Soft Condensed Matter
Thickness of epithelia on wavy substrates: measurements and continuous models
Nicolas Harmand, Julien Dervaux, Christophe Poulard et al. (+1 more)
We measured the thickness of MDCK epithelia grown on substrates with a sinusoidal profile. We show that while at long wavelength the profile of the epithelium follows that of the substrate, at short wavelengths
cells are thicker in valleys than on ridges. This is reminiscent of the so-called {\guillemotleft} healing length {\guillemotright} in the case of a thin
liquid film wetting a rough solid substrate. We explore the ability of continuum mechanics models to account for these observations. Modeling the epithelium as a thin
liquid film, with surface tension, does not fully account for the measurements. Neither does modeling the epithelium as a thin incompressible elastic film. On the contrary, the addition of an apical active stress gives satisfactory agreement with measurements, with one fitting parameter, the ratio between the active stress and the elastic modulus.
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All authors Nicolas Harmand, Julien Dervaux, Christophe Poulard, Sylvie Hénon
Soft Condensed Matter
Active polymers translocate faster in confinement
K. R. Prathyusha, Paulami Sarkar, Justin Xu et al. (+1 more)
Living organisms employ diverse strategies to navigate confined environments. Inspired by translocation observations on California blackworms (Lumbriculus variegatus), we combine biological experiments and active-
polymer simulations to examine how confinement and stiffness govern translocation. Active filaments translocate fastest when the channel width is comparable to their diameter, with escape time determined by propulsion speed, filament length, and channel geometry. In wider channels, activity and flexibility induce reorientation-dominated conformational changes that prolong escape. A single dimensionless ratio linking confinement to stiffness captures the transition from axis-aligned escape with short wall deflections for stiffer filaments, to reorientation-controlled motion with blob-like shapes for flexible filaments. These results provide a unified physical framework for active translocation in confinement and suggest design principles for flexible robotic filaments in complex environments.
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All authors K. R. Prathyusha, Paulami Sarkar, Justin Xu, Saad Bhamla
Other Condensed Matter
The advancement of Brillouin Light Scattering with the assistance of nanoplasmonic structures. Enhancement and amplification
E. Bortchagovsky, A.V. Chumak and V. Lozovski
Brillouin light scattering (BLS) is a key technique in studying magnonic systems, but its sensitivity is often limited. While nanoplasmonic systems can enhance BLS through near-field effects, we propose a novel approach for additional amplification. In this conceptual paper, we show how to actively supply energy to a surface collective electromagnetic resonance (SCR) supported by a sparse layer of metal nanoparticles on a
magnetic film. Proposed methods are designed to significantly amplify the efficiency of surface-enhanced Brillouin light scattering without increasing the intensity of the primary excitation. In the proposed scheme, the pump extends the propagation length of the SCR, leading directly to BLS amplification. We analyze the conditions for such amplification, with numerical estimates indicating a potential gain of more than an order of magnitude in the surface-wave amplitude. This gain far surpasses the modest increase achievable through passive enhancement alone. These findings outline a practical pathway to achieving BLS amplification in integrated magnonic platforms. The feasibility of the proposed approaches is discussed in light of recent experimental and theoretical advances in plasmonics, magneto-plasmonics, and magnonics.
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Soft Condensed Matter
Curvature instability of an active gel growing on a wavy membrane
Kristiana Mihali, Dennis Wörthmüller and Pierre Sens
Cell shape changes are largely controlled by the actin cytoskeleton, a dynamic filament network beneath the
plasma membrane. Several
cell types can form extended free-standing protrusions not supported by an extracellular substrate or
matrix, and regulated by
proteins that modulate cytoskeletal dynamics in a way sensitive to the
curvature of the
cell membrane. We develop a theoretical model for the mechanics of a free-standing viscous actin network growing on a corrugated membrane. The model couples the dynamics of the viscous active gel with membrane deformation and the recruitment of
curvature-sensitive actin nucleators. We show that an actin layer polymerising uniformly on the membrane always exerts a stabilising effect that reduces membrane deformation. However,
curvature-sensitive actin nucleator
proteins can render the membrane linearly unstable, depending on the interplay between membrane and actin dynamics, giving rise to spontaneous membrane deformation which could initiate extended free-standing cellular protrusion.
