Superconductivity
Out-of-equilibrium relaxation dynamics of the superconducting order parameter in CsV$_3$Sb$_5$
Avi Shragai, Alexander Won, Jonathan M. DeStefano et al. (+4 more)
The application of a time-varying strain field drives a superconducting order parameter out of
equilibrium. How the order parameter relaxes back to
equilibrium depends both on the structure of the superconducting gap and on the nature of quasiparticle scattering. We report the discovery of an ultrasonic attenuation peak inside the superconducting state of the kagome
superconductor CsV$_3$Sb$_5$. This peak is the natural consequence of the order parameter relaxation time matching the ultrasonic drive frequency near $T_{\rm c}$. From the measured frequency dependence of the peak, we extract a microscopic scattering time of $\tau_N = 25$ ps. This timescale is two orders of magnitude longer than the elastic scattering time as determined by resistivity measurements, but is comparable to the inelastic scattering time determined by thermal transport. Within the conventional framework of order-parameter relaxation, this implies that elastic scattering is ineffective at relaxing the superconducting condensate, consistent with a sign-preserving $s$-wave state obeying Anderson's
theorem.
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All authors Avi Shragai, Alexander Won, Jonathan M. DeStefano, Andrea Capa Salinas, Ganesh Pokharel, Stephen D. Wilson, B. J. Ramshaw
Mesoscale and Nanoscale Physics
Bridging steady-state and time-domain descriptions of molecular electron transport
Thibaut Lacroix, Namgee Cho, Clemens Vittmann et al. (+3 more)
Electron transmission from an input electrode, through a molecular system, to an output electrode has been widely studied using the steady-state non-
equilibrium Green's function (NEGF) method. Recently, the wave packet method, which provides access to the transient dynamics of electrons as well as internal molecular degrees of freedom, has been employed to investigate enantiospecific electron transport through chiral molecules. In this work, we derive the quantitative relation between the transmission of a finite-size wave packet and the energy-resolved NEGF transmission, showing that the former corresponds to a spectral average of the latter weighted by the wave packet energy distribution. Exploiting this correspondence, we construct non-Gaussian auxiliary wave packets whose spectral weight encodes the Landauer energy-window, allowing current-voltage characteristics to be obtained directly from time propagation. We further show that the correspondence extends to
spin-resolved transport in a
spin-
phonon model of chirality-induced
spin selectivity.
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All authors Thibaut Lacroix, Namgee Cho, Clemens Vittmann, James Lim, Susana F. Huelga, Martin B. Plenio
Strongly Correlated Electrons
Acoustic Wave-Function Imaging of Sublattice Physics in a Kagome Lattice
L. Müller, N. Endres, B. Geldiyev et al. (+4 more)
The canonical kagome band structure hosts a Dirac cone, saddle-point van Hove singularities (vHS), and a flat band. Characteristically, these features exhibit distinct sublattice localization within the three-site basis of the kagome
lattice. However, experimental proof of this sublattice character is challenging and requires direct access to both the real-space wave function and its associated momentum-space texture. Here, we implement an acoustic kagome
lattice on the cm scale and measure the full excitation spectrum, thereby imaging the wave function at each
lattice site, including both amplitude and phase. This enables investigation of the momentum-dependent sublattice texture across the complete band structure, particularly at the flat band and at the mixed- and pure-sublattice van Hove singularities. Our results are in excellent agreement with minimal tight-binding model calculations and constitutes the first direct experimental observation of the sublattice-resolved band structure in a kagome
lattice.
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All authors L. Müller, N. Endres, B. Geldiyev, S. Widmann, K. Burkard, M. Ünzelmann, F. Reinert
Strongly Correlated Electrons
Certified reduced-basis emulation of conformal field theories on the fuzzy sphere
Virgil V. Baran
Fuzzy-sphere regularization gives numerical access to three-dimensional conformal field theories (CFTs), but locating one requires testing for criticality across the parameter space of microscopic couplings. We reduce the search cost by about two orders of magnitude, combining an exact diagonalization based on states having definite total angular momentum with a certified reduced-basis emulator that reconstructs energies, observables and their derivatives continuously across the couplings from a handful of exact solutions per system size. The combination reproduces the published ground-state-energy analysis of the fuzzy-sphere Ising model and the published conformal data of a three-flavor fuzzy-sphere realization of the O(2) Wilson–Fisher CFT, including quantities defined by parameter derivatives. Applied to the O(2) model with no CFT input, the ground-state-energy criterion locates the critical coupling to within half a percent of a density
matrix renormalization group value obtained on systems more than twice the size, and maps the critical line of the model across the coupling plane. Ground-state criteria locate the critical line robustly, but the point they select along it is weakly determined, and the computed dimensions come closest to the bootstrap elsewhere along the line.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Nonlinear dynamics and mechanical frequency combs with a Meissner-levitated micromagnet
Yiqi Wang, Trisha Madhavan, Vanessa Wachter et al. (+6 more)
Nonlinearities in multimode mechanical systems can give rise to rich dynamical phenomena with great potential for sensing applications and for future
quantum experiments. We demonstrate that the coupled center-of-mass and rotational motion of a Meissner-levitated micromagnet offer a promising platform for nonlinear dynamics, combining low dissipation,
magnetic tunability, strong intrinsic Duffing nonlinearities, and nonlinear intermodal couplings. We use this tunability to demonstrate the generation of a mechanical frequency comb in the micromagnet dynamics, realized by parametric excitation of two translational modes followed by cascaded nonlinear frequency mixing, which produces a phononic comb with tunable spacing. At large amplitudes, nonlinear coupling to a low-frequency librational mode of the magnet leads to parametric excitation and phase locking of that mode, generating a dense spectral fine structure at subharmonics of the drive. These results establish levitated micromagnets as a platform for nonlinear multimode mechanics, with potential applications in precision sensing and
quantum-limited metrology.
