Peer Revenue Returns subject to peer review

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Condensed Matter

cond-mat Watch Condensed Matter

Wednesday 15 April

Strongly Correlated Electrons

Revisiting 9Be Nuclear Magnetic Resonance in UBe13: Itinerant-Localized Duality and Possible Fermi Surface Reconstruction at High Magnetic Field

Rintaro Matsuki, Shoko Minami, Hisashi Kotegawa et al. (+5 more)

We report on new results of 9Be nuclear magnetic resonance (NMR) measurements conducted on a single crystal of the heavy fermion superconductor UBe13. Our previous 2007 study [J. Phys. Soc. Jpn. 76 204705 (2007)] determined NMR and electric field gradient (EFG) parameters that successfully reproduced the NMR spectra at low magnetic fields. However, these parameters did not accurately describe the angular dependence of the NMR spectra at high magnetic fields. To address this discrepancy, we have now performed a more comprehensive investigation, measuring the magnetic field dependence of the 9Be-NMR spectra across a field range of 0.5 T to 8 T, as well as the magnetic field angle dependence at 0.5 T and 6 T. Through detailed simulations that take into account the non-symmorphic space group of UBe13, we have determined a new set of parameters capable of reproducing the complex NMR line profiles observed at high magnetic fields. Notably, our analysis reveals the significant influence of classical dipolar fields. A comparison between the Knight shift (KS) and the classical dipolar shift provides microscopic supporting evidence for the nature of an itinerant-localized duality in UBe13. Furthermore, the magnetic field dependence of the KS exhibits anomalies around 6 T, suggesting a reconstruction of a part of the multiple Fermi surfaces in the high magnetic field region.
Read the full abstract

All authors Rintaro Matsuki, Shoko Minami, Hisashi Kotegawa, Hisatomo Harima, Yoshinori Haga, Etsuji Yamamoto, Yoshichika Onuki, Hideki Tou

Soft Condensed Matter

Various phases of active matter emerging from bacteria and their implications

Kazumasa A. Takeuchi and Daiki Nishiguchi

In this perspective article, we discuss bacterial populations as a model system of active matter. It allows for the exploration and characterization of various phases of active matter and brings rich implications for both physics and biology. Specifically, we focus on active gas, active liquid, active glass and active liquid crystal states observed in bacterial populations and describe how these differ from their thermal counterparts. A few future directions are also discussed that will deepen the physical interest in active matter as a new type of material, with its implications for several life phenomena observed in bacterial populations and other biological systems.
Read the full abstract

Strongly Correlated Electrons

Anomalous Low-temperature Magnetotransport in Kagome Metal CsCr$_3$Sb$_5$ under Pressure

Zikai Zhou, Wenyan Wang, Deng Hu et al. (+5 more)

As a unique kagome superconductor displaying clear signatures of strong electronic correlations, CsCr$_3$Sb$_5$ has drawn much attention. Its rich temperature-pressure phase diagram features intertwined orders including pressure-induced superconductivity and two density-wave-like phases, making it an outstanding platform to explore the complex coexistence and competition of multiple quantum orders. At around 30 K, which we designate as $T_3$, a possible anomaly manifesting as a hump in the resistivity has been observed, yet its nature remains largely unexplored due to limited supporting evidence from other probes. Here, we conducted systematic magnetotransport experiments under hydrostatic pressure to investigate the nature of this anomaly. Our results reveal an abundance of intriguing magnetotransport signatures below $T_3$, including a non-trivial temperature dependence of the Hall coefficient, multi-band characteristics, and pressure-enhanced anomalous-Hall-like effect. These signatures bear resemblance to those observed in the charge-density-wave state in the sister compound CsV$_3$Sb$_5$. These findings suggest the possibility of an additional, exotic electronic order in CsCr$_3$Sb$_5$, calling for further detailed investigations.
Read the full abstract

All authors Zikai Zhou, Wenyan Wang, Deng Hu, Zheyu Wang, Ying Kit Tsui, Tsz Fung Poon, Zhiwei Wang, Swee K. Goh

Mesoscale and Nanoscale Physics

Emergent topological phase from a one-dimensional network of defects

Rahul Singh, Ritajit Kundu, Arijit Kundu et al. (+1 more)

Symmetry-protected topological phases of matter, characterized by non-trivial band topology, are spectrally gapped and show non-trivial boundary phenomena. Here, we show that scattering states when interjected by an array of periodically modulated defects can result in emergent topological phases whose properties can be tuned by modulating the defect strengths. We dub this the Su-Schrieffer-Heeger network. We show that a scattering-matrix network model can capture the emergent symmetries and nontrivial winding of the quasienergy bands, which lead to distinct transport signatures and can be further periodically driven to realize a robust Thouless charge pump. We show that a microscopic lattice model embedded with a defect superlattice yields Bloch minibands that directly map to the network problem. We further verify that the physics we report is stable to disorder and point out concrete experimental solid-state platforms where it is readily realizable. Our work, in contrast to engineering atomic Hamiltonians, shows that defect engineering on metallic platforms can lead to emergent topological phases of quantum matter.
Read the full abstract

