CMP Journal 2025-02-27
Statistics
Physical Review Letters: 11
Physical Review X: 1
arXiv: 63
Physical Review Letters
Symmetry Induced Enhancement in Finite-Time Thermodynamic Trade-Off Relations
Research article | Nonequilibrium & irreversible thermodynamics | 2025-02-27 05:00 EST
Ken Funo and Hiroyasu Tajima
Symmetry imposes constraints on open quantum systems, affecting the dissipative properties in nonequilibrium processes. Superradiance is a typical example in which the decay rate of the system is enhanced via a collective system-bath coupling that respects permutation symmetry. Such a model has also been applied to heat engines. However, a generic framework that addresses the impact of symmetry in finite-time thermodynamics is not well established. Here, we show a symmetry-based framework that describes the fundamental limit of collective enhancement in finite-time thermodynamics. Specifically, we derive a general upper bound on the average jump rate, which quantifies the fundamental speed set by thermodynamic speed limits and trade-off relations. We identify the symmetry condition that achieves the obtained bound, and explicitly construct an open quantum system model that goes beyond the enhancement realized by the conventional superradiance model.
Phys. Rev. Lett. 134, 080401 (2025)
Nonequilibrium & irreversible thermodynamics, Open quantum systems, Quantum thermodynamics, Quantum heat engines & refrigerators, Quantum master equation
Speeding Up Quantum Measurement Using Space-Time Trade-Off
Research article | Quantum computation | 2025-02-27 05:00 EST
Christopher Corlett, Ieva Čepaitė, Andrew J. Daley, Cica Gustiani, Gerard Pelegrí, Jonathan D. Pritchard, Noah Linden, and Paul Skrzypczyk
A new scheme can speed up quantum measurement in different physical platforms through a space-time trade-off -- using additional ancillary qubits in place of longer measurement time.
Phys. Rev. Lett. 134, 080801 (2025)
Quantum computation, Quantum error correction, Quantum information architectures & platforms, Quantum information processing, Quantum information theory, Quantum measurements, Quantum protocols, Qubits
Possible Implications of QCD Axion Dark Matter Constraints from Helioscopes and Haloscopes for the String Theory Landscape
Research article | Axions | 2025-02-27 05:00 EST
Naomi Gendler and David J. E. Marsh
Laboratory experiments have the capacity to detect the QCD axion in the next decade, and precisely measure its mass, if it composes the majority of the dark matter. In type IIB string theory on Calabi-Yau threefolds in the geometric regime, the QCD axion mass, \({m}_{a}\), is strongly correlated with the topological Hodge number \({h}^{1,1}\). We compute \({m}_{a}\) in a scan of 185965 compactifications of type IIB string theory on toric hypersurface Calabi-Yau threefolds. We compute the range of \({h}^{1,1}\) probed by different experiments under the condition that the QCD axion can provide the observed dark matter density with minimal fine-tuning. Taking the experiments DMRadio, ADMX, MADMAX, and BREAD as indicative on different mass ranges, the \({h}^{1,1}\) distributions peak near \({h}^{1,1}=24.9\), 65.4, 196.8, and 310.9, respectively. We furthermore conclude that, without severe fine-tuning, detection of the QCD axion as dark matter at any mass disfavors 80% of models with \({h}^{1,1}=491\), which is thought to have the most known Calabi-Yau threefolds. Measurement of the solar axion mass with IAXO is the dominant probe of all models with \({h}^{1,1}\gtrsim 250\). This Letter demonstrates the immense importance of axion detection in experimentally constraining the string landscape.
Phys. Rev. Lett. 134, 081602 (2025)
Axions, Compactification, Cosmology, Dark matter direct detection, Field & string theory models & techniques, Hypothetical particle physics models, Particle dark matter, Quantum gravity, String phenomenology, Strings & branes
Minimizing Selection Bias in Inclusive Jets in Heavy-Ion Collisions with Energy Correlators
Research article | Jet quenching | 2025-02-27 05:00 EST
Carlota Andres, Jack Holguin, Raghav Kunnawalkam Elayavalli, and Jussi Viinikainen
The first-ever measurement of energy correlators within inclusive jets produced in heavy-ion collisions, revealed by the CMS Collaboration, shows a clear enhancement at large angles relative to the proton-proton (p-p) baseline. However, interpreting this enhancement is complicated due to selection bias from energy loss, which also distorts the energy correlator heavy-ion to p-p ratio in the hadronization region, hindering our understanding of parton/hadron dynamics in a colored medium. In this Letter, we introduce a new ratio of energy correlator observables that removes the leading effects of selection bias from the two-point energy correlator spectrum (E2C). pythia and herwig simulations show that the impact of selection bias in the E2C is reduced by an order of magnitude, while sensitivity to any other medium modifications is retained. This quantity can be obtained directly from the experimental measurements presented by CMS, as illustrated in an accompanying note [C. Andres and J. Holguin, arXiv:2409.07526].
Phys. Rev. Lett. 134, 082303 (2025)
Jet quenching, Quark-gluon plasma, Relativistic heavy-ion collisions
Improved Limit on Neutrinoless Double Beta Decay of \(^{100}\mathrm{Mo}\) from AMoRE-I
Research article | Double beta decay | 2025-02-27 05:00 EST
A. Agrawal et al. (AMoRE Collaboration)
et al.Observations of molybdenum nuclei have revealed no signs of a speculative nuclear decay called neutrinoless double-beta decay, setting a strong constraint on this process.
Phys. Rev. Lett. 134, 082501 (2025)
Double beta decay, Neutrinoless double beta decay, Nuclear structure & decays
Atomic-Scale On-Demand Photon Polarization Manipulation with High-Efficiency for Integrated Photonic Chips
Research article | Integrated optics | 2025-02-27 05:00 EST
Yunning Lu, Zeyang Liao, and Xue-Hua Wang
In order to overcome the challenge of lacking polarization encoding in integrated quantum photonic circuits, we propose a scheme to realize arbitrary polarization manipulation of a single photon by integrating a single quantum emitter in a photonic waveguide. In our scheme, one transition path of the three-level emitter is designed to simultaneously couple with two orthogonal polarization degenerate modes in the waveguide with adjustable coupling strengths, and the other transition path of the three-level emitter is driven by an external coherent field. The proposed polarization converter has several advantages, including arbitrary polarization conversion for any input polarization, tunable working frequency, excellent antidissipation ability with high-conversion efficiency, and atomic-scale size. Our Letter provides an effective solution to enable the polarization encoding of photons that can be applied in the integrated quantum photonic circuits, and will boost quantum photonic chips.
Phys. Rev. Lett. 134, 083601 (2025)
Integrated optics, Quantum description of light-matter interaction, Quantum optics
Experimental Generation of Extreme Electron Beams for Advanced Accelerator Applications
Research article | Beam dynamics | 2025-02-27 05:00 EST
C. Emma, N. Majernik, K. K. Swanson, R. Ariniello, S. Gessner, R. Hessami, M. J. Hogan, A. Knetsch, K. A. Larsen, A. Marinelli, B. O'Shea, S. Perez, I. Rajkovic, R. Robles, D. Storey, and G. Yocky
Record high-intensity electron beams with high peak current and petawatt peak power have been successfully generated, opening up a new avenue to study high-intensity beam-light and beam-matter interactions.
Phys. Rev. Lett. 134, 085001 (2025)
Beam dynamics
Renormalized Classical Spin Liquid on the Ruby Lattice
Research article | Quantum spin liquid | 2025-02-27 05:00 EST
Zhenjiu Wang and Lode Pollet
The recent experimental detection of the onset of a dynamically prepared, gapped \({Z}_{2}\) quantum spin liquid on the ruby lattice brought the physics of frustrated magnetism and lattice gauge theory to Rydberg tweezer arrays [Semeghini et al., Probing topological spin liquids on a programmable quantum simulator, Science 374, 1242 (2021)]. The thermodynamic properties of such models remain inadequately addressed, yet knowledge thereof is indispensable if one wants to prepare large, robust, and long-lived quantum spin liquids. Using large scale quantum Monte Carlo simulations we find in the PXP model a renormalized classical spin liquid with constant entropy density \(S/N\) approaching \(\mathrm{ln}(2)/6\) in the thermodynamic limit for all moderate and large values of the detuning $$ and starting from \(T/\mathrm{\Omega }\sim 0.5\) (in units of the Rabi frequency \(\mathrm{\Omega }\)) down to the lowest temperatures we could simulate, \(T/\mathrm{\Omega }\sim 0.01\). With van der Waals interactions, constant entropy plateaus are still found but its value shifts with $$. We comment on the implications of the adiabatic approximation to the dynamical ramps for the electric degrees of freedom, which leads to a reinterpretation of the experimental observations.
Phys. Rev. Lett. 134, 086601 (2025)
Quantum spin liquid, Rydberg gases, Ultracold gases
Electromagnon Signatures of a Metastable Multiferroic State
Research article | Exotic phases of matter | 2025-02-27 05:00 EST
Blake S. Dastrup, Zhuquan Zhang, Peter R. Miedaner, Yu-Che Chien, Young Sun, Yan Wu, Huibo Cao, Edoardo Baldini, and Keith A. Nelson
Magnetoelectric multiferroic materials, particularly type-II multiferroics where ferroelectric polarizations arise from magnetic order, offer significant potential for the simultaneous control of magnetic and electric properties. However, it remains an open question as to how the multiferroic ground states are stabilized on the free-energy landscape in the presence of intricate competition between the magnetoelectric coupling and thermal fluctuations. In this work, by using terahertz time-domain spectroscopy in combination with an applied magnetic field, photoexcitation, and single-shot detection, we reveal the spectroscopic signatures of a magnetic-field-induced metastable multiferroic state in a hexaferrite. This state remains robust until thermal influences cause the sample to revert to the original paraelectric state. Our findings shed light on the emergence of metastable multiferroicity and its interplay with thermal dynamics.
Phys. Rev. Lett. 134, 086706 (2025)
Exotic phases of matter, Magnetic phase transitions, Magnons, Helimagnets, Multiferroics, Terahertz spectroscopy
Charge Dynamics of an Unconventional Three-Dimensional Charge Density Wave in Kagome FeGe
Research article | Charge density waves | 2025-02-27 05:00 EST
Shaohui Yi, Zhiyu Liao, Qi Wang, Haiyang Ma, Jianpeng Liu, Xiaokun Teng, Bin Gao, Pengcheng Dai, Yaomin Dai, Jianzhou Zhao, Yanpeng Qi, Bing Xu, and Xianggang Qiu
We report on the charge dynamics of kagome FeGe, an antiferromagnet with a charge density wave (CDW) transition at \({T}_{\mathrm{CDW}}\simeq 105\text{ }\text{ }\mathrm{K}\), using polarized infrared spectroscopy and band structure calculations. We reveal pronounced optical anisotropy along the \(a\) and \(c\) axis, as well as an unusual response associated with three-dimensional CDW order. Above \({T}_{\mathrm{CDW}}\), there is a notable transfer of spectral weight (SW) from high to low energies, promoted by the magnetic splitting-induced shift in bands. Across the CDW transition, we observe a sudden SW transfer from low to high energies over a broad range, along with the emergence of new excitations around \(1200\text{ }\text{ }{\mathrm{cm}}^{- 1}\). These results contrast with observations from other kagome metals like \({\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}\), where the nesting of VHSs leads to a clear CDW gap feature. Instead, our findings can be accounted for by a \(2\times{}2\times{}2\) CDW ground state driven by a first-order structural transition involving large partial Ge1 dimerization. Our Letter thus unveils a complex interplay among structure, magnetism, and charge order, offering valuable insights for a comprehensive understanding of CDW order in FeGe.
