Strongly Correlated Electrons
Thermal Hall Resistivity as a Unifying Description of Phonon Thermal Hall Effect in Various Insulators
Dirui Wu, Ying Kit Tsui, Xavier Loh et al. (+8 more)
A considerable
phonon thermal
Hall effect was recently discovered across a diverse collection of materials. To clarify this enigmatic thermal
Hall response in various
insulators, we investigate the doped Mott
insulator La$_{5/3}$Sr$_{1/3}$NiO$_4$ as an example material system and reveal a characteristic
phonon-dominated thermal
Hall effect. As a sensitive probe of the transverse thermal response, the thermal
Hall resistivity $w_{xy}$ exhibits an insulating-like temperature dependence $w_{xy}(T)$, a linear
magnetic-field dependence $w_{xy}(H)$ near $H=0$, and a $T$-linear thermal
Hall angle at low temperatures. The presence of similar phenomena across a series of
insulators suggests that $w_{xy}$ serves as a unifying description of
phonon thermal
Hall effect, corroborated by an apparent correlation between the insulating-like $w_{xy}(T)$ and material's localized electronic state.
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All authors Dirui Wu, Ying Kit Tsui, Xavier Loh, Minseong Lee, Eun Sang Choi, Takao Sasagawa, Toshimitsu Ito, Xiao Renshaw Wang, Pinaki Sengupta, Xinyang Zhang, Christos Panagopoulos
Materials Science · Cross-listed from physics.comp-ph
Matrix-free phase-field modeling of fracture in micromechanical testing simulations of inelastic materials
Fabio Di Gioacchino, Rezgar Shakeri, Zachary Atkins et al. (+4 more)
Resolving steep damage gradients across diffuse cracks in the phase-field modeling of fracture favors the use of high-order finite elements, for which
matrix-free methods can provide superior performance and scalability. Here, we implement the Peric & Dettmer constitutive framework for visco-elastoplastic materials in an open source solid mechanics library supporting
matrix-free operators for high-order finite elements with p-multigrid preconditioning on GPUs. We introduce a rheological fracture element assembled in series with the Peric & Dettmer block, keeping fracture and inelastic material properties mutually independent. We conduct numerical simulations of tensile and compressive quasistatic tests on synthetic particle-
matrix microstructures using an El Capitan high-performance computing prototype. The results reproduce representative inelastic responses and fracture patterns, including X-shaped cracking observed in
polymer-bonded explosives and cup-and-cone fracture in ductile metals.
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All authors Fabio Di Gioacchino, Rezgar Shakeri, Zachary Atkins, Karen Stengel, Layla Ghaffari, Jeremy Thompson, Jed Brown
Mesoscale and Nanoscale Physics
Exceptional-Point Geometry of Weak Topological Boundary States
Rafael A. Molina, Kevin González and Pedro A. Orellana
In this article, we demonstrate that weak
topology can be formulated geometrically in terms of exceptional singularities of an analytically continued Bloch
Hamiltonian. A general plaquette
chiral model in two dimensions serves as a minimal realization of dual weak
topology, possessing two independent families of weak topological invariants, one for each spatial direction. The weak-topological edge states correspond to exceptional points in complex momentum space, while corner zero modes emerge from exceptional curves obtained by complexifying both momenta. Compact localized states arise when the exceptional roots collapse to the origin. This framework provides a unified complex-momentum description of edge, corner, and compact localization.
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Superconductivity
Magnetically memorable inductance in superconducting multilayer resonators
R. Tyumenev, D. S. Kalashnikov, B. V. Fradkin et al. (+10 more)
Superconductor-ferromagnet hybrid structures with tunable kinetic inductance are promising elements for neuromorphic and
quantum computing
circuits. We report the fabrication and microwave characterization of split-ring resonators based on Nb/Co/Nb/Co/Nb/Al
spin-trigger multilayers and demonstrate a non-volatile
spin-valve effect on their resonant properties. Reversal of the relative magnetization orientation of the cobalt layers produces a reproducible shift of the resonant frequency up to 4 MHz at zero applied
magnetic field, corresponding to a change in the kinetic inductance of the structure. The incorporation of a proximitized aluminum overlayer is shown to enhance the inductance contrast between the parallel and antiparallel
magnetic states by a factor of approximately three relative to structures without this layer. The experimental results are in quantitative agreement with a microscopic model based on the Usadel equations. The demonstrated
magnetic memory of the resonant frequency at zero field establishes
spin-trigger multilayers as viable field-programmable inductive elements for superconducting digital and neuromorphic
circuits.
