (cond-mat.mtrl-sci)
Soliton resuscitations: asymmetric revivals of the breathing mode of an atomic bright soliton in a harmonic trap
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Waranon Sroyngoen, James R. Anglin
We study the collective modes of an atomic bright soliton realised in a quasi-one-dimensional Bose-Einstein condensate, using Bogoliubov-de Gennes theory. In particular we focus on the breathing mode of the soliton, which is not a single linearized normal mode but a common component of many modes, and therefore decays within a \(t^{-1/2}\) envelope due to dispersion. If the soliton is held in the center of a harmonic trap, we show that the breathing amplitude revives periodically, as atoms shed from the vibrating soliton oscillate in the trap, and return. After each revival the breathing amplitude again decays, and this cycle repeats every trap half-period. The amplitude envelope of these breathing revivals shows a curious asymmetry, however, with a gradual increase in breathing followed by sudden drop in breathing amplitude that becomes more and more pronounced in later revivals. We explain this asymmetrical revival pattern by deriving a close analytical approximation to the Bogoliubov-de Gennes frequency spectrum, and offer this coherent Bogoliubov-de Gennes phenomenon as a background against which to compare possible quantum many-body effects, including decoherence over trap-period time scales.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
13 pages, 4 figures
Eliminating nanometer-scale asperities on metallic thin films through plasma modification processes studied by molecular dynamics and AFM
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Tomoyuki Tsuyama, Tatsuki Oyama, Yu Azuma, Haruhisa Ohashi, Masahiro Irie, Ayumi Yamakawa, Shoko Uetake, Takayuki Konno, Takahiro Ukai, Kohei Ochiai, Nobuyuki Iwaoka, Atsushi Hashimoto, Yoshishige Okuno
We report the effects of reducing surface asperity size at the nanometer scale on metallic surfaces by plasma-assisted surface modification processes using simulations and experiments. Molecular dynamics (MD) simulations were conducted by irradiating various inert gas ions (Ne, Ar, Kr, and Xe) onto a cobalt slab with nanoscale asperities on the surface. The MD simulations showed that as the atomic number of the inert gas increased the surface asperity size was reduced more efficiently, while the etching rate decreased. The dependencies of the scattering behaviors on the inert gas ions originated from the mass exchange between the working gas ions and the slab atoms. Atomic force microscopy and x-ray fluorescence measurements were performed on hard disk media subjected to the surface modification processes. These measurements experimentally demonstrated that the density of nanoscale asperities was reduced with a lower etching rate as the atomic number of the inert gas increased, consistent with the simulation results. Through this study, we clarified that heavier working gases were more effective in reducing surface asperity size without significantly reducing the thickness of the material, which can contribute to better control of surface morphologies at the nanometer scale.
Materials Science (cond-mat.mtrl-sci)
11 pages, 7 figures, 1 table
Quantify the stability of Majorana qubits through Rabi beat
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
Yu Zhang, Jiayi Chen, Jie Liu, X.C. Xie
Evaluating the stability of Majorana qubits (MQ) is crucial for the advancement of topological quantum computation. In this work, we propose a method to quantify the stability of MQs through their Rabi this http URL approach involves coupling a fermionic state to the MQ and measuring the resulting Rabi oscillations induced by this coupling. This setup is feasible across a range of experimental this http URL show that Rabi beats emerge when considering finite-size effects and inhomogeneous potentials. The beating frequency is directly related to the deviations caused by these factors, providing a quantitative method to assess the stability of Majorana this http URL, we investigate the impact of dissipation on MQ stability. We find that the beating patterns are unaffected by weak dissipation. More intriguingly, dissipation would weaken in an ideal MQ. This suggests that non-local qubits can effectively avoid certain types of decoherence.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 4 figures
Critical Motility-Induced Phase Separation in Three Dimensions is Consistent with Ising Universality
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Numerical investigations aiming to determine the universality class of critical motility-induced phase separation (MIPS) in two dimensions (2D) have resulted in inconclusive findings. Here, using finite-size scaling results obtained from large-scale computer simulations, we find that the static and dynamic critical exponents associated with 3D MIPS all closely match those of the 3D Ising universality class with a conserved scalar order parameter. This finding is corroborated by fluctuating hydrodynamic description of the critical dynamics of the order parameter field which precisely matching model B in three dimensions. Our work suggests that 3D MIPS and indeed the entire phase diagram of active Brownian spheres is remarkably similar to that of molecular passive fluids despite the absence of Boltzmann statistics.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Basic mechanisms for understanding container-content interactions: a fundamental perspective and application to polymer materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Emmanuelle Feschet-Chassot, Philip Chennell
This article provides a comprehensive understanding of the interactions that can occur at the interface between liquids and materials. It describes the phenomena of sorption (adsorption and absorption), permeation and leaching from a physicochemical perspective. In addition to examining these interactions, the historical context, detailing how these phenomena have been studied and demonstrated over time, it provides an understanding of the evolution of research in this field and the methodologies used to study these interactions, with a specific focus on polymer materials. The mechanisms underlying these interactions are presented as well as the equations that describe the processes involved, thus providing a scientific basis for understanding the complexities of container-content interactions.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
47 pages, 12 figures
Interfacial Polarization Switching in Al0.92Sc0.08N/GaN Heterostructures Grown by Sputter Epitaxy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Niklas Wolff, Georg Schönweger, Redwanul Md. Islam, Ziming Ding, Christian Kübel, Simon Fichtner, Lorenz Kienle
The integration of ferroelectric nitride thin films such as Al1-xScxN onto GaN templates could enable enhanced functionality in novel high-power transistors and memory devices. This requires a detailed understanding of the ferroelectric domain structures and their impact on the electric properties. In this contribution, the sputter epitaxy of highly coherent Al0.92Sc0.08N thin films grown on GaN approaching lattice-matching conditions is demonstrated. Scanning transmission electron microscopy investigations reveal the formation of polar domains and the mechanism of domain propagation upon ferroelectric switching. Atomic resolution imaging suggests that polarization inversion is initiated by an interfacial switching process in which already the first atomic layer of Al1-xScxN changes its polarization from the as-grown M- to N-polarity. An atomically sharp planar polarization discontinuity is identified at the Al0.92Sc0.08N/GaN interface and described by atomic modeling and chemical structure analysis using electron energy loss spectroscopy, considering local lattice spacings. Moreover, residual domains with M-polarity are identified at the top Pt electrode interface. These insights on the location and the atomic structure of ferroelectric inversion domains in sputter deposited Al1-xScxN/GaN heterostructures will support the development of future non-volatile memory devices and novel HEMT structures based on ferroelectric nitride thin films via interface engineering.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
14 pages, 7 figures
Universal criterion for selective outcomes under stochastic resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Suvam Pal, Leonardo Dagdug, Dibakar Ghosh, Denis Boyer, Arnab Pal
