Materials Science
Synthesis and modification of thin NaSICON solid electrolytes using ion beams
Giovanni Ceccio, Jiri Vacik, Ivan Mastronardo et al. (+3 more)
Solid electrolytes (SEs) for sodium-based superionic conductors (NaSICON) were first introduced in 1976 and quickly recognized for their excellent ionic conductivity. While considerable effort has been made to develop thin electrolytes for all-solid-state batteries (ASSBs), only a few sodium-based SEs have been successfully fabricated as thin films. These thin films are particularly desirable for their reduced electrical resistance, which typically increases with the thickness of the SE. By reducing the thickness of the SEs to the nanometer scale, their ionic conductivity can be significantly enhanced. In this study, the NASICON composite was initially prepared in the form of pellets using the mixed oxide technique with a planetary ball mill and synthesized by the solid-state method at 1300 {\deg}C. The resulting pellets were used as sputtering targets in a low-energy ion facility to prepare continuous NASICON nanofilms. To explore the effect of ion implantation on the electrical properties of NASICON, the prepared films were bombarded with Ni ions at 1.1 MeV and varying fluences, using the Tandetron accelerator at the CANAM infrastructure (NPI Řež). The electrical properties of both the synthesized and implanted films were analyzed through electrochemical impedance spectroscopy (EIS). The results, describing the impact of irradiation on NASICON's properties, are presented here.
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All authors Giovanni Ceccio, Jiri Vacik, Ivan Mastronardo, Clausia D Urso, Eva Stepanovska, Romana Miksova
Materials Science
Fabrication framework for three-dimensional colloidal particles with decoupled geometry and material composition
Hamed Almohammadi, Gurminder K. Paink, Vasumathi Venkat et al. (+6 more)
Shape-programmable particles offer significant opportunities for microrobotic systems at the individual level and for hierarchical materials with emergent functionalities arising from collective particle behavior. However, fabricating shape-changing stimuli-responsive particles with complex three-dimensional geometries at colloidal length scales remains a major challenge. Here, we introduce a general fabrication framework that decouples particle geometry from material composition to produce free-standing three-dimensional colloidal particles with complex architectures. Our approach combines soft lithography, swelling-assisted extraction, and sacrificial adhesive transfer to fabricate particles with high
geometric fidelity. We establish a predictive framework that defines the accessible design space for increasingly complex particle geometries. We further extend our framework to fabricate high-aspect-ratio pillar arrays with intricate three-dimensional architectures at colloidal length scales. To demonstrate material versatility, we fabricate particles from both
liquid crystal elastomers and hydrogels. We show reversible shape-changing behavior of
liquid crystal elastomer particles with cylindrical and chiral shapes under thermal and optical stimuli. In suspension, these particles display collective optical dynamic behavior arising from coupling between changes in the programmed
liquid crystal organization within the particles and stimulus-induced
geometric reconfiguration of the particles. Collectively, this work establishes a versatile platform for geometry-programmable colloidal particles with emergent collective functionalities, providing a route toward materials and fluids with dynamically programmable properties.
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All authors Hamed Almohammadi, Gurminder K. Paink, Vasumathi Venkat, Jacopo Movilli, Atalaya Milan Wilborn, Haritosh Patel, Haichao Wu, David Weitz, Joanna Aizenberg
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Quantum States and Spectra of Small Cylindrical and Toroidal Lattices
Caelan Brooks and Kunal K. Das
We examine the spectrum and
quantum states of small
lattices with cylindrical and toroidal
topology subject to a scalar gauge potential that introduces a position dependent phase in the inter-site coupling. Equivalency of gauges assumed in infinite
lattices is generally lost due to the periodic boundary conditions, and conditions that restore it are identified. We trace the impact of various system parameters including gauge choice, boundary conditions and inter-site coupling strengths, and an additional axial field. We find gauge dependent appearance of avoided crossings and persistent degeneracies, and we show their impact on the associated eigenstates. Smaller
lattices develop prominent gaps in spectral lines associated with edge states, which are suppressed in the thermodynamic limit. Toroidal
lattices have counterparts of most of the features observed in cylindrical
lattices, but notably they display a transition from localization to delocalization determined by the relation between the field parameter and the number of
lattice sites.