All authors Rahul Singh, Ritajit Kundu, Arijit Kundu, Adhip Agarwala

Mesoscale and Nanoscale Physics

Coherent control of thermal transport with pillar-based phononic crystals

Tatu A. S. Korkiamäki, Tuomas A. Puurtinen, Mikko Kivekäs et al. (+4 more)

Two-dimensional phononic crystals (PnCs) formed by a periodic array of holes in a suspended membrane have previously been used to coherently control thermal conductance at low temperatures by modifying the phonon dispersion, thereby altering the phonon group velocities and the density of states. Here, in contrast, we demonstrate that PnCs formed by a periodic array of Al pillars on an uncut \SiN membrane can also be used to achieve similar coherent control. We have measured and simulated the thermal conductance of four pillar-based PnCs with different lattice constants ranging from 0.3 to 5 $\mu$m at sub-Kelvin temperatures, showing a strong up to an order of magnitude reduction in thermal conductance compared to an unaltered membrane. For the larger lattice constants $> 1 $ $\mu$m, however, the experiments do not agree with the coherent theory simulations, which we interpret as a breakdown of coherence induced by increasingly effective diffusive scattering due to the roughness of the Al pillar surfaces.
Read the full abstract

All authors Tatu A. S. Korkiamäki, Tuomas A. Puurtinen, Mikko Kivekäs, Teemu Loippo, Adam Krysztofik, Bartlomiej Graczykowski, Ilari J. Maasilta

Disordered Systems and Neural Networks · Cross-listed from cs.IT

Phase transition in compressed sensing using log-sum penalty and adaptive smoothing

Keisuke Morita, Federico Ricci-Tersenghi and Masayuki Ohzeki

In many real-world problems, recovering sparse signals from underdetermined linear systems remains a fundamental challenge. Although $\ell_1$ norm minimization is widely used, it suffers from estimation bias that prevents it from reaching the Bayes-optimal reconstruction limit. Nonconvex alternatives, such as the log-sum penalty, have been proposed to promote stronger sparsity. However, maintaining their algorithmic stability is challenging. To address this challenge, we introduce an adaptive smoothing strategy within an approximate message passing framework to mitigate algorithmic instability. Furthermore, we evaluate the typical exact-recovery threshold for Gaussian measurement matrices using the replica method and state evolution. The results indicate that the adaptive method achieves exact recovery over a broader region than $\ell_1$ norm minimization, although metastable states hinder reaching the information-theoretic limit.
Read the full abstract

Soft Condensed Matter

Coarse-Grained Model of the Sodium Dodecyl Sulfate Anionic Surfactant Based on the MDPD–Martini Force Field

Luís H. Carnevale, Gabriela Niechwiadowicz and Panagiotis E. Theodorakis

The sodium dodecyl sulfate (SDS) surfactant is widely used in various applications, such as household products (e.g., shampoos, toothpaste, detergents, and cleaning products) and food manufacturing (e.g., emulsifiers). To investigate its properties via computer simulation, various models have been developed, including coarse-grained (CG) models that are suitable for capturing a surfactant's self-assembly and fundamental properties for aqueous systems with a surfactant, such as surface tension. Here, we present a CG model for SDS/water systems for many-body dissipative particle dynamics (MDPD), which is based on the MDPD–Martini force field (FF). In the model, charged groups, namely, the SDS sulfate headgroup and the sodium cation, are explicitly modeled following the standard mapping of the Martini force field for molecular dynamics (MD), while the remaining interactions have been obtained from previous MDPD–Martini models for lipid systems, thus demonstrating their transferability. Various relevant system properties, such as the coherent scattered intensity and surfactant distribution at the liquid–vapor surface, are investigated, and results are compared to those obtained by MD simulations and experiments at different surfactant concentrations. Our findings indicate that MDPD–Martini models can offer a credible alternative to MD–Martini models for systems with explicit charges as shown here for SDS. Moreover, MDPD–Martini models reproduce nicely the experimental surface tension isotherm, in contrast to MD simulations. In view of the transferability of the MDPD–Martini interactions, the model parameters of this study can be tested and used to simulate a wider range of soft-matter systems.
Read the full abstract

Materials Science · Cross-listed from physics.app-ph

Confinement-controlled pathways to complex skyrmionic textures in Co/W/Pt multilayers

Y. Al Sadi, R. Sbiaa, W. Al Saidi et al. (+9 more)

Magnetic skyrmions and higher-order topological spin textures offer rich opportunities for multi-level information encoding, yet their deterministic stabilization and transformation under geometric confinement at room temperature remain poorly understood. Here, we demonstrate that geometric confinement acts as a robust and universal control parameter that governs a hierarchical transformation pathway of chiral spin textures in Pt/Co/W multilayer micro-tracks. As the confinement increases, extended labyrinth domains fragment into isolated skyrmions, followed by the systematic suppression of skyrmion pairs and the preferential stabilization of compact higher-order textures. We find that confinement strongly enhances the formation of skyrmioniums via recombination and promotes their subsequent evolution into uniform skyrmion bags by capturing additional skyrmions. Statistical analysis reveals a confinement-driven redistribution of topological populations, with skyrmion bags emerging as the dominant state in the narrowest tracks. Supported by micromagnetic simulations, our results establish geometric confinement as a deterministic selector of complex topological textures and reveal a previously unexplored route for engineering higher-order skyrmionic states at room temperature. These findings provide a scalable materials strategy for multistate skyrmion-based spintronic and memory architectures.
Read the full abstract

