Soft Condensed Matter
An elastic model of confined hydrogel particles with competing entropic and energetic networks
A. Huerta, L. A. Pérez and A. Trokhymchuk
This work presents an elastic model to study the interplay between entropic and energetic networks in confined hydrogel particles. We consider a quasi-two-dimensional system composed of spherical hydrogel beads confined in a circular container, where particle growth occurs through hydration. Based on experimental observations, an elastic potential is introduced to model interactions between particles and between particles and the confining wall. Computational simulations based on energy minimization identify the lowest-energy configurations adopted during growth. Analysis of the resulting energy landscapes reveals emergent self-organization, adaptability, and cooperativity arising from the competition between entropic and energetic networks.
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Materials Science · Cross-listed from cs.CV
Accurate identification and measurement of the precipitate area by two-stage deep neural networks in novel chromium-based alloys
Zeyu Xia, Kan Ma, Sibo Cheng et al. (+7 more)
The performance of advanced materials for extreme environments is underpinned by their microstructure, including the size and distribution of reinforcing phases. Chromium-based superalloys are a recently proposed alternative to conventional face-centred-cubic superalloys for high-temperature applications, such as Concentrated
Solar Power, and their development requires efficient measurement of precipitate volume fraction and size distribution from electron microscopy images. Traditional fixed-threshold image processing is sensitive to background noise, generalises poorly across materials, and requires substantial manual measurement effort. To address these bottlenecks, this study proposes DT-SegNet, an end-to-end two-stage deep learning scheme based on YOLOv5 and SegFormer for object detection and
segmentation in electron microscopy images. The approach combines the training efficiency of convolutional neural networks at the detection stage with the
segmentation accuracy of a
Vision Transformer. Numerical experiments show that DT-SegNet substantially outperforms state-of-the-art
segmentation tools offered by Weka and ilastik across metrics including accuracy, precision, recall, and F1-score. The model provides a useful tool for
alloy-development microstructure examinations and helps address the large
datasets associated with high-throughput
alloy development.
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All authors Zeyu Xia, Kan Ma, Sibo Cheng, Thomas Blackburn, Ziling Peng, Kewei Zhu, Weihang Zhang, Dunhui Xiao, Alexander J Knowles, Rossella Arcucci
Soft Condensed Matter
On the statistical theory of strong electrolytes and high-temperature plasmas: new applications of the work of Yukhnovskii and Kelbg
W. Ebeling and M. Holovko
Remembering here the work of two pioneers of the statistical physics of Coulomb systems, Günter Kelbg, and Ihor Yukhnovskii, we analyze their methods and give some new applications to ionic solutions and
quantum plasmas. In particular, we develop applications of the theory to strong electrolytes and to thermal high-temperature
plasmas at $T > 0^5$ K using the exponential interaction model. We show the strong structural similarity of these two classes of Coulomb systems, which physics is determined mostly by contributions proportional to $e^4$ and $e^6$. We predict at higher densities a structural transition to oscillating correlations. The thermodynamic functions show a smooth transition from a quadratic root increase to a slower increase like $n_i^{1/4}$ which observes the Onsager bound. Effects of asymmetries in charges and masses are studied with applications to ionic systems with multiple charges and to high-temperature
plasmas, in particular, to
plasmas with He$^{2+}$-ions.
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Statistical Mechanics
Internal-state criticality in Bayesian-inverse-Bayesian inference
Kazuto Sasai and Yukio-Pegio Gunji
We propose
Bayesian-inverse-
Bayesian (BIB) inference in repeated games as a minimal generative model linking
Bayesian inference, statistical mechanics, and heavy-tailed statistics. As a concrete instantiation we simulate repeated $N$-hand cyclic-dominance rock-paper-scissors, a discrete setting in which Nash-targeting
algorithms collapse to uniform random play, so that any non-trivial dynamics must originate internally. Across a multi-axis sweep of design, window, and opponent conditions, the BIB dynamics remain in the same internal critical state, the argmax-persistence distribution staying a heavy-tailed power law with exponent $\alpha\approx 1.43$ at the canonical window. Along the window and alphabet axes the exponent is not constant but drifts toward the universal $3/2$ as the finite-sample residual $(N-1)/(2m)$ vanishes. Bayes-only inference, which lacks the inverse step, shows no analogous universality and no power law. Because the argmax and laminar observables are first-passage reads of one driftless log-posterior walk, what is robust across conditions is the critical, zero-drift state itself, evidenced by the cross-design data collapse rather than by any particular exponent value. The state is also invariant across the hypothesis count $N_h$, with the cutoff time and posterior spread obeying finite-size scaling. Adding an inverse-
Bayesian relaxation step (hypothesis renewal) to ordinary
Bayesian inference is by itself enough to render the dynamics critical, with no external parameter adjustment. Rather than self-organizing toward an absorbing state, BIB reaches criticality by continually reconstructing the hypothesis-space boundary, a mechanism complementary to self-organized criticality that makes the criticality robust across a natural parameter range.
