CMP Journal 2025-04-10
Statistics
Nature Physics: 1
Physical Review Letters: 17
arXiv: 67
Nature Physics
Topological dynamics of rapid non-planar gaits in slithering snakes
Original Paper | Biological physics | 2025-04-09 20:00 EDT
N. Charles, R. Chelakkot, M. Gazzola, B. Young, L. Mahadevan
Snakes exhibit a wide variety of gaits, including gliding in air and sidewinding on land, which is particularly notable for its out-of-plane motion. Here we report the observation of another non-planar gait used as an escape strategy from threatening situations by juvenile anacondas (Eunectes notaeus), which we refer to as the S-start due to its shape. In this transient mode of locomotion, the snake writhes and bends out of the plane while rolling forward about its midsection without slippage. To quantify our observations, we develop a model for an active non-planar filament that interacts anisotropically with a frictional substrate. We demonstrate that locomotion is due to a propagating localized pulse of a topological quantity–the link density. A two-dimensional phase space characterized by scaled body weight and muscular torque shows that relatively light juveniles are capable of S-starts, whereas heavy adults are not, consistent with our experiments. We also show that a periodic sequence of S-starts naturally leads to a sidewinding gait.
Biological physics, Biophysics
Physical Review Letters
Operational Work Fluctuation Theorem for Open Quantum Systems
Research article | Fluctuation theorems | 2025-04-09 06:00 EDT
Konstantin Beyer and Walter T. Strunz
The classical Jarzynski equality establishes an exact relation between the stochastic work performed on a system driven out of thermal equilibrium and the free energy difference in a corresponding quasistatic process. This fluctuation theorem bears experimental relevance, as it enables the determination of the free energy difference through the measurement of externally applied work in a nonequilibrium process. In the quantum case, the Jarzynski equality only holds if the measurement procedure of the stochastic work is drastically changed: it is replaced by a so-called two-point measurement scheme that requires the knowledge of the initial and final Hamiltonian and therefore lacks the predictive power for the free energy difference that the classical Jarzynski equation is known for. Here, we propose a quantum fluctuation theorem that is valid for externally measurable quantum work determined during the driving protocol. In contrast to the two-point measurement case, the theorem also applies to open quantum systems and the scenario can be realized without knowing the system Hamiltonian. Our fluctuation theorem comes in the form of an inequality and therefore only yields bounds to the true free energy difference. The inequality is saturated in the quasiclassical case of vanishing energy coherences at the beginning and at the end of the protocol. Thus, there is a clear quantum disadvantage.
Phys. Rev. Lett. 134, 140403 (2025)
Fluctuation theorems, Quantum thermodynamics, Work theorems
Full Eigenstate Thermalization via Free Cumulants in Quantum Lattice Systems
Research article | Eigenstate thermalization | 2025-04-09 06:00 EDT
Silvia Pappalardi, Felix Fritzsch, and Tomaž Prosen
The eigenstate thermalization hypothesis (ETH) has been established as the general framework to understand quantum statistical mechanics. Only recently has the attention been paid to so-called full ETH, which accounts for higher-order correlations among matrix elements, and that can be rationalized theoretically using the language of free probability. In this work, we perform the first numerical investigation of the full ETH in physical many-body systems with local interactions by testing the decomposition of higher-order correlators into thermal free cumulants for local operators. We perform exact diagonalization on two classes of local nonintegrable (chaotic) quantum many-body systems: spin chain Hamiltonians and Floquet brickwork unitary circuits. We show that the dynamics of four-time correlation functions are encoded in fourth-order free cumulants, as predicted by ETH. Their dependence on frequency encodes the physical properties of local many-body systems and distinguishes them from structureless, rotationally invariant ensembles of random matrices.
Phys. Rev. Lett. 134, 140404 (2025)
Eigenstate thermalization, Quantum chaos, Quantum circuits, Quantum statistical mechanics, Floquet systems, Quantum spin chains, Random matrix theory, Spin chains
Resonant Excitation of Quasinormal Modes of Black Holes
Research article | Classical black holes | 2025-04-09 06:00 EDT
Hayato Motohashi
We elucidate that a distinctive resonant excitation between quasinormal modes (QNMs) of black holes emerges as a universal phenomenon at an avoided crossing near the exceptional point through high-precision numerical analysis and theory of QNMs based on the framework of non-Hermitian physics. This resonant phenomenon not only allows us to decipher a long-standing mystery concerning the peculiar behaviors of QNMs but also stands as a novel beacon for characterizing black hole spacetime geometry. Our findings pave the way for rigorous examinations of black holes and the exploration of new physics in gravity.
Phys. Rev. Lett. 134, 141401 (2025)
Classical black holes, General relativity, Gravitational waves
Wilson Loops with Lagrangians: Large-Spin Operator Product Expansion and Cusp Anomalous Dimension Dictionary
Research article | Conformal field theory | 2025-04-09 06:00 EDT
Till Bargheer, Carlos Bercini, Bruno Fernandes, Vasco Gonçalves, and Jeremy Mann
In the context of planar conformal gauge theory, we study five-point correlation functions between the interaction Lagrangian and four of the lightest single-trace, gauge-invariant scalar primaries. After performing two light-cone operator product expansions (OPEs), we express this correlator in terms of the three-point functions between two leading-twist spinning operators and the Lagrangian. For finite values of spin, we compute these structure constants in perturbation theory up to two loops in $\mathcal{N}=4$ super Yang-Mills theory. Large values of spin are captured by null polygon kinematics, where we use dualities with null polygon Wilson loops as well as factorization properties to bootstrap the universal behavior of the structure constants at all loops. We find explicit maps that relate the Lagrangian structure constants with the leading-twist anomalous dimension. From the large-spin map, we recover the cusp anomalous dimension at strong and weak coupling, including genus-one terms.
Phys. Rev. Lett. 134, 141601 (2025)
Conformal field theory, Integrability in field theory, Non-Abelian gauge theories
First Proton-Induced Cross Sections on a Stored Rare Ion Beam: Measurement of $^{118}\mathrm{Te}(\mathrm{p},\gamma )$ for Explosive Nucleosynthesis
Research article | Direct reactions | 2025-04-09 06:00 EDT
S. F. Dellmann et al.
We present the first nuclear cross-section measurements of $(\mathrm{p},\gamma )$ and (p,n) reactions on $^{118}\mathrm{Te}$ at energies relevant for the $\gamma $-process nucleosynthesis. Absolute cross-section values for center-of-mass energies of 6, 7 and 10 MeV are provided, together with a theoretical extrapolation to the Gamow window. This experiment marks the first time that direct proton-induced reactions have been measured on a radioactive ion beam at the Experimental Storage Ring (ESR) at GSI, Darmstadt. This paves the way for a large variety of measurements, delivering new constraints for explosive nucleosynthesis and for physics beyond nuclear stability.
Phys. Rev. Lett. 134, 142701 (2025)
Direct reactions, Nuclear astrophysics, Nuclear reactions, Nucleosynthesis in explosive environments, Rare & new isotopes, Radioactive beams
Multi-Axis Inertial Sensing with 2D Matter-Wave Arrays
Research article | Atom optics | 2025-04-09 06:00 EDT
K. Stolzenberg, C. Struckmann, S. Bode, R. Li, A. Herbst, V. Vollenkemper, D. Thomas, A. Rajagopalan, E. M. Rasel, N. Gaaloul, and D. Schlippert
Atom interferometery is an exquisite measurement technique sensitive to inertial forces. However, it is commonly limited to a single sensitive axis, allowing high-precision multidimensional sensing only through subsequent or postcorrected measurements. We report on a novel method for multi-axis inertial sensing based on the correlation of simultaneous light-pulse atom interferometers in 2D array arrangements of Bose-Einstein condensates (BEC). Deploying a scalable $3\times{}3$ BEC array spanning $1.6\text{ }\text{ }\mathrm{m}{\mathrm{m}}^{2}$ created using time-averaged optical potentials, we perform measurements of linear acceleration induced by gravity and simultaneously demonstrate sensitivity to angular velocity and acceleration of a rotating reference mirror, as well as gravity gradients and higher-order derivatives. Our Letter enables simple, high-precision multi-axis inertial sensing compatible with high rotation rates, e.g., for inertial navigation in dynamic environments. We finally envision further applications of our method, e.g., 3D in situ measurements and reconstruction of laser beam intensities and wave fronts.
Phys. Rev. Lett. 134, 143601 (2025)
Atom optics, Bose-Einstein condensates, Quantum optics, Atom interferometry
Reconfigurable Chiral Edge States in Synthetic Dimensions on an Integrated Photonic Chip
Research article | Integrated optics | 2025-04-09 06:00 EDT
Weiwei Liu, Xiaolong Su, Chijun Li, Cheng Zeng, Bing Wang, Yongjie Wang, Yufan Ding, Chengzhi Qin, Jinsong Xia, and Peixiang Lu
Chiral edge states are a hallmark of topological physics, and the emergence of synthetic dimensions has provided ideal platforms for investigating chiral topology while overcoming the limitations of real space. Conventional studies have primarily concentrated on symmetric chiral behaviors, limited by complex and inflexible systems. Here, we demonstrate a programmable integrated photonic platform to generate and manipulate reconfigurable chiral edge states in synthetic dimensions within a single lithium niobate microring resonator. Our system is realized by integrating independent frequency and pseudospin degrees of freedom in the dynamically modulated resonator, which features tunable artificial gauge potentials and long-range couplings. We demonstrate a variety of reconfigurable chiral behaviors in synthetic dimensions, including the realization and frustration of chiral edge states in a synthetic Hall ladder, the generation of imbalanced chiral edge currents, and the regulation of chiral behaviors among chirality, single-pseudospin enhancement, and complete suppression. This work paves the way for exploring chiral edge states in high-dimensional synthetic space on a programmable photonic chip, showing promising potential for applications in optical communications, quantum simulations, signal processing, and photonic neuromorphic computing.
Phys. Rev. Lett. 134, 143801 (2025)
Integrated optics, Nanophotonics, Non-reciprocal propagation, Synthetic gauge fields, Topological effects in photonic systems, Optical microcavities
Control of Andreev Reflection via a Single-Molecule Orbital
Research article | Andreev reflection | 2025-04-09 06:00 EDT
Lorenz Meyer, Jose L. Lado, Nicolas Néel, and Jörg Kröger
A single molecule provides a controllable connection between a normal metal and a superconductor.
Phys. Rev. Lett. 134, 146201 (2025)
Andreev reflection, Kondo effect, Transport phenomena, Molecular junctions, Scanning tunneling spectroscopy
Energy Transport in Superionic Crystals
Research article | Diffusion | 2025-04-09 06:00 EDT
Wenxiang Liu and Yanguang Zhou
In this Letter, we propose a rigorous concept based on the Onsager reciprocal theorem to describe the thermal transport behaviors in superionic crystals. Our results show that thermal energy in superionic crystals can be transferred through the conduction of atomic vibrations, the enthalpy diffusion caused by ions’ diffusion and the thermodiffusion coupling. The thermal conductivity resulting from the heat conduction pathway decreases with temperature as scatterings among vibrations and between vibrations and ions become stronger. However, the thermal conductivity due to enthalpy diffusion increases with temperature, which is because ions diffuse farther at high temperatures. The thermal conductivity owing to the thermodiffusion coupling is negligible since the chemical potential gradient under steady state is small. The apparent thermal conductivity of superionic crystals is therefore determined by the competition between these two thermal pathways, and can exhibit a diverse behavior of negative, weak, and positive temperature dependence as observed in experiments. This Letter unveils the thermal transport mechanisms in superionic crystals, which explains the long-standing and confusing thermal conductivity temperature dependence of superionic crystals.
Phys. Rev. Lett. 134, 146301 (2025)
Diffusion, Fourier’s law, Ionic transport, Thermal conductivity of fluids, Molecular dynamics
Anomalous Quantum Oscillations from Boson-Mediated Interband Scattering
Research article | Electron-phonon coupling | 2025-04-09 06:00 EDT
Léo Mangeolle and Johannes Knolle
Quantum oscillations (QOs) in metals refer to the periodic variation of thermodynamic and transport properties as a function of inverse applied magnetic field. QO frequencies are normally associated with semiclassical trajectories of Fermi surface orbits, but recent experiments challenge the canonical description. We develop a theory of composite frequency quantum oscillations (CFQOs) in two-dimensional Fermi liquids with several Fermi surfaces and interband scattering mediated by a dynamical boson, e.g., phonons or spin fluctuations. Specifically, we show that CFQOs arise from oscillations in the fermionic self-energy with anomalous frequency splitting and distinct strongly non-Lifshitz–Kosevich temperature dependences. Our theory goes beyond the framework of semiclassical Fermi surface trajectories highlighting the role of interaction effects. We provide experimental predictions and discuss the effect of nonequilibrium boson occupation in driven systems.
