Quantum Gases · Cross-listed from nlin.PS
Dispersive shock waves in periodic lattices
Su Yang, Sathyanarayanan Chandramouli and Panayotis G. Kevrekidis
We introduce and systematically investigate the generation of dispersive shock waves, which arise naturally in physical settings such as optical waveguide arrays and superfluids confined within optical
lattices. The underlying physically relevant model is a nonlinear Schrödinger (NLS) equation with a periodic potential. We consider the
evolution of piecewise smooth initial data composed of two distinct nonlinear periodic eigenmodes. To begin interpreting the resulting wave dynamics, we employ the tight-binding approximation, reducing the continuous system to a discrete NLS (DNLS) model with piecewise constant initial data (i.e., a Riemann problem), where each constant state represents a discrete Floquet-Bloch mode at the continuum model level. The resulting tight-binding approximation is shown to display higher-fidelity for {deeper} periodic potentials. This reduced DNLS model effectively models the dynamics at the minima of the periodic potential of the original continuum NLS. Within such a single-band DNLS framework, we apply tools from Whitham modulation theory and long-wave quasi-continuum reductions to uncover and analyze a rich spectrum of non-convex, discrete dispersive hydrodynamic phenomena, comparing the resulting phenomenology with that of the periodic-potential-bearing continuum model.
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Other Condensed Matter · Cross-listed from quant-ph
Systems with Quantum Dimensions
Mikołaj Myszkowski, Mattia Damia Paciarini and Francesco Sannino
We propose
quantum-mechanical systems in which the number of spatial dimensions is promoted to a dynamical
quantum variable, making the effective dimension state-dependent. Interestingly, systems of this form can exhibit enhanced
symmetries compared to their fixed-dimensional counterparts. As an explicit example, we analyze a two-state system for which the number of spatial dimensions is represented by a
quantum operator. By evaluating the corresponding partition function, we uncover a temperature-dependent effective dimension. Our framework opens a new avenue for constructing physical systems, from
gravity to condensed matter, where the very notion of dimensionality becomes
quantum.
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Soft Condensed Matter
Analytic theory of shear localization in amorphous solids confined by Couette geometry
Yang Fu, Yuliang Jin and Itamar Procaccia
“Couette geometry” refers to two concentric rings in 2-dimensions (or cylinders in 3-dimensions with a medium in between). Typically the inner and outer rings (or cylinders) rotate at different rates and the response of the medium is studied. Here we study a medium which is a two-dimensional amorphous solid, and we rotate the inner ring quasi-statically. As stress accumulates, plastic avalanches can result in shear localization, characterized by adjacent parts of the system rotating in opposite directions, with the maximum shear localized between them. We derive an analytic theory that describes and explains the shear localization, providing a-priori predictions for the angle-averaged displacement field associated with the plastic drops and the shear localization.
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Strongly Correlated Electrons
Neural network impurity solver for real-frequency dynamical mean-field theory
Fenglin Deng, Yi Lu, Xiaodong Cao et al. (+1 more)
We introduce a neural network
impurity solver for real-frequency DMFT that employs a multihead cross-
attention mechanism to map hybridization functions to spectral functions, conditioned on
impurity parameters. Trained on high-quality MPS data from complex contour time
evolution and incorporating derivative constraints with respect to the complex-time angle, our model achieves smooth generalization to the real-frequency axis. Benchmarking on the single-band Hubbard model for the Bethe
lattice demonstrates quantitative accuracy across metallic, strongly correlated, and insulating regimes.
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All authors Fenglin Deng, Yi Lu, Xiaodong Cao, Zhicheng Zhong
Materials Science
Composition-Dependent Properties of $\mathrm{Ce_{x}La_{0.95-x}Tb_{0.05}F_{3}}$ Nanopowders Tailored for X-Ray Photodynamic Therapy and Cathodoluminescence Imaging
Xenie Lytvynenko, Marie Urbanová, Ondřej Lalinský et al. (+4 more)
This study investigates the synthesis and luminescence behavior of $\mathrm{Ce_{x}La_{0.95-x}Tb_{0.05}F_{3}}$ nanoparticles with varying $\mathrm{Ce^{3+}}$ content. The materials were prepared via a wet chemical route and thermally annealed to improve crystallinity and reduce defects. Phase composition and structural parameters were examined by X-ray diffraction (XRD), while elemental composition was determined by X-ray fluorescence (XRF). Cathodoluminescence (CL) intensity mapping was used to evaluate emission uniformity and monitor the degradation of luminescence under electron beam exposure. Photoluminescence (PL) and radioluminescence (RL) spectroscopy confirmed energy transfer from $\mathrm{Ce^{3+}}$ to $\mathrm{Tb^{3+}}$ ions. Luminescence intensities were found to depend strongly on both Ce content and thermal treatment. The results contribute to the understanding of defect-related quenching mechanisms and are relevant for the design of rare-earth-based luminescent nanomaterials for biomedical applications.
