CMP Journal 2025-05-02
Statistics
Nature Physics: 2
Physical Review Letters: 8
Physical Review X: 1
arXiv: 43
Nature Physics
Observation of the diffusive Nambu-Goldstone mode of a non-equilibrium phase transition
Original Paper | Bose-Einstein condensates | 2025-05-01 20:00 EDT
Ferdinand Claude, Maxime J. Jacquet, Quentin Glorieux, Michiel Wouters, Elisabeth Giacobino, Iacopo Carusotto, Alberto Bramati
Second-order phase transitions are governed by a spontaneous symmetry-breaking mechanism, which yields collective excitations with a gapless spectrum called Nambu-Goldstone modes. Although these modes propagate as sound waves in conservative systems, non-equilibrium phase transitions have been predicted to feature a diffusive Nambu-Goldstone mode. Here, we present the experimental characterization of such a mode in a non-equilibrium Bose-Einstein condensate of microcavity polaritons. The mode appears in the spectroscopic response of the condensate to an extra probe laser as spectral narrowing, along with the emergence of a tilted frequency plateau. Breaking the symmetry with another phase-fixing beam causes a gap to open in the imaginary part of the spectrum and the disappearance of the Nambu-Goldstone mode. These observations confirm theoretical predictions for the Nambu-Goldstone mode of non-equilibrium phase transitions and reveal the symmetry-breaking mechanism underlying polariton condensation.
Bose-Einstein condensates, Phase transitions and critical phenomena
Strongly interacting Meissner phases in large bosonic flux ladders
Original Paper | Quantum simulation | 2025-05-01 20:00 EDT
Alexander Impertro, SeungJung Huh, Simon Karch, Julian F. Wienand, Immanuel Bloch, Monika Aidelsburger
Periodically driven quantum systems can realize phases of matter that do not appear in time-independent Hamiltonians. One application is the engineering of synthetic gauge fields, which enables the study of topological many-body physics with neutral atom quantum simulators. Here we realize the strongly interacting Mott-Meissner phase–a state combining interaction-induced localization with chiral currents induced by an artificial magnetic field–in large-scale bosonic flux ladders with 48 sites at half-filling using a neutral atom quantum simulator. By combining quantum gas microscopy with local basis rotations, we reveal the emerging equilibrium particle currents with local resolution across large systems. We find chiral currents exhibiting a characteristic interaction scaling, providing direct experimental evidence of the interacting Mott-Meissner phase. Moreover, we benchmark density correlations with numerical simulations and find that the effective temperature of the system is on the order of the tunnel coupling. These results establish the feasibility of scaling periodically driven quantum systems to large, strongly correlated phases, enabling further studies of topological quantum matter with single-atom resolution and control.
Quantum simulation, Topological matter, Ultracold gases
Physical Review Letters
Simulating Sparse Hamiltonians on 2D Lattices
Research article | Quantum error correction | 2025-05-01 06:00 EDT
Harriet Apel and Nouédyn Baspin
Systems with sparse, yet long-range interactions, form a rich class capable of exhibiting various interesting physics, including good error correction. In this Letter we show how to simulate any sparse Pauli Hamiltonian with a 2D nearest neighbor Hamiltonian, using fewer resources than previous techniques. As an application we demonstrate how to simulate a good quantum code Hamiltonian, effectively approximating a $[[N,\mathrm{\Omega }(\sqrt{N}),\mathrm{\Omega }(\sqrt{N})]]$ code in two dimensions.
Phys. Rev. Lett. 134, 170602 (2025)
Quantum error correction, Quantum simulation
Leading Axion-Photon Sensitivity with NuSTAR Observations of M82 and M87
Research article | Formation & evolution of stars & galaxies | 2025-05-01 06:00 EDT
Orion Ning and Benjamin R. Safdi
Two independent teams have searched for axions using x-ray observations of entire galaxies, setting some of the strictest constraints to date on the properties of these dark matter candidates.
Phys. Rev. Lett. 134, 171003 (2025)
Formation & evolution of stars & galaxies, X ray astronomy, Axions, Solar interior, Stars
NuSTAR Bounds on Radiatively Decaying Particles from M82
Research article | Particle astrophysics | 2025-05-01 06:00 EDT
Francisco R. Candón, Damiano F. G. Fiorillo, Giuseppe Lucente, Edoardo Vitagliano, and Julia K. Vogel
Two independent teams have searched for axions using x-ray observations of entire galaxies, setting some of the strictest constraints to date on the properties of these dark matter candidates.
Phys. Rev. Lett. 134, 171004 (2025)
Particle astrophysics, Particle decays, X ray astronomy, Axion-like particles, Axions, Stars
Impact of Newly Measured $\beta $-Delayed Neutron Emitters around $^{78}\mathrm{Ni}$ on Light Element Nucleosynthesis in the Neutrino Wind Following a Neutron Star Merger
Research article | Beta decay | 2025-05-01 06:00 EDT
A. Tolosa-Delgado et al.
Neutron emission probabilities and half-lives of 37 $\beta $-delayed neutron emitters from $^{75}\mathrm{Ni}$ to $^{92}\mathrm{Br}$ were measured at the RIKEN Nishina Center in Japan, including 11 one-neutron and 13 two-neutron emission probabilities and six half-lives for the first time that supersede theoretical estimates. These nuclei lie in the path of the weak $r$ process occurring in neutrino-driven winds from the accretion disk formed after the merger of two neutron stars synthesizing elements in the $A\sim 80$ abundance peak. The presence of such elements dominates the accompanying kilonova emission over the first few days and have been identified in the AT2017gfo event, associated to the gravitational wave detection GW170817. Abundance calculations based on over 17 000 simulated trajectories describing the evolution of matter properties in the merger outflows show that the new data lead to an increase of 50%–70% in the abundance of Y, Zr, Nb, and Mo. This enhancement is large compared to the scatter of relative abundances observed in old very metal poor stars and thus is significant in the comparison with other possible astrophysical processes contributing to the light-element production. These results underline the importance of including experimental decay data for very neutron-rich $\beta $-delayed neutron emitters into $r$-process models.
Phys. Rev. Lett. 134, 172701 (2025)
Beta decay, Nucleosynthesis in explosive environments, 59 ≤ A ≤ 89, 90 ≤ A ≤ 149, Astrophysical & cosmological simulations, Nuclear data analysis & compilation, Radiation detectors, Radioactive beams
Anomalous Radiation Reaction in a Circularly Polarized Field
Research article | Laser driven electron acceleration | 2025-05-01 06:00 EDT
O. V. Kibis
Quantum corrections to electron dynamics in a circularly polarized electromagnetic field are found within the Floquet theory of periodically driven quantum systems. It is demonstrated that emission of photons by an electron rotating under the field leads to the quantum recoil force acting on the electron perpendicularly to the velocity of its forward movement, which differs crucially from the known classical recoil force directed oppositely to the velocity. Physically, such an anomalous radiation reaction arises from the one-loop QED correction to the photon emission and has no analog within the classical electrodynamics. Possible manifestations of this macroscopic QED effect are discussed for electrons in strong laser fields.
Phys. Rev. Lett. 134, 175001 (2025)
Laser driven electron acceleration, Quantum electrodynamics, Electrons, Two-dimensional electron gas
Half-Integer Quantum Hall States in Two-Dimensional Graphite
Research article | Anyons | 2025-05-01 06:00 EDT
Nicholas Mazzucca, Bishoy M. Kousa, Kenji Watanabe, Takashi Taniguchi, Allan H. MacDonald, and Marc W. Bockrath
Non-Abelian fractionalized quasiparticles in half-integer quantum Hall states have been proposed as a platform for the realization of topologically protected fault-tolerant qubits. We observe half-integer quantum Hall states out to remarkably large Landau level filling factors larger than 30 in dual-gated $\sim 3- 10\text{ }\text{ }\mathrm{nm}$-thick graphite devices. We identify most as single-component states stabilized by fractional correlations in exterior bilayers. Multicomponent (3,3,1) states with strong correlations between opposite-valley states on opposite sides of the graphite interior also appear. The facile integration of graphite with top and bottom surface gates makes thin film graphite an attractive platform to explore the physics of non-Abelian fractionalized quasiparticles.
