Materials Science
From Deposition Stress to Surface Reactivity: Strain-Dependent Hydrogen Evolution on Sputtered Platinum Thin Films
Sabrina Baha, Alejandro E. Perez Mendoza, Leonardo H. Morais et al. (+9 more)
Strain has emerged as a promising approach for tuning electrocatalytic properties, yet its role in sputter-deposited thin films remains poorly understood. In this work, magnetron-sputtered platinum (Pt) thin films with different stress states were prepared by varying the sputter pressure. The resulting changes in microstructure, residual strain, and hydrogen
evolution reaction (HER) activity were investigated using complementary characterization techniques and density functional theory (DFT) calculations. Structural analysis reveals a transition of (111)-textured Pt thin films from dense and smooth films at low pressures, to more porous microstructures with increased roughness at higher pressures. Electrochemical measurements show that films deposited at low sputter pressure exhibit the highest HER activity, while higher sputter pressures lead to reduced activity despite increased surface area. DFT calculations demonstrate that
lattice strain alters hydrogen adsorption energetics and surface coverage on Pt(111), providing a mechanistic explanation for the observed activity trends. Overall, the results highlight that HER activity in sputtered Pt thin films is governed by the interplay of residual strain, microstructure, and hydrogen coverage.
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All authors Sabrina Baha, Alejandro E. Perez Mendoza, Leonardo H. Morais, Aleksander Kostka, Shivam Shukla, Ellen Suhr, Andre Oliveira, Annika Gatzki, Henrik H. Kristoffersen, Jan Rossmeisl, Corina Andronescu, Alfred Ludwig
Strongly Correlated Electrons
Quantum Electron Quasicrystal
Pierre-Antoine Graham, Filippo Gaggioli and Liang Fu
The strongly correlated phases of the homogeneous electron gas constitute the vocabulary of many-body condensed matter physics and find a natural realization in
semiconductors. In this setting, recent neural-network variational Monte Carlo calculations discovered an unexpected
quantum phase of matter in wide
quantum wells: an electronic quasicrystal formed by a
bilayer Wigner
crystals with a 30-degrees twist. This state defies classical expectations and emerges in a regime dominated by
quantum fluctuations. Here, we develop an analytical framework to reveal its origin. By computing zero-point energy corrections to
bilayer Wigner
crystal configurations, we show that
quantum fluctuations qualitatively reshape the energetic landscape, destabilizing the classical honeycomb state and selecting the 30-degrees quasicrystalline ground state over a broad parameter range. Our results identify zero-point motion as the mechanism stabilizing the electronic quasicrystal and establish a route to spontaneous moiré physics driven by many-body
quantum effects.
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Statistical Mechanics · Cross-listed from q-bio.PE
Higher-order interactions in ecology can be hidden in plain sight
Violeta Calleja-Solanas, Santiago Lamata-Otín, Carlos Gómez-Ambrosi et al. (+2 more)
Higher-order interactions are increasingly recognized as a key component of ecological dynamics. However, we show that higher-order Lotka-Volterra dynamics can, in some scenarios, be accurately reproduced by effective pairwise models fitted to the same abundance time series. Consequently, higher-order interactions cannot, in general, be inferred from time-series data alone. We further identify a fundamental problem of mechanistic identifiability, whereby distinct interaction mechanisms generate nearly indistinguishable dynamics, potentially leading to accurate yet misleading ecological interpretations. Our results highlight the need to complement time-series data with additional ecological information to infer interaction structure reliably.
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All authors Violeta Calleja-Solanas, Santiago Lamata-Otín, Carlos Gómez-Ambrosi, Jesús Gómez-Gardeñes, Sandro Meloni
Mesoscale and Nanoscale Physics
Anomalous Transverse Thomson Effect
Ying-Fei Zhang, Zhi-Fan Zhang, Zhen-Gang Zhu et al. (+1 more)
We formulate the anomalous transverse Thomson effect (ATTE), the long-missing Thomson counterpart of the anomalous
Hall and anomalous Nernst effects. Its coefficient is not unique but depends on the electrical boundary condition: $\tau_{\rm ATTE}^{(j)}$, defined for a spatially uniform imposed current density, and $\tau_{\rm ATTE}^{(E)}$, defined for equipotential electrodes. Both are fully determined by the total anomalous Nernst coefficient (ANC) and its temperature dependence, while $\tau_{\rm ATTE}^{(E)}$ acquires an additional contribution from the temperature dependence of the longitudinal resistivity. This relation is model independent within local linear response and applies to the total ANC regardless of whether its microscopic origin is intrinsic or extrinsic. Using a massive Dirac model for Fe$_3$Sn$_2$, we show that Berry
curvature near the gapped Dirac cones enhances the ANC-related contributions to $\tau_{\rm ATTE}^{(E)}$. In the low-temperature limit, both $\tau_{\rm ATTE}^{(j)}/S_{xy}^{\rm A}$ and $\tau_{\rm ATTE}^{(E)}/S_{xy}^{\rm A}$ approach a value of three. We further extract $\tau_{\rm ATTE}^{(E)}$ from reported experimental data for CoS\(_2\), Co\(_3\)Sn\(_2\)S\(_2\) and CeCrGe\(_3\); for CeCrGe$_3$ it reaches approximately -20 $\mu V/K$, and we estimate the maximum achievable cold-side heat current density to assess its cooling potential. Because the ATTE can be evaluated directly from existing ANC and longitudinal resistivity data, it is readily testable without additional equipment or measurements.