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All authors R. Tyumenev, D. S. Kalashnikov, B. V. Fradkin, A. A. Neilo, A. G. Shishkin, N. V. Klenov, I. I. Soloviev, A. A. Golubov, M. Yu. Kupriyanov, I. A. Golovchanskiy, V. S. Stolyarov, A. S. Sidorenko, S. V. Bakurskiy
Mesoscale and Nanoscale Physics
End-State-Controlled Quantum Transport in Armchair Graphene Nanoribbon Artificial Quantum Materials
David M T Kuo
Artificial
quantum materials based on atomically precise
graphene nanostructures provide an ideal platform for exploring
quantum phenomena arising from localized electronic states. Here, we develop a real-space theoretical framework to elucidate the microscopic origin of interface states in
graphene architectures composed of $n$-triangulenes and armchair
graphene nanoribbons (AGNRs). By continuously tuning the coupling between
graphene building blocks, we reveal the
evolution of triangulene zero-energy modes and AGNR end states into compact localized node orbitals at three-arm junctions. For the
chiral bipartite junctions considered here, the number and sublattice character of these node orbitals follow a general counting relation, $N_{node,\delta}=|N_{es,t,A(B)}-N_{tri,0,B(A)}|$, where $N_{es,t}$ is the total number of AGNR end states contributed by the three AGNR arms and $N_{tri,0}$ is the number of triangulene zero-energy modes. The resulting node-orbital chirality is determined by the dominant constituent: when $N_{es,t}>N_{tri,0}$, they inherit the sublattice chirality of the AGNR end states ($\delta=A(B)$), whereas for $N_{tri,0}>N_{es,t}$ they inherit that of the triangulene zero-energy modes ($\delta=B(A)$). Using experimentally synthesized triangulene nanographenes as representative examples, we further identify their low-energy zero-mode structure and investigate its manifestation in tunneling transport within an extended Anderson framework. Finally, we demonstrate that these node orbitals can serve as elementary building blocks for constructing artificial
graphene nanoribbons with highly tunable flat subbands near the
Fermi energy. The resulting compact localized states exhibit controllable degeneracy and strongly anisotropic
quantum transport.
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Soft Condensed Matter
Helical stability of double-stranded semiflexible chains with interstrand interactions
Farisan Dary, Donn Liew, Haiyi Liang et al. (+1 more)
The mechanical and structural properties of dsDNA have been successfully described by models with varying levels of complexity and coarse-graining schemes. Prior work has characterized local stacking/twist effects and force-torque phase diagrams under external constraints. However, the role of base-pairing and torsional elasticity in global morphological transitions remain poorly characterized in the absence of external constraints. Here we investigate the delicate balance required for the strength of base-pairing interactions and the twisting energy to preserve the double-helix structure in a model made up of two semiflexible chains. We found that the model exhibits several distinct morphological phases: flat, random coil, double-helix, and the unwound double-helix. We calculate the Gauss linking number to characterize transitions between these phases.
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All authors Farisan Dary, Donn Liew, Haiyi Liang, Ee Hou Yong
Materials Science · Cross-listed from physics.optics
Phase singularity enabled polarization switchable analog spatial differentiation in an atomic MoS$_2$ planar Fabry-Pérot cavity
Zhonglin Li, Yingying Wang, Jiawei Kang et al. (+3 more)
Reconfigurable analog optical computing requires rapid and efficient switching between core mathematical operations, such as first- and second-order spatial differentiation. Here, we demonstrate a monolayer MoS$_2$ integrated a planar Fabry-Pérot (F-P) cavity that performs polarization switchable analog spatial differentiation under oblique incidence. By exploiting polarization dependent phase singularities, the device satisfies distinct optical transfer functions for different-order differentiation at the same operating condition. As a result, first-order and second-order derivatives of input images are experimentally realized by simply switching the incident polarization. These results establish the planar cavity as a compact reconfigurable spatial differentiator, whose computational order is controlled solely by light polarization. This approach provides a fast, convenient, and integration friendly strategy for tunable optical computing, and enables polarization switchable edge detection for image processing, with potential applications in real-time object recognition, feature extraction, and optical data compression.
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All authors Zhonglin Li, Yingying Wang, Jiawei Kang, Yangyang Zhang, Wenjun Liu, Zexiang Shen
Materials Science · Cross-listed from quant-ph
Picosecond-resolved entanglement distribution over an urban free-space channel
Alessandro Laneve, Fabrizio Cienzo, Santiago Gomez et al. (+18 more)
Time-evolving entangled states describe
quantum particles whose correlations evolve in time according to a well-defined dynamics. Such states can be generated in a variety of physical systems and are promising resources for several
quantum technologies, ranging from
quantum clock synchronization to
quantum communication. However, their full potential is currently limited by the fact that the
entanglement dynamics often occur on timescales comparable to the achievable synchronization precision, especially in experiments aimed at distributing
entanglement through noisy urban channels. In this context, accurate timing is not merely a technical detail, but a fundamental requirement for faithfully observing and exploiting the underlying
quantum correlations. Here, we demonstrate the faithful distribution of a fast-evolving entangled state over a 270 m free-space channel connecting two buildings in the center of Rome. The developed system incorporates a synchronization device capable of achieving sub-50 ps timing accuracy between the two ends of the link while simultaneously supporting channel stabilization. Our results demonstrate that time-evolving
entanglement can be reliably transmitted through a noisy urban free-space channel, representing an important
benchmark toward long-distance free-space
quantum communication and the future implementation of time-correlated entangled states in demanding scenarios such as satellite-based
quantum networks.