All authors Y. Al Sadi, R. Sbiaa, W. Al Saidi, M. Souier, G. Lezier, O. Marbouh, M.T.Z. Myint, Y. Dusch, S. Al Harthi, A. Talbi, N. Tiercelin, S. N. Piramanayagam

Disordered Systems and Neural Networks

Dynamics of spin glasses in two dimensions

Hongze Li, Raymond L. Orbach and Gregory G. Kenning

Spin glass dynamics is a strong function of spatial dimensionality $D$. The lower critical dimension is close to 2.5, so that, in two dimensions, the condensation temperature $T_\text{g}=0$, and only fluctuations are present at finite temperatures. However, by using thin film multilayers, one can explore the dynamics in both $D=3$ and $D=2$ dimensions. Spin glass thin film multilayers transition from $D=3$ dynamics at short to intermediate times to $D = 2$ dynamics at long times. Correlation lengths of CuMn 4.5 nm multilayers at long times are shown to be grow more rapidly in $D=2$ as compared to $D=3$, and for the longest measurement time, experimentally reach equilibrium in qualitative agreement with simulations.
Read the full abstract

Mesoscale and Nanoscale Physics

Emergence of Nontrivial Topological Magnon States in Skyrmionium Lattices with Zero Topological Charge

Xingen Zheng, Ping Tang, Xuejuan Liu et al. (+3 more)

We predict the emergence of nontrivial topological magnon states in the skyrmionium lattice with zero topological charge. We propose the concept of weighted magnetic flux, which provides a clear physical picture for this anomalous phenomenon. We also map the skyrmionium lattice onto the Haldane model, offering an alternative framework for interpreting this. Our findings challenge the conventional wisdom that such states are linked to nonzero topological charge in skyrmion lattices, offering a new perspective in topological magnonics. To facilitate experimental validation, we propose two methods for preparing the skyrmionium lattice and calculate the induced magnon thermal Hall conductivity, which is a key indicator in transport measurements.
Read the full abstract

All authors Xingen Zheng, Ping Tang, Xuejuan Liu, Zhixiong Li, Peng Yan, Hao Wu

Mesoscale and Nanoscale Physics

Sub-nm range momentum-dependent exciton transfer from a 2D semiconductor to graphene

Aditi Raman Moghe, Delphine Lagarde, Sotirios Papadopoulos et al. (+11 more)

Heterostructures made from atomically thin semiconductors (here MoSe$_2$) and graphene are uniquely poised to investigate photoinduced charge and energy transfer in the 2D limit. Here, using picosecond time-resolved photoluminescence spectroscopy at cryogenic temperatures on two types of MoSe$_2$/graphene heterostrutures, we unveil key features of the underlying mechanisms. First, the shortening of the MoSe$_2$ bright exciton lifetime is marginally affected by the number of graphene layers to which MoSe$_2$ is coupled. Second, exciton transfer vanishes when a sub-nm thick spacer of hexagonal boron nitride decouples MoSe$_2$ from graphene. These results indicate that charge tunneling govern bright exciton relaxation in MoSe$_2$/graphene and that longer-range, Förster-type energy transfer (FRET) does not affect bright excitons. However, sub-ps FRET to graphene accelerates the relaxation of “hot” excitons formed upon optical excitation, leading to photoluminescence quenching factors that exceed expectations based on the shortening of the bright exciton lifetime. Our work has direct implications for energy harvesting and funneling using van der Waals heterostructures.
Read the full abstract

All authors Aditi Raman Moghe, Delphine Lagarde, Sotirios Papadopoulos, Etienne Lorchat, Luis E. Parra López, Loïc Moczko, Kenji Watanabe, Takashi Taniguchi, Michelangelo Romeo, Maxime Mauguet, Xavier Marie, Arnaud Gloppe, Cédric Robert, Stéphane Berciaud

Materials Science

Probing local coordination and halide miscibility in single-, double-, and triple-halide perovskites using EXAFS

Sonia S. Mulgund, Esther Y.-H. Hung, Leslie Bostwick et al. (+4 more)

