Chiral magnetic textures, such as skyrmions, are of great interest to the condensed matter community due to their novel transport properties. The stabilization of topologically nontrivial magnetic phases, like the skyrmion lattice in cubic MnSi, is governed by underlying magnetic interactions which can be probed via measurements of spin-wave excitations. Here, we report high-resolution inelastic neutron scattering (INS) measurements of the spin waves in Fe-doped ${\mathrm{Mn}}_{0.9}{\mathrm{Fe}}_{0.1}\mathrm{Si}$ deep within its field-polarized ferromagnetic state. We observe nonreciprocal spin waves with a parabolic dispersion that shifts linearly with magnetic field. Crucially, the spin-wave stiffness is highly anisotropic, with values of 17.2(5) meV ${\text{Å}}^2$ parallel to the applied field and 9.3(3) meV ${\text{Å}}^2$ perpendicular to it. While the applied field fundamentally lowers the systems symmetry from cubic to uniaxial, we demonstrate that the induced spin-wave anisotropy is significantly large, which is not captured within the simple theoretical approximations widely applied up to date.

We analyze the dielectric response of superlattice samples composed of titanate phases: calcium titanate, strontium titanate, and barium titanate, stacked at the ultimate atomic layer limit to break inversion symmetry. High temperature susceptibility measurements extracted from low-frequency ($\sim 100\mathrm{Hz}$) ac capacitance measurements indicate that the asymmetric strain field provides an effective polarizing field that polarizes the samples even at high temperature with the sign of the polarization consistent with the sign of the stacking asymmetry. From the combined temperature, frequency, and electric field dependence, we provide evidence that the size of the dynamically coherent dipole units that persist at high temperatures has little variability from sample to sample and have a volume of $\sim 10$ perovskite unit cells. As temperature is lowered, below a crossover temperature $T_{xy}$ the dielectric response deviates from that expected of activated reorientation of two-state switchable dipoles governed by kinetics. This deviation points to the further growth of dynamically coherent dipole units. Pyrocurrent and dc transient current measurements indicate an unusual asymmetric hysteretic response at low temperatures with a temperature-dependent shift of the $P\left(E\right)$ loops resulting in a low temperature offset polarization. We argue that the responding dipole units above $T_{xy}$ are correlated only along the superlattice stacking direction by the built-in strain field resulting in nanopillars of single unit cell cross-sectional areas. The growth of the dynamically coherent dipole units below $T_{xy}$ points to the emergence of lateral correlations and an unusual ferroelectric response is observed subject to the built-in asymmetric strain field.

Charge-density waves (CDWs) are a hallmark of collective electronic ordering. As the pioneering and most fundamental model system studied in CDW physics, one-dimensional (1D) CDWs are theoretically profound yet experimentally fragile. They are widely recognized to be highly susceptible to environmental screening and surrounding lattice bonding. As a result, robust and stable CDWs have thus far been predominantly realized in nearly isolated 1D systems. Here, we demonstrate that robust 1D CDWs can emerge even when the 1D systems are embedded in a two-dimensional metallic environment. Using scanning tunneling microscopy and spectroscopy, we observe clear CDW signatures, including periodic charge modulation and pseudogap formation near the Fermi level, in multiple distinct 1D nanostructures formed in $1T^{\prime }$-phase ${\mathrm{MoTe}}_2$. Our first-principles calculations reproduce the main experimental results, providing strong support for the CDW origin. The consistent observation of these key features across different structural motifs provides unambiguous evidence that CDW order can be robustly stabilized in quasi-1D systems, despite the presence of strong metallic screening and significant surrounding lattice bonding.

Carbon nanotubes (CNTs) constitute a highly tunable platform for probing the interplay between structural chirality and quantum transport in quasi-one-dimensional systems. Here, we perform a systematic study of the nonequilibrium orbital response across a broad set of metallic and semiconducting chiral CNTs. We find that the orbital Edelstein susceptibility depends strongly on both chirality and nanotube diameter, revealing that the orbital response cannot be captured by a universal scaling law. Instead, distinct families of CNTs emerge, forming characteristic orbital-response branches uniquely determined by the chiral wrapping vector. We further investigate the role of metallic contacts on orbital-current generation and orbital selectivity. While metallic CNTs rapidly recover their intrinsic orbital response away from the contact region, semiconducting CNTs display pronounced oscillatory behavior arising from interference between transport channels carrying different angular momenta injected by wide-band metallic contacts. Finally, by incorporating angular correlations into the contact self-energy, we demonstrate that chiral CNTs can operate as efficient orbital angular momentum filters, selectively transmitting orbitally textured electronic states in accordance with the crystal angular momentum of the propagating bands.