Phys. Rev. Lett. 134, 176302 (2025)
Anyons, Edge states, Electrical properties, Landau levels, Quantum Hall effect, Graphite, Dilution refrigerator
Entangling Color Centers via Magnon-Antimagnon Pair Creation
Research article | Color centers | 2025-05-01 06:00 EDT
Eric Kleinherbers, Shane P. Kelly, and Yaroslav Tserkovnyak
We present how entanglement between a spatially separated pair of color centers can be created by letting them weakly interact with the quantum fluctuations of a nonequilibrium magnetic environment. To this end, we consider two coupled ferromagnets, one in the ground state and one in an inverted state with respect to an applied magnetic field. The resulting energetic instability leads to a quantum spin current in the vacuum state that is sustained by the creation of magnon-antimagnon pairs at the interface. We show that these quantum fluctuations imprint a steady-state entanglement onto the two dipole-coupled color centers through nonlocal dissipation. We derive conditions for establishing a maximally entangled Bell state. This entanglement is absent in thermal equilibrium.
Phys. Rev. Lett. 134, 176703 (2025)
Color centers, Dissipative dynamics, Quantum entanglement, Scattering theory, Spintronics, Squeezing of quantum noise, Ferromagnets, Qubits, Lindblad equation
Experimental Observation of Vortex Gyration Excited by Surface Acoustic Waves
Research article | Magnetic vortices | 2025-05-01 06:00 EDT
R. Lopes Seeger, F. Millo, G. Soares, J.-V. Kim, A. Solignac, G. de Loubens, and T. Devolder
We report experiments using magnetic resonance force microscopy to investigate the dynamics of magnetic vortices in submicrometer CoFeB disks grown on a piezoelectric substrate. We compare the vortex gyration excited inductively by microwave magnetic fields and through magnetoelastic coupling via surface acoustic waves (SAWs). Based on the device geometry and modeling performed, we find that the dominant mechanism for SAW-driven excitation is through lattice rotations, which generate an effective field localized at the vortex core. This contrasts with the magnetoelastic strains typically assumed in similar experiments. Moreover, we demonstrate that this magnetorotation torque can be tuned by applying a perpendicular magnetic field. Unlike spin wave excitations, nontrivial spin textures, such as vortices, effectively couple to magnetorotation torques, making them valuable probes for studying such phenomena.
Phys. Rev. Lett. 134, 176704 (2025)
Magnetic vortices, Magnetization dynamics, Magnetoacoustic effect, Magnetic force microscopy, Surface acoustic wave
Physical Review X
Topological Rigidity and Non-Abelian Defect Junctions in Chiral Nematic Systems with Effective Biaxial Symmetry
Research article | Topological defects | 2025-05-01 06:00 EDT
Jin-Sheng Wu, Roberto Abril Valenzuela, Mark J. Bowick, and Ivan I. Smalyukh
Engineered boundary conditions in chiral nematic liquid crystals enable the first experimental realization of non-Abelian line defects and their networks, revealing complex, ordered interactions and rich topological behavior.
Phys. Rev. X 15, 021036 (2025)
Topological defects, Liquid crystals, Topology
arXiv
Phonon Induced Energy Relaxation in Quantum Critical Metals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
Metals at the brink of electronic quantum phase transitions display high-temperature superconductivity, competing orders, and unconventional charge transport, revealing strong departures from conventional Fermi liquid behavior. Investigation of these fascinating intertwined phenomena has been at the center of research across a variety of correlated materials over the past many decades. A ubiquitous experimental observation is the emergence of a universal timescale that governs electrical transport and momentum relaxation. In this work, we analyze an equally important theoretical question of how the energy contained in the electronic degrees of freedom near a quantum phase transition relaxes to the environment via their coupling to acoustic phonons. Assuming that the bottleneck for energy dissipation is controlled by the coupling between electronic degrees of freedom and acoustic phonons, we present a universal theory of the temperature dependence of the energy relaxation rate in a marginal Fermi liquid. We find that the energy relaxation rate exhibits a complex set of temperature-dependent crossovers controlled by emergent energy scales in the problem. We place these results in the context of recent measurements of the energy relaxation rate via non-linear optical spectroscopy in the normal state of hole-doped cuprates.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
14 pages, 3 figures
Superfluid Weight of Inhomogeneous Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
Jonathan Schirmer, Enrico Rossi
In this work, we obtain the expression, within the linear response approximation, of the superfluid weight of a superconductor, taking into account the response of the superconductor’s pairing potential to the perturbing vector potential. We find that, in general, the correction is non-zero when the system is spatially non-uniform. We apply the formula to two exemplary cases: the case when strong inhomogeneities in the pairing potential are induced by a periodic potential, and the case when superconducting vortices are induced by an external magnetic field. For both cases we show that the correction to the superfluid weight due to the response of the paring potential to the perturbing vector potential can be significant, it must be included to obtain quantitatively correct results, and that for the case when vortices are present the expression of the superfluid weight that does not include such correction returns qualitatively wrong results.
Superconductivity (cond-mat.supr-con)
SDW driven “magnetic breakdown” in a d-wave altermagnet KV$_2$Se$_2$O
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Xu Yan, Ziyin Song, Juntao Song, Zhong Fang, Hongming Weng, Quansheng Wu
Altermagnets, combining zero net magnetization with intrinsic spin splitting, demonstrate unique quantum phenomena crucial for spintronic applications. KV$ _2$ Se$ _2$ O is proven to be a d-wave altermagnet with phase transition from a checkerboard-type (C-type) antiferromagnetic (AFM) state to a spin density wave (SDW) state as the temperature decreases. After phase transition, the apparent paradox emerges where angle-resolved photoemission spectroscopy (ARPES) reveals negligible Fermi surface modifications, while physical property measurement system (PPMS) measurements uncover substantial changes in transport properties. Our study explores the microscopic mechanisms governing phase-dependent transport properties of KV$ _2$ Se$ _2$ O base on first-principles calculations. The spin canting driven by periodic spin modulation in the SDW phase reduces the magnetic symmetry of KV$ _2$ Se$ _2$ O. The resultant band degeneracy lifting and Fermi surface reconstruction induce the ``magnetic breakdown” phenomenon, which alters carrier trajectories, modifies carrier concentration, strengthens electron-hole compensation, and ultimately accounts for the contrasting magnetic-field-dependent Hall resistivity relative to the C-type AFM state. Our work proposes an innovative method for identifying the electronic structure evolution across phase transitions from transport signatures, providing a novel paradigm for altermagnets research.
Materials Science (cond-mat.mtrl-sci)
Materials discovery acceleration by using condition generative methodology
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Caiyuan Ye, Yuzhi Wang, Xintian Xie, Tiannian Zhu, Jiaxuan Liu, Yuqing He, Lili Zhang, Junwei Zhang, Zhong Fang, Lei Wang, Zhipan Liu, Hongming Weng, Quansheng Wu
With the rapid advancement of AI technologies, generative models have been increasingly employed in the exploration of novel materials. By integrating traditional computational approaches such as density functional theory (DFT) and molecular dynamics (MD), existing generative models, including diffusion models and autoregressive models, have demonstrated remarkable potential in the discovery of novel materials. However, their efficiency in goal-directed materials design remains suboptimal. In this work we developed a highly transferable, efficient and robust conditional generation framework, PODGen, by integrating a general generative model with multiple property prediction models. Based on PODGen, we designed a workflow for the high-throughput crystals conditional generation which is used to search new topological insulators (TIs). Our results show that the success rate of generating TIs using our framework is 5.3 times higher than that of the unconstrained approach. More importantly, while general methods rarely produce gapped TIs, our framework succeeds consistently, highlighting an effectively $ \infty$ improvement. This demonstrates that conditional generation significantly enhances the efficiency of targeted material discovery. Using this method, we generated tens of thousands of new topological materials and conducted further first-principles calculations on those with promising application potential. Furthermore, we identified promising, synthesizable topological (crystalline) insulators such as CsHgSb, NaLaB$ _{12}$ , Bi$ _4$ Sb$ _2$ Se$ _3$ , Be$ _3$ Ta$ _2$ Si and Be$ _2$ W.