Phys. Rev. Lett. 134, 146502 (2025)
Electron-phonon coupling, Fermi surface, Fermions, Landau levels, Spin fluctuations, 2-dimensional systems, Metals, Lifetimes & widths, Fermi liquid theory, Quantum oscillation techniques, Shubnikov-de Haas effect, de Haas-van Alphen effect
Finite Correlation Length Scaling of Disorder Parameter at Quantum Criticality
Research article | First order phase transitions | 2025-04-09 06:00 EDT
Wen-Tao Xu and Rui-Zhen Huang
Infinite projected entangled pair states can be used to evaluate nonlocal disorder parameters capable of detecting various symmetric phases, including symmetry-protected and enriched topological phases.
Phys. Rev. Lett. 134, 146503 (2025)
First order phase transitions, Quantum criticality, Quantum entanglement, Quantum phase transitions, Second order phase transitions, Spontaneous symmetry breaking, Symmetry breaking states, Topological order, Finite-size scaling, Scaling methods, Tensor network methods, Tensor network renormalization
Nonlinear Longitudinal and Transverse Magnetoresistances due to Current-Induced Magnon Creation-Annihilation Processes
Research article | Magnetotransport | 2025-04-09 06:00 EDT
Paul Noël, Richard Schlitz, Emir Karadža, Charles-Henri Lambert, Luca Nessi, Federico Binda, and Pietro Gambardella
Charge-spin conversion phenomena, such as the spin Hall effect, allow for the excitation of magnons in a magnetic layer by passing an electric current in an adjacent nonmagnetic conductor. We demonstrate that this current-induced modification of the magnon density generates an additional nonlinear longitudinal and transverse magnetoresistance for every magnetoresistance that depends on the magnetization. Using harmonic measurements, we evidence that these magnon creation-annihilation magnetoresistances dominate the second harmonic longitudinal and transverse resistance of thin ${\mathrm{Y}}{3}{\text{Fe}}{5}{\mathrm{O}}_{12}/\mathrm{Pt}$ bilayers. Our results apply to both insulating and metallic magnetic layers, elucidating the dependence of the magnetoresistance on applied current and magnetic field for a broad variety of systems excited by spin currents.
Phys. Rev. Lett. 134, 146701 (2025)
Magnetotransport, Spin Hall magnetoresistance, Spin waves, Spin-orbit torque, Spintronics, Magnetic thin films, Hall bar, Resistivity measurements
Giant Nuclear-Electronic Spin Pumping in the Heisenberg Antiferromagnet ${\mathrm{RbMnF}}_{3}$
Research article | Magnetization dynamics | 2025-04-09 06:00 EDT
J. D. M. de Lima, D. S. Maior, E. C. Souza, D. R. Ratkovski, F. L. A. Machado, R. L. Rodríguez-Suárez, and S. M. Rezende
Collective nuclear spin excitations, called nuclear spin waves, or nuclear magnons, are enabled in strongly magnetic materials by the hyperfine coupling between the nuclear and electronic spins in an atom, and the exchange interaction between electronic spins. The investigation of nuclear spin waves garnered significant interest from theoretical and experimental researchers worldwide during the 1970s and 1980s, but gradually waned in prominence. Recently, it has been reported that the nuclear magnetic resonance in the canted antiferromagnet ${\mathrm{MnCO}}{3}$ produces spin pumping effects similar to the ones studied in ferro- and antiferromagnetic materials, bridging two quite separate worlds, the one of nuclear spin excitations and the other of spintronics. In this Letter, we report the observation of giant nuclear-electronic spin pumping effects driven by radio frequencies in the Heisenberg antiferromagnet ${\mathrm{RbMnF}}{3}$. In this material, the small values of the electronic magnon frequencies in the vicinity of the antiferromagnetic or spin-flop transition result in an enhanced frequency pulling of the nuclear magnetic resonance frequencies that produces a strong coupling between the nuclear and electronic spin degrees of freedom. This results in nuclear-electronic spin pumping signals in the Heisenberg antiferromagnet ${\mathrm{RbMnF}}{3}$ that are almost 2 orders of magnitude larger than in ${\mathrm{MnCO}}{3}$ and remain visible at temperatures nearly 10 times higher. A theory for the nuclear-electronic spin pumping process accounts well for the experimental results.
Phys. Rev. Lett. 134, 146702 (2025)
Magnetization dynamics, Magnons, Spin pumping, Spin waves, Spintronics, Antiferromagnets, Nuclear magnetic resonance, Sputtering
Crisis in Time-Dependent Dynamical Systems
Research article | Chaos | 2025-04-09 06:00 EDT
Simona Olmi and Antonio Politi
Many dynamical systems operate in a fluctuating environment. However, even in low-dimensional setups, transitions and bifurcations have not yet been fully understood. In this Letter we focus on crises, a sudden flooding of the phase space due to the crossing of the boundary of the basin of attraction. We find that crises occur also in nonautonomous systems although the underlying mechanism is more complex. We show that in the vicinity of the transition, the escape probability scales as $\mathrm{exp}[- \alpha (\mathrm{ln}\delta {)}^{2}]$, where $\delta $ is the distance from the critical point, while $\alpha $ is a model-dependent parameter. This prediction is tested and verified in a few different systems, including the Kuramoto model with inertia, where the crisis controls the loss of stability of a chimera state.
Phys. Rev. Lett. 134, 147202 (2025)
Chaos, Collective dynamics, Coupled oscillators, Dynamics of networks, Chaotic systems, Dynamical systems, High dimensional systems, Multiple time scale dynamics
Real-Time Visualization of Single Polymer Conformational Change in the Bulk State during Mechanical Deformation
Research article | Mechanical deformation | 2025-04-09 06:00 EDT
Ruiqi Xiao, Subhadeep Pal, Christopher P. Rademacher, Jie Chen, Qifeng Wang, Wei Chen, Kenneth R. Shull, Sinan Keten, and Muzhou Wang
Single-molecule localization microscopy and fluorescent labeling are employed to observe the conformation and orientation of single polymers within a bulk material, surpassing the diffraction limit of traditional optical microscopy.
Phys. Rev. Lett. 134, 148101 (2025)
Mechanical deformation, Polymer conformation changes, Optical microscopy
Hyperelastic Swelling of Stiff Hydrogels
Research article | Rheology | 2025-04-09 06:00 EDT
Jing Wang and Justin C. Burton
Hydrogels are swollen polymer networks where elastic deformation is coupled to nanoscale fluid flow. As a consequence, hydrogels can withstand large strains and exhibit nonlinear, hyperelastic properties. Previous studies have shown that low-modulus hydrogels and semiflexible biopolymer networks universally contract when sheared on timescales much longer than the poroelastic relaxation timescale. Using rheological and tribological measurements, we find that stiff polyacrylamide and polyacrylic acid hydrogels, with moduli of order $\sim 10–100\text{ }\text{ }\mathrm{kPa}$, exclusively swell (dilate) when sheared. Poroelastic relaxation was examined using strain-controlled compression, indicating a volumetric diffusion constant of order ${10}^{- 9}\text{ }{\mathrm{m}}^{2}/\mathrm{s}$. Upon shearing, we observed an increase in normal stress that varied quadratically with shear strain, which persisted for hours. Moreover, we show that this dilatant behavior manifests as swelling during tribological sliding, imbibing the hydrogel with fluid. We suggest that this inherent, hyperelastic dilatancy is an important feature in all stiff hydrogels, and may explain rehydration and mechanical rejuvenation in biological tissues such as cartilage.
Phys. Rev. Lett. 134, 148203 (2025)
Rheology, Tribology, Hydrogels, Polymer gels
Hierarchy of Chaotic Dynamics in Random Modular Networks
Research article | Chaos | 2025-04-09 06:00 EDT
Łukasz Kuśmierz, Ulises Pereira-Obilinovic, Zhixin Lu, Dana Mastrovito, and Stefan Mihalas
The interplay between microscopic and macroscopic dynamics in a brain-like network enhances the robustness of a state that optimizes the network’s performance.
Phys. Rev. Lett. 134, 148402 (2025)
Chaos, Neuronal dynamics, Neuroscience, neural computation & artificial intelligence, Artificial neural networks, Biological neural networks, Brain, Chaotic systems, High dimensional systems, Chaos & nonlinear dynamics, Mean field theory, Statistical methods
arXiv
Inverse Single-sided Magnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
A single-sided magnet generates a magnetic field on only one side while canceling it on the opposite side, a feature that has enabled diverse applications in both fundamental science and engineering. Here, we propose the {\it inverse} single-sided magnet: a non-ferromagnetic system that selectively attracts either the north or south pole of a ferromagnet while remaining unresponsive to the opposite pole. We demonstrate that such behavior can arise in microscopic octupolar magnets. To illustrate this, we analyze two minimal models: a coplanar magnetic structure with 120-degree ordering and a collinear magnetic structure with site-dependent anisotropy. In both cases, we find that the magnetization response is nonreciprocal with respect to the sign of the applied magnetic field. Notably, in the latter model, the system exhibits strong magnetization in one field direction and negligible response in the opposite direction. This diode-like behavior for magnetic fields suggests that inverse single-sided magnets could play a pivotal role in controlling magnetic interference, with potential impact comparable to conventional single-sided magnets.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
5 pages, 3 figures
Performance optimization of Nernst-based thermionic engines
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Wei Yan, Minglong Lv, Ousi Pan, Zhimin Yang, Jincan Chen, Shanhe Su
In this paper, we examine the power and efficiency of the thermionic device utilizing the Nernst effect, with a specific focus on its potential application as an engine. The device operates by utilizing the vertical heat current to generate a horizontal particle current against the chemical potential. By considering the influence of a strong magnetic field, we derive analytical expressions for the current and heat flux. These expressions are dependent on the temperature and chemical potential of heat reservoirs, providing valuable insights into the device performance. The impact of driving temperatures on the performance of the thermionic engine has been assessed through numerical analysis. The research findings will guide the experimental design of Nernst-based thermionic engines.
Statistical Mechanics (cond-mat.stat-mech)
Elastic anisotropy and Surface Acoustic Wave propagation in CoFeB/Au multilayers: influence of thickness and light penetration depth
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
A. V. Achuthan, S. Janardhanan, P. Kuswik, A. Trzaskowska
Surface acoustic waves in multilayered nanostructures represent a critical frontier in understanding material behavior at the nanoscale, with profound implications for emerging acoustic and spintronic technologies. In this study, we investigate the influence of the magnetic layer thickness on the propagation of surface acoustic waves in CoFeB based multilayers. Two approaches to effective medium modelling are considered: one treating the entire multilayer as a homogeneous medium and another focusing on the region affected by light penetration. The elastic properties of the system are analyzed using Brillouin light scattering and numerical modelling, with a particular emphasis on the anisotropy of Young s modulus and its dependence on CoFeB thickness. The results reveal a significant variation in surface acoustic wave velocity and elastic anisotropy as a function of the multilayer configuration, highlighting the role of the penetration depth in effective medium approximations. These findings provide valuable insights into the tunability of acoustic and spin-wave frequencies through structural modifications, which is crucial for the development of high-performance resonators, surface acoustic wave filters, and spin-wave-based information processing devices.
Materials Science (cond-mat.mtrl-sci)
Self-organization, detailed balance, and stress-structure correlations in 2D granular dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Raphael Blumenfeld, Takashi Matsushima, Jie Zhang
We argue that a number of recent experimental and numerical observations point to an ongoing cooperative stress-structure self-organisation (SO) in quasi-static granular dynamics. These observations include: a) detail-insensitive collapses of certain quantities; b) correlations between stress and structure and evidence of entropy-stability competition in settled packings, which cast doubt on most linear stress theories of granular materials; c) detailed balanced steady states, which seem contradictory to the common belief that only systems in thermal equilibrium satisfy detailed balance, but are not, as we explain. We then propose a new statistical mechanical formulation that takes into account the cooperative SO.