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All authors Xenie Lytvynenko, Marie Urbanová, Ondřej Lalinský, Vilém Vojta, Jan Bárta, Lenka Prouzová Procházková, Václav Čuba
Materials Science · Cross-listed from physics.optics
Reflectivity-based refractive index measurement of van der Waals materials
Xavier Zambrana-Puyalto, Alexander Johan Olsen and Søren Raza
We present a reflectivity-based method for measuring the in-plane refractive index of transparent van der Waals (vdW) materials. The approach enables the characterization of as small as $3 \times 3$~{\textmu}m$^2$ exfoliated flakes on a non-transmissive substrate without assuming any specific spectral shape of the refractive index. Exfoliated flakes are most commonly obtained through mechanical exfoliation, which generally produces vdW flakes with tens-of-micron lateral dimensions. As a result, conventional ellipsometry - which depends on large, uniform areas and specific spectral models - becomes challenging to apply. Our method determines the refractive index directly from the spectral position of reflectivity minima, provided the flake thickness and the substrate complex refractive index are known. We demonstrate the technique on hafnium disulfide (HfS$_2$), a vdW
semiconductor with high refractive index and low absorption, retrieving its in-plane refractive index across the visible range. The results both validate previous ellipsometry measurements and establish this method as an accessible and spectral-model-free alternative for refractive index characterization of vdW materials.
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Mesoscale and Nanoscale Physics
Observation of the surface hybridization gap in the electrical transport properties of the ultrathin topological insulator (Bi$_{1-x}$Sb$_{x}$)$_2$Te$_3$
Feike van Veen, Sofie Kölling, Stijn R. de Wit et al. (+4 more)
We study the three-dimensional topological
insulator (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ in its ultrathin limit i.e. when the thickness is of the same order as the surface state penetration depth. It is expected that in this limit a hybridization gap opens at the Dirac point, which gives rise to a
quantum spin Hall (QSH) or insulating phase, depending on the material thickness. We fabricate (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$
Hall bars with a thicknesses of 6 and 9 nm and measure an insulating phase around the Dirac point for low bias and at sub-Kelvin temperatures only in samples fabricated from the 6 nm films, which indicates the presence of a hybridization gap. The effect of a perpendicular
magnetic field on the hybridization gap is studied but remains partially unresolved. The results form an important step towards experimentally realizing the
quantum spin Hall state via hybridization in ultrathin films of (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$, yet, they also expose a knowledge gap regarding transport measurements in these systems.
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All authors Feike van Veen, Sofie Kölling, Stijn R. de Wit, Roel Metsch, Daniel Rosenbach, Chuan Li, Alexander Brinkman
Materials Science · Cross-listed from cs.LG
MiAD: Mirage Atom Diffusion for De Novo Crystal Generation
Andrey Okhotin, Maksim Nakhodnov, Nikita Kazeev et al. (+3 more)
In recent years,
diffusion-based models have demonstrated exceptional performance in searching for simultaneously stable, unique, and novel (S.U.N.) crystalline materials. However, most of these models don't have the ability to change the number of atoms in the
crystal during the generation process, which limits the variability of model sampling trajectories. In this paper, we demonstrate the severity of this restriction and introduce a simple yet powerful technique, mirage infusion, which enables
diffusion models to change the state of the atoms that make up the
crystal from existent to non-existent (mirage) and vice versa. We show that this technique improves model quality by up to x2.5 compared to the same model without this modification. The resulting model, Mirage Atom
Diffusion (MiAD), is an equivariant joint
diffusion model for de novo
crystal generation that is capable of altering the number of atoms during the generation process. MiAD achieves an 8.2% S.U.N. rate on the MP-20
dataset, which substantially exceeds existing state-of-the-art approaches. Code: https://github.com/andrey-okhotin/miad.git
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All authors Andrey Okhotin, Maksim Nakhodnov, Nikita Kazeev, Mikhail Lazarev, Andrey E Ustyuzhanin, Dmitry Vetrov
Mesoscale and Nanoscale Physics
Spintronics in antiferromagnetic helix: A new prescription
Suparna Sarkar and Santanu K. Maiti
The occurrence of a finite mismatch between the up and down
spin energy channels due to the application of an electric field, leading to the generation of a polarized
spin current from an unpolarized beam in
antiferromagnetic materials, has already been established. But, in this work, we report for the first time that even in the absence of any electric field,
spin polarization can be achieved. We choose a tight-binding
antiferromagnetic helix, where the strengths of
magnetic moments at different
lattice sites are non-uniform. The non-uniformity is introduced in two distinct forms, correlated and uncorrelated, and in each case we find a high degree of
spin polarization. The Greens formalism is used to compute the results under various input conditions, and the results are valid for a broad range of physical parameters. Our analysis can open up a new direction of getting
spin selectivity in different
magnetic systems with zero net magnetization, in the absence of an electric field.