Lead-halide perovskites are a promising material platform as semiconductors in next-generation solar cells because of their solution processability, defect tolerance, and tunable optoelectronic properties. Mixed iodide-bromide perovskite compositions are attractive as wide bandgap absorbers but suffer from significant operational instabilities. Incorporation of chloride to form triple-halide perovskites has been shown to improve both stability and performance; however, the extent of halide miscibility and chloride incorporation remain poorly understood. While bulk metrics such as diffraction-derived lattice parameters and optical bandgap can confirm single-phase behavior, they do not establish homogeneous mixing on the halide site. Here, we use cryogenic X-ray absorption spectroscopy (XAS) to directly probe local lead-halide coordination across single-, double-, and triple-halide perovskite compositions. We show formation of a single-phase triple-halide perovskite whose miscibility is mediated by bromide content. We identify signatures of halide mixing from the Pb L3-edge EXAFS of mixed double- and triple-halide perovskites using both quantitative fits and Cauchy wavelet transforms. Finally, using wavelet transforms of the Br K-edge EXAFS, we demonstrate halide intermixing on the single PbX6 octahedron level, exploiting forward-scattering amplified third-shell halide-bromide interactions. These results are a step forward in the understanding of local structure that is required to fully describe and optimize halide incorporation for novel perovskite compositions.
Read the full abstract

All authors Sonia S. Mulgund, Esther Y.-H. Hung, Leslie Bostwick, Ashley Galbraith, Owen M. Romberg, Justus Just, Rebecca A. Belisle

Strongly Correlated Electrons

Extreme Terahertz Nonlinear Phononics by Coherence-Imprinted Control of Hybrid Order

Liang Luo, Avinash Khatri, Martin Mootz et al. (+12 more)

Coherent control of quantum materials has progressed along two major fronts: nonlinear phononics, which reshapes lattices to induce emergent states, and Floquet engineering, which tailors electronic band reconstruction via time-periodic driving. Both mechanisms face fundamental limitations at terahertz (THz) frequencies: phononic nonlinearities are intrinsically weak in standard lattices, while electronic Floquet states are often constrained by rapid decoherence upon light-off and by a scarcity of coherence-resolved, multi-correlation probes beyond (quasi-)stationary band structures. Here we report an extreme THz nonlinear-phononics mechanism in $\text{Ta}_\text{2}\text{NiSe}_\text{5}$, where a highly susceptible non-equilibrium electronic correlation bath dramatically amplifies lattice nonlinearities under coherent driving. Utilizing THz two-dimensional spectroscopy as a coherence-tomography tool, we resolve an exceptionally rich landscape of approximately 30 distinct multi-order quantum pathways, including high-harmonic phonon generation, multi-quantum coherences, and multi-wave anharmonic cross-mode mixing. The density and complexity of this extreme manifold establishes a new benchmark for THz nonlinear phononics, as the multi-order quantum pathways surpass the limits of conventional lattice responses. These high-order signals collapse above ~100~K, defining an electronic correlation scale of a coherence-imprinted hybrid electronic-phonon order that governs the sustainability of high-order quantum correlations and nonlinear pathways beyond linear and equilibrium responses. Our results establish a route for correlation-boosted, phonon-anchored periodic Hamiltonian engineering and for certifying such periodically-driven states via multi-correlation coherence tomography.
Read the full abstract

All authors Liang Luo, Avinash Khatri, Martin Mootz, Tao Jiang, Liu Yang, Zijing Chen, Chuankun Huang, Zhi Xiang Chong, Joongmok Park, Ilias E. Perakis, Zhiwei Wang, Yugui Yao, Dao Xiang, Yong-Xin Yao, Jigang Wang

Soft Condensed Matter

Universal Scaling of Freezing Morphodynamics in Polymer Solution Droplets

Nicolas G. Ulrich, Pravin P. Aravindhan, Olivia Berger et al. (+2 more)

Freezing of complex fluids is central to a wide range of natural and technological processes, where the interplay between heat transport, solute redistribution, and interfacial deformation gives rise to complex morphologies. Unlike simple liquids, polymer solutions exhibit strongly coupled transport and rheological properties that evolve dynamically during solidification, making their freezing behavior difficult to predict. Here, we examine the freezing of polymer solution droplets spanning dilute to entangled regimes. We find that droplet morphology and freezing dynamics in viscous solutions are governed by a single dimensionless parameter, the Capillary–Lewis number, which captures the competition between viscous stresses, capillarity, and solute transport. Circularity, radial deformation, and freezing time collapse onto a master curve spanning nine orders of magnitude, revealing a transition near unity corresponding to the point at which solute diffusion can no longer relax concentration gradients ahead of the freezing interface. This collapse holds across distinct polymer chemistries within the viscous fluid regime, while deviations emerge when the material exhibits elastic-dominated response ($G' > G''$), indicating the breakdown of purely transport–capillary control. These results establish a minimal transport–mechanics framework linking solute redistribution to interfacial deformation during freezing polymer solutions.
Read the full abstract

All authors Nicolas G. Ulrich, Pravin P. Aravindhan, Olivia Berger, Bryan S. Beckingham, Jean-François Louf

Soft Condensed Matter

Dynamical Theory of Elastic Synchronization of Cardiomyocytes

Akinari Tomiie and Nariya Uchida

We study synchronization of two cardiomyocytes mediated by elastic interactions through the substrate. Modeling each cell as an oscillating force dipole governed by a Rayleigh-type equation, we derive an effective mechanical coupling from the elastic response of the surrounding medium. Using phase reduction theory, supported by direct numerical simulations, we obtain a dynamical phase description for two cardiomyocytes that predicts geometry-dependent selection of synchronized states. Depending on the mutual orientation, the cells robustly converge to either in-phase or anti-phase beating, yielding an orientation-dependent state map with a nontrivial state boundary. The synchronization time also depends strongly on the distance and mutual orientation of the cells. These results bridge earlier energetic two-body theory and dynamical single-cell theory, and provide a dynamical framework for elastic synchronization of cardiomyocytes.
Read the full abstract