Statistical Mechanics (cond-mat.stat-mech)
4 pages, 1 figure
Quantum hydrodynamics of a polariton fluid: pure energy relaxation terms
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
D. A. Saltykova, A. V. Yulin, I. A. Shelykh
Cavity polaritons, hybrid half-light half-matter excitations in quantum microcavities in the strong-coupling regime demonstrate clear signatures of quantum collective behavior, such as analogues of BEC and superfluidity at surprisingly high temperatures. The analysis of the formation of these states demands an account of the relaxation processes in the system. Although there are well-established approaches for the description of some of them, such as finite lifetime polariton, an external optical pump, and coupling with an incoherent excitonic reservoir, the treatment of pure energy relaxation in a polariton fluid still remains a puzzle. Here, based on the quantum hydrodynamics approach, we derive the corresponding equations where the energy relaxation term appears naturally. We analyze in detail how it affects the dynamics of polariton droplets and the dispersion of elementary excitations of a uniform polariton condensate. Although we focus on the case of cavity polaritons, our approach can be applied to other cases of bosonic condensates, where the processes of energy relaxation play an important role.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Pattern Formation and Solitons (nlin.PS), Quantum Physics (quant-ph)
6 pages + 4 pages of Supplementary Materials
On the interfacial properties of hydroquinone: realistic and coarse-grained molecular models from computer simulation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-10 20:00 EDT
M. J. Torrejón, B. Rodríguez García, J. Algaba, J. M. Olmos, M. Peréz-Rodríguez, J. M. Míguez, A. Mejía, M. M. Piñeiro, F. J. Blas
In this work, we determine the vapor-liquid (VL) coexistence and interfacial properties of the hydroquinone (HQ) pure system from $ NVT$ molecular dynamics simulations. We employ the direct coexistence technique to put in contact both phases in the same simulation box and generate the VL interface. Five different models have been tested to describe the HQ molecule in order to assess the performance of different approaches. The first two models are based on the Transferable Parameters Potentials for Phase Equilibria (TraPPE) force field. The first TraPPE model is the original one based on an all-atoms approach (TraPPE-AA). The second TraPPE model is proposed for the first time in this work and is based on a united-atoms approach (TraPPE-UA) where the –CH groups from the aromatic ring are modeled as a single interaction site. We also use two HQ models based on the Optimized Potentials for Liquid Simulations (OPLS) force fields. Both OPLS models have already been reported in the literature, but this is the first time that are used to describe VLE and interfacial behavior. In addition, we propose a new Coarse grain (CG) HQ model based on the Statistical Associating Fluid Theory (SAFT) framework. We determine density profiles, coexistence densities, vapor pressure, interfacial thicknesses, and interfacial tensions as obtained from the $ NVT$ simulations with the five different models. We explore the VL behavior of pure HQ system from 500 to $ 750,\text{K}$ . Remarkably good agreement has been found between the simulation results obtained by the TraPPE-AA, CG, and both OPLS models.
Soft Condensed Matter (cond-mat.soft)
12 pages, 10 figures, 3 tables
Optical properties of TiS$_3$ as a novel thin film for single-junction and tandem solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Cesar E. P. Villegas, Enesio Marinho Jr, A. C. Dias, Pedro Venezuela, Alexandre R. Rocha
Sub-micrometer thin films are promising platforms for emerging flexible photovoltaic devices. Although the current market already produces efficient solar cells, the average wafer thickness of these devices remains far from the sub-micrometer scale, making them susceptible to cracking under bending stress and thus precluding their use in flexible device applications. Due to its earth abundance, non-toxicity, and low elastic modulus, titanium trisulfide (TiS$ _3$ ) has emerged as a promising alternative for flexible device applications. Here, using excited-state density functional calculations combined with the transfer matrix approach, we perform an optical analysis and assess the efficiency of a prototype photovoltaic device based on sub-micrometer TiS$ _3$ thin films. Using optical constants obtained from our first-principles calculations, we evaluate the photovoltaic response of a single-junction device in the radiative limit, finding that a 140-nm-thick active layer achieves a maximum power conversion efficiency of approximately 22%. Additionally, we investigate tandem solar cells that incorporate TiS$ _3$ into perovskite thin films, and find that the lower and upper power conversion efficiencies range from approximately 18% to 33%. Overall, our results suggest great potential for using TiS$ _3$ thin films as an active layer in the design of highly efficient flexible solar cells.
Materials Science (cond-mat.mtrl-sci)
Resistance hysteresis in twisted bilayer graphene: Intrinsic versus extrinsic effects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Ranit Dutta, Ayan Ghosh, Kenji Watanabe, Takashi Taniguchi, Anindya Das
Hysteresis in resistance under magnetic field sweeps is a key signature for identifying magnetism in twisted bilayer graphene and similar systems. However, such sweeps can induce extrinsic thermal effects, complicating interpretations. Distinguishing intrinsic magnetic ordering from extrinsic thermal influences is crucial. In this study, we report hysteresis in the longitudinal resistance ($ (R_{xx}$ )) of a near magic-angle twisted bilayer graphene (TBG) sample under an in-plane magnetic field ($ (B_{||}$ )). The hysteresis phase appears at the edge of the superconducting dome, diminishes deep within the superconducting regime, and reemerges near the superconducting critical temperature ($ (T \sim T_c$ )). The hysteresis magnitude and coercive fields strongly depend on the magnetic field sweep rate ($ (dB/dt)$ ) and exhibit transient relaxation in time-series measurements. Notably, similar hysteresis behavior was observed in the temperature profile of the sample stage, measured using a calibrated temperature sensor under analogous magnetic field cycles, suggesting extrinsic thermal origins rather than intrinsic magnetic ordering. These findings underscore the importance of carefully distinguishing intrinsic and extrinsic effects in resistance hysteresis observed in mesoscopic van der Waals systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Polaron-induced modifications in the linear and nonlinear optical properties of graphene under electric and magnetic fields
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
S. Mounbou, S. I. Fewo, L. A. Ribeiro Jr, C. Kenfack-Sadem
Polarons are the primary charge carriers in organic materials. A deep understanding of their properties can open channels for novel optoelectronic applications. By applying electric and magnetic fields, we investigate the influence of polaron interactions on the linear and nonlinear optical properties of a graphene monolayer between a substrate and air. Using the density matrix approach, we derive the linear and nonlinear optical absorption coefficients and the relative refractive index by incorporating the zero-energy level. Our numerical results reveal that the polaron effect and the magnetic field induce shifts in the peak positions of the optical absorption coefficients and refractive index. Moreover, while the presence of electric and magnetic fields significantly alters the amplitude of the absorption coefficients, only the magnetic field affects the refractive index amplitude. Additionally, we find that the magnetic field amplifies the influence of surface optical phonons on the optical properties of graphene. These findings provide deeper insights into the optical behavior of graphene in external fields, which could be relevant for optoelectronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
31 pages
How to Make a Pristine Tellurium Atomic Helix
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Tellurium atomic helices are currently attracting increasing attention. However, to date individual tellurium atomic helices have only been grown encapsulated in host materials. A bare free-standing tellurium atomic helix has yet to be realized experimentally despite the fundamental interest of these systems. Here DFT-based simulations are presented that show that a pristine tellurium atomic helix can be drawn from a tellurium crystal with the help of a gold STM tip, paving the way to a better understanding of tellurium atomic helices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
2 pages, 2 figures
Quantized Artificial Neural Networks Implemented with Spintronic Stochastic Computing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Saadi Sabyasachi, Walid Al Misba, Yixin Shao, Pedram Khalili Amiri, Jayasimha Atulasimha
An Artificial Neural Network (ANN) inference involves matrix vector multiplications that require a very large number of multiply and accumulate operations, resulting in high energy cost and large device footprint. Stochastic computing (SC) offers a less resource-intensive ANN implementation and can be realized through stochastic-magnetic tunnel junctions (s-MTJ) that generate random numbers, where the energy barrier to switch between the up and down states is designed to be small. While s-MTJs have previously been used to implement SC-ANNs, these studies have been limited to architectures with continuously varying (analog) weights. We study the use of SC for matrix vector multiplication with quantized synaptic weights and outputs. We show that a quantized SC-ANN, implemented by using experimentally obtained s-MTJ bitstreams and using a limited number of discrete quantized states for both weights and hidden layer outputs in an ANN, can effectively reduce latency and energy consumption in SC compared to an analog implementation, while largely preserving accuracy. We implemented quantization with 5 and 11 quantized states, along with SC configured with stochastic bitstream lengths of 100 to 500 on neural networks with one and three hidden layers. Inference was performed on the MNIST dataset for both training with SC and without SC. Training with SC provided better accuracy for all cases. For the shortest bitstream of 100 bits, the highest accuracies were 92% for one hidden layer and over 96% for three hidden layers. The overall system attained its peak accuracy of 96.82% using a 400-bit stochastic bitstream with three hidden layers and demonstrated 9X improvement in latency to implement neuron activations and 2.6X improvement in energy consumption using the quantized SC approach compared to a similar s-MTJ based ANN architecture without quantization.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
High critical current densities of body-centered cubic high-entropy alloy superconductors: recent research progress
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Jiro Kitagawa, Yoshikazu Mizuguchi, Terukazu Nishizaki
High-entropy alloy (HEA) superconductors have garnered significant attention due to their unique characteristics, such as robust superconductivity under extremely high pressure and irradiation, the cocktail effect, and the enhancement of the upper critical field. A high critical current density is another noteworthy feature observed in HEAs. Several body-centered cubic (bcc) HEAs have exhibited critical current densities comparable to those of Nb-Ti superconducting alloys. Such HEAs hold potential for applications as multifunctional superconducting wires, a capability rarely achieved in conventional alloys. In this context, we review recent advancements in research on critical current densities in bcc HEA superconductors, including Ta$ _{1/6}$ Nb$ _{2/6}$ Hf$ _{1/6}$ Zr$ _{1/6}$ Ti$ _{1/6}$ , (TaNb)$ _{0.7}$ (HfZrTi)$ _{0.5}$ , NbScTiZr, and others. Comparative analyses among these HEAs reveal that both eutectic microstructures, which accompany lattice strain, and nanosized precipitates play pivotal roles in achieving elevated critical current densities across wide magnetic field ranges. Furthermore, we propose several future directions for research. These include elucidating the origin of lattice strain, exploring more fine eutectic microstructures, artificially introducing nanoscale pinning sites, improving the superconducting critical temperature, and investigating the mechanical properties of these materials.
Superconductivity (cond-mat.supr-con)
to appear in The European Physical Journal B
Advances in quantum defect embedding theory
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Siyuan Chen, Victor Wen-zhe Yu, Yu Jin, Marco Govoni, Giulia Galli
Quantum defect embedding theory (QDET) is a many-body embedding method designed to describe condensed systems with strongly correlated electrons localized within a given region of space, for example spin defects in semiconductors and insulators. Although the QDET approach has been successful in predicting the electronic properties of several point defects, several limitations of the method remain. In this work, we propose multiple advances to the QDET formalism. We derive a double-counting correction that consistently treats the frequency dependence of the screened Coulomb interaction, and we illustrate the effect of including unoccupied orbitals in the active space. In addition, we propose a method to describe hybridization effects between the active space and the environment, and we compare the results of several impurity solvers, providing further insights into improving the reliability and applicability of the method. We present results for defects in diamond and for molecular qubits, including a detailed comparison with experiments.
Materials Science (cond-mat.mtrl-sci)
40 pages, 6 figures
Dynamics of Conducting Ferroelectric Domain Walls
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Carson Carroll, W. A. Atkinson
We report on the dynamics of a conducting domain wall under applied dc and ac voltages. These dynamics are modeled for a thin film that hosts an ideal charged domain wall via a combination of time-dependent Ginzburg-Landau equations for the polarization, the Schrödinger equation for the electron gas, and Poisson’s equation for the electrostatic potential. The electron dynamics are treated within a Born-Oppenheimer approximation. We find that the electron gas introduces an additional degree of freedom, beyond polarization relaxation, that modifies the dynamical response of the domain wall. While marginally relevant for the dc response, the electron dynamics have a pronounced effect on the film’s ac dielectric function. The dielectric function has an intrinsic contribution, due to the bulk susceptibility of the film, and an extrinsic contribution due to the domain-wall displacement. The elecron gas affects the dielectric function by changing both the amplitude and phase of the displacement.