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All authors Ying-Fei Zhang, Zhi-Fan Zhang, Zhen-Gang Zhu, Gang Su
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Macroscopic entanglement between two magnon modes via two-tone driving of a superconducting qubit
Rong-Can Yang, Gang Liu, Gen Li et al. (+1 more)
The cavity-mediated coupling between
magnons in an yttrium-iron-garnet (YIG) sphere and a superconducting
qubit has recently been demonstrated as a new platform for preparing macroscopic
quantum states. Here, based on this system, we propose to entangle two
magnon modes in two YIG spheres by driving the
qubit with a two-tone field and by appropriately choosing the frequencies and strengths of the two driving fields. We show that strong
entanglement can be achieved with fully feasible parameters. We further provide a detection scheme for experimentally verifying the
entanglement. Our results indicate that macroscopic
entanglement between two
magnon modes in two millimeter-sized YIG spheres, involving more than $10^{18}$
spins, can be realized using currently available parameters, which finds promising applications in fundamental studies, such as macroscopic
quantum mechanics and the test of unconventional decoherence theories.
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All authors Rong-Can Yang, Gang Liu, Gen Li, Jie Li
Soft Condensed Matter
Solvent-induced memory effects in a model electrolyte
Sleeba Varghese, Benjamin Rotenberg and Pierre Illien
The fluctuations of ions in polar solvents remain poorly understood theoretically due to the complex coupling between ionic motion and solvent polarization. Indeed, while all-atom resolution can be achieved in numerical simulations, analytical approaches require suitable levels of coarse-graining. In this work, we describe ions and solvent molecules as interacting Brownian particles and use
stochastic density functional theory to derive a generalized Langevin equation for the ionic charge density, explicitly accounting for solvent-mediated
memory effects. In the regime where there is a clear timescale separation between fast solvent and slow ion dynamics, we obtain simple expressions for dynamical charge structure factors, which are validated by BD simulations. For slow solvents, we predict an emerging two-step relaxation in ionic dynamics. These results provide a mesoscopic approach for ion-solvent dynamics and open pathways to study fluctuation-induced phenomena in electrolytes.
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Materials Science
Winding feature and thermal evolution of the Dirac magnons in CrI$_3$
Weiliang Yao, Matthew B. Stone, Colin L. Sarkis et al. (+4 more)
Two-dimensional honeycomb
lattice ferromagnet chromium tri-iodide (CrI$_3$) has attracted tremendous interest because it retains ferromagnetism down to the monolayer limit and hosts intriguing topological
magnons. As a prototypical van der Waals magnet, CrI$_3$ provides an ideal platform for exploring the interplay between reduced dimensionality,
magnetic order, and nontrivial
spin excitations. Here, using inelastic
neutron scattering together with improved sample quality, we uncover the
magnon winding feature around the $K$-point of the hexagonal Brillouin zone, a key signature of Dirac
magnons. In addition, we find that the
magnon energy follows a $T^2$-renormalization behavior at elevated temperatures, consistent with
magnon-
magnon interactions. These results provide previously missing information on the
magnon spectrum of CrI$_3$ and further consolidate the topological nature of its
spin excitations.
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All authors Weiliang Yao, Matthew B. Stone, Colin L. Sarkis, Yi Li, Ruixian Liu, Xingye Lu, Pengcheng Dai
Materials Science · Cross-listed from physics.optics
Elastic and structural anisotropy in silica thin films for gravitational-wave detectors
Brenda Bracco, Michele Magnozzi, Stefano Colace et al. (+11 more)
The thermal noise of mirror coatings for gravitational-wave detectors critically depends on the elastic properties of the constituent materials. Data analyses and theoretical models typically assume each material is homogeneous and isotropic, but isotropy has never been explicitly verified. Using Brillouin light scattering (BLS), we demonstrate for the first time that ion-beam-sputtered SiO2 – a material still viable for future mirror coatings – exhibits cylindrical elastic
symmetry, with in-plane isotropy but a notable 6% compressive anisotropy along the film normal. This anisotropy remains unchanged after the post-deposition heat treatment currently used in ground-based detectors (500 $^\circ$C, 10 h) but is nearly eliminated at 900 $^\circ$C. Infrared reflectivity experiments support these findings by directly revealing heterogeneities in the distribution of bridging and non-bridging oxygen structures along the growth axis. While BLS measures the real part of the elastic constants at GHz frequencies, the data reveal negligible contributions from mechanical relaxations in the kHz-GHz range, making BLS a valid substitute for low-frequency properties obtained from standard anisotropy-insensitive techniques. Our results highlight that restoring isotropy through heat treatment – by softening the material, enabling more than 7% out-of-plane expansion, and smoothing out structural heterogeneities – may play a key role in reducing thermal noise. This proof-of-concept study extends beyond silica, providing critical insights for the design of future coatings.
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All authors Brenda Bracco, Michele Magnozzi, Stefano Colace, Maurizio Canepa, Giulio Favaro, Marco Bazzan, Massimo Granata, David Hofman, Alessandro Di Michele, Laura Silenzi, Gianpietro Cagnoli, Giovanni Carlotti, Paola Sassi, Silvia Corezzi
Statistical Mechanics
Large Deviation Functions of Open Quantum Systems with Strong Symmetries
Jiayi Gu, Hailong Wang, Shanhe Su et al. (+1 more)
In open
quantum systems with strong
symmetries, the global rate function is typically non-convex and thus cannot be directly computed from the global scaled cumulant generating function (SCGF) via the Gartner-Ellis
theorem. To overcome this limitation, we develop a framework that applies the
theorem locally within each
symmetry sector: local rate functions are computed for each sector, and the global rate function is subsequently reconstructed as the minimum envelope of these local functions. We illustrate our method using an exactly solvable model and an open Heisenberg chain with XXX interactions. For the latter system with continuous non-Abelian
symmetries, our approach reveals sector-dependent fluctuations ranging from Poissonian to super-Poissonian statistics, together with emergent intermittency, demonstrating the broad applicability of our framework.