Phys. Rev. Lett. 134, 086902 (2025)
Charge density waves, Optical conductivity, Phase transitions by order, Strongly correlated systems, Infrared spectroscopy
Parameter Inference and Nonequilibrium Identification for Markov Networks Based on Coarse-Grained Observations
Research article | Nonequilibrium & irreversible thermodynamics | 2025-02-27 05:00 EST
Bingjie Wu and Chen Jia
Most experiments can only detect a set of coarse-grained clusters of a molecular system, while the internal microstates are often inaccessible. Here, based on an infinitely long coarse-grained trajectory, we obtain a set of sufficient statistics that extracts all statistic information of coarse-grained observations. Based on these sufficient statistics, we set up a theoretical framework of parameter inference and nonequilibrium identification for a general Markov network with an arbitrary number of microstates and arbitrary coarse-grained partitioning. Our framework can be used to identify whether the sufficient statistics are enough for empirical estimation of all unknown parameters and we can also provide a quantitative criterion that reveals nonequilibrium. Our nonequilibrium criterion generalizes the one obtained [J. Chem. Phys. 132, 041102 (2010)] for a three-state system with two coarse-grained clusters and is capable of detecting a larger nonequilibrium region compared to the classical criterion based on autocorrelation functions.
Phys. Rev. Lett. 134, 087103 (2025)
Nonequilibrium & irreversible thermodynamics, Nonequilibrium statistical mechanics, Nonequilibrium systems, Coarse graining, Markovian processes
Physical Review X
Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
Research article | Electrical properties | 2025-02-27 05:00 EST
Dacen Waters, Anna Okounkova, Ruiheng Su, Boran Zhou, Jiang Yao, Kenji Watanabe, Takashi Taniguchi, Xiaodong Xu, Ya-Hui Zhang, Joshua Folk, and Matthew Yankowitz
Electric-field control of topological states in a pentalayer graphene moiré system reveals tunable quantum phases, correlated insulating states, and evidence of fractional charge quasiparticles.
Phys. Rev. X 15, 011045 (2025)
Electrical properties, Strongly correlated systems, Topological materials
arXiv
Topolectrical circuits \(-\) recent experimental advances and developments
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Haydar Sahin, Mansoor B. A. Jalil, Ching Hua Lee
Metamaterials serve as versatile platforms for demonstrating condensed matter physics and non-equilibrium phenomena, with electrical circuits emerging as a particularly compelling medium. This review highlights recent advances in the experimental circuit realizations of topological, non-Hermitian, non-linear, Floquet and other notable phenomena. Initially performed mostly with passive electrical components, topolectrical circuits have evolved to incorporate active elements such as operational amplifiers and analog multipliers that combine to form negative impedance converters, complex phase elements, high-frequency temporal modulators and self-feedback mechanisms. This review provides a summary of these contemporary studies and discusses the broader potential of electrical circuits in physics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Applied Physics (physics.app-ph)
39 pages, 11 figures
Strong Coupling of Nanomechanical Vibrations to Individual Two-Level Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
M. Yuksel, M. P. Maksymowych, O. A. Hitchcock, F. M. Mayor, N. R. Lee, M. I. Dykman, A. H. Safavi-Naeini, M. L. Roukes
Atomic-scale defects behaving as two-level systems (TLSs) are crucial to the physics of modern quantum devices. Here, we study interactions between individual TLS defects and the mechanical vibrations of a nanoelectromechanical systems (NEMS) resonator. By applying a mechanical strain, we tune individual TLS onto resonance with the NEMS and observe strong coupling. By adjusting phonon number, we reveal the nonlinear energy levels of the hybridized system and confirm single-phonon nonlinearity. We also observe fluctuations between hybridized and bare resonance states as the TLS fluctuates between on- and off-resonance. These quintessential quantum effects emerge directly from intrinsic material properties, without requiring external electromagnetic systems or complex quantum circuits. Our work establishes a platform for exploring and manipulating TLS-phonon interactions in the single-phonon regime.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
Altermagnetic nanotextures revealed in bulk MnTe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Rikako Yamamoto, Luke Alexander Turnbull, Marcus Schmidt, José Claudio Corsaletti Filho, Hayden Jeffrey Binger, Marisel Di Pietro Martínez, Markus Weigand, Simone Finizio, Yurii Prots, George Matthew Ferguson, Uri Vool, Sebastian Wintz, Claire Donnelly
With many candidate altermagnetic materials, MnTe has emerged as one of the most promising systems, with growing experimental evidence for altermagnetic phenomena. So far, the majority of measurements have been performed on thin-films, or have involved surface measurements. However, the question of altermagnetic order in the bulk system - in the absence of substrate or surface effects - remains. Here we show evidence for bulk altermagnetism in single crystal MnTe, through spectroscopic X-ray microscopy. By performing nanoscale X-ray magnetic circular dichroic (XMCD) imaging in transmission on a 200 nm thick lamella, we observe domains and magnetic textures with a spectroscopic signature characteristic of altermagnetic order, thereby confirming the intrinsic nature of altermagnetism in MnTe. Quantitative analysis of the XMCD signal reveals an excellent agreement with predicted signals, establishing that the altermagnetic order exists throughout the thickness of the lamella and confirming the intrinsic, bulk nature of the state. With these results, we demonstrate that transmission XMCD spectroscopic imaging is a robust, quantitative technique to probe altermagnetic order, providing a means to probe individual altermagnetic domains within complex configurations. This ability to investigate, and characterise altermagnetic order in bulk crystals represents an important tool for the exploration of altermagnetism across a wide range of candidate materials, of key importance for the development of future technologies.
Materials Science (cond-mat.mtrl-sci)
Mind the Gap: Bridging the Divide Between AI Aspirations and the Reality of Autonomous Characterization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Grace Guinan, Addison Salvador, Michelle A. Smeaton, Andrew Glaws, Hilary Egan, Brian C. Wyatt, Babak Anasori, Kevin R. Fiedler, Matthew J. Olszta, Steven R. Spurgeon
What does materials science look like in the "Age of Artificial Intelligence?" Each materials domain-synthesis, characterization, and modeling-has a different answer to this question, motivated by unique challenges and constraints. This work focuses on the tremendous potential of autonomous characterization within electron microscopy. We present our recent advancements in developing domain-aware, multimodal models for microscopy analysis capable of describing complex atomic systems. We then address the critical gap between the theoretical promise of autonomous microscopy and its current practical limitations, showcasing recent successes while highlighting the necessary developments to achieve robust, real-world autonomy.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
33 pages, 6 figures
Formation of Complex Discrete Time Crystals with Ultracold Atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-27 20:00 EST
Weronika Golletz, Krzysztof Sacha
We study discrete time crystal formation in a system driven periodically by an oscillating atomic mirror, consisting of two distinct ultracold atomic clouds in the presence of a gravitational field. The intra-species interactions are weak and attractive, while the inter-species interactions are infinitely strong and repulsive. The clouds are arranged in a one-dimensional stack, where the bottom cloud bounces on an oscillating atomic mirror, which effectively acts as a driving force for the upper cloud due to the infinite inter-species repulsion. Using a Jastrow-like variational ansatz for the many-body wavefunction, we show that sufficiently strong attractive intra-species interactions drive each subsystem to spontaneously break discrete time translation symmetry, resulting in the formation of a complex discrete time crystal evolving with a period different than the driving period. Since the bottom cloud serves as the effective periodic driving for the upper cloud, this leads to a cascade of spontaneous symmetry breaking. With increasing intra-species interactions, we first observe a pronounced effect of spontaneous time translation symmetry breaking in the upper cloud, followed by a similar effect in the lower atomic cloud.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
7 pages, 3 figures
Meta-GGA dielectric-dependent and range-separated screened hybrid functional for reliable prediction of material properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Subrata Jana, Abhishek Bhattacharjee, Suman Mahakal, Szymon Smiga, Prasanjit Samal
We propose a range-separated hybrid exchange-correlation functional
to calculate solid-state material properties. The functional mixes
Hartree-Fock exchange with the semilocal exchange of the
meta-generalized gradient approximation (meta-GGA) and the fraction of
Hartree-Fock exchange is determined from the dielectric function.
First-principles calculations and comparison with other meta-GGA
approximations show that the functional leads to reasonably good
performance for the band gap and optical properties. We also show that
the present functional also successfully resolves the well-known
band gap problem'' of narrow gap Cu-based semiconductors, such as Cu3SbSe4 and Cu3AsSe4, where, in general, a considerably large band inversion energy leads to afalse''
negative or metallic band gap for all other methods. Furthermore,
reasonable accuracy for the occupied d-bands and transition energies is
also obtained for bulk solids. Thus, overall, our results demonstrate
the predictive power of range-separated meta-GGA hybrid functionals for
quantum materials simulations.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Physical Review B (2025)
Metal-organic chemical vapor deposition of MgGeN2 films on GaN and sapphire
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Chenxi Hu, Vijay Gopal Thirupakuzi Vangipuram, Christopher Chae, Ilteris K. Turan, Nichole Hoven, Walter R.L. Lambrecht, Jinwoo Hwang, Yumi Ijiri, Hongping Zhao, Kathleen Kash
MgGeN2 films were synthesized using metal-organic chemical vapor deposition on GaN/c-sapphire templates and c-plane sapphire substrates. Energy-dispersive X-ray spectroscopy was used to estimate the cation composition ratios. To mitigate magnesium evaporation, the films were grown at pyrometer temperature 745 °C with a wafer rotation speed of 1000 rpm. Growth rates were determined by fitting energy-dispersive X-ray spectroscopy spectra to film thicknesses using NIST DTSA-II software. The thickness estimates determined by this method were consistent with scanning transmission electron microscopy measurements done for selected samples. Scanning electron microscopy images revealed faceted surfaces indicative of a tendency toward three-dimensional growth. X-ray diffraction spectra confirmed that the films were highly crystalline and exhibited preferential orientation in alignment with the substrate. Atomic force microscopy measurements show that film thicknesses are consistent across samples grown on both GaN templates and sapphire substrates, with typical roughnesses around 10 nm. Transmittance spectra of films grown on double-side-polished sapphire substrates yielded band gaps of 4.28 +- 0.06 eV for samples exhibiting close-to-ideal stoichiometry. Comparison of the measured spectra with ab initio calculations are in good agreement both near the band gap and at higher energies where excitation is into higher-lying bands. These findings provide insight into the growth and characterization of MgGeN2, contributing to the development of this material for potential applications in optoelectronics and power electronics.