Materials Science (cond-mat.mtrl-sci)
EuAuSb: A helical variation on altermagnetism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
J. Sears (1), Juntao Yao (1 and 2), Zhixiang Hu (2), Wei Tian (3), Niraj Aryal (1), Weiguo Yin (1), A. M. Tsvelik (1), I. A. Zaliznyak (1), Qiang Li (1 and 4), J. M. Tranquada (1) ((1) Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, (2) Department of Materials Science and Chemical Engineering, Stony Brook University, (3) Neutron Scattering Division, Oak Ridge National Laboratory, (4) Department of Physics and Astronomy, Stony Brook University)
EuAuSb is a triangular-lattice Dirac semimetal in which a topological Hall effect has been observed to develop in association with a magnetically-ordered phase. Our single-crystal neutron diffraction measurements have identified an incommensurate helical order in which individual ferromagnetic Eu$ ^{2+}$ layers rotate in-plane by $ \sim$ 120$ ^{\circ}$ from one layer to the next. An in-plane magnetic field distorts the incommensurate order, eventually leading to a first order transition to a state that is approximately commensurate and that is continuously polarized as the bulk magnetization approaches saturation. From an analysis of the magnetic diffraction intensities versus field, we find evidence for a dip in the ordered in-plane moment at the same field where the topological Hall effect is a maximum, and we propose that this is due to field-induced quantum spin fluctuations. Our electronic structure calculations yield exchange constants compatible with the helical order and show that the bands near the Fermi level lose their spin degeneracy. The occurrence of spin-split bands in a magnetically ordered state with compensated moments suggests that this should be considered a helical flavor of altermagnetism.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Josephson Diode Effect from Nonequilibrium Current in a Superconducting Interferometer
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
Daniel Shaffer, Songci Li, Jaglul Hasan, Mikhail Titov, Alex Levchenko
We investigate the Josephson diode effect in a superconducting interferometer under nonequilibrium conditions. In contrast to its thermodynamic counterpart, which requires the simultaneous breaking of time-reversal and inversion symmetry, we demonstrate that a diode-like asymmetry of the critical current can emerge solely due to a dissipative current in the normal region of an otherwise symmetric Josephson junction. This effect is driven entirely by the nonequilibrium conditions, without the need for additional inversion symmetry breaking. Using the standard quasiclassical Keldysh Green’s function formalism, we explicitly calculate the diode coefficient from the supercurrent-phase relation of the interferometer. Remarkably, within certain ranges of control parameters, such as applied voltage, temperature, and the geometric aspect ratio of the device, the diode coefficient can exceed its nominal perfect value.
Superconductivity (cond-mat.supr-con)
8 pages, 2 figures
Nonlinear thermoelectric effects as a means to probe quantum geometry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
The quantum geometric tensor, which has the quantum metric and Berry curvature as its real and imaginary parts, plays a key role in the transport properties of condensed matter systems. In the nonlinear regime, the quantum metric dipole and Berry curvature dipole provide two distinct mechanisms for generating nonlinear Hall effects, which can both be experimentally observed in systems with suitable symmetries. In this work, we investigate the role of quantum geometry in nonlinear thermoelectric responses. We derive a series of nonlinear thermoelectric effects governed by the Berry curvature dipole and the quantum metric dipole, respectively. Among them, we identify a particularly interesting quantized thermoelectric response that directly measures the total chirality of Weyl points below the Fermi level. For general nonlinear responses, we derive the nonlinear analogs of the Wiedemann-Franz law and Mott’s formula. These provide a means to estimate the magnitude of nonlinear thermoelectric responses based on existing nonlinear Hall measurements. Our estimates suggest that these effects should be observable in several candidate materials, with In-doped Pb$ _{1-x}$ Sn$ _x$ Te standing out as the most promising. Our work offers new insights into the experimental study of quantum geometry through nonlinear thermoelectric measurements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12+3 pages, 6 figures
Contemporary tensor network approaches to gapless and topological phases in an extended Bose-Hubbard ladder
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-02 20:00 EDT
Yuma Watanabe, Ravindra W. Chhajlany, Maciej Lewenstein, Tobias Graß, Utso Bhattacharya
The development of numerically efficient computational methods has facilitated in depth studies of various correlated phases of matter including critical and topological phases. A quantum Monte-Carlo study of an extended Bose-Hubbard ladder has recently been used to identify an exotic phase with hidden order, where superfluid correlations coexist with string order, dubbed a Haldane superfluid (HSF). However, finite-size methods can struggle to uniquely determine the boundaries of quasi-long-range ordered states with nonlocal, e.g. string-like, correlations. In the present Letter, we revisit the HSF scenario using tensor network algorithms specialized for finite/infinite (quasi-)1D systems, \textit{i.e.} the well-governed finite-size density matrix renormalization group (DMRG), and the state-of-the-art infinite-size variational uniform matrix product state (VUMPS) methods. While DMRG results extrapolated to the thermodynamic limit are compatible with a putative HSF, the results from the VUMPS calculations provide sharper phase boundaries that leave no room for such a topological superfluid. Our results demonstrate the crucial advantage of the VUMPS in characterizing topological and critical interacting phases providing the precise phase boundaries.
Quantum Gases (cond-mat.quant-gas)
Rare Trajectories in a Prototypical Mean-field Disordered Model: Insights into Landscape and Instantons
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-02 20:00 EDT
Patrick Charbonneau, Giampaolo Folena, Enrico M. Malatesta, Tommaso Rizzo, Francesco Zamponi
For disordered systems within the random first-order transition (RFOT) universality class, such as structural glasses and certain spin glasses, the role played by activated relaxation processes is rich to the point of perplexity. Over the last decades, various efforts have attempted to formalize and systematize such processes in terms of instantons similar to the nucleation droplets of first- order phase transitions. In particular, Kirkpatrick, Thirumalai, and Wolynes proposed in the late ‘80s an influential nucleation theory of relaxation in structural glasses. Already within this picture, however, the resulting structures are far from the compact objects expected from the classical droplet description. In addition, an altogether different type of single-particle hopping-like instantons has recently been isolated in molecular simulations. Landscape studies of mean-field spin glass models have further revealed that simple saddle crossing does not capture relaxation in these systems. We present here a landscape-agnostic study of rare dynamical events, which delineates the richness of instantons in these systems. Our work not only captures the structure of metastable states, but also identifies the point of irreversibility, beyond which activated relaxation processes become a fait accompli. An interpretation of the associated landscape features is articulated, thus charting a path toward a complete understanding of RFOT instantons.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
30 pages, 16 figures
Interlayer Coupling-Induced Quantum Phase Transition in Quantum Anomalous Hall Multilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Ling-Jie Zhou, Deyi Zhuo, Ruobing Mei, Yi-Fan Zhao, Kaijie Yang, Ruoxi Zhang, Zijie Yan, Han Tay, Moses H. W. Chan, Chao-Xing Liu, Cui-Zu Chang
A quantum phase transition arises from competition between different ground states and is typically accessed by varying a single physical parameter near absolute zero temperature. The quantum anomalous Hall (QAH) effect with high Chern number C has recently been achieved in magnetic topological insulator (TI) multilayers. In this work, we employ molecular beam epitaxy to synthesize a series of magnetic TI penta-layers by varying the thickness of the middle magnetic TI layer, designated as m quintuple layers. Electrical transport measurements demonstrate a quantum phase transition between C = 1 and C = 2 QAH states. For m 1 and m 2, the sample exhibits the well-quantized C = 1 and C = 2 QAH states, respectively. For 1 m 2, we observe a monotonic decrease in Hall resistance from h/e2 to h/2e2 with increasing m, accompanied by a peak in the longitudinal resistance. The quantum phase transition between C = 1 and C = 2 QAH states is attributed to the weakening of the interlayer coupling between the top and the bottom C = 1 QAH layers. Our findings provide a scalable strategy for engineering QAH devices with a tunable Chern number. This approach enables precise control and enhanced functionality in chiral edge current-based electronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
22 pages and 4 figures. Comments are welcome
Symmetry induced pairing in dark excitonic condensate at finite temperature
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-02 20:00 EDT
Adham Alkady, Anatoly B. Kuklov
Bose Einstein condensate of optically inactive (dark) intervalley excitons must be inherently multi-component because of the point group and the time-reversal symmetries of a crystal. Accordingly, a number of the condensate components N$ _v$ is determined by the symmetry. Since the valleys hosting such excitons are separated by large quasi-momenta, the minimal inter-component Josephson-type coupling can only be established between pairs of excitons from the time-reversed valleys. As a result, a paired condensate can emerge at finite temperature, that is, the phase where individual valleys are not characterized by the condensate order, while the order exists for the pairs from the time-reversed valleys. This prediction follows from the elementary mean field analysis regardless of the dimensionality. However, as Monte Carlo simulations show, no such a phase exists in 3D crystals. Instead, the N$ _v$ -component condensation proceeds as the Ist order transition from the normal state. The paired phase does exist in 2D for N$ _v\geq 6$ . It forms by Berezinskii-Kosterlitz-Thouless transition from the high temperature (normal) phase. Upon further lowering temperature, a second transition transforms the paired phase into the N$ _v$ -component condensate.