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Strongly Correlated Electrons
Probing the electronic structure of $\mathrm{UTe}_2$ with ARPES and high-energy spectroscopy
Shin-ichi Fujimori
$\mathrm{UTe}_2$ has emerged as one of the most intensively studied strongly correlated materials in recent years owing to its unconventional superconductivity and the possible realization of a
spin-triplet, topologically nontrivial pairing state. A central open issue concerns the nature of the $\mathrm{U}\,5f$ electrons and their participation in low-energy quasiparticle states. In this review, we summarize recent spectroscopic studies of $\mathrm{UTe}_2$ using momentum-resolved angle-resolved photoemission spectroscopy (ARPES) and element- and configuration-sensitive X-ray probes, including X-ray absorption spectroscopy (XAS), X-ray absorption near-edge structure (XANES), X-ray
magnetic circular dichroism (XMCD), resonant X-ray emission spectroscopy (RXES), and resonant inelastic X-ray scattering (RIXS). A key finding is the pronounced technique dependence of the inferred electronic structure. We synthesize the present spectroscopic picture by integrating these results with modern electronic-structure calculations such as density functional theory plus dynamical mean-field theory (DFT+DMFT). These findings support an intermediate-valence ground state with significant admixture of $5f^2$ and $5f^3$ configurations in $\mathrm{UTe}_2$, and they delineate key experimental and theoretical
benchmarks needed to connect the normal-state electronic structure to the superconducting mechanism.
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Mesoscale and Nanoscale Physics
Interlayer coupling between twisted graphenes through atomically-precise barriers
Yueyang Wang, Ben Fuller, Hongxia Xue et al. (+5 more)
Understanding and controlling interlayer coupling in van der Waals (vdW) materials is crucial for engineering novel electronic phenomena, including correlated states, topological phases, and superconductivity. Twisted bilayer
graphene (TBG) offers a highly tunable platform to explore how interlayer orientation and separation influence
quantum transport and moiré physics. Here, we introduce a method for achieving precise, atomic-scale control of interlayer coupling in TBG using dual-gated devices separated by ultrathin, thickness-tunable hBN spacers. This approach enables systematic control of interlayer interactions, demonstrating that the critical displacement field required for electron-hole bilayer behavior decreases as the layer separation increases at a fixed twist angle. Remarkably, at small twist angles, moiré-related side peaks persist even when layers are separated by tetralayers of hBN (approximately 1.3 nm), indicating robust interlayer band hybridization. By combining atomic-layer-precise control of interlayer coupling with independent twist angle tunability, our platform opens new avenues for discovering novel moiré physics governed by engineered interlayer coupling and moiré patterns.
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All authors Yueyang Wang, Ben Fuller, Hongxia Xue, Tianyu Zhang, Kenji Watanabe, Takashi Taniguchi, Vladimir Fal'ko, Dong-Keun Ki
Materials Science
Polar-Domain Volume as a Unified Descriptor of Transport in Ionic Liquids
Ganesh K. Rajahmundry and Tarak K. Patra
Developing molecular scale structural descriptors that can quantitatively predict the macroscopic transport properties of ionic
liquids remains a longstanding question, owing to the complex interplay between molecular interactions, nanoscale organization, and collective ion dynamics. Here, we use all atom molecular dynamics simulations to establish quantitative structure property relationships between the
equilibrium microstructure and two key transport properties viscosity and ionic conductivity in a series of imidazolium based ILs with chemically distinct anions and varying alkyl chain lengths. While viscosity and ionic conductivity exhibit distinct dependencies on alkyl chain length and anion chemistry, these seemingly different trends largely collapse onto unified correlations when expressed in terms of the mean polar-domain volume. In particular, both transport properties exhibit systematic power-law scaling with the mean polar domain volume fraction, revealing a common structural origin underlying the variations in ion and momentum transport across chemically distinct ILs. These results establish polar-domain volume as a physically motivated molecular-scale descriptor and provide a general structure property framework for connecting nanoscale organization to macroscopic transport properties in ILs.