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Materials Science
Hydrogenated Aluminum Doped Zinc Oxide as Highly Transparent and Passivating Indium-Free Recombination Junction for TOPCon-Based Bottom Cell
Gökhan Alt{\i}ner, Jons Bolding, Yiğit Mert Kaplan et al. (+4 more)
Tandem
solar cells offer a promising alternative to exceed the efficiency limits of single-junction silicon photovoltaics, yet they require high-performance recombination junctions that are transparent, passivating, and electrically efficient. Indium tin
oxide (ITO), which is conventionally used as a recombination junction material, faces challenges related to indium scarcity and sputter-induced damage. This work investigates hydrogenated aluminum-doped zinc
oxide (AZO:H) deposited by spatial atomic layer deposition (s-ALD) as a viable indiumfree alternative for TOPCon-based bottom
cells. The deposited AZO:H films demonstrate excellent transparency, exceeding 90% in the 380-1200 nm wavelength range. When applied to n-TOPCon surfaces with an AlOx capping layer, the stack achieves an outstanding passivation quality, indicated by implied open-
circuit voltage (iVoc) values up to 734 mV after annealing. The AlOx capping layer proved crucial for enhancing thermal stability by preventing hydrogen effusion at higher temperatures. While the contact resistivity was high for the 20 nm thick films tested, the combination of superior optical and passivation properties establishes spatial ALD-deposited AZO:H as a highly promising material for creating efficient and indiumfree recombination junctions in next-generation tandem
solar cells.
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All authors Gökhan Alt{\i}ner, Jons Bolding, Yiğit Mert Kaplan, Floor Souren, Hindrik de Vries, Raşit Turan, Hisham Nasser
Mesoscale and Nanoscale Physics
Giant thermal modulation via a semiconductor-superconductor photonic field-effect heat transistor
Sebastiano Battisti, Matteo Pioldi, Alessandro Paghi et al. (+5 more)
We present a groundbreaking demonstration of thermal modulation in a field-effect-controllable
semiconductor-
superconductor hybrid structure, wherein the heating mechanism is exclusively radiative. The architecture comprises two reservoirs separated by $\sim 1$ mm and interconnected via a completely non-galvanic electrical
circuit, enabling the transfer of black-body radiation from the hot to the cold reservoir. Our device utilizes a superconducting Josephson field-effect transistor to achieve
magnetic-field-free gate-tunable regulation of heat currents within the
circuit. While prior studies have indicated the potential for electrostatic modulation of thermal transport properties, our framework demonstrates a temperature modulation of up to $\sim 45$ mK, exceeding prior findings by more than an order of magnitude. Furthermore, it proves a thermal transimpedance of $\sim 20$ mK/V at a bath temperature of $30$ mK. The development of such systems holds substantial promise for advancing heat management and routing in
quantum chips and radiation sensors, as it enables precise nonlocal control of heat flow towards a designated structure, even when the heat source is distant and non-galvanically coupled.
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All authors Sebastiano Battisti, Matteo Pioldi, Alessandro Paghi, Giorgio De Simoni, Alessandro Braggio, Giulio Senesi, Lucia Sorba, Francesco Giazotto
Soft Condensed Matter
General Purpose Inverse Design of Heterogeneous Finite-Sized Assemblies
Livia A. J. Guttieres, Ryan K. Krueger, Remi Drolet et al. (+1 more)
Designing heterogeneous, self-assembling systems is a central challenge in soft matter and biology. We present a framework that uses gradient-based optimization to invert an analytical yield calculation, tuning systems toward target
equilibrium yields. We design systems ranging from simple dimers to temperature-controlled shells to polymerizing systems, achieving precise control of self- and non-self-limiting assemblies. By operating directly on closed-form calculations, our framework bypasses trajectory-based instabilities and enables efficient optimization in otherwise challenging regimes.
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All authors Livia A. J. Guttieres, Ryan K. Krueger, Remi Drolet, Michael P. Brenner
Superconductivity
Anomalous terahertz nonlinearity in disordered s-wave superconductor close to the superconductor-insulator transition
Hao Wang, Jiayu Yuan, Hongkai Shi et al. (+13 more)
Detection of the
Higgs mode in
superconductors using nonlinear terahertz spectroscopy is a key area of interest in condensed matter physics. We investigate the influence of disorder on the nonlinear terahertz response and the
Higgs mode in NbN thin films with varying Ioffe-Regel parameters ($k_Fl$). In strongly disordered films near the
superconductor-
insulator transition (SIT), we observe an anomalous third-harmonic generation (THG) signal above $T_c$, which is absent in both cleaner superconducting and non-superconducting counterparts. The persistence of this normal-state THG signal in a high
magnetic field excludes superconducting fluctuations as its origin. Below $T_c$, the THG intensity increases sharply, indicating a dominant contribution from the driven
Higgs mode. The THG spectrum of the strongly disordered sample exhibits a broadened, multi-peak structure, which we attribute to
quantum path interference between distinct channels involving unpaired electrons and Cooper pairs within emergent superconducting islands. Our findings not only demonstrate how disorder tunes the nonlinear terahertz response but also uncover a strong coupling between electrons responsible for normal-state THG and the superconducting
Higgs mode below $T_c$ in strongly disordered samples.