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Materials Science
Halide substitution effects on the photovoltaic properties of Ca$_3$PX$_3$ (X = F, Cl, Br, I) perovskites: advancing solar cell efficiency
P. Dhariwal, D. Prakash, K. D. Verma et al. (+3 more)
Herein, the fundamental physical characteristics like structural, electronic, optical parameters of the Ca$_3$PX$_3$ (X = F, Cl, Br, I) materials have been investigated for their potential optoelectronic applications, particularly for
solar cells and related devices. To the crystallographic investigations, Ca$_3$PI$_3$ has the most stable configuration among all investigated materials. From the band structure analyses of these materials indicate that all materials have a direct bandgap in the range of 2.0 eV to 3.788 eV, which makes them ideal for light absorption. For the photovoltaic applications, we have analysed first-principles spectroscopic screening limited maximum efficiency (SLME) which confirms that the Ca$_3$PI$_3$ material exhibits the highest
solar cell efficiency 29.6% and Ca$_3$PF$_3$ and shows lower efficiency for
solar cell suitability 0.6%. Thus, these results demonstrate the real potential and abilities of halide substitution to tune the materials for particular optoelectronic devices.
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All authors P. Dhariwal, D. Prakash, K. D. Verma, A. Kumari, P. K. Kamlesh, A. S. Verma
Other Condensed Matter · Cross-listed from quant-ph
Transient Information Partition in Coherent Exciton-Phonon-Photon Dynamics
Kunio Ishida
We study transient information partition in a coherent
exciton-
phonon-
photon system using subsystem-resolved
quantum mutual information (QMI). By employing a model with excitonic, phononic, and photonic degrees of freedom, we analyze the dynamics in the $J$-$\nu$ plane, where $J$ characterizes excitonic delocalization and $\nu$ denotes the
exciton-
phonon coupling strength. By comparing time-averaged QMI maps with the absorbed
photon number, we show that optical activity alone does not determine the character of the light-induced transient state. The
exciton-centered information partition identifies a broad crossover between polariton-like and polaron-like transient responses, depending on whether excitonic information is mainly shared with the
photon or
phonon subsystem. In contrast, the
phonon-centered partition reveals a sharper boundary-adjacent redistribution ridge near the boundary between the zero- and one-
exciton ground-state sectors. This ridge is absent from both the ground-state sector map and the
photon-absorption map, indicating that it is neither a static sector boundary nor an enhancement of optical absorption. A variational strength-function analysis connects the ridge to a region-II-like finite-energy polaronic excitation whose dominant spectral weight lies near the one-
phonon energy, and thus the ridge represents a hidden transient correlation structure in which a limited amount of
phonon-related information is preferentially shared with the
photon subsystem before being predominantly allocated to
exciton-
phonon dressing. These results show that QMI-based information partition provides a correlation-based framework for characterizing coherent light-induced transient states in which optical and material degrees of freedom jointly participate
quantum mechanically.
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Statistical Mechanics · Cross-listed from nlin.CG
Effect of rewiring for a sandpile model on a directed network
Alejandro Zamorano and Víctor Muñoz
Several studies have considered sandpile dynamics not over regular grids, but over networks. In this case, avalanches redistribute grains not between neighboring sites in a geometrical sense, but between connected sites, in a topological sense. However, depending on how nodes are connected, grains may never leave the system, preventing energy release. In this work, we study the simplest case, the BTW model in one and two dimensions, rewiring the nodes so that at every rewiring step, the energy release is always possible, and study avalanche statistics as a function of rewiring. In the 1D case, a transition is observed in the Gini coefficient of the load distribution per node at about 85% the number of possible rewirings, a transition which is not evident with other measures, such as the size distribution of avalanches or the mean distance between nodes in the network. In the 2D case, energy release follows a power law even when the grid is fully rewired, while the Gini coefficient, unlike the 1D case, decreases at a steady rate, with a smoother transition. The effect of network size N is studied, finding that there is a transition for the Gini coefficient at the thermodynamic limit N \to \infty for both the 1D and 2D cases, transition which is also observed in the betweenness centrality, but not in other topological measures. Finally, the dependence of the results with the load per rewiring iteration, and the avalanche threshold is studied.