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All authors Alessandro Laneve, Fabrizio Cienzo, Santiago Gomez, Paolo Barigelli, Philip Menz, Mattia Beccaceci, Giuseppe Ronco, Giorgia Grossi, Ievgen Brytavskyi, Thomas Oberleitner, Markus Wiener, Christian Weidinger, Tobias M. Krieger, Ailton Garcia Jr., Saimon Filipe Covre da Silva, Michele B. Rota, Nicolò Spagnolo, Henning Weier, Fabio Sciarrino, Armando Rastelli, Rinaldo Trotta
Materials Science
Tunnel magnetoresistance effect with a Cr-doped $\mathrm{RuO_{2}}(110)$ altermagnet
Katsuhiro Tanaka, Takuya Nomoto and Ryotaro Arita
Antiferromagnets can have a finite
spin-polarization in the momentum space when their
magnetic structure breaks the macroscopic time-reversal
symmetry. This
spin-polarization can produce a
spin-polarized electric current even in antiferromagnets with vanishingly small net magnetizaton, which supports the antiferromagentic tunnel magnetoresistance (TMR) effect. In this paper, using first-principles calculations, we study the TMR effect with a doped altermagnet $\mathrm{Ru}_{1-x}\mathrm{Cr}_{x}\mathrm{O}_{2}$ with $(110)$ orientation, whose collinear
antiferromagnetic structure breaks the time-reversal
symmetry macroscopically. The momentum-dependent
spin-polarization combined with the $(110)$
crystal orientation makes the electric current
spin-polarized through bulk $\mathrm{Ru}_{1-x}\mathrm{Cr}_{x}\mathrm{O}_{2}(110)$. We further calculate the TMR effect in the $\mathrm{Ru}_{1-x}\mathrm{Cr}_{x}\mathrm{O}_{2}(110)/\mathrm{TiO_{2}}(110)/\mathrm{Ru}_{1-x}\mathrm{Cr}_{x}\mathrm{O}_{2}(110)$ tunnel junction and show that a finite TMR effect emerges. Based on the analysis of the tunneling transport, the TMR effect is attributed to the
spin polarized tunneling transport with momentum dependence and the interfacial
magnetic structures, as well as the
spin-polarized electric current in a bulk form of $\mathrm{Ru}_{1-x}\mathrm{Cr}_{x}\mathrm{O}_{2}(110)$.
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Materials Science
Complete Raman Tensor Determination in Birefringent $\beta$-Ga$_2$O$_3$ by Single-Stage Hyperspectral Analysis of Polarization Angle-Resolved Raman Spectra
Hans Tornatzky, Jonas Rose, Moritz Meißner et al. (+5 more)
The low
symmetry of the monoclinic phase of Ga$_2$O$_3$ leads to pronounced optical anisotropy and, consequently, to birefringence, which strongly affects the Raman response. Because Raman scattering is fundamentally sensitive to the polarizability of a material, this anisotropy must be carefully accounted for in order to extract quantitative information - an effort that has only recently been shown to be feasible in such media. Here, we report Raman measurements from all three principal
crystal planes $(100)$, $(010)$, and $(001)$, as well as from the $(\overline{2}01)$-plane of a $\beta$-Ga$_2$O$_3$ single
crystal. By combining polarization angle-resolved Raman spectroscopy (PARRS) with a newly developed fitting procedure and explicitly accounting for birefringence, we achieve full spectral separation and quantitatively determine the energies and relative Raman tensor elements of all 15 Raman-active modes.