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All authors Hao Wang, Jiayu Yuan, Hongkai Shi, Haojie Li, Xiaoqing Jia, Xiaohui Song, Liyu Shi, Tianyi Wu, Li Yue, Yangmu Li, Kui Jin, Dong Wu, Jianlin Luo, Xinbo Wang, Tao Dong, Nanlin Wang
Materials Science
Broad-Range Tuning of Ferroelectric Switching of LaxBi1-xFeO3 Epitaxial Films via Digital Doping using Off-Axis Co-Sputtering
Katelyn Lazareno, Christopher Chae, Becky Haight et al. (+7 more)
To investigate the scope of ferroelectric behavior in La-substituted BiFeO3 films, LaxBi1-xFeO3 epitaxial films were synthesized using off-axis co-sputtering on SrTiO3(001) and DyScO3(110) substrates with a SrRuO3 bottom electrode layer. A digital-doping deposition method was used to enable precise control and continuous tuning of La concentration in high-quality LaxBi1-xFeO3 films across a wide range of x = 0.05-0.60, which was systematically investigated using piezoresponse force microscopy. Robust and reversible out-of-plane ferroelectric switching has been observed up to x = 0.35, while films with x $\geq$ 0.37 exhibit no measurable ferroelectric behavior, indicating a sharp ferroelectric-to-paraelectric phase transition between x = 0.35 and 0.37. This represents the highest reported La concentration in LaxBi1-xFeO3 films that retains ferroelectric ordering, highlighting opportunities to engineer ferroelectric and multiferroic properties in complex
oxide heterostructures.
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All authors Katelyn Lazareno, Christopher Chae, Becky Haight, Shams Jabin, Rachel Steinhardt, John J. Plombon, Siddharth Rajan, Patrick M. Woodward, Jinwoo Hwang, Fengyuan Yang
Statistical Mechanics
deGennes-Suzuki-Kubo Quantum Ising Mean Field Dynamics: Applications to Quantum Hysteresis, Heat Engines and Annealing
Soumyaditya Das, Soumyajyoti Biswas, Muktish Acharyya et al. (+1 more)
We briefly review the early development of the mean-field dynamics for cooperatively interacting
quantum many-body systems, mapped to pseudo-
spin (Ising-like) systems. We start with (Anderson, 1958) pseudo-
spin mapping of the BCS (1957)
Hamiltonian of superconductivity, reducing it to a mean-field
Hamiltonian of XY (or effectively Ising) model in a transverse field. Then we get the mean-field estimate for the
equilibrium gap in the ground state energy at different temperatures (gap disappearing at the transition temperature), which fits Landau's (1949) phenomenological theory of superfluidity. We then present in detail a general dynamical extension (for non-
equilibrium cases) of the mean-field theory of
quantum Ising systems (in a transverse field), following de Gennes' (1963) decomposition of the mean field into orthogonal classical cooperative (longitudinal) component and the
quantum (transverse) component, with each component following Suzuki–Kubo (1968) mean-field dynamics. Next we discuss its applications to
quantum hysteresis in Ising magnets (in presence of an oscillating transverse field), to
quantum heat engines (employing transverse Ising model as working fluid), and to the
quantum annealing of the Sherrington–Kirkpatrick (1975)
spin glass by tuning down (to zero) the transverse field, which provides a very fast computational
algorithm leading to ground state energy values converging to the best known analytic estimate for the model. Finally, we summarize the main results obtained and conclude about the effectiveness of the de Gennes–Suzuki–Kubo mean-field equations for the study of various dynamical aspects of
quantum condensed matter systems.
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All authors Soumyaditya Das, Soumyajyoti Biswas, Muktish Acharyya, Bikas K. Chakrabarti
Mesoscale and Nanoscale Physics
Metrics for spin-based computing
Hidekazu Kurebayashi, Giovanni Finocchio, Karin Everschor-Sitte et al. (+10 more)
Spin-based computing is emerging as a powerful approach for energy-efficient and high-performance solutions to future data processing hardware. Spintronic devices function by electrically manipulating the collective dynamics of the electron
spin, that is inherently non-volatile, nonlinear and fast-operating, and can couple to other degrees of freedom such as photonic and phononic systems. This review explores key advances in integrating
magnetic and spintronic elements into computational architectures, ranging from fundamental components like
radio-frequency
neurons/synapses and spintronic probabilistic-bits to broader frameworks such as reservoir computing and
magnetic Ising machines. We discuss hardware-specific and task-dependent metrics to evaluate the computing performance of
spin-based components and associate them with physical properties. Finally, we discuss challenges and future opportunities, highlighting the potential of
spin-based computing in next-generation technologies.
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All authors Hidekazu Kurebayashi, Giovanni Finocchio, Karin Everschor-Sitte, Jack C. Gartside, Tomohiro Taniguchi, Artem Litvinenko, Akash Kumar, Johan Åkerman, Eleni Vasilaki, Kemal Selçuk, Kerem Y. Çamsar{\i}, Advait Madhavan, Shunsuke Fukami
Soft Condensed Matter
Spontaneous rotation and propulsion of suspended capsules in active nematics
Júlio P. A. Santos, Margarida M. Telo da Gama and Rodrigo C. V. Coelho
We investigate the dynamics of elastic capsules suspended in two-dimensional active nematic fluids using
lattice Boltzmann simulations. The capsules, modeled as flexible membranes enclosing active internal regions, exhibit a rich variety of behaviors shaped by their geometry and the interplay between internal and external activity. Circular capsules with active interiors undergo persistent rotation driven by internally confined +1/2 topological defects. Axisymmetric capsules, such as boomerangs, develop directed motion along their axis of
symmetry due to unbalanced active forces generated by defect distributions near their boundaries. We further show that capsule flexibility suppresses motility and rotation, as active stresses are dissipated into shape deformations. These findings reveal how shape, deformability, and defect dynamics cooperate to produce emergent motility in soft active matter, with potential applications in the design of microswimmers and drug delivery vehicles.