Materials Science (cond-mat.mtrl-sci)
Identifying Universal Spin Excitations in Spin-1/2 Kagome Quantum Spin Liquid Materials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
Aaron T. Breidenbach, Arthur C. Campello, Jiajia Wen, Hong-Chen Jiang, Daniel M. Pajerowski, Rebecca W. Smaha, Young S. Lee
A quantum spin liquid (QSL) is an exotic quantum state of matter characterized by fluctuating spins which may exhibit long-range entanglement. Among the possible host candidates for a QSL ground state, the $ S$ =1/2 kagome lattice antiferromagnet is particularly promising. Using high resolution inelastic neutron scattering measurements on Zn-barlowite (Zn$ _\mathrm{x}$ Cu$ _\mathrm{4-x}$ (OD)$ _\mathrm{6}$ FBr, $ x\simeq 0.80$ ), we measure a spin excitation spectrum consistent with a QSL ground state. Continuum scattering above $ \sim$ 1 meV matches that of herbertsmithite (Zn$ _\mathrm{x}$ Cu$ _\mathrm{4-x}$ (OD)$ _6$ Cl$ _2$ , $ x\simeq 0.85$ ), another prominent kagome QSL material, indicating universal spinon excitations. A detailed analysis of the spin-spin correlations, compared with density matrix renormalization group calculations, further indicate a QSL ground state for the physically relevant Hamiltonian parameters. The measured spectra in Zn-barlowite are consistent with gapped behavior with a gap size $ \Delta = 1.1(2)$ meV. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results clarify the behavior that is universal within this important family of QSL candidate materials.
Strongly Correlated Electrons (cond-mat.str-el)
A critical theory for solidification of a liquid Fermi liquid
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
We give a simple description of a zero-temperature phase transition between a liquid metal and a solid. The critical point has a Fermi surface as well as a Bose surface, a sphere in momentum space of gapless bosonic excitations. We find a fixed point of the renormalization group governing such a non-Fermi liquid, using an expansion in the codimension of both the Fermi and Bose surfaces. We comment on the nature of the solid phase and possible physical realizations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
5 + 25 pages, lots of intersecting circles
Exceptionally large winding number of a finite-size topological superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Satoshi Ikegaya, Shingo Kobayashi, Yasuhiro Asano
We study finite-size-induced topological phenomena in unconventional superconductors. Specifically, we focus on a thin film with a persistent spin texture, fabricated on a high-$ T_{\text{c}}$ cuprate $ d_{xy}$ -wave superconductors. In two-dimensional $ d_{xy}$ -wave superconductors, flat-band Andreev bound states appear at the edges. As the system narrows, these bound states acquire an energy gap due to finite-size hybridization and spin-orbit coupling of the persistent spin texture. This induced gap gives rise to the emergence of a topological phase, characterized by an exceptionally large one-dimensional winding number that scales with the film width. We demonstrate the appearance of highly degenerate zero-energy states, leading to anomalous perfect charge transport in dirty superconducting junctions. These findings provide a promising platform for exploring fascinating topological superconducting phases driven by gapped Andreev bound states.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Weyl Phonons: The connection of topology and chirality
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Tiantian Zhang, Shuichi Murakami, Hu Miao
Topology and chirality of fermionic quasiparticles have enabled exciting discoveries, including quantum anomalous Hall liquids and topological superconductivity. Recently, topological and chiral phonons emerge as new and fast-evolving research directions. While these concepts are separately developed, they are intimately connected in the context of Weyl phonons. The couplings between chiral and topological phonons with various electronic and magnetic quasiparticles are predicted to give rise to new quantum states and giant magnetism with fundamental and applicational interests, ranging from quantum information science to dark matter detectors.
Materials Science (cond-mat.mtrl-sci)
To appear in Nature Communications as a COMMENT
Artificial Spin Ice: A Tutorial on Design and Control of Geometry, Microstate, Magnon Dynamics & Neuromorphic Computing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Rawnak Sultana, Amrit Kumar Mondal, Vinayak Shantaram Bhat, Kilian Stenning, Yue Li, Daan M. Arroo, Aastha Vasdev, Margaret R. McCarter, Lance E. De Long, J. Todd Hastings, Jack C. Gartside, M. Benjamin Jungfleisch
Artificial spin ice, arrays of strongly interacting nanomagnets, are complex magnetic systems with many emergent properties, rich microstate spaces, intrinsic physical memory, high-frequency dynamics in the GHz range and compatibility with a broad range of measurement approaches. This tutorial article aims to provide the foundational knowledge needed to understand, design, develop, and improve the dynamic properties of artificial spin ice (ASI). Special emphasis is placed on introducing the theory of micromagnetics, which describes the complex dynamics within these systems, along with their design, fabrication methods, and standard measurement and control techniques. The article begins with a review of the historical background, introducing the underlying physical phenomena and interactions that govern artificial spin ice. We then explore standard experimental techniques used to prepare the microstate space of the nanomagnetic array and to characterize magnetization dynamics, both in artificial spin ice and more broadly in ferromagnetic materials. Finally, we introduce the basics of neuromorphic computing applied to the case of artificial spin ice systems with goal to help researchers new to the field grasp these exciting new developments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)
Giant Rashba splitting in PtTe/PtTe$_2$ heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Runfa Feng, Yang Zhang, Jiaheng Li, Qian Li, Changhua Bao, Hongyun Zhang, Wanying Chen, Xiao Tang, Ken Yaegashi, Katsuaki Sugawara, Takafumi Sato, Wenhui Duan, Pu Yu, Shuyun Zhou
Achieving a large spin splitting is highly desirable for spintronic devices, which often requires breaking of the inversion symmetry. However, many atomically thin films are centrosymmetric, making them unsuitable for spintronic applications. Here, we report a strategy to achieve inversion symmetry breaking from a centrosymmetric transition metal dichalcogenide (TMDC) bilayer PtTe$ _2$ , leading to a giant Rashba spin splitting. Specifically, the thermal annealing turns one layer of PtTe$ _2$ sample into a transition metal monochalcogenide (TMMC) PtTe through Te extraction, thus forming PtTe/PtTe$ _2$ heterostructure with inversion symmetry breaking. In the naturally-formed PtTe/PtTe$ 2$ heterostructure, we observe a giant Rashba spin splitting with Rashba coefficient of $ \alpha{R}$ = 1.8 eV$ \cdot$ Å$ , as revealed by spin- and angle-resolved photoemission spectroscopy measurements. Our work demonstrates a convenient and effective pathway for achieving pronounced Rashba splitting in centrosymmetric TMDC thin films by creating TMMC/TMDC heterostructure, thereby extending their potential applications to spintronics.
Materials Science (cond-mat.mtrl-sci)
Nat. Commun. 16, 2667 (2025)
Resistivity measurement for non-magnetic materials using high-order resonance mode of mfm-cantilever oscillation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Kazuma Okamoto, Takumi Imura, Satoshi Abo, Fujio Wakaya, Katsuhisa Murakami, Masayoshi Nagao
A method to measure the electrical resistivity of materials using magnetic-force microscopy (MFM) is discussed, where MFM detects the magnetic field caused by the tip-oscillation-induced eddy current. To achieve high sensitivity, a high cantilever oscillation frequency is preferable, because it induces large eddy currents in the material. Higher-order resonance modes of the cantilever oscillation leads to higher frequency. To discuss such high-order-mode oscillation, a differential equation governing MFM cantilever oscillation in the high-order resonance mode is formulated, and an analytical solution of the phase difference is obtained. The result shows that the phase difference decreases at higher modes, because the effective spring constant increases faster than the force from the eddy current.
Materials Science (cond-mat.mtrl-sci), Instrumentation and Detectors (physics.ins-det)
12 pages, 6 figures, 2024MNC, published in JJAP
Japanese Journal of Applied Physics 64, 04SP24 (2025)
Time-local stochastic equation of motion for solid ionic electrolytes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Aleksandr Rodin, Ben Andrew Olsen, Andrey Ustyuzhanin, Artem Maevskiy
Numerical studies of ionic motion through solid electrolytes commonly involve static nudged-elastic band (NEB) methods or costly \emph{ab initio} molecular dynamics (AIMD). Building on a time-local model of current carrier-electrolyte interaction and incorporating thermal motion, we introduce an approach that is intermediate between the two well-established methodologies by treating the electrolyte as an effective medium that interacts with the mobile particle. Through this coupling, the thermally vibrating electrolyte imparts energy to the charge carriers while also absorbing energy from them due to its own finite elasticity. Using a simple model system, we validate our approach through a series of numerical simulations. Our methodology reproduces both dissipative and diffusive behavior, and helps link microscopic system parameters to measurable macroscopic properties.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 7 figures
Localization of deformation in the central hub of hub-and-spoke kirigami
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-10 20:00 EDT
Jason Barckicke, Lucie Domino, Qun Zhang, Mingchao Liu, Dominic Vella
A recent approach to the design of flexible electronic devices consists of cutting a two-dimensional sheet to form a central hub connected to several tapered spokes', resembling the hub-and-spoke of a bicycle wheel. When radially compressed, the resulting cut sheet buckles out-of-plane forming a structure whose three-dimensional shape can be chosen by designing the tapering of the spokes. While the deformation of the spokes in this hub-and-spoke’ kirigami are approximately cylindrical (i.e.~zero Gaussian curvature and hence small elastic strain), this is not the case in the central hub. The central hub is deformed radially because of continuity with the spokes but, because of its own circular symmetry, it must develop Gaussian curvature, and hence strain. In this article we quantify this strain, focussing in particular on its magnitude and its location. We find that the strain is localized in a boundary layer near the edge of the hub region, whose size is controlled by the moment applied on it by the deformed spokes. We discuss the implications of our results for avoiding material failure in flexible-electronic devices.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Entropy Production in Non-Gaussian Active Matter: A Unified Fluctuation Theorem and Deep Learning Framework
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Yuanfei Huang, Chengyu Liu, Bing Miao, Xiang Zhou
We present a general framework for deriving entropy production rates in active matter systems driven by non-Gaussian active fluctuations. Employing the probability flow equivalence technique, we rigorously derive an entropy production decomposition formula and demonstrate that the entropy production, $ \Delta s_\mathrm{tot}$ , satisfies the integral fluctuation theorem $ \langle \exp[ -\Delta s_\mathrm{tot} + B_\mathrm{act}] \rangle = 1$ and the generalized second law of thermodynamics $ \langle \Delta s_\mathrm{tot}\rangle \geq\langle B_\mathrm{act}\rangle$ , where $ B_\mathrm{act}$ is a path-dependent random variable associated with the active fluctuations. Our result holds generally for arbitrary initial conditions, encompassing both steady-state and transient finite-time regimes. In the limiting case where active fluctuations are absent (i.e., $ B_\mathrm{act} \equiv 0$ ), the theorem reduces to the well-established results in stochastic thermodynamics. Building on the theoretical foundation, we propose a deep learning-based methodology to efficiently compute the entropy production, utilizing the Lévy score function we proposed. To illustrate the validity of this approach, we apply it to two representative systems: a Brownian particle in a periodic active bath and an active polymer system consisting of an active Brownian particle cross-linker interacting with passive Brownian beads. Our results provide a unified framework for analyzing entropy production in active matter systems while offering practical computational tools for investigating complex nonequilibrium behaviors.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
Two-Axis planar Hall magnetic field sensors with sub nanoTesla resolution
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
Proloy Taran Das, Hariharan Nhalil, Vladislav Mor, Moty Schultz, Nir Hasidim, Asaf Grosz, Lior Klein
Planar Hall effect (PHE) magnetic sensors are attractive for various applications where the field resolution is required in the range of sub-nano Tesla or in Pico Tesla. Here we present a detailed noise study of the PHE sensors consisting of two or three intersecting ellipses. It can be used to measure two axes of the magnetic field in the sensor plane in particular along the two perpendicular easy axes in the overlapping region for two intersecting ellipses and three easy axes at an angle of 60 degrees for three crossing ellipses. Thus, for each remanent magnetic state in the overlap area, the sensor can measure the vector component of the magnetic field perpendicular to the direction of the remanent magnetization. The two field components are measured with a field resolution less than 200 pT/sqrt(Hz) at 10 Hz and 350 pT/sqrt(Hz) at 1 Hz in the same region, while maintaining a similar size and noise level of a single-axis sensor. Furthermore, we discuss here the possible route for future improvement of the field resolution
Strongly Correlated Electrons (cond-mat.str-el)
4 pages, 4 figures
IEEE Transactions on Magnetics, vol. 60, no. 9, pp. 1-4, Sept. 2024, Art no. 4000404
Current-Enabled Optical Conductivity of Collective Modes in Unconventional Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Gerrit Niederhoff, Ryusei Kataoka, Kazuaki Takasan, Naoto Tsuji
We theoretically investigate the current-enabled linear optical conductivity of collective modes in superconductors with unconventional pairing symmetries. After deriving general formulas for the optical conductivity of a superconductor featuring multiple pairing channels and bands using the path integral formalism, we apply these formulas to several models. Using a model of competing s- and d-wave pairing interactions, we find that several known collective modes generate peaks in the optical conductivity upon injection of a supercurrent. This includes single- and multiband versions of Bardasis-Schrieffer modes, mixed-symmetry Bardasis-Schrieffer modes, and Leggett modes. Using a model for interband p-wave superconductivity with Rashba spin-orbit coupling, we find that in such a system Bardasis-Schrieffer modes are optically active even without introducing a supercurrent. In a p+ip chiral ground state, these modes turn out to produce peaks in the longitudinal and transverse optical conductivity. Other collective modes belonging to the chiral p+ip order parameter turn out to be unaffected by the spin-orbit coupling but contribute to the optical response when a supercurrent is introduced. These results promise new avenues for the observation of collective modes in a variety of superconducting systems, including multiband superconductors and superconductors that feature multiple pairing channels or multi-component order parameters, such as chiral p- or d-wave superconductors.