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Materials Science
Averaging in thermodynamic dislocation theory: general macroscopically uniform stress and strain states
Khanh Chau Le
The averaging procedure, developed for polycrystalline bars under axially symmetric tension or compression, is extended to arbitrary macroscopically uniform stress and strain states. Starting from the equal probability hypothesis for grain orientations, the mean resolved shear stress and the mean resolved elastic and plastic shear strains are defined as root-mean-square averages over all slip-system orientations. Two exact identities for isotropic orientation averages show that the mean resolved shear stress is proportional to the von Mises equivalent stress, and that the direction of macroscopic plastic flow, obtained from the hypothesis that the plastic slip rate on a system is proportional to the resolved shear stress acting on it, is the stress deviator. The result is an associated $J_2$ flow theory whose hardening law is not fitted but follows from the kinetics of thermally activated dislocation depinning and the
evolution equations for the dislocation density and the effective disorder temperature of thermodynamic dislocation theory, written as rates with respect to time so that arbitrary loading paths can be followed. For torsion the theory yields the torque–twist relation of bars and tubes without the classical reductions to a shear stress–strain curve. The parameters for copper are identified jointly from Hopkinson-bar tension, dynamic compression at room and elevated temperatures, and torque–twist records at several twist rates. One set of material parameters, consistent with the earlier compression-only identification, describes tension, compression and torsion from room temperature to $1173$\,K and from $10$ to $2300$\,s$^{-1}$ to $6$\,% rms over 142 data points; the tension–torsion discrepancy noted by Johnson and Cook is traced to the initial dislocation state of their torsion specimens.
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Mesoscale and Nanoscale Physics
Linear and nonlinear transport responses of topological nodal-line semimetals
L. E. Sosa-Arias and A. Martín-Ruiz
Topological nodal-line semimetals are three-dimensional
quantum materials characterized by band crossings that form closed loops in momentum space. In $\mathcal{PT}$-symmetric realizations, these nodal rings are stabilized in the absence of
spin-orbit coupling, giving rise to drumhead surface states and unconventional transport responses. In this work, we study charge transport across a nodal-line semimetal containing a finite electrostatic barrier, with both leads described by the same
equilibrium material. By solving the corresponding scattering problem, we show that the transmission across the barrier exhibits {Klein-tunneling behavior protected at normal incidence by the nodal
topology}, despite the extended nodal-line dispersion, which can be traced back to Berry-
curvature-induced momentum locking. Using the Landauer-Büttiker formalism, we derive general expressions for the linear and nonlinear conductances, including both longitudinal and Hall components, and evaluate them at zero and finite temperature. Our analytical and numerical results elucidate the dependence of the conductance on barrier height and width, as well as on a $\mathcal{PT}$-breaking mass term. We identify distinct transport regimes in which nonlinear contributions are strongly enhanced and transverse Hall currents emerge, providing clear transport signatures of nodal-line
topology and suggesting potential routes toward device applications.
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Materials Science · Cross-listed from cs.LG
A Digital Simulation Toolkit for Physics-Based Generation of Realistic Experimental Scanning Tunneling Microscopy Images
Huanhuan Zhao, Laxmi Bhurtel, Connor Vernachio et al. (+3 more)
Scanning Tunneling Microscopy (STM) is a widely used tool for characterizing surfaces of materials at the atomic scale, playing a crucial role in discoveries across condensed matter physics and materials science. Despite its extreme spatial resolution, STM is one of the most sensitive microscopy techniques and is highly prone to noise. While existing unsupervised denoising methods are very cheap to train, these are primarily focused on removing the noise with minimal recovery of key physical information. While supervised methods can offer superior performance, the major bottleneck is that a large amount of paired clean-noisy experimental images is required which are impractical to obtain. Thus, we developed a low-cost physics-driven digital toolkit to rapidly generate large volume of realistic STM images. Firstly, we simulate clean images from a chosen material system. Then, with prior knowledge of the physical characteristics of the artifacts and noise present in STM experiments, we formulate several artifact-noise functions such as Gaussian electronic noise, 1/f flicker noise, scan-line noise, background tilt and mechanical drift. These physically informed noise components are then added to the simulated clean images to generate realistic STM images. We demonstrated the capability of the proposed digital toolkit to generate AI-ready data for denoising images of the (111) surfaces of copper and lead, while preserving atoms, defects, and electron waves. We also validated the quality of the downstream image analysis of learning electron wave patterns induced by
quantum interference from Cu(111) images. Results show that the supervised models trained on digitally generated AI-ready data can more effectively denoise and learn electron wave patterns on Cu(111) images than benchmarked unsupervised approaches, indicating that the proposed toolkit facilitate scientific discovery.