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Disordered Systems and Neural Networks
Boundary-Controlled Liouvillian Relaxation with Exact Steady States Fixed by Dissipative Disorder
Yazhuang Miao, Weizh Ma, Yong Wang et al. (+2 more)
In open
quantum lattice systems, changing the boundary condition would appear to alter both the steady state and the nonzero Liouvillian spectrum. Here we show that boundary conditions can be used to control relaxation without changing the reduced steady state. In a disordered dissipative
quantum link chain, the steady state is determined by an accumulated field defined by link-resolved dissipative disorder, and a gauge-generated transformation built from this field gives exact
symmetry-resolved steady states with nonuniform, accumulated-field-dependent reduced matter occupations. We then construct a reciprocal cyclic boundary condition that preserves these matter occupations while changing the nonzero Liouvillian spectrum. Consequently, open and cyclic chains relax to the same reduced matter steady-occupation profile with different Liouvillian gaps with the cyclic closure accelerating relaxation. In the strong-dissipation limit, this relaxation difference can be reduced to a spectral comparison of effective exclusion processes with open and cyclic boundaries.
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All authors Yazhuang Miao, Weizh Ma, Yong Wang, Xiaolong Zhao, Xuexi Yi
Materials Science
Spin-orbit-enabled Fermi-surface splitting in noncollinear antiferromagnetic SmBi
Long Zhang, Ming Cheng, Jingyu Li et al. (+10 more)
Spin-split electronic structures in compensated antiferromagnets are commonly sought in the nonrelativistic limit, where
magnetic order lifts
spin degeneracy without
spin-orbit coupling (SOC). Whether SOC can instead be the indispensable
symmetry-breaking ingredient remains largely unexplored. Here we combine
quantum oscillations detected by ultrahigh-sensitivity ac magnetostriction,
magnetic-
symmetry analysis and first-principles calculations to resolve the bulk
Fermi-surface
evolution of SmBi across two successive
antiferromagnetic (AFM) transitions. New oscillation branches emerge below TN and undergo a further reconstruction below T*, whereas isostructural SmSb shows no comparable change. For the candidate noncollinear orders of SmBi, breaking global parity-time
symmetry is insufficient in the nonrelativistic limit because residual
spin-space
symmetries protect twofold band degeneracy; conversely, SOC alone cannot lift the degeneracy of the centrosymmetric paramagnetic (PM) phase. Only the coexistence of noncollinear order and SOC locks
spin to the
lattice and removes the residual protection. SmBi therefore realizes a cooperative, relativistic route to
spin-split
Fermi surfaces, broadening unconventional magnetism beyond systems whose splitting is already present in the nonrelativistic limit.
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All authors Long Zhang, Ming Cheng, Jingyu Li, Honghao Wan, Xiaoyuan Zhou, Mingquan He, Aifeng Wang, Yuping Sun, Dong-Hui Xu, Huixia Fu, Youguo Shi, Xuan Luo, Yisheng Chai
Disordered Systems and Neural Networks · Cross-listed from physics.soc-ph
Distance from home matters: Investigation of a basic movement strategy
Mohsen Ghasemi Nezhadhaghighi, Yahya Khalili, Behafarid Hemmatpour et al. (+1 more)
Discovering the fundamental dynamical rules that generate the main statistical features of human mobility is essential for understanding the mechanisms underlying such processes. A prominent example is the exploration and preferential return model and its generalizations, which successfully reproduce several empirical findings. Here, we exploit another observation: the endpoint distances of a trip from the trajectory's starting point are strongly correlated. We consider a movement process in which each user performs a sequence of trips to satisfy a set of demands, given a spatial distribution of suppliers on a two-dimensional
lattice. In each trip, destinations are chosen with a probability that depends on the ratio of the initial and final distances from the user's origin (home). We show that even a single
agent with uniformly distributed demands and suppliers qualitatively reproduces key empirical statistics, such as the power-law distribution of traveled distances. The results are also robust to introducing interactions between
agents via queues and incorporating more realistic demand and supplier distributions.