Superconductivity (cond-mat.supr-con)
Identifying the Nano Interface Through Phase
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
The quantum dots (QD) interface in solution can play significant roles in electron transfer dynamics for quantum dots-sensitized solar cells and different biological, environmental, and industrial systems. Here, we predict an avenue to identify the contribution of the quantum dots interface created static electric field on the nonlinear optical response (NLO) due to four-wave mixing (FWM), especially for the nanoparticles where surface contribution is high. We implement a way to disentangle the FWM response in QDs originating from the three incoming oscillating laser fields (NLOoscillating) and a contribution (NLOstatic) arising from the three oscillating laser fields and the static electric field caused by the interface. Advanced two-dimensional electronic spectroscopy (2DES) employs phase-resolved heterodyne techniques where FWM response is measured in a particular phase-matched direction, and the response is distinctively phase sensitive. Theoretical analysis shows alteration in the interface can introduce phase variation in the NLOstatic signal, resulting in a distinct change in the 2D-spectra. Our studies establish a range of ionic strength, which can be important to untwine the usual NLO signal (NLOoscillating) from the NLO (NLOstatic) contributed by the interface of quantum dots. This analysis may open up the possibility to study the different kinds of dynamics occurring specifically in the interface and also will pave the path towards different ion interactions through phase change in 2D spectra, and enormous scope will be employing deep learning-assisted phase recognition.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Journal of Physical Chemistry C September 5 2024 Volume 128, Issue 35 Pages 14569-14860
Defects in Silicon Carbide as Quantum Qubits: Recent Advances in Defect Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
This review provides an overview of defects in silicon carbide (SiC) with potential applications as quantum qubits. It begins with a brief introduction to quantum qubits and existing qubit platforms, outlining the essential criteria a defect must meet to function as a viable qubit. The focus then shifts to the most promising defects in SiC, notably the silicon vacancy (VSi) and divacancy (VC-VSi). A key challenge in utilizing these defects for quantum applications is their precise and controllable creation. Various fabrication techniques, including irradiation, ion implantation, femtosecond laser processing, and focused ion beam methods, have been explored to create these defects. Designed as a beginner-friendly resource, this review aims to support early-career experimental researchers entering the field of SiC-related quantum qubits. Providing an introduction to defect-based qubits in SiC offers valuable insights into fabrication strategies, recent progress, and the challenges that lie ahead.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Mechanical stability of resonant Bose-Fermi mixtures
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-10 20:00 EDT
Christian Gualerzi, Leonardo Pisani, Pierbiagio Pieri
We investigate the mechanical stability of Bose-Fermi mixtures at zero temperature in the presence of a tunable Feshbach resonance, which induces a competition between boson condensation and boson-fermion pairing when the boson density is smaller than the fermion density. Using a many-body diagrammatic approach validated by fixed-node Quantum Monte Carlo calculations and supported by recent experimental observations, we determine the minimal amount of boson-boson repulsion required to guarantee the stability of the mixture across the entire range of boson-fermion interactions from weak to strong coupling. Our stability phase diagrams indicate that mixtures with boson-to-fermion mass ratios near two, such as the $ ^{87}$ Rb-$ ^{40}$ K system, exhibit optimal stability conditions. Moreover, by applying our results to a recent experiment with a $ ^{23}$ Na-$ ^{40}$ K mixture, we find that the boson-boson repulsion was insufficient to ensure stability, suggesting that the experimental timescale was short enough to avoid mechanical collapse. On the other hand, we also show that even in the absence of boson-boson repulsion, Bose-Fermi mixtures become intrinsically stable beyond a certain coupling strength, preceding the quantum phase transition associated with the vanishing of the bosonic condensate. We thus propose an experimental protocol for observing this quantum phase transition in a mechanically stable configuration.
Quantum Gases (cond-mat.quant-gas)
24 pages, 8 figures, article
Response to an external field of a generalized Langevin equation with stochastic resetting of the memory kernel
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Petar Jolakoski, Lasko Basnarkov, Ljupco Kocarev, Aleksandra Popovska-Mitrovikj, Verica Bakeva, Trifce Sandev
We study a generalized Langevin equation (GLE) framework that incorporates stochastic resetting of a truncation power-law memory kernel. The inclusion of stochastic resetting enables the emergence of resonance phenomena even in parameter regimes where conventional settings (without resetting) do not exhibit such behavior. Specifically, we explore the response of the system to an external field under three scenarios: (i) a free particle, (ii) a particle in a harmonic potential, and (iii) the effect of truncation in the memory kernel. In each case, the primary focus is on understanding how the resetting mechanism interacts with standard parameters to induce stochastic resonance. In addition, we explore the effect of resetting on the dielectric loss.
Statistical Mechanics (cond-mat.stat-mech)
Light-field dressing of transient photo-excited states above $E_F$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Fei Wang, Wanying Chen, Changhua Bao, Tianyun Lin, Haoyuan Zhong, Hongyun Zhang, Shuyun Zhou
Time-periodic light-field provides an emerging pathway for dynamically engineering quantum materials by forming hybrid states between photons and Bloch electrons. So far, experimental progress on light-field dressed states has been mainly focused on the occupied states, however, it is unclear if the transient photo-excited states above the Fermi energy $ E_F$ can also be dressed, leaving the dynamical interplay between photo-excitation and light-field dressing elusive. Here, we provide direct experimental evidence for light-field dressing of the transient photo-excited surface states above $ E_F$ , which exhibits distinct dynamics with a delay response as compared to light-field dressed states below $ E_F$ . Our work reveals the dual roles of the pump pulse in both photo-excitation and light-field dressing, providing a more comprehensive picture with new insights on the light-induced manipulation of transient electronic states.
Materials Science (cond-mat.mtrl-sci)
Phys. Rev. Lett. 134, 146401 (2025)
Properties and prevalence of false poor man’s Majoranas in two- and three-site artificial Kitaev chains
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Melina Luethi, Henry F. Legg, Daniel Loss, Jelena Klinovaja
It was predicted that a minimal chain of two quantum dots (QDs) connected via a superconductor can host perfectly localized zero-energy states, known as poor man’s Majoranas (PMMs). It is expected that these states are related to Majorana bound states (MBSs) in longer chains and that the tunable nature of this setup makes it a promising platform to study MBSs. However, realistic systems can only host highly, but not perfectly, localized near-zero-energy states, called imperfect PMMs. It has been shown that these imperfect PMMs can evolve into trivial states unrelated to MBSs when the chain is extended. Such states are called false PMMs, whereas PMMs that evolve into MBSs in long chains are called true PMMs. Here, using a microscopic model of QD-superconductor arrays, we consider properties of false PMMs and the circumstances under which they appear. In two-site systems, we find that the origin of many false PMMs can be related to zero-energy states occurring in the absence of superconductivity and we use this analytic understanding to characterize the false PMMs that are typical for different regions of parameter space. In three-site systems, we show that false PMMs can occur via the same mechanism as for two-site systems, but we also find them in regions of parameter space where they are not predicted to exist, thus hinting that the physics of false PMMs can be richer in longer chains. Finally, we demonstrate that the PMMs most stable to perturbations in chemical potential and with the largest excitation gaps appear in a region of parameter space that also has a large ratio of false to true PMMs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
12 pages, 10 figures
Selective Kondo screening and strange metallicity by sliding Dirac semimetals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
Hanting Zhong, Shuxiang Yang, Chao Cao, Xiao-Yong Feng, Jianhui Dai
Kondo screening of local moments in normal metals typically leads to hybridized conduction and valence bands separated by a Kondo gap, resulting in an insulating state at half-band filling. We show a dramatic change of this scenario in a Dirac-semimetal-based correlated system – a bilayer honeycomb lattice heterostructure where the local moment lattice is stacked on a Dirac semimetal breaking the inversion symmetry. This system is modeled by an extended Anderson honeycomb lattice involving the real-space dependence of major interlayer hybridization parameters on the relative sliding distance along the armchair direction. First, we unveil the multiple Kondo scales and the successive Kondo breakdown transitions in this correlated heterostructure under sliding. Second, we demonstrate the existence of a genuine selective Kondo screening phase which is stabilized near the A-B stack pattern and is accessible by applying the interlayer voltage. Third, we find a nearly flat hybridized band located concomitantly within the Kondo gap, resulting in an unprecedented metallic state at the half-band filling. This unconventional heavy fermion state is characterized by the violation of Luttinger theorem and the appearance of a Van Hove singularity at the Fermi energy. The general sliding-driven band structure landscape and the implications of our results for the broad context of multiorbital Kondo physics are briefly discussed.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 15 figures (including 4 appendices)
Local equations describe unreasonably efficient stochastic algorithms in random K-SAT
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-10 20:00 EDT
David Machado, Jonathan González-García, Roberto Mulet
Despite significant advances in characterizing the highly nonconvex landscapes of constraint satisfaction problems, the good performance of certain algorithms in solving hard combinatorial optimization tasks remains poorly understood. This gap in understanding stems largely from the lack of theoretical tools for analyzing their out-of-equilibrium dynamics. To address this challenge, we develop a system of approximate master equations that capture the behavior of local search algorithms in constraint satisfaction problems. Our framework shows excellent qualitative agreement with the phase diagrams of two paradigmatic algorithms: Focused Metropolis Search (FMS) and greedy-WalkSAT (G-WalkSAT) for random 3-SAT. The equations not only confirm the numerical observation that G-WalkSAT’s algorithmic threshold is nearly parameter-independent, but also successfully predict FMS’s threshold beyond the clustering transition. We also exploit these equations in a decimation scheme, demonstrating that the computed marginals encode valuable information about the local structure of the solution space explored by stochastic algorithms. Notably, our decimation approach achieves a threshold that surpasses the clustering transition, outperforming conventional methods like Belief Propagation-guided decimation. These results challenge the prevailing assumption that long-range correlations are always necessary to describe efficient local search dynamics and open a new path to designing efficient algorithms to solve combinatorial optimization problems.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
Rhombohedral graphite junctions as a platform for continuous tuning between topologically trivial and non-trivial electronic phases
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Luke Soneji, Simon Crampin, Marcin Mucha-Kruczynski