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All authors Huanhuan Zhao, Laxmi Bhurtel, Connor Vernachio, Fahmy Paiziah, Wonhee Ko, Arpan Biswas
Mesoscale and Nanoscale Physics
Magnetic-field-activated transport from band geometry in gapped nodal-line semimetals
L. Medel Onofre, L. E. Sosa-Arias and A. Martín-Ruiz
We develop a nonperturbative semiclassical theory of magnetotransport in gapped nodal-line semimetals, retaining the full
magnetic-field dependence of Berry-
curvature and orbital-
magnetic-moment corrections. Starting from a minimal two-band model, we derive exact expressions for both the intrinsic Hall response and the dissipative Fermi-surface conductivity, valid to all orders in the
magnetic field within the semiclassical regime. We show that the orbital
magnetic moment reconstructs the geometrically active Fermi surface, breaking the azimuthal cancellation imposed by the nodal-line geometry and thereby activating an intrinsic Hall current that is absent at zero
magnetic field. The Hall response exhibits a pronounced nonmonotonic dependence on the chemical potential and a strongly nonlinear
magnetic-field
evolution, reflecting the redistribution of geometrically active states around the nodal ring. We further demonstrate that the Fermi-surface conductivities recover the conventional Drude behavior in the weak-field limit, while acquiring quadratic and ultimately nonperturbative
magnetic-field corrections together with a field-induced transport anisotropy that gives rise to a measurable planar Hall effect at intermediate fields. Both the intrinsic and dissipative responses are strongly enhanced when the Fermi level lies close to the nodal ring, where Berry
curvature and orbital
magnetic moment are largest. Our results identify
magnetic-field-activated
geometric transport as a characteristic signature of nodal-line semimetals and provide a unified framework for describing magnetotransport beyond perturbative
magnetic-field expansions, together with experimentally accessible signatures of orbital-
magnetic-moment physics.
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Soft Condensed Matter
Mechanical Signature of a Chemically Driven Bath
Tian Huang, Jintae Park, Hyuk Kyu Pak et al. (+1 more)
Using optical tweezers, we demonstrate that the CuAAC click reaction increases the positional fluctuations of a trapped 2 micrometer colloid by at least 20% without altering the trap's corner frequency. This excess variance relaxes to the thermal baseline as reagents are depleted. The additional noise is Gaussian, with a flat power spectrum extending past the corner frequency up to 7 kHz. Notably, the noise amplitude decouples from the macroscale reaction rate, and independent molecular force dipoles are orders of magnitude too small to generate the observed variance. Although the chemical free energy released locally exceeds the energy absorbed by the bead by five orders of magnitude, this energy couples inefficiently. The mechanical action of the reacting bath cannot be represented as a sum of independent molecular events.
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All authors Tian Huang, Jintae Park, Hyuk Kyu Pak, Steve Granick
Materials Science · Cross-listed from cs.RO
A robust single-sensing-element tactile sensor for concurrent pressure and tackiness detection with real-time signal decoupling capability
Ying Yang, Mingwei Gu, Jia-Sen Xie et al. (+8 more)
Integrating tackiness sensation into the artificial skin of humanoid
robots significantly enhances their cognitive and operational capabilities. However existing tactile sensors face challenges in decoupling of the
multimodal signal and stability. Here we present a surface-soft tactile sensor that incorporates a Hall effect sensor and a soft
magnetic composite within a robust elastic framework. The sensor surface indents under pressure and bulges prominently when retracted from sticky surfaces dynamically altering the Hall sensor-magnet distance. This generates whole-process-traceable and baseline-separated signals enabling real-time differentiation between pressure and pull-off force. This single-sensing-element design facilitates bimodal sensing at the same contact spot while eliminate stress cross-talk enhancing both accuracy and sensitivity. The fusion of a robust framework and magneto-mechanical sensing mechanism equips the sensor with exceptional reliability and excellent signal baseline stability. This tactile sensor holds substantial potential for advancing robotic capabilities in evaluating adhesive properties monitoring rubber aging precisely handling lightweight objects and cognizing natural objects surface characteristics.
