The cubic perovskite ${\mathrm{SrFeO}}_3$ is a prototypical centrosymmetric itinerant magnet that hosts a quadruple-$\mathbf{Q}$ hedgehog-antihedgehog lattice and exhibits a complex magnetic-field–temperature phase diagram. Yet, the microscopic mechanism underlying the emergence of its versatile multiple-$\mathbf{Q}$ phases remains unresolved. Here, we reveal the field-orientation dependence of the magnetic phase diagram and establish an effective spin Hamiltonian for ${\mathrm{SrFeO}}_3$ that incorporates a cubic single-ion anisotropy together with bilinear and biquadratic interactions in momentum space, which originate from the spin-charge coupling. In addition, we observe magnetoelastic signatures of a redistribution of the ligand-hole density upon entering the forced ferromagnetic phase. These findings are consistent with an important role of electronic itinerancy associated with the formation of a ligand-hole band in stabilizing multiple-$\mathbf{Q}$ phases.

Most materials with high thermal conductivity belong to one of two classes: metals, where heat is carried predominantly by electrons, and insulators, where heat transport is dominated by the phonon contribution. Materials that combine substantial electronic thermal conductivity and lattice thermal conductivity are rare, because the mechanisms that favor electron transport typically suppress phonon transport, and vice versa. Here, we report the theoretical prediction and experimental realization of such a material, metallic $\varepsilon$-TaN. Our calculations predict a total thermal conductivity at room temperature of $273\pm 5\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ in single crystals and $145\pm 5\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ in polycrystals with $0.5\mu \mathrm{m}$ grains, with an unusually large lattice contribution (79%) for a metal. The latter value is in agreement with our local transient thermoreflectance measurements on polycrystalline samples yielding $\sim 130\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$. We show that the balanced electronic and lattice thermal conductivities of $\varepsilon$-TaN originate from a combination of large Fermi velocity and small Fermi density of states on the electron side, and large speed of sound and wide phonon gap on the lattice side.

We predict the spin thermal Hall effect in nonreciprocal magneto-optical many-body systems, in which a longitudinal radiative heat current generates a transverse accumulation of the spin angular momentum carried by thermal photons. We show that this effect and the inverse spin thermal Hall effect constitute an Onsager-Casimir reciprocal pair, thereby establishing heat and photon spin as coupled transport channels in nonreciprocal photonic systems. The second law of thermodynamics imposes fundamental bounds on the spin-heat coupling, leading to a thermal-spin figure of merit that quantifies the efficiency of radiative spin-heat conversion. Our results establish a complete thermodynamic framework for photon-spin caloritronics and lay the conceptual foundations for spin-controlled thermal radiation and nonreciprocal photonic thermal devices.

Recently “the hat” monotile was introduced into the family of aperiodic tilings and quasicrystals boasting physical properties lying at the boundary of ordered and disordered systems. Here we study the two-dimensional wave transport, transverse localization, and scaling properties of the quantum modes in a monotile quasilattice. Our system is based on reconfigurable optical lattices for cavity polaritons which provide flexible means to study wave packet dynamics, strong nonlinear phenomena, and power-driven condensation in this new type of an aperiodic tiling. We confirm the existence of localized and critical states in the monotile through direct diagonalization of the Schrödinger equation. Scaling analysis on the moments of the wave-function distribution reveals anomalous transport regimes of superdiffusive and near subdiffusive polariton transport associated with the fractal structure of the monotile Hilbert space. We propose a strategy using resonantly excited polariton fluids to verify our findings.

Interaction between different two-dimensional materials can give rise to many exotic physical phenomena that are rarely observed in intrinsic materials. Recently, several theoretical and experimental works have revealed that magnetic proximity effect between pristine graphene and magnetic substrates can lead to the emergence of quantum anomalous Hall states and quantum spin Hall states. However, interplay between correlated states in graphene-based systems and magnetic materials has seldom been studied. Here, we perform the transport measurement at ultrahigh magnetic field of twisted double bilayer graphene (TDBG) on CrOCl (COC) substrate, which is an antiferromagnetic material. Instead of a magnetic-exchange effect on graphene, we observe an enhanced correlated insulating state at half-filling factor of TDBG as a result of the charge-transfer process between TDBG and COC. The temperature and magnetic-field dependence of this enhanced state are further studied. Our results demonstrate the influence of charge-related effect at the interface, and shed a light on a new route for manipulating the correlated states in graphene-based moiré systems using interfacial charge transfer process.