Other Condensed Matter · Cross-listed from quant-ph

Dynamics of wavepackets and entanglement in many-body kicked rotors under quantum resonance

Yangshuo Zhou and Jiao Wang

We investigate a many-body interacting system of quantum kicked rotors, where each rotor resides in its respective quantum resonance. Rich many-body dynamics are found to emerge from the interplay between the principal and secondary resonances. In particular, for both the wavepacket and bipartite entanglement entropy, we analytically demonstrate three distinct dynamical regimes – quadratic spreading (growth), period-2 oscillation, and their hybrid – governed by the respective symmetries of the relevant potentials. Based on these symmetries, the connection between the wavepacket and the entanglement dynamics is illustrated. Other related issues are also discussed, including higher-order resonance effects, the robustness of the predicted dynamical behaviors, extension to many-body kicked tops, and relevance to experimental studies.
Read the full abstract

Other Condensed Matter · Cross-listed from physics.optics

Topological routing in Chern insulators

Mark J. Ablowitz, Justin T. Cole and Sean D. Nixon

Chern insulator systems are realizable in numerous physical systems and can support robust nonreciprocal transmission of energy. A routing functionality constructed from two counter-oriented Chern insulator regions, using coupled Haldane type systems is proposed. By adjusting the strength of a magnetic field and the frequency of an antenna source, it possible to steer the flow of energy: completely to the left, completely to the right, or split. Alternatively, two sources can be used to direct the flow of energy. This formulation has the potential to serve as a robust and reconfigurable component in optical transmission.
Read the full abstract

Quantum Gases

Attractive Multidimensional Condensates–Experiments

Hikaru Tamura and Chen-Lung Hung

Experiments on attractive Bose-Einstein condensates (BECs) have unlocked many intriguing out-of-equilibrium dynamics through the interplay between matter-wave dispersion and nonlinear attractive interaction. Competition between these effects leads to fascinating phenomena such as wave collapse, modulational instability, and formation of multidimensional bright solitons. This chapter reviews experimental studies on attractive condensates, with a primary focus on alkali atoms featuring two-body contact interactions. We review recent experimental advances in optical trapping and interaction control techniques, which have enabled new studies on attractive condensates in three and also in lower dimensions. Specifically, we discuss pioneering and recent experimental observations on the dynamics and stability of attractive BECs, including the formation of bright solitons, their collisions, and excitations in quasi-one-dimensional traps. Recent observations of the elusive two-dimensional Townes solitons and vortex solitons are also discussed in this Chapter. We then highlight an experimental technique revealing the nonclassical signatures of modulational instability in an attractive condensate.
Read the full abstract

Mesoscale and Nanoscale Physics

Loss Mechanisms in Cryogenic Microwave Epitaxial AlN Resonators

Hemant Gulupalli, Navnil Choudhury, Jiacheng Xie et al. (+6 more)

Epitaxial aluminum nitride (AlN) thin-film bulk acoustic resonators (FBARs) enable low loss filtering for future 6G systems. They also provide a compact approach for qubit sensing at cryogenic temperatures. However, these devices are rarely characterized systematically from room temperature to cryogenic temperatures, and the mechanisms that limit their cryogenic performance remain unclear. In this work, we study a 15.6 GHz epitaxial AlN FBAR from room temperature to cryogenic temperatures to identify losses from the AlN film and those introduced by the electrodes, anchors, and other device layers. Small signal RF measurements from 294 K down to 6.5 K show an increase in the raw Qmax from 363 to 1589. A temperature dependent model that includes phonon phonon scattering, thermoelastic damping, dielectric loss, electrical loss, and anchor loss helps explain the measured Q(T) trend and identifies a transition from the Landau Rumer to the Akhiezer regime near 270 K. The model indicates that acoustic energy leakage through the anchors limits Q at cryogenic temperatures, while electrical loss dominates at higher temperatures. These results point to two routes toward higher cryogenic Q: better acoustic isolation of the anchors and lower loss electrodes, including superconducting electrodes. Improved anchor design benefits both high frequency 6G filters and cryogenic quantum microwave circuits, while superconducting electrodes are particularly useful for cryogenic operation.
Read the full abstract

All authors Hemant Gulupalli, Navnil Choudhury, Jiacheng Xie, Yufeng Wu, Huili Grace Xing, Hong X. Tang, Debdeep Jena, Kanad Basu, Wenwen Zhao

Tuesday 14 April

Soft Condensed Matter

Concentration-dependent shear response of multi-chain amphiphilic block copolymer self-assemblies