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All authors Hans Tornatzky, Jonas Rose, Moritz Meißner, Benjamin M. Janzen, Zbigniew Galazka, Juan Sebastián Reparaz, Manfred E. Ramsteiner, Markus R. Wagner
Statistical Mechanics · Cross-listed from hep-th
Flavour current correlators and the non-Abelian hydrodynamic approximation: the charged sector
Thomas Apostolidis, Matti Järvinen, Elias Kiritsis et al. (+3 more)
Flavor-current correlators are studied in strongly-coupled dense (
holographic) matter, at finite
quark chemical potential $\mu_q$ and finite isospin asymmetry. The non-Abelian hydrodynamic description of the charged currents is derived in the presence of an isospin chemical potential $\mu_3$. The two-point correlators of charged currents are then computed holographically at finite
quark and isospin chemical potentials. In the near-extremal hydrodynamic regime, $\omega, k, T, \mu_3 \ll \mu \equiv \sqrt{\mu_q^2+\mu_3^2}$, relevant for cold strongly coupled matter, the IR properties of the correlators are studied. It is shown that in this regime, the correlators agree with the non-Abelian hydrodynamic predictions. Therefore, the traditional regime of validity of standard hydrodynamics extends beyond $\omega, k \ll T \ll \mu$ to the so-called extended hydrodynamic regime $T\ll \omega, k \ll \mu$. The
holographic product formula is applied to the present non-Abelian system, and is used to propose an extended hydrodynamic approximation capturing both hydrodynamic-like poles and the leading effect of AdS$_2$ poles, by resumming the low-$\omega$ logarithms. The results are verified through a detailed numerical analysis of the exact correlators and quasi-normal mode spectrum.
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All authors Thomas Apostolidis, Matti Järvinen, Elias Kiritsis, Francesco Nitti, Andrea Olzi, Edwan Préau
Superconductivity
Evidence for fully-gapped superconductivity in BCS superconductor NiBi3
Atul Gangwar, Kunal Yadav, S.Patnaik et al. (+1 more)
We investigate the physical characteristics, normal state and superconducting properties of NiBi3 single
crystals. Measurements of electrical resistivity, magnetization, and London penetration depth demonstrate a superconducting transition temperature, Tc=4.0 K, with a sharp transition in resistivity (Tc = 0.20 K) and RRR = 18, reflecting the high quality of NiBi3 single
crystals. With both orientations H perpendicular b and H parallel b of NiBi3 single
crystals, we estimated the upper critical field, Hc2, from the magnetization data. In both orientations, Hc2 is significantly smaller than the Pauli limit, suggesting the orbital pair breaking in superconducting state. The coherence length, xi(0) = 26.78 nm, electron-
phonon coupling constant, lambda(e-p) = 0.81, and penetration depth, lambda0 = 181.8 nm, suggest type-II superconductivity in NiBi3. In the superconducting state, lambda(T) is best described by an s-wave BCS model and does not have linear or quadratic dependency with T, which is in line with the expectation for a node-less superconducting order parameter. The temperature
evolution of the superfluid density, obtained from lambda(T), reveals a fully gapped superconductivity in NiBi3, with a superconducting gap = 4.07. All the results from the present study indicate that NiBi3 is a typical type-II, BCS-like, moderately strong coupled, and fully gapped
superconductor in the dirty limit.
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All authors Atul Gangwar, Kunal Yadav, S.Patnaik, Sandip Chatterjee
Materials Science · Cross-listed from physics.optics
Monolithic Magneto-Optical Mach-Zehnder Isolator Using Laser-Annealed Iron Garnet on a Silicon Waveguide
Tomoya Sugita, Reona Motoji, Yuki Yoshihara et al. (+5 more)
Stable silicon photonic
circuits require monolithically integrated optical isolators based on magneto-optical garnet. However, crystallizing the garnet by conventional furnace annealing exposes the entire chip to high temperature and degrades the silicon waveguides and the metal electrodes. Here we avoid this degradation by using local
laser annealing in
vacuum to crystallize cerium-substituted yttrium iron garnet (Ce:YIG), deposited by ion beam sputtering without a seed layer, directly within a silicon-based Mach-Zehnder interferometer. A 915 nm beam heats only the garnet region confined in micrometer-scale trenches, leaving the surrounding
circuit and electrodes intact. The device achieves an isolation ratio of 13.6 dB at a wavelength of 1540 nm, corresponding to a Faraday rotation of 0.092$\deg$/$\mu$m, with an insertion loss of 20.4 dB and a propagation loss of 9.5 dB. Transmission electron microscopy reveals the crystallized Ce:YIG and a ~10 nm boundary region at the interface with the Si waveguide. These results demonstrate that thermally sensitive silicon photonic devices and magneto-optical thin films requiring high-temperature processing can be integrated by a high-throughput technique compatible with mass production.