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All authors Jiayi Gu, Hailong Wang, Shanhe Su, Fei Liu
Materials Science
Disentangling magnetic and optical contributions in ultrafast dynamics of antiperovskite non-collinear antiferromagnets
J. Kimak, Tomas Ostatnicky, M. Nerodilova et al. (+14 more)
Non-collinear antiferromagnets are a class of
spin-polarized antiferromagnets in which
chiral spin textures give rise to Berry-
curvature-driven phenomena, such as the anomalous
Hall effect (AHE), without net magnetization. We investigate the properties of thin films of antiperovskite non-collinear
antiferromagnetic metals Mn3NiN and Mn3GaN using pump-probe experiments. In both materials, we observe a strong dependence of pump-polarization-independent dynamics, induced by femtosecond
laser pulses, on the angle between the sample normal and the direction of probe propagation. In Mn3NiN, where the presence of a sizable AHE indicates the {\Gamma}4g phase, the measured magnetooptical (MO) signals acquire an additional, strong dependence on the external
magnetic field when the probe pulses are incident at nonzero angles. In contrast, in Mn3GaN, where the absence of AHE indicates the {\Gamma}5g phase, the measured signals do not depend on the
magnetic field. Using probe-polarization-resolved measurements combined with full optical modeling based on Yeh's formalism, we quantitatively separate
magnetic and non-
magnetic contributions to the measured signals. We show that in Mn3NiN, the observed
magnetic field dependence results from field-controlled redistribution of
magnetic domain populations, enabled by their piezomagnetic moments and detected by a Kerr-like MO effect, while this effect is absent in Mn3GaN. Temperature-dependent measurements reveal a change from single-step to two-step quenching dynamics with increasing temperature in Mn3NiN. This behavior contrasts with the nearly temperature-independent quenching dynamics reported for the non-collinear
antiferromagnetic Heusler compound Mn3Sn, but resembles the crossover from type-I to type-II demagnetization dynamics in metallic ferromagnets.
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All authors J. Kimak, Tomas Ostatnicky, M. Nerodilova, F. Johnson, O. Faiman, T. Trejtnar, D. Boldrin, F. Rendell-Bhatti, J. Zemen, B. Zou, A.P. Mihai, X.Sun, F. Yu, E. Schmoranzerova, L. Nadvornik, L.F. Cohen, P. Nemec
Disordered Systems and Neural Networks · Cross-listed from physics.soc-ph
Two-mode geometry controls multiscale organization in bipartite systems
Ottavia Falconi, Giulio Cimini and Pablo Villegas
Many complex systems are organized around complementary roles and naturally described as bipartite networks. Unveiling their multiscale structure presents a fundamental challenge because coarse-graining procedures must preserve role separation, whereas standard approaches collapse it via one-mode projections. Here we introduce a
Laplacian-based renormalization framework that operates directly on the bipartite architecture, enabling scale transformations while retaining role differentiation. Using controlled bipartite ensembles at criticality, we show that structural imbalance systematically reshapes organization across scales while leaving scaling properties invariant, revealing a separation between universality and geometry. Applying the coarse-graining framework to empirical bipartite networks, we uncover nontrivial multiscale hierarchies for both roles. In contrast, renormalization performed after one-mode projection – which truncates
diffusion paths to nearest neighbors – yields qualitatively different structures. Our results identify two-mode geometry as a fundamental constraint for revealing multiscale organization in systems with role separation.
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Materials Science
Charge-Transfer Induced Reactivity in sp Carbon Atomic Wires: Towards 0-D sp-sp2 Nanostructures
Marco Agozzino, Eleonora Moroni, Yifan Zhang et al. (+2 more)
Carbon Atomic Wires (CAWs) are finite linear chains of sp-hybridized carbon atoms. Here the electrochemical reduction of CAWs in the form of polyynes (i.e. with alternated single-triple bonds) is reported. Upon applying a reducing potential to a solution containing polydispersed hydrogen-capped polyynes, the formation of a black precipitate was observed. Electronic absorption spectroscopy confirmed the irreversible reaction of the carbon chains while excluding degradation or side reactions. Subsequent analyses revealed that the precipitate consisted of amorphous carbon nanoparticles with tunable diameters. This control over particle size is attributed to the modulation of growth kinetics through restricted mass transport toward the solid-
liquid interface. Raman spectroscopy showed that the resulting material exhibits an amorphous sp-sp2 character, with a retained sp fraction exceeding 60%. Smaller nanoparticles displayed reduced disorder within the sp2 domains and a broader distribution of sp-chain lengths preserved in the amorphous
matrix. Additional experiments on size-selected polyynes suggest that this synthesis method allows to better preserve the starting chain length in the final structure. Unlike previously reported amorphous sp-sp2 carbon networks, the nanoparticles produced in this study show remarkable stability under ambient conditions, retaining their sp character for times in excess of six months. These findings pave the way for future applications, particularly as further diameter tuning may enable access to the
quantum-dot regime.