Manipulating the topological properties of quantum states can provide a way to protect them against disorder. However, typically, changing the topology of electronic states in a crystalline material is challenging because their nature is underpinned by chemical composition and lattice symmetry that are difficult to modify. We propose junctions between rhombohedral graphite crystals as a platform that enables smooth transition between topologically trivial and non-trivial regimes distinguished by the absence or presence of topological junction states. By invoking an analogy with the Su-Schrieffer-Heeger model, the appearance of topological states is related to the symmetry of the atomic stacking at the interface between the crystals. The possibility to explore both the topological and non-topological phases is provided by sliding the crystals with respect to each other.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Main: 9 pages, 4 figures; Supplementary: 14 pages, 8 figures
Layer-dependent field-free switching of Néel vector in a van der Waals antiferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Haoran Guo, Zhongchong Lin, Jinhao Lu, Chao Yun, Guanghui Han, Shoutong Sun, Yu Wu, Wenyun Yang, Dongdong Xiao, Zhifeng Zhu, Licong Peng, Yu Ye, Yanglong Hou, Jinbo Yang, Zhaochu Luo
Two-dimensional antiferromagnets, combining the dual advantages of van der Waals (vdW) and antiferromagnetic materials, provide an unprecedented platform for exploring emergent spin-related phenomena. However, electrical manipulation of Néel vectors in vdW antiferromagnets - the cornerstone of antiferromagnetic spintronics - remains challenging. Here, we report layer-dependent electrical switching of the Néel vector in an A-type vdW antiferromagnet $ (Fe,Co)_3$ GaTe_2$ (FCGT) with perpendicular magnetic anisotropy. The Néel vector of FCGT with odd-number vdW layers can be 180° reversed via spin-orbit torques. Furthermore, we achieve field-free switching in an all-vdW, all-antiferromagnet heterostructure of FCGT/CrSBr in which the noncollinear interfacial spin texture breaks the mirror symmetry. Our results establish layer-controlled spin symmetries and interfacial spin engineering as universal paradigms for manipulating antiferromagnetic order, paving the way for realising reliable and efficient vdW antiferromagnetic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Probing Remote Nuclear Magnetic Moments in hBN with VB Electron Spin
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
G.V. Mamin, E.V. Dmitrieva, F.F. Murzakhanov, I.N. Gracheva, E.N. Mokhov, I.I. Vlasov, M.R. Gafurov, U. Gerstmann, V.A. Soltamov
Since the initial discovery of optically addressable spins of the negatively charged boron vacancy defect (VB) in hexagonal boron nitride (hBN), substantial progress has been made, enabling promising applications in quantum sensing, information processing, and simulations. A deep understanding of the VB (electron): hBN (nuclear) spin systems is crucial for realizing these potentials. In this article, we employ Electron Nuclear Double Resonance (ENDOR) to demonstrate the sensing of dis tant nuclear spins via the VB electron spin. We identify the nature and localization of the probed nuclear magnetic moments as 14N spins localized 0.4 nm away from the vacancy and resolve the energies of the corresponding interactions. Density Functional Theory (DFT) calculations further confirm these findings, providing a detailed description of the interactions between the VB electron spin and surrounding nitrogen atoms in different shells. The results establish the VB electron spin as a promising tool for developing novel van der Waals material-based nuclear magnetic resonance (NMR) probes, advancing the understanding of spin physics in hBN, and unlocking its potential to study distant nuclear spin interactions in the host.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Solid-State Maser with Microwatt Output Power at Moderate Cryogenic Temperatures
New Submission | Other Condensed Matter (cond-mat.other) | 2025-04-10 20:00 EDT
Yefim Varshavsky, Oleg Zgadzai, Aharon Blank
Solid-state masers are uniquely positioned to serve as ultra-low phase noise microwave sources due to their exceptionally low noise temperatures. However, their practical application has been historically limited by low output power and the need for deep cryogenic cooling. In this work, we present a novel design for a continuous-wave diamond-based maser oscillator operating at about 14.5 GHz and moderate cryogenic temperatures (about 180 K), achieving output power levels exceeding -30 dBm (1 microW). This performance represents a two-orders-of-magnitude improvement over previous diamond or ruby-based maser this http URL system integrates a high-Q (about 2460) compact metallic microwave cavity with optically pumped (111)-oriented NV-rich diamond crystals. The cavity supports efficient light coupling and thermal dissipation, enabling sustained high-power optical excitation (>1 W) using cost-effective green LEDs. We demonstrate stable maser operation with good spectral quality and validate its output through both frequency- and time-domain analysis with phase noise data when operated in “free running” mode. Additionally, we provide phase noise estimations based on Leeson’s model and show that, when coupled to a high-Q external resonator, such masers could approach thermally limited phase noise levels. These predictions suggest strong potential for diamond masers to outperform traditional ruby-based or similar maser systems, especially given their ability to operate at higher temperatures using rugged, He-free Stirling coolers. Despite current limitations related to frequency stability and jitter, this work establishes diamond-based masers as promising candidates for next-generation ultra-low phase noise microwave oscillators. Further engineering optimization - particularly in field stability, thermal regulation, and feedback locking - will be key to unlocking their full potential.
Other Condensed Matter (cond-mat.other)
18 pages, 7 figures
Extended study of crystal structures, optical properties and vibrational spectra of polar 2-aminopyrimidinium hydrogen phosphite and bis(2-aminopyrimidinium) sulfate monohydrate and two 2-aminopyrimidinium hydrogen sulfate polymorphs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Irena Matulkova, Ladislav Bohaty, Petra Becker, Ivana Cisarova, Robert Gyepes, Michaela Fridrichova, Jan Kroupa, Petr Nemec, Ivan Nemec
This study aimed primarily at completing and extending the characterization of the crystallographic, spectroscopic and optical properties of polar, biaxial, optically negative 2-aminopyrimidinium(1+) hydrogen phosphite. Besides the redetermination of the low-temperature crystal structure (space group P21), high-quality single crystals of this salt were grown from an aqueous solution, and their optical properties were studied. The determination of the refractive indices in the wavelength range of 435-1083 nm showed anomalous dispersion of the refractive indices, resulting in a point of uniaxiality. The crystal allows phase matching for collinear second harmonic generation (SHG) processes of both type I and type II in a broad wavelength range. SHG properties were studied for powdered size-fractioned samples and oriented single-crystal cuts. The optical damage threshold experiments confirmed excellent optical resistance - at least 220 TWm-2 and 70 TWm-2 for 800 and 1000 nm irradiation, respectively. The low-temperature crystallographic study was also extended for three monoclinic salts of 2-aminopyrimidine and sulfuric acid - i.e. bis(2-aminopyrimidinium(1+) sulfate monohydrate (space group P21/n) and two polymorphs of 2-aminopyrimidinium(1+) hydrogen sulfate (both with space group P21/c). The vibrational spectra of all title compounds were assigned using single-molecule quantum chemical computations (including Potential Energy Distribution analysis) in combination with the nuclear site group analysis. Spectroscopic results concerning sulfates of 2-aminopyrimidine provided valuable reference materials for the vibrational spectroscopic study and also addressed the question of their polymorphism. An optimal computational approach employing solid-state DFT calculations has also been sought to model the vibrational spectra of 2-aminopyrimidinium (1+) hydrogen phosphite crystals.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Numerical renormalization of glassy dynamics
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-10 20:00 EDT
Johannes Lang, Subir Sachdev, Sebastian Diehl
The quench dynamics of glassy systems are challenging. Due to aging, the system never reaches a stationary state but instead evolves on emergent scales that grow with its age. This slow evolution complicates field-theoretic descriptions, as the weak long-term memory and the absence of a stationary state hinder simplifications of the memory, always leading to the worst-case scaling of computational effort with the cubic power of the simulated time. Here, we present an algorithm based on two-dimensional interpolations of Green’s functions, which resolves this issue and achieves sublinear scaling of computational cost. We apply it to the quench dynamics of the spherical mixed $ p$ -spin model to establish the existence of a phase transition between glasses with strong and weak ergodicity breaking at a finite temperature of the initial state. By reaching times three orders of magnitude larger than previously attainable, we determine the critical exponents of this transition. Interestingly, these are continuously varying and, therefore, non-universal. While we introduce and validate the method in the context of a glassy system, it is equally applicable to any model with overdamped excitations.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
5 pages, 2 figures
Quantum controlling and the topological properties of the magnon photo-transport in two-dimensional collinear ferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
In our work, we study magnon transport induced by light through Aharonov-Casher (AC) effect, including magnon spin photocurrent (MSPC) and magnon energy photocurrent (MEPC). Firstly, we regard the effect of the electric field on the magnon through the AC effect as a perturbation. Then we derived the expressions of MSPC and MEPC in two-dimensional collinear ferromagnetic system. And we apply our theory to the two-dimension ferromagnetic Hexagonal and Kagome lattice. We find that the optical frequency and the relaxation time of the material can be used to control the photo-transport of magnons. In addition, under the condition of low light frequncy and infinite relaxation time, the longitudinal magnon photo-transport is related to the topological property of the magnon system.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages, 8 figures
Magnetic ground state discrimination of a Polyradical Nanog-raphene using Nickelocene-Functionalized Tips
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Diego Soler-Polo, Oleksandr Stetsovych, Manish Kumar, Benjamin Lowe, Ana Barragán, Zhiqiang Gao, Andrés Pinar Solé, Hao Zhao, Elena Pérez-Elvira, Goudappagouda, David Écija, Akimitsu Narita, Pavel Jelínek, José I. Urgel
Molecular magnets are a promising class of materials with exciting properties and applications. However, a profound understanding and application of such materials depends on the accurate detection of their electronic and magnetic properties. Despite the availability of experimental techniques that can sense the magnetic signal, the exact determination of the spin ground states and spatial distribution of exchange interaction of strongly correlated single-molecule magnets remains challenging. Here, we demonstrate that scanning probe microscopy with a nickelocene-functionalized probe can distinguish between nearly degenerate multireference ground states of single-molecule {\pi}-magnets and map their spatial distribution of the exchange interaction. This method expands the already outstanding imaging capabilities of scanning probe microscopy for characterizing the chemical and electronic structures of individual molecules, paving the way for the study of strongly correlated molecular magnets with unprecedented spatial resolution.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Emergent Theory for Constitutive Relations in Classical Defect Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Optical, acoustic, hydrodynamic, and thermal defect systems are often studied by analogy with each other. This may indicate that we may find a emergent theory for constitutive relations of classical defect systems. Start with thermal systems, we put up with a bootstrap method to describe classical transport. We conjecture that Landau-Khalatnikov equation could provide heat constitutive relations when taking heat flux as order parameter. We show that the corresponding effctive Lagrangian has similar form of that of Wick-rotated complex scalar field theory at non-relativistic limit, and only in perfect conducting situation that this system is a canonical ensemble. We argue that our method could be generalized to other systems besides thermal ones. By analogy with ferroelectrics, we propose the thermal domain model, which is a conserved current XY model. Phase transition of the thermal system is qualitatively discussed in this model.