Ehsan Kamali Ahangar, Dominic Robe and Elnaz Hajizadeh

Amphiphilic block copolymers self-assemble into diverse nanoscale morphologies with significant implications for drug delivery. This work presents systematic Brownian dynamics simulations of multi-chain diblock and triblock copolymers across dilute and semi-dilute unentangled regimes, hydrophobic fractions, f of 0-1, and shear rates of 0-0.1 1/ns. In the dilute regime, quiescent conditions yield spherical micelles evolving to cigar-like structures at shear rate ~0.01 1/ns and fragmenting at higher shear; varying f produces dispersed chains (f=0), cigar-like (f=0.25), short cylindrical (f=0.5), and gnarled or worm-like (f=0.75) micelles, culminating in sheet-like phase-separated structures (f=1). While, in the semi-dilute regime, shear drives collective reorganisation toward sheet-like morphologies at moderate rates before fragmentation; the f-dependent progression yields cigar-like (f=0.25), sheet-like (f=0.5), and necklace micelles (f=0.75), with larger phase-separated domains at f=1. Rheological characterisation reveals a universal architectural inversion between equilibrium and flow conditions: diblocks show higher equilibrium viscosity while triblocks maintain superior viscosity under flow via bridging networks. Aggregation number scaling exponents of alpha=0.833 in dilute, consistent with star-to-crew-cut bounds of 0.8 to 1.0, and alpha=1.07 in semi-dilute confirm the concentration-driven transition between regimes. Viscoelastic analysis establishes universal non-terminal power-law scaling across all conditions, governed by micellar relaxation dynamics independent of concentration or topology. These findings provide valuable insights into tailoring the injectability and flow behaviour of block copolymers in drug delivery formulations.
Read the full abstract

Statistical Mechanics · Cross-listed from physics.flu-dyn

Effect of gap width on turbulent transition in Taylor-Couette flow

Chang-Quan Zhou, Hua-Shu Dou, Lin Niu et al. (+1 more)

Simulations of the transitional flow in Taylor-Couette configuration are carried out to study the effect of the gap width on turbulent transition. The research results show that, under the same radius and the rotating speed of the inner cylinder, as the gap width increases, the flow becomes more stable. It is discovered that the average velocity distribution in the gap approaches the free vortex flow as the width increase and the stability of the flow is enhanced. It is found that, as the gap width increases, the maximum of the energy gradient function (from the energy gradient theory) in the gap decreases, which delays the turbulent transition. As such, the larger the gap width, the later the transition occurs. As the gap width increases, the Reynolds number based on the gap width alone is not able to characterize the flow behavior in Taylor-Couette flows, and the effect of the radius ratio should be taken into account.
Read the full abstract

All authors Chang-Quan Zhou, Hua-Shu Dou, Lin Niu, Wen-Qian Xu

Statistical Mechanics · Cross-listed from quant-ph

Scrambling of Entanglement from Integrability to Chaos: Bootstrapped Time-Integrated Spread Complexity

M. Süzen

A physical relationship for the combination of scrambling via spread complexity and entanglement is characterized by the fidelity of quantum unitary dynamics. Time-integrated quantities for the degree of quantum ergodicity capture state spreading from initial to late times under physically plausible operator perturbations. Selecting maximally entangled state as a initial condition evaluates the scrambling of entanglement in this setting. For this reason, we utilize the Rosenzweig-Porter ensembles across different ergodic regimes. Computed integrated spread complexity and associated integrated quantum state fidelity display a monotonic inverse relationship for maximally entangled states from integrability to chaos. Information bounds in non-local high-energy systems and holographic scrambling can be evaluated with this approach.
Read the full abstract

Soft Condensed Matter

A Unified Glassy Rheology for Granular Matter

Zhikun Zeng, Jiazhao Xu, Hanyu Li et al. (+14 more)

Granular flows are ubiquitous in nature and industrial applications, yet a complete continuum theory remains a long-standing challenge. The leading empirical approach, {\mu}(I) rheology, lacks microscopic foundations and becomes multivalued in dense, slowly sheared flows where nonlocal corrections are required. Exploiting state-of-the-art high-speed X-ray tomography to investigate microscopic dynamics of dense granular flows in a Couette geometry, we establish a new, universal constitutive law spanning quasi-static to inertial regimes based on structural relaxation, resolving the fundamental difficulty in the original {\mu}(I) framework. By further establishing a non-equilibrium statistical framework for granular flows, we demonstrate an intrinsic analogy between driven granular matter and hard-sphere liquids owing to their identical Carnahan-Starling equation of state, naturally explaining our rheological approach and the emergence of glassy behaviors. Our framework unifies granular rheology with the broader physics of disordered systems and provides a complete, microscopically-based theoretical framework for dense granular flow.
Read the full abstract

All authors Zhikun Zeng, Jiazhao Xu, Hanyu Li, Shiang Zhang, Houfei Yuan, Chijin Zhou, Xueliang Dai, Haiyang Lu, Xin Wang, Jun Zhao, Yonglun Jiang, Zhuan Ge, Gang Huang, Chengjie Xia, Jianqi Sun, Yan Xi, Yujie Wang