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All authors Yiqi Wang, Trisha Madhavan, Vanessa Wachter, J. DaLi Schaefer, Addison NewRingeisen, Zhiyuan Wei, Frankie Fung, Benjamin A. Stickler, Mikhail D. Lukin
Materials Science
Competition between vacancy creation and filling in defect-engineering of hBN
Shrirang Chokappa, Manuel Längle, Barbara Maria Mayer et al. (+13 more)
Hexagonal boron nitride (hBN) has recently become the focus of intense research as a material that can host
quantum emitters. It is known that such emission is related to point defects, but in order to conclusively correlate specific defects to their spectra, having control over the defect creation mechanism is required. Here, we prepare freestanding, monolayer hBN samples and irradiate them with ultra-low-energy (150 eV) Ar+ ions. The samples are characterized before and after irradiation via scanning transmission electron microscopy to assess the defect density and distribution. Contrary to what analytical potential molecular dynamics simulations have predicted, we predominantly observe boron single vacancies after ion irradiation, followed by double vacancies at half the count. Moreover, we also observe that vacancy filling with Si and C impurity atoms plays a more significant role in the created defects than previously assumed, potentially posing a problem for selective creation of
quantum emitters in hBN.
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All authors Shrirang Chokappa, Manuel Längle, Barbara Maria Mayer, Vladimir Zobač, Jacob Madsen, Diana Propst, David Lamprecht, Philipp Irschik, Arixin Bo, Clara Kofler, Vinzent Hana, Fabian Kraft, Clemens Mangler, Lado Filipovic, Toma Susi, Jani Kotakoski
Materials Science
High-throughput thermodynamic screening of oxide-scale adhesion across the CoCrFeMnNiAl high-entropy alloys
Dennis Boakye and Chuang Deng
One significant benefit of reactive element (RE) additions is the colossal improvement in oxide-scale retention during high-temperature oxidation. Selecting optimal RE dopants in high-
entropy alloys remains empirical because the relevant thermodynamic landscape is inaccessible to first-principles at the required compositional resolution. Here we apply the macroscopic atom model, coupled with McLean isotherm and Guttmann models, to screen adhesion across nine CoCrFeMnNiAl sub-families at \ce{Cr2O3} and \ce{Al2O3} interfaces, ranking five REs (Hf, Y, Zr, La, Ti) for segregation, adhesion enhancement, and sulfur displacement. The screening reveals an oxide-dependent ranking inversion, with Hf dominating at \ce{Cr2O3} and La dominating at \ce{Al2O3}, driven by the interplay between RE–O and RE–
matrix interaction enthalpies. Mn-containing
alloys exhibit intrinsic sulfur resistance, consistent with their experimentally observed oxidation characteristics. A sulfur immunity phase diagram identifies compositions with Al~+~Mn~$\gtrsim$~25~at% as thermodynamically immune to S-induced adhesion loss. All crossover concentrations collapse onto a universal exponential governed by the segregation enthalpy difference, providing a transferable design rule. Inverse design identifies \ce{Co16Cr16Fe16Ni16Al35} as the optimal S-immune composition with $W_\text{sep} = 5.95$~J/m$^2$ without RE doping.
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Mesoscale and Nanoscale Physics
Phase-Controlled Majorana Zero Modes in Altermagnetic Topological-Insulator Josephson Junctions
Hao Dong, Xun-Jiang Luo, Xiao-Hong Pan et al. (+1 more)
We exploit facet-dependent Andreev phase shifts to control topological superconductivity with a phase bias in a three-dimensional altermagnetic topological-
insulator Josephson junction. In the weak link between two conventional $s$-wave
superconductors, the $d$-wave altermagnetic order produces anisotropic momentum shifts of the surface Dirac cones. The resulting net momentum of the states involved in Andreev reflection generates additional propagation phases that differ between facets. Consequently, the facet-resolved Andreev spectra exhibit gap closings at distinct phase biases, giving rise to topological superconducting regimes that host Majorana zero modes (MZMs). We further show that the spatial locations of the MZMs can be controlled by the phase bias. Moreover, these topological superconducting transitions are only weakly affected by moderate variations in the chemical potential, obviating the need for fine-tuning to the Dirac point. Our results establish a platform for realizing and spatially controlling MZMs by tuning the superconducting phase bias in altermagnetic topological-
insulator Josephson junctions.