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All authors Tomoya Sugita, Reona Motoji, Yuki Yoshihara, Dan Maeda, Hiroki Yamamoto, Hibiki Miyashita, Kazushi Ishiyama, Taichi Goto
Statistical Mechanics · Cross-listed from quant-ph
Large deviations in quantum dynamics and complexity
Xiangyu Cao and Jorge Kurchan
We study three definitions of large deviation in many-body
quantum dynamics: (i) via the full distribution of an extensive observable, (ii) via the distribution of measurement outcomes (from a continuous monitoring of the observable) over a time interval $t \le t_{\max}$, and (iii) via the distribution of expectation values over $t \le t_{\max}$. In generic systems without conservation laws, the large deviation function (i) reaches its longtime limit at $t \sim \mathcal{O}(1)$, independently of system size $N$. (ii) and (iii) reach their longtime limit at $t \sim e^{ N}$ and $t \sim \exp(e^{N})$, respectively. Before that, there is a sharp frontier between the explored and unexplored outcomes/expectation values; their distribution equals the longtime limit truncated at values that drift with $t_{\max}$. We propose that the
evolution of these values with $t_{\max}$ provides a measure of
quantum complexity.
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Strongly Correlated Electrons
Gaplessness indicator by topologically trivial twisting operators
Yuan Yao, Linhao Li and Feng-Feng Song
We propose several general necessary conditions for
quantum many-body system in one dimension respecting U(1)
symmetry to be gapped. We show that the ground-state expectation value of topologically trivial twisting operators must approach unity in the thermodynamic limit with a certain finite-size scaling. Equivalently, its violation can indicate gaplessness of U(1)-symmetric
Hamiltonians. The topological triviality of such a twisting operator enables us to derive infinitely many other gaplessness indicators by static structure factor to any order in real experiments, which are impossible to obtain by earlier topologically nontrivial twisting operators. We also apply analytic and numerical calculations to test the efficiency and consistency of our results.
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Strongly Correlated Electrons · Cross-listed from nucl-th
Gauge Auxiliary-Field Quantum Monte Carlo Method for Many-Fermion Systems
Zhaozhan Zhang
We propose novel
Quantum Monte Carlo (QMC) methods for interacting many-
fermion systems by leveraging the
stochastic gauge freedom, originally developed in Gaussian phase-space QMC, within the phaseless auxiliary-field QMC (AFQMC) framework. In particular, we reinterpret the conventional force bias in phaseless AFQMC as a drift gauge and explore
Fermi gauges based on natural orbitals of a reduced one-body density
matrix defined via a mixed
estimator, yielding
stochastic, time-dependent Hartree-Fock-like dynamics. We propose a
symmetry-projection sampling scheme to enhance the sampling efficiency. As a proof of concept, we apply these gauge-augmented AFQMC methods to a simple shell-model
Hamiltonian: the Lipkin-Meshkov-Glick model. Numerical results illustrate the potential of
stochastic gauges to enhance accuracy and reduce fluctuations, underscoring the promise for advancing these new techniques toward more realistic shell-model applications.
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Materials Science
Uni-XAS: Alignment-Driven Bidirectional Multimodal Learning for X-ray Absorption Spectroscopy
Suyang Zhong, Yuhao Zhao, Boying Huang et al. (+6 more)
X-ray absorption spectroscopy (XAS) is a key technique for probing local atomic environments, yet learning based modeling must bridge two heterogeneous modalities: 1D continuous spectra and 3D atomic structures. Existing approaches typically decouple forward spectrum prediction and inverse structure inference into separate regression tasks, hindering shared representation learning. Moreover, severe permutation ambiguity among identical atoms often limits inverse modeling to coarse structure descriptors rather than explicit 3D structure generation. In this work, we present Uni-XAS, a unified
benchmark and learning framework that reframes bidirectional XAS modeling as a cross-modal
alignment and conditional generation problem. We first propose XASLip, an
alignment recipe coupling a physics-aware spectral encoder with an absorberaware
manifold optimization strategy to resolve fine-grained intra-element coordination variations. Building upon this shared latent space, we formulate forward prediction as anchored absolute-spectrum generation via
retrieval-augmented decoding, effectively preventing physical scale collapse and energy drift. For the inherently ill-posed inverse problem, we introduce Permutation-Rectified Flow Matching, which integrates type-wise optimal transport into a continuous generative flow to provide a principled solution to ligand permutation ambiguity without relying on heavy high-order equivariant architectures. Evaluated on a largescale standardized
benchmark of 328,839 structure-spectrum pairs, Uni-XAS demonstrates strong performance in cross-modal
retrieval, accurate absolute-spectrum prediction, and composition-conditional 3D structure generation, establishing a scalable, reproducible, and protocol-consistent foundation for
multimodal learning and standardized evaluation in scientific spectroscopy.