Resetting plays a pivotal role in optimizing the completion time of complex first passage processes with single or multiple outcomes/exit possibilities. While it is well established that the coefficient of variation -- a statistical dispersion defined as a ratio of the fluctuations over the mean of the first passage time -- must be larger than unity for resetting to be beneficial for any outcome averaged over all the possibilities, the same can not be said while conditioned on a particular outcome. The purpose of this letter is to derive a universal condition which reveals that two statistical metric -- the mean and coefficient of variation of the conditional times -- come together to determine when resetting can expedite the completion of a selective outcome, and furthermore can govern the biasing between preferential and non-preferential outcomes. The universality of this result is demonstrated for a one dimensional diffusion process subjected to resetting with two absorbing boundaries.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Probability (math.PR), Chemical Physics (physics.chem-ph)
13 pages, 4 figures
Quantum geometry and the electric magnetochiral anisotropy in noncentrosymmetric polar media
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
Pierpaolo Fontana, Victor Velasco, Chang Niu, Peide D. Ye, Pedro V. Lopes, Kaio E. M. de Souza, Marcus V. O. Moutinho, Caio Lewenkopf, Marcello B. Silva Neto
The electric magnetochiral anisotropy is a nonreciprocal phenomenon accessible via second harmonic transport in noncentrosymmetric, time-reversal invariant materials, in which the rectification of current, \({\bf I}\), can be controlled by an external magnetic field, \({\bf B}\). Quantum geometry, which characterizes the topology of Bloch electrons in a Hilbert space, provides a powerful description of the nonlinear dynamics in topological materials. Here, we demonstrate that the electric magnetochiral anisotropy in noncentrosymmetric polar media owes its existence to the quantum metric, arising from the spin-orbit coupling, and to large Born effective charges. In this context, the reciprocal magnetoresistance \(\beta{\bf B}^2\) is modified to \(R( I,P,B)=R_0[1+\beta B^2 + \gamma^{\pm}{\bf I}\cdot({\bf P}\times{\bf B})]\), where the chirality dependent \(\gamma^{\pm}\) is determined by the quantum metric dipole and the polarization \({\bf P}\). We predict a universal scaling \(\gamma^{\pm}(V)\sim V^{-5/2}\) which we verified by phase sensitive, second harmonic transport measurements on hydrothermally grown 2D tellurium films under applied gate voltage, \(V\). The control of rectification by varying \({\bf I}\), \({\bf P}\), \({\bf B}\), and \(V\), demonstrated in this work, opens up new avenues for the building of ultra-scaled CMOS circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures + 10 pages, 4 figures of Supplemental Material
Sliding dynamics of a particle in a soap film
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Youna Louyer, Benjamin Dollet, Isabelle Cantat, Anaïs Gauthier
We investigate the sliding dynamics of a millimeter-sized particle trapped in a horizontal soap film. Once released, the particle moves toward the center of the film in damped oscillations. We study experimentally and model the forces acting on the particle, and evidence the key role of the mass of the film on its shape and particle dynamics. Not only is the gravitational distortion of the film measurable, it completely determines the force responsible for the motion of the particle - the catenoid-like deformation induced by the particle has negligible effect on the dynamics. Surprisingly, this is expected for all film sizes as long as the particle radius remains much smaller than the film width. We also measure the friction force, and show that ambient air and the film contribute almost equally to the friction. The theoretical model that we propose predicts exactly the friction coefficient as long as inertial effects can be neglected in air (for the smallest and slowest particles). The fit between theory and experiments sets an upper boundary of 0.01 {}Pa s m for the surface viscosity, in excellent agreement with recent interfacial microrheology measurements.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
13 pages, 5 figures
Fundamental Theory of Current-Induced Motion of Magnetic Skyrmions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
Magnetic skyrmions are topological spin textures that appear in magnets with broken spatial inversion symmetry via competition between the (anti)ferromagnetic exchange interactions and the Dzyaloshinskii-Moriya interactions in a magnetic field. Their current-driven dynamics have been extensively studied aiming at spintronic applications. However, current-induced skyrmion motion exhibits diverse behaviors depending on various factors and conditions such as the type of skyrmion, driving mechanism, system geometry, direction of applied current, and type of the magnet. While this variety attracts enormous research interest of fundamental science and enriches their possibilities of technical applications, it is, at the same time, a source of difficulty and complexity that hinders their comprehensive understandings. In this article, we discuss fundamental and systematic theoretical descriptions of current-induced motion of skyrmions driven by the spin-transfer torque and the spin-orbit torque. Specifically, we theoretically describe the behaviors of current-driven skyrmions depending on the factors and conditions mentioned above by means of analyses using the Thiele equation. Furthermore, the results of the analytical theory are visually demonstrated and quantitatively confirmed by micromagnetic simulations. In particular, we discuss dependence of the direction and velocity of motion on the type of skyrmion (Bloch type and Neel type) and its helicity, the system geometry (thin plate and nanotrack), the direction of applied current (length and width direction of the nanotrack) and its spin-polarization orientation, and the type of magnet (ferromagnet and antiferromagnet). The comprehensive theory provided by this article is expected to contribute significantly to research on the manipulation and control of magnetic skyrmions by electric currents for future spintronics applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
34 pages, 11 figures, published in Journal of Physics: Condensed Matter as a Topical Review
J. Phys.: Condens. Matter 37 023003/1-34 (2025)
Orbital-selective correlation effects and superconducting pairing symmetry in a multiorbital \(t\)-\(J\) model for bilayer nickelates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Guijing Duan, Zhiguang Liao, Lei Chen, Yiming Wang, Rong Yu, Qimiao Si
The recent discovery of superconductivity in La\(_3\)Ni\(_2\)O\(_7\) raises key questions about its mechanism and the nature of pairing symmetry. This system is believed to be described by a bilayer two-orbital Hubbard model. The considerations of orbital-selective Mott correlations motivate a bilayer two-orbital \(t\)-\(J\) model and, accordingly, we study the superconducting pairing in this model. We obtain an overall phase diagram of superconductivity, where the leading channel has either extended \(s\)-wave or \(d_{x^2-y^2}\)-wave symmetry. Our analysis highlights how the orbital-selective correlations affect the superconducting pairing via the interlayer exchange couplings and low-energy electronic structure. In particular, we find that the dominant orbital for the pairing may change between \(z^2\) and \(x^2-y^2\) when the position of the bonding \(z^2\) band is varied by tuning either the \(c\)-axis lattice constant or electron concentration strength. We discuss the implications of these results for the superconductivity in both bulk La\(_{3}\)Ni\(_{2}\)O\(_{7}\) and its thin film counterpart.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
6+2 pages, 4+2 figures
Water-in-water PEG/DEX/protein microgel emulsions: effect of microgel particle size on the rate of emulsion phase separation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Andrzej Balis, Georgi Gochev, Domenico Truzzolillo, Dawid Lupa, Liliana Szyk-Warszynska, Jan Zawala
Protein nanoparticles have been proven to be highly effective stabilizers of water-in-water emulsions obtained from a number of different types of aqueous two-phase systems (ATPS). The stabilizing efficiency of such particles is attributed to their affinity to the water/water interface of relevant ATPS, and emulsion formulations with long-term stability were reported in the recent years. In this study we investigated the macroscopic dynamics of the early-stage time evolution of dextran-in-polyethylene glycol emulsions obtained from a single ATPS and containing beta-lactoglobulin microgel particles of various diameters (ca. 40-190 nm). The results revealed the existence of a threshold in microgel size above which the water-in-water emulsion is stabilized, and that the process of segregative phase separation is determined by the interplay of droplets coalescence and sedimentation. Efficient droplet coalescence inhibition was found for microgel particles larger than 60 nm. Based on previous literature results, we discuss our coalescence-driven phase separation data in the context of the formation of durable particle layers on the emulsion droplets and the resulting droplet-droplet interactions.