Mesoscale and Nanoscale Physics · Cross-listed from hep-th

Heat-Kernel approach to the Atiyah–Singer Index of Non-Hermitian Dirac Operators

João Pedro Breveglieri da Silva and Dmitri Vassilevich

If an operator $H$ anticommutes with a chirality operator $\Gamma_*$ such that $\Gamma_*^2=1$, the null space of $H$ can be decomposed in a direct sum of two spaces having positive and negative chiralities, respectively. When both spaces are finite dimensional, one can define an index, $\mathrm{Ind}(\Gamma_*,H)$, as the difference of dimensions of these two spaces. The key issue is whether $\mathrm{Ind}(\Gamma_*,H)$ is topologically protected, i.e., whether it remains constant under smooth variations of the parameters and background fields entering $H$. For Hermitian Dirac operators, topological protection of the index is guaranteed by the Atiyah–Singer theorem. In this paper, by using the heat kernel methods, we show that $\mathrm{Ind}(\Gamma_*,H)$ is topologically protected also for non-hermitian operators $H$ as long as they are diagonalizable and satisfy some ellipticity conditions. The index is given by a heat kernel coefficient which is an integral of a local expression depending on background fields.
Read the full abstract

Materials Science

Finetuning-Free Diffusion Model with Adaptive Constraint Guidance for Inorganic Crystal Structure Generation

Auguste de Lambilly, Vladimir Baturin, David Portehault et al. (+4 more)

Generative diffusion models have emerged as powerful tools for the discovery of inorganic crystal structures, yet steering their sampling process toward user-defined physical and chemical objectives remains challenging. We present a computational framework that integrates adaptive constraint guidance into a pre-trained crystal diffusion model, enabling the generation of candidate structures that satisfy targeted structural and chemical requirements without model retraining. The approach incorporates differentiable constraint functions directly during sampling, providing an interpretable mechanism for expert-driven exploration of the crystal structure space. To assess the reliability of generated candidates, we introduce a multi-stage validation workflow combining descriptor-based analysis, duplicate removal, comparison with reference crystal databases, graph neural network energy prediction, and thermodynamic stability evaluation through convex-hull analysis. The framework is applied to several classes of inorganic compounds and to constraints involving atomic volume, local coordination environments, and near-neighbor structural motifs. Results demonstrate that adaptive guidance effectively redirects the sampling distribution toward structures exhibiting the desired characteristics while preserving chemical plausibility. Subsequent validation reveals which generated candidates remain viable after energetic and thermodynamic screening. The proposed methodology provides a practical and transparent strategy for incorporating expert knowledge into crystal generative models and establishes a general computational framework for constrained materials discovery.
Read the full abstract

All authors Auguste de Lambilly, Vladimir Baturin, David Portehault, Guillaume Lambard, Nataliya Sokolovska, Florence d'Alché-Buc, Jean-Claude Crivello

Materials Science

Uncovering the role of ionic doping in hydroxyapatite: The building blocks of tooth enamel and bones

Mahdi Tavakol, Jinke Chang, Cyril Besnard et al. (+4 more)

Hydroxyapatite (HAp) is the primary mineral component of various mineralized tissues in the human body, including bone and teeth, where it performs critical roles of structural support and load transmission. In the context of dental health, the two most crucial properties of HAp are mechanical stability, which ensures resistance to forces, and chemical stability, which preserves surface integrity in acidic environments. During early stages of human evolution, e.g. when teeth were used to crush uncooked food, mechanical stability was of paramount importance. However, with changes in diet and lifestyle, the principal origins of tooth damage and loss shifted towards bacterially mediated chemical attack, known as tooth decay, or caries. To enhance the chemical stability, ion doping has emerged as a particularly significant approach, and it lies at the focus of the present study. A Molecular Dynamics (MD) framework was developed to investigate the effects of ion doping on the chemical and mechanical stability of HAp and to identify optimal doping candidates. The framework combines conventional MD with Steered Molecular Dynamics (SMD), Thermodynamic Integration (TI) and uniaxial compression test simulations to provide comprehensive insights into the doping process. The findings revealed surface atoms as the most viable candidates for doping, as demonstrated by SMD and conventional MD simulations. Notably, TI calculations have identified magnesium ions as a better candidate among the ions considered here for enhancing the chemical stability of HAp. The results presented in this study offer valuable guidelines for synthesizing HAp-based substituent materials with properties tailored to meet the demands of modern dental applications such as implant coatings, enamel remineralization agents and restorative materials.
Read the full abstract

All authors Mahdi Tavakol, Jinke Chang, Cyril Besnard, Gabriel Landini, Richard M. Shelton, Jin-Chong Tan, Alexander M. Korsunsky

Mesoscale and Nanoscale Physics

Spin-Dependent Charge-State Conversion in NV Ensembles Mediated by Electron Tunneling

Neil B. Manson, Morgan Hedges, Michael S. J. Barson et al. (+3 more)