Strongly correlated fermionic systems are of great interest in condensed matter physics and numerical methods are indispensable tools for their study. However, existing approaches such as exact diagonalization (ED) and stochastic quantum Monte Carlo methods each suffer from fundamental limitations: ED is hindered by exponential scaling in system size, while Monte Carlo methods are plagued by sign problems and long autocorrelation times. These limitations restrict the accessible parameter space and developing algorithms that efficiently alleviate them remains a central challenge in computational physics. In this work, we propose a hybrid algorithm that combines ED and Hamiltonian Monte Carlo (HMC) to simulate two-dimensional (2D) arrays of coupled quantum wires, modeled as interacting fermionic Hubbard chains. We demonstrate how our hybrid implementation of HMC, which we dub ${\mathrm{H}}^2\mathrm{MC}$, outperforms either method alone across several key simulation facets. When compared to pure ED, ${\mathrm{H}}^2\mathrm{MC}$ has a much more favorable computational scaling, which allows us to push simulations to much larger 2D arrays. ${\mathrm{H}}^2\mathrm{MC}$ also greatly alleviates the sign problem and reduces autocorrelation times when compared to pure HMC formulations utilizing either real or imaginary auxiliary fields. Our formalism demonstrates how complementary strengths of seemingly disparate methods can be leveraged to enable feasible simulations in an extended parameter space.

Hall viscosity is a quantized nondissipative stress response of a fractional quantum Hall (FQH) fluid to adiabatic geometric deformations. Despite strong theoretical interest, its experimental observation in the FQH state has remained elusive, making it a demanding target for realization on current IBM quantum hardware. In this letter, we employ a quasi-one-dimensional model of an FQH state coupled to a background metric to probe the geometric response under a metric quench. We design and implement a quantum-circuit protocol that realizes a Hilbert-space-truncated version of the model and extracts the Hall viscosity from the geometric response encoded in the wave-function dynamics on the IBM quantum hardware. While the truncation prevents us from accessing the fully quantized value of Hall viscosity, the hardware data closely track analytical and numerical predictions within this regime.

In this study we present a detailed spectroscopic analysis of the optical gain in a ZnO/ZnMgO waveguide microcavity benchmarked with a thick homoepitaxial ZnO layer. As a prerequisite we perform a precise determination of ZnO excitonic parameters through microreflectivity and low-excitation microphotoluminescence measurements, whose results are used as inputs for the optical gain analysis. While photoluminescence spectra and their dependence on excitation intensity reveal the presence of biexcitons in the ZnO samples, they do not participate in building up optical gain. Instead, three alternative physical processes need to be taken into account to explain optical gain in ZnO: inelastic exciton-exciton scattering; an intermediate regime involving preformed, weak-bond electron-hole Cooper pairs; and an electron-hole plasma at high carrier density. Within the current low quality factor in-plane cavity, our results are consistent with an optical gain at moderate particle densities sustained by a correlated electron-hole phase with preformed electron-hole Cooper pairs. This phase evolves to an electron-hole plasma at larger densities.

We present a rigorous method to reduce the three-dimensional (3D) description of a quantum dot in silicon to an effective two-dimensional (2D) envelope function theory for electron spin qubits. By systematically integrating out the strongly confined vertical dimension using a Born–Oppenheimer-inspired ansatz at the envelope-function level, we derive an effective in-plane potential that faithfully captures the essential electrostatics of the full 3D system. Considering the lowest two eigenstates of the out-of-plane direction, this reduction leads to the natural and explicit emergence of the valley degree of freedom within a 2D formalism, which is derived here from first principles. We validate the accuracy of the method through comparisons with full 3D simulations and demonstrate its superiority over naive 2D slicing, particularly in the presence of interface roughness. Crucially, the reduction in dimensionality leads to substantial computational savings, making our approach particularly well suited for simulating two-electron systems, e.g., for the extraction of parameters such as the exchange coupling. Beyond its practical utility, the rigorous 2D envelope function theory that is introduced in this study incorporates valley physics in a physically grounded manner, offering conceptual clarity on the role of valley states in qubit operation and measurement.

Recent experimental and theoretical studies have revealed the emergence of a linear layer Hall effect (LHE) induced by hidden Berry curvature in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ thin films. This phenomenon underscores the layer degree of freedom as a mechanism for generating Hall transport in layered materials. In this work, we predict a hidden Berry curvature dipole (BCD) in $\mathcal{PT}$-symmetric layered antiferromagnets (AFMs), which manifests as a nonlinear LHE that is even with respect to the AFM order and odd with respect to the vertical electric field, in contrast to the linear LHE. The coexistence of both the hidden BCD and quantum metric dipole (QMD) interprets an asymmetric lineshape with respect to a vertical electric field $E_z$ as observed in recent experiments. Furthermore, we demonstrate that the nonlinear Hall currents induced by the hidden BCD and QMD obey distinct symmetries and flow in different directions, which can be conveniently distinguished through the nonlinear anomalous Hall conductivity. Our proposed nonlinear LHE establishes an experimentally advantageous framework for exclusively probing the hidden BCD quantum geometry.