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Statistical Mechanics
Conjecture on the lower bound of the length-scale critical exponent $\nu$ at continuous phase transitions
Andrea Pelissetto and Ettore Vicari
A fundamental issue in the renormalization-group (RG) theory of critical phenomena concerns the allowed values of critical exponents that are consistent with the continuous nature of a phase transition. Here we
conjecture a lower bound for the length-scale exponent $\nu$, which should hold for the large class of continuous transitions associated with $d$-dimensional Landau-Ginzburg-Wilson (LGW) $\Phi^4$ theories with a multicomponent scalar field ${\varphi}$ and a unique ${\varphi}\cdot {\varphi}$ quadratic term (including some extensions with fermionic and gauge fields), describing many universality classes of critical phenomena. If $\Delta_\varphi=(d-2+\eta)/2$ is the dimension of the order-parameter field ${\varphi}$, and $\Delta_\varepsilon=d-1/\nu$ is the RG dimension of the energy operator $\varepsilon$, which can be identified with $[{\varphi}\cdot {\varphi}]$ (the squared field with a proper subtraction of the mixing with the identity), we
conjecture the inequality $\Delta_\varepsilon \ge 2 \Delta_\varphi$, which implies $\nu \ge (2-\eta)^{-1}$ and $\gamma = (2-\eta)\nu\ge 1$. These inequalities are supported by general arguments for
ferromagnetic lattice models, by $\epsilon$-expansion results for generic LGW $\Phi^4$ theories close to four dimensions, exact relations for two-dimensional minimal conformal field theories, and are consistent with all further known (numerical, perturbative, and exact) results for LGW $\Phi^4$ theories. In particular, since unitarity requires $\eta\ge 0$, the above inequality implies $\nu\ge 1/2$ for
unitary theories. This lower bound is more restrictive than $\nu > 1/d$, derived by noting that $\nu=1/d$ characterizes the singular finite-size behavior at first-order transitions.
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Materials Science
Machine learning method to determine concentrations of structural defects in irradiated materials
Landon Johnson, Walter Malone, Jason Rizk et al. (+4 more)
The formation and subsequent growth of structural defects in an irradiated material can strongly influence the material's performance in technological and industrial applications. Predicting how the growth of defects affects material performance is therefore a pressing problem in materials science. One common computational approach that is used to examine defect growth is cluster dynamics, a method which employs a system of mean-field rate equations to track the time
evolution of concentrations of individual defect types. However, the computational complexity of performing cluster dynamics can limit its practical implementation, specifically in the context of exploring a broad set of physical conditions corresponding to, for example, different temperatures and pressures. Here, we present a machine learning approach to circumvent the computational challenges of performing cluster dynamics while maintaining high accuracy in the prediction of defect concentrations. The method is illustrated on the
nuclear material uranium nitride but is broadly applicable to other materials. The developed data-driven method is shown to accurately capture complex correlations between material properties, temperature, irradiation conditions, and the concentration of defects.
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All authors Landon Johnson, Walter Malone, Jason Rizk, Renai Chen, Tammie Gibson, Michael W. D. Cooper, Galen T. Craven
Materials Science
Design and theory of switchable linear magnetoelectricity by ferroelectricity in Type-I multiferroics
Hui-Min Zhang, Cheng-Ao Ji, Tong Zhu et al. (+5 more)
We present a comprehensive theoretical investigation of magnetoelectric (ME) coupling mechanisms in 19 altermagnetic and 4 ferrimagnetic Type-I multiferroics using electronic band structure calculations with
spin-orbit coupling, a first-principles ME response framework, and
spin-space-group theory analysis. We formulate a universal scheme for realizing nonvolatile ME coupling in Type-I multiferroics, where two distinct pathways emerge, each dictated by
spin-space
symmetry. The first pathway is associated with switching of the
spin splitting or the now familiar
spin-momentum locking in reciprocal space, characteristic of some altermagnetic mul-tiferroics that exhibit coexisting antiferromagnetism and ferroelectricity. The second pathway involves real-space magnetization switching via electric polarization reversal, characterized by switchable components of the linear ME tensor, despite the traditionally weak coupling in Type-I systems due to the independent origins of magnetism and ferroelectricity. We demonstrate that these two intrinsic ME coupling mechanisms are mutually exclusive and propose thermodynami-cally stable compounds for experimentation. Our findings establish general design principles for controlling robust nonvolatile ME effects in multiferroic materials.