Soft Condensed Matter (cond-mat.soft)
31 Pages, 10 figures + Supplementary Materials
Modeling and Physics of Multiferroic Perovskite Manganites
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
A new type of multiferroicity was experimentally discovered in 2003 in a perovskite manganite TbMnO\(_3\) where its ferroelectricity is induced by cycloidally ordered Mn spins. Susequently, such spin-cycloid multiferroic phase was also discovered in \(R\)MnO\(_3\) with other rare-earth ions \(R\)=Dy, Eu\(_{1-x}\)Y\(_x\), Tb\(_{1-x}\)Gd\(_x\), etc. In this class of materials, the magnetism and ferroelectricity are inseparably coupled, and resulting strong magnetoelectric coupling enables us to control/manipulate the electricity (magnetism) by magnetic (electric) fields. Moreover, many interesting magnetoelectric phenomena due to their cross correlation have been discovered. In this article, we discuss a microscopic theoretical model for \(R\)MnO\(_3\) constructed by taking into account their precise electronic and lattice structures and overview the theoretical works based on this model which elucidated rich magnetoelectric phenomena of \(R\)MnO\(_3\). The perovskite manganites are not only the first-discovered spin-spiral multiferroic materials but also a typical class of materials that exhibits most of the magnetoelectric phenomena manifested in many other multiferroics. Therefore, the comprehensive understanding of \(R\)MnO\(_3\) directly leads to the clarification of universal physics of magnetoelectric phenomena in multiferroic materials.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
16 pages, 19 figures, published in Journal of the Physical Society of Japan as Special Topics for 70 Years of Tanabe-Sugano Diagrams
J. Phys. Soc. Jpn. 93, 121004/1-16 (2024)
Machine-Learning Detection of the Berezinskii-Kosterlitz-Thouless Transitions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Masahito Mochizuki, Yusuke Miyajima
The Berezinskii-Kosterlitz-Thouless (BKT) transition is a typical topological phase transition defined between binding and unbinding states of vortices and antivortices, which is not accompanied by spontaneous symmetry breaking. It is known that the BKT transition is difficult to detect from thermodynamic quantities such as specific heat and magnetic susceptibility because of the absence of anomaly in free energy and significant finite-size effects. Therefore, methods based on statistical mechanics which are commonly used to discuss phase transitions cannot be easily applied to the BKT transition. In recent years, several attempts to detect the BKT transition using machine-learning methods based on image recognition techniques have been reported. However, it has turned out that the detection is difficult even for machine learning methods because of the absence of trivial order parameters and symmetry breaking. Most of the methods proposed so far require prior knowledge about the models and/or preprocessing of input data for feature engineering, which is problematic in terms of the general applicability. In this article, we introduce recent development of the machine-learning methods to detect the BKT transitions in several spin models. Specifically, we demonstrate the success of two new methods named temperature-identification method and phase-classification method for detecting the BKT transitions in the q-state clock model and the XXZ model. This progress is expected to sublimate the machine-learning-based study of spin models for exploring new physics beyond simple benchmark test.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 12 figures, published in Journal of the Physical Society of Japan as Special Topics for machine learning physics
J. Phys. Soc. Jpn. 94, 031003/1-13 (2024)
Modelling spin-orbitronics effects at interfaces and chiral molecules
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Poonam Kumari, Cyrille Barreteau, Alexander Smogunov
Using orbital angular momentum (OAM) currents in nanoelectronics, for example, for magnetization manipulation via spin-orbit torque (SOT), represents a growing field known as "spin-orbitronics". Here, using the density functional theory (DFT) and the real-time dynamics of electronic wave packets, we explore a possibility of generation and propagation of orbital currents in two representative systems: an oxidized Cu surface (where large OAMs are known to form at the Cu/O interface) and a model molecular junction made of two carbon chains connected by a chiral molecule. In the Cu/O system, the orbital polarization of an incident wave packet from the Cu lead is strongly enhanced at the Cu/O interface but then rapidly decays in the bulk Cu due to orbital quenching of asymptotic bulk states. Interestingly, if a finite transmission across the oxygen layer is allowed (in a tunnel junction geometry, for example), a significant spin-polarization of transmitted (or reflected) currents is instead predicted which persists at a much longer distance and can be further tuned by an applied in-plane voltage. For the molecular junction, the mixing of the carbon \(p_x\) and \(p_y\) (degenerate) channels by the chiral molecular orbital gives rise not only to an efficient generation of orbital current but also to its long-range propagation along the carbon chain.
Materials Science (cond-mat.mtrl-sci)
Approaching the ultrastrong coupling regime between an Andreev level and a microwave resonator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
O.O. Shvetsov, A. Khola, V. Buccheri, I.P.C. Cools, N. Trnjanin, T. Kanne, J. Nygård, A. Geresdi
Josephson junctions formed in semiconductor nanowires host Andreev bound states and serve as a physical platform to realize Andreev qubits tuned by electrostatic gating. With the Andreev bound state being confined to the nanoscale weak link, it couples to a circuit-QED architecture via the state-dependent supercurrent flowing through the weak link. Thus, increasing this coupling strength is a crucial challenge for this architecture. Here, we demonstrate the fabrication and microwave characterization of an InAs nanowire weak link embedded in a superconducting loop with a lumped-element resonator patterned from a thin NbTiN film with high kinetic inductance. We investigated several devices with various weak link lengths and performed spectroscopy of spin-degenerate and spin-orbit split Andreev bound states for the shorter and longer weak links, respectively. Our approach offers a compact geometry and a large resonator impedance above 12 k\(\Omega\) at a resonator frequency of 8 GHz, which results in a measured coupling strength reaching 1.95 GHz to the Andreev level and 77 MHz to the Andreev spin. Our spectroscopic data are in good agreement with existing theoretical models and demonstrate ultrastrong coupling to the Andreev pair qubit with the coupling strength approaching the bare resonator and qubit frequencies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
The quest for new materials: the network theory and machine learning perspectives
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Jacopo Moi, Davide Spallarossa, Stefano Bonetti, Raffaella Burioni, Guido Caldarelli
Understanding and predicting the emergence of novel materials is a fundamental challenge in condensed matter physics, materials science and technology. With the rapid growth of materials databases in both size and reliability, the challenge shifts from data collection to efficient exploration of this vast and complex space. A key strategy lies in a smart use of descriptors at multiple scales, ranging from atomic arrangements to macroscopic properties, to represent materials in high-dimensional abstract spaces. Network theory provides a powerful framework to structure and analyze these relationships, capturing hidden patterns and guiding discovery. Machine Learning complements this approach by enabling predictive modeling, dimensionality reduction, and the identification of promising material candidates. By integrating network-based methods with Machine Learning techniques, researchers can construct, analyze, and efficiently navigate the material space, uncovering novel materials with tailored properties. This review explores the synergy between network theory and ML, highlighting their role in accelerating materials discovery through a systematic and interpretable approach.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Other Condensed Matter (cond-mat.other), Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
12 pages, 5 figures
Collective magnetism of atomic momentum states
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Garrett R. Williams, Rishi P. Lohar, Tao Chen, Brian L. DeMarco, Bryce Gadway
Organization and ordering from interactions in many-body systems underlies our understanding of phases of classical and quantum matter. Magnetism has played a particularly foundational role in the study of many-body phases. Here, we explore the collective magnetism that emerges from two laser-coupled momentum modes of a scalar bosonic quantum gas. We employ adiabatic state preparation and explore the collective magnetization response to an applied bias potential, finding that the relative increase of interactions leads to an enhanced and muted response for the ground state and excited state, respectively. We further find evidence for significant \(Z_2\) symmetry breaking of the sample magnetization for the ground state, consistent with the expected beyond-mean-field behavior. These results suggest that the nonlinear interactions of scalar Bose condensates could provide a simple, direct path towards the squeezing of momentum states for quantum sensing.