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All authors Mohsen Ghasemi Nezhadhaghighi, Yahya Khalili, Behafarid Hemmatpour, Abolfazl Ramezanpour
Statistical Mechanics
The Market Crystal: A Spin-Lattice Model for Collective Cryptocurrency States
Hamidreza Oliaei-Moghadam
Collective dynamics in financial
markets can emerge through synchronized movements of large groups of assets. Motivated by analogies with interacting many-body systems, we introduce a
spin-
lattice representation for analyzing collective states in cryptocurrency
markets. In this framework, assets are encoded as binary
spin variables according to the sign of their returns, while correlations between assets determine effective interaction strengths. A correlation-based breadth-first search (CBFS) procedure embeds 169 cryptocurrencies into a $13 \times 13$
lattice, enabling the construction of an Ising-like
Hamiltonian describing the
market configuration, which we call the
Market Crystal. Macroscopic observables such as magnetization and energy provide a statistical-mechanical characterization of collective
market states. The resulting phase-space structure highlights regimes of strong
alignment and fragmentation among assets, with an energy–magnetization pattern suggestive of predominantly
ferromagnetic interactions. This framework offers a statistical-mechanical viewpoint for studying collective behavior in financial systems.
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Materials Science
Sliding ferroelectricity tunable conventional and anomalous spin Hall effects in bilayer 1T'-WTe2
Chao Wu, Pengqiang Dong, Kai Wei et al. (+2 more)
The
spin Hall effect, recognized for its high-speed, low-power, and highly controllable characteristics, is a key enabler for next-generation
memory and logic devices. However, a primary challenge lies in achieving 180$^{\circ}$ magnetization switching without an external
magnetic field in
spin-orbit torque devices. Here, we propose a method to tune the conventional and anomalous
spin Hall effects by the intrinsic sliding ferroelectricity. Importantly, the anomalous
spin Hall effect can enable the field-free switching of perpendicular magnetization. We find a substantial anomalous
spin Hall conductivity of $\sigma_{xy}^{y}$ = 45.62 ($\hbar$/e)S/cm and $\sigma_{yx}^{y}$ = 56.84 ($\hbar$/e)S/cm in monolayer 1T'-WTe$_2$. These values are significantly enhanced to $\sigma_{xy}^{y}$ = -96.77 ($\hbar$/e)S/cm and $\sigma_{yx}^{y}$ = 104.03 ($\hbar$/e)S/cm in the
bilayer 1T'-WTe$_2$. More interestingly, the sliding ferroelectricity enables reversible switching of the signs and magnitudes for both the conventional and anomalous
spin Hall conductivities. This originates from the fact that the sliding ferroelectric markedly shifts the relative
spin Berry
curvature contributions from the valence and conduction bands around the $\Gamma$-X path. Our findings not only reveal a strong coupling between sliding ferroelectricity and
spin transport, but also propose a strategy for the nonvolatile electrical control of spintronic devices.
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All authors Chao Wu, Pengqiang Dong, Kai Wei, Hanbo Sun, Ping Li
Materials Science
Stacking-Directed Polarization and Excitonic Engineering in MoS$_2$/MoSe$_2$ van der Waals Heterostructures
Mohammed El Amine Miloudi and Oliver Kühn
The stacking-dependent polarization and excitonic response of MoS$_2$/MoSe$_2$
heterostructures were investigated using GW+BSE many-body perturbation theory. While homobilayer MoS$_2$ exhibited a switchable interlayer dipole driven by registry-induced
symmetry breaking, the MoS$_2$/MoSe$_2$ hetero-interface remained pinned by the intrinsic chemical potential mismatch between sulfur and selenium. In 2L-MoS$_2$/MoSe$_2$ trilayers, the stacking sequence enabled a deterministic control of photogenerated electrons between the central and bottom MoS$_2$ layers, governed by internal electric fields and quasiparticle band-edge shifts of 60–70~meV. Our calculations predicted a 36~meV interlayer excitonic shift, in remarkable agreement with recent experiments. These results elucidate the microscopic link between atomic registry and many-body interactions, establishing transition metal dichalcogenide trilayers as a potential platform for sliding ferroelectricity and programmable optoelectronic functionalities.