Quantum dot (QD)-superconductor hybrids have been established as a suitable platform for realizing Kitaev chains hosting Majorana bound states. Implementing these structures in a qubit architecture is expected to result in coherence times that scale exponentially with the lengths of the chains. To scale to longer systems, the phase differences between all superconducting segments in the chain need to be controlled. While this control has been demonstrated by using an external magnetic flux [ten Haaf et al., Nature (London) 641, 890 (2025); Bordin et al., Nat Commun 17, 2313 (2026)], ideally, it can be achieved with control over intrinsic system parameters [Liu et al., Phys. Rev. Res. 7, L012045 (2025)]. In this work, we investigate whether the relevant phase differences can be tuned through the spin degree of freedom in each QD or the chemical potential of the discrete bound states in the hybrid sections. We confirm that both these tuning knobs allow for controlling the phase difference in the couplings between neighboring QDs, bypassing the requirement to tune an external flux. However, we find that the amplitude of the phase shifts can deviate from a discrete $\pi$ shift. We introduce a spatial variation in the spin-orbit field as a possible mechanism to explain the observed behavior and comment on the consequences for experimentally creating long Kitaev chains.

It is established that the nonlinear anomalous Nernst effect (NANE), originating from Berry curvature near the Fermi energy, is symmetry-permitted only when the crystal symmetry in the transport plane of two-dimensional (2D) materials does not exceed a single mirror line. Here, we show that an applied direct electric field can lift this symmetry constraint, enabling an electric-field-induced NANE to emerge in time-reversal symmetric 2D systems with higher crystallographic symmetries. This electric-field-induced NANE originates from two contributions: the Berry connection polarization, which roots in the electric-field-corrected Berry curvature, and the anomalous-velocity-modified nonequilibrium Fermi distribution function. Additionally, we propose an alternating temperature gradient as a driving force instead of the conventional steady one, ensuring experimental detection of NANE via second-harmonic measurement techniques. The behavior of electric-field-induced NANE in the monolayer graphene has been theoretically and systematically investigated.

We investigate collective spin-wave excitations and curvature-driven instabilities in concentrically arranged nanotubes coupled via antiferromagnetic interlayer exchange. By solving the linearized Landau–Lifshitz equation including exchange, anisotropy, interlayer exchange coupling, and nonlocal dipolar interactions, we show that curvature substantially reshapes the spin-wave spectrum and the spatial structure of the eigenmodes. As the number of nanotubes increases, the spectrum evolves into a multiband structure with hybridized collective branches and surface-localized modes. In contrast to planar multilayers, the tubular geometry breaks the equivalence between inner and outer boundaries, producing asymmetric surface localization, curvature-induced shifts of the nodal structure, and nonreciprocal spin-wave propagation. We further analyze magnetic instabilities through the softening of the lowest spin-wave modes. For weak radial anisotropy, a uniform mode governs the instability, whereas above a critical anisotropy the soft mode occurs at a finite wave vector, signaling an instability toward a stripelike modulation along the nanotube axis. Although curvature shifts the instability thresholds, the characteristic modulation period remains nearly independent of the tube radius. The overall dynamical behavior of the coupled nanotubes can be understood in terms of an effective curvature-induced anisotropy, which unifies the spectral reconstruction and instability thresholds. These results establish tubular multilayers as a platform in which geometry controls both collective spin-wave excitations and instability-driven magnetic phases.

Superconductor–semiconductor coupling in hybrid nanowires plays a pivotal role in Majorana devices. Here, we demonstrate this tunable coupling in PbTe–Pb nanowires and its impact on the induced gap and zero-bias peaks (ZBPs). In the strong-coupling regime, the device reveals a clean superconducting gap, where robust and nonrobust ZBPs are observed in distinct magnetic field ranges. Conversely, increasing the gate voltage drives the system toward the weak-coupling regime, where the gap becomes narrow and soft. Consequently, robust ZBPs disappear while nonrobust ones persist. Our results establish a direct link between tunable coupling and robust ZBPs, providing guidelines on engineering Majorana zero modes and topological qubits.