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All authors Hao Dong, Xun-Jiang Luo, Xiao-Hong Pan, Xin Liu
Materials Science · Cross-listed from physics.chem-ph
Breaking Water at Graphene Defects
Samuel G. H. Brookes, IniOluwa C. Popoola, Fabian Berger et al. (+3 more)
Water dissociation at solid surfaces underpins processes ranging from corrosion and catalysis to electrochemistry and photovoltaics. Defects often serve as reactive sites for dissociation, yet how solvation influences water dissociation at such sites remains poorly understood. Here, we use state-of-the-art machine-learned interatomic potentials to explore water dissociation at defective
graphene-water interfaces. We show that solvation qualitatively changes the reaction mechanism at a
graphene single vacancy (SV), opening pathways that are absent for an isolated water molecule. Whereas the gas-phase process proceeds via a single concerted channel, the solvated SV splits water through two competing pathways: a basic route forming SV-H and OH-(aq), and an acidic route forming SV-OH and H3O+(aq). These lower-barrier pathways produce distinct chemisorbed intermediates that enhance
graphene-water adsorption. Accordingly, even a simple carbon vacancy gives rise to unexpectedly rich interfacial chemistry, coupling surface chemistry to interfacial charge and wettability, with implications for carbon functionalization and nanofluidic transport.
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All authors Samuel G. H. Brookes, IniOluwa C. Popoola, Fabian Berger, Kara D. Fong, Angelos Michaelides, Christoph Schran
Strongly Correlated Electrons
Robust Spin-1 Haldane Topology under Itinerant Doping
Satoshi Nishimoto
We study itinerant hole doping of the
spin-$1$ Haldane
symmetry-protected topological (SPT) phase in two $t$–$J$ chains coupled by ferromagnetic (FM) Hund exchange. Density-
matrix renormalization group calculations show that string order, a finite
spin gap, and the Haldane
entanglement structure coexist over a broad doping range. Combined with
entanglement-
entropy scaling consistent with a single gapless charge mode, these results support a metallic doped Haldane SPT with a $C1S0$ low-energy description. At low doping, short-range charge correlations reduce the density of
spin-$1/2$ defect rungs, whereas at larger doping their positions become nearly uncorrelated while their
spins are collectively incorporated into the correlated
spin sector. The doped Haldane SPT terminates in a fully
spin-polarized FM phase, which forms a reentrant pocket at high doping in the global phase diagram. Dilute-limit analyses trace the two FM boundaries to
spin–charge factorization at weak Hund coupling and to rung-triplet binding with reduced pair mobility at strong Hund coupling. Our results show how mobile carriers reorganize the Haldane
spin structure while preserving its characteristic signatures.
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Materials Science
Effect of Stress and Surface Roughness on Electrodeposition in All-Solid-State Batteries: A Computational Investigation
Kaniza Islam, Ayush Morchhale, Jung-Hyun Kim et al. (+2 more)
All-solid-state batteries (ASSBs) promise high energy density and enhanced safety, but their development is hindered by instability and incompatibility at solid-solid interfaces. In Li-metal ASSBs, lithium penetration occurs despite stiff ceramic electrolytes via grain boundaries, often initiated by minor Li/SE interfacial irregularities. Here we introduce a two-dimensional continuum model with electro-chemo-mechanical coupling to investigate interfacial current distribution in Li ASSBs with surface-roughened argyrodite electrolyte under stack pressures and applied current density. Our theoretical analysis and simulation studies highlight the critical role of mechanical stress in interfacial current distribution. We find that prominent stress variations around elongated surface protrusions are the key to nonuniform Li deposition, without which Li deposition becomes uniform even on a rough surface. Moreover, our parametric study elucidates that stress effects dominate the overpotential and current distribution under low interfacial current density to exchange current density ratios, otherwise the high interfacial resistance due to surface-roughness-induced interfacial area becomes dominant. With these insights, we also discuss the potential of engineering artificial interlayers to modulate interfacial current distributions, offering guidance for improving the long-term performance and reliability of ASSBs.
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All authors Kaniza Islam, Ayush Morchhale, Jung-Hyun Kim, Yanzhou Ji, Noriko Katsube
Quantum Gases
Finite-time effects in periodically kicked systems
F. Revuelta, R. Chacón and F. Borondo
In this work, we study finite-time effects in ultracold atomic systems by considering time-dependent modulations with variable waveforms and durations. These two characteristics can be controlled by adjusting only a single parameter. For arbitrarily short pulses, our model recovers the paradigmatic kicked rotor while maintaining the impulse transmitted per period and unit amplitude constant. Furthermore, we demonstrate that finite-time effects have a profound impact on dynamical localization, a result that cannot be captured by the {\delta}-kicked-rotor model. Through a detailed analysis of the effects of different modulation amplitudes, periods, and waveforms, we identify the conditions for which dynamical localization is significantly enhanced. We show that the strength of dynamical localization increases sharply as the system approaches the {\delta}-kicked-rotor limiting case. Moreover, we establish the existence of an optimal value of the period that maximizes dynamical localization for given values of the amplitude and shape parameter.