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Soft Condensed Matter
Generation of two-dimensional pulses in lipid monolayers by rapid photoswitching
Tom Rosenstein, Philipp Zolthoff, Jan Kierfeld et al. (+1 more)
We study pressure pulse generation and propagation in lipid monolayers by an experimental approach employing rapid photoisomerization of photoswitchable lipids (azoPC). This allows us to generate longitudinal surface pressure pulses by optical flash excitation in both free and constrained layer geometries. We compare the observed pulse shapes with a theoretical approach based on a nonlinear fractional wave equation for a surface displacement field, where a fractional time derivative term captures the hydrodynamics of the monolayer subphase. We explore channel geometries of different lengths and widths and find quantitative agreement between theory and experiment regarding pulse speed and pulse shapes. For narrow channels, we employ a one-dimensional version of the fractional wave equation to study pulse propagation without any fit parameters by using the pressure signal at a close pressure sensor as boundary condition to predict the pressure signal at a second far sensor. A full two-dimensional description can capture all effects arising from the channel geometry for wider channels using one common set of fit parameters for the pulse excitation that can be applied to all geometries. The nonlinearity in the fractional wave equation plays no role in explaining the observed pulse shapes because pulse amplitudes generated by azoPC photoswitching remain very small.
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All authors Tom Rosenstein, Philipp Zolthoff, Jan Kierfeld, Matthias F. Schneider
Strongly Correlated Electrons
Magneto-ionic control of topological transport in SrRuO3 via band topology engineering
Xuanchi Zhou, Xiaohui Yao, Xiaomei Qiao et al. (+5 more)
The interplay between
spin-orbit coupling (SOC) and nontrivial band
topology in ferromagnets gives rise to a rich landscape of topological transport phenomena such as anomalous
Hall effect (AHE) and topological
Hall effect (THE). One central goal in modern spintronics lies in the realization of the active control over topological transport phenomena in a reversible fashion, while unambiguously disentangling respective contributions of THE and AHE to the net
Hall effect remains a formidable challenge. Here we establish magneto ionic control as a powerful paradigm for dynamically engineering topological transports in a 4d-orbital SrRuO3 system with sizable SOC and itinerant ferromagnetism. Harnessing controllable protonation or oxygen vacancy incorporation, the
Fermi-level upshift relative to avoided band crossings are realized through band filling control, giving rise to tunable reversal temperature of AHE polarity. Of particular note is the emergence of hump like
Hall anomalies through extensive ionic doping that can be reversibly switched, irrespective of AHE polarity, providing evidence for a THE signal driven by broken inversion
symmetry rather than a two channel AHE. Our findings provide a viable tuning knob for Berry
curvature engineering, enabling on demand control of topological transports in strong SOC ferromagnets for low power, reconfigurable all
oxide spintronic devices.
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All authors Xuanchi Zhou, Xiaohui Yao, Xiaomei Qiao, Guowei Zhou, Wenjing Huo, Shuang Li, Huihui Ji, Xiaohong Xu
Materials Science · Cross-listed from physics.chem-ph
The impedance of a charged flat-plate electric double-layer capacitor
Adrian L. Usler, David Fertig and Mathijs Janssen
We calculate the impedance of a flat-plate electric double-layer (EDL) capacitor by means of Finite Element Method simulations of modified Poisson–Nernst–Planck equations. In Nyquist representation, the impedance spectra show a slanted line at intermediate frequencies if the capacitor is biased by a voltage, $U_\mathrm{bias}\neq 0$, or if the cation and anion
diffusion coefficients differ, $D_-\neq D_+$. By inspecting the concentration perturbations in the relevant frequency range, we confirm that the slanted line is in both cases related to ambipolar salt
diffusion. On the basis of our impedance data, we disprove two previously made claims: 1) that the width $R_\mathrm{sl}$ of the slanted-line region represents an EDL resistance; and 2) that the slope $k_\mathrm{sl}$ of the slanted line is a measure of the ratio of the
diffusion and charging time scales, $\tau_\mathrm{diff}/\tau_\mathrm{c}$. For the quantitative analysis of flat-electrode EDL capacitor impedance, we propose instead two equivalent
circuits, for the cases $D_-\neq D_+$ and $U_\mathrm{bias}\neq 0$. These two cases give rise to antisymmetric and symmetric salt perturbations, which are best described by a Warburg short and Warburg open element, respectively. From our
circuit analysis, we obtain quantitative relations that link the Warburg prefactors to the ambipolar
diffusion coefficient, the chemical capacitance of the bulk electrolyte, and the differential charge efficiency of the EDLs. We thus provide a theoretical framework that explains why the width of the slanted line saturates at large biases, why it vanishes for large ion packing fractions, and how the system's overall capacitance is limited by the finite amount of ions in a closed system.