Quantum Gases (cond-mat.quant-gas)
6 pages, 4 figures ; Supplementary Materials document included as ancillary file
Chirality-induced Spin-Orbit Coupling and Spin Selectivity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
Massimiliano Di Ventra, Rafael Gutierrez, Gianaurelio Cuniberti
We show that a spinor traveling along a helical path develops a spin-orbit coupling due to the cur- vature of the path. We then estimate the magnitude of this eff ective geometric spin-orbit interaction for structures that showcase chiral-induced spin selectivity (CISS). We fi nd that this chiral-induced spin-orbit coupling (-SOC), coupled to broken time-reversal symmetry, may provide a simple, yet rigorous way to describe the CISS phenomenon.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Phase space contraction rate for classical mixed states
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Mohamed Sahbani, Swetamber Das, Jason R. Green
Physical systems with non-reciprocal or dissipative forces evolve according to a generalization of Liouville's equation that accounts for the expansion and contraction of phase space volume. Here, we connect geometric descriptions of these non-Hamiltonian dynamics to a recently established classical density matrix theory. In this theory, the evolution of a "maximally mixed" classical density matrix is related to the well-known phase space contraction rate that, when ensemble averaged, is the rate of entropy exchange with the surroundings. Here, we extend the definition of mixed states to include statistical and mechanical components, describing both the deformations of local phase space regions and the evolution of ensembles within them. As a result, the equation of motion for this mixed state represents the rate of contraction for an ensemble of dissipative trajectories. Recognizing this density matrix as a covariance matrix, its contraction rate is another measure of entropy flow characterizing nonequilibrium steady states.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Chaotic Dynamics (nlin.CD)
Classical density matrix theory, Jacobi formula, Liouville's equation; comments are welcome
Evidence of the matrix effect on a compositionally graded oxide thin film
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
J. Scola, F. Jomard, E. Loire, J. Wolfman, B. Negulescu, G. Z. Liu, M.-A. Pinault-Thaury
A heterostructure of Ba\(_{1-x}\)Sr\(_x\)TiO\(_3\)/La\(_{1.1}\)Sr\(_{0.9}\)NiO\(_3\) /SrTiO\(_3\) has been analysed by magnetic sector secondary ion mass spectrometry (SIMS). The stoichiometry parameter \(x\) of the top layer was made varying continuously from 0 to 1 along the width of the sample by combinatorial pulsed laser deposition. Prior to SIMS analysis, the composition gradient of Ba\(_{1-x}\)Sr\(_x\)TiO\(_3\) was quantitatively characterized by chemical characterizations including wavelength and energy dispersive X-ray spectroscopies. Even if the Ti content is constant into Ba\(_{1-x}\)Sr\(_x\)TiO\(_3\){}, its ionic yield exhibits an increasing trend as Ba is substituted by Sr. Such a phenomenon can be explained by the variation of the neighbouring atoms chemistry which affects the ionization probability of titanium during the sputtering process. In addition to the continuously varying composition, the oxide multilayer sample features sharp interfaces hence the in-depth resolution under our analysing conditions has been investigated too. The modelling of the interface crossing profiles reveals that the instrumental contribution to the profile broadening is as low as 5 nm.
Materials Science (cond-mat.mtrl-sci)
Controlling Symmetries and Quantum Criticality in the Anisotropic Coupled-Top Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
Wen-Jian Mao, Tian Ye, Liwei Duan, Yan-Zhi Wang
We investigate the anisotropic coupled-top model, which describes the interactions between two large spins along both \(x-\) and \(y-\)directions. By tuning anisotropic coupling strengths along distinct directions, we can manipulate the system's symmetry, inducing either discrete \(Z_2\) or continuous U(1) symmetry. In the thermodynamic limit, the mean-field phase diagram is divided into five phases: the disordered paramagnetic phase, the ordered ferromagnetic or antiferromagnetic phases with symmetry breaking along either \(x-\) or \(y-\)direction. This results in a double degeneracy of the spin projections along the principal direction for \(Z_2\) symmetry breaking. When U(1) symmetry is broken, infinite degeneracy associated with the Goldstone mode emerges. Beyond the mean-field ansatz, at the critical points, the energy gap closes, and both quantum fluctuations and entanglement entropy diverge, signaling the onset of second-order quantum phase transitions. These critical behaviors consistently support the universality class of \(Z_2\) symmetry. Contrarily, when U(1) symmetry is broken, the energy gap vanishes beyond the critical points, yielding a novel exponent of 1, rather than 1/2 for \(Z_2\) symmetry breaking. The framework provides an ideal platform for experimentally controlling symmetries and investigating associated physical phenomena.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
21 pages, 3 figures
Angle-dependent dissipation effects in topological insulator-based Josephson junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Ardamon Sten, Paramita Dutta, Sudeep Kumar Ghosh
Dissipation fundamentally alters quantum transport in Josephson
junctions. Here, we demonstrate unique transport signatures in
dissipative topological insulator-based Josephson junctions, which
provide a powerful platform for exploring the competition between
dissipation and topological protection. We incorporate dissipation
effects by coupling a
lossy' metallic lead at the junction to an electron reservoir, and describe its effects using an effective non-Hermitian Hamiltonian within the Lindblad formalism. Non-Hermiticity introduces finite lifetimes to the helical Andreev bound states in the junction, with imaginary energy components that depend on the quasiparticle incidence angle, while Klein tunneling remains robust for normal incidence. Unlikeordinary'
non-Hermitian Josephson junctions, this system exhibits no Josephson
gaps or forbidden regions, preserving topological protection. In the
fully non-Hermitian regime, a tunable line of zero-energy states
emerges, bounded by exceptional-like points with divergent
supercurrents. Our results reveal how dissipation reshapes
superconducting transport in topological insulator-based Josephson
junctions, opening new directions for dissipation-engineered hybrid
quantum devices.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
8 pages, 5 figures. Comments are welcome
Dialectics of antimicrobial peptides I: common mechanisms of offensive and protecting roles of the peptides
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Marta V. Volovik, Zaret G. Denieva, Oleg V. Kondrashov, Sergey A. Akimov, Oleg V. Batishchev
Antimicrobial peptides (AMPs) have intrigued researchers for decades due to the contradiction between their high potential against resistant bacteria and the inability to find a structure-function relationship for the development of an effective and non-toxic agent. In the present study and the companion paper [Phys. Rev. E (2024)], we performed a comprehensive experimental and theoretical analysis of various aspects of AMP-membrane interactions and AMP-induced pore formation. Using the well-known melittin and magainin as examples, we showed, using patch-clamp and fluorescence measurements, that these peptides, even at nanomolar concentrations, modify the membrane by making it permeable to protons (and, possibly, water), but not to ions, and protect the membrane from large pore formation after subsequent addition of 20-fold higher concentrations of AMPs. This protective effect is independent of the membrane side (or both sides) of the peptide addition and is determined by the peptide-induced deformations of the membrane. Peptides create small, H+-permeable pores that incessantly connect the opposing membrane leaflets, allowing translocation of peptides and lipids and thus preventing further generation of large lateral pressure/tension imbalance. At the same time, such an imbalance is a key to the formation of peptide-induced pores at high AMP concentrations, with the main contribution coming from single ion-conducting events rather than stable channel-like structures. Therefore, our results suggest that lowering the AMP concentration, which is a common principle to reduce toxicity, may actually make bacteria resistant to AMP. However, a protective pre-treatment with nanomolar concentrations of peptides may be the key to protect eukaryotic cells from the high concentrations of AMPs.