Statistical Mechanics (cond-mat.stat-mech), Optics (physics.optics)
Adham passed away before this project was completed
Twist Engineering of Anisotropic Excitonic and Optical Properties of a Two-Dimensional Magnetic Semiconductor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Qiuyang Li, Xiaohan Wan, Senlei Li, Adam Alfrey, Wenhao Liu, Zixin Zhai, Wyatt Alpers, Yujie Yang, Irmina Wladyszewska, Christiano W. Beach, Liuyan Zhao, Bing Lv, Chunhui Rita Du, Kai Sun, Hui Deng
Two dimensional (2D) van der Waals (vdW) magnetic semiconductors are a new class of quantum materials for studying the emergent physics of excitons and spins in the 2D limit. Twist engineering provides a powerful tool to manipulate the fundamental properties of 2D vdW materials. Here, we show that twist engineering of the anisotropic ferromagnetic monolayer semiconductor, CrSBr, leads to bilayer magnetic semiconductors with continuously tunable magnetic moment, dielectric anisotropy, exciton energy and linear dichroism. We furthermore provide a model for exciton energy in the media with tunable anisotropy. These results advance fundamental studies on 2D vdW materials and open doors to applications to nano-optics, twistronics, and spintronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 4 figures
Roadmap on Advancements of the FHI-aims Software Package
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Joseph W. Abbott, Carlos Mera Acosta, Alaa Akkoush, Alberto Ambrosetti, Viktor Atalla, Alexej Bagrets, Jörg Behler, Daniel Berger, Björn Bieniek, Jonas Björk, Volker Blum, Saeed Bohloul, Connor L. Box, Nicholas Boyer, Danilo Simoes Brambila, Gabriel A. Bramley, Kyle R. Bryenton, María Camarasa-Gómez, Christian Carbogno, Fabio Caruso, Sucismita Chutia, Michele Ceriotti, Gábor Csányi, William Dawson, Francisco A. Delesma, Fabio Della Sala, Bernard Delley, Robert A. DiStasio Jr., Maria Dragoumi, Sander Driessen, Marc Dvorak, Simon Erker, Ferdinand Evers, Eduardo Fabiano, Matthew R. Farrow, Florian Fiebig, Jakob Filser, Lucas Foppa, Lukas Gallandi, Alberto Garcia, Ralf Gehrke, Simiam Ghan, Luca M. Ghiringhelli, Mark Glass, Stefan Goedecker, Dorothea Golze, James A. Green, Andrea Grisafi, Andreas Grüneis, Jan Günzl, Stefan Gutzeit, Samuel J. Hall, Felix Hanke, Ville Havu, Xingtao He, Joscha Hekele, Olle Hellman, Uthpala Herath, Jan Hermann, Daniel Hernangómez-Pérez, Oliver T. Hofmann, Johannes Hoja, Simon Hollweger, Lukas Hörmann, Ben Hourahine, Wei Bin How, William P. Huhn, Marcel Hülsberg, Sara Panahian Jand, Hong Jiang, Erin R. Johnson, Werner Jürgens, J. Matthias Kahk, Yosuke Kanai, Kisung Kang, Petr Karpov, Elisabeth Keller, Roman Kempt, Danish Khan, Matthias Kick, Benedikt P. Klein, Jan Kloppenburg, Alexander Knoll, Florian Knoop, Franz Knuth, Simone S. Köcher, Jannis Kockläuner, Sebastian Kokott, Thomas Körzdörfer, Hagen-Henrik Kowalski, Peter Kratzer, Pavel Kůs, Raul Laasner, Bruno Lang, Björn Lange, Marcel F. Langer, Ask Hjorth Larsen, Hermann Lederer, Susi Lehtola, Maja-Olivia Lenz-Himmer
Electronic-structure theory is the foundation of the description of materials including multiscale modeling of their properties and functions. Obviously, without sufficient accuracy at the base, reliable predictions are unlikely at any level that follows. The software package FHI-aims has proven to be a game changer for accurate free-energy calculations because of its scalability, numerical precision, and its efficient handling of density functional theory (DFT) with hybrid functionals and van der Waals interactions. It treats molecules, clusters, and extended systems (solids and liquids) on an equal footing. Besides DFT, FHI-aims also includes quantum-chemistry methods, descriptions for excited states and vibrations, and calculations of various types of transport. Recent advancements address the integration of FHI-aims into an increasing number of workflows and various artificial intelligence (AI) methods. This Roadmap describes the state-of-the-art of FHI-aims and advancements that are currently ongoing or planned.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
arXiv admin note: Includes articles arXiv:2502.02460, arXiv:2501.02550, arXiv:2411.01680, arXiv:2501.16091, arXiv:2411.04951
Expanding Active Matter to the Third Dimension: Exploring Short and Long-Range Particle-Wall Interactions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-02 20:00 EDT
Sandeep Ramteke, Jordan Dehmel, Touvia Miloh, Jarrod Schiffbauer, Alicia Boymelgreen
Most active colloid experiments are quasi-2D. Here a 3D density-matched solution of active particles propelled and aligned with an AC electric field uniquely facilitates measurement of short and long-range particle-wall interactions. Near-wall mobility is reduced by Stokes drag and local electric-field distortion. Long-range attractions concentrate particles at upper and lower walls at a ratio dependent on particle orientation and rate proportional to speed and confinement. This approach may be extended to other active systems to understand particle-wall interactions and non-equilibrium phenomena.
Soft Condensed Matter (cond-mat.soft)
Number of pages 8 and number of figures 4
Thermodynamic potentials from a probabilistic view on the system-environment interaction energy
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-02 20:00 EDT
Mohammad Rahbar, Christopher J. Stein
In open systems with strong coupling, the interaction energy between the system and the environment is significant, so thermodynamic quantities cannot be reliably obtained by traditional statistical mechanics methods. The Hamiltonian of mean force $ \mathcal{H}^{\ast}{\beta}$ offers an in principle accurate theoretical basis by explicitly accounting for the interaction energy. However, calculating the Hamiltonian of mean force is challenging both theoretically and computationally. We demonstrate that when the condition $ \text{Var}{\mathcal{E}0} (e^{-\beta {V}{\mathcal{SE}}}) = 0$ is met, the dependence of thermodynamic variables can be shifted from $ {P_{\beta}(x_{\mathcal{S}}), \mathcal{H}^{\ast}{\beta}(x{\mathcal{S}})}$ to $ {P_{\beta}(x_{\mathcal{S}}), P(V_{\mathcal{SE}})}$ . This change simplifies thermodynamic measurements. As a central result, we derive a general equality that holds for arbitrary coupling strengths and from which an inequality follows - aligned with Jensen’s inequality applied to the Gibbs-Bogoliubov-Feynman bound. This equality, analogous in importance to the Jarzynski equality, offers deeper insight into free energy differences in strongly coupled systems. Finally, by combining our result with said Jarzynski equality, we derive additional relations that further clarify thermodynamic behavior in strongly coupled open systems.
Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Dominant apical-oxygen electron-phonon coupling in HgBa$_2$Ca$_2$Cu$3$O${8+δ}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
Wenshan Hong, Qizhi Li, Shilong Zhang, Qian Xiao, Sahil Tippireddy, Jie Li, Yuchen Gu, Shichi Dong, Taimin Miao, Xiangyu Luo, Xianghong Jin, Lin Zhao, Xingjiang Zhou, Ke-Jin Zhou, Yi Lu, Yingying Peng, Yuan Li
How electron-phonon interactions influence high-temperature superconductivity in cuprates remains contested, and their role outside the CuO$ _2$ planes has been largely overlooked. The most conspicuous evidence for such coupling is the ubiquitous 70-meV dispersion kink seen by photoemission, yet its microscopic origin is still debated. Here we use oxygen-$ K$ -edge resonant inelastic X-ray scattering (RIXS) to probe the trilayer cuprate HgBa$ _2$ Ca$ _2$ Cu$ _3$ O$ _{8+\delta}$ (Hg1223). When both incident photon energy and polarization are tuned to the apical-oxygen $ 1s!\rightarrow!2p_z$ transition, the RIXS spectra exhibit a ladder of at least ten phonon overtones, evenly spaced by 70 meV, whose intensities follow a Franck-Condon envelope, signalling exceptionally strong electron-phonon coupling. Quantitative modelling that incorporates core-hole lifetime evaluation yields an apical-phonon coupling energy of 0.25(1) eV, significantly larger than that of the planar stretching mode. Such a coupling strength offers a strong contender for explaining the universal 70-meV kink and suggests that the dominant electron-phonon channel resides outside the CuO$ _2$ planes. By elevating inter-layer lattice dynamics from a peripheral factor to a central actor, our results provide a fresh starting point for theories seeking to reconcile strong correlations, lattice dynamics and high-temperature superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
33 pages, 15 figures; comments are welcome
Wilson polygons and the topology of zero-dimensional systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Gen Yin, Rameswar Bhattacharjee, Miklos Kertesz
We show that zero-dimensional (0-D) systems can host non-trivial topology analogous to macroscopic topological materials in greater dimensions. Unlike macroscopic periodic systems with translational symmetry, zero-dimensional materials such as molecules, clusters and quantum dots can exhibit discrete rotation symmetry. The eigenstates can thus be grouped into discrete bands and Bloch-like wave functions. Since the symmetry is discrete, the Berry phase and the topological indices must be defined by discrete Wilson polygons. Here, we demonstrate non-trivial Z2 orders in two representative 0-D molecules, [m]-Cycloparaphenylene and [m]-iso-thianaphthene, where topological transitions occur when modifying the coupling between the repeating units. Similar to macroscopic topological systems in greater dimensions, localized boundary states emerge in composite nanohoops formed by segments that are topologically distinct. This opens up the possibility of non-trivial topological phases in 0-D systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Explorative Curriculum Learning for Strongly Correlated Electron Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
Kimihiro Yamazaki, Takuya Konishi, Yoshinobu Kawahara
Recent advances in neural network quantum states (NQS) have enabled high-accuracy predictions for complex quantum many-body systems such as strongly correlated electron systems. However, the computational cost remains prohibitive, making exploration of the diverse parameters of interaction strengths and other physical parameters inefficient. While transfer learning has been proposed to mitigate this challenge, achieving generalization to large-scale systems and diverse parameter regimes remains difficult. To address this limitation, we propose a novel curriculum learning framework based on transfer learning for NQS. This facilitates efficient and stable exploration across a vast parameter space of quantum many-body systems. In addition, by interpreting NQS transfer learning through a perturbative lens, we demonstrate how prior physical knowledge can be flexibly incorporated into the curriculum learning process. We also propose Pairing-Net, an architecture to practically implement this strategy for strongly correlated electron systems, and empirically verify its effectiveness. Our results show an approximately 200-fold speedup in computation and a marked improvement in optimization stability compared to conventional methods.
Strongly Correlated Electrons (cond-mat.str-el), Machine Learning (cs.LG)
Altermagnetic band splitting in 10 nm epitaxial CrSb thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Sandra Santhosh, Yongxi Ou, Supriya Ghosh, Paul Corbae, Wilson J. Yanez-Parreno, Alexei V. Fedorov, Makoto Hashimoto, Donghui Lu, Christopher J. Jensen, Julie A. Borchers, Alexander J. Grutter, Timothy R. Charlton, Anthony Richardella, K. Andre Mkhoyan, Christopher J. Palmstrøm, Nitin Samarth
Altermagnets are a newly identified family of collinear antiferromagnets with momentum-dependent spin-split band structure of non-relativistic origin, derived from spin-group symmetry-protected crystal structures. Among candidate altermagnets, CrSb is attractive for potential applications because of a large spin-splitting near the Fermi level and a high Neel transition temperature of around 700 K. We use molecular beam epitaxy to synthesize CrSb (0001) thin films with thicknesses ranging from 10 nm to 100 nm. Structural characterization, using reflection high energy electron diffraction, scanning transmission electron microscopy, and X-ray diffraction, demonstrates the growth of epitaxial films with good crystallinity. Polarized neutron reflectometry shows the absence of any net magnetization, consistent with antiferromagnetic order. In vacuo angle resolved photoemission spectroscopy (ARPES) measurements probe the band structure in a previously unexplored regime of film thickness, down to 10 nm. These ARPES measurements show a three-dimensional momentum-dependent band splitting of up to 1 eV with g-wave symmetry, consistent with that seen in prior studies of bulk single crystals. The distinct altermagnetic band structure required for potential spin-transport applications survives down to the 10 nm thin film limit at room temperature.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Revisiting the physical properties of (LaS)1+d(NbS2) misfit-layered compounds
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
Masanori Nagao, Dan Mouri, Yuki Maruyama, Akira Miura, Yoshihiko Takano, Satoshi Watauchi
Electrical transport in polycrystalline and single-crystalline (LaS)1+d(NbS2) misfit-layered compounds was measured. Polycrystalline samples were synthesized using S raw materials of different purities (2N or 6N), and single-crystalline samples were grown using two types of transport agents (2NH4Cl+PbCl2 or NH4Cl) via the chemical vapor transport method. The temperature dependence on resistivity dropped at 1.3-2.0 K for some of the samples, which might be affected by the unknown impurity. (LaS)1+d(NbS2) misfit-layered compounds for the main phase of those obtained samples exhibited no superconductivity above 0.2 K by the resistivity measurement.
Superconductivity (cond-mat.supr-con)
5 figures, 2 tables
Solid State Communications, vol.403 (2025) 115980
Emergent Synaptic Plasticity from Tunable Dynamics of Probabilistic Bits
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-02 20:00 EDT
Sagnik Banerjee, Shiva T. Konakanchi, Supriyo Datta, Pramey Upadhyaya
Probabilistic (p-) computing, which leverages the stochasticity of its building blocks (p-bits) to solve a variety of computationally hard problems, has recently emerged as a promising physics-inspired hardware accelerator platform. A functionality of importance for p-computers is the ability to program-and reprogram-the interaction strength between arbitrary p-bits on-chip. In natural systems subject to random fluctuations, it is known that spatiotemporal noise can interact with the system’s nonlinearities to render useful functionalities. Leveraging that principle, here we introduce a novel scheme for tunable coupling that inserts a ‘’hidden’’ p-bit between each pair of computational p-bits. By modulating the fluctuation rate of the hidden p-bit relative to the synapse speed, we demonstrate both numerically and analytically that the effective interaction between the computational p-bits can be continuously tuned. Moreover, this tunability is directional, where the effective coupling from one computational p-bit to another can be made different from the reverse. This synaptic-plasticity mechanism could open new avenues for designing (re-)configurable p-computers and may inspire novel algorithms that leverage dynamic, hardware-level tuning of stochastic interactions.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
A$_1$-A$_2$ splitting in pure $^3$He in nematic aerogel
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
V.V. Dmitriev, M.S. Kutuzov, D.V. Petrova, A.A. Soldatov, A.N. Yudin
Here, we present the results of vibrating wire experiments in pure $ ^3$ He (without $ ^4$ He coverage) in nematic aerogel. We investigated the dependence of splitting of the superfluid transition temperature of $ ^3$ He in aerogel on magnetic field. In addition to our previous work, we used a wider range of magnetic fields (up to 31 kOe) and managed to detect both the “upper” and “lower” superfluid transition temperatures. The solid paramagnetic $ ^3$ He layer on the aerogel strands activates the magnetic scattering channel. According to theory, it should result in linear splitting at high ($ \ge20$ kOe) fields, while at lower fields the splitting is expected to be nonlinear. We were able to observe this nonlinearity, but we have a discrepancy with theoretical predictions regarding the range of fields where nonlinearity occurs. Possible reasons for this are discussed.