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All authors Ying Yang, Mingwei Gu, Jia-Sen Xie, Xingyu Ma, Yan-Na Lu, Lin Zheng, Jinhui Gu, Junshuai Chen, Yunjie Lu, Denys Makarov, Jin Ge
Quantum Gases
Generalized Effective Spin-Chain formalism for multicomponent anyons in one-dimensional optical lattices
Sagarika Basak, Xi-Wen Guan and Han Pu
We develop a generalized effective
spin-chain (GESC) formalism for strongly interacting multicomponent anyons in a one-dimensional (1D) optical
lattice. By mapping particle motion onto spinless
fermions and
spin states onto an ordered chain, this framework provides a
spin–charge-separated perspective on the physical effects of fractional exchange statistics. In the strong-interaction regime, the leading-order charge
Hamiltonian becomes independent of the statistical phase; instead, virtual tunneling through doubly occupied states directly imprints this phase on the
spin-exchange coefficients. The GESC formalism captures ground-state properties of the full Anyon–Hubbard model reported in S.~Basak, X.-W.~Guan, and H.~Pu, unpublished manuscript (2026), and reveals that their statistical dependence is predominantly encoded in the explicit anyonic structure of the observables rather than the underlying
spin ground state. This formalism uncovers that, out of
equilibrium, successive
spin exchanges accumulate direction-dependent phases; the resulting interference drives crossover from dispersive to localized impurity transport and generates inversion-asymmetric propagation at intermediate statistics. Suppressed expansion persists for identical and distinguishable impurities, with differences in propagation governed by the interplay between impurity identity and interaction anisotropy. Ultimately, GESC offers a versatile, computationally efficient theoretical framework that connects macroscopic dynamics to microscopic virtual exchange processes, conferring a unique
spin–charge-separated vantage for resolving how fractional exchange statistics survives strong interactions and manifests distinctly across static and dynamical regimes.
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Quantum Gases
Multicomponent anyons in one-dimensional optical lattices
Sagarika Basak, Xi-Wen Guan and Han Pu
We investigate the ground-state and dynamical properties of multicomponent interacting anyons confined in a one-dimensional (1D) optical
lattice. Adopting the Anyon–Hubbard model, we explore
spin and charge correlations as functions of interaction strength and the anyonic statistical parameter. Our results demonstrate that multicomponent effects combined with fractional exchange statistics substantially reshape both charge and
spin correlations. For fractional exchange statistics, the canonical symmetric shell structure with prominent singularities in the spinor fermionic momentum distribution undergoes notable structural reconstruction, exhibiting emergent asymmetry, new spectral peaks, and broadened singular features. Unlike the Tonks–Girardeau bosonic gas, pseudobosons, representing a limiting case of anyons, cease to display a dominant zero-momentum peak. Instead, a quasi-fermionic shell structure emerges with finite-momentum peaks, whose locations are modulated by
lattice site occupancy and interaction strength. The structure factor of
spin correlations uncovers antiferromagnetic ordering in spinor anyon systems, with correlation magnitudes tunable by anyonic exchange statistics. Furthermore, quench dynamics analysis reveals the statistical phase parameter as an effective tuning knob. It enables the switching of dipole oscillations between underdamped and overdamped relaxation regimes and governs overall cloud expansion dynamics. Our findings pave the way for exploring statistics-driven ground-state and dynamical phase transitions in spinor anyon systems.
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Statistical Mechanics · Cross-listed from hep-th
Emergent Symmetries in Ensemble Averages
Masahito Yamazaki
It is widely believed that there are no exact global
symmetries in
quantum gravity. We review recent works showing that global
symmetries can nevertheless emerge after ensemble averages of theories, as encountered in holography. As a precision case study, we discuss the ensemble average of two-dimensional Narain-type conformal field theories associated with an even quadratic form of general signature, which is computed by the Siegel-Weil formula and interpreted as a sum over geometries in a three-dimensional Abelian Chern-Simons theory. Global
symmetries of the bulk anyons can emerge after the average, as T-dualities relating different theories in the ensemble are "folded" into
symmetries of a single theory (duality origami). We discuss the relation to the Swampland program, including the emergence of global
symmetries at infinite distance. Finally, we recast strong-to-weak spontaneous
symmetry breaking (SWSSB) of mixed states as an emergence of
symmetries in ensemble averages; in holography, wormholes connecting the two sides of a thermofield-double construction provide its bulk realization. This motivates a new Swampland
conjecture.