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Soft Condensed Matter
Inertial active particles in a Poiseuille flow: negative mobility and particle separation
Ankit Gupta and P. S. Burada
The diffusive behavior of small entities is strongly influenced by the flow of the surrounding medium, which is ubiquitous in natural and artificial environments. In this study, we investigate the transport characteristics of the inertial active Brownian particles (ABPs) in a microfluidic channel under a Poiseuille flow. The interplay between the inertia of the particles and the imposed fluid flow leads to interesting diffusive behaviors. For instance, in the overdamped regime ($m \to 0$), particles exhibit a negative average velocity $\langle v \rangle$ due to upstream movement. As $m$ increases, particles tend to move along the flow direction with an increase in $\langle v \rangle$ in the positive direction, exhibiting a maximum at optimal $m$, and diminish for higher $m$ values. The effective
diffusion coefficient $D_{eff}$ also shows a peak at this optimal $m$. Interestingly, at higher $m$ values, $D_{eff}$ decreases with increasing the noise strength. The self-propelled velocity of the particles further enhances the upstream movement. Further, the rotation rate of the particles also contributes positively to the upstream motion, and enhances the
diffusion of the particles by many orders in the limit of higher $m$. This study reveals that inertia not only modifies swimmer flow interactions but also enables new dynamical regimes, where mass-dependent trajectories can be harnessed for selective control. Such control holds promise for mass based particle separation in precisely engineered environments and lab on a chip devices for technological applications.
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Mesoscale and Nanoscale Physics
Scaling of Low-Temperature Heat Capacity in Cryocrystals
M. Barabashko, A. Jeżowski and A. Krivchikov
The low-temperature isochoric heat capacity of cryocrystals was scaled using the universal scaling function. This universality links the magnitude of the anomaly and the characteristic temperature of the hump $T_{\mathrm{max}}$ in heat capacity, which is related to the first van Hove singularity in the
phonon spectrum. For atomic, molecular, and
quantum cryocrystals, $T_{\mathrm{max}}$ systematically shifts with molar volume, reflecting Brillouin zone scaling and revealing a common vibrational origin. These findings for the scaling function bridge thermodynamics with the vibrational density of states, highlighting fundamental universality in
lattice dynamics.
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Mesoscale and Nanoscale Physics
Shape dependence of Edelstein and magnetoelectric effects in the V-shaped model
Shuhei Kanda and Satoru Hayami
We theoretically investigate the shape dependence and microscopic mechanism of the magnetoelectric (ME) effect, including both nonmagnetic (Edelstein-type) and
magnetic origins, in a V-shaped one-dimensional chain model. Numerical calculations based on the Kubo formula reveal that the nonmagnetic-driven ME response is maximized at an apex angle of $\theta \approx 0.6\pi$. To clarify its origin, we derive a low-energy effective
Hamiltonian in the $s$-orbital subspace and demonstrate that the polarity induced by the V-shaped geometry manifests as an effective
spin–orbit interaction. An analytical derivation of the Green's function shows that the
geometric effect can be described as a $T$-
matrix contribution associated with local
symmetry breaking. This scattering-theoretical representation enables us to identify the contributions of local
geometric symmetry breaking to the ME response. Using a multipole-basis representation, we identify
symmetry-based selection rules for the ME tensor and show that the coupling between the effective
spin–orbit interaction and the orbital angular momentum generated across the apex plays an essential role. The resulting angular dependence, $\sin{\theta}\sin{\theta/2}$, peaks at $\theta = 2\tan^{-1}\sqrt{2} \approx 0.608\pi$, in good agreement with the numerical results. We also analyze a
ferromagnetic V-shaped model including the Zeeman interaction and show that the
magnetic-driven ME response originates from the
spin magnetization induced by the coupling between the electric-field–driven charge-potential gradient and the Zeeman term. These results reveal distinct ME mechanisms depending on the presence or absence of time-reversal
symmetry and clarify the microscopic origin of shape-dependent ME responses in V-shaped chains.