Superconductivity (cond-mat.supr-con), Other Condensed Matter (cond-mat.other)
6 pages, 5 figures
Non-reciprocal anti-aligning active mixtures: deriving the exact Boltzmann collision operator
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-02 20:00 EDT
We consider the effect of non-reciprocity in a binary mixture of self-propelled particles with anti-aligning interactions, where a particle of type A reacts differently to a particle of type B than vice versa. Starting from a well-known microscopic Langevin-model for the particles, setting up the corresponding exact N-particle Fokker-Planck equation and making Boltzmann’s assumptions of low density and one-sided molecular chaos, the non-linear active Boltzmann equation with the exact collision operator is derived. In this derivation, the effect of phase-space compression and the build-up of pair-correlations during binary interactions is explicitly taken into account, leading to a theoretical description beyond mean-field. This extends previous results for reciprocal interactions, where it was found that orientational order can emerge in a system with purely anti-aligning interactions. Although the equations of motion are more complex than in the reciprocal system, the theory still leads to analytical expressions and predictions. Comparisons with agent-based simulations show excellent quantitative agreement of the dynamic and static behavior in the low density and/or small coupling limit.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
32 pages, 4 figures
Site-Percolation-Driven Ionic Conductivity in Random Substitutional Crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Rikuya Ishikawa, Kyohei Takae, Rei Kurita
The design of superionic conductors for all-solid-state batteries often faces a fundamental trade-off between stability and ionic conductivity. Random Substitutional Crystals (RSCs), where atomic species are randomly distributed throughout a crystal lattice, present a promising route to overcome this competitive relation. Although extensive studies have focused on local ionic hopping, the role of mesoscale structural organization in determining macroscopic conductivity remains poorly understood, limiting the rational design of optimal compositions. Here, we systematically investigate the ionic conductivity of NaCl-type RSCs as a function of composition using molecular dynamics simulations. We find that ionic conductivity increases sharply once the carrier ion concentration exceeds a critical threshold, without disrupting the underlying crystal structure. Strikingly, this threshold aligns with the site percolation threshold predicted by percolation theory. Our findings establish ion percolation as a universal design principle that reconciles the trade-off between conductivity and stability, offering a simple and broadly applicable strategy for the development of robust, high-performance solid electrolytes.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
Tuning relaxation and nonlinear upconversion of valley-exciton-polaritons in a monolayer semiconductor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Hangyong Shan, Jamie M. Fitzgerald, Roberto Rosati, Gilbert Leibeling, Kenji Watanabe, Takashi Taniguchi, Seth Ariel Tongay, Falk Eilenberger, Martin Esmann, Sven Höfling, Ermin Malic, Christian Schneider
Controlling exciton relaxation and energy conversion pathways via their coupling to photonic modes is a central task in cavity-mediated quantum materials research. In this context, the light-matter hybridization in optical cavities can lead to intriguing effects, such as modified carrier transport, enhancement of optical quantum yield, and control of chemical reaction pathways. Here, we investigate the impact of the strong light-matter coupling regime on energy conversion, both in relaxation and upconversion schemes, by utilizing a strongly charged MoSe2 monolayer embedded in a spectrally tunable open-access cavity. We find that the charge carrier gas yields a significantly modified photoluminescence response of cavity exciton-polaritons, dominated by an intra-cavity like pump scheme. In addition, upconversion luminescence emerges from a population transfer from fermionic trions to bosonic exciton-polaritons. Due to the availability of multiple optical modes in the tunable open cavity, it seamlessly meets the cavity-enhanced double resonance condition required for an efficient upconversion. The latter can be actively tuned via the cavity length in-situ, displaying nonlinear scaling in intensity and fingerprints of the valley polarization. This suggests mechanisms that include both trion-trion Auger scattering and phonon absorption as its underlying microscopic origin.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Size-Dependent Tensile Behavior and Dislocation Dynamics in Cu and Ag Nanowires: A Molecular Dynamics Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
By using molecular dynamics simulations, the research examine how copper and silver nanowires respond to tensile loading in order to clarify their nanoscale deformation mechanisms. The results demonstrate that these two metal nanowires follow notably different stress - strain trends, with silver wires exhibiting greater elastic stiffness and higher yield points at equivalent diameters - an effect likely rooted in silver’s stronger atomic bonding and more stable microstructure. A pronounced size effect is observed: as the wire diameter diminishes, both the yield strength and ultimate tensile strength increase substantially, a behavior driven by the higher proportion of surface atoms that enhance dislocation nucleation and mobility. Atomistic analyses further underscore the dominant role of dislocations during plastic deformation, and in particular reveal that surface - initiated dislocations in thinner wires critically affect their fracture behavior.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Characterizing the dissolution states of a fluorescent probe within a lipid bilayer using molec ular dynamics simulations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-02 20:00 EDT
Ryo Okabe, Natsuumi Ito, Yuya Matsubara, Nozomi Morishita Watanabe, Hiroshi Umakoshi, Kento Kasahara, Nobuyuki Matubayasi
The physicochemical properties of lipid bilayers (membranes) are closely associated with various cellular functions and are often evaluated using absorption and fluorescence spectroscopies. For instance, by employing fluorescent probes that exhibit spectra reflective of the surrounding membrane environment, one can estimate the membrane polarity. Thus, elucidating how such probes are dissolved within the membranes would be beneficial for enabling a deeper interpretation of the spectra. Here, we apply molecular dynamics (MD) simulation with an enhanced sampling method to investigate the dissolution state of 6-propionyl-2-dimethylaminonaphthalene (Prodan) within a membrane composed of 1,2-dioleoyl-\textit{sn}-glycero-3-phosphocholine (DOPC), as well as its variation upon the addition of ethanol as a cosolvent to the aqueous phase. In the absence of ethanol, it is found that the bulky moieties of Prodan (propionyl and dimethylamine groups) prefer to be oriented toward the membrane center owing to the voids existing near the center. The structural change in the membrane induced by the addition of ethanol causes a reduction in the void population near the center, resulting in a diminished orientation preference of Prodan.
Soft Condensed Matter (cond-mat.soft)
Main: 9 pages, SI: 3 pages
Effect of Ti$_2$Pd(Ni) on the Transformation Behavior in Sputtered Ti-rich TiNiPd Shape Memory Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Lars Bumke (1), Niklas Wolff (2), Lorenz Kienle (2), Eckhard Quandt (1) ((1) Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, Kiel University, Germany, (2) Synthesis and Real Structure, Institute for Materials Science, Faculty of Engineering, Kiel University, Germany)
TiNiPd based shape memory alloys (SMAs) share similar microstructural features as TiNiCu-based SMAs known for their exceptional resistance to functional fatigue due to their high crystallographic compatibility, nanometer sized grains and coherent precipitates, making them an ideal system to further explore the critical factors influencing cyclic stability. In this study, we investigate the effect of heat treatments (500 °C, 600 °C, 700 °C and 800 °C) on the cyclic stability and microstructure of free-standing, magnetron-sputtered Ti$ _{53.6}$ Ni$ _{35.2}$ Pd$ _{11.2}$ films. All heat treatments promote the formation of Ti$ _2$ Pd(Ni) precipitates and result in a similar grain size (~1-4 $ \mu$ m). Lower heat treatment temperatures improve the cyclic stability of the stress induced transformation while reducing transformation temperatures and latent heat. Temperature dependent X-ray diffraction reveals a complex microstructure for the martensite phase with Ti$ _2$ Pd(Ni), Ti$ _2$ Ni(Pd), TiNiPd(B2), B19/B19$ ‘$ and R-phase. The thermal phase transition changes from a distinct 1st order to a 2nd order like transition, accompanied by increasing amount of remanent austenite and R-phase, with nearly no change for the sample heat treated at 500 °C. In situ stress dependent X-ray diffraction demonstrates a significant difference between the temperature and stress induced phase transformation for this heat treatment. The observed semi crystalline microstructure, featuring nano domains of Ti$ _2$ Pd(Ni) precipitates in the sample heat-treated at 500 °C, leads to a mixture of long range martensitic and strain glass transition. This study highlights the impact of heat treatment and microstructure on the phase transformation behavior and functional fatigue in Ti-rich TiNiPd alloys.
Materials Science (cond-mat.mtrl-sci)
15 pages (20 with SI), 6 figures (19 with SI)
Approximate calculation of functional integrals arising from the operator approach
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-02 20:00 EDT
Edik Ayryan, Ján Buša, Michal Hnatič, Tomáš Lučivjanský, Victor Malyutin
We apply the operator approach to a stochastic system belonging to a class of death-birth processes, which we introduce utilizing the master equation approach. By employing Doi- Peliti formalism we recast the master equation in the form of a Schrödinger-like equation. Therein appearing pseudo-Hamiltonian is conveniently expressed in a suitable Fock space, constructed using bosonic-like creation and annihilation operators. The kernel of the associated time evolution operator is rewritten using a functional integral, for which we propose an approximate method that allows its analytical treatment. The method is based on the expansion in eigenfunctions of the Hamiltonian generating given functional integral. In this manner, we obtain approximate values for the probabilities of the system being in the first and second states for the case of the pure birth process.