The nitrogen-vacancy (NV) center in diamond enables optical initialization and readout of its electronic spin, forming the basis of a wide range of quantum sensing and metrology applications. A central challenge in such measurements is the coexistence of two charge states, NV- and NV0: While detection protocols rely on the spin-dependent properties of NV-, fluorescence from NV0 does not carry useful contrast and is typically removed as background, reducing the available signal. Here, we show that the origin of NV0 emission depends strongly on the excitation wavelength in nitrogen-containing diamond. Using ensembles of NV centers with varying nitrogen concentrations, we compare excitation at the NV0 zero-phonon line (ZPL) at 575 nm with the commonly used 532 nm. We find that excitation at 575 nm generates NV0 predominantly through spin-selective tunneling from the excited state of NV- to nearby nitrogen donors, such that the NV0 emission follows the spin polarization of NV-. As a result, the NV0 fluorescence contributes to the measurable spin contrast, allowing the full fluorescence signal to be used for detection. This result opens opportunities for improved sensitivity in NV-based sensing applications.
Read the full abstract

All authors Neil B. Manson, Morgan Hedges, Michael S. J. Barson, Carlos A. Meriles, Ronald Ulbricht, Marcus W. Doherty

Soft Condensed Matter

Unified Microscopic Theory of Stress Relaxation, Structural Evolution, and Memory Effects in Dense Glass Forming Brownian Suspensions After Flow Cessation

Anoop Mutneja and Kenneth S. Schweizer

The re-solidification of amorphous solids after mechanically driven yielding from a nonequilibrium state is a fundamental soft matter science problem of broad relevance in materials science, with implications for material strength, processing, and printing-based additive manufacturing. We present a microscopic statistical mechanical theory that predicts in a unified manner the coupled time evolutions of structural and stress recovery following shear cessation from a mechanically prepared nonequilibrium state. The approach is built on recent advances in understanding activated dynamics in Brownian systems under both quiescent and startup continuous shear conditions. A particle-level microrheological model framework self-consistently incorporates stress generation, constraint softening due to external mechanical forces and structural deformation. After flow cessation, the theory captures the re-building of kinetic constraints and activation barriers over time that underlie structural recovery, stress relaxation, and re-solidification through dynamic relaxation and an elementary form of convective elastic backflow. The ideas are general for particle-based materials, and quantitatively applied to dense hard-sphere Brownian colloidal suspensions which also serve as a foundational paradigm for glass forming materials where thermal fluctuations are important. The theory properly captures the rich range of stress relaxation behaviors observed experimentally that evolve from exponential, to stretched exponential, to fractional power law in form with increasing packing fraction. A microscopic understanding is achieved of the emergence of apparent residual stresses on laboratory timescales, power-law endless aging, sigmoidal recovery of the elastic modulus, pre-shear-rate-dependent memory effects, and a two-step structural relaxation process that can become decoupled from stress relaxation.
Read the full abstract

Mesoscale and Nanoscale Physics

Geometric Spin Degeneracy in Spin-Orbit-Free Compensated Magnets

Seung Hun Lee, Yuting Qian, Xi Dai et al. (+1 more)

Compensated magnets with vanishing net magnetization can exhibit both pronounced spin splitting and unconventional band degeneracies. In altermagnets, such degeneracies are enforced by crystal and magnetic symmetries. In compensated ferrimagnets, however, they may arise even in the absence of the corresponding symmetry protection, raising a fundamental question about the origin of spin degeneracy in spin-orbit-free magnetic systems. Here, we develop a theoretical framework for spin-orbit-free compensated magnets in which spin degeneracies are protected by geometric constraints rather than by spin symmetry. We show that zero net magnetization imposes a strong condition for the emergence of nodes formed by formally spin-degenerate bands, even when no conventional spin symmetry is present. Our analysis, applicable in the weak-interaction regime, identifies a general mechanism for spin degeneracy beyond group-theoretical protection. The framework accounts for the unconventional spin degeneracies recently reported in compensated ferrimagnets and provides a unified description of band degeneracies across a broad class of magnetic phases with negligible spin-orbit coupling.
Read the full abstract

All authors Seung Hun Lee, Yuting Qian, Xi Dai, Bohm-Jung Yang

Quantum Gases

Long-lived revivals and real-space fragmentation in chains of multispecies Rydberg atoms

Jose Soto-Garcia and Natalia Chepiga

Arrays of Rydberg atoms provide a powerful platform for exploring constrained quantum dynamics and nonergodic many-body phenomena. While most work has focused on single-species systems, multispecies architectures offer additional interaction channels and enable new forms of dynamical constraints. We study the nonequilibrium dynamics of one-dimensional dual-species Rydberg chains of Cs and Rb atoms with species-dependent van der Waals interactions. Using large-scale matrix product state simulations, we show that the competition between intraspecies repulsion and interspecies attraction induces dynamical fragmentation, marked by the coexistence of extended frozen regions and localized oscillatory sectors. The frozen regions act as emergent barriers that isolate and protect coherent dynamics. In the purely repulsive regime, we find that species-selective quenches drive spontaneous fragmentation, leading to dynamically disconnected regions with irregular revivals. These phenomena are robust across interaction regimes, revealing a universal mechanism for fragmentation and establishing multispecies Rydberg arrays as a versatile platform for exploring nonequilibrium quantum dynamics beyond single-species systems.
Read the full abstract