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All authors Marco Agozzino, Eleonora Moroni, Yifan Zhang, Valeria Russo, Carlo Spartaco Casari
Quantum Gases
Quantum phase diagrams for bosons in hexagonal optical potentials: A continuous-space quantum Monte Carlo study
Danilo Nascimento Guimaraes and Laurent Sanchez-Palencia
Hexagonal optical
lattices, emulating
graphene and hexagonal boron nitride (h-BN) structures, provide a versatile platform for exploring strongly correlated
quantum matter. Using continuous-space exact diagonalization and
quantum Monte Carlo simulations, we investigate the phase diagrams of ultracold
bosons in honeycomb and h-BN
lattices. For the honeycomb
lattice, we find significant deviations from the standard Bose–Hubbard model even for strong
lattice amplitudes. We observe suppressed Mott
insulator lobes and the absence of higher-order insulating phases, which we attribute to strong density-assisted tunneling effects. In the h-BN case, a rich phase diagram emerges, featuring multiple Mott lobes with various sublattice occupations, driven by the interplay of
lattice asymmetry, interactions, and particle filling. Our results highlight the necessity of continuous-space treatments for capturing the full complexity of bosonic
quantum phases in hexagonal geometries, paving the way for experimental realizations with ultracold atoms and further theoretical work.
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Superconductivity
Josephson spectroscopy study of kagome superconductors toward the deep point-contact regime
Hailang Qin, Xiao-Yu Yan, Hanbin Deng et al. (+4 more)
Josephson scanning tunneling microscopy (JSTM) has emerged as an important technique for probing the superconducting order parameter at the atomic scale. However, the Josephson current in JSTM may behave quite differently when the coupling strength varies. Here, we push the junction to the deep point-contact regime, reaching a normal-state junction resistance of only 0.15 $h/2e^2 \simeq 2~{\rm k}\Omega$. We demonstrate, using kagome
superconductors, that the zero-bias conductance, a key characteristic of the Josephson current, deviates strongly from the quadratic dependence on the normal-state conductance upon entering the deep point-contact regime. Furthermore, we observe a striking saturation of the zero-bias conductance, which we show arises from the series resistance in the
circuit. This also serves as a cautious reminder when interpreting zero-bias conductance saturation or quantization in studies of exotic physics such as that of Majorana zero modes if the tip-sample junction resistance is extremely small. Finally, we identify an optimum regime where JSTM can be used as an atomic-scale probe for studying pair-density wave states in materials with low superconducting transition temperature, such as AV3Sb5 kagome
superconductors.
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All authors Hailang Qin, Xiao-Yu Yan, Hanbin Deng, Mu-Wei Gao, Guowei Liu, Yuanyuan Zhao, Jia-Xin Yin
Mesoscale and Nanoscale Physics
Sub-kelvin thermal conductivity of substrates and on-chip routing in quantum integrated systems
Charles Bon-Mardion, Arnaud Lorin, Edouard Deschaseaux et al. (+6 more)
The development of large-scale
quantum systems increasingly relies on the close integration of heterogeneous components such as
qubits, control electronics, and readout
circuits, making thermal management at cryogenic temperatures a central challenge in such architectures. In this work, we present an experimental thermal study of two building blocks of such systems: the substrate and the on-chip routing. We first investigate the sub-kelvin thermal conductivity of four substrate materials: high-resistivity silicon, low-resistivity silicon, borosilicate, and sapphire. We report that high-resistivity silicon exhibits the highest thermal conductivity among the substrates studied ($5\cdot10^{-2}$~W/m$\cdot$K at 300~mK), while low-resistivity silicon, borosilicate, and sapphire show lower values ($8\cdot10^{-4}$~W/m$\cdot$K, 2$\cdot10^{-3}$~W/m$\cdot$K, and 2$\cdot10^{-3}$~W/m$\cdot$K at 300~mK, respectively). Ballistic conductance evaluation using a finite-element non-
equilibrium Green's function approach further allows us to extract the
phonon mean free path in each substrate and gives insights into the involved scattering mechanisms. Additionally, we employ a dedicated test vehicle to evaluate the impact of on-chip routing on the thermal conductance of the system. Our measurements with superconducting Nb routing lines reveal that the routing increases the in-plane thermal conductance of the system, but the substrate remains the dominant heat path. These results highlight the critical role of the substrate choice within
quantum systems and underscore the importance of function partitioning through 3D integration approaches for more efficient thermal management in
quantum architectures.
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All authors Charles Bon-Mardion, Arnaud Lorin, Edouard Deschaseaux, Céline Feautrier, Daniel Mermin, Jean Charbonnier, Jing Li, Jean-Luc Sauvageot, Candice Thomas
Materials Science
Transformation-mediated twinning governs plasticity in body-centered cubic nanocrystals under extreme loading
Jan Očenášek, Jesper Byggmästar, Guanying Wei et al. (+2 more)
Plasticity in body-centered cubic (BCC) nanocrystals is often associated with twin nucleation phenomena under extreme loading conditions. Here, we reveal unconventional twinning pathways that operate at the intersection of
crystal plasticity and structural phase transitions. We show that the classical shear-driven twinning mode becomes progressively suppressed with increasing pressure, giving rise to transformation-mediated twinning pathways involving transient HCP or FCC phases. In BCC Fe, Ta, and Nb nanocrystals of moderate elastic stiffness, plasticity is consistently initiated by an elastic instability that triggers a dual-shuffle process mediated by stable or metastable hexagonal closed-packed (HCP) phases. This pathway operates independently of the characteristic {112} twin boundary planes and is driven by compression, challenging the conceptual paradigm for metal plasticity in which plastic deformation arises from shear stresses resolved on specific planes. By contrast, in the archetypal elastically stiffer BCC Mo and W nanocrystals, plastic deformation proceeds via two alternative twinning pathways associated with shear-driven elastic instabilities mediated by highly-distorted face-centered cubic (FCC) phases. Comprehensive analyses of the energy landscapes to the competing nanoscale twinning modes provide mechanistic insight into their activation, establishing a unified framework for transformation-mediated twinning in BCC nanocrystals across a broad range of loading conditions.