Statistical Mechanics (cond-mat.stat-mech), Superconductivity (cond-mat.supr-con), High Energy Physics - Theory (hep-th)
Optical imaging of spontaneous electric polarizations in tetralayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Zhou Zhou, Xiyao Peng, Jianfeng Bi, Fei Xue, Jie Jiang, Huizhen Wu, Zhiwen Shi, Haoliang Qian, Toshikaze Kariyado, Sihan Zhao
The recent discovery of sliding ferroelectricity has sparked intense interests in studying interfacial polarizations in two-dimensional (2D) van der Waals materials. However, akin to the conventional ferroelectrics, the studies have predominantly reported semiconducting and/or insulating moiré systems and binary compounds. Spontaneous electric polarizations in elemental metallic phases remain scarcity. Here, we report the first optical imaging of intrinsic out-of-plane electric polarizations and domain wall (DW) sliding dynamics in tetralayer graphene, a 2D conductive layer composed entirely of carbon. Using scanning near-field optical microscopy (SNOM), we directly visualize adjacent ABAC and ABCB stacking orders with intrinsic and opposite electric polarizations. Our gate-dependent SNOM measurements reveal distinct optical response that systematically changes upon carrier doping and unconventional interplay between DW sliding and electric polarizations, which are supported by density functional theory (DFT) calculations. Independent corroboration through Kelvin probe force microscopy (KPFM) and Raman spectroscopy confirms the polar nature and their polarization directions. Furthermore, reversible mechanical switching of polar states via atomic force microscopy (AFM) tip manipulation is also demonstrated. Our work establishes SNOM as a critical tool for probing sliding ferroelectricity in conductive 2D layers, opening avenues for exploring multiferroic behaviors and nonvolatile memory applications in atomically thin metals at room temperature.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
43 pages; 4 figures, 22 supplementary data figures, etc
Surface Oxidation of SnTe Analyzed by Self-Consistent Fitting of all Emission Peaks in its X-ray Photoelectron Spectrum
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Martin Wortmann, Beatrice Bednarz, Negin Beryani Nezafat, Klaus Viertel, Olga Kuschel, Jan Schmalhorst, Inga Ennen, Maik Gärner, Natalie Frese, Gerhard Jakob, Joachim Wollschläger, Gabi Schierning, Andreas Hütten, Timo Kuschel
X-ray photoelectron spectroscopy (XPS) is among the most widely used methods for surface characterization. Currently, the analysis of XPS data is almost exclusively based on the main emission peak of a given element and the rest of the spectrum is discarded. This makes quantitative chemical state analyses by peak fitting prone to substantial error, especially in light of incomplete and flawed reference literature. However, most elements give rise to multiple emission peaks in the x-ray energy range, which are virtually never analyzed. For samples with an inhomogeneous depth distribution of chemical states, these peaks show different but interdependent ratios of signal components, as they correspond to different information depths. In this work, we show that self-consistent fitting of all emission peaks lends additional reliability to the depth profiling of chemical states by angular-resolved (AR-)XPS. We demonstrate this using a natively oxidized thin film of the topological crystalline insulator tin telluride (SnTe). This approach is not only complementary to existing depth profiling methods, but may also pave the way towards complete deconvolution of the XPS spectrum, facilitating a more comprehensive and holistic understanding of the surface chemistry of solids.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
main article 13 pages, 6 figures; supporting information 8 pages, 6 figures
CRYSIM: Prediction of Symmetric Structures of Large Crystals with GPU-based Ising Machines
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Chen Liang, Diptesh Das, Jiang Guo, Ryo Tamura, Zetian Mao, Koji Tsuda
Solving black-box optimization problems with Ising machines is increasingly common in materials science. However, their application to crystal structure prediction (CSP) is still ineffective due to symmetry agnostic encoding of atomic coordinates. We introduce CRYSIM, an algorithm that encodes the space group, the Wyckoff positions combination, and coordinates of independent atomic sites as separate variables. This encoding reduces the search space substantially by exploiting the symmetry in space groups. When CRYSIM is interfaced to Fixstars Amplify, a GPU-based Ising machine, its prediction performance was competitive with CALYPSO and Bayesian optimization for crystals containing more than 150 atoms in a unit cell. Although it is not realistic to interface CRYSIM to current small-scale quantum devices, it has the potential to become the standard CSP algorithm in the coming quantum age.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
18 pages, 4 figures, 1 table
Brillouin Platycosms and Topological Phases
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Chen Zhang, Peiyuan Wang, Junkun Lyu, Y. X. Zhao
There exist ten distinct closed flat $ 3$ D manifolds, known as platycosms, which hold significance in mathematics and have been postulated as potential geometric models for our universe. In this work, we demonstrate their manifestation as universes of Bloch particles, namely as momentum-space units referred to as Brillouin platycosms, which are natural extensions of the Brillouin torus within a broader framework of projective crystallographic symmetries. Moreover, we provide exact K-theoretical classifications of topological insulators over these platycosms by the Atiyah-Hirzebruch spectral sequence, and formulate a complete set of topological invariants for their identification. Topological phase transitions are generically characterized by Weyl semimetals, adhering to the generalized Nielsen-Ninomiya theorem: the total chirality number over a Brillouin platycosm is even (zero) if the platycosm is non-orientable (orientable). Our work generalizes the notion of Brillouin torus to ten Brillouin platycosms and therefore fundamentally diversifies the stages on which Block wavefunctions can perform their topological dance.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Identifying and mitigating errors in hole spin qubit readout
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Eoin Gerard Kelly, Leonardo Massai, Bence Hetényi, Marta Pita-Vidal, Alexei Orekhov, Cornelius Carlsson, Inga Seidler, Konstantinos Tsoukalas, Lisa Sommer, Michele Aldeghi, Stephen W. Bedell, Stephan Paredes, Felix J. Schupp, Matthias Mergenthaler, Andreas Fuhrer, Gian Salis, Patrick Harvey-Collard
High-fidelity readout of spin qubits in semiconductor quantum dots can be achieved by combining a radio-frequency (RF) charge sensor together with spin-to-charge conversion and Pauli spin blockade. However, reaching high readout fidelities in hole spin qubits remains elusive and is complicated by a combination of site-dependent spin anisotropies and short spin relaxation times. Here, we analyze the different error processes that arise during readout using a double-latched scheme in a germanium double quantum dot hole spin qubit system. We first investigate the spin-to-charge conversion process as a function of magnetic field orientation, and configure the system to adiabatically map the $ \lvert \downarrow\downarrow \rangle$ state to the only non-blockaded state. We reveal a strong dependence of the spin relaxation rates on magnetic field strength and minimize this relaxation by operating at low fields. We further characterize and mitigate the error processes that arise during the double-latching process. By combining an RF charge sensor, a double-latching process, and optimized magnetic field parameters, we achieve a single-shot single-qubit state-preparation-and-measurement fidelity of 97.0%, the highest reported fidelity for hole spin qubits. Unlike prior works and vital to usability, we simultaneously maintain universal control of both spins. These findings lay the foundation for the reproducible achievement of high-fidelity readout in hole-based spin quantum processors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Activated solids: Spontaneous deformations, non-affine fluctuations, softening, and failure
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-10 20:00 EDT
Parswa Nath, Debankur Das, Surajit Sengupta, Debasish Chaudhuri
We investigate spontaneous deformations in activated solids by analyzing crystal deformations through non-affine fluctuations. A scaling law for non-affinity is derived, showing it scales quadratically with activity and inversely with density. At high activity, the non-affine parameter diverges, signaling defect proliferation and melting to a hexatic phase. This softening is marked by reduced shear modulus, solid order, and hexatic order. At a higher activity, the hexatic melts to a fluid. We propose locally tuned activity to control non-affinity, demonstrated through numerical simulations. Our predictions are testable in active colloids performing persistent random motion.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
11 pages, 10 figures
Kinetic phase diagram for two-step nucleation in colloid-polymer mixtures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-10 20:00 EDT
Willem Gispen, Peter G. Bolhuis, Marjolein Dijkstra
Two-step crystallization via a metastable intermediate phase is often regarded as a non-classical process that lies beyond the framework of classical nucleation theory (CNT). In this work, we investigate two-step crystallization in colloid-polymer mixtures via an intermediate liquid phase. Using CNT-based seeding simulations, we construct a kinetic phase diagram that identifies regions of phase space where the critical nucleus is either liquid or crystalline. These predictions are validated using transition path sampling simulations at nine different relevant state points. When the critical nucleus is liquid, crystallization occurs stochastically during the growth phase, whereas for a crystalline critical nucleus, the crystallization process happens pre-critically at a fixed nucleus size. We conclude that CNT-based kinetic phase diagrams are a powerful tool for understanding and predicting `non-classical’ crystal nucleation mechanisms.
Soft Condensed Matter (cond-mat.soft)
18 pages
J. Chem. Phys. 162, 134901 (2025)
Generic deformation channels for critical Fermi surfaces including the impact of collisions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
Kazi Ranjibul Islam, Ipsita Mandal
This paper constitutes a sequel to our theoretical efforts to determine the nature of the generic low-energy deformations of the Fermi surface of a quantum-critical metal, which arises at the stable non-Fermi liquid (NFL) fixed point of a quantum phase transition. The emergent critical Fermi surface, arising right at the Ising-nematic quantum critical point (QCP), is a paradigmatic example where an NFL behaviour is induced by the strong interactions of the fermionic degrees of freedom with those of the bosonic order parameter. It is an artifact of the bosonic modes becoming massless at the QCP, thus undergoing Landau damping at the level of one-loop self-energy. We resort to the well-tested formalism of the quantum Boltzmann equations (QBEs)for identifying the excitations. While in our earlier works, we have focussed on the collisionless regime by neglecting the collision integral and assuming the bosons to be in equilibrium, here we embark on a full analysis. In particular, we take into account the bosonic part of the QBEs. The final results show that that the emergent modes are long-lived and robust against the damping effects brought about the collision integral(s), exhibiting the same qualitative features as obtained from the no-collision approximations.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th)
follow up paper of arXiv:2108.09480 and arXiv:2304.04720
Exact Ground States of Two Dimensional $\pm J$ Spin Glasses
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-10 20:00 EDT
We derive exact analytical expressions for the ground-state energy and entropy of the two-dimensional $ \pm J$ Ising spin glass, uncovering a nested hierarchy of frustrations. Each level in this hierarchy contributes through the kernel and pseudo-determinant of effective operators, capturing the energy and entropy, respectively. At leading order, the structure coincides with geometric plaquette frustrations, while subleading corrections arise from magnetic adjacency matrices defined on percolated clusters in the dual lattice. Our results, supported by numerical simulations, provide a systematic framework for analyzing spin-glass ground states and offer new insight into glass order in finite dimensions.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
Signatures of unconventional superconductivity near reentrant and fractional quantum anomalous Hall insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-10 20:00 EDT
Fan Xu, Zheng Sun, Jiayi Li, Ce Zheng, Cheng Xu, Jingjing Gao, Tongtong Jia, Kenji Watanabe, Takashi Taniguchi, Bingbing Tong, Li Lu, Jinfeng Jia, Zhiwen Shi, Shengwei Jiang, Yuanbo Zhang, Yang Zhang, Shiming Lei, Xiaoxue Liu, Tingxin Li
Two-dimensional moiré Chern bands provide an exceptional platform for exploring a variety of many-body electronic liquid and solid phases at zero magnetic field within a lattice system. One particular intriguing possibility is that flat Chern bands can, in principle, support exotic superconducting phases together with fractional topological phases. Here, we report the observation of integer and fractional quantum anomalous Hall effects, the reentrant quantum anomalous Hall effect, and superconductivity within the first moiré Chern band of twisted bilayer MoTe2. The superconducting phase emerges from a normal state exhibiting anomalous Hall effects and sustains an large perpendicular critical magnetic field. Our results present the first example of superconductivity emerging within a flat Chern band that simultaneously hosts fractional quantum anomalous effects, a phenomenon never observed in any other systems. Our work expands the understanding of emergent quantum phenomena in moiré Chern bands, and offers a nearly ideal platform for engineering Majorana and parafermion zero modes in gate-controlled hybrid devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Exact Current Fluctuations in a Tight-Binding Chain with Dephasing Noise
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Taiki Ishiyama, Kazuya Fujimoto, Tomohiro Sasamoto
For a tight-binding chain with dephasing noise on an infinite interval, we exactly calculate the variance of the integrated current for a step initial condition with average densities, $ \rho_a$ on the negative axis and $ \rho_b$ on the positive axis. Our exact solution reveals that the presence of dephasing, no matter how small, alters the nature of current fluctuations from ballistic to diffusive in the long-time limit. The derivation relies on the Bethe ansatz on the infinite interval and a nontrivial parameter dependence, referred to as the $ \omega$ -dependence, of the moment generating function for the integrated current. Furthermore, we demonstrate that the asymptotic form of the variance and a numerically obtained cumulant generating function coincide with those in the symmetric simple exclusion process.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
22 pages, 6 figures
Enhancing TiFe Alloy Activation for Hydrogen Storage Through Al, Cr, Co, and Cu Substitutions as a Step Towards Future Recycling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Francesca Garelli, Erika Michela Dematteis, Vitalie Stavila, Giuseppe Di Florio, Claudio Carbone, Alessandro Agostini, Mauro Palumbo, Marcello Baricco, Paola Rizzi
This study investigates the activation behavior of $ TiFe_{0.80}$ -$ X_{0.20}$ (X = Co, Cu, Cr, Al) alloys to identify the most effective materials for producing hydrogen storage alloys from recycled sources in view of a circular economy perspective. Activation was tested using two methods: a Sievert Volumetric Apparatus at room temperature and 64 bar of hydrogen, and high-pressure differential scanning calorimetry with 50 bar hydrogen under thermal cycles up to 400 °C. Activation properties were analyzed by assessing time for incubation and for full charging, that are influenced, respectively, by surface and bulk diffusion of hydrogen. Results showed that Cr-substituted alloys are rapidly activated, due to the presence of $ TiCr_{2}$ compound, while Al-containing alloys absorbed hydrogen immediately. In contrast, Co- and Cu-substituted alloys required extended activation times, due to less quantity of secondary phases and limited diffusion channels.