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All authors Suyang Zhong, Yuhao Zhao, Boying Huang, Fanjie Xu, Pengwei Xu, Haoyi Tao, Xi Fang, Jun Cheng, Fujie Tang
Materials Science
Visualizing Microwave-Driven Dynamics of Antiskyrmions and Surface Skyrmions
Zhuolin Li, Daisuke Nakamura, Spencer Reisbick et al. (+9 more)
Microwaves provide coherent access to low-energy excitations and serve as effective probes of high-frequency
spin dynamics in
quantum and
magnetic systems. For topological
spin textures, microwave excitation is expected to generate rich collective responses, yet direct real-space observation of ultrafast dynamics remains limited. Here we use time-resolved Lorentz transmission electron microscopy to visualize microwave-driven dynamics in a hybrid antiskyrmion structure composed of a central antiskyrmion and surface skyrmions. We resolve the picosecond
evolution of antiskyrmion area and second-harmonic signals, evidencing nonlinear responses of
spin textures under microwave excitations. We track the core motions of the antiskyrmion and surface skyrmions, which follow distinct trajectories while sharing the same rotational sense. Micromagnetic simulations reproduce the key observations and associate the dynamic modes with the spatial modulation of the core profile along the thickness. These achievements establish ultrafast electron microscopy as a powerful real-space approach for probing high-frequency microwave-driven dynamics of topological
magnetic solitons.
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All authors Zhuolin Li, Daisuke Nakamura, Spencer Reisbick, Chuhang Liu, Myung-Geun Han, Kosuke Karube, Wataru Koshibae, Naoto Nagaosa, Yasujiro Taguchi, Yimei Zhu, Yoshinori Tokura, Xiuzhen Yu
Statistical Mechanics · Cross-listed from hep-th
Quantum Mpemba effect in holography
Xian-Hui Ge, Shuta Ishigaki, Yu-Qi Lei et al. (+1 more)
We investigate the
quantum Mpemba effect in a
holographic superfluid, in which states with stronger initial
symmetry breaking relax faster toward the
symmetry-restored
equilibrium. We demonstrate its emergence by identifying the shifted free energy computed from the energy flux into the black hole horizon as monotonic distance measure. By decomposing the nonlinear bulk dynamics based on quasinormal modes, we reveal that the anomalous relaxation is governed by a dynamical competition in which the slowest-decaying mode is suppressed while the second mode is amplified. These findings provide a
holographic perspective on the
quantum Mpemba effect in nonequilibrium relaxation involving strongly coupled degrees of freedom.
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All authors Xian-Hui Ge, Shuta Ishigaki, Yu-Qi Lei, Yu Tian
Soft Condensed Matter
Cross-streamline diffusiophoretic migration of colloids in Taylor-dispersed channel flows
Yiran Li, Mobin Alipour and Amir A. Pahlavan
Diffusiophoretic transport of colloids in pressure-driven channel flow is commonly analysed in two limits: an early-time regime in which the solute field is fully two-dimensional, and a late-time macrotransport regime in which cross-sectional homogenization leaves only a weak axial bias on the particles. For colloids, however, many experiments operate in the broad intermediate window \(a^2/D_{\mathrm s}\ll t\ll a^2/D_{\mathrm p}\): the solute has entered the Taylor-dispersion regime, but the particles remain effectively non-diffusive across the gap. We show that the Taylor-dispersed solute retains a residual transverse gradient that is Péclet-enhanced relative to the axial gradient and decays only as \(t^{-1/2}\). This gradient is small in the solute concentration but large enough in \(\nabla\ln c\) to drive cross-streamline migration of colloids. Attractive fronts (\(c_{\mathrm f}>c_{\mathrm i}\)) move particles toward faster centreline streamlines, sharpening the leading edge and accelerating removal; repulsive fronts (\(c_{\mathrm f}<c_{\mathrm i}\)) move particles toward slower near-wall streamlines, broadening the trailing edge and delaying removal. Direct simulations and microfluidic experiments confirm these front-sharpening and front-broadening dynamics. An asymptotic Taylor-regime solute field, combined with a non-diffusive trajectory model, captures the observed front geometries, density profiles, and removal dynamics. The results show that Taylor-dispersed solute fields can remain dynamically two-dimensional for particles, even when their concentration is nearly cross-sectionally uniform.