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All authors Jan Očenášek, Jesper Byggmästar, Guanying Wei, F. Javier Dominguez-Gutierrez, Jorge Alcalá
Strongly Correlated Electrons
Dominant Role of Sulphur divacancy in Charge Trapping Dynamics in MoS$_2$
Srest Somay, Sitangshu Bhattacharya and Krishna Balasubramanian
Intrinsic defects govern carrier trapping and recombination in two-dimensional
semiconductors, yet the microscopic origin of defect-dependent capture dynamics remains unclear. Here, we compute carrier capture coefficients of vacancy defects, treating monolayer MoS$_2$ as a prototype, from first principles. We find that the single Sulphur vacancy forms a shallow defect with a small capture coefficient of $\sim 10^{-16}\ \mathrm{cm}^3/\mathrm{s}$, whereas the Sulphur divacancy exhibits a capture coefficient larger by seven orders of magnitude, $\sim 10^{-9}\ \mathrm{cm}^3/\mathrm{s}$, despite being only moderately deeper in energy. This enhancement originates from strong
lattice relaxation enabling efficient multiphonon capture. Consequently, single vacancies contribute weakly to trapping, while Sulphur divacancies dominate nonradiative recombination and reduce
quantum yield. In contrast, molybdenum vacancies and Sulphur antisites, although deep, show much smaller capture coefficients, indicating a limited role in carrier trapping in n-type devices.
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Disordered Systems and Neural Networks
Floquet-induced suppression of thermalization in a quasiperiodic Ising chain
Biswajit Paul, Nilanjan Roy and Tapan Mishra
Many-body localized (MBL) systems are known to thermalize in periodically driven systems. In this work, we demonstrate that under proper driving protocol, this thermalization this thermalization can be resisted such that the MBL phase turns into a non-ergodic extended phase, known as the many-body critical (MBC) phase. Considering a kicked quasiperiodic Ising chain, we show that while at high-frequency driving the ergodic, MBL, and the MBC phases coexist, at moderate driving frequencies the MBL phase is completely suppressed and the MBC phase proliferates in the parameter space. Using quasienergy statistics, Floquet eigenstates, autocorrelation dynamics, and
entanglement growth, we characterize the emergent phases and identify non-monotonic signatures revealing richness of the nonergodic phases. Our results establish Floquet driving as a powerful route to stabilizing nonergodic extended many-body phases beyond the conventional Floquet-MBL paradigm.
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Disordered Systems and Neural Networks
Probing critical phases in quasiperiodic systems via subsystem information capacity
Huaijin Dong and Long Zhang
We systematically investigate the
entanglement and information dynamics of quasiperiodic systems across their extended, critical, and localized phases, aiming to identify dynamical signatures that can reveal the multifractal spatial structure of critical states and distinguish critical phases from the extended and localized regimes. Focusing on the generalized Aubry-André-Harper model, we complement the half-chain
entanglement entropy with the spatially resolved subsystem information capacity (SIC) and demonstrate that critical states exhibit pronounced spatial heterogeneity absent in the extended and localized phases. In the steady state, the SIC reveals a stepwise ramp as a function of subsystem size, reflecting an underlying fragmentation of the chain into weakly connected subregions. Dynamically, information initially localized within such a subregion can undergo coherent long-lived oscillations, dubbed subregion echoes, whose period scales with the subregion length, in quantitative agreement with a quasiparticle picture of confined quasiparticle reflections. We trace this internal fragmentation to the incommensurately distributed zeros (IDZs) in the off-diagonal hopping terms of the
Hamiltonian. To establish the generality of the SIC as a diagnostic tool, we further apply it to a mobility-edge phase with coexisting extended and localized states and to a critical phase that does not originate from IDZ fragmentation, and show that the SIC can cleanly distinguish these scenarios through their distinct steady-state profiles, initial-site sensitivities, and the presence or absence of subregion echoes. Our results demonstrate that the SIC serves as a powerful real-space probe for diagnosing critical phases and uncovering the bottlenecked connectivity that underlies the multifractal structure of critical states.
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Strongly Correlated Electrons
Topological spin freezing in frustrated quantum materials
U. Jena, M. Barman, A. Pradhan et al. (+1 more)
Competing interactions, non-trivial electronic band
topology,
quantum fluctuations, and the interplay between emergent degrees of freedom in frustrated
quantum materials can give rise to a wide range of exotic phenomena. Glassy dynamics, originally studied in amorphous materials and biological systems, has recently attracted considerable interest in
quantum condensed matter, particularly in relation to the collective behavior of
spins, quasiparticle excitations, and topological
spin textures. Here, we investigate the emergence of unconventional glassy
spin dynamics in a broad class of frustrated
quantum materials, where
spin freezing exhibit distinct signatures in both thermodynamic and microscopic measurements. Using a comprehensive set of experimental probes, including thermodynamic, NMR, ($\mu$SR), and
neutron scattering, we identify characteristic signatures of topological
spin-glass behavior and these complementary techniques reveal unconventional
spin dynamics, short-range
spin correlations, emergent low-energy excitations, and glassy behavior of topological origins, distinguishing these states from conventional
spin glasses and disordered magnets. Furthermore, we discuss the role of hydrodynamic
spin modes in governing glassy dynamics and the emergence of
spin-jam states in frustrated
lattices, providing a unified framework for understanding unconventional
spin freezing of topological origin and bridging experimental observations with theoretical models. This review aims to advance our understanding of collective many-body phenomena arising from competing interactions, topological defects, collective excitations,
quantum entanglement, and
symmetry constraints. Such insights may facilitate the discovery and design of novel
quantum materials and help address fundamental questions in contemporary condensed matter physics, with potential implications for future
quantum technologies.