Soft Condensed Matter (cond-mat.soft)
Superconducting diode efficiency from singlet-triplet mixing in disordered systems
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-14 20:00 EST
Jaglul Hasan, Daniel Shaffer, Maxim Khodas, Alex Levchenko
The superconducting diode effect (SDE) -- the nonreciprocity of the critical current in a bulk superconductor -- has garnered significant attention due to its potential applications in superconducting electronics. However, the role of disorder scattering in SDE has rarely been considered, despite its potential qualitative impact, as we demonstrate in this work. We investigate SDE in a disordered Rashba superconductor under an in-plane magnetic field, employing a self-consistent Born approximation to derive the corresponding Ginzburg-Landau theory. Our analysis reveals two surprising effects. First, in the weak Rashba spin-orbit coupling (SOC) regime, disorder can reverse the direction of the diode effect, indicated by a sign change in the superconducting diode efficiency coefficient. Second, in the strong Rashba SOC regime, disorder becomes the driving mechanism of SDE, which vanishes in its absence. In this case, we show that disorder-induced mixing of singlet and triplet superconducting orders underlies the effect.
Superconductivity (cond-mat.supr-con)
9 figures, 14 pages
Transformer-Enhanced Variational Autoencoder for Crystal Structure Prediction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Ziyi Chen, Yang Yuan, Siming Zheng, Jialong Guo, Sihan Liang, Yangang Wang, Zongguo Wang
Crystal structure forms the foundation for understanding the physical and chemical properties of materials. Generative models have emerged as a new paradigm in crystal structure prediction(CSP), however, accurately capturing key characteristics of crystal structures, such as periodicity and symmetry, remains a significant challenge. In this paper, we propose a Transformer-Enhanced Variational Autoencoder for Crystal Structure Prediction (TransVAE-CSP), who learns the characteristic distribution space of stable materials, enabling both the reconstruction and generation of crystal structures. TransVAE-CSP integrates adaptive distance expansion with irreducible representation to effectively capture the periodicity and symmetry of crystal structures, and the encoder is a transformer network based on an equivariant dot product attention mechanism. Experimental results on the carbon_24, perov_5, and mp_20 datasets demonstrate that TransVAE-CSP outperforms existing methods in structure reconstruction and generation tasks under various modeling metrics, offering a powerful tool for crystal structure design and optimization.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
Dialectics of antimicrobial peptides II: Theoretical models of pore formation and membrane protection
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Oleg V. Kondrashov, Marta V. Volovik, Zaret G. Denieva, Polina K. Gifer, Timur R. Galimzyanov, Peter I. Kuzmin, Oleg V. Batishchev, Sergey A. Akimov
Amphipathic peptides are considered promising antibiotics because of their ability to form pores in bacterial membranes. In two companion papers, we analyzed both experimentally and theoretically the mechanisms and consequences of the interaction of two types of amphipathic peptides (magainin and melittin) with lipid membranes. We studied this interaction for different peptide concentration: low, high, and low concentration followed by the addition of peptides in high concentration. Here we provide the theoretical description of the pore formation mechanisms. We predicted theoretically that two peptide molecules are enough to locally induce the formation of a small metastable pore that continuously connects two membrane leaflets and allows peptide and lipid translocation between the leaflets. This mechanism (referred to as local) is supposed to work at low peptide concentrations. When applied in high concentration, the one-sided adsorption of peptides onto a closed membrane generates lateral pressure in the contacting lipid monolayer and lateral tension in the opposing monolayer. Our calculations predicted such asymmetric pressure/tension to greatly facilitate the formation of large metastable pores at any point of the membrane, regardless of the distance to the nearest peptide molecule. We therefore refer to this mechanism of pore formation as non-local. When the application of peptides in low concentration is followed by high concentration addition, multiple small metastable pores are predicted to form in the membrane in accordance with the local mechanism. This prevents the generation of a large difference in lateral pressure/tension, thus protecting the membrane from the formation of large pores. The results of the theoretical analysis agree with the experimental data of the companion paper.
Soft Condensed Matter (cond-mat.soft)
Counterflow of lattice polarons in harmonically confined optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-14 20:00 EST
Felipe Isaule, Abel Rojo-Francàs, Luis Morales-Molina, Bruno Juliá-Díaz
We study a mobile impurity in a one-dimensional harmonically confined optical lattice interacting repulsively with a bosonic bath. The behavior of the impurity across baths with superfluid and Mott-insulator domains is examined, including its full back-action effect on the bath. We characterize the bath-impurity phase diagram and reveal the appearance of a correlated counterflow phase, which we support with an analytical model for a mobile impurity-hole pair. This phase shows a combined insulator domain of unity filling but no independent domain of constant density. The transition to this phase features a sudden orthogonality catastrophe and the change of the shape of the impurity's profile to that of a free particle in an infinite square well. The findings of this work suggest the appearance of unconventional counterflow in trapped imbalanced atomic mixtures.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
10 pages, 6 figures
Broadband photoresponse enhancement by band engineering in Sb-doped MnBi2Te4
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Zixuan Xu, Haonan Chen, Jiayu Wang, Yicheng Mou, Yingchao Xia, Jiaming Gu, Yuxiang Wang, Qi Liu, Jiaqi Liu, Wenqing Song, Qing Lan, Tuoyu Zhao, Wu Shi, Cheng Zhang
Topological materials have attracted considerable attention for their potential in broadband and fast photoresponse, particularly in the infrared regime. However, the high carrier concentration in these systems often leads to rapid recombination of photogenerated carriers, limiting the photoresponsivity. Here, we demonstrate that Sb doping in MnBi2Te4 effectively reduces carrier concentration and suppresses electron-hole recombination, thereby significantly improving the optoelectronic performance across the visible to mid-infrared spectra. The optimally doped Mn(Bi0.82Sb0.18)2Te4 photodetector achieves a responsivity of 3.02 mA W-1 with a response time of 18.5 {}s at 1550 nm, and 0.795 mA W-1 with a response time of 9.0 {}s at 4 {}m. These values represent nearly two orders of magnitude improvement compared to undoped MnBi2Te4. Our results highlight band engineering as an effective strategy to enhance the infrared performance of topological material-based photodetectors, opening new avenues for high-sensitivity infrared detection.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 4 figures
Unexpected large electrostatic gating by pyroelectric charge accumulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Yicheng Mou, Qi Liu, Jiaqi Liu, Yingchao Xia, Zejing Guo, Wenqing Song, Jiaming Gu, Zixuan Xu, Wenbin Wang, Hangwen Guo, Wu Shi, Jian Shen, Cheng Zhang
Pyroelectricity refers to the accumulation of charges due to changes in the spontaneous polarization of ferroelectric materials when subjected to temperature variations. Typically, these pyroelectric charges are considered unstable and dissipate quickly through interactions with the external environment. Consequently, the pyroelectric effect has been largely overlooked in ferroelectric field-effect transistors. In this work, we leverage the van der Waals interface of hBN to achieve a substantial and long-term electrostatic gating effect in graphene devices via the pyroelectric properties of a ferroelectric LiNbO3 substrate. Upon cooling, the polarization change in LiNbO3 induces high doping concentrations up to 1013 cm-2 in the adjacent graphene. Through a combination of transport measurements and non-contact techniques, we demonstrate that the pyroelectric charge accumulation, as well as its enhancement in electric fields, are responsible for this unexpectedly high doping level. Our findings introduce a novel mechanism for voltage-free electrostatic gating control with long retention.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 4 figures