Materials Science (cond-mat.mtrl-sci)
submitted to APL Materials
Berezinskii-Kosterlitz-Thouless Renormalization Group Flow at a Quantum Phase Transition
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-27 20:00 EST
Matthias Thamm, Harini Radhakrishnan, Hatem Barghathi, C. M. Herdman, Arpan Biswas, Bernd Rosenow, Adrian Del Maestro
We present a controlled numerical study of the Berezinskii-Kosterlitz-Thouless (BKT) transition in the one-dimensional Bose-Hubbard model at unit filling, providing evidence of the characteristic logarithmic finite-size scaling of the BKT transition. Employing density matrix renormalization group and quantum Monte Carlo simulations under periodic boundary conditions, together with a systematic finite-size scaling analysis of bipartite particle number fluctuations, we resolve boundary-induced complications that previously obscured critical scaling. We demonstrate that a suitably chosen central region under open boundaries reproduces universal RG signatures, reconciling earlier discrepancies. Finally, leveraging a non-parametric Bayesian analysis, we determine the critical interaction strength with high precision, establishing a benchmark for BKT physics in one-dimensional quantum models.
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 8 figures
Theory of interaction-induced charge order in CrSBr
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Zhi-Hao Cui, Andrew J. Millis, David R. Reichman
CrSBr is a layered van der Waals insulator with a quasi one-dimensional electronic structure and in-plane ferromagnetic order. Recent experimental work on Li-doped CrSBr reveals quasi-1D charge modulated states. In this study, we develop ab initio effective models for CrSBr to investigate these states and solve them using mean-field theory and density matrix embedding theory. The models are parametrized using density functional theory, the constrained random phase approximation, and the Rytova-Keldysh form of the long-range Coulomb interaction. Our simulations indicate the emergence of a charge density wave state characterized by cosine-like intra-chain density modulations and inter-chain phase shifts that minimize the Coulomb repulsion. Notably, at a doping level corresponding to \(1/n\) electron per CrSBr unit, the most stable pattern exhibits a periodicity of \(n\) cells, in agreement with experimental observations and Peierls' instability arguments. Moreover, we demonstrate that the inter-chain order is sensitive to the range of Coulomb interactions. If the interaction is hard-truncated to a short-ranged form, some localized stripe-like states are computationally favored. This work provides an ab initio framework for understanding the interplay of competing electronic and magnetic phases in CrSBr and related materials.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Chemical Physics (physics.chem-ph)
10 Pages, 8 figures
Nonlinear contractile response of actomyosin active gels to control signals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
James Clarke (1), Francis Cavanna (1), Aniket Marne (1), Anthony Davolio (1), José Alvardo (1) ((1) Center for Nonlinear Dynamics, Department of Physics, The University of Texas at Austin, Austin, TX, USA)
Biological systems tightly regulate their physiological state using control signals. This includes the actomyosin cytoskeleton, a contractile active gel that consumes chemical free energy to drive many examples of cellular mechanical behavior. Upstream regulatory pathways activate or inhibit actomyosin activity. However, the contractile response of the actomyosin cytoskeleton to control signals remains poorly characterized. Here we employ reconstituted actomyosin active gels and subject them to step and pulsatile activation inputs. We find evidence for a nonlinear impulse response, which we quantify via a transfer function \(\delta \varepsilon / \delta g\) that relates input free-energy pulses \(\delta g\) to output strain pulses \(\delta \varepsilon\). We find a scaling relation \(\delta \varepsilon / \delta g \sim g^{-0.3}\). The negative sign of the exponent represents a decreased effectiveness of a contracting gel in converting energy to strain. We ascribe nonlinearity in our system to a density-dependent mechanism, which contrasts strain-stiffening nonlinear responses to external stresses. Contractile response to control signals is an essential step toward understanding how information from mechanical signaling processes flow through actomyosin networks in living, and likely also synthetic, cells.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Main text - 24 pages (with references), 3 Figures; Supplemental Material - 17 pages (with references), 1 Figure
Generalized diffusion process with nonlocal interactions: Continuous time random walk model and stochastic resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-27 20:00 EST
Pece Trajanovski, Irina Petreska, Katarzyna Gorska, Ljupco Kocarev, Trifce Sandev
A space fractional diffusion-like equation is introduced, which embodies the nonlocality in time, represented by the memory kernel and the non-locality in space. A specific example of the nonlocal term is considered in combination with three different forms of the memory kernel. To analyse the probability density function, we utilize the subordination approach. Subsequently, the corresponding continuous time random walk model is presented. Furthermore, we investigate the effects of the stochastic resetting on the dynamics of the process and we showed that in the long time limit the system approaches a nonequilibrium stationary state.
Statistical Mechanics (cond-mat.stat-mech)
Growth and characterization of single crystal cubic TaN and hexagonal Ta\(_2\)N films on c-plane Sapphire
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-27 20:00 EST
Anand Ithepalli, Amit Rohan Rajapurohita, Arjan Singh, Rishabh Singh, John Wright, Farhan Rana, Valla Fatemi, Huili (Grace)Xing, Debdeep Jena
Two single crystal phases of tantalum nitride were stabilized on c-plane sapphire using molecular beam epitaxy. The phases were identified to be \(\delta\)-TaN with a rocksalt cubic structure and \(\gamma\)-Ta\(_2\)N with a hexagonal structure. Atomic force microscopy scans revealed smooth surfaces for both the films with root mean square roughnesses less than 0.3 nm. Phase-purity of these films was determined by x-ray diffraction. Raman spectrum of the phase-pure \(\delta\)-TaN and \(\gamma\)-Ta\(_2\)N obtained will serve as a future reference to determine phase-purity of tantalum nitride films. Further, the room-temperature and low-temperature electronic transport measurements indicated that both of these phases are metallic at room temperature with resistivities of 586.2 \(\mu\Omega\)-cm for the 30 nm \(\delta\)-TaN film and 75.5 \(\mu\Omega\)-cm for the 38 nm \(\gamma\)-Ta\(_2\)N film and become superconducting below 3.6 K and 0.48 K respectively. The superconducting transition temperature reduces with applied magnetic field as expected. Ginzburg-Landau fitting revealed a 0 K critical magnetic field and coherence length of 18 T and 4.2 nm for the 30 nm \(\delta\)-TaN film and 96 mT and 59 nm for the 38 nm \(\gamma\)-Ta\(_2\)N film. These tantalum nitride films are of high interest for superconducting resonators and qubits.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Colossal magnetoresistance in a quasi-two-dimensional cluster glass semiconductor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Suman Kalyan Pradhan, Weiqi Liu, Jicheng Wang, Yongli Yu, Wenxing Chen, Jinbo Yang, Yanglong Hou, Rui Wu
With a surge of interest in spintronics, the manipulation and detection of colossal magnetoresistance in quasi-two-dimensional layered magnetic materials have become a key focus, driven by their relatively scarce occurrence compared to giant magnetoresistance and tunneling magnetoresistance. This study presents an investigation into the desired colossal magnetoresistance, achieved by introducing magnetic frustration through Te doping in quasi-two-dimensional antiferromagnet Cr2Se3 matrix. The resulting Cr0.98SeTe0.27 exhibits cluster glass-like behavior with a freezing temperature of 28 K. Magnetotransport studies reveal a significant negative magnetoresistance of up to 32%. Additionally, angle-dependent transport measurements demonstrate a magnetic field-induced transition from positive to negative resistance anisotropy, suggesting a magnetic field-driven alteration in the electronic structure of this narrow band gap semiconductor, a characteristic feature of the colossal magnetoresistance effect. This behavior is further corroborated by density functional theory calculations. This systematic investigation provides a crucial understanding of the control of colossal magnetoresistance in quasi-two-dimensional materials via competing exchange interactions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Critical scaling behavior in skyrmion host ferromagnet CrTe1.38
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Suman Kalyan Pradhan, Tuhin Debnath, Rui Wu
Materials hosting diverse topological spin textures hold significant potential for spintronic applications. In this context, CrTe1.38, a quasi-two-dimensional material, stands out due to its stable N'eel-type skyrmion phase over a wide temperature range, both with and without an applied magnetic field [APL 125, 152402 (2024)]. Thus, it is a promising candidate for investigating complex magnetic phenomena, offering valuable insights into the underlying magnetic interactions. This study investigates the critical behavior of CrTe1.38 near TC by measuring DC magnetic isotherms. A systematic analysis of these isotherms with the magnetic field applied along the easy axis allows us to determine the asymptotic critical exponents: beta = 0.314, gamma = 1.069, and delta = 4.556, where the Widom scaling law and scaling equations are verified the self-consistency and reliability. In this system, the magnetic exchange coupling J(r) is the long-range type and decays spatially at a rate slower than approximately 4.651. Most notably, a series of vertical lines in the low-field region of the initial magnetization curves below TC supports the existence of a skyrmion phase in this compound
Materials Science (cond-mat.mtrl-sci)
Robust Prediction of Frictional Contact Network in Near-Jamming Suspensions Employing Deep Graph Neural Networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Armin Aminimajd, Joao Maia, Abhinendra Singh
The viscosity of the suspension consisting of fine particles dispersed in a Newtonian liquid diverges close to the jamming packing fraction. The contact microstructure in suspensions governs this macroscopic behavior in the vicinity of jamming through a frictional contact network (FCN). FCN is composed of mechanical load-bearing contacts that lead to the emergence of rigidity near the jamming transition. The stress transmission and network topology, in turn, depend sensitively on constraints on the relative motion of the particles. Despite their significance, predicting the FCN, especially close to jamming conditions, remains challenging due to experimental and computational impediments. This study introduces a cost-effective machine learning approach to predict the FCN using a graph neural network (GNN), which inherently captures hidden features and underlying patterns in dense suspension by mapping interparticle interactions. Employing a variation of GNN called the Deep Graph Convolutional Network (DeepGCN) trained on data-driven simulations, this study demonstrates robust generalization and extrapolation capabilities, accurately predicting FCNs in systems with divergent flow parameters and phase spaces, despite each being trained exclusively on a single condition. The study covers a wide range of phase space, from semi-dilute to jammed states, spanning transient to steady states, while systematically varying parameters such as shear stress (\({\sigma}_{xy}\)), packing fraction(\({\phi}\)) and sliding and rolling friction (\({ {\mu}_s, {\mu}_r}\)). The results of this research pave the way for innovative transferable techniques in predicting the properties of particulate systems, offering new avenues for advancement in material science and related fields.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Fluid Dynamics (physics.flu-dyn)
Revisiting MnSe : a Magnetic Semiconductor with Spin-Phonon coupling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Suman Kalyan Pradhan, Arnab Bera, Soham Das, Yongli Yu, Jicheng Wang, Rui Wu