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All authors U. Jena, M. Barman, A. Pradhan, P. Khuntia
Mesoscale and Nanoscale Physics
Quantum oscillations and nonsaturating magnetoresistivity in nodal-line semimetals
Rui Min and Yi-Xiang Wang
Understanding the magnetotransport behaviors in topological systems remains alluring, as a lot of intrinsic information could be extracted, e.g., the band structures, Berry phase,
Fermi surface, carrier density, and so on. Motivated by the recent magnetotransport developments in nodal-line semimetal, EuGa4, in this paper, we will study the magnetotransport properties of the system, focusing on the
quantum oscillations and nonsaturating magnetoresistivity (MR). Firstly, we analyze the chemical potential and magnetoconductivity oscillations with the
magnetic field and reveal that there exist two distinct oscillation frequencies, which are caused by the characteristic
torus Fermi surface and can be regarded as an important experimental signature of nodal-line semimetals. Then we calculate the MR and find that although the MR is nonsaturating with the
magnetic field in the low-energy region, the MR ratio is much smaller than that reported in the experiment.
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Mesoscale and Nanoscale Physics
Dzyaloshinskii-Moriya interaction as a coherence diagnostic for chirality-induced spin selectivity
Vishvendra S. Poonia
Whether chirality-induced
spin selectivity (CISS) reflects coherent SU(2)
spin rotation or incoherent
spin-dependent filtering is a central unresolved question in molecular spintronics, with implications ranging from asymmetric chemistry to
quantum information. We show that these two scenarios are distinguishable by a sharp
symmetry criterion on the superexchange interaction mediated by a
chiral molecular bridge. Coherent CISS, implemented as a
unitary spin rotation of the tunneling electron, generates a
giant Dzyaloshinskii-Moriya (DM) interaction with ratio |D|/JH up to 3, which is two orders of magnitude beyond intrinsic Rashba
spin-orbit coupling in Si/SiGe. Incoherent CISS, represented by any Hermitian (non-
unitary but
spin-diagonal) tunneling
matrix, produces D = 0 identically; we prove this as a structural
theorem, reinforced by a Lindblad argument that dissipative
spin filtering cannot modify virtual-tunneling-mediated superexchange. The DM interaction thus serves as a coherence order parameter, nonzero only when
quantum amplitudes for opposite-
spin transmission maintain a fixed relative phase. We derive closed-form angular, enantiomeric, and sensitivity signatures and show that the critical coherent rotation angle lies two orders of magnitude below current transport-inferred values and is accessible to existing 10 kHz exchange spectroscopy in gate-defined
quantum dots. Five candidate molecules are predicted to exceed this threshold by one to two orders of magnitude even in a conservative interface-amplification scenario. The proposed measurement converts a long-standing transport controversy into a binary
spin-
qubit experiment with
quantum-amplitude resolution.
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Superconductivity
Massive Mitigation of Transport AC Losses in Superconducting Hybrid CORC-TSTC Cables
Hasan N. Al-Ssalih, Antonio Badía-Majós and Harold S. Ruiz
High-current superconducting cables are emerging as key enablers for next-generation power transmission systems; however, their deployment is often limited by transport AC losses. Hybrid superconducting cables combining Conductor-on-Round-Core (CORC) and Twisted Stacked-Tape Conductor (TSTC) architectures have recently been proposed as a promising route toward cables with high current capacity and compact form factors. However, their electrodynamic response under transport current operation remains poorly understood, particularly regarding how current injection conditions govern internal current redistribution. Here, we employ a fully-3D electromagnetic model, previously validated against magnetisation experiments in equivalent cables, to investigate the influence of current injection strategy on the electrodynamics of hybrid CORC-TSTC cables under self-field conditions. By comparing configurations in which the total current is either injected through a common connection between the CORC and TSTC conductors (non-insulated feeding) or supplied independently to each conductor (insulated feeding), we show that electrical coupling in non-insulated designs leads to strong current redistribution, pronounced waveform distortion and elevated AC losses once the CORC layers approach
magnetic saturation. In contrast, independent current feeding suppresses inter-conductor current exchange, stabilises the current waveforms, and exhibits an outstanding reduction in transport AC losses of up to 90% at practical operating currents, compared with conventional feeding schemes. These findings reveal the central role of the current injection strategy in governing the internal electrodynamics and energy dissipation of hybrid superconducting cables, and identify the electrical decoupling of the constituent conductors at the feeding point as a simple and scalable route toward ultra-efficient power cables.