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Statistical Mechanics
On the First Quantum Correction to the Second Virial Coefficient of a Generalized Lennard-Jones Fluid
Daniel Parejo and Andrés Santos
We derive an explicit analytic expression for the first
quantum correction to the second virial coefficient of a $d$-dimensional fluid whose particles interact via the generalized Lennard-Jones $(2n,n)$ potential. By introducing an appropriate change of variable, the correction term is reduced to a single integral that can be evaluated in closed form in terms of
parabolic cylinder or generalized Hermite functions. The resulting expression compactly incorporates both dimensionality and stiffness, providing direct access to the low- and high-temperature asymptotic regimes. In the special case of the standard Lennard-Jones fluid ($d=3$, $n=6$), the formula obtained is considerably more compact than previously reported representations based on hypergeometric functions. The knowledge of this correction allows us to determine the first
quantum contribution to the Boyle temperature, whose dependence on dimensionality and stiffness is explicitly analyzed, and enables quantitative assessment of
quantum effects in noble gases such as helium, neon, and argon. Moreover, the same methodology can be systematically extended to obtain higher-order
quantum corrections.
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Statistical Mechanics · Cross-listed from math.PR
Stationary inverse-Wishart polymers
Guillaume Barraquand and Zikun Ouyang
A solvable model of directed
polymer with
matrix-valued disorder is introduced in arXiv:2203.14868. The disorder is made of $d\times d$ inverse-Wishart random
matrices, so that the model nicely generalizes the well-studied log-gamma
polymer, recovered when $d=1$. Much of the features of the log-gamma
polymer seem to have analogues for higher $d$, although the integrability needs to be better understood. In this paper, we introduce stationary inverse-Wishart
polymer models on a quadrant or a strip of $\mathbb Z^2$. In each setting, we identify stationary measures, characterized explicitly in terms of random walks with inverse-Wishart increments in special cases, or more complicated two-layer Gibbs measures for generic choices of boundary parameters. We also make
conjectures about asymptotics of the free energy, and explain important differences between
matrix-valued
polymer models and their scalar counterpart, due to non-commutativity.
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Materials Science · Cross-listed from quant-ph
Quantum Biology, Quantum Simulation and Quantum Coherent Devices
Rong-Hang Chen, Jing Dong, Wen Yang et al. (+2 more)
Many living organisms can exploit
quantum mechanical effects to gain distinct biological advantages. In plants, photosynthesis uses
quantum coherence to achieve near 100% efficiency in energy transfer. With advances in experimental techniques, two-dimensional electronic spectroscopy can reveal dynamic processes such as coherence and coupling within a system, and it plays an important role in studying energy transfer in photosynthesis. On the theory side, methods such as the generalized Bloch-Redfield theory and the hierarchical equations of motion are used to model photosynthetic systems.
Quantum simulation, as a high-efficiency and low-complexity approach, has also made progress across various platforms in the study of photosynthesis. In recent years, a series of studies has introduced
quantum coherence into artificial systems to enhance energy transfer efficiency, laying the groundwork for the design of coherent devices with efficient energy transport. Birds can use the weak geomagnetic field and
spin-dependent chemical reactions to detect direction. Theoretical frameworks for animal
navigation include magnetite-based mechanisms, magnetoreceptor genes, and the radical-pair mechanism.
Quantum simulations of
navigation have also advanced on multiple platforms. Inspired by animal
navigation, diverse
quantum effects have been applied to improve sensing and to support
navigation tasks. This paper presents a comprehensive review of progress on
quantum coherence in photosynthesis and avian
navigation, along with related theoretical methods,
quantum simulation approaches, and research on
quantum coherent devices.
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All authors Rong-Hang Chen, Jing Dong, Wen Yang, Qing Ai, Gui-Lu Long
Statistical Mechanics
Hybrid ab initio and empirical machine learning models for the potential energy surface
Pablo Peña-Cano and Pablo M. Piaggi
We propose a methodology to generate hybrid machine learning models for the potential energy surface trained simultaneously on data from ab initio electronic structure calculations and on thermodynamic and/or structural observables from experiment. The approach is based on the use of a loss function that includes the mean square error of observables with respect to their experimental values, in addition to the usual terms involving the mean square error of the energies and forces with respect to ab initio data. We employ a reweighting procedure that allows for the calculation of ensemble averages of observables during training for arbitrary values of the model parameters and on the fly. The method is general and can be applied to any set of static observables. We illustrate the usefulness of this approach by applying it to the generation of hybrid models for
liquid water that reproduce accurately the experimental density maximum, the density isobar at 1 bar, and the radial distribution function in molecular dynamics simulations.
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Statistical Mechanics
Numerical analysis of heat transport in classical one-dimensional systems
Antonio Politi
Numerical studies of some unidimensional systems suggest that
Fourier law is satisfied, where theory predicts a divergence of heat conductivity with the system size. Here, I revisit some such models, finding that in all cases a divergence asymptotically emerges. This includes a variant of the ding-a-ling model, where I find that, contrary to previous claims, the “anomalous" growth starts already for moderate system sizes. More conceptually interesting is the case of non-binding potentials, whose behavior is well reproduced by assuming that the energy flux across the nonequilibrium stationary state is the sum of two contributions: a diffusive and a hydrodynamic one. This approach, which extends an idea previously formulated for nearly integrable systems, allows to conclude that the asymptotic regime is always dominated by the anomalous hydrodynamic component, but the crossover may occur for extremely long system sizes.