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All authors Hui-Min Zhang, Cheng-Ao Ji, Tong Zhu, Hongjun Xiang, Hiroshi Kageyama, Shuai Dong, James M. Rondinelli, Xue-Zeng Lu
Materials Science
Sub-unit cell engineering of CrVO$_3$ superlattice thin films
Claudio Bellani, Simon Mellaerts, Wei-Fan Hsu et al. (+13 more)
Ordered corundum
oxides introduce new prospects in the field of functional
oxides thin films, complementing the more widely studied class of ABO$_3$ perovskites. In this work, we take advantage of the layer-by-layer growth regime to fabricate epitaxial CrVO$_3$ superlattice thin films with atomic-scale accuracy on the periodic arrangement of Cr and V layers. By means of X-ray diffraction, scanning transmission electron microscopy and Raman spectroscopy, we confirm the thickness control in the sub-unit
cell scale, alternating 3, 2 or 1 single atomic layers of Cr$_2$O$_3$ and V$_2$O$_3$. For the first time, we stabilize the ilmenite phase of CrVO$_3$ (space group R-3) and compare the functional properties of the thin film with those calculated by density functional theory. This novel approach to the growth of ordered corundum
oxides opens the path towards the stabilization of new complex
oxides with tailored properties by varying the composition and the superlattice period, ultimately broadening the family of functional rhombohedral
oxides.
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All authors Claudio Bellani, Simon Mellaerts, Wei-Fan Hsu, Koen Schouteden, Alberto Binetti, Arno Annys, Zezhong Zhang, Nicolas Gauquelin, Johan Verbeeck, Jesús López-Sánchez, Adolfo del Campo, Soon-Gil Jung, Tuson Park, Michel Houssa, Jean-Pierre Locquet, Jin Won Seo
Materials Science
On chaotic regimes of conductivity behavior in the tight-binding approximation
A.Ya. Maltsev
We investigate the probability of detecting the most nontrivial conductivity behavior regimes in metals whose electron spectrum is described by the tight-binding approximation. These regimes are associated with the emergence of highly complex electron trajectories on the
Fermi surface and correspond to a nontrivial (scaling) behavior of the conductivity tensor in strong
magnetic fields. The geometry of such trajectories, as well as the corresponding conductivity regimes, have been well studied theoretically; however, they have not yet been observed experimentally. The results of our study allow us, in particular, to estimate the probability of their occurrence and to indicate the conditions for their possible detection for a wide class of conductors.
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Statistical Mechanics
Macroscopic fluctuation-response theory and its use for gene regulatory networks
Timur Aslyamov, Krzysztof Ptaszyński and Massimiliano Esposito
Gaussian macroscopic fluctuation theory underpins the understanding of noise in a broad class of nonequilibrium systems. We derive exact fluctuation-response relations linking the power spectral density of stationary fluctuations to the linear response of stable nonequilibrium steady states. Both of these can be determined experimentally and used to reconstruct the kernel of the linearized dynamics and the
diffusion matrix, and thus any features of the Gaussian theory. We apply our theory to gene regulatory networks with negative feedback, and derive an explicit internal-external noise decomposition of the power spectral density for any networks, including cross-correlations.
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Materials Science
Chiral soft mode transition driven by strain in ferroelectric bubble domains
Urmimala Dey, Natalya S. Fedorova, Jorge Íñiguez-González et al. (+1 more)
Chirality in solids is attracting growing
attention as a potential ferroic order, yet virtually no paradigmatic example of a soft-mode achiral-to-
chiral phase transition has been firmly established to date. Here we identify ferroelectric bubble domains as a model system that undergoes a strain-driven achiral-to-
chiral transition exhibiting the hallmarks of spontaneous
symmetry breaking. Using second-principles atomistic simulations, we uncover
chiral phonon modes in ferroelectric/dielectric superlattices that soften under epitaxial strain following textbook soft-mode behaviour. The transition is accompanied by a change in topological character, highlighting an interplay between chirality and
topology in these systems. This work provides a concrete step towards establishing chirality as a genuine ferroic order in solids.
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All authors Urmimala Dey, Natalya S. Fedorova, Jorge Íñiguez-González, Hugo Aramberri
Disordered Systems and Neural Networks · Cross-listed from math.ST
Spectral Thresholds in Correlated Spiked Models and Fundamental Limits of Partial Least Squares
Pierre Mergny and Lenka Zdeborová
We provide a rigorous random
matrix theory analysis of spiked cross-covariance models where the signals across two high-dimensional data channels are partially aligned. These models are motivated by multi-modal learning and form the standard generative setting underlying Partial Least Squares (PLS), a widely used yet theoretically underdeveloped method. We show that the leading singular values of the sample cross-covariance
matrix undergo a Baik-Ben Arous-Peche (BBP)-type phase transition, and we characterize the precise thresholds for the emergence of informative components. Our results yield the first sharp asymptotic description of the signal recovery capabilities of PLS in this setting, revealing a fundamental performance gap between PLS and the Bayes-optimal
estimator. In particular, we identify the SNR and correlation regimes where PLS fails to recover any signal, despite detectability being possible in principle. These findings clarify the theoretical limits of PLS and provide guidance for the design of reliable multi-modal inference methods in high dimensions.