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Materials Science
Skyrmion nucleus resolves the Landauer paradox
Jiyuan Yang, Denan Li and Shi Liu
Ferroelectric switching is among the most fundamental and widely studied
symmetry-breaking processes in physics. However, the Landauer paradox asserts that an ideal single-domain ferroelectric should be kinetically unswitchable, because a three-dimensional reversed
nucleus would carry a prohibitive depolarization penalty, leading to unphysically large coercive field (the electric field required to switch the polarization). Here we show that this long-standing paradox is resolved by
topology. In defect-free PbTiO3, large-scale molecular dynamics simulations reveal that the intrinsic critical
nucleus is a three-dimensional polar skyrmion. Its continuous polarization rotation and Néel-type boundary walls self-compensate bound charge, suppressing the depolarization energy by orders of magnitude and bringing the predicted coercive field into agreement with experiment. This topological
nucleus further overturns the 60-year-old Janovec-Kay-Dunn law. We derive an analytical thickness-dependent coercive-field law governed by field-induced softening of the parent ferroelectric state and controlled by a single material descriptor. This framework captures diverse experimental trends across ferroelectric families and recasts the Kay-Dunn exponent of -2/3 as an effective finite-window behavior. These results establish polar
topology as an organizing principle for intrinsic switching and suggest that hidden topological transition states may broadly shape nonequilibrium phase transformations traditionally understood as Landau-type
symmetry breaking.
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Mesoscale and Nanoscale Physics
Néel-Vector-Dependent Altermagnetic Spin Splitting in the One-Dimensional Limit
Xin Chen and Duo Wang
Altermagnetism is normally identified by nonrelativistic
spin-split bands in a compensated collinear magnet. Under one-dimensional confinement, however, this diagnostic can disappear: a boundary-compatible sublattice-exchange operation may leave the only Bloch momentum unchanged, forcing the nonrelativistic
spin-up and
spin-down spectra to coincide. We show that nonrelativistic
spin degeneracy can coexist with relativistic
spin splitting in a compensated one-dimensional magnet. In a Lieb-based construction, confinement along the diagonal cancels the projected $d$-wave
spin splitting while preserving the real-space sublattice-exchange motif.
Spin-orbit coupling (SOC) then locks
spin to the
lattice, so the Néel-vector orientation selects a
magnetic line group that can reveal
spin-split bands. Using fully compensated $[110]$ Ta$_2$TeSeO nanoribbons as a prototype, we find
spin-degenerate nonrelativistic bands and sizable SOC splitting in the inherited easy-axis domain, $\mathbf N\parallel[100]$ or $[010]$. For sufficiently wide ribbons that retain the parent easy-axis order, this splitting is an
equilibrium property. The easy-axis ribbon also supports a right-moving-mode
spin polarization of about $35\%$ at finite ideal conductance. Our results establish one-dimensional fully compensated altermagnetic functionality hidden inside apparently conventional antiferromagnetic bands.
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Materials Science · Cross-listed from physics.optics
Antimony for broadband nanophotonics across the ultraviolet, visible and infrared
Fernando Chacón-Sánchez, Jacek Wojcik, Marina García Pardo et al. (+5 more)
Semimetal elemental antimony (Sb) nanostructures show great potential for applications where nanophotonic properties play a key role, such as phase-change optical
memories, non-linear optical elements, photothermal therapy
agents, photodetectors and photocatalysts. However, designing advanced Sb-based photonic devices critically requires an accurate and reliable knowledge of the optical response of bulk and nanoscale Sb. Herein, we report for the first time a fully consistent and accurately measured dielectric function for Sb nanoscale films in a wide spectral range from the ultraviolet to the far infrared (4 - 0.04 eV, i.e. ~ 0.3 - 30 $\mu$m), surpassing previous reports that explored a limited spectral range. It is found that the Sb spectral response is driven exclusively by giant interband transitions in the visible up to mid infrared (4 - 0.4 eV, i.e. ~ 0.3 - 3 $\mu$m), and that their contribution dominates over that of free carriers down to 0.12 eV (i.e. ~ 10 $\mu$m). Such spectral response enables Sb nanostructures to display spectrally selective and tunable nanophotonic resonances. First, we showcase interband plasmonic resonances in the visible-to-near infrared for Sb nanogratings. Second, we report giant refractive index dielectric resonances in the mid infrared for nanostructured Sb/dielectric/metal resonant cavities. These findings open a pathway to optimized planar Sb nanoscale designs enabling a tailored light-matter interaction, which will be useful for integrated data, telecom, medical, optoelectronic and energy conversion devices operating in a broad spectral range.