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Superconductivity
Fast-driving spectroscopy of current-phase relationships of individual Josephson elements
Maxim Tjøtta, Devashish Shah, Kanishk Modi et al. (+4 more)
Extracting the current-phase relationship (CPR) of a single superconducting junction is challenging in practice and traditionally involves
embedding the junction in a larger superconducting
circuit containing SQUIDs and/or resonators. Applying ac driving to the junction has proven to be a viable and less invasive way to extract information about the few lowest harmonics of the CPR, by locating the integer and fractional Shapiro steps in the IV-curve of the driven junction. Here, we present an alternative driving-based method that allows to extract the full harmonic content of a CPR in a relatively non-invasive way, by fitting the measured critical currents of the driven junction as a function of driving power. We test our method, both using numerical simulations and in experiments, and we show that it works accurately.
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All authors Maxim Tjøtta, Devashish Shah, Kanishk Modi, Marco Valentini, Rubén Seoane Souto, Georgios Katsaros, Jeroen Danon
Materials Science
Two-component anomalous Hall and Nernst effects in anisotropic Fe$_{4-x}$Ge$_x$N thin films
R.K. Paul, J. Vít, P. Levinský et al. (+18 more)
A series of thin films Fe$_{4-x}$Ge$_x$N (x=0-1) was fabricated onto MgO substrates by magnetron sputtering with the aim of studying the possible enhancement of the anomalous Nernst effect (ANE), envisaged based on Density Functional Theory (DFT) calculations. The Nernst and
Hall effects of the series were systematically analyzed, complemented with resistivity,
magnetic, electron microscopy and Mössbauer experiments, and DFT calculations including elastic properties. The Fe$_4$N phase crystallizes in the cubic
symmetry with Pm3m space group, whereas a small tetragonal distortion is realized in for x>0.35. From the comparison of the experimental isomer shift with DFT calculations, we conclude that Ge occupies the 4b site in the tetragonal I4/mcm tructure.
Ferromagnetic T$_C$ decreases rapidly from 750 K for x=0 to 100 K for x=1. The tetragonal samples with x=0.8 and 1 display two-component behavior in the
Hall and Nernst effects hysteresis loops, which can be analyzed as a sum of positive and negative loops with different saturation fields. This unusual behavior is a product of a combination of several factors. (1) Co-existence of two different crystallographic orientations in the tetragonal thin film, namely with the majority of c-axis and minority of a-axis normal to the film surface. (2) Opposite sign of the anomalous
Hall and Nernst effects for the direction of magnetization along the a and c-axis revealed by DFT calculation. (3) The magnetocrystalline anisotropy characterized by an easy ab-plane, which is responsible for the different saturation fields for a and c-axis. The maximum ANE was determined to be 0.9 $\mu$V/K for x=0 at room temperature, and -0.85 $\mu$V/K for x=1 at T=50 K. The rapid increase of ANE of Fe$_3$GeN from low temperatures indicates that, were it not for its low T$_C$, it could surpass ANE of Fe$_4$N.
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All authors R.K. Paul, J. Vít, P. Levinský, J. Hejtmánek, O. Kaman, M. Pashchenko, L. Kubíčková, K. Ahn, M. Jarošová, J. More Chevalier, S. Cichoň, T. Kmječ, J. Kohout, M. Hans, S. Mráz, J.M. Schneider, E. Adabifiroozjaei, L. Molina-Luna, O. Gutfleisch, I. Dirba, K. Knížek
Materials Science · Cross-listed from physics.optics
Record Index-Bandgap Trade-off: CdPS3 as a High-Index van der Waals Platform for Ultraviolet-Visible Nanophotonics
M. R. Povolotskiy, A. S. Slavich, G. A. Ermolaev et al. (+21 more)
The development of nanophotonics is hindered by a fundamental trade-off between a material's refractive index (n) and its electronic bandgap (Eg), which severely restricts the choice of materials for short-wavelength applications. This challenge is particularly acute in the visible and ultraviolet (UV) spectra, where high-performance devices require materials that are simultaneously highly refractive and transparent. Here, we report on the van der Waals (vdW)
crystal cadmium phosphorus trisulfide (CdPS3) as a solution to this long-standing problem. Through comprehensive optical and structural characterization, we show that CdPS3 possesses an anomalously high in-plane refractive index across the visible spectrum approaching 3 in the near-UV, combined with a wide indirect bandgap. This combination of properties, which circumvents the empirical Moss's law, is validated by first-principles calculations and direct near-field imaging of highly confined waveguide modes. These findings establish CdPS3 as a leading material for UV-visible photonics, opening a new pathway for the development of high-density integrated
circuits and metasurfaces.