Coherent detection of the oscillating acoustoelectric effect in graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-14 20:00 EST
Yicheng Mou, Jiayu Wang, Haonan Chen, Yingchao Xia, Hailong Li, Qing Yan, Xue Jiang, Yijia Wu, Wu Shi, Hua Jiang, X. C. Xie, Cheng Zhang
In recent years, surface acoustic waves (SAWs) have emerged as a novel technique for generating quasiparticle transport and band modulation in condensed matter systems. SAWs interact with adjacent materials through piezoelectric and strain fields, dragging carriers in the direction of wave propagation. Most studies on the acoustoelectric effect have focused on the collective directional motion of carriers, which generates a steady electric potential difference, while the oscillating component from dynamic spatial charge modulation has remained challenging to probe. In this work, we report the coherent detection of oscillating acoustoelectric effect in graphene. This is achieved through the coherent rectification of spatial-temporal charge oscillation with electromagnetic waves emitted by interdigital transducers. We systematically investigate the frequency and gate dependence of rectified signals and quantitatively probe the carrier redistribution dynamics driven by SAWs. The observation of oscillating acoustoelectric effect provides direct access to the dynamic spatial charge modulation induced by SAWs through transport experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12 pages, 4 figures, to appear in PRL
Run-and-tumble particles with 1D Coulomb interaction: the active jellium model and the non-reciprocal self-gravitating gas
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Recently we studied \(N\) run-and-tumble particles in one dimension - which switch with rate \(\gamma\) between driving velocities \(\pm v_0\) - interacting via the long range 1D Coulomb potential (also called rank interaction), both in the attractive and in the repulsive case, with and without a confining potential. We extend this study in two directions. First we consider the same system, but inside a harmonic confining potential, which we call "active jellium". We obtain a parametric representation of the particle density in the stationary state at large \(N\), which we analyze in detail. Contrary to the linear potential, there is always a steady-state where the density has a bounded support. However, we find that the model still exhibits transitions between phases with different behaviors of the density at the edges, ranging from a continuous decay to a jump, or even a shock (i.e. a cluster of particles, which manifests as a delta peak in the density). Notably, the interactions forbid a divergent density at the edges, which may occur in the non-interacting case. In the second part, we consider a non-reciprocal version of the rank interaction: the \(+\) particles (of velocity \(+v_0\)) are attracted towards the \(-\) particles (of velocity \(-v_0\)) with a constant force \(b/N\), while the \(-\) particles are repelled by the \(+\) particles with a force of same amplitude. In order for a stationary state to exist we add a linear confining potential. We derive an explicit expression for the stationary density at large \(N\), which exhibits an explicit breaking of the mirror symmetry with respect to \(x=0\). This again shows the existence of several phases, which differ by the presence or absence of a shock at \(x=0\), with one phase even exhibiting a vanishing density on the whole region \(x>0\). Our analytical results are complemented by numerical simulations for finite \(N\).
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
39 pages, 6 figures
Excess energy and countercurrents after a quantum kick
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Nuria Santervás-Arranz, Massimiliano Stengel, Emilio Artacho
A quantum system of interacting particles under the effect of a static external potential is hereby described as kicked when that potential suddenly starts moving with a constant velocity v. If initially in a stationary state, the excess energy at any time after the kick equals \(v \langle P \rangle (t)\), with P being the total momentum of the system. If the system is finite and remains bound, the long time average of the excess energy tends to \(Mv^2\), with M the system's total mass, or a related expression if there is particle emission. \(Mv^2\) is twice what expected from an infinitely smooth onset of motion, and any monotonic onset is expected to increase the average energy to a value within both limits. In a macroscopic system, a particle flow emerges countering the potential's motion when electrons stay partially behind. For charged particles the described kinetic kick is equivalent to the kick given by the infinitely short electric-field pulse \(E = \frac{m}{q} v \delta (t)\) to the system at rest, useful as a formal limit in ultrafast phenomena. A linear-response analysis of low-v countercurrents in kicked metals shows that the coefficient of the linear term in v is the Drude weight. Non-linear in v countercurrents are expected for insulators through the electron-hole excitations induced by the kick, going as \(v^3\) at low v for centrosymmetric ones. First-principles calculations for simple solids are used to ratify those predictions, although the findings apply more generally to systems such as Mott insulators or cold lattices of bosons or fermions.
Materials Science (cond-mat.mtrl-sci)
10 pages, 3 figures, 6 pdfs with the figures
Extinction and Metastability of Pheromone-Roads in Stochastic Models for Foraging Walks of Ants
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Saori Morimoto, Makoto Katori, Hiraku Nishimori
Macroscopic changes of group behavior of eusocial insects are studied from the viewpoint of non-equilibrium phase transitions. Recent combined study of experiments and mathematical modeling by the group led by the third author suggests that a species of garden ant switches the individual foraging walk from pheromone-mediated to visual-cues-mediated depending on situation. If an initial pheromone-road between the nest and food sources is a detour, ants using visual cues can pioneer shorter paths. These shorter paths are reinforced by pheromone secreted by following ants, and then the detour ceases to exist. Once the old pheromone-road extincts, there will be almost no chance to reconstruct it. Hence the extinction of pheromone-road is expected to be regarded as a phase transition to an absorbing state. We propose a discrete-time model on a square lattice consisting of switching random walks interacting though time-dependent pheromone field. The numerical study shows that the critical phenomena of the present extinction transitions of pheromone-roads do not seem to belong to the directed percolation universality class associated with the usual absorbing-state transition. The new aspects are cased by the coexistence and competition with newly creating pheromone-roads. In a regime in the extinction phase, the annihilating road shows metastability and takes long time-period to be replaced by a new road.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO), Populations and Evolution (q-bio.PE)
LaTeX 18 pages, 8 figures
DiffRenderGAN: Addressing Training Data Scarcity in Deep Segmentation Networks for Quantitative Nanomaterial Analysis through Differentiable Rendering and Generative Modelling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Dennis Possart, Leonid Mill, Florian Vollnhals, Tor Hildebrand, Peter Suter, Mathis Hoffmann, Jonas Utz, Daniel Augsburger, Mareike Thies, Mingxuan Wu, Fabian Wagner, George Sarau, Silke Christiansen, Katharina Breininger
Nanomaterials exhibit distinctive properties governed by parameters such as size, shape, and surface characteristics, which critically influence their applications and interactions across technological, biological, and environmental contexts. Accurate quantification and understanding of these materials are essential for advancing research and innovation. In this regard, deep learning segmentation networks have emerged as powerful tools that enable automated insights and replace subjective methods with precise quantitative analysis. However, their efficacy depends on representative annotated datasets, which are challenging to obtain due to the costly imaging of nanoparticles and the labor-intensive nature of manual annotations. To overcome these limitations, we introduce DiffRenderGAN, a novel generative model designed to produce annotated synthetic data. By integrating a differentiable renderer into a Generative Adversarial Network (GAN) framework, DiffRenderGAN optimizes textural rendering parameters to generate realistic, annotated nanoparticle images from non-annotated real microscopy images. This approach reduces the need for manual intervention and enhances segmentation performance compared to existing synthetic data methods by generating diverse and realistic data. Tested on multiple ion and electron microscopy cases, including titanium dioxide (TiO\(_2\)), silicon dioxide (SiO\(_2\))), and silver nanowires (AgNW), DiffRenderGAN bridges the gap between synthetic and real data, advancing the quantification and understanding of complex nanomaterial systems.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV), Machine Learning (cs.LG)