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Soft Condensed Matter
Discrete Differential Geometry for Simulating Nonlinear Behaviors of Flexible Systems: A Survey
Dezhong Tong, Andrew Choi, Jiaqi Wang et al. (+7 more)
Flexible slender structures such as rods, ribbons, plates, and shells exhibit extreme nonlinear responses bending, twisting, buckling, wrinkling, and self contact, that defy conventional simulation frameworks. Discrete Differential Geometry (DDG) has emerged as a geometry first, structure preserving paradigm for modeling such behaviors. Unlike finite element or mass spring methods, DDG discretizes geometry rather than governing equations, allowing
curvature, twist, and strain to be defined directly on meshes. This approach yields robust large deformation dynamics, accurate handling of contact, and differentiability essential for inverse design and learning based control. This review consolidates the rapidly expanding landscape of DDG models across 1D and 2D systems, including discrete elastic rods, ribbons, plates, and shells, as well as multiphysics extensions to contact,
magnetic actuation, and fluid structure interaction. We synthesize applications spanning mechanics of nonlinear instabilities, biological morphogenesis, functional structures and devices, and robotics from manipulation to soft machines. Compared with established approaches, DDG offers a unique balance of
geometric fidelity, computational efficiency, and algorithmic differentiability, bridging continuum rigor with real time, contact rich performance. We conclude by outlining opportunities for multiphysics coupling, hybrid physics data pipelines, and scalable GPU accelerated solvers, and by emphasizing DDG role in enabling digital twins, sim to real transfer, and intelligent design of next generation flexible systems.
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All authors Dezhong Tong, Andrew Choi, Jiaqi Wang, Weicheng Huang, Zexiong Chen, Jiahao Li, Xiaonan Huang, Mingchao Liu, Huajian Gao, K. Jimmy Hsia
Mesoscale and Nanoscale Physics
Néel-Vector-Orientation Induced Direction-Robust Spin Filtering in Two-Dimensional Altermagnets
Xin Chen, Jin Zou, Lipeng Song et al. (+6 more)
Whether an antiferromagnet can host direction-robust
spin-polarized transport without a conventional
spin-selective band gap remains a central challenge in
antiferromagnetic spintronics. Here we establish a gapless, direction-robust
spin-filtering mechanism in a compensated two-dimensional altermagnetic Weyl semimetal that requires neither a
spin-selective band gap nor a large velocity contrast between
spin projections. Using Janus monolayer Ta$_2$TeSeO as a realistic platform, we combine
symmetry analysis with first-principles calculations, full-Brillouin-zone Wannier interpolation, and semiclassical transport. Rotating the Néel vector removes a
unitary-mirror constraint and shifts one Weyl-cone pair away from its parent high-
symmetry line. For an in-plane Néel vector, the residual $C_{2z}\mathcal T$
symmetry forbids the independent $\sigma_y$ mass that would open a local gap, allowing the reconstructed cones to shift in momentum while remaining gapless. Breaking
unitary $C_{2z}$ simultaneously lifts the energy equivalence of the remaining mirror-pinned Weyl cones. The resulting coexistence of a metallic
spin-projected
manifold and a low-DOS Weyl-derived
manifold produces a predominantly DOS-driven conductance imbalance. At charge neutrality and 20~K, the longitudinal conductivity polarization for $\mathbf n\parallel x$ remains positive for every in-plane current direction and ranges from $76.4\%$ to $82.0\%$. The degenerate in-plane
magnetic anisotropy facilitates reversible switching between
symmetry-related
spin-filtering states using strain or weak anisotropic fields. This Néel-vector-driven
symmetry mechanism provides a general route to direction-robust gapless
spin filtering in compensated altermagnets.
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All authors Xin Chen, Jin Zou, Lipeng Song, Wei Sun, Yiwen Wu, Luyao Zhu, Xu Cheng, Duo Wang, Biplab Sanyal
Materials Science
Hybridization in van der Waals epitaxy of PtSe2/h-BN and PtSe2/graphene heterostructures
Meryem Bouaziz, Samir El Masaoudi, Aymen Mahmoudi et al. (+10 more)
Van der Waals (vdW)
heterostructures, which combine bi-dimensional materials of different properties, enable a range of
quantum phenomena. Here, we present a comparative study between the electronic properties of mono- and bi-layer of platinum diselenide (PtSe2) grown on hexagonal boron nitride (h-BN) and
graphene substrates using molecular beam epitaxy (MBE). Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), the electronic structure of PtSe2/
graphene and PtSe2/h-BN vdW
heterostructures are investigated in systematic manner. In contrast to PtSe2/h-BN, the electronic structure of PtSe2/
graphene reveals the presence of interlayer hybridization between PtSe2 and the
graphene, which is evidenced by minigap openings in the {\pi}-band of
graphene. Furthermore, our measurements show that the valence band maximum (VBM) of monolayer PtSe2 is located at the {\Gamma} point with different binding energies of about -0.9 eV and -0.55 eV relative to the
Fermi level on h-BN and
graphene and substrates, respectively. Our results represent a significant advance in the understanding of electronic hybridization between TMDs and different substrates, and they reaffirm the crucial role of the substrate in any nanoelectronic applications based on van der Waals
heterostructures.