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All authors M. R. Povolotskiy, A. S. Slavich, G. A. Ermolaev, D. V. Grudinin, N. V. Pak, I. A. Zavidovskiy, K. V. Kravtsov, A. A. Minnekhanov, M. K. Tatmyshevskiy, A. V. Syuy, D. I. Yakubovsky, A. Mazitov, L. A. Klimova, A. N. Toksumakov, A. V. Melentev, E. Zhukova, D. A. Ghazaryan, G. Tselikov, I. Kruglov, S. M. Novikov, A. A. Vyshnevyy, A. V. Arsenin, K. S. Novoselov, V. S. Volkov
Soft Condensed Matter
Molecular dynamics simulations reveal internal tension in native state collagen fibrils
Konstantinos Steiakakis, Alan Pichard and Maxime Vassaux
Collagen fibrils are the building block of many biological tissues, which viability depend on the fibrils properties. Altered properties of collagen fibrils are central to the appearance of many diseases, while physiological or native properties must be reproduced for tissue engineering. Yet, the self-assembly, the structure, and therefore the properties of collagen fibrils remain elusive. One main reason is the extreme sensitivity of the fibrils to their environmental conditions, and in particular hydration which is only loosely bound by experimental measurements. Furthermore, mechanics are an integral part of the self-assembly process; forces exerted by
cells or osmotic pressure may result in internal stresses in collagen fibrils in native conditions. Here, we propose to investigate internal stresses in collagen fibrils by means of molecular dynamics simulations of the collagen microfibril model. Our simulations reveal the quantitative
evolution of internal stresses in collagen fibrils with hydration. We establish a value of native hydration of collagen fibrils at 0.78 g/g based on an absence of cross-sectional stresses. In turn, we determine a quantitative estimate of internal longitudinal stresses in collagen fibrils in native conditions of 210 MPa. We find that internal longitudinal stresses are caused by an over-extended
protein backbone rather than partial hydration, which appears remnant of the local forces driving collagen self-assembly. We also demonstrate the consequences of internal longitudinal stresses on the mechanical properties of collagen fibrils, which the absence of induces more than a 20% decrease in the Young's modulus. Overall, our findings provide insights into the native structure and properties of collagen fibrils. More than ever, collagen fibrils appear to be assembled via an out-of-
equilibrium process key to the synthesis of viable tissues.
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Quantum Gases
Stability of current-carrying states in hard-core bosons with long-range hopping on a square lattice
Yoshihiro Yabuuchi and Ippei Danshita
We investigate the stability of current-carrying states with quasi-momentum $K$ in the Bose-condensed phase of the hard-core Bose-Hubbard model on a square
lattice, where particles transfer between two sites separated by distance $r$ with hopping amplitude decaying algebraically with $r$ as $\propto r^{-\alpha}$. Using a mean-field theory, we analyze the excitation spectrum and determine the critical quasi-momenta associated with Landau and dynamical instabilities. We find that the long-range hopping suppresses the critical quasi-momenta and makes them vanish at $\alpha=3$. Near $\alpha=3$, we show that the critical quasi-momentum $K_{\mathrm{c}}$ for the dynamical instability exhibits the scaling behavior $K_\mathrm{c} \propto \Delta^{1+\Delta}$ with $\Delta=\alpha-3$, where the scaling exponent explicitly depends on $\Delta$, as a consequence of the long-range nature of the hopping.
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Materials Science
Heat Capacity of Thermally Reduced Graphene Oxide: Compaction and Thermal Annealing Effects
A.I. Krivchikov, A. Jezowski, M.S. Barabashko et al. (+8 more)
We present a comprehensive investigation of the low-temperature heat capacity of thermally reduced
graphene oxide (trGO) as a function of compaction pressure and annealing temperature.
Graphene oxide was synthesized using a modified Hummers method and subsequently thermally reduced at 300\,{\deg}C, 500\,{\deg}C, and 700\,{\deg}C under
vacuum to systematically vary the oxygen content and structural ordering. The specific heat data in the 2–300\,K range reveal that the thermal response is governed by
phonons, including contributions from a Schottky-type anomaly, a defect-related linear term, a Debye term, and a dispersive term with a negative coefficient associated with out-of-plane flexural (ZA)
phonons. Increasing compaction pressure alters interlayer coupling and leads to non-monotonic changes in heat capacity, while higher annealing temperatures enhance graphitization, reduce disorder, and modify
phonon dispersion. The absence of a
boson peak – similar to that observed in carbon nanotubes – supports the dominance of two-dimensional vibrational modes. These findings elucidate the relationship between dimensionality, structural disorder, and processing parameters in shaping the
phonon dynamics of trGO, providing guidance for tailoring its thermal behavior in advanced carbon-based functional materials.