Spin-phonon interactions in 2D magnetic materials are crucial in advancing next-generation spintronic devices. Therefore, identifying new materials with significant spin-phonon interactions is of great importance. In this context, MnSe, previously recognized as an exemplary non-layered p-type semiconductor emerges in this study as an intriguing material with notable spin-phonon characteristics. The complex magnetism in pristine MnSe, primarily dominated by antiferromagnetism with a weak ferromagnetic component, gives rise to both spontaneous and conventional exchange bias effects at low temperatures. In an effort to understand this intriguing magnetism, we conducted a detailed Raman spectroscopy study, which reveals unconventional deviations from the usual phonon anharmonicity around Neel temperature (170 K), in the self-energies of the P1, P2, and P3 modes. Notably, the P1 mode is most sensitive to spin-phonon coupling, while the P2 mode is particularly responsive to the structural phase transition at 250 K. Therefore, these findings provide comprehensive insights into the phase transitions of pristine MnSe, particularly highlighting the previously unobserved interplay between its magnetic behavior and phonon dynamics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Observation of Topological Nodal-Ring Phonons in Monolayer Hexagonal Boron Nitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Zhiyu Tao, Yani Wang, Shuyi He, Jiade Li, Siwei Xue, Zhibin Su, Jiatao Sun, Hailin Peng, Jiandong Guo, Xuetao Zhu
Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems, particularly phononic excitations in crystalline materials. Two-dimensional (2D) topological phonons emerge as promising candidates for future technological applications. Currently, experimental verification of 2D topological phonons has remained exclusively limited to graphene, a constraint that hinders their applications in phononic devices. Here, we report experimental evidence of topological phonons in monolayer hexagonal boron nitride using advanced high-resolution electron energy loss spectroscopy. Our high-precision measurements explicitly demonstrate two topological nodal rings in monolayer hexagonal boron nitride, protected by mirror symmetry, expanding the paradigm of 2D topological phonons beyond graphene. This research not only deepens fundamental understanding of 2D topological phonons, but also establishes a phononic device platform based on wide-bandgap insulators, crucial for advancements in electronics and photonics applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 4 figures
Chinese Physics Letters 42 027405 (2025)
Pseudo-Hermitian physics from dynamically coupled macrospins
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Peter Connick, Shane P. Kelly, Yaroslav Tserkovnyak
We consider two classical macrospins with dynamical (frequency-dependent) coupling, modeled by a generalized Landau-Lifshitz-Gilbert equation. We show that, in the absence of local damping, the resulting dynamics are pseudo-Hermitian. When two precessional modes hybridize near a crossing, the spectral behavior takes the form either of an anticrossing or level attraction, with the latter formalized in terms of spontaneous \(\mathcal{PT}\)-symmetry breaking. Near equilibrium, mixing due to nondissipative interactions results in repulsion, while dissipative mixing results in attraction. In contrast, when the fluctuating degrees of freedom form a free-energy saddle point, we find that nondissipative interactions result in level attraction, while dissipative interactions produce level repulsion. Accounting for the effects of local Gilbert damping, we examine the cases in which approximate \(\mathcal{PT}\)-symmetry breaking is still possible and determine the degree to which the qualitative spectral properties still persist.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 3 figures, 2 tables
High-Velocity Magnetic Domain Wall Motion Driven by Out-of-Plane Acoustic Spin
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-27 20:00 EST
Jiacheng Lu, Fa Chen, Yiming Shu, Yukang Wen, Hang Zou, Yuhao Liu, Xiaofei Yang, Shiheng Liang, Wei Luo, Yue Zhang
We predict high-velocity magnetic domain wall (DW) motion driven by out-of-plane acoustic spin in surface acoustic waves (SAWs). We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128 degree Y-LiNbO3 substrate exhibits uniform spin angular momentum, which induces the DW motion at a velocity exceeding 50 m/s, significantly faster than previous DW motions at about 1 m/s velocity driven by conventional SAWs. This remarkable phenomenon highlights the potential of acoustic spin in enabling rapid DW displacement, offering an innovative approach to developing energy-efficient spintronic devices.
Other Condensed Matter (cond-mat.other)
Stochastic Gross-Pitaevskii theory for a spin-1 Bose gas: Application to superfluidity in two dimensions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-27 20:00 EST
Andrew P. C. Underwood, P. B. Blakie
This paper develops and implements the stochastic projected Gross-Pitaevskii equation for spin-1 Bose gases, addressing key considerations for numerical simulations. As an application of the theory we explore equilibrium phases in a two-dimensional spin-1 gas, where quasi-long-range order emerges via a Berezinskii-Kosterlitz-Thouless transition. Our analysis includes definition of superfluid densities for both mass and spin degrees of freedom, in a manner suitable for implementation within a stochastic projected Gross-Pitaevskii equation simulation. We present a finite-temperature phase diagram for the ferromagnetic spin-1 Bose gas and identify three distinct superfluid phases: two exhibiting conventional Berezinskii-Kosterlitz-Thouless-like behavior and a novel phase that simultaneously supports independent mass and spin superflows. As temperature increases, the stability region of this novel phase shrinks. This work provides a foundation for further studies of nonequilibrium and finite-temperature phenomena in spinor Bose gases.
Quantum Gases (cond-mat.quant-gas)
13 pages, 5 figures
Pinch-point Singularities in Stress-Stress Correlations Reveal Rigidity in Colloidal Gels
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Albert Countryman, H. A. Vinutha, Fabiola Diaz Ruiz, Xiaoming Mao, Emanuela Del Gado, Bulbul Chakraborty
We demonstrate that the spatial correlations of microscopic stresses in 2D model colloidal gels obtained in computer simulations can be quantitatively described by the predictions of a theory for emergent elasticity of pre-stressed solids (vector charge theory). By combining a rigidity analysis with the characterization provided by the stress correlations, we show that the theoretical predictions are able to distinguish rigid from floppy gels, and quantify that distinction in terms of the size of a pinch-point singularity emerging at large length scales, which, in the theory, directly derives from the constraints imposed by mechanical equilibrium on the internal forces. We also use the theoretical predictions to investigate the coupling between stress-transmission and rigidity, and we explore the possibility of a Debye-like screening mechanism that would modify the theory predictions below a characteristic length scale.
Soft Condensed Matter (cond-mat.soft)
9 pages, 5 figures
Phonon dynamics of a bulk WSe\(_2\) crystal excited by ultrashort near-infrared pulses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Itsuki Kasai, Itsuki Takagi, Kazutaka G. Nakamura
Pump-probe reflectivity measurements have been performed on a single crystal of tungsten diselenide (WSe\(_2\)) using ultrashort near-infrared pulses. The behavior is well reproduced in simulations superimposing three oscillations (7.45, 7.49 and 7.7 THz) with different phases. The Fourier transform spectrum features small peaks at 4.0 and 11.5 THz along with intense peaks at around 7.5 THz.
Materials Science (cond-mat.mtrl-sci)
4 pages, 4 figures
Nested Shadows of Anyons:A Framework for Identifying Topological Phases
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-27 20:00 EST
The 1-form symmetries in two-dimensional topological systems are ``shadowed'' as global symmetries in their one-dimensional quantum transfer matrices. In this work, we introduce a distinct shadow effect arising from the pair-creation of anyons, which manifests as a local symmetry of the quantum transfer matrix. The interplay between these two shadow effects provides a powerful framework for characterizing topological phases without extensive numerical simulations. Specifically, we derive the phase diagram of the filtered toric code state and precisely identify phase boundaries using the nested shadows of anyons. Additionally, we reveal that a class of topological states host gapless edge modes protected by 1-form symmetry rather than global symmetry. Finally, we apply our approach to the three-dimensional toric code and X-cube states, uncovering a nontrivial path in phase space that connects them through a subdimensional critical point, which is highly challenging to detect numerically due to the complexity of simulating three-dimensional systems.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 6 figures, supplementary materials
Symmetry breaking of large-amplitude parametric oscillations in a few-layer graphene nanomechanical resonator
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Chen Yang, YuBin Zhang, Heng Lu, Ce Zhang, FengNan Chen, Ying Yan, Fei Xue, Alexander Eichler, Joel Moser
Graphene nanomechanical resonators are well suited for the study of parametric oscillations. Their large frequency tunability and their pronounced nonlinearities enable an efficient modulation of their resonant frequency. Here, we present measurements of the response of a few-layer graphene nanomechanical resonator driven by a large parametric pump at frequency \(2\omega\) and a weak external drive at \(\omega\), where \(\omega\) is set near the mechanical resonant frequency \(\omega_0\). The pump actuates the resonator beyond the threshold for large-amplitude parametric oscillations, while the drive breaks the symmetry of the parametric phase states. By increasing and decreasing a gate voltage to detune \(\omega_0\) in the presence of the pump and the drive, we observe a double hysteresis in the response. The double hysteresis reveals the existence of two possible large-amplitude vibrational states whose phase difference is nearly \(\pi\) radians. We deterministically prepare the resonator in either one of these states by cycling the gate voltage. We measure the stationary occupation probabilities of the two states in the presence of a white Gaussian force noise, and find that they strongly depend on the amplitude and on the phase of the external drive. Parametric oscillations with broken phase symmetry hold promise as units of binary information. Their phase states can be mapped to biased bi-modal degrees of freedom, such as Ising spins in an external magnetic field. Our work invites future studies on coupled graphene parametric resonators whose phase states may be mapped to a system of Ising spins.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Bridging Spectroscopy and Advanced Molecular Orientation Analysis with New 4+ Angle Polarization Toolbox in Quasar
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Callum Gassner, Jitraporn Vongsvivut, Meguya Ryu, Soon Hock Ng, Marko Toplak, Vijayakumar Anand, Pooja Takkalkar, Mary Louise Fac, Natalie A. Sims, Bayden R. Wood, Mark J. Tobin, Saulius Juodkazis, Junko Morikawa
Anisotropy plays a critical role in governing the mechanical, thermal, electrical, magnetic, and optical properties of materials, influencing their behavior across diverse applications. Probing and quantifying this directional dependence is crucial for advancing materials science and biomedical research, as it provides a deeper understanding of structural orientations at the molecular level, encompassing both scientific and industrial benefits. This study introduces the "4+ Angle Polarization" widget, an innovative extension to the open-source Quasar platform (this https URL), tailored for advanced multiple-angle polarization analysis. This toolbox enables precise molecular orientation analysis of complex microspectroscopic datasets through a streamlined workflow. Using polarized Fourier transform infrared (p-FTIR) spectroscopy, we demonstrate its versatility across various sample types, including polylactic acid (PLA) organic crystals, murine cortical bone, and human osteons. By overcoming the limitations of traditional two-angle methods, the widget significantly enhances the accuracy of structural and orientational analysis. This novel analytical tool expands the potential of multiple-angle p-FTIR techniques into advanced characterization of structural anisotropy in heterogeneous systems, providing transformative insights for materials characterization, biomedical imaging and beyond.