Magnetic vortices, magnetic textures characterized by their winding numbers of the in-plane magnetization component, hold considerable importance in both fundamental and applied physics. In perpendicularly magnetized disks, transient vortex excitations can be viewed as twisted spin waves, and it is generally considered that their winding numbers should be stable against time evolution. Here, however, we show that this is not the case in systems with discrete rotational symmetry, where a modular transmutation rule applies to the central winding number. We show that such a symmetry breaking can be induced by azimuthal modulation of material parameters in the disk. This work not only advances our understanding of transient vortex excitations, but also establishes symmetry as a novel degree of freedom for manipulating magnetic textures.

We investigate the interplay between photomagnetism and spin-glass freezing in CoFe Prussian blue analogues through controlled reacting time and dynamic magnetic analysis. Reacting time continuously modifies the internal CN-bridged pair populations while keeping the average Fe-vacancy concentration low, thereby providing a route to tune the magnetic exchange network without introducing significant additional defect disorder. Fourier-transform infrared measurements show that the fraction of ${\mathrm{Fe}}^{\mathrm{III}}\text{-CN-}{\mathrm{Co}}^{\mathrm{II}}$ pairs decreases systematically with reacting time, accompanied by an increase in ${\mathrm{Fe}}^{\mathrm{II}}\text{-CN-}{\mathrm{Co}}^{\mathrm{III}}$ pairs. Correspondingly, the ground-state ferrimagnetic response is progressively weakened, as reflected by reduced coercivity, lower high-field magnetization, and a downward shift of the Curie temperature. The spin-glass behavior is suppressed in parallel, with the freezing temperature shifting to lower values and the ac susceptibility peak eventually disappearing in aged samples. Despite this suppression, all samples retain a pronounced photomagnetic response under illumination. Light irradiation enhances the magnetization and coercivity and, more importantly, strengthens or even induces spin-glass freezing in samples with more reacting time. In the defect-poor sample, Mydosh analysis and Vogel-Fulcher fitting show that illumination increases the freezing temperature, the freezing-limit temperature $T_0$, and the activation energy $E_a$, indicating strengthened interaction-dominated freezing and a more stable glassy energy landscape. These results identify ${\mathrm{Fe}}^{\mathrm{III}}\text{-CN-}{\mathrm{Co}}^{\mathrm{II}}$ pairs as the key microscopic units linking photomagnetism to nonequilibrium spin freezing and demonstrate that reacting time and light act as two opposite control parameters on the same exchange network in CoFe Prussian blue analogues.

Several models of the strange-metal state of the cuprate superconductors postulate the existence of strong inelastic forward scattering of the electrons, but direct evidence of such scattering is missing. Here we show that angle-resolved photoemission spectroscopy (ARPES) provides a unique tool that can address this issue. We propose a two-lifetime phenomenological model of the superconducting state of the cuprates, and we show that it explains several salient low-energy features of the measured ARPES spectra. The model enables discrimination between forward- and large-angle scattering and, in addition, gives access to the magnitude of the gap function away from the Fermi surface.

We report an experimental study of the disordered Su-Schrieffer-Heeger (SSH) model, implemented in a system of coaxial cables, whose radio frequency properties map onto the SSH Hamiltonian. By measuring multiple chains with random hopping terms, we demonstrate the presence of a topologically protected state, with frequency variation of less than 0.2% over the ensemble, evidence of near-perfect chiral symmetry. When the ends of the chains are connected to form loops, we observe a topological phase transition, characterized by the closure of the band gap and the appearance of states that are delocalized, despite the strong disorder.

The prevalence of sparsity in the Fock space graph of interacting many-body systems motivates an investigation into the spectral statistics of sparse random matrices with on-site disorder. We numerically determine the delocalization-localization transition in the ground state as a function of the sparsity. The short-range energy correlation in the bulk indicates that the Anderson transition at infinite temperature occurs at the critical percolation limit of the sparse graph. By analytically deriving the energy moments and calculating the shifted kurtosis, we show that the critical sparsity threshold matches the Anderson transition. Furthermore, long-range energy correlations in the bulk spectrum reveal a Thouless energy scale, suggesting a broad nonergodic regime within the delocalized phase.

${\mathrm{RuO}}_2$, proposed as a potential altermagnet, is expected to serve as a new-generation spintronic material enabling precise control of spin transport. However, the existence of magnetic order in ${\mathrm{RuO}}_2$ has recently been widely questioned. Here, based on first-principles calculations, we systematically investigate the magnetic order in ${\mathrm{RuO}}_2$ under epitaxial strain. We find that a modest global strain can drive ${\mathrm{RuO}}_2$ from a nonmagnetic state to an antiferromagnetic state. Furthermore, near the strain-induced magnetic critical point, a modest local distortion can stabilize a spin-density-wave state over the antiferromagnetic state, with an energy difference on the order of $10-100\mu \text{eV}$ and a characteristic wavelength of about 7–10 nm. Our study provides a unified microscopic picture for the experimental controversy regarding altermagnetism in ${\mathrm{RuO}}_2$, and highlights the key roles of global strain and local distortion in tuning ${\mathrm{RuO}}_2$ magnetism and spin transport.