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Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Local droplet etching-assisted quantum dot epitaxy for telecom C-band quantum light emitters
Karolina E. Połczyńska, Paweł Wyborski, Michał Gawełczyk et al. (+4 more)
Significant progress in
quantum light sources for
quantum communication applications requires reproducible and symmetric
quantum emitters acting as single-
photon sources capable of generating entangled
photons on demand at specific telecom wavelengths. Here, we propose telecom-emitting epitaxial
quantum dots (QDs) fabricated using the local droplet etching (LDE) approach. The resulting well-defined, low-density ($10^9$/cm$^2$) QDs based on In$_{x}$Ga$_{1-x}$As are formed in symmetric LDE nanoholes (in-plane aspect ratio of 1.14) in In$_{0.52}$Al$_{0.48}$As. Detailed transmission electron microscopy provides comprehensive insight into the structural integrity, interface quality, and compositional profiles of the QDs, which underpin their promising optical properties. Photoluminescence spectroscopy reveals narrow emission lines (0.2 meV) and high optical quality, while second-order autocorrelation measurements confirm clear single-
photon emission, with $g^{(2)}(0)=0.07\pm0.02$ under above-band continuous-wave excitation and $g^{(2)}(0)=0.16 \pm 0.18$ under pulsed excitation. Precise numerical modeling, combining multiband $\boldsymbol{k} \cdot \boldsymbol{p}$ and configuration-interaction methods, supports the optical characterization and identifies thermal excitation pathways that explain the persistence of emission up to
liquid-nitrogen temperatures. These results highlight the versatility of the LDE approach for integrating new material systems and pave the way toward scalable fabrication of
quantum light sources with tailored emission properties.
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All authors Karolina E. Połczyńska, Paweł Wyborski, Michał Gawełczyk, Shima Kadkhodazadeh, Battulga Munkhbat, Stefano Sanguinetti, Elizaveta Semenova
Statistical Mechanics
Emergent conserved quantities via irreversibility
Alex Blokhuis, Martijn van Kuppeveld, Daan van de Weem et al. (+1 more)
Conserved quantities increasingly underpin the inference of physical models. Recently new conserved quantities have been found in this context, that currently lack an interpretation. Here, we show that irreversible reactions in CRNs and Markov Chains lead to emergent conservation laws and broken cycles. Linearly dependent currents - characterized by the "co-production index" - arise due to irreversible reactions. We derive a law relating conserved quantities, broken cycles, and co-production. This resolves a recent conundrum posed by a machine-discovered candidate for a non-integer conservation law. Our findings introduce heretofore overlooked extensions to a widely used index law for CRNs and Markov Chains that undercounts conservation laws. This furnishes new tools and immediate applications for the inference and analysis of models based on conservation laws.
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All authors Alex Blokhuis, Martijn van Kuppeveld, Daan van de Weem, Robert Pollice
Statistical Mechanics
Lack of self-averaging of the critical internal energy in a weakly-disordered Baxter model
Ramgopal Agrawal, Victor Dotsenko, Maxym Dudka et al. (+3 more)
We investigate the first two moments of the critical internal energy $E$ in a weakly disordered two-dimensional Baxter eight-vertex model as a function of the system size $L$, evaluated at the pseudo-critical point. Disorder is introduced via an equivalent representation of the pure eight-vertex model in terms of two
ferromagnetic Ising models coupled by a four-
spin interaction of strength $g_0$, where the Ising couplings consist of a uniform
ferromagnetic part $J>0$ supplemented by weak Gaussian spatial disorder. In the critical regime, the model is formulated in terms of interacting Grassmann-Majorana spinor fields with quartic interactions and analyzed, for small positive $g_0$, using a combination of replica and renormalization-group methods. We also run extensive numerical simulations measuring the critical internal energy. Our results show that its relative variance increases with $L$ and approaches a finite constant as $L \to \infty$ for both $\pm g_0$. Hence, fluctuations remain relevant independently of the sign of $g_0$ (and thus of the specific-heat exponent), implying a lack of self-averaging of both the critical internal energy and the free energy. Consequently, reliable estimates of these quantities require averaging over many disorder realizations. In addition, we numerically confirm earlier predictions concerning the absence of self-averaging of the critical internal energy in the disordered Ising model.
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All authors Ramgopal Agrawal, Victor Dotsenko, Maxym Dudka, Marco Picco, Enzo Marinari, Gleb Oshanin
Mesoscale and Nanoscale Physics
Intrinsic Floquet Generation and $1/I$ Quantum Oscillations in a Sliding Charge-Density Wave
Yi Zhou
Recent experiments [Phys. Rev. B 109, 245123 (2024)] revealed striking inverse-current (1/I)
quantum oscillations in quasi-one-dimensional charge-density-wave (CDW)
insulators and proposed an intrinsic Floquet sideband mechanism arising from the sliding condensate. Here we develop the complete theoretical framework underlying this proposal. We provide an exact Floquet diagonalization of the uniformly sliding CDW, yielding split gap edges and a ladder of Floquet sidebands with explicit
unitary transformation and spectral functions. Using this exact solution, we formulate weak-probe tunneling spectroscopy and show that the local Floquet spectrum naturally yields 1/I oscillations as successive sideband edges cross a fixed contact chemical potential. Matching the observed oscillation period to theory reveals that the macroscopic current must percolate through a highly localized coherent filament, with effective channel number N_eff ~ 480, nearly two orders of magnitude smaller than the
geometric chain count N_geom ~ 3 x 10^4. This filamentary confinement is essential: achieving the required sliding frequency uniformly across the bulk would demand prohibitively large currents and induce thermal dephasing. Furthermore, using a segmented multiterminal model, we show that inelastic phase-slip dephasing near the contacts explains the observed suppression of oscillation visibility on outer voltage probes. We also contrast the persistent-current-driven multiterminal geometry with a homogeneous voltage-biased two-terminal reference calculation. Our results establish a rigorous nonequilibrium transport framework for the observed 1/I oscillations and highlight a universal spatial-to-temporal conversion mechanism in which the insulating gap protects Floquet coherence, offering a design principle for intrinsically driven
quantum devices.