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All authors Meryem Bouaziz, Samir El Masaoudi, Aymen Mahmoudi, Eva Desgue, Marco Pala, Pavel Dudin, Mathieu G. Silly, Julien Chaste, Fabrice Oehler, Pierre Legagneux, Jose Avila, Iann C. Gerber, Abdelkarim Ouerghi
Soft Condensed Matter
Ion transport through differently charged nanoporous membranes: from a single nanopore to multi-nanopores
Hongwen Zhang, Bowen Ai, Zekun Gong et al. (+3 more)
Nanoporous membranes, leveraging their high-throughput characteristics, have been widely applied in fields such as molecular separation and energy conversion. Due to interpore interactions, besides the applied voltage and solution environment, the ion transport properties in porous membranes are influenced by the pore number and spacing. Here, to understand and control the transport properties of nanopore arrays, we systematically investigate the ion transport characteristics through membranes with different charge properties, pore numbers, and interpore distances. Using numerical simulations, we analyzed local ionic concentrations and electric potential in nanopore arrays containing nanopores with uniformly charged walls as well as unipolar diodes i.e., pores containing a junction between a charged zone and a neutral zone, and showed significant ion concentration polarization (ICP) for all studied cases. As the number of pores increased and the interpore spacing decreased, the enhanced interpore interactions through ICP led to a greater deviation of the total ionic current from the linear superposition of single-pore currents. Conversely, in bipolar nanopores whose walls contain a junction between positively and negatively charged zones ICP becomes negligible, and interpore interactions are substantially reduced. Furthermore, for membranes with various charge properties, the total current through nanopore arrays presents different quantitative dependence on the pore number under varying pore spacings. Our findings clarify the mechanism of interpore interactions in modulating ion transport through porous membranes, providing critical insights for designing nanofluidic devices based on nanopore arrays, such as nanopore-array sensors.
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All authors Hongwen Zhang, Bowen Ai, Zekun Gong, Tianyi Sui, Zuzanna S. Siwy, Yinghua Qiu
Superconductivity
Enhanced Superconducting Diode Effect in the Asymmetric Hatsugai-Kohmoto Model
Kai Chen and Pavan Hosur
The superconducting diode effect (SDE), characterized by a nonreciprocal supercurrent, has attracted significant
attention in recent years due to its potential applications. However, most studies have focused on weakly correlated models, leaving the impact of strong electron-electron interactions on the SDE largely unexplored. In this work, we bridge this gap by investigating the SDE in asymmetric band metals with Hatsugai-Kohmoto (HK) interaction, which are exactly solvable due to their locality in Bloch momentum space. Through a combination of low-energy analysis and a numerical self-consistent approach, we demonstrate that HK interaction can enhance the SDE's quality factor. Our findings shed light on the role of strong electron-electron correlations in shaping the SDE.
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Soft Condensed Matter
Memory as activity: pattern formation in a conserved scalar field
Vaishnavi Gajendragad and Suropriya Saha
We explore the concept of
memory in scalar active matter, focusing on the collective dynamics of particles whose interactions depend on their evolutionary history rather than solely on their current configuration. We introduce the idea of an active particle whose velocity includes an active contribution that depends on its past trajectory suitably weighted by a
memory kernel. The
memory kernel is unrelated to the thermal noise acting on the particle, meaning that the dynamics breaks detailed balance at the microscopic level. We show that the number density of these active particles is described by a Cahn-Hilliard equation, which typically describes passive phase separation, suitably modified to account for this particular non-
equilibrium effect. We establish the novel emergent features of the model and use the example of time delayed interactions to highlight its novel pattern-forming abilities through theory and simulations.