Materials Science (cond-mat.mtrl-sci), Biological Physics (physics.bio-ph), Medical Physics (physics.med-ph)
20 pages, 9 figures
Gate-Voltage-Driven Quantum Phase Transition at \(0.7 (2e^2/h)\) in Quantum Point Contacts
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
The complex gate-voltage-dependent differential conductance in quantum point contacts, shaped by entangled-state tunneling, was demonstrated through the movement of a localized spin. This spin responds to variations in side gate voltage, triggering a quantum phase transition (QPT) between symmetric and asymmetric Kondo coupling states, with the states separated by conductance regions \(G \geq 0.7 G_0\) and \(G \leq 0.7 G_0\), where \(G_0 = 2e^2/h\), respectively. The asymmetric state has two Kondo temperatures, while the symmetric state has only one. The presence of two Kondo temperatures in the asymmetric state clarifies previously unresolved issues, such as the indeterminate Kondo temperature and anomalous behavior in the width of the zero-bias anomaly (ZBA) in the \(G \leq 0.7 G_0\) region. The QPT was investigated by analyzing the gate-voltage-dependent ZBA energy, calculated using the corresponding local density of states at the site of the localized spin, obtained during the replication of the differential conductance.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 6 figures
Machine Learning a Phosphor's Excitation Band Position
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Nakyung Lee, Małgorzata Sójka, Annie La, Syna Sharma, Seán Kavanagh, Docheon Ahn, David O. Scanlon, Jakoah Brgoch
Creating superior lanthanide-activated inorganic phosphors is pivotal for advancing energy-efficient LED lighting and backlit flat panel displays. The most fundamental property these luminescent materials must possess is effective absorption/excitation by a blue InGaN LED for practical conversion into white light. The 5\(d_1\) excited state energy level of lanthanides, which determines the excitation peak position, is influenced by the inorganic host structure, including the local environment, crystal structure, and composition, making it challenging to predict in advance. This study introduces a new extreme gradient boosting machine learning method that quantitatively determines a phosphor's longest (lowest energy) excitation wavelength. We focus on the Ce\(^{3+}\) 4\(f\) \(\rightarrow\) 5\(d\) transition due to its well-defined 5\(d_1\) energy level observed in excitation and diffuse reflectance spectra. The model was trained on experimental data for 357 Ce\(^{3+}\) cation substitution sites sourced from literature and in-house measurements and ultimately experimentally validated through the successful synthesis of a novel, blue-excited, green-emitting phosphor: Ca\(_2\)SrSc\(_6\)O\(_{12}\):Ce\(^{3+}\). This compound's excitation under commercial blue LED wavelength aligned remarkably well with the model's predictions. These results highlight the transformative potential of data-driven approaches in expediting the discovery of blue-absorbing phosphors for next-generation LED lighting.
Materials Science (cond-mat.mtrl-sci)
Engineering MoS2-MoTe2 Heterojunctions: Enhancing Piezoresponse and Rectification
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Sai Saraswathi Yarajena, Akshay K. Naik
Piezoelectric materials play a vital role in energy harvesting, piezotronics and various self-powered sensing applications. The piezoelectric strength of 2D materials is limited by the carrier charge screening, leading to reduced open circuit voltages and poor piezotronic performances. Reducing the carrier screening in devices is a key requirement to fully utilize the potential of 2D materials for piezoelectric applications. In this work, we demonstrate that lateral heterojunction devices offer an excellent way to improve the piezoelectric open circuit voltages and rectification ratios. Because of the asymmetric contacts with Nickel (Ni) electrodes, the heterojunctions of monolayer(1L) MoS_2 and MoTe_2 form a hybrid Schottky/p-n diode. We demonstrate a rectification ratio of more than 5000 without electrostatic gating. We observed that devices with higher junction potentials exhibit piezoelectric open-circuit voltages exceeding 1V and a peak power density of 690 mW/m^2. The output characteristics reveal a trade-off between open circuit voltages and rectification ratios. These findings and the role of built-in (cut-in) voltages in energy harvesting provide valuable insights for the design of piezotronic junctions to achieve high piezoelectric output and/or rectification ratios. Design aspects of heterojunctions discussed in this manuscript can be applied to other emerging nanomaterials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Exchange Coupling Modulation in MN4-Embedded Graphene Layers (M=Mn, Fe, Co, Cu) Under Strain
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Mahnaz Rezaei, Jahanfar Abouie, Fariba Nazari
MN4-embedded graphene (MN4-G) layers, with transition metal elements M, are experimentally accessible two-dimensional (2D) materials and show great potential for stable nanoscale magnetization. In these materials, the exchange couplings between magnetic atoms are predominantly governed by Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, exhibiting an unusual prolonged decay of r to the power of minus n, where r is the M-M separation distance, and n is between 0.5 and 2. In this paper, we explore the effects of induced strain on the electronic and magnetic properties of MN4-G layers through ab-initio density functional theory. We employ a specific method to apply strain by positioning atoms from one layer within the equilibrium structure of another layer, thereby inducing strain in the form of either tension or compression. The induced strain results in an approximate plus/minus 0.4% variation in the unit-cell area of the MN4-G lattice. Our findings reveal that while the exchange coupling mechanism remains unaffected, the strength, amplitude, and decay rate of the RKKY coupling are significantly influenced by the induced strain. Notably, the CoN4-G layer exhibits a remarkable increase in the strength and oscillation amplitude of the RKKY coupling, along with a reduced decay rate. Additionally, the electronic and magnetic properties of the CuN4-G layers remain unchanged under induced strain.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
40 pages, 12 figures, 3 tables
Experimental Observation of Topological Disclination States in Lossy Electric Circuits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Jin Liu, Wei-Wu Jin, Zhao-Fan Cai, Xin Wang, Yu-Ran Zhang, Xiaomin Wei, Wenbo Ju, Zhongmin Yang, Tao Liu
Topological phase transitions can be remarkably induced purely by manipulating gain and loss mechanisms, offering a novel approach to engineering topological properties. Recent theoretical studies have revealed gain-loss-induced topological disclination states, along with the associated fractional charge trapped at the disclination sites. Here, we present the experimental demonstration of topological disclination states in a purely lossy electric circuit. By designing alternating lossy electric circuit networks that correspond to the disclination lattice, we observe a voltage response localized at the disclination sites and demonstrate the robustness of these states against disorder. Furthermore, we measure the charge distribution, confirming the presence of fractional charge at the disclination sites, which gives rise to the topological disclination states. Our experiment provides direct evidence of gain-loss-induced topological disclination states in electric circuits, opening new possibilities for applications in classical systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Unveiling Crystalline Order from Glassy Behavior of Charged Rods at Very Low Salt Concentrations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Hanna Anop, Laura Dal Compare, Frederic Nallet, Achille Giacometti, Eric Grelet
Charged colloids can form ordered structures like Wigner crystals or glasses at very low concentrations due to long-range electrostatic repulsions. Here, we combine small-angle x-ray scattering (SAXS) and optical experiments with simulations to investigate the phase behavior of charged rodlike colloids across a wide range of salt concentrations and packing fractions. At ultra low ionic strength and packing fractions, we reveal both experimentally and numerically a direct transition from a nematic to a crystalline smectic-B phase, previously identified as a glass state. This transition, bypassing the smectic-A intermediate phase, results from minimizing Coulomb repulsion and maximizing entropic gains due to fluctuations in the crystalline structure. This demonstrates how long-range electrostatic repulsion significantly alters the phase behavior of rod-shaped particles and highlights its key-role in driving the self-organization of anisotropic particles.
Soft Condensed Matter (cond-mat.soft)
To be published in Phys. Rev. Lett. (2025)
Reactive sputtering of SnS thin films using sulfur plasma and a metallic tin target: achieving stoichiometry and large grains
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Daiki Motai, Issei Suzuki, Taichi Nogami, Takahisa Omata
This study presents a novel method for fabricating stoichiometric SnS thin films with large grain sizes via reactive sputtering using a metallic Sn target and sulfur plasma (S-plasma). Unlike conventional approaches that rely on toxic H2S gas, this method employs a S-plasma to enhance sulfur reactivity and mitigate sulfur deficiencies during film deposition. By optimizing the balance between the sputtering conditions of the Sn target and the supply conditions of the S-plasma, dense single-phase SnS thin films with micron-scale grain sizes were achieved at a substrate temperature of 300 degree C, achieving an in-plane Hall mobility of 13 cm2 V-1 s-1. Furthermore, crystalline SnS thin films were fabricated even on a room-temperature substrate, enabling potential applications in flexible devices with heat-sensitive substrates. These findings demonstrate the effectiveness of S-plasma in advancing SnS thin film fabrication, providing a safer and more efficient route to high-performance photovoltaic materials.
Materials Science (cond-mat.mtrl-sci)
20 pages, 9 figures, 1 table
Antiferromagnetic resonance in \(α\)-MnTe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
J. Dzian, P. Kubaščík, S. Tázlarů, M. Białek, M. Šindler, F. Le Mardelé, C. Kadlec, F. Kadlec, M. Gryglas-Borysiewicz, K. P. Kluczyk, A. Mycielski, P. Skupiński, J. Hejtmánek, R. Tesař, J. Železný, A.-L. Barra, C. Faugeras, J. Volný, K. Uhlířová, L. Nádvorník, M. Veis, K. Výborný, M. Orlita
Antiferromagnetic resonance in a bulk \(\alpha\)-MnTe crystal is investigated using both frequency-domain and time-domain THz spectroscopy techniques. At low temperatures, an excitation at the photon energy of 3.5 meV is observed and identified as a magnon mode through its distinctive dependence on temperature and magnetic field. This behavior is reproduced using a simplified model for antiferromagnetic resonance in an easy-plane antiferromagnet, enabling the extraction of the out-of-plane component of the single-ion magnetic anisotropy reaching (40 \(\pm\) 10) \(\mu\)eV.
Materials Science (cond-mat.mtrl-sci)
12 pages, 7 figures
Chiral anomaly in the Weyl semimetal TaRhTe\(_4\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-27 20:00 EST
M. Behanmi (1,2,3), D. V. Efremov (1), S. Aswartham (1), G. Shipunov (1), B. R. Piening (1), C. G. F. Blum (1), V. Kocsis (1), J. Dufouleur (1), I. Pallecchi (4), M. Putti (3,4), B. Büchner (1,2), H. Reichlova (1,2,5), F. Caglieris (4) ((1) IFW Dresden, Germany, (2) Institut für Festkörper und Materialphysik, Technische Universität Dresden, Germany, (3) Department of Physics, University of Genoa, Italy, (4) CNR-SPIN, Italy, (5) Institute of Physics ASCR, Czech Republic)
TaRhTe\(_4\) is a type-IIWeyl semimetal, exhibiting fourWeyl points in proximity to the Fermi level. In this article, we report our results of a systematic study of longitudinal magnetoresistance in TaRhTe\(_4\). Our findings indicate that magnetoresistance becomes negative only when the magnetic field is applied parallel to the electric field. By rotating E (as well as B), we show that its origin is consistent with the prediction of the chiral anomaly, while the current jetting effect and weak localization could be excluded. The negative magnetoresistance persists up to room temperature, suggesting that TaRhTe4 exhibits distinctive properties within the family of Weyl semimetals.