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All authors Fernando Chacón-Sánchez, Jacek Wojcik, Marina García Pardo, Fátima Cabello, Peter Mascher, Fernando Agulló-Rueda, Rosalía Serna, Johann Toudert
Statistical Mechanics
Work as a function of protocol duration for the efficient erasure of an underdamped memory: isothermal to adiabatic transition
Nicolas Barros, Stephen Whitelam, Sergio Ciliberto et al. (+1 more)
We use evolutionary reinforcement learning to determine efficient time-dependent erasure protocols for an underdamped cantilever moving in a double-well potential, an experimental realization of a 1-bit
memory. We investigate how the mean work $\langle W \rangle $ needed to erase a bit scales as a function of the protocol duration $\tau$. We find two regimes, depending on how $\tau$ compares to the relaxation time of the system $t_r$. For $\tau \gg t_r$, the quasistatic isothermal regime, we recover Landauer's bound plus an overhead that scales as $1/\tau$, similar to the overdamped case. By contrast, for $\tau<t_r$ erasure becomes adiabatic and $\langle W \rangle$ grows more slowly than in the isothermal case. This growth is bounded from below as $1/\tau$, which we derive using a gedanken optimal protocol. Finally, comparison with overdamped erasure shows that learned protocols can outperform protocols that are optimal subject to
equilibrium boundary conditions.
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All authors Nicolas Barros, Stephen Whitelam, Sergio Ciliberto, Ludovic Bellon
Strongly Correlated Electrons
Topological band structure of excitons in octochlore KTb$_{3}$F$_{10}$: an analog of the Luttinger Semimetal
Olivier Demortier, Françoise Damay, Paul McClarty et al. (+3 more)
Understanding the
symmetry and
topology of band structures in crystalline solids has been among the defining themes of a generation of condensed matter physicists, with implications across many different platforms including electronic bands, photonic
crystals,
phonons and
magnetic excitations. In the latter systems, there is usually
magnetic long-range order and time reversal
symmetry breaking. Here we further enrich the possible band structures available to
magnetic systems by examining dispersive
crystal field excitations above a ground state that is a simple product of singlets. In these systems, there is an interplay of
magnetic interactions and band
topology with both
crystal and time reversal
symmetries. Using high-resolution
neutron spectroscopy we reveal the dispersion relations of bosonic
excitons in KTb$_{3}$F$_{10}$, an experimental realization of the octochlore
lattice. We show that there are pinch point features in the scattering intensity. The dominant coupling in this system is the long-range magnetostatic dipolar interaction, whose singularity at the zone center is passed onto the scattering intensity. However, the pinch points survive when the range of the dipoles is truncated to finite shell number in the form of a three-band quadratic band touching protected by cubic
symmetry. This model, which is related to the Luttinger semi-metal, provides a general long wavelength model for the emergence of pinch point scattering intensity encompassing also the true long-range dipolar model.
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All authors Olivier Demortier, Françoise Damay, Paul McClarty, Stéphane Raymond, Jacques Ollivier, Sylvain Petit
Materials Science
A Community-Developed Domain Ontology for Magnetic Materials
Wilfried Hortschitz, Santa Pile, Claas Fillies et al. (+18 more)
Magnetic materials play a crucial role in energy-related technologies, mobility, and sensing, but their complex multiscale behaviour and the coexistence of multiple unit systems pose persistent challenges for data exchange and interpretation. This paper presents a domain ontology for
magnetic materials, developed within the European Union funded
Magnetic Multiscale Modelling Suite (MaMMoS) project and aligned with the Elementary Multiperspective Material Ontology (EMMO). The ontology formalises intrinsic, hysteretic, and microstructural properties across multiple length scales and supports semantic interoperability between simulation tools, databases, and experimental workflows. One key feature of the ontology is its code-based and human-readable structure, enabled through the EMMOntoPy framework, which allows for direct manipulation and versioning without relying on opaque .owl or .ttl files. This facilitates collaborative development and improves transparency. The ontology supports FAIR (Findable, Accessible, Interoperable, Reusable) principles and is openly available for extension by the community. The aim of the MaMMoS project is to foster reproducibility, improve traceability, and promote the adoption of ontology in the magnetism domain. The ontology that has been developed already serves as the foundation for multiple software tools that handle all kinds of
magnetic material data.
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All authors Wilfried Hortschitz, Santa Pile, Claas Fillies, Harald Oezelt, Alexander Kovacs, Hans Fangohr, Samuel J. R. Holt, Martin Lang, Andrea Petrocchi, Swapneel Pathak, Michael P. Adams, Jonas Winkler, Thomas G. Woodcock, William Rigaut, Pierre Le Berre, Nora M. Dempsey, Alena Vishina, M. Nur Hasan, Georgia A. Marchant, Heike C. Herper, Thomas Schrefl
Materials Science
Bottom-up Synthesis of Metastable 2D Hexagonal Copper(I) Iodide on Monolayer and within Bilayer Graphene
David Kaiser, Guobin Jia, Janis Köster et al. (+9 more)
Copper(I) iodide (CuI) is a wide-bandgap
semiconductor crystallizing in the 3D $\gamma$-phase under ambient conditions; its layered van der Waals bulk phase $\beta$-CuI is stable only between 643 and 673 K. The two-dimensional (2D) h-CuI form has been obtained via
liquid-phase exfoliation of mechanochemically prepared precursors and via encapsulation between
graphene sheets, whereas bottom-up growth of 2D h-CuI on open surfaces has not yet been demonstrated. Here, we report a vapor-phase synthesis of h-CuI directly on low-defect, large-area monolayer and within bilayer reduced oxo-
graphene (r-oxo-G) at low temperatures. Using a copper TEM grid as the solid-state precursor for copper, HI-vapor exposure at 40 $\deg$C initiates nucleation, while annealing at 180 $\deg$C promotes the growth of extended h-CuI domains. Aberration-corrected HRTEM resolves the atomic structure, local twist angles, and
lattice anisotropy of the CuI/r-oxo-G nanohybrid, while STEM-EDX yields a Cu:I ratio consistent with 1:1. First-principles calculations show that van der Waals adhesion to
graphene stabilizes the supported hexagonal layer. Under the presented low-temperature precursor conditions, pathways for nucleation of the $\gamma$-phase are not available, allowing the hexagonal phase to form selectively at the
graphene interface. Ab initio molecular dynamics simulations show that the
heterostructure retains its hexagonal
lattice order at 600 K, including on an open monolayer
graphene support. The lateral extent of the growth is limited mainly by remaining interfacial adsorbates. These results establish a route to metastable 2D h-CuI on a chemically inert
graphene template, which may be useful for wide-bandgap electronic and optoelectronic devices.