Journey from the Wilson exact RG towards the Wegner-Morris Fokker-Planck RG and the Carosso field-coarsening via Langevin stochastic processes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Within the Wilson RG of 'incomplete integration' as a function of the RG-time \(t\), the non-linear differential RG flow for the energy \(E_t[\phi(.)]\) translates for the probability distribution $P_t[(.)] e^{- E_t[(.)]} $ into the linear Fokker-Planck RG flow associated to independent non-identical Ornstein-Uhlenbeck processes for the Fourier modes. The corresponding Langevin stochastic differential equation for the real-space field \(\phi_t(\vec x)\) can be then interpreted within the Carosso perspective as genuine infinitesimal coarsening-transformations that are the analog of spin-blocking, and whose irreversible character is essential to overcome the paradox of the naive description of the Wegner-Morris RG flow as a mere infinitesimal change of variables in the partition function integral. This interpretation suggests to consider new RG-schemes, in particular the Carosso RG where the Langevin SDE corresponds to the well known stochastic heat equation or the Edwards-Wilkinson dynamics. We stress the advantages of this stochastic formulation of exact RG flows. While statistical field theory is usually written in infinite space, we focus here on the formulation on a large volume \(L^d\) with periodic boundary conditions, in order to distinguish between extensive and intensives observables while keeping the translation-invariance. Since the empirical magnetization $m_e _{L^d} d^d x (x) $ is an intensive variable corresponding to the zero-momentum Fourier coefficient of the field, its probability distribution \(p_L(m_e)\) can be obtained from the gradual integration over all the other Fourier coefficients associated to non-vanishing-momenta via exact differential RG, in order to obtain the large deviation properties with respect to the volume \(L^d\).
Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)
39 pages
Thermodynamics of multi-colored loop models in three dimensions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-14 20:00 EST
Soumya Kanti Ganguly, Sumanta Mukherjee, Chandan Dasgupta
We study order-disorder transitions in three-dimensional loop models using Monte Carlo simulations. We show that the nature of the transition is intimately related to the nature of the loops. The symmetric loops undergo a first order phase transition, while the non-symmetric loops show a second-order transition. The critical exponents for the non-symmetric loops are calculated. In three dimensions, the regular loop model with no interactions is dual to the XY model. We argue that, due to interactions among the colors, the specific heat exponent is found to be different from that of the regular loop model. The continuous nature of the transition is altered to a discontinuous one due to the strong inter-color interactions.
Statistical Mechanics (cond-mat.stat-mech)
Frustration-driven topological textures on the honeycomb lattice: antiferromagnetic meron-antimeron and skyrmion crystals emerging from spiral spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
M. Mohylna, F. A. Gómez Albarracín, M. Žukovič, H. Diego Rosales
Skyrmions -topologically nontrivial magnetic quasi-particles- can emerge in two-dimensional chiral magnets due to moderate or high strength of the Dzyaloshinskii-Moriya (DM) interaction. In this work, we show that the inclusion of weak next-nearest-neighbor DM interaction in the frustrated \(J_1\)-\(J_2\) honeycomb-lattice Heisenberg antiferromagnet leads to the emergence of field-induced incommensurate antiferromagnetic meron-antimeron pairs and antiferromagnetic skyrmion structures. Using the Luttinger-Tisza approximation and large-scale Monte Carlo simulations, we report that for lower frustration values, antiferromagnetic meron-antimeron pair crystal and gas phases emerge within a small magnetic field window. In these meron phases, the fundamental unit consists of a meron-antimeron pair residing on different sublattices of the honeycomb lattice, even in the gas phase, where they exhibit greater mobility. For larger frustration, a two-layer-like three-sublattice antiferromagnetic skyrmion crystal phase is stabilized over a wider magnetic field range. At lower temperatures, this region splits into two distinct antiferromagnetic skyrmion phases with skyrmions of different sizes, reflecting the influence of frustration and thermal effects on the stabilization of these topological textures. Interestingly, both meron and skyrmion low-temperature phases connect to spiral spin liquid phases of the honeycomb lattice at higher temperatures. Additionally, we analyze the emergent single-\(q\) and double-\(q\) phases at low temperatures, constructing a comprehensive phase diagram.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
17 pages, 12 figures
Collective migration and topological phase transitions in confluent epithelia
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-14 20:00 EST
Leonardo Puggioni, Dimitrios Krommydas, Luca Giomi
Collective epithelial migration leverages on topological rearrangements of the intercellular junctions, which allow cells to intercalate without loosing confluency. In silico studies have provided a clear indication that this process could occur via a two-step phase transition, where a hierarchy of topological excitations progressively transforms an epithelial layer from a crystalline solid to an isotropic liquid, via an intermediate hexatic liquid crystal phase. Yet, the fundamental mechanism behind this process and its implications for collective cell behavior are presently unknown. In this article, we show that the onset of collective cell migration in cell-resolved models of epithelial layers takes place via an activity-driven melting transition, characterized by an exponentially-divergent correlation length across the solid/hexatic phase boundary. Using a combination of numerical simulations and Renormalization Group analysis, we show that the availability of topologically distinct rearrangements - known as T1 and T2 processes - and of a non-thermal route to melting, renders the transition significantly more versatile and tunable than in two-dimensional passive matter. Specifically, the relative frequency of T1 and T2 processes and of the "bare" stiffness of the cell layer affect the divergence of positional correlations within a well-defined spectrum of critical behaviors. Suppressing T1 processes, changes the nature of the transition by preventing collective migration in favor of a cellular analog of surface sublimation.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
Spin Pumping in Magnetostrictive Galfenol Interfaced with Ta
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Ajit Kumar Sahoo, Suchetana Mukhopadhyay, Bikram Baghira, Jeyaramane Arout Chelvane, Jyoti Ranjan Mohanty, Anjan Barman
In view of their advantages for memory and storage applications, the quest to find suitable magnetic thin film heterostructures that can exhibit strong spin pumping effect persists in the scientific community. Here, we investigate the spin pumping phenomenon in Galfenol (FeGa) thin films by systematically varying the thickness of heavy metallic Ta underlayer (UL). Films exhibit soft magnetic properties with a bcc-phase and a notably low Gilbert damping is obtained for FeGa on Si (100). Further, we explore magnetic precessional dynamics of Ta/FeGa films using the time-resolved magneto-optical Kerr effect technique, revealing the presence of a resonant Kittel mode and additional strain-induced modes. The lowest value of effective Gilbert damping is obtained as \(\sim\) 0.015, which rises by $$65% as the thickness of UL increases. Spin pumping and two-magnon scattering mechanisms are validated using a ballistic spin transport model. We find an overall effective spin mixing conductance value of $$5.48 \(\times\) \(10^{15}\) cm\(^{-2}\), which is the highest value ever reported in magnetostrictive films. Additionally, we performed micromagnetic simulations to understand the effect of tilted magnetic anisotropy on the formation of magnetic modes in these films. These findings in FeGa films establish it as an effective spin source material and offer innovative ideas to control spin-wave propagation and diverse applications in straintronics.