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All authors A.I. Krivchikov, A. Jezowski, M.S. Barabashko, A.V. Dolbin, N.A. Vinnikov, S.V. Cherednichenko, Yu. Horbatenko, O. Korolyuk, O. Bezkrovnyi, O. Romantsova, D. Szewczyk
Materials Science
Current Switching of Topological Spin Chirality in the van der Waals Antiferromagnet Co1/3TaS2
Kai-Xuan Zhang, Seungbok Lee, Woonghee Cho et al. (+1 more)
Magnetic topology is central to modern
quantum magnet, where
spin chirality governs exotic
spin winding, real-space Berry phase, and topological
Hall effect. A key unresolved challenge is how to electrically switch topological
spin chirality and its associated gauge flux, an essential requirement for manipulating its topological
quantum properties. In this work, we propose and experimentally demonstrate the concept of current-switching
spin chirality. We identify the new vdW antiferromagnet Co1/3TaS2 as an ideal platform, hosting a topological 3Q state with a minimum chirality
cell, an ultrahigh skyrmion density, a non-centrosymmetric geometry, and a strong Berry
curvature. We discover intrinsic self-torque-induced chirality switching within Co1/3TaS2, driven purely by current, without the need of heavy metals or a
magnetic field, and with high energy efficiency. Our results establish a promising framework for electrically generating and controlling topological
spin chirality, and demonstrate a practical route toward
chiral spintronics. They can be naturally generalised to other skyrmion systems, offering new opportunities in
symmetry control, topological manipulation, and
spin-chirality-based
quantum functionalities.
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All authors Kai-Xuan Zhang, Seungbok Lee, Woonghee Cho, Je-Geun Park
Materials Science
Integrating electronic structure into generative modeling of inorganic materials
Junkil Park, Junyoung Choi and Yousung Jung
Recent advances in generative models have introduced a new paradigm for the inverse design of inorganic materials, enabling the discovery of new crystalline structures with desired properties. However, existing generative models focus solely on structural aspects of materials during generation, while overlooking the underlying electronic behavior that fundamentally governs materials' stability and functionality. In this work, we present ChargeDIFF, the first generative model for inorganic materials that explicitly incorporates electronic structure into the generation process. Specifically, ChargeDIFF leverages charge density, a direct spatial representation of a material's electronic structure, as an additional modality for generation. ChargeDIFF demonstrates exceptional performance in both unconditional and conditional generation tasks compared to baseline models, with ablation studies revealing that this improvement is directly due to its ability to capture the material's electronic structure during generation. Moreover, the ability to control charge density during generation allows ChargeDIFF to introduce a novel inverse design method based on three-dimensional charge density, illustrating the potential to generate lithium-ion battery cathode materials with desired ion migration pathways, as validated by physics-based simulations. By highlighting the importance of accounting for electronic characteristics during material generation, ChargeDIFF offers new possibilities in the generative design of stable and functional materials.
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Quantum Gases · Cross-listed from physics.atom-ph
Magnetic atoms with a large electric dipole moment
Johannes Seifert, Sid C. Wright, Boris G. Sartakov et al. (+2 more)
We experimentally show that an electric dipole moment of more than 1 Debye can be induced in the dysprosium (Dy) atom, in a long-lived state that is about 17513 cm$^{-1}$ above the ground state. This metastable state is part of a strongly coupled opposite-parity doublet. Using optically detected microwave spectroscopy in an atomic beam, we determine the approximately 1.12 cm$^{-1}$ doublet spacing for the five stable bosonic isotopes of Dy with kHz-level accuracy. From the shift of the microwave transition frequency in low electric fields (below 150 V/cm) and from optical spectra in high electric fields (up to 150 kV/cm), a reduced transition dipole moment of 7.65 $\pm$ 0.05 Debye between the doublet states is extracted. In high electric fields the doublet interacts with a third state at 17727 cm$^{-1}$, that connects to the ground state via an electric-dipole transition. The three-state Stark interaction enables preparation of Dy atoms in the metastable state via single-
photon excitation from the ground state.