Materials Science (cond-mat.mtrl-sci)
Screening of material defects using universal machine-learning interatomic potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Ethan Berger, Mohammad Bagheri, Hannu-Pekka Komsa
Finding new materials with previously unknown atomic structure or materials with optimal set of properties for a specific application greatly benefits from computational modeling. Recently, such screening has been dramatically accelerated by the invent of universal machine-learning interatomic potentials that offer first principles accuracy at orders of magnitude lower computational cost. Their application to the screening of defects with desired properties or to finding new stable compounds with high density of defects, however, has not been explored. Here, we show that the universal machine-learning interatomic potentials have reached sufficient accuracy to enable large-scale screening of defective materials. We carried out vacancy calculations for 86 259 materials in the Materials Project database and analyzed the formation energies in terms of oxidation numbers. We further demonstrate the application of these models for finding new materials at or below the convex hull of known materials and for simulated etching of low-dimensional materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Data-Driven Insights into Rare Earth Mineralization: Machine Learning Applications Using Functional Material Synthesis Data
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Juejing Liu, Xiaoxu Li, Yifu Feng, Zheming Wang, Kevin M. Rosso, Xiaofeng Guo, Xin Zhang
Quantitative understanding of rare earth element (REE) mineralization mechanisms, crucial for improving industrial separation, remains limited. This study leverages 1239 hydrothermal synthesis datapoints from material science as a surrogate for natural REE mineralization. We trained machine learning models (KNN, RF, XGBoost) using precursor, additive, and reaction data to predict product elements and phases, validating predictions with new experiments. XGBoost exhibited the highest accuracy, with feature importance analysis indicating thermodynamic properties were critical for predictions. Observed correlations among reaction parameters aligned with classical crystallization theory. Further XGBoost models successfully predicted reaction temperature and pH from precursor/product data. Our findings demonstrate the cross-disciplinary utility of material science data for geochemical understanding, underscore the need for research on less-studied REE minerals (e.g., carbonates, heavy REEs), and suggest potential to accelerate REE resource development.
Materials Science (cond-mat.mtrl-sci)
Fermi surface as a quantum critical manifold: gaplessness, order parameter, and scaling in $d$-dimensions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
We study several models of $ d$ -dimensional fermions ($ d=1,2,3$ ) with an emphasis on the properties of their gapless (metallic) phase. It occurs at $ T = 0$ as a continuous transition when zeros of the partition function reach the real range of parameters. Those zeros define the $ (d-1)$ -manifold of quantum criticality (Fermi surface). Its appearance or restructuring correspond to the Lifshitz transition. Such $ (d-1)$ -membrane breaks the symmetry of the momentum space, leading to gapless excitations, a hallmark of metallic phase. To probe quantitatively the gapless phase we introduce the geometric order parameter as $ d$ -volume of the Fermi sea. From analysis of the chain, ladder, and free fermions with different spectra, this proposal is shown to be consistent with scaling near the Lifshitz points of other quantities: correlation length, oscillation wavelength, susceptibilities, and entanglement. All the (hyper)scaling relations are satisfied. Two interacting cases of the Tomonaga-Luttinger ($ d=1$ ) and the Fermi ($ d=2,3$ ) liquids are analysed, yielding the same universality classes as free fermions.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
27 pages (15 pp main text, 2 appendices), 5 figures
Non-Hermitian Numerical Renormalization Group: Solution of the non-Hermitian Kondo model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
Phillip C. Burke, Andrew K. Mitchell
Non-Hermitian (NH) Hamiltonians describe open quantum systems, nonequilibrium dynamics, and dissipative processes. Although a rich range of single-particle NH physics has been uncovered, many-body phenomena in strongly correlated NH systems have been far less well studied. The Kondo effect, an important paradigm for strong correlation physics, has recently been considered in the NH setting. Here we develop a NH generalization of the numerical renormalization group (NRG) and use it to solve the NH Kondo model. Our non-perturbative solution applies beyond weak coupling, and we uncover a nontrivial phase diagram. The method is showcased by application to the NH pseudogap Kondo model, which we show supports a completely novel phase with a genuine NH stable fixed point and complex eigenspectrum. Our NH-NRG code, which can be used in regimes and for models inaccessible to, e.g., perturbative scaling and Bethe ansatz, is provided open source.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Main text: 5 pages, 3 figures. End matter: 2 pages, 1 figure. Supplemental material: 7 pages, 4 figures
Hydrogen-Mediated Control of Phase Formation and Microstructure Evolution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Lukas Schweiger, Florian Spieckermann, Peter Cengeri, Alexander Schökel, Michael Zehetbauer, Erhard Schafler, Daniel Kiener, Jürgen Eckert
Hydrogen is key in reducing greenhouse gas emissions in materials production. At the same time, it significantly affects mechanical properties, often causing unwanted embrittlement. However, rather than solely addressing these disadvantages, hydrogens inevitable role in sustainable metallurgy should be leveraged to create new and potentially superior materials. Here, we show that using hydrogen in the form of metal hydrides introduces a barrier to mechanical alloying, stabilizing otherwise unattainable microstructures. Severe plastic deformation of a composite of the high entropy alloy (HEA) TiVZrNbHf and Cu leads to amorphization while substituting the HEA by its hydride preserves the two-phase structure. Monte Carlo simulations confirm that the significantly different hydrogen affinities, together with the restricted dislocation motion in the hydride, create a barrier to mechanical alloying. This hydride route enables new microstructural states, even in well-studied material systems. It opens an additional dimension in designing materials with diverging hydrogen affinities, offering tighter control over mechanical alloying.
Materials Science (cond-mat.mtrl-sci)
Manuscript plus Supplementary Information
Harnessing non-equilibrium forces to optimize work extraction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-10 20:00 EDT
Kristian Stølevik Olsen, Rémi Goerlich, Yael Roichman, Hartmut Löwen
While optimal control theory offers effective strategies for minimizing energetic costs in noisy microscopic systems over finite durations, a significant opportunity lies in exploiting the temporal structure of non-equilibrium forces. We demonstrate this by presenting exact analytical forms for the optimal protocol and the corresponding work for any driving force and protocol duration. We also derive a general quasistatic bound on the work, relying only on the coarse-grained, time-integrated characteristics of the applied forces. Notably, we show that the optimal protocols often automatically act as information engines that harness information about non-equilibrium forces and an initial state measurement to extract work. These findings chart new directions for designing adaptive, energy-efficient strategies in noisy, time-dependent environments, as illustrated through our examples of periodic driving forces and active matter systems. By exploiting the temporal structure of non-equilibrium forces, this largely unexplored approach holds promise for substantial performance gains in microscopic devices operating at the nano- and microscale.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Minimal mechanism for fluidic flocks in interacting active colloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-10 20:00 EDT
Arvin Gopal Subramaniam, Sagarika Adhikary, Rajesh Singh
Collective motion as a flock is a widely observed phenomenon in active matter systems. Finding possible mechanisms of attaining a global polar order via dynamical mechanisms - without any explicit alignment interaction - is an area of active current research. Here, we report a flocking transition sustained purely by chemo-repulsive torques at low to medium densities in a system of chemically interacting colloidal particles. The basic requirements to sustain the flock are excluded volume repulsions and deterministic long-ranged net repulsive torques, with the time scale individual colloids move a unit length being dominant with respect to the time they deterministically sense chemicals. Switching on the translational repulsive forces renders the flock a crystalline structure. The generality of this phenomenon is displayed for a range of attractive translational forces to which the flock is robust. We rationalize these results with a phenomenological hydrodynamical model.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Universal neural wave functions for high-pressure hydrogen
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-10 20:00 EDT
David Linteau, Saverio Moroni, Giuseppe Carleo, Markus Holzmann
We leverage the power of neural quantum states to describe the ground state wave function of solid and liquid dense hydrogen, including both electronic and protonic degrees of freedom. For static protons, the resulting Born-Oppenheimer energies are consistently lower than all previous projector Monte Carlo calculations for systems containing up to $ 128$ hydrogen atoms. In contrast to conventional methods, we introduce a universal trial wave function whose variational parameters are optimized simultaneously over a large set of proton configurations spanning a wide pressure-temperature spectrum and covering both molecular and atomic phases. This global optimization not only yields lower energies compared to benchmarks but also brings an enormous reduction in computational cost. By including nuclear quantum effects in the zero-temperature ground state, thus going beyond the Born-Oppenheimer approximation, our description overcomes major limitations of current wave functions, notably by avoiding any explicit symmetry assumption on the expected quantum crystal and sidestepping efficiency issues of imaginary time evolution with disparate mass scales. As a first application, we examine crystal formation in an extremely high-density region where pressure-induced melting is expected.
Strongly Correlated Electrons (cond-mat.str-el)
Intertwining Josephson and Vortex Topologies in Conventional Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Zhuo Chen, Jiangxu Li, Lun-Hui Hu, Zhen Bi, Rui-Xing Zhang
Recent experimental advances have unveiled promising evidence of vortex-bound Majorana quasiparticles in multiple superconducting compounds. However, theoretical progress in understanding these phenomena, especially from ab initio approaches, has been limited by the computational complexity of simulating vortex structures. To bridge this gap, we introduce the Josephson-vortex correspondence (JVC), a theoretical framework that systematically maps the bound-state topological properties of vortices to those of $ \pi$ -phase Josephson junctions in the same superconductor. This correspondence allows vortex phase diagrams to be constructed directly from junction calculations, thereby eliminating the need for large-scale vortex calculations. We demonstrate the validity and predictive power of JVC across a variety of effective models, and further extend the framework to the first-principles level. Applying our approach to 2M-WS$ _2$ and Sr$ _3$ SnO, we identify them as realistic, doping-tunable platforms for realizing vortex Majorana zero modes. Our theory will pave the way for ab initio Majorana material discovery and design.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 7 figures
Spin state of iron in I-42d-type Mg2SiO4 at ultra-high pressures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-10 20:00 EDT
Tianqi Wan, Yang Sun, Renata M. Wentzcovitch
At extreme pressures of approximately 500 GPa, conditions characteristic of the deep interiors of super-Earths, the combination of NaCl-type MgO and post-perovskite-type MgSiO3 (PPv) has been reported to produce a post-PPv phase of Mg2SiO4 with an I-42d symmetry. This post-PPv (pppv) silicate is proposed as the primary mantle silicate in these massive rocky exoplanets. Understanding the fundamental properties of pppv, particularly in solid solutions with Fe2SiO4, is crucial for insights into the interior dynamics and compositions of such planets. In this study, we conduct an ab initio investigation of the properties of Fe2+-bearing pppv at pressures ranging from 400 GPa to 1 TPa. Given the localized nature of 3d-electrons in iron, we employ the LDA+Usc method alongside conventional DFT functionals to probe the electronic structure of this system. The dependence of the Hubbard parameter U on volume and spin state is carefully evaluated. Furthermore, we systematically explore the effects of pressure, temperature, and structural variations on the spin state of iron in Fe2+-bearing pppv, providing valuable data to improve mantle modeling for super-Earth-type exoplanets.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Chiral superconductivity from spin polarized Chern band in twisted MoTe$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Cheng Xu, Nianlong Zou, Nikolai Peshcherenko, Ammar Jahin, Tingxin Li, Shi-Zeng Lin, Yang Zhang
Superconductivity has been observed in twisted MoTe2 within the anomalous Hall metal parent state. Key signatures-including a fully spin/valley polarized normal state, anomalous Hall resistivity hysteresis, superconducting phase adjacent to the fractional Chern insulating state and a narrow superconducting dome at zero gating field-collectively indicate chiral superconductivity driven by intravalley pairing of electrons. Within the Kohn-Luttinger mechanism, we compute the superconducting phase diagram via random phase approximation, incorporating Coulomb repulsion in a realistic continuum model. Our results identify a dominant intravalley pairing with a narrow superconducting dome of p+ip type at zero gate field. This chiral phase contrasts sharply with the much weaker time-reversal-symmetric intervalley pairing at finite gating field. Our work highlights the role of band topology in achieving robust topological superconductivity, and supports the chiral and topological nature of the superconductivity observed in twisted MoTe2.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
5 pages + 4 figures
Pauli ‘unlimited’: magnetic field induced-superconductivity in UTe$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-10 20:00 EDT
Josephine J. Yu, Yue Yu, Chaitanya Murthy, Srinivas Raghu
Inspired by the observation of extreme field-boosted superconductivity in uranium ditelluride, we present a scenario in which superconductivity can be induced by a strong Zeeman field, rather than destroyed by it, as is the case in Pauli-limited superconductivity. The resulting superconducting state has an upper critical field far greater than the superconducting transition temperature, and with spin-orbit coupling, it is sensitive to the field orientation. We demonstrate the interplay between superconductivity and metamagnetism in a simple effective theory.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)