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Materials Science
Orbital Hall Effect Enables Field-Free Magnetization Reversal in Ferrimagnets without Additional Conversion Layer
Zelalem Abebe Bekele, Kun Lei, Xiukai Lan et al. (+8 more)
The
spin Hall effect provides a well-established route for electrical magnetization control, while the orbital
Hall effect offers a powerful yet less explored source of angular momentum. Achieving field-free deterministic switching in straightforward orbital-torque architectures remains challenging. Here, we demonstrate orbital-
Hall-current-driven switching in a Mo/CoGd
bilayer without the need for a separate orbital-to-
spin conversion layer across a wide temperature range. In this simplified geometry, Mo serves as both an orbital and
spin current source. However, the
spin contribution is insufficient due to weak
spin-orbit coupling, which is consistent with first-principles calculations predicting a large orbital
Hall conductivity. The adjacent ferrimagnetic CoGd layer provides both orbital-to-
spin conversion and the perpendicular switching medium. Planar
Hall and current-induced loop-shift measurements reveal a substantial unconventional z-polarized damping-like torque originating from interfacial
symmetry breaking. Increasing the Mo thickness from 0.2 to 2 nm increases torque efficiency by approximately 31% (y-polarized) and 71% (z-polarized) components. This enhancement enables field-free deterministic switching with a critical current density down to 2.51 x 10^6 A cm^-2. Our results establish Mo/CoGd
bilayers as a compact platform for orbital-current switching and point toward low-power orbitronic
memory devices.
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All authors Zelalem Abebe Bekele, Kun Lei, Xiukai Lan, Xiangyu Liu, Hui Wen, Weihao Li, Yongcheng Deng, Wenkai Zhu, Kaiming Cai, Lishu Zhang, Kaiyou Wang
Materials Science
Long- and Short-Range Anion Order in SrTiO$_{3-x}$H$_x$ Perovskite Oxyhydrides: DFT+$U$ Sensitivity and HSE06 Cluster Expansion
Tzu-chen Liu and Chris Wolverton
Anion ordering in perovskite oxyhydrides can remain significant even in disordered states, particularly at non-dilute hydrogen concentrations. Nevertheless, hydride substitution poses challenges for accurate simulations based on density functional theory due to configurational complexity and Ti 3$d$ reduction. Here, we develop a cluster expansion (CE) framework for SrTiO$_{3-x}$H$_x$ incorporating HSE06 hybrid-DFT energetics. We first demonstrate that calculated mixing energies and ordering stability are highly sensitive to the choice of DFT+$U$, with maximum variations on the order of 100 meV/anion. We
benchmark ordering energetics against HSE06 calculations and identify $U$ = 3.3 eV as an HSE06 proxy, which enables extensive configurational exploration while limiting costly HSE06 calculations to key configurations for efficient learning of ordering energetics. Together, ground-state orderings, correlations between octahedral configurations and structural stability, and MC sampling of CE models all support a strong preference for the O$_4$H$_2$ cis configuration in SrTiO$_{3-x}$H$_x$, in which two hydride ions occupy first-nearest-neighbor anion sites. This cis-type preference was overlooked in previous ATiO$_{3-x}$H$_x$ studies, despite its sizable stabilization of ~200 meV per hydride comparable to reported anion-migration and polaron-formation energies. This study addresses both the previously underexplored sensitivity of CE-based ordering analyses to DFT+$U$ and anion-ordering in perovskite oxyhydrides.
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Materials Science
MatDiffract: A Material-Informed Automated Analysis Platform for X-ray Powder Diffraction
Hongqing Wang, Mingwei Chen, Hongjie Luo et al. (+5 more)
High-throughput experimentation and self-driving laboratories are drastically accelerating materials discovery, yet automated interpretation of X-ray powder diffraction (XRPD) data remains a critical rate-limiting step. Conventional search-match workflows rely heavily on expert manual intervention, while pure data-driven machine learning approaches suffer from limited generalizability across chemical systems and lack rigorous crystallographic interpretability. Here we present MatDiffract, a material-informed automated analysis platform for high-throughput XRPD characterization. Built on a first-principles density functional theory (DFT)-derived inorganic
crystal structure database, Atomly, MatDiffract constructs a perturbation-augmented simulated diffraction database, embeds multi-scale diffraction features into indexable vectors, and integrates hierarchical vector
retrieval with full-pattern fitting Rietveld refinement and quantitative phase fitting. Benchmarked on 875 single-phase experimental patterns, the platform achieves 91.3% Top-1 and 97.2% Top-10 identification accuracy after automated refinement. For binary and ternary multiphase mixtures, it delivers 85.0% and 70.0% Top-1 accuracy with mass fraction mean absolute errors as low as 1.2% and 1.8%, respectively. Beyond mere phase labeling, MatDiffract outputs full crystallographic results including refined structural models, fitted profiles, and quantitative compositions within tens of seconds per sample. Its modular vector-based architecture supports seamless incremental expansion to new material systems, providing an end-to-end solution to close the characterization throughput gap for autonomous materials discovery and high-throughput materials development.