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All authors Johannes Seifert, Sid C. Wright, Boris G. Sartakov, Giacomo Valtolina, Gerard Meijer
Disordered Systems and Neural Networks
Strongly Electric Field Dependent Conductivity in Quantum Dot Solids
Morteza Shokrani, Xinlu Wu, Ebbo Krahmer et al. (+1 more)
Charge transport in QD solids is typically understood as thermally activated tunneling or hopping between states that are localized on individual QDs. Here, we show that the slow relaxation that is associated with the disorder-broadened density of (localized) states leads to a strong electric field F dependence of the charge carrier mobility. We interpret the results in terms of an increased effective electronic temperature T_eff that exceeds that of the
lattice. We use a heat balance model to derive an analytical expression for T_eff (F) that is similar to, and puts a physical basis under the phenomenological expression proposed by Marianer and Shklovskii [Phys. Rev. B 46, 13100 (1992)]. We apply this model to analyze the field- and temperature-dependent conductivity in ZnO QDs with varying ligand length and depletion shell thickness and find (effective) localization lengths ranging from 2 to 5 nm. Both experimental and analytical results compare favorably to numerical simulations by kinetic Monte Carlo. Due to the large value of the effective localization length, the field dependence already becomes relevant at modest fields around 1-10 V/micron, that are typical for operational conditions of photovoltaic and light emitting devices based on
quantum dot solids.
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All authors Morteza Shokrani, Xinlu Wu, Ebbo Krahmer, Martijn Kemerink
Quantum Gases
Mass-imbalance effect on the cluster formation in a one-dimensional Fermi gas with coexistent $s$- and $p$-wave interactions
Yixin Guo
We consider the mass-imbalance effect on the clustering in a one-dimensional two-component
Fermi gas with coexistent even- and odd-wave interactions resulting in different configurations of clustering phases. We obtain the solutions of both stable two- and three-body cluster states with different mass ratios and configurations by solving the corresponding variational equations. We numerically map out phase diagrams consisting of the $s$- and $p$-wave pairing phases, and {trimer} phase with different configurations, in a plane of $s$- and $p$-wave pairing strengths. Within the explored ranges of $s$- and $p$-wave pairing strengths, the in-
vacuum three-body states are always more deeply bound than the two-body ones. While for the in-medium case, the Cooper {trimer} phase dominates over the pairing phases when both $s$- and $p$-wave interactions are moderately strong. There is also a competition between different clustering configurations of three-body clustering.
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Mesoscale and Nanoscale Physics
Chemical vapor deposition growth of continuous monolayer antiferromagnetic CrOCl films
Chao Chen, Yulu Liu, Hongyan Lu et al. (+29 more)
The discovery of two-dimensional
magnetic materials has provided an ideal platform for exploring physical phenomena in the two-dimensional limit. However, intrinsic two-dimensional
antiferromagnetic materials have been rarely reported, limiting systematic studies of their electronic properties. The discovery of novel intrinsic two-dimensional antiferromagnets and the development of robust synthesis strategies, therefore, remain significant challenges. Here, we report the chemical vapor deposition synthesis of CrOCl monolayer films and nanosheets that exhibit excellent air stability. The CrOCl morphology is tunable, ranging from two-dimensional nanosheets to three-dimensional flower-like structures, with lateral sizes ranging from several microns to continuous monolayer films. Structural characterization confirms the materials composition and high crystalline quality. Furthermore,
magnetic measurements, supported by theoretical calculations, reveal a Néel temperature for CrOCl of ~14 K. This work provides a reliable route for preparing two-dimensional
antiferromagnetic materials.
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All authors Chao Chen, Yulu Liu, Hongyan Lu, Zihao Wang, Bowen Zheng, Qian Guo, Jingkuan Xiao, Ping Wang, Wanting Xu, Yulin Han, Mingxuan Chen, Xiaofan Cai, Jiabei Huang, Yaqing Han, Di Zhang, Renjun Du, Alexander S. Mayorov, Ziying Li, Shuai Zhang, Yi Huang, Tingting Cheng, Zhaolong Chen, Ronghua Liu, Nujiang Tang, Haibo Ni, Di Wu, Libo Gao, Xiaoxiang Xi, Qianghua Wang, Lei Wang, Kostya S. Novoselov, Geliang Yu
Disordered Systems and Neural Networks
Topological transition induced by selective random defects on a honeycomb lattice
Sogen Ikegami, Kiyu Fukui, Shun Okumura et al. (+2 more)
We investigate how the spectral and topological properties of electron systems evolve on a
lattice that interpolates between the honeycomb and its 1/6-depleted structures through the introduction of selective random defects. We find that in certain parameter regimes, the topological properties of the two
lattice systems are smoothly connected, whereas in other regimes, selective random defects induce a topological transition. Analysis based on an effective model reveals that the effect of selective random defects can be understood as a modulation of hopping amplitudes. Our results highlight the potential for designing and controlling the spectral and even topological properties of electronic systems across a wide range of material platforms.
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All authors Sogen Ikegami, Kiyu Fukui, Shun Okumura, Yasuyuki Kato, Yukitoshi Motome