Strongly Correlated Electrons (cond-mat.str-el)
Influence of Chemistry and Topography on the Wettability of Copper
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Sarah Marie Lößlein, Rolf Merz, Yerila Rodríguez-Martínez (IJL), Florian Schäfer, Philipp Grützmacher, David Horwat (IJL), Michael Kopnarski, Frank Mücklich
To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality. We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D). Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces' wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on the peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing the aspect ratio showed to enhance air-inclusions and hydrophobicity despite increased peak roughness while time dependent wetting transitions were observed.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Journal of Colloid and Interface Science, 2024, 670, pp.658-675
High-Pressure Tuning of Electrical Transport in Freestanding Oxide Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Jingxin Chen, Xiang Huang, Zhihan Qiao, Jiao Li, Jiahao Xu, Haiyang Zhang, Deyang Li, Enyang Men, Hangtian Wang, Han Zhang, Jianyu Xie, Guolin Zheng, Mingliang Tian, Qun Niu, Lin Hao
Electrical transport of oxide films under high pressure is largely unexplored due to the absence of a universal strategy. In this work, we have developed an in-house route to investigate the electrical transport properties of oxide films under high pressures, by improving the elasticity of freestanding oxide films and the robustness of high-pressure techniques on nano-devices. As a showcase, we investigated the electrical resistivity of perovskite SrIrO3 films under high pressures, and found a pressure-driven semimetal-to-insulator transition and an insulator-to-metal transition. At the monolayer-limit, the SrIrO3 films directly transform from an insulating state to a metallic state, highlighting the intriguing interplay of dimensionality and hydrostatic pressure in correlated oxides, which can be unveiled through the universal high-pressure strategy.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Unlocking Hidden Potential in Electron Holography of Non-Collinear Spin Textures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Moritz Winterott, Samir Lounis
Due to their particle-like properties, three-dimensional (3D) spin textures have garnered significant interest, particularly for their potential applications in next-generation information storage devices. However, efficiently identifying these textures remains a major challenge. Here, we approach this problem from a new perspective. Rather than relying solely on the magnetic stray field, which vanishes in antiferromagnets, we use multiple-scattering theory to demonstrate that spin textures carry nontrivial charges due to the noncollinearity of magnetic moments. This induced charge encodes magnetic information driven by spin-mixing and spin-orbit interactions. We propose leveraging electron holography to extract this information by reconstructing phase images obtained from transmission electron microscopy (TEM). To quantify this effect, we systematically calculate and compare the contributions of both conventional and newly identified mechanisms to the phase images, considering different electronic structure parameters. Our findings mark a significant milestone in advancing the exploration and possible application of 3D spin textures in next-generation spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
The Rise of Refractory Transition-Metal Nitride Films for Advanced Electronics and Plasmonics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Jiachang Bi, Ruyi Zhang, Xiong Yao, Yanwei Cao
The advancement of semiconductor materials has played a crucial role in the development of electronic and optical devices. However, scaling down semiconductor devices to the nanoscale has imposed limitations on device properties due to quantum effects. Hence, the search for successor materials has become a central focus in the fields of materials science and physics. Transition-metal nitrides (TMNs) are extraordinary materials known for their outstanding stability, biocompatibility, and ability to integrate with semiconductors. Over the past few decades, TMNs have been extensively employed in various fields. However, the synthesis of single-crystal TMNs has long been challenging, hindering the advancement of their high-performance electronics and plasmonics. Fortunately, progress in film deposition techniques has enabled the successful epitaxial growth of high-quality TMN films. In comparison to reported reviews, there is a scarcity of reviews on epitaxial TMN films from the perspective of materials physics and condensed matter physics, particularly at the atomic level. Therefore, this review aims to provide a brief summary of recent progress in epitaxial growth at atomic precision, emergent physical properties (superconductivity, magnetism, ferroelectricity, and plasmon), and advanced electronic and plasmonic devices associated with epitaxial TMN films.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
27 pages, 9 figures
Advanced Materials Interfaces 2025
Emergent fractals in hBN-encapsulated graphene based supermoiré structures and their experimental signatures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Deepanshu Aggarwal, Rohit Narula, Sankalpa Ghosh
Supermoiré structures (SMS), formed by overlapping moiré-patterns in van der Waals heterostructures, display complex behaviour that lacks a comprehensive low-energy theoretical description. We demonstrate that these structures can form emergent fractals under specific conditions and identify the parameter space where this occurs in hexagonal trilateral SMS. This fractality enables a reliable calculation of low-energy band counts, which are crucial for understanding both single-particle and correlation effects. Using an effective Hamiltonian that includes in- and out-of-plane lattice relaxation, we analyze SMS in hBN-encapsulated single and bilayer graphene. We prescribe methods to experimentally verify these fractals and extract their fractal dimension through angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM).
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 latexed pages, 4 Figures, supplementary .pdf file is available in the same url
Stronger femtosecond excitation causes slower electron-phonon coupling in silicon
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
A. B. Swain, J. Kuttruff, J. Vorberger, P. Baum
Electron-hole pairs in semiconductors are essential for solar cells and fast electronic circuitry, but the competition between carrier transport and relaxation into heat limits the efficiency and speed. Here we use ultrafast electron diffraction with terahertz pulse compression to measure the electron-phonon decay rate in single-crystal silicon as a function of laser excitation strength. We find that the excited electrons relax slower into phonons for higher carrier densities. The electron-phonon scattering rate changes in a nonlinear way from 400 fs at ~\(2 \times 10^{20} \text{ cm}^{-3}\) to 1.2 ps at ~\(4 \times 10^{20} \text{ cm}^{-3}\). These results indicate that a hot electron gas quenches the scattering into phonons in a temperature-dependent way. Ultrafast electronic circuitry of silicon therefore should work faster and provide higher bandwidths at lower carrier densities.
Materials Science (cond-mat.mtrl-sci)
11 pages, 3 figures
Enhanced deep-freezing magneto- and elasto-caloric effects by modifying lattice anharmonicity and electronic structures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Xiao-Ming Huang, Ying Zhao, Xiaowen Hao, Hua-You Xiang, Jin-Han Yang, Chin-Wei Wang, Wenyun Yang, Cuiping Zhang, Binru Zhao, Jie Ma, Zongbin Li, Yafei Kuang, Liang Zuo, Xin Tong, Hai-Le Yan, Qingyong Ren
Designing the high performance magneto or elastocaloric effect in NiMnIn alloys with spin-lattice coupling in a deep freezing temperature range of 200 K to 255 K is challenging due to the limited lattice entropy change and large negative contribution of magnetic entropy change during phase transitions. In this work, we systematically study the first order magneto-structural transition in NiMnIn based alloys by in-situ microstructural characterizations, physical property measurements, and first principles calculations. A multi element alloying strategy involving Cu and Ga co doping is proposed to manipulate the phase transition. The co doping reduces the lattice anharmonicity and thermal expansion coefficient of the martensitic phase, leading to an increase in the unit cell volume change and lattice entropy change. It also modifies the electronic density of states, causing a decrease in the magnetization change .The relief of the lattice mismatch reduces hysteresis losses in the refrigeration cycle. These synergetic effects yield excellent magneto and elastocaloric effects,with the effective magnetocaloric refrigeration capacity reaching up to 182 J/kg under the magnetic field of 5 T or an adiabatic temperature change of -4 K under a low field of 1.5 T and the elastocaloric coefficient of performance to 30 or an adiabatic temperature change of -7 K with the strain of 5% at 230 K, offering a potential solution for solid-state deep-freezing refrigeration.
Materials Science (cond-mat.mtrl-sci)
A few-layer graphene nanomechanical resonator driven by digitally modulated video signals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Ce Zhang, Heng Lu, Chen Yang, YuBin Zhang, FengNan Chen, Ying Yan, Joel Moser
Nanomechanical resonators driven by multifrequency signals combine the physics of mesoscopic vibrations and the technologies of radio communication. Their simplest property stems from their resonant response: they behave as filters, responding only to driving signals whose frequency range is contained within that of the mechanical response. While the response is routinely probed with a single tone drive, a multifrequency drive offers the possibility of inducing richer vibrational dynamics. In this case, all the frequency components of the drive are simultaneously transduced into vibrations with different amplitudes and phases that superimpose and interfere. Here, we employ a few-layer graphene nanomechanical resonator as a filter for broadband, digitally modulated video signals. We transduce the modulated drive into modulated vibrations, which we demodulate into a nanomechanical video. Our work reveals distinctive features in vibrations driven by a coherent, multifrequency drive unseen in vibrations actuated by single tone drives or by a force noise.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Machine learning short-ranged many-body interactions in colloidal systems using descriptors based on Voronoi cells
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Rinske M. Alkemade, Rastko Sknepnek, Frank Smallenburg, Laura Filion
Machine learning (ML) strategies are opening the door to faster computer simulations, allowing us to simulate more realistic colloidal systems. Since the interactions in colloidal systems are often highly many-body, stemming from e.g. depletion and steric interactions, one of the challenges for these algorithms is capturing the many-body nature of these interactions. In this paper, we introduce a new ML-based strategy for fitting many-body interactions in colloidal systems where the many-body interaction is highly local. To this end, we develop Voronoi-based descriptors for capturing the local environment and fit the effective potential using a simple neural network. To test this algorithm, we consider a simple two-dimensional model for a colloid-polymer mixture, where the colloid-colloid interaction and colloid-polymer interactions are hard-disk like, while the polymers themselves interact as ideal gas particles. We find that a Voronoi-based description is sufficient to accurately capture the many-body nature of this system. Moreover, we find that the Pearson correlation function alone is insufficient to determine the predictive power of the network emphasizing the importance of additional metrics when assessing the quality of ML-based potentials.