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All authors David Kaiser, Guobin Jia, Janis Köster, Sadegh Ghaderzadeh, Christian E. Halbig, Siegfried Eigler, Andrey Turchanin, Benjamin Dietzek-Ivanšić, Arkady V. Krasheninnikov, Jonathan Plentz, Elena Besley, Ute Kaiser
Statistical Mechanics · Cross-listed from quant-ph
Local decoders for fault-tolerant quantum computation and translation-invariant stabilizer codes
Nathaniel Selub, Aditya Bhardwaj and Ethan Lake
We construct the first fully spatially local fault-tolerant
quantum computer based on topological codes in fewer than four spatial dimensions. Our construction is a two-dimensional architecture that uses only geometrically local
quantum and classical operations, bounded-speed classical communication and computation, and a constant density of
quantum and classical resources. The core component is a new time-translation-invariant cellular-automaton decoder for the surface code. This decoder preserves logical information for a time stretched-exponential in the code distance and operates continuously during state injection, stabilizer-state preparation,
lattice surgery, and transversal readout. We also prove that every translation-invariant topological Pauli stabilizer code is locally decodable under phenomenological noise.
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Materials Science
Vacancy Order and Physical Properties of a Ternary Compound Fe0.68Pd0.80Te with an {\alpha}-Fe1+xTe-Type Structure
Bingxian Shi, Manyu Wang, Chenglin Shang et al. (+14 more)
We report the identification and characterization of a new compound Fe0.68Pd0.80Te with an {\alpha}-Fe1+xTe prototype structure. Different from the Fe-square net and minor occupancy of interstitial Fe-sites in Fe1+xTe, Fe0.68Pd0.80Te is featured by a Pdsquare net and near 68% occupancy of the corresponding interstitial Fe-sites. Furthermore, noncontact atomic force microscopy and X-ray diffraction provide evidence for the existence of a 3*3*3 Pd-vacancy order in this layered material. A
spin-glass ground state below Tg 40 K is identified via
magnetic characterization. Electrical transport measurements show that Fe0.68Pd0.80Te is a
semiconductor with a very small band gap below 10 meV. It has weak negative magnetoresistance and holelike charge carriers below room temperature. Our results demonstrate its potentials for further exploring various
quantum phenomena.
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All authors Bingxian Shi, Manyu Wang, Chenglin Shang, Yanyan Geng, Yangyang Fan, Xiaoxiao Pei, Li Huang, Daye Xu, Juanjuan Liu, Jinchen Wang, Hongxia Zhang, Hongliang Wang, Lijie Hao, Rui Xu, Zhongyi Lu, Zhihai Cheng, Peng Cheng
Materials Science
Anisotropy of Ultrafast Strain in $V_2O_3$ Thin Films: Out-of-Equilibrium Phase Transitions under Interfacial Clamping
J. Guzman-Brambila, R. Mandal, D. Lea et al. (+9 more)
Ultrafast photoinduced
insulator-to-metal transitions in correlated materials are often mediated by
lattice distortions, yet the role of interfacial
lattice constraints in shaping nonequilibrium pathways remains largely unexplored. We use azimuth-resolved time-resolved X-ray diffraction to track orientation-dependent strain dynamics in granular V$_2$O$_3$ thin films on c-cut sapphire, where thermal-expansion mismatch imposes anisotropic interfacial strain. Across the thermal transition, the azimuthal profile of the (110)$_H$ strain inverts
curvature, providing direct evidence of partial clamping of the hexagonal basal-plane
lattice (a$_H$,b$_H$). After photoexcitation of the antiferromagnetic insulating phase, the structural response remains clamp-limited: weakly constrained grain families reach the full basal-plane contraction characteristic of the metallic-like state, whereas strongly constrained families exhibit a strongly reduced distortion. Fluence-dependent measurements further disentangle transformed fraction from clamping-limited
lattice distortion. Our results show that interfacial clamping acts as a static selector for ultrafast phase switching and provide a general route to quantify anisotropic strain dynamics in
heterostructures.