NaB(CN)${}_4$ exhibits giant negative thermal expansion (NTE) that is closely associated with low-frequency phonons with large negative Grüneisen parameters. Although compression-induced softening of negative-Grüneisen phonons can modify lattice thermal conductivity (${\kappa }_{\mathrm{L}}$), how NTE-active phonon modes differently influence the population (${\kappa }_{\mathrm{pop}}$) and coherence (${\kappa }_{\mathrm{coh}}$) contributions to ${\kappa }_{\mathrm{L}}$ remains unclear. Here, we combine perturbative high-order anharmonic lattice dynamics and homogeneous nonequilibrium molecular dynamics (HNEMD) simulations accelerated by a neuroevolution potential (NEP) to investigate compression-dependent thermal transport in NaB(CN)${}_4$. Both approaches capture a compression-induced decrease in ${\kappa }_{\mathrm{L}}$. At 300 K, NEP–HNEMD simulations show that ${\kappa }_{\mathrm{L}}$ decreases from $1.05\pm 0.03$ to $0.49\pm 0.01\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ over the structurally intact strain range examined up to $4\%$. In the weak-compression regime, the reduction is dominated by the suppression of ${\kappa }_{\mathrm{pop}}$. NTE-active framework modes near 2.5 THz soften under compression, reducing phonon group velocities and increasing the three-phonon scattering phase space. By contrast, the compression-induced difference in ${\kappa }_{\mathrm{coh}}$ is mainly concentrated near 7.5 THz, where the relevant phonon pairs harden. Nevertheless, ${\kappa }_{\mathrm{coh}}$ increases only slightly and remains secondary to ${\kappa }_{\mathrm{pop}}$. These contrasting responses reveal a nonuniform phonon-spectrum reconstruction under compression in which strain selectively reshapes the population and coherence channels of heat transport, linking NTE-active phonons to anomalous thermal transport in NaB(CN)${}_4$.

We solve the two-electron problem on a square lattice with $d$-wave altermagnetism, considering both on-site and nearest-neighbor attractive interactions. The altermagnetic spin-splitting in the single-particle dispersion naturally gives rise to a ground state of two-electron bound pairs with nonzero center-of-mass momentum. The emergence of finite-momentum bound states suggests that altermagnetic spin splitting may favor pairing at nonzero center-of-mass momentum, which could be relevant for proposed Fulde-Ferrell-Larkin-Ovchinnikov superconductivity in altermagnetic systems. Additionally, when the nearest-neighbor attraction is strong, the resulting finite-momentum bound pairs exhibit a mixture of both spin-singlet and spin-triplet characteristics, suggesting the possibility of unconventional superconductors, where spin-singlet and spin-triplet pairings coexist.

A central question beyond the Landau paradigm is the nonperturbative critical theory of the symmetric mass generation (SMG) transition, where strong interactions gap Dirac fermions in $2+1$ dimensions without triggering spontaneous symmetry breaking or topological order. Sign-problem-free studies have previously found fermion mass generation without bilinear condensation in related models, but the fermionic scaling properties of Hamiltonian SMG transitions remain incompletely characterized. Using sign-problem-free projector determinant quantum Monte Carlo simulations of a bilayer honeycomb lattice model with $\mathrm{SU}\left(2\right)\times \mathrm{SU}\left(2\right)\times \mathrm{SU}\left(2\right)/{\mathbb{Z}}_2$ symmetry and linear sizes up to $L=21$, we find evidence for a direct continuous transition: the single-particle and bosonic gaps open consistently near $J_c\approx 2.6$, with correlation-length exponent $\nu =1.14\left(2\right)$ from the better-converged fermionic analysis, while all 19 symmetry-inequivalent local fermion-bilinear multiplets remain disordered. We obtain an unbiased estimate of the fermion anomalous dimension, ${\eta }_{\psi }=0.071\left(1\right)$, which differs from the large-$N$ prediction (${\eta }_{\psi }\approx 0.595$) and the variational Monte Carlo estimate (${\eta }_{\psi }\approx 0.62$), thereby constraining candidate descriptions of SMG criticality. A comparison with a related $\mathrm{Spin}\left(5\right)\times \mathrm{U}\left(1\right)/{\mathbb{Z}}_2$ model, which develops an intermediate excitonic phase, illustrates how the symmetry content controls competing bilinear orders.