We construct spin-$\frac{3}{2}$ and spin-$\frac{7}{2}$ models on the square-octagon and checkerboard lattices that are exactly solvable with Majorana representations. They give rise to spin-liquid phases with full spin-rotation and lattice-translational symmetries but broken time-reversal symmetry. Although nonzero on elementary plaquettes, the net orbital magnetic moment is guaranteed to vanish as a result of point symmetries; due to the analogy to long-range ordered altermagnets, these types of phases were dubbed altermagnetic spin liquids in [Sobral et al., Phys. Rev. Res. 7, 023152 (2025)]. For the spin-$\frac{3}{2}$ model, we find that a $g$-wave altermagnetic spin liquid emerges as the unique ground state. In contrast, the spin-$\frac{7}{2}$ model exhibits a significantly richer phase diagram, involving different types of chiral spin liquids competing with a $d$-wave altermagnetic spin liquid. Finally, we identify and characterize the topological and nontopological excitations, illustrating the rich physics of altermagnetic spin liquids resulting from the interplay of nontrivial topological and symmetry aspects of this novel phase of matter.

A recent experiment [L. A. Cohen et al., Science 382, 542 (2023)] observed a robustly quantized $e^2/2h$ conductance in a quantum point contact between fractional quantum Hall edges (a quantum Hall transformer), which then vanishes at low temperature. While this behavior can be described by a boundary sine-Gordon (BSG) model derived from electron tunneling, the microscopic motivation for such strong tunneling is unclear. We use an alternative model based on sliding charge density waves and a density inhomogeneity to clarify the BSG description and calculate the conductance over the full range of transmission. Using a perturbative method and a matrix product state calculation, we draw a quantitative connection between the BSG model and the physical quantum Hall system.

Topological electronic phases, particularly nodal-ring structures, have emerged as a forefront theme in contemporary materials and physical sciences, yet their underlying physics remain elusive. Here, starting from the effective Hamiltonian, we employ fluctuation dissipation electrodynamics to show that the band-crossing topology intrinsic to nodal-ring eigenstates fundamentally reconstructs thermal radiation. These extended gapless electronic states critically modulate intraband excitation channels of thermal radiation, inducing a pronounced spectral blueshift and a suppression of radiative heat transfer. Furthermore, we further elucidate the temperature dependence of this topological radiative reconstruction, and we demonstrate that nodal-ring electronic states can constitute a versatile platform for radiative thermal management devices, including thermal switching, thermal rectification, and thermal stabilization.

Beyond their fundamental interest in exploring bosonic Dirac physics, Dirac magnons hold potential for the development of efficient spin-transport devices. Here, we demonstrate the experimental realization of gapped terahertz Dirac magnons in an epitaxial Co bilayer on Ru(0001) using spin-polarized electron spectroscopy. Supported by first-principles calculations, we show that although the substrate breaks sublattice symmetry, thereby opening a gap at the $\overline{K}$ points, the local valley topology is preserved. This is evidenced by a spectral weight redistribution, valley-centered curvature concentrations, and a nonzero local Berry phase. Our results establish the interface as a tuning parameter, paving the way for engineering Dirac magnons in a variety of simple ultrathin bilayer magnets.

$\gamma \text{−}{\mathrm{Ba}}_3{\mathrm{CoNb}}_2{\mathrm{O}}_9$ realizes a disordered simple-cubic spin-$1/2$ lattice in which ${\mathrm{Co}}^{2+}$ ions randomly occupy one-third of the sites, placing the system just above the site-percolation threshold for magnetic order. Specific-heat, susceptibility, neutron spin-echo, and muon spin-rotation measurements reveal a broad thermodynamic crossover, short-range magnetic correlations, and persistent fast spin dynamics down to at least 0.1 K, with no evidence for static order or conventional spin-glass freezing within the experimental time windows. Monte Carlo simulations yield a broad distribution of orphan spins, finite clusters, and an infinite network. The weakly correlated spin fraction ($\approx 8.2\%$) inferred phenomenologically from magnetization is consistent with the calculated orphan-spin fraction ($\approx 8.8\%$). Exact diagonalization of a diluted $S=1/2$ Heisenberg model captures the broad magnetic specific-heat anomaly and supports the coexistence of weakly and strongly correlated spin environments. These results support a picture in which spin-$1/2$ quantum fluctuations, together with dilution and proximity to the percolation threshold, can support a disorder-driven dynamical state with short-range correlations in three dimensions, distinct from both classical spin glasses and geometrically frustrated quantum spin liquids.

The zero-field and applied-field Hall effects in noncollinear antiferromagnets provide evidence for topological