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Materials Science
Unraveling the Origin of Ferrimagnetic Signatures in (Fe,Mn,Ga)2O3 Bixbyites: The Role of Structurally-Undetectable Spinel Impurities
Evgeniya Moshkina, Yuriy Knyazev, Ekaterina Smorodina et al. (+12 more)
The cubic Fe2-xMnxO3 is an intriguing material that has recently been investigated for various applications, including lithium-ion battery anodes, catalysts, energy storage media, humidity sensors, and photocatalysts. Despite its wide range of promising applications, the
magnetic properties of Fe2-xMnxO3 remain controversial, with different sources reporting conflicting information regarding the type of
magnetic ordering, phase transition temperature, and
magnetic moment of this compound. This work presents a study of the
magnetic state of three Fe2-xMnxO3:Ga solid solutions with varying Mn:Fe:Ga ratios, along with one gallium-free Fe2-xMnxO3 reference sample. We performed a detailed analysis of the actual chemical composition and
crystal structure of the synthesized samples using energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS) to evaluate compositional differences. The
magnetic states of the three Fe2-xMnxO3:Ga samples and the gallium-free Fe2-xMnxO3 were investigated using magnetometry and Mossbauer spectroscopy. The low-temperature
magnetic anomalies were found to be more consistent with
spin-glass-like freezing than with conventional long-range
antiferromagnetic ordering. Although variations in
magnetic behavior were observed and found to depend on composition and the cooling rate during synthesis, our results demonstrate that these factors do not account for the drastically different
magnetic properties reported for similar bixbyite-type
oxides. Instead, the apparent room-temperature ferrimagnetism observed in one sample is most likely extrinsic and can be attributed to a trace spinel-type
impurity phase, as supported by magnetizations and ESR measurements. Thus, the origin of these discrepancies lies primarily in the chemical purity of the samples and, to a significant extent, in the synthesis technique employed.
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All authors Evgeniya Moshkina, Yuriy Knyazev, Ekaterina Smorodina, Oleg Bayukov, Maxim Molokeev, Evgeniy Khramov, Andrey Kartashev, Ruslan Batulin, Mikhail Cherosov, Dmitriy Velikanov, Evgeniy Eremin, Mikhail Rautskii, Dieter Kokh, Mikhail Platunov, Leonard Bezmaternykh
Materials Science
Fermi energy Weyl nodes in $\mathbf{AM}$Te$_4$ ($\mathbf{A}$=Ta, Nb, $\mathbf{M}$=Ir, Rh)
Shivam Parasar, Jeroen van den Brink and Rajyavardhan Ray
Key aspects of the
quantum oscillations and magnetoresistance in Weyl semimetals $AM$Te$_4$ ($A$=Nb,Ta, $M$=Rh, Ir) persist as open questions, obscuring the link between their topological electronic structure and practical implementations. Employing a generalised search procedure, we carry out a comprehensive scan of WPs accounting for all the subbands close to the
Fermi energy, and show that this dramatically alters the WP landscape in these compounds. In particular, we predict these compounds to feature WPs within a few meV of the
Fermi energy which significantly influence their properties. Remarkably, most of the considered compounds host WPs of more than one type, including NbRhTe$_4$ which hosts type-I, II and III Weyl points. Our comparative analysis of structure and fidelity of computational parameters/models not only provides a detailed mapping of the complex electronic structure in these compounds, but also clarifies
quantum oscillations and magnetoresistance observations in this family, bridging the gap between theory and experiments and offering a framework for precise tunability of WPs.
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Materials Science · Cross-listed from cs.AI
XDecomposer: Learning Prior-Free Set Decomposition for Multiphase X-ray Diffraction
Hanyu Gao, Bin Cao, Yunyue Su et al. (+2 more)
Multiphase powder X-ray diffraction (PXRD) analysis remains a fundamental bottleneck in structure identification, as real-world synthesis often produces complex mixtures whose constituent phases (components) cannot be reliably disentangled. While recent advances in representation-based
crystal retrieval and generation suggest the possibility of inferring structures directly from PXRD, existing approaches largely assume single-phase inputs and break down in multiphase settings. Here, we present XDecomposer, a prior-free framework for joint decomposition and identification of multiphase XRD patterns without requiring candidate phase lists, structural templates, or prior knowledge of phase number. We formulate multiphase diffraction analysis as a set prediction problem, where the model infers an unordered set of phase-resolved components, their mixture proportions, and corresponding structural representations within a unified architecture. A phase-query-driven decomposition mechanism, together with diffraction-consistent physical reconstruction, enables accurate source separation while preserving crystallographic fidelity. Extensive experiments on both simulated and experimental
datasets show that XDecomposer substantially improves reconstruction accuracy and phase identification across diverse chemical systems, while maintaining strong generalization to unseen mixtures. These results provide a practical route toward data-driven, source-resolved multiphase XRD analysis and reduce long-standing dependence on prior-guided iteratively phase matching. The code is openly available at https://github.com/Licht0812/XDecomposer
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All authors Hanyu Gao, Bin Cao, Yunyue Su, Tong-Yi Zhang, Qiang Liu