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Statistical Mechanics
Nonlocal fractional Kardar-Parisi-Zhang dynamics of grain boundaries
Kai Zhao
The kinetic roughening of driven grain boundaries (GBs) is fundamentally mediated by the collective behavior of disconnections, whose long-range $1/r$ elastic interactions distinguish them from conventional growing surfaces. Through large-scale molecular dynamics simulations and a nonlocal fractional Kardar-Parisi-Zhang (fKPZ) theory, we demonstrate that driven GBs undergo a sharp transition of morphology at the yield point, from the quenched Edwards-Wilkinson universality class ($H \approx 0.33$) to an anomalous fKPZ regime ($H \approx 0.8$), while the 1/r nonlocal elasticity manifests as the fractional relaxation of GB morphology. The results show that the avalanche noise arrests the gradient catastrophe induced by the KPZ nonlinearity. Governed by the nonlocal elastic kernels, the resulting morphology breaks the Gaussian self-affinity and parallels the universality class of dynamic fracture.
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Materials Science · Cross-listed from physics.app-ph
Revisiting Theoretical Modeling of Seebeck Coefficient of Semiconductors
Yuchao Hua
We revisit the closed-form models of Seebeck coefficient, and identify the thermodynamic flaws in those extensively-used methodologies, essentially including the confusion of electrochemical potential and electrical potential within the definition, arbitrarily neglecting the dependence on conduction band bottom and
Fermi level when calculating distribution function spatial gradient, and the improper heat flux presentation. Here, an alternative methodology is presented, which derives the Seebeck coefficient model based on the drift-
diffusion equation with the Soret effect in the open
circuit condition. The reversible model that eliminates the electron velocity and relaxation terms in the formulation is recovered for the band term in the near-
equilibrium case, and it can give the lower bound of Seebeck coefficient in theory, while the
phonon-drag term is of the identical form to the Boltzmann transport equation(BTE)-based one. A case study is performed for highly-n-doped Silicon, where the reversible, ballistic(based on Landauer formulation) and BTE models are compared with each other and with the experimental data. The reversible model gives the fairly-good predictions for the experiments. Given its theoretical-soundness, simple form and low computation cost, the reversible model can serve as a concise alternative for evaluating thermoelectric properties in both the reversible and near-
equilibrium cases.
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Strongly Correlated Electrons
Spectroscopic fingerprints of a ferroaxial charge density wave
Jiangchang Zheng, Zhongyi Zhang, Fazhi Yang et al. (+11 more)
Unconventional charge density waves (CDWs) with complex order parameters can host exotic collective modes and non-trivial
topologies. They have emerged as a new frontier in the study of
quantum matter. Recent experiments on rare-earth tritellurides have reported evidence for a ferroaxial CDW through the detection of characteristic Raman modes. This phase, often regarded as a hidden order, has been recognized to arise from the coupling between charge and orbital degrees of freedom in these materials. Yet, spectroscopic insight into its underlying electronic structure and the explicit form of its order parameter
symmetry has remained elusive. Here, we present results from linearly polarized angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) measurements of the CDW phase in LaTe$_3$. Our ARPES measurements reveal a complex landscape of spectral gaps across the reconstructed
Fermi surface, while our STM-based quasiparticle interference (QPI) mapping, enhanced through the selective deposition of atomic scattering centers, directly reveals an inter-orbital CDW with mixed $p_x$-$p_z$ orbital character. The detailed analysis of the QPI characteristics in terms of the order parameter
symmetry within the orbital subspace of the
Fermi surface suggests a mixed CDW phase with substantial ferroaxial component, which breaks all vertical mirror
symmetries. More broadly, our work establishes a powerful spectroscopic pathway, based on scattering off individual atoms, for identifying and characterizing hidden, multi-component electronic orders in
quantum materials using STM and ARPES measurements.