Materials Science (cond-mat.mtrl-sci)
17
Advanced Functional Materials, 2025
Memorization and Generalization in Generative Diffusion under the Manifold Hypothesis
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-14 20:00 EST
Beatrice Achilli, Luca Ambrogioni, Carlo Lucibello, Marc Mézard, Enrico Ventura
We study the memorization and generalization capabilities of a Diffusion Model (DM) in the case of structured data defined on a latent manifold. We specifically consider a set of \(P\) mono-modal data points in \(N\) dimensions lying on a latent subspace of dimension \(D = \alpha_D N\), according to the Hidden Manifold Model (HMM). Our analysis leverages the recently introduced formalism based on the statistical physics of the Random Energy Model (REM). We provide evidence for the existence of an onset time \(t_{o} > t_c\) when traps appear in the potential without affecting the typical diffusive trajectory. The size of the basins of attraction of such traps is computed as a function of time. Moreover, we derive the collapse time \(t_{c}\) at which trajectories fall in the basin of one of the training points, implying memorization. An explicit formula for \(t_c\) is given as a function of \(P\) and the ratio \(\alpha_D\), proving that the curse of dimensionality issue does not hold for highly structured data, i.e. \(\alpha_D\ll 1\), regardless of the non-linearity of the manifold surface. We also prove that collapse coincides with the condensation transition in the REM. Eventually, the degree of generalization of DMs is formulated in terms of the Kullback-Leibler divergence between the exact and the empirical distribution of the sampled configurations: we show the existence of an additional time \(t_{g}<t_{c}<t_{o}\) such that the distance between the empirical measure of the data and the ground-truth is minimal. Counter-intuitively, the best generalization performance is found within the memorization phase of the model. We conclude that the generalization performance of DMs benefit from highly structured data since \(t_g\) approaches zero faster than \(t_c\) when \(\alpha_D \rightarrow 0\).
Disordered Systems and Neural Networks (cond-mat.dis-nn)
26 pages, 8 figures
Pressure-Tuned Magnetism and Bandgap Modulation in Layered Fe-Doped CrCl3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-14 20:00 EST
Aya Ali, Govindaraj Lingannan, Lukas Gries, Md Ezaz Hasan Khan, Anas Abutaha, Kei Uemura, Masaki Mito, Vladislav Borisov, Anna Delin, Olle Eriksson, Ruediger Klingeler, Mahmoud Abdel-Hafiez
We explore the structural, magnetic, vibrational and optical band gap properties under varying pressures. By integrating first-principles calculations with experimental techniques, including Raman spectroscopy, photoluminescence (PL), uniaxial pressure studies (thermal expansion), and magnetization measurements, we unveil the intricate pressure-induced transformations in Fe-doped CrCl3, shedding light on its structural, electronic, and magnetic evolution. At ambient pressure, Raman spectra confirm all expected Raman-active modes, which exhibit blue shifts with increasing pressure. The PL measurements demonstrate an optical bandgap of 1.48 eV at ~0.6 GPa, with a progressive increase in the bandgap under pressure, transitioning slower above 6 GPa due to an isostructural phase transition. Magnetization results under pressure shows two competing magnetic components (FM and AFM) at ambient conditions, where at the lowest temperature and applied field, the FM component dominates. The presence of competing FM and AFM energy scales is confirmed by Grueneisen analysis of the thermal expansion and their uniaxial pressure dependence is determined. The experimental findings agree with theoretical results based on Density functional theory (DFT). In the experiments, we observe a pressure-enhanced ferromagnetic interlayer coupling that is followed by the stabilization of antiferromagnetic ordering, due to weakened direct interlayer interactions. Above 1.2 GPa the FM component of the magnetism is gone in the experimental observations, which is also in good agreement with DFT based theory. The findings reported here underscore the potential of CrCl3 for use in pressure-tunable magnetic and optoelectronic applications, where, e.g., the delicate balance between FM and AFM configurations could have potential for sensor applications.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 11 figures
Spin wave interactions in the pyrochlore Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-14 20:00 EST
V. V. Jyothis, Kallol Mondal, Himanshu Mavani, V. Ravi Chandra
We study the effect of magnon interactions on the spin wave spectra of the All-in-All-out phase of the pyrochlore nearest neighbour antiferromagnet with a Dzyaloshinskii-Moriya interaction \(D\). The leading order corrections to spin wave energies indicate a significant renormalisation for commonly encountered strengths of the Dzyaloshinskii-Moriya term. For low values of \(D\) we find a potential instability of the phase itself, indicated by the renormalisation of magnon frequencies to negative values. We have also studied the renormalized spectra in the presence of magnetic fields along three high symmetry directions of the lattice, namely the \([111]\), \([100]\) and \([110]\) directions. Generically, we find that for a fixed value of the Dzyaloshinskii-Moriya interaction renormalized spectra for the lowest band decrease with an increasing strength of the field. We have also analyzed the limits of the two magnon continuum and probed the possibility of magnon decay. For a range of \(D\) and the field strength we identify possible parameter regimes where the decay of the higher bands of the system are kinematically allowed.
Strongly Correlated Electrons (cond-mat.str-el)
Superspin Renormalization and Slow Relaxation in Random Spin Systems
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-14 20:00 EST
Yi J. Zhao, Samuel J. Garratt, Joel E. Moore
We develop an excited-state real-space renormalization group (RSRG-X) formalism to describe the dynamics of conserved densities in randomly interacting spin-\(\frac{1}{2}\) systems. Our formalism is suitable for systems with \(\textrm{U}(1)\) and \(\mathbb{Z}_2\) symmetries, and we apply it to chains of randomly positioned spins with dipolar \(XX+YY\) interactions, as arise in Rydberg quantum simulators and other platforms. The formalism generates a sequence of effective Hamiltonians which provide approximate descriptions for dynamics on successively smaller energy scales. These effective Hamiltonians involve ``superspins'': two-level collective degrees of freedom constructed from (anti)aligned microscopic spins. Conserved densities can then be understood as relaxing via coherent collective spin flips. For the well-studied simpler case of randomly interacting nearest-neighbor \(XX+YY\) chains, the superspins reduce to single spins. Our formalism also leads to a numerical method capable of simulating the dynamics up to an otherwise inaccessible combination of large system size and late time. Focusing on disorder-averaged infinite-temperature autocorrelation functions, in particular the local spin survival probability \(\overline{S_p}(t)\), we demonstrate quantitative agreement in results between our algorithm and exact diagonalization (ED) at low but nonzero frequencies. Such agreement holds for chains with nearest-neighbor, next-nearest-neighbor, and long-range dipolar interactions. Our results indicate decay of \(\overline{S_p}(t)\) slower than any power law and feature no significant deviation from the \(\sim 1/ \log^2(t)\) asymptote expected from the infinite-randomness fixed-point of the nearest-neighbor model. We also apply the RSRG-X formalism to two-dimensional long-range systems of moderate size and find slow late-time decay of \(\overline{S_p}(t)\).
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
27 pages, 13 figures