Soft Condensed Matter (cond-mat.soft)
Deciphering competing interactions of Kitaev-Heisenberg-\(Γ\) system in clusters: part II -- dynamics of Majorana fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Sheikh Moonsun Pervez, Saptarshi Mandal
We perform a systematic and exact study of Majorana fermion dynamics in the Kitaev-Heisenberg-\(\Gamma\) model in a few finite-size clusters increasing in size up to twelve sites. We employ exact Jordan-Wigner transformations to evaluate certain measures of Majorana fermion correlation functions, which effectively capture matter and gauge Majorana fermion dynamics in different parameter regimes. An external magnetic field is shown to produce a profound effect on gauge fermion dynamics. Depending on certain non-zero choices of other non-Kitaev interactions, it can stabilise it to its non-interacting Kitaev limit. For all the parameter regimes, gauge fermions are seen to have slower dynamics, which could help build approximate decoupling schemes for appropriate mean-field theory. The probability of Majorana fermions returning to their original starting site shows that the Kitaev model in small clusters can be used as a test bed for the quantum speed limit.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 13 figures. The previous arXiv submission arXiv:2306.14839 has been divided into two parts. It is the part-II
2025 J. Phys.: Condens. Matter 37 025803
Efficient and Accurate Spatial Mixing of Machine Learned Interatomic Potentials for Materials Science
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Fraser Birks, Thomas D Swinburne, James R Kermode
Machine-learned interatomic potentials offer near first-principles accuracy but are computationally expensive, limiting their application in large-scale molecular dynamics simulations. Inspired by quantum mechanics/molecular mechanics methods, we present ML-MIX, an efficient and flexible LAMMPS package for accelerating simulations by spatially mixing interatomic potentials of different complexities. Through constrained linear fitting, we show it is possible to generate a 'cheap' approximate model which closely matches an 'expensive' reference in relevant regions of configuration space. We demonstrate the capability of ML-MIX through case-studies in Si, Fe, and W-He systems, achieving up to an 11x speedup on 8,000 atom systems without sacrificing accuracy on static and dynamic quantities, including calculation of minimum energy paths and dynamical simulations of defect diffusion. For larger domain sizes, we show that the achievable speedup of ML-MIX simulations is limited only by the relative speed of the cheap potential over the expensive potential. The ease of use and flexible nature of this method will extend the practical reach of MLIPs throughout computational materials science, enabling parsimonious application to large spatial and temporal domains.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
21 pages, 13 figures. To access the ML-MIX GitHub, click this https URL
Quantifying local heterogeneities in the 3D morphology of X-PVMPT battery electrodes based on FIB-SEM measurements
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
L. Dodell, M. Neumann, M. Osenberg, A. Hilger, G. Studer, B. Esser, I. Manke, V. Schmidt
Organic electrode-active materials (OAMs) not only enable a variety of charge and storage mechanisms, but are also safer for the environment and of lower cost compared to materials in commonly used lithium-ion batteries. Cross-linked Poly(3)-vinyl-N-methylphenothiazine (X-PVMPT) is a p-type OAM which shows high performance and enables fast and reversible energy storage in different battery configurations. The performance of an OAM does not only depend on its molecular or polymer structure, but also on the structure of the composite electrode. The porous nanostructure of an electrode composed of X-PVMPT, a conductive carbon additive and binder is investigated by statistical image analysis, based on 3D image data obtained by focused-ion beam scanning-electron microscopy (FIB-SEM) measurements. Univariate probability distributions of relevant morphological descriptors as well as bivariate distributions of pairs of such descriptors are parametrically modelled, among others, by utilization of copulas in the latter case. These models are then used for quantifying local heterogeneities of X-PVMPT considered in this paper. Furthermore, it is shown that the nanostructure changes when traversing from bottom to top face of the electrode, which influences its performance. While the observed short transportation paths trough the solid phase are beneficial in terms of electrical conductivity, the pathways through the pore phase influencing the effective ionic diffusivity are--in comparison--rather long.
Materials Science (cond-mat.mtrl-sci)
25 pages, 6 Figures
Topological Invariants in Invasion Percolation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-27 20:00 EST
Based on bond percolation theory, a method is presented here to calculate the relationship between capillary pressure and saturation in porous media from first principles. The governing equations are formulated on the undirected graph of the pore network. The graph is a simplified mathematical object that accounts for the topology of the pore structure. Thus, the calculation is extremely computationally efficient since it is mesh-free and voxel-free. Two topological invariants are identified: The bond percolation threshold and the residual saturation. Bond percolation theory is used to obtain a closed-form pressure-saturation relation in terms of the geometry of the pores (pore throat distribution) and material parameters (contact angle and interfacial tension), universal exponents, and topological invariants, based on scaling relations.
Statistical Mechanics (cond-mat.stat-mech)
5 pages, 4 figures
Magnetic anisotropy and magnetoelastic properties of Weyl magnetic semimetal Co2MnGa thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
O. Chumak, A. Nabiałek, L.T. Baczewski, T. Seki, J. Wang, K. Takanashi, H. Szymczak
The magnetic anisotropy and magnetoelastic properties of the magnetic Weyl semimetal Co2MnGa were investigated by exploiting the Co2MnGa thin films with different chemical orderings. The epitaxial layers were grown by sputtering directly on MgO (001) and the annealing temperatures after the deposition were varied, which allowed us to change the chemical ordering of Co2MnGa. We observed a clear relationship between the annealing temperature and the parameters of magnetic property. The most significant changes of both the magnetic anisotropy and the magnetoelastic properties were correlated with the appearance of the L21 ordered phase, suggesting that the emergence of magnetic Weyl semimetallic feature is the key point to vary these magnetic properties.
Materials Science (cond-mat.mtrl-sci)
7 pages, 3 figures, 3 tables
ZrN nucleation layer provides backside ohmic contact to MBE-grown GaN nanowires
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Stanislav Tiagulskyi, Roman Yatskiv, Marta Sobanka, Karol Olszewski, Zbigniew R. Zytkiewicz, Jan Grym
Self-assembled GaN nanowires are typically grown on Si substrates with convenient nucleation layers. Light-emitting devices based on arrays of GaN nanowires require that the nucleation layer is electrically conductive and optically nontransparent to prevent the absorption of generated light in the Si substrate. This study reports the molecular beam epitaxial growth of GaN nanowires on ZrN nucleation layers sputtered on sapphire and demonstrates that ZrN provides ohmic contact to dense vertical arrays of n-type GaN nanowires. The ohmic nature of the ZrN/n-type GaN nanowire contact is evidenced by the measurement of the current-voltage characteristics of individual as-grown nanowires using nanomanipulators in a scanning electron microscope. The limitations and advantages of single-nanowire measurements are discussed, and approaches to overcome these limitations are proposed. The feasibility of this concept is demonstrated by the measurement of single nanowire with a p-n junction, exhibiting highly rectifying characteristics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Bayesian optimization to infer parameters in viscoelasticity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Isaac Y. Miranda-Valdez, Tero Mäkinen, Juha Koivisto, Mikko J. Alava
Inferring viscoelasticity parameters is a key challenge that often leads to non-unique solutions when fitting rheological data. In this context, we propose a machine learning approach that utilizes Bayesian optimization for parameter inference during curve-fitting processes. To fit a viscoelastic model to rheological data, the Bayesian optimization maps the parameter values to a given error function. It then exploits the mapped space to identify parameter combinations that minimize the error. We compare the Bayesian optimization results to traditional fitting routines and demonstrate that our approach finds the fitting parameters in a less or similar number of iterations. Furthermore, it also creates a "white-box" and supervised framework for parameter estimation in linear viscoelasticity modeling.
Soft Condensed Matter (cond-mat.soft)
Origin of Enhanced Performance when Mn-Rich Rocksalt Cathodes transform to \(δ\)-DRX
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Shashwat Anand, Tara P. Mishra, Peichen Zhong, Yunyeong Choi, KyuJung Jun, Tucker Holstun, Gerbrand Ceder
Most Mn-rich cathodes are known to undergo phase transformation into structures resembling spinel-like ordering upon electrochemical cycling. Recently, the irreversible transformation of Ti-containing Mn-rich disordered rock-salt cathodes into a phase -- named \(\delta\) -- with nanoscale spinel-like domains has been shown to increase energy density, capacity retention, and rate capability. However, the nature of the boundaries between domains and their relationship with composition and electrochemistry are not well understood. In this work, we discuss how the transformation into the multi-domain structure results in eight variants of Spinel domains, which is crucial for explaining the nanoscale domain formation in the \(\delta\)-phase. We study the energetics of crystallographically unique boundaries and the possibility of Li-percolation across them with a fine-tuned CHGNet machine learning interatomic potential. Energetics of \(16d\) vacancies reveal a strong affinity to segregate to the boundaries, thereby opening Li-pathways at the boundary to enhance long-range Li-percolation in the \(\delta\) structure. Defect calculations of the relatively low-mobility Ti show how it can influence the extent of Spinel ordering, domain morphology and size significantly; leading to guidelines for engineering electrochemical performance through changes in composition.
Materials Science (cond-mat.mtrl-sci)
From pure to mixed: Altermagnets as intrinsic symmetry-breaking indicators
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-27 20:00 EST
We propose using altermagnetic phases as intrinsic symmetry-breaking indicators. The transmutation of pure into mixed altermagnets in the presence of spin-orbit coupling and the concomitant development of an anomalous Hall response can be associated with the breaking of specific lattice symmetries by external fields or the development of subleading order parameters. We introduce the basic ideas in the context of RuO\(_2\) and discuss the case of surface magnetism in Sr\(_2\)RuO\(_4\). Our study suggests that if Sr\(_2\)RuO\(_4\) hosts a pure altermagnet on its surface, the onset of specific superconducting states could transmute this altermagnet from pure to mixed and account for the apparent onset of time-reversal symmetry breaking (TRSB) at the superconducting transition temperature, without necessarily ascribing TRSB to the superconducting state. Further investigation of this unusual scenario could provide essential steps toward a more coherent picture of the phenomenology of this material.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Embodying mechano-fluidic memory in soft machines to program behaviors upon interactions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Alberto Comoretto, Tanaya Mandke, Johannes T.B. Overvelde
Soft machines display shape adaptation to external circumstances due to their intrinsic compliance. To achieve increasingly more responsive behaviors upon interactions without relying on centralized computation, embodying memory directly in the machines' structure is crucial. Here, we harness the bistability of elastic shells to alter the fluidic properties of an enclosed cavity, thereby switching between stable frequency states of a locomoting self-oscillating machine. To program these memory states upon interactions, we develop fluidic circuits surrounding the bistable shell, with soft tubes that kink and unkink when externally touched. We implement circuits for both long-term and short-term memory in a soft machine that switches behaviors in response to a human user and that autonomously changes direction after detecting a wall. By harnessing only geometry and elasticity, embodying memory allows physical structures without a central brain to exhibit autonomous feats that are typically reserved for computer-based robotic systems.
Soft Condensed Matter (cond-mat.soft), Robotics (cs.RO), Applied Physics (physics.app-ph)
Theory of Electro-Ionic Perturbations at Supported Electrocatalyst Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Yufan Zhang, Tobias Binninger, Jun Huang, Michael Eikerling
Nanoscopic heterogeneities in composition and structure are quintessential for the properties of electrocatalyst materials. Here, we present a semiclassical model to study the electrochemical properties of supported electrocatalyst nanoparticles (NP). The model captures the correlated electronic and ionic equilibration across NP, support, and electrolyte. It reveals peculiar trends in surface charging of the supported NP, validated by comparison with first-principles calculations. Support-induced perturbations in electronic and ionic charge densities at the NP's active surface manifest as distinct potentials of zero local electronic and ionic charges that could differ by more than 0.5 V in the studied system.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Phys Rev Lett 134, 066201 (2025)
Enhanced Efficiency in Shear-Loaded Brownian Gyrators
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-27 20:00 EST
Iman Abdoli, Abhinav Sharma, Hartmut Löwen
A Brownian gyrator is a system in which a particle experiences thermal noise from two distinct heat baths. This nonequilibrium setup inherently generates a nonzero torque, leading to gyrating motion around a potential energy minimum. As a minimal model for a heat engine, the Brownian gyrator provides valuable insights into energy conversion and nonequilibrium dynamics. Here, we investigate the effect of an externally imposed shear flow on a Brownian gyrator, treating it as a mechanical load. The shear flow introduces a tunable mechanism that allows the system to operate either as a heat engine, extracting work from the temperature gradient, or as a refrigerator, transferring heat from the colder to the hotter bath. Focusing on the heat engine regime, we analytically derive the steady-state probability distribution to compute the average torque exerted by the gyrator and quantify the mechanical power extracted from the shear. Our results show a remarkable increase in efficiency compared to the standard Brownian gyrator without shear, approaching Carnot efficiency at maximum power. Surprisingly, we also find that while the system can operate efficiently as a heat engine, it may become unstable before reaching the stall condition, highlighting a fundamental trade-off between efficiency and stability in shear-driven microscopic engines.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Thermalization in a simple spin-chain model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-27 20:00 EST
Peter Reimann, Christian Eidecker-Dunkel
We consider the common spin-1/2 XX-model in one dimension with open boundary conditions and a large but finite number of spins. The system is in thermal equilibrium at times t<0, and is subject to a weak local perturbation (quantum quench) at t=0. Focusing mainly on single-spin perturbations and observables, we show that the system re-thermalizes for sufficiently large times t>0 without invoking any unproven assumptions besides the basic laws of quantum mechanics. Moreover, the time-dependent relaxation behavior is obtained in quantitative detail and is found to exhibit a wealth of interesting features.