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Materials Science
Frustrated Gd3+ Double Perovskites as High-Performance Magnetocaloric Materials for Sub-100 mK Adiabatic Demagnetization Refrigeration
Tim Treu, Marvin Klinger, Christian Heil et al. (+6 more)
Achieving temperatures below 100 mK is essential for advancing
quantum technologies and exploring fundamental
quantum phenomena. While paramagnetic salts have traditionally enabled adiabatic demagnetization refrigeration (ADR), their limitations have driven the search for more effective alternatives. In this work, we present Gd3+-based double perovskites, Ba2GdSbO6 and Sr2GdSbO6, as high-performance magnetocaloric materials. Starting ADR from 2 K and 5 T, these compounds reach 67 mK and 68 mK in small finite
magnetic fields, and 83 mK and 78 mK in zero field, respectively, which are the lowest reported ADR temperatures for Gd3+ magnets (S = 7/2) under these conditions. The frustrated geometry and the complex interplay of exchange and dipolar interactions suppress their antiferromagnetic ordering temperatures to 100 and 166 mK for Ba2GdSbO6 and 190 mK for Sr2GdSbO6, while maintaining an outstanding
entropy density of 189 mJ K-1 cm-3 and 201 mJ K-1 cm-3, respectively. Notably, Ba2GdSbO6 sustains sub-100 mK cooling even at finite fields of 0.5 T, making it particularly promising for practical ADR applications.
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All authors Tim Treu, Marvin Klinger, Christian Heil, Hans-Albrecht Krug von Nidda, Vinicius E. S. Frehse, Mamoun Hemmida, Anton Jesche, Alexander A. Tsirlin, Philipp Gegenwart
Superconductivity
Evanescent-wave Johnson Noise from Superconductors
Hruday Mallubhotla, Gustav Romare, Ilya Esterlis et al. (+3 more)
We compute the evanescent-wave Johnson noise (EWJN) in the
vacuum half-space above a
superconductor, and the resulting relaxation time ($T_1$) of
spin and charge
qubits placed at nanometer distances from the surface. The electromagnetic response is described by a single microscopic transverse current-response kernel $Q(q, \omega)$ for a BCS
superconductor. This is computed for varying densities of both non-
magnetic impurities and
magnetic impurities, for arbitrary frequency and temperature and for wave vectors $q \ll k_F$ (the Fermi wavevector). When combined with the fluctuation-dissipation
theorem and the nonlocal surface impedances of the half-space, this yields the
magnetic and electric field noise at any distance $z \gg k_F^{-1}$ from the surface, from which we obtain $T_1$. Just below $T_c$ the
magnetic noise is enhanced relative to the normal state by the coherence (Hebel-Slichter-type) peak of the dissipative conductivity and drops exponentially at lower temperatures; the electric noise shows no coherence peak. The theory predicts that there is a zero-temperature noise floor induced by
magnetic impurities. In the gapless regime produced by pair breaking, the finite subgap density of states $\nu(0)$ yields a temperature-independent noise spectral density and a relaxation rate bounded by $T_1^{-1}(T)\le[\nu(0)/\nu_F]^{2}\,T_{1,N}^{-1}(T)$ for $T\ll T_c$, with equality in the extreme nonlocal regime. Here $\nu(0)$ and $\nu_F$ are the superconducting and normal-state densities of states at the Fermi energy, and $T_{1,N}(T)$ is the relaxation time the same electrode would produce in its normal state at the same temperature.
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All authors Hruday Mallubhotla, Gustav Romare, Ilya Esterlis, Maxim Vavilov, Robert Joynt, Alex Levchenko
Materials Science
Enabling the Ambient Pressure Growth of ScB2 Crystals for AlGaN Power Electronics
Satya K. Kushwaha, Ahamed Raihan, Astrid D. Kengne et al. (+19 more)
Here we report the growth of single crystalline ScB2, an ultrahigh-temperature ceramic, at ambient pressure in a
laser-heated Optical Floating Zone via the travelling solvent method.
Crystals have been grown from both Sc-rich (55-65 at% Sc) and B-rich self-flux (80-83 at% B) at growth rates in the range of 0.2-2 mm/hr. The structure of grown
crystals is in good agreement with an AlB2-type layered hexagonal phase, space group P6/mmm, with
lattice constants a = 3.1423(2) Å\ (resp. 3.1502(3) Å) and c = 3.5084(3) Å\ (resp. 3.5041(3) Å) for
crystals grown under Sc-rich (resp. B-rich) conditions.