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All authors Jiangchang Zheng, Zhongyi Zhang, Fazhi Yang, Josh Leeman, Luanjing Li, Zihan Lin, Zijian Fei, Tianhao Guo, Siyu Heng, Xin Liang, Leslie M. Schoop, Junzhang Ma, Hoi Chun Po, Berthold Jäck
Mesoscale and Nanoscale Physics
Shu-Hui Zhang, Shu-Qi Liu, Dan-Yang Han et al. (+4 more)
Antiferromagnets (AFMs) are promising for high-density spintronics due to their zero net magnetization, yet conventional AFM spintronics relies on
spin splitting-a requirement that excludes many collinear AFMs with compensated
spin sublattices. Here we exploit the sublattice degree of freedom in a honeycomb AFM with zero
spin splitting. We uncover a coupling between
spin and sublattice: the out-of-plane pseudospin polarization is
spin-dependent, a mechanism we term partial pseudospin-
spin coupling. This allows switching of the pseudospin polarization by reversing the Néel vector. Introducing an
impurity into a specific sublattice induces Friedel oscillations with a sublattice-resolved amplitude ratio dictated solely by the pseudospin polarization, which is directly measurable by
spin-polarized scanning tunneling microscopy. Furthermore, we demonstrate Néel-vector-controlled transmission and a large nonvolatile tunneling magnetoresistance in an all-in-one AFM junction, with pronounced resonant enhancement in gate-tunable two-dimensional devices. Our work establishes a new paradigm-AFM pseudospintronics-that utilizes the sublattice pseudospin in zero-
spin-splitting AFMs, extending spintronics beyond the conventional
spin-splitting paradigm.
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All authors Shu-Hui Zhang, Shu-Qi Liu, Dan-Yang Han, Zhan Kong, Ding-Fu Shao, Wen Yang, Kai Chang
Quantum Gases · Cross-listed from quant-ph
Prethermal cooling with many-body quantum quenches
Jacob F. Steiner, Mohammad Hafezi, Stefan Kehrein et al. (+1 more)
Many-body
quantum quenches are typically associated with heating. In this work, we show that
quantum quenches that perform positive work on the system can still lead to effective cooling of low-energy degrees of freedom if the quench energy is deposited in long-lived high-energy excitations. We discuss this explicitly for a quench of the hopping term t in the strong-coupling (U >> t) fermionic Hubbard model at half filling, where the quench induces a very long-lived non-
equilibrium doublon density. The associated prethermal state persists for a time exponentially large in (U/t)^2. During this time window, we find an effective prethermal temperature that is reduced by the square of the ratio of final to initial hopping amplitude with respect to the initial temperature. This manifests as an effective fluctuation-dissipation relation that holds for doublon-number conserving operators. In a practical implementation the Hubbard system acts as a refrigerant to cool a target system provided the coupling conserves doublon number. Our protocol can be thought of as a
quantum quench many-body generalization of adiabatic demagnetization.
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All authors Jacob F. Steiner, Mohammad Hafezi, Stefan Kehrein, Gil Refael
Soft Condensed Matter
Saturation Coverage in Binary Mixtures of Oriented Regular Polygons via Random Sequential Adsorption
Aref Abbasi Moud
We study saturation in two-dimensional binary mixtures of fixed-orientation regular polygons deposited by random sequential adsorption (RSA). Polygons with (n\in{3,\dots,23}) are considered under an equal-area constraint, isolating shape effects from size effects. Saturated configurations are generated using an adaptive split-voxel RSA
algorithm with exact overlap detection based on the Separating Axis
Theorem, allowing a systematic exploration of all distinct binary shape combinations. Jamming coverage depends strongly on polygon geometry despite identical particle area. Triangle-containing mixtures yield the lowest coverages, whereas axis-aligned squares achieve the maximum observed value, (\phi_sat\approx0.5646). Even-sided polygons consistently outperform neighboring odd-sided polygons, revealing a parity effect associated with centrosymmetry. For odd (n), the pure-species saturation approaches the disk RSA limit (\phi_disk\approx0.547) from below according to (\phi_sat(n)=\phi_disk-c/n^\alpha), with (\alpha\approx2.41\pm0.06), close to the (1/n^2) scaling expected from isoperimetric arguments. Even-sided polygons instead converge from above, indicating a
symmetry-driven packing advantage that disappears only in the circular limit. These trends are explained through the excluded area (E_{AB}=\mathrm{Area}(P_A\oplus(-P_B))), computed analytically via Minkowski sums. Centrosymmetry fixes (E_{AA}=4A_0) for even (n), whereas odd polygons have a larger excluded area that decreases monotonically toward the same limit as (n\to\infty). Saturation coverage is negatively correlated with excluded area, consistent with a mean-field RSA description and directly linking
geometric symmetry to jamming efficiency.
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