Statistical Mechanics (cond-mat.stat-mech)
Phys. Rev. B 111, 054312 (2025)
U(1) Dirac quantum spin liquid candidate in triangular-lattice antiferromagnet CeMgAl\(_{11}\)O\(_{19}\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-27 20:00 EST
Yantao Cao, Akihiro Koda, M. D. Le, V. Pomjakushin, Benqiong Liu, Zhendong Fu, Zhiwei Li, Jinkui Zhao, Zhaoming Tian, Hanjie Guo
Quantum spin liquid represents an intriguing state where electron spins are highly entangled yet spin fluctuation persists even at 0 K. Recently, the hexaaluminates MgAl\(_{11}\)O\(_{19}\) ( = rare earth) have been proposed to be a platform for realizing the quantum spin liquid state with dominant Ising anisotropic correlations. Here, we report detailed low-temperature magnetic susceptibility, muon spin relaxation, and thermodynamic studies on the CeMgAl\(_{11}\)O\(_{19}\) single crystal. Ising anisotropy is revealed by magnetic susceptibility measurements. Muon spin relaxation and ac susceptibility measurements rule out any long-range magnetic ordering or spin freezing down to 50 mK despite the onset of spin correlations below $$0.8 K. Instead, the spins keep fluctuating at a rate of 1.0(2) MHz at 50 mK. Specific heat results indicate a gapless excitation with a power-law dependence on temperature, \(C_m(T) \propto T^{\alpha}\). The quasi-quadratic temperature dependence with \(\alpha\) = 2.28(4) in zero field and linear temperature dependence in 0.25 T support the possible realization of the U(1) Dirac quantum spin liquid state.
Strongly Correlated Electrons (cond-mat.str-el)
Accepted by Sci. China - Phys. Mech. Astron. 7 pages main text + 8 pages supplementary materials
Majorana sweet spots in 3-site Kitaev chains
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Rodrigo A. Dourado, Martin Leijnse, Rubén Seoane Souto
Minimal Kitaev chains, composed of two quantum dots (QDs) connected via a superconductor, have emerged as an attractive platform to realize Majorana bound states (MBSs). These excitations exist when the ground state is degenerate. The additional requirement of isolating the MBS wavefunctions further restricts the parameter space to discrete sweet spots. While scaling up to Kitaev chains with more than two sites has the potential to improve the stability of the MBSs, longer chains offer more features to optimize, including the MBS localization length and the excitation gap. In this work, we theoretically investigate 3-site Kitaev chains and show that there are three different types of sweet spots, obtained by maximizing distinct MBS properties: genuine 3-site sweet spots with well-localized MBSs at the ends, effective 2-site sweet spots, where the middle site acts as a barrier, and sweet spots with delocalized MBSs that overlap in the middle of the chain. These three cases feature different degrees of robustness against perturbations, with the genuine 3-site being the most stable. We analyze the energy spectrum, transport, and microwave absorption associated with these three cases, showing how to distinguish them.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Spin and pair density waves in 2D altermagnetic metals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-27 20:00 EST
Nikolaos Parthenios, Pietro M. Bonetti, Rafael González-Hernández, Warlley H. Campos, Libor Šmejkal, Laura Classen
Altermagnetism, a recently proposed and experimentally confirmed class of magnetic order, features collinear compensated magnetism with unconventional d-, g-, or i-wave spin order. Here, we show that in a metallic 2D d-wave altermagnet with combined two-fold spin and four-fold lattice rotational symmetry \([C_2||C_4]\), secondary instabilities can arise. Using an unbiased functional renormalization group approach, we analyze the weak-coupling instabilities of a 2D Hubbard model with a preexisting altermagnetic order inspired by our ab initio electronic structure calculations of realistic material candidates from V\(_2\)X\(_2\)O (X = Te, Se) family. We identify two distinct spin density wave (SDW) states that break the underlying altermagnetic \([C_2||C_4]\) symmetry. Additionally, we find spin-fluctuation-induced instabilities leading to a singlet d-wave superconducting state and an unconventional commensurate pair density wave (PDW) state with extended s-wave and spin-triplet symmetry. We establish a general criterion for the unusual exchange statistics for these pair density waves and characterize their excitation spectrum, which exhibits Bogoliubov Fermi surfaces or nodal points depending on the gap size.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
11+9 pages, 4+6 figures
Time-Reversal Mirror inside a granular suspension: a way of measuring the ultrasound diffusion coefficient
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-27 20:00 EST
Y. Abraham, B. A. van Tiggelen, N. Benech, C. Negreira, X. Jia, A. Tourin
We demonstrate that the diffusion coefficient, \(D\), for ultrasound propagating in a multiple scattering medium, such as a dense granular suspension, can be measured using a time reversal experiment. This requires an unprecedented experimental setup in which a piezoelectric transducer, acting as a Time-Reversal Mirror (TRM), is embedded within the granular suspension at a depth much larger than the scattering mean free path, while an array of transducers is placed in the far field of the scattering sample. A single element of the array emits a short pulse and the TRM records the resulting ultrasonic field, which consists of a ballistic coherent wave followed by a coda wave. When the entire coda wave is time-reversed and re-emitted from the TRM, it is observed to refocus on the original source, with a focal spot size that decreases with the inverse depth of the TRM, characteristic of a diffusive regime. Time-reversal of short windows selected at different times \(t\) in the coda wave reveals a focal spot size that decreases as the inverse square root of time, i.e., \(1 / \sqrt{Dt}\). By fitting the predictions of a microscopic diffusion theory to our experimental data, we are able to accurately measure the diffusion coefficient in the granular suspension. Remarkably, this method does not require ensemble averaging due to stability of time-reversal against statistical fluctuations.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Quantum geometric moment encodes stacking order of moiré matter
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Surat Layek, Subhajit Sinha, Atasi Chakraborty, Ayshi Mukherjee, Heena Agarwal, Kenji Watanabe, Takashi Taniguchi, Amit Agarwal, Mandar M. Deshmukh
Exploring the topological characteristics of electronic bands is essential in condensed matter physics. Moiré materials featuring flat bands provide a versatile platform for engineering band topology and correlation effects. In moiré materials that break either time-reversal symmetry or inversion symmetry or both, electronic bands exhibit Berry curvature hotspots. Different stacking orders in these materials result in varied Berry curvature distributions within the flat bands, even when the band dispersion remains similar. However, experimental studies probing the impact of stacking order on the quantum geometric quantities are lacking. 1.4\(^\circ\) twisted double bilayer graphene (TDBG) facilitates two distinct stacking orders (AB-AB, AB-BA) and forms an inversion broken superlattice with electrically tunable flat bands. The valley Chern numbers of the flat bands depend on the stacking order, and the nonlinear Hall (NLH) effect distinguishes the differences in Berry curvature dipole (BCD), the first moment of Berry curvature. The BCD exhibits antisymmetric behavior, flipping its sign with the polarity of the perpendicular electric field in AB-AB TDBG, while it displays a symmetric behavior, maintaining the same sign regardless of the electric field's polarity in AB-BA TDBG. This approach electronically detects stacking-induced quantum geometry, while opening a pathway to quantum geometry engineering and detection.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Adv. Mater. 2025, 2417682
Tunable Josephson diode effect in singlet superconductor-altermagnet-triplet superconductor junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-27 20:00 EST
Lovy Sharma, Manisha Thakurathi
Recently discovered phase of collinear magnet called, altermagnet breaks time reversal symmetry (TRS), exhibits momentum-dependent spin-splitting of band structure with zero net magnetization. In this work, we theoretically investigate the Josephson junction (JJ) of spin singlet superconductor (SC)/altermagnet/spin triplet SC and demonstrate that it manifests field free Josephson diode effect (JDE). We illustrate that there are four key requisites to have JDE in such JJs, namely, broken TRS, left and right SC in the JJ shall be non-identical, presence of spin orbit interaction, and anisotropy in spin polarization at the Fermi surface or anisotropy in pair potential of the SC. It has also been shown that by applying a gate potential in the altermagnetic regime, one can not only reverse the sign of efficiency but also modulate its magnitude. Our system can be used as a superconducting rectifier that can be tuned efficiently using gate voltage and system parameters without having external magnetic field.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
9 pages, 6 figures
How to choose efficiently the size of the Bethe-Salpeter Equation Hamiltonian for accurate exciton calculations on supercells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-27 20:00 EST
Rafael R. Del Grande, David A. Strubbe
The Bethe-Salpeter Equation (BSE) is the workhorse method to study excitons in materials. The size of the BSE Hamiltonian, that is how many valence to conduction band transitions are considered in those calculations, needs to be chosen to be sufficiently large to converge excitons' energies and wavefunctions but should be minimized to make calculations tractable, as BSE calculations scale with the number of atoms as $ (N_{}^6)$. In particular, in the case of supercell (SC) calculations composed of \(N_{\rm{rep}}\) replicas of the primitive cell (PC), a natural choice to build this BSE Hamiltonian is to include all transitions from PC calculations by zone folding. However, this greatly increases the size of the BSE Hamiltonian, as the number of matrix elements in it is \((N_k N_c N_v)^2\), where \(N_k\) is the number of \(k\)-points, and \(N_{c(v)}\) is the number of conduction (valence) states. The number of \(k\)-points decreases by a factor \(N_{\rm{rep}}\) but both the number of conduction and valence states increase by the same factor, therefore the BSE Hamiltonian increases by a factor \(N_{\rm{rep}}^2\), making exactly corresponding calculations prohibitive. Here we provide an analysis to decide how many transitions are necessary to achieve comparable results. With our method, we show that to converge with an energy tolerance of 0.1 eV the first exciton binding energy of a LiF SC composed of 64 PCs, we only need 12% of the valence to conduction transitions that are given by zone folding. We also show that exciton energies are much harder to converge than Random Phase Approximation transition energies, underscoring the necessity of careful convergence studies. The procedure in our work helps in evaluating excitonic properties in large SC calculations such as defects, self-trapped excitons, polarons, and interfaces.
Materials Science (cond-mat.mtrl-sci)