Crystals natively grow along the in-plane [100] direction. Electron backscattered diffraction shows that Sc-flux growth results in boules with multiple domains containing Sc inclusions, with the domains highly aligned. In contrast, B-flux boules are single domain after the initial nucleation region. Rocking-curve measurements of B-flux
crystals for the (h000) and (000l) reflections show single peaks, establishing that the
crystals are free from grain boundaries; the asymmetry in the scattered-intensity tails suggests the presence of point defects. Surface X-ray photoemission spectroscopy shows that the electronic environment in B-flux
crystals is superior to that of Sc-flux
crystals and produces highly resolved binding-energy peaks for B 1s and Sc 2p. Work-function measurements for the (11-20) plane give a value of approximately 5 eV, consistent with the highly electrically conductive nature of ScB2. These results demonstrate the viable ambient-pressure growth of ScB2, establish it as a
lattice-matched substrate candidate for Al-rich AlGaN power microelectronics, and show that this growth route enables scalable manufacturing of ScB2 substrates.
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All authors Satya K. Kushwaha, Ahamed Raihan, Astrid D. Kengne, Daniel Joel Harrison, R. Shipra, Han Xie, Evan N. Crites, Allana G. Iwanicki, Luke J. Meiler, Sharad Mahatara, Maxime A. Siegler, Renae N. Gannon, Steven R. Spurgeon, Rajeswari Kolagani, Amitayush Jhu Thakur, Stephan Lany, Patrick E. Hopkins, Jessica L. McChesney, Nancy Haegel, Tyrel M. McQueen, Michael G. Spencer, MVS Chandrashekhar
Mesoscale and Nanoscale Physics
Effects of Longitudinal Spin Current Density Gradient on Spin-Orbit Torque Switching of Perpendicular Magnetization
Guowen Gong, Qianbiao Liu and Lijun Zhu
It has remained a critical open question as to whether a longitudinal
spin current gradient (e.g., due to a gradient in the thickness, composition, or width) can replace the longitudinal
magnetic field required for deterministic
spin-orbit torque switching of normal metal/ferromagnet
heterostructures with perpendicular
magnetic anisotropy. Here, we report robust micromagnetic and experimental evidence that any realistic longitudinal
spin-current density gradient cannot be an effective replacement for a longitudinal
magnetic field to enable deterministic switching of a perpendicular
magnetic anisotropy device. Instead, the longitudinal
spin current density can only modify the nucleation and pulse-timing-sensitive oscillations of
magnetic domains and thus the picosecond-scale strip-like indeterministic switching windows. The same conclusions hold robustly when the transverse effective field associated with the
spin-current pulse (the sum of the Oersted field and field-like torque) is taken into account. The indeterministic switching prevents applications in the presence of finite device-to-device variations and drifts in write current pulse and thermal fluctuations of device parameters. We also experimentally show that, instead of a longitudinal
spin current density gradient, perpendicular
spins are much more effective in deterministic switching of perpendicular
spin torque devices.
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Statistical Mechanics
Crossover of Scaling Behaviors of Work Cumulants in a Driven Gaussian Field Theory
Yanbo Qiao, Ruohan Xu and H. T. Quan
We derive the finite-temperature characteristic function of work (CFW) for a driven $O(N)$ Gaussian field theory and obtain closed-form expressions for all zero-temperature excess-work cumulants. For gapped protocols, we use adiabatic perturbation theory (APT) to derive the $\tau_Q^{-2}$ scaling for protocols with a nonzero first derivative at either boundary, where $\tau_Q$ is the protocol duration; smoother boundaries lead to faster decay. For power-law protocols approaching the critical point with exponent $p$, we determine the competition between critical excitations and the regular contribution. The $n$th cumulant's critical contribution follows Kibble–Zurek (KZ) scaling $\tau_Q^{-p(d+n)/(p+2)}$ for $d+n<2p+4$, acquires a logarithmic correction $\tau_Q^{-2p}\log\tau_Q$ at $d+n=2p+4$, and scales as $\tau_Q^{-2p}$ above this condition, where $d$ is the spatial dimension. This analytical study of the APT–KZ crossover in a solvable model provides a basis for studying their competition in interacting field theories.