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All authors J. Guzman-Brambila, R. Mandal, D. Lea, E. Trzop, M. Servol, J. C. Ekström, F. Pawula, J. Tranchant, L. Cario, M. Lorenc, E. Janod, C. Mariette
Strongly Correlated Electrons · Cross-listed from hep-th
Gauss Law, Monodromy Defect, Magnetic Lattice Translation, and Lattice Duality
Pengcheng Wei and Yunqin Zheng
In a
Hamiltonian lattice gauge theory, the physical
Hilbert space is fixed by the Gauss law, by choosing an eigenspace of the Gauss law operator which generates the gauge transformation. Choosing a non-trivial eigenspace is referred to as the modified Gauss law. In 2+1d dynamical U(1) pure gauge theory, we show that these physical
Hilbert spaces are defect
Hilbert spaces associated with non-topological monodromy defects for monopole operators and topological defects for U(1) 1-form
symmetry, inserted along the time direction. We also construct the corresponding
lattice translation operators. Under a nontrivially modified Gauss law, these translations obey a
magnetic translation
algebra. Finally, we discuss how the modified Gauss laws are manifested in 2+1d compact
bosons, via exact duality on the
lattice.
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Statistical Mechanics
Rare-History Transitions in Temporally Random Integrable Quantum Circuits
Tingfei Li and Jie Gu
We study current fluctuations in a temporally random integrable
quantum circuit. Commutativity reduces every drive history exactly to its layer composition, turning annealed fluctuations into a competition between current gain and the large-deviation cost of rare compositions. For each fixed composition, homogeneous thermodynamic Bethe ansatz dressing supplemented by ballistic fluctuation theory yields the conditional current statistics. Their annealed large-deviation contraction predicts a first-order switch between two dominant history classes, terminating on a line of regular cusp endpoints. Finite-time analysis shows how the switch is rounded. Thus temporal randomness can act as an emergent order-parameter-like coordinate in trajectory space.
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Strongly Correlated Electrons
Instabilities in self-consistent diagrammatic approaches and how to cure them
Marcel Gievers, Herbert Eßl, Stefan Rohshap et al. (+2 more)
While self-consistent diagrammatic approaches are widely used to compute the physical properties of correlated
quantum materials, their applicability may get severely hindered precisely in the parameter regions where the most exciting physics is observed. One of the major issues, referred to as "misleading convergence", is the tendency of iterative schemes to converge to unphysical fixed points for intermediate-to-strong electronic interactions, regardless of the numerical accuracy of the computation. Here, we explicitly verify that the origin of this problem in several established self-consistent many-electron approaches, defined in the general diagrammatic framework of the
boson-exchange formalism, resides exclusively in the stability condition of the respective iteration schemes, and not in an intrinsic breakdown of their self-consistent diagrammatic description. This insight enables a simple and general remedy, as recently proposed in Phys. Rev. Lett. 137, 016502 (2026): The redefinition of the iterative procedure, by inverting the unstable eigendirections of the Jacobian associated with the fixed point of the self-consistent
algorithm. We illustrate the successful outcome of this procedure by means of systematic calculations performed on exactly solvable testbed models. Our results demonstrate that the physical fixed point of the diagrammatic schemes we considered can be stabilized, de facto, across the entire parameter range, including the most challenging nonperturbative/strong-coupling regimes.
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All authors Marcel Gievers, Herbert Eßl, Stefan Rohshap, Anna Kauch, Alessandro Toschi
Mesoscale and Nanoscale Physics · Cross-listed from physics.app-ph
Influence of magnetic fields on the performance of spin-orbit torque magnetic random-access memory
Jiaxin Liu, Yuqing Zhou, Guoyi Shi et al. (+1 more)
Spin-orbit torque
magnetic random-access
memory (SOT-MRAM) offers high speed, ultrahigh endurance, and compatibility with advanced
semiconductor processes, making it a promising candidate for next-generation nonvolatile
memory. However, intrinsic bias fields in
magnetic tunnel junctions (MTJs), originating from reference-layer stray fields and interlayer coupling, cause asymmetric critical switching currents and increased energy consumption. Existing compensation approaches usually introduce additional
magnetic layers into the MTJ stack, which increases fabrication complexity and limits wafer-scale integration. Here, we propose a bias-compensation strategy without modifying the MTJ stack by engineering local stray
magnetic fields through
magnetic filling materials in vertical interconnect access (VIA) channels during the back-end-of-line process. Micromagnetic simulations show that the proposed
magnetic filling layer can provide the required auxiliary field for deterministic switching and significantly suppress write-current asymmetry. By optimizing the MTJ position relative to the
magnetic filling structure, the write-current bias ratio is reduced from 21.6% in the conventional design to 1.3%. The approach is also applicable to in-plane
magnetic anisotropy SOT-MTJs, reducing the bias ratio from 19.8% to -0.2%. Scaling analysis further demonstrates that the compensation effect remains effective when the device size is reduced to 20% of the original dimension (MTJ diameter approximately 10 nm), indicating its potential for high-density SOT-MRAM integration.