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Materials Science
Electrical properties of PbS films doped with iodine by chemical bath deposition
T.B. Charikova, A.Yu. Pavlova, M.R. Popov et al. (+2 more)
We present the results of measurements of bulk current-voltage (I-V) characteristics and local surface I-V characteristics by atomic force microscopy (AFM) of iodine-doped PbS films. It is established that bulk I-V curves of both undoped and iodine-doped PbS films demonstrate a linear (ohmic) U(I) dependence. The tipe of local surface I-V characteristics is ohmic at the concentration range of the dopant 0<[NH4I]<=0.10 M and becomes rectifying at [NH4I]>=0.15 M, which is determined by a decrease in the size and a change in the shape of the film grains, as well as a decrease in the surface roughness of the film. An increase in the iodine content in the PbS(I) films leads to nonlinear dependences of the microscopic characteristics and photoelectric parameters of the PbS(I) films. A sharp decrease in the
diffusion coefficient, the beginning of an increase in the charge carrier lifetime, a maximum in voltage sensitivity and specific detectability are observed in the PbS(I) film chemically deposited from a reaction mixture containing [NH4I] = 0.15 M. This indicates that the optimalconcentration of iodine in the film is 2.7 at.%.
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All authors T.B. Charikova, A.Yu. Pavlova, M.R. Popov, A.V. Pozdin, L.N. Maskaeva
Materials Science · Cross-listed from physics.comp-ph
Large-scale stochastic propagation method beyond the sequential approach
Zhichang Fu, Yunhai Li, Weiqing Zhou et al. (+1 more)
The $O(N)$
stochastic propagation method, which relies on the numerical solution of the time-dependent Schrödinger equation using random initial states, is widely used in large-scale first-principles calculations. In this work, we eliminate the conventional sequential computation of intermediate states by introducing a concurrent strategy that minimizes information redundancy. The new method, in its state-, moment-, and energy-based implementations, not only surpasses the time step constraint of sequential propagation but also maintains precision within the framework of the Nyquist-Shannon sampling
theorem. Systematic benchmarking on one billion atoms within the tight-binding model demonstrates that our new concurrent method achieves up to an order-of-magnitude speedup, enabling the rapid computation of a wide range of electronic, optical, and transport properties. This performance breakthrough offers valuable insights for enhancing other time-propagation
algorithms, including those employed in large-scale
stochastic density functional theory.
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All authors Zhichang Fu, Yunhai Li, Weiqing Zhou, Shengjun Yuan
Statistical Mechanics
Breakdown of hydrodynamics in a one-dimensional cold gas
Taras Holovatch, Yuri Kozitsky, Krzysztof Pilorz et al. (+1 more)
The following model is studied analytically and numerically: point particles with masses $m,\mu,m, \dots$ ($m\geq\mu$) are distributed over the positive half-axis. Their dynamics is initiated by giving a positive velocity to the particle located at the origin; in its course the particles undergo elastic collisions. We show that, for certain values of $m/\mu$, starting from the initial state where the particles are equidistant the system evolves in a hydrodynamic way: (i) the rightmost particle (blast front) moves as $t^{\delta}$ with $\delta < 1$; (ii) recoiled particles behind the front enter the negative half-axis; (iii) the splatter – the particles with locations $x\leq 0$ – moves in the ballistic way and eventually takes over the whole energy of the system. These results agree with those obtained in S. Chakraborti et al, SciPost Phys. 2022, 13, 074, for $m/\mu=2$ and random initial particle positions. At the same time, we explicitly found the collection of positive numbers $\{\mathcal{M}_i, i \in \mathbf{N} \}$ such that, for $m/\mu = \mathcal{M}_i$, $i\leq 700$, the following holds: (a) the splatter is absent; (b) the number of simultaneously moving particles is at most three; (c) the blast front moves in the ballistic way. However, if, similarly as in S. Chakraborti et al, the particle positions are sampled from a uniformly distributed ensemble, for $m/\mu = \mathcal{M}_i$ the system evolves in a hydrodynamic way.
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All authors Taras Holovatch, Yuri Kozitsky, Krzysztof Pilorz, Yurij Holovatch
Mesoscale and Nanoscale Physics
Attaining the Ground State of Kagome Artificial Spin Ice via Ultrafast Site-Specific Laser Annealing
D. Pecchio, S. Sahoo, V. Scagnoli et al. (+1 more)
Artificial
spin ices (ASIs) provide a versatile platform to explore
magnetic frustration and emergent phenomena. However, in kagome ASI, experimental access to the ground state remains elusive due to dynamical freezing. Here, we demonstrate a deterministic and rewritable approach to attain the ground state using ultrafast, site-selective
laser annealing. By engineering sublattice-dependent optical absorption through selective capping of the nanomagnets with Cr or utilizing different nanomagnet thicknesses, we achieve selective partial demagnetization of one sublattice under a sub-coercive
magnetic field, driving the system into the ground state in a single switching step.
Magnetic force microscopy reveals nearly perfect long-range ordering, while heat-transfer simulations confirm the sublattice-selective excitation mechanism. This work establishes an ultrafast method to attain the kagome ASI ground state, which does not require a modification of the geometry of the ASI or the materials used for the individual nanomagnets. Beyond ground-state writing, this site-selective activation provides an important tool for controlling the
magnetic states, which is important for applications such as reconfigurable magnonic
crystals, neuromorphic computing and programmable nanomagnetic logic.
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All authors D. Pecchio, S. Sahoo, V. Scagnoli, L. J. Heyderman