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Materials Science
From Automated Simulation to Autonomous Discovery: A Hierarchical Framework for Agentic Computational Materials Science
Linggang Zhu, Jian Zhou and Zhimei Sun
The convergence of large
language models, materials-specific foundation models, and agentic artificial intelligence is reshaping the paradigm of computational materials discovery. While high-throughput computation, automated workflows, and data-driven modeling have greatly expanded the scale of materials exploration, the core scientific decision-making loop remains largely human-directed. Agentic AI introduces the possibility of systems that can autonomously reason about materials objectives, execute simulations, and refine strategies. However, the rapid emergence of such systems has created a critical need for a unified and operational framework to define, evaluate, and guide scientific autonomy in computational materials discovery. In this Perspective, we propose the Computational Materials
Agent Autonomy Level (CMA-AL) framework, a hierarchical taxonomy defining six levels of autonomous agency in computational materials science: scripted excecutor, LLM-assisted operator, adaptive explorer, experiment-ready modeler, agentic digital twin, and self-extending intelligence. We further map emerging agentic systems onto the framework and identify key scientific and technological challenges toward higher autonomy. CMA-AL provides a common
language for characterizing agentic computational materials discovery, evaluating the maturity of emerging systems, and guiding their
evolution toward increasingly autonomous materials discovery.
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Materials Science
Orbital-engineered px,y-kagome lattice in a halogen monolayer
Xulin Liu, Jingyi Duan, Yueqian Chen et al. (+11 more)
Multi-orbital kagome
lattices with explicit orbital degrees of freedom remain largely unexplored, as most experimentally realized systems rely on complex d-electron
manifolds that are approximated by isotropic single-orbital models. Here, we overcome this limitation by realizing a px,y-orbital kagome
lattice through deposition of a Br monolayer on Ag(111), where orbital filtering selectively suppresses the pz channel. Scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and density-functional-theory calculations reveal a large-area, highly ordered kagome structure whose band dispersions quantitatively match the anisotropic px,y tight-binding model. To extract the intrinsic
manifold from the substrate background, we construct an effective H-passivated model, which uncover the intrinsic electronic structure and reveals nontrivial topological characteristics of the px,y kagome
manifold driven by first-order
spin-orbit coupling effect. Our work establishes Br/Ag(111) as an experimentally accessible platform for multi-orbital kagome physics, extending the kagome paradigm from the conventional d-orbital regime to an orbitally engineered topological setting.
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All authors Xulin Liu, Jingyi Duan, Yueqian Chen, Wenbo Liu, Peiyao Xiao, Yuxiang Liu, Pei Liu, Minjun Wang, Baojie Feng, Dongfei Wang, Xun Shi, Wei Jiang, Yugui Yao, Wende Xiao
Statistical Mechanics
Derivation of the General Solution of the Black-Scholes Boundary-Value Problem
ByoungSeon Choi and M.Y. Choi
There are infinitely many functions that satisfy the Black-Scholes partial differential equation and the terminal condition corresponding to the European call option. This means that the Black-Scholes formula, which led to the award of the 1997 Nobel Prize in Economic Sciences, is not the unique solution, as was once assumed. Consequently, it violates the law of one price, one of the fundamental laws of economics and finance. In this article, we present a rigorous derivation of these solutions to the Black-Scholes boundary value problem.
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Statistical Mechanics
Localization Transition in Kinetically Deformed one-dimensional Aubry-André Model
Arpita Goswami
We propose a $q$-deformation in the single-particle kinetic energy and investigate how it modifies the localization in the one-dimensional Aubry-André (AA) model. We construct a Hermitian $q$-deformed kinetic operator as a nonlinear function of the
lattice translation operator, preserving the uniform
lattice and recovering the conventional AA
Hamiltonian continuously in the undeformed limit $q\to1$. The deformation generates an infinite set of correlated odd-range kinetic processes, controlled by a single parameter q, rather than phenomenologically involving long-range hopping. Under the dual transformation, this long-range hopping appears as higher harmonics of the dual quasiperiodic potential, providing a controlled route for breaking the exact self-duality of the AA model, with $q$ as the control parameter, consequently modifying the localization structure for $q\neq1$. In contrast to the conventional AA model, where all eigenstates localize simultaneously at $\lambda_c=2$, the deformed model exhibits a fraction of delocalized states even beyond $\lambda_c =2$. An intermediate regime also emerges in the $q-\lambda$ plane where localized and extended eigenstates coexist across the spectrum. We also propose a possible experimental realization of the hierarchy produced in the $q$-deformed kinetic setting in a periodically driven AA model.
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