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All authors Hongqing Wang, Mingwei Chen, Hongjie Luo, Wen Yin, Fazhi Qi, Xuqing Chai, Miao Liu, Fengyao Hou
Mesoscale and Nanoscale Physics
Machine Learning for Charge State Characterization of Isolated Double Quantum Dots
Hyma Vallabhapurapu, Marco Candido, Krishna Choudhary et al. (+7 more)
Scaling
semiconductor quantum dot arrays toward fault-tolerant
quantum computing requires efficient tuneup of
spin qubits, a process that depends on the analysis of charge stability maps (CSMs) and remains largely manual. While machine learning has been widely applied to CSM analysis in reservoir-coupled devices, automated tuning in the increasingly important isolated-mode regime has received limited
attention. In isolated-mode CSMs, charge transitions appear as near-vertical lines, making them well suited to compact, task-specific models. We present two convolutional neural networks with fewer than one million parameters, trained on CSMs collected from 32 silicon metal-
oxide-
semiconductor (SiMOS) double-
quantum-dot devices measured at approximately 1 K using an automated cryogenic probing system. Sixteen devices were used for training and sixteen were held out to evaluate cross-device generalization against hand-labeled ground truth. CSMClassifier identifies charge instability and sensor artifacts, achieving 94% macro-averaged accuracy across three quality classes on 2,407 held-out images. ChargeLineNet localizes charge-transition lines and determines electron occupancy, achieving 95.3% exact line-count accuracy on 1,131 held-out images. Combined into a single pipeline, the models correctly determine electron occupancy for 93.8% of clean held-out images. Pre-training on synthetic images substantially improves label efficiency. Fine-tuning the pre-trained model on limited experimental data maintains over 90% accuracy, whereas training from scratch degrades significantly under the same conditions. Together, the two models occupy only 6.5 MB and process images in less than 60 ms on standard laboratory hardware, demonstrating a practical path toward scalable, automated characterization and tuneup of
quantum-dot devices.
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All authors Hyma Vallabhapurapu, Marco Candido, Krishna Choudhary, Paul Steinacker, Ensar Vahapoglu, Chris Escott, Wee Han Lim, Andre Saraiva, Nard Dumoulin Stuyck, MengKe Feng
Mesoscale and Nanoscale Physics
Exceptional Points in a Parallel Double-Quantum-Dot Josephson Junction Coupled to a Ferromagnetic Reservoir
Yiyan Wang, Ruixin Zhou and Bing Dong
We investigate exceptional points (EPs) in a parallel double-
quantum-dot Josephson junction coupled to a dissipative reservoir. By integrating out the leads, we obtain a non-Hermitian Bogoliubov-de Gennes description wherein the superconducting phase difference and orbital flux govern the complex Andreev spectrum. For
spin-independent dissipation, the second-order EPs identified within the infinite superconducting gap limit are eliminated when the finite superconducting gap is properly incorporated. In contrast,
spin-dependent dissipation originating from a
ferromagnetic reservoir, in conjunction with
magnetic flux, gives rise to second-order EPs that persist in superconducting leads with finite gap. Moreover, flux tuning enables the coalescence of two second-order EPs into a third-order EP, whose
eigenvalue splitting exhibits cubic-root scaling behavior. A many-body parity analysis establishes the connection between the contrasting finite-gap behavior and the spectral relationship between the even- and odd-parity sectors. Finally, Josephson currents calculated from both the free-energy derivative and the surrogate-model density
matrix demonstrate consistency and remain continuous across the EPs. These findings establish
spin-selective dissipation and interferometric flux as effective control parameters for robust non-Hermitian singularities in superconducting nanostructures.
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Materials Science
Photo-induced currents and short-term memory for reservoir computing in a ferroelectric semiconductor
Yan Meng Chong, Atreya Majumdar, Manuel Zahn et al. (+3 more)
Physical reservoir computing represents an energy efficient approach for processing temporal signals by exploiting the intrinsic nonlinear dynamics and fading
memory of a physical system. Recently, ferroelectric
semiconductors moved into focus as reservoir materials motivated by their versatile electronic responses to external stimuli. Here, we explore the fundamental possibility to recognize time-varying light pulses via photo-induced currents, using the small-band-gap p-type
semiconductor ErMnO$_3$ as a model system. Under white light illumination, ErMnO$_3$ exhibits non-linearly evolving photo-induced currents and controllable relaxation dynamics that naturally realize the high-dimensional projection and fading
memory capabilities required for reservoir computing. The reservoir capability of ErMnO$_3$ is reflected by the improved recognition accuracy of "Past" input pulses, which increases from ~33% to ~93% after applying reservoir transformation to the input signal. The results present ferroelectric hexagonal manganites as a promising platform for photo-induced current-based reservoir computing and highlight the potential of light-driven
oxide semiconductors for temporal information processing.
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All authors Yan Meng Chong, Atreya Majumdar, Manuel Zahn, Ingvild Hansen, Karin Everschor-Sitte, Dennis Meier