Statistical Mechanics (cond-mat.stat-mech)
Physica A 670 (2025) 130616
Photoengineering the Magnon Spectrum in an Insulating Antiferromagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
V. Radovskaia, R. Andrei, J.R. Hortensius, R.V. Mikhaylovskiy, R. Citro, S. Chattopadhyay, M.X. Na, B.A. Ivanov, E. Demler, A.V. Kimel, A.D. Caviglia, D. Afanasiev
Femtosecond optical pulses have opened a new frontier in ultrafast dynamics, enabling direct access to fundamental interactions in quantum materials. In antiferromagnets (AFMs), where the fundamental quantum mechanical exchange interaction governs spin dynamics, this access is especially compelling, enabling the excitation of magnons - collective spin-wave modes - that naturally reach terahertz (THz) frequencies and supersonic velocities. Femtosecond optical pulses provided a route to coherently excite such magnons across the entire Brillouin zone. Controlling their spectral properties - such as the magnon gap and dispersion - represents the next monumental step, enabling dynamic tuning of group velocities, coherence, and interaction pathways. Yet, achieving this remains a challenge, requiring ultrafast and long-lasting manipulation of the underlying exchange interaction. Here, we show that in DyFeO3 - an insulating AFM with strongly coupled electronic and magnetic degrees of freedom - resonant above-bandgap optical excitation leads to a dramatic renormalization of the THz magnon spectrum, including a near-total collapse of the magnon gap. Our analysis reveals this transformation to be consistent with a transient reduction of the exchange interaction by nearly 90% in the near-surface nanoscale region. These findings establish a pathway for light-driven, nanoscale control of AFM spin dynamics, opening opportunities for reconfigurable, high-speed magnonic and spintronic applications.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Field-theoretic Analysis of Dynamic Isotropic Percolation: Three-loop Approximation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-02 20:00 EDT
Michal Hnatič, Matej Kecer, Mikhail V. Kompaniets, Tomáš Lučivjanský, Lukáš Mižišin, Yurii G. Molotkov
The general epidemic process is a paradigmatic model in non-equilibrium statistical physics displaying a continuous phase transition between active and absorbing this http URL dynamic isotropic percolation universality class captures its universal properties, which we aim to quantitatively study by means of the field-theoretic formulation of the model augmented with a perturbative renormalization group analysis. The main purpose of this work consists in determining the critical dynamic exponent $ z$ to the three-loop approximation. This allows us to finalize the quantitative description of the dynamic isotropic percolation class to this order of perturbation theory. The calculations are performed within the dimensional regularization with the minimal subtraction scheme and actual perturbative expansions are carried out in a formally small parameter $ \epsilon$ , where $ \epsilon = 6 - d$ is a deviation from the upper critical dimension $ d_c = 6$ .
Statistical Mechanics (cond-mat.stat-mech)
Stable self-charged perovskite quantum rods for liquid laser with near-zero threshold
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Jialu Li (1), Xue Han (1), Wenjie Wang (2), Jinhui Wang (1), Tingting Zhang (2), Yuting Wu (3), Guofeng Zhang (1), Bin Li (1), Changgang Yang (1), Wenli Guo (1), Mi Zhang (1), Ruiyun Chen (1), Chengbing Qin (1), Jianyong Hu (1), Zhichun Yang (1), Shaoding Liu (2), Yue Wang (3), Yunan Gao (4), Jie Ma (1), Liantuan Xiao (1), Suotang Jia (1) ((1) State Key Laboratory of Quantum Optics Technologies and Devices, Institute of Laser Spectroscopy, Collaborative Innovation Center of Extreme Optics, Shanxi University (2) Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology (3) School of Microelectronics, College of Materials Science and Engineering, Nanjing University of Science and Technology (4) State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University)
Colloidal quantum dots (QDs) are promising optical gain materials that require further threshold reduction to realize their full potential. While QD charging theoretically reduces the threshold to zero, its effectiveness has been limited by strong Auger recombination and unstable charging. Here we theoretically reveal the optimal combination of charging number and Auger recombination to minimize the lasing threshold. Experimentally, we develop stable self-charged perovskite quantum rods (QRs) as an alternative to QDs via state engineering and Mn-doping strategy. An unprecedented two-order-of-magnitude reduction in nonradiative Auger recombination enables QRs to support a sufficient charging number of up to 6. The QR liquid lasing is then achieved with a near-zero threshold of 0.098 using quasi-continuous pumping of nanosecond pulses, which is the lowest threshold among all reported QD lasers. These achievements demonstrate the potential of the specially engineered QRs as an excellent gain media and pave the way for their prospective applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Optics (physics.optics)
Accelerating two-dimensional tensor network contractions using QR-decompositions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
Yining Zhang, Qi Yang, Philippe Corboz
Infinite projected entangled-pair states (iPEPS) provide a powerful tool for studying strongly correlated systems directly in the thermodynamic limit. A core component of the algorithm is the approximate contraction of the iPEPS, where the computational bottleneck typically lies in the singular value or eigenvalue decompositions involved in the renormalization step. This is particularly true on GPUs, where tensor contractions are substantially faster than these decompositions. Here we propose a contraction scheme for $ C_{4v}$ -symmetric tensor networks based on combining the corner transfer matrix renormalization group (CTMRG) with QR-decompositions which are substantially faster – especially on GPUs. Our approach achieves up to two orders of magnitude speedup compared to standard CTMRG and yields state-of-the-art results for the Heisenberg and $ J_1$ -$ J_2$ models in about one hour on an H100 GPU.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
6 pages, 5 figures
Signatures of three-dimensional photo-induced superconductivity in YBa$_2$Cu$3$O${6.48}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
M. Rosenberg, D. Nicoletti, M. Buzzi, A. Iudica, Y. Liu, B. Keimer, A. Cavalleri
Resonant optical excitation of apical-oxygen phonon modes in underdoped YBa$ _2$ Cu$ _3$ O$ _{6+x}$ has been shown to induce superconducting-like optical properties at temperatures far higher than the equilibrium $ T_C$ . All of the evidence collected so far has been based on the changes of the THz frequency $ c$ -axis response. In these measurements, the capacitive interlayer coupling was seen to transform into an inductive response, reminiscent of a superconducting state, an assignement that was strengthened by recent measurements of ultrafast magnetic field expulsion. Here, we report the first experimental determination of the transient in-plane optical properties. These experiements have so far been challenging because of the high in-plane equilibrium reflectivity, from which small changes in the optical response determine the transient conductivity. We observe a photo-induced in-plane optical gap $ 2\Delta\simeq30$ cm$ ^{-1}$ and a divergent imaginary conductivity, also consistent with photo-induced superconductivity. A global fit to these data suggests that in- and out-of-plane electronic properties never completely equilibrate during the dynamics.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 5 figures
Dynamical control of random telegraph noise in magnetic tunnel junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Mehrdad Elyasi, Shun Kanai, Hideo Ohno, Shunsuke Fukami, Gerrit E. W. Bauer
Rapid random telegraph noise (RTN) in magnetic tunnel junctions (MTJs) is an important figure of merit for probabilistic computing applications. However, the interactions between the macrospin and spin waves with finite wave numbers reduce the RTN attempt frequency. We theoretically show that mode-selective heating and cooling can substantially tune the RTN frequency. We propose a nonlinear cooling mechanism that accelerates the switching dynamics. We outline experimental pathways to characterize the physics of nonlinear effects on RTN and to maximize the operation speed of MTJ-based probabilistic computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Differentiating anomalous and topological Hall effects using first-order reversal curve measurements
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Gregory M. Stephen, Ryan T. Van Haren, Vinay Sharma, Lixuan Tai, Bingqian Dai, Hang Chi, Kang L. Wang, Aubrey T. Hanbicki, Adam L. Friedman
Next generation magnetic memories rely on novel magnetic phases for information storage. Novel spin textures such as skyrmions provide one possible avenue forward due to their topological protection and controllability via electric fields. However, the common signature of these spin textures, the topological Hall effect (THE), can be mimicked by other trivial effects. Competing anomalous Hall effect (AHE) components can produce a peak in the Hall voltage similar to that of the THE, making clear identification of the THE difficult. By applying the first-order reversal curve (FORC) technique to the Hall effect in candidate topological Hall systems we can clearly distinguish between the THE and AHE. This technique allows for quantitative investigation of the THE and AHE in magnetic materials and heterostructures with topologically non-trivial spin textures. We demonstrate the technique and apply it to several examples.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 4 figures
Non-Hermitian band topology in twisted bilayer graphene aligned with hexagonal boron nitride
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-02 20:00 EDT
Kamalesh Bera, Debasish Mondal, Arijit Saha, Debashree Chowdhury