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All authors Jiaxin Liu, Yuqing Zhou, Guoyi Shi, Kaiming Cai
Quantum Gases
Microwave-controlled interactions and stripe formation of static-field-shielded polar molecules
Tiziano Arnone Cardinale, Malte Schubert and Stephanie M. Reimann
We study polar molecules where short-range losses are suppressed by a shielding scheme involving a static electric field and an elliptically polarized microwave field. Using perturbation theory, we derive the effective interaction potential and validate it against coupled channel calculations. We identify a parameter regime where two-body losses are strongly suppressed and the extended mean-field description of dilute molecular Bose-Einstein condensates is justified. We calculate the collective excitations and show that intriguingly, supersolidity in quasi-two-dimensional confinement emerges as a stripe phase even at small values of microwave ellipticity.
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Statistical Mechanics
Disordered ground states in one-dimensional exactly solvable fluids
Igor Travěnec and Ladislav Šamaj
One-dimensional fluids of classical hard-core particles of diameter $a$, interacting in pairs via a soft repulsive (monotonically decreasing) potential of finite range $\varphi(x)=\varepsilon \left[ (a'-x)/(a'-a)\right]^{1/\nu}$ $(a\le x\le a')$ with real positive parameters $\varepsilon$ and $\nu$, are studied in an isothermal-isobaric ensemble. If $a'\le 2a$, the pairwise interactions are reduced to nearest-neighbour interactions, which allows for an exact solution of the thermal
equilibrium. We focus on the $T\to 0$ ground states, specifically on the equation of state for the mean distance between nearest neighbours $l_0$ and the pair correlation function $g_0(x)$. If $\varphi(x)$ is concave $(\nu\ge 1)$, there exists an “incompressibility” pressure $p_i=\varepsilon/(a'-a)$ such that the ground state is an equidistant chain of particles with spacing $l_0=a'$ for $0<p<p_i$ and with spacing $l_0=a$ for $p>p_i$. If $\nu>1$ (strict concavity), the ground state at $p=p_i$ is disordered with $l_0=\left[ \nu a +(\nu-1)a'\right]/(2\nu-1)$ and $g_0(x)$ being a superposition of weighted Dirac delta functions over discrete positions. If $\nu=1$ (linear ramp), the ground state at $p=p_i$ is disordered with $l_0=(a+a')/2$ and the continuous $g_0(x)$ is a superposition of Heaviside step functions multiplied by
polynomials in $x$. The isothermal susceptibility at $T=0$ is nonzero for concave $\varphi(x)$ ($\nu\ge 1$) at $p=p_i$ and, therefore, the corresponding disordered ground states are non-hyperuniform, i.e., they resemble disordered fluids at nonzero temperatures. It turns out that pair correlation functions of disordered ground states, which occur only at a single pressure $p_i$, extend their predictive power to thermodynamic states at nonzero temperatures over a wider range of pressures around $p_i$.
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Statistical Mechanics
Orientational order on non-orientable domains
Gianmarco Spera, Axel Fotso Ndefo, Keaton J. Burns et al. (+1 more)
We study the statistical properties of passive and active many-body systems with orientational degrees of freedom on non-orientable domains. By rephrasing topological constraints as non-local
symmetry relations on an orientable double-cover, we show that non-orientability eliminates global rotational soft modes without acting like an external field. In a passive XY model, this results in topological caging, where orientational fluctuations that exhibit conventional diffusive behavior on a
torus saturate on a Klein bottle to a finite value that we compute exactly in the thermodynamic limit. In models of active self-propelled particles with orientational degrees of freedom, topological caging persists despite continuously changing interaction neighborhoods. In an active Ising
spin model, non-orientability enforces the coexistence of ordered anti-parallel domains with vanishing global polar order, a state that is absent on orientable domains.
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All authors Gianmarco Spera, Axel Fotso Ndefo, Keaton J. Burns, Alexander Mietke
Materials Science
Correlation enhanced altermagnetism mediated by spin-lattice coupling in CrSb
Charmi Bhalani and Banasree Sadhukhan
Altermagnets (AMs) exhibit momentum-dependent
spin splitting without net magnetization, making them promising platforms for spintronic applications. While the
symmetry and multipolar origins of nonrelativistic altermagnetic
spin splitting (NRASS) are well established, the role of electronic correlations and
spin-
lattice coupling (SLC) in controlling NRASS remain unexplored. In particular, SLC provides a direct pathway for tuning altermagnetism through
lattice degrees of freedom. Here we first investigate the role of electronic correlations on altermagnetic strength in NiAs-type material CrSb using density functional theory (DFT), DFT+$U$, and dynamical mean-field theory (DMFT). We find that increasing electronic correlations substantially enhance NRASS and drive the stabilization of an incommensurate
spin-spiral (SS) state, while dynamical correlations further amplify the
spin splitting through quasiparticle renormalization of the Cr-$3d$ states. We find that the NRASS remains 12.5% larger in DFT+DMFT than in DFT. By evaluating SLC in next step, we establish its direct connection to the
evolution of NRASS and identify SLC as a microscopic descriptor between electronic correlation and enhanced altermagnetism in CrSb. Investigating it in another NiAs-type compound MnTe, we show that the SLC-NRASS correlation is generic across AMs and establish SLC as a microscopic descriptor of altermagnetic strength. Our results provide a unified framework for tuning altermagnetism through the interplay between the electronic correlations and
lattice degrees of freedom.
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