Utilizing the established Bistritzer-MacDonald model for twisted bilayer graphene (tBLG), we theoretically investigate the non-Hermitian (NH) topological properties of this in the presence of non-reciprocal (NR) hopping on both layers and hexagonal boron nitride (hBN) induced mass term incorporated only on the top layer of the tBLG system. It is well known that the hBN mass term breaks the $ C_{2}$ symmetry of tBLG and gaps out the Dirac cones inducing a valley Hall insulating phase. However, when NR hopping is introduced, this system transits into a NH valley Hall insulator (NH-VHI). Our analysis reveals that, in the chiral limit, the bandwidth of the system vanishes under NH effects for a wide range of twist angles. Such range can be visibly expanded as we enhance the degree of non-Hermiticity $ (\beta)$ . At the magic angle, we observe that enhancement of $ \beta$ inflates the robustness of the gapless Dirac points, requiring a progressively larger mass term to induce a gap in the NH tBLG system. Additionally, for a fixed NH parameter, we identify a range of twist angles where gap formation is significantly obstructed. To explore the topological aspects of the NH tBLG, we analyze the direct band gap in the Moiré Brillouin zone (mBZ) and compute the Chern number for the NH system. We find that the corresponding topological phase transitions are associated with corresponding direct band gap closings in the mBZ.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
13 pages, 10 figures
Transition States Energies from Machine Learning: An Application to Reverse Water-Gas Shift on Single-Atom Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Obtaining accurate transition state (TS) energies is a bottleneck in computational screening of complex materials and reaction networks due to the high cost of TS search methods and first-principles methods such as density functional theory (DFT). Here we propose a machine learning (ML) model for predicting TS energies based on Gaussian process regression with the Wasserstein Weisfeiler-Lehman graph kernel (WWL-GPR). Applying the model to predict adsorption and TS energies for the reverse water-gas shift (RWGS) reaction on single-atom alloy (SAA) catalysts, we show that it can significantly improve the accuracy compared to traditional approaches based on scaling relations or ML models without a graph representation. Further benefitting from the low cost of model training, we train an ensemble of WWL-GPR models to obtain uncertainties through subsampling of the training data and show how these uncertainties propagate to turnover frequency (TOF) predictions through the construction of an ensemble of microkinetic models. Comparing the errors in model-based vs DFT-based TOF predictions, we show that the WWL-GPR model reduces errors by almost an order of magnitude compared to scaling relations. This demonstrates the critical impact of accurate energy predictions on catalytic activity estimation. Finally, we apply our model to screen new materials, identifying promising catalysts for RWGS. This work highlights the power of combining advanced ML techniques with DFT and microkinetic modeling for screening catalysts for complex reactions like RWGS, providing a robust framework for future catalyst design.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Unveiling competitions between carrier recombination pathways in semiconductors via mechanical damping
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-02 20:00 EDT
Mingyu Xie, Ruitian Chen, Jiaze Wu, Kaiqi Qiu, Mingqiang Li, Huicong Chen, Kai Huang, Yu Zou
The total rate of carrier recombination in semiconductors has conventionally been expressed using an additive model, r_total = \Sigma r_i , which rules out the interactions between carrier recombination pathways. Here we challenge this paradigm by demonstrating pathway competitions using our newly developed light-induced mechanical absorption spectroscopy (LIMAS), which allows us to probe genuine recombination dynamics in semiconductors via mechanical damping. We show that the total recombination rate in zinc sulfide (ZnS), a model semiconductor material, follows a multiplicative weighting model, r_total \propto \Pi r_i ^(w_i) with \Sigma w_i=1. Under both steady-state and switch-on illuminations, the weighting factors w_i for each recombination pathway-direct, trap-assisted, and sublinear-are dictated by the carrier generation mechanism: (i) interband transition favors direct recombination; (ii) single-defect level-mediated generation promotes trap-assisted recombination; (iii) generation involving multiple saturated defect levels gives rise to sublinear recombination. Upon light switch-off, localized state changes drive a dynamic evolution of w_i, altering pathway competitions. These findings reshape our fundamental understanding of carrier dynamics and provide a new strategy to optimize next-generation optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
Planckian scattering and parallel conduction channels in the iron chalcogenide superconductors FeTe$_{1-x}$Se$_x$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-02 20:00 EDT
Ralph Romero III, Hee Taek Yi, Seongshik Oh, N. P. Armitage
The remarkable linear in temperature resistivity of the cuprate superconductors, which extends in some samples from $ T_c$ to the melting temperature, remains unexplained. Although seemingly simple, this temperature dependence is incompatible with the conventional theory of metals that dictates that the scattering rate, $ 1/\tau$ , should be quadratic in temperature if electron-electron scattering dominates. Understanding the origin of this temperature dependence and its connection to superconductivity may provide the key to pick the lock of high-temperature superconductivity. Using time-domain terahertz spectroscopy (TDTS) we elucidate the low temperature conducting behavior of two FeTe$ _{1-x}$ Se$ _x$ (FTS) samples, one with almost equal amounts of Se and Te that is believed to be a topological superconductor, and one that is more overdoped. Constrained with DC resistivity, we find two conduction channels that add in parallel, a broad one in frequency with weak temperature dependence and a sharper one whose scattering rate goes as the Planckian limited rate, $ \sim kT/h$ . Through analysis of its spectral weight we show the superconducting condensate is mainly drawn from the channel that undergoes this Planckian scattering.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Single-site entanglement as a marker for quantum phase transitions at non-zero temperatures
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
Willdauany C. de Freitas Silva, Andressa R. Medeiros-Silva, Rubem Mondaini, Vivian V. França, Thereza Paiva
Entanglement has been widely investigated in condensed matter systems since they are considered good candidates for developing quantum technologies. Additionally, entanglement is a powerful tool to explore quantum phase transitions in strongly correlated systems, with the von Neumann entropy being considered a proper measure of quantum entanglement for pure bipartite systems. For lattice systems, in particular, the single-site entanglement quantifies how much information about the quantum state of the remaining sites can be obtained by a measurement at a single site. Here, we use Quantum Monte Carlo calculations to obtain the average single-site entanglement for the two-dimensional Hubbard model in different geometries, probing the effects of varying temperature and interaction strength. We find that the average single-site entanglement signals the quantum phase transitions in such systems, allowing us to identify and characterize signatures of quantum phase transitions even at finite temperatures. We also analyze the relation between entanglement and magnetic susceptibility: in all the geometries considered, we find regimes in which the quantities are linearly connected. Our findings could then guide experiments to estimate entanglement via the susceptibility.
Strongly Correlated Electrons (cond-mat.str-el)
Dynamics of Thin Lubricant Films upon Liquid Contact on Slippery Surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-02 20:00 EDT
Shivam Gupta, Bidisha Bhatt, Zhaohe Dai, Krishnacharya Khare
In recent years, slippery surfaces have attracted significant interest due to their excellent liquid-repellent properties and their potential in diverse commercial applications. Such surfaces are prepared by coating functionalized solid substrates with a thin lubricant film that prevents direct contact between a liquid and the substrate. The morphology of thin films upon liquid contact plays a central role in governing various phenomena, including the coalescence and mobility of liquid droplets, heat transfer efficiency, and the extent of lubricant depletion. However, a detailed understanding of film dynamics upon droplet contact remains limited, both from theoretical and experimental perspectives. Here, by employing principles of fluid dynamics, optics, and surface wetting, we present a comprehensive study that examines both the spatial and temporal variations of lubricant films upon contact with sessile liquid droplets and liquid bridges. Our findings reveal that the film dynamics can be categorized into three distinct stages, each significantly influenced by key system parameters: initial film thickness, three-phase contact line width, and Laplace pressure of liquids. Furthermore, we demonstrate that by optimizing these parameters, it is possible to reverse the lubricant flow in the final stage, thereby causing the liquid to partially lift off from the slippery surface.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
40 pages, 17 figures
Strange correlator and string order parameter for non-invertible symmetry protected topological phases in 1+1d
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-02 20:00 EDT
Da-Chuan Lu, Fu Xu, Yi-Zhuang You
In this paper, we construct strange correlators and string order parameters for non-invertible symmetry protected topological phases (NISPTs) in 1+1d quantum lattice spin models. The strange correlator exhibits long-range order when evaluated between two distinct NISPTs and decays exponentially otherwise. We show that strange charged operators inserted into the strange correlator are linked to the interface algebra (boundary tube algebra) and are non-trivial when all its irreducible representations have dimensions greater than one. We discuss the generalization to higher dimensions. The string order parameter is obtained by contracting the truncated symmetry operator with charge decoration operators, which are determined by the NISPT action tensors. We illustrate the above construction using the three NISPTs of $ \text{Rep}(D_8)$ and demonstrate the extraction of categorical data via tensor networks, particularly through the ZX calculus. Finally, we show that the entanglement spectrum degeneracy is determined by the irreducible representations of the interface algebra when assuming non-invertible symmetry on-site condition.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
37 pages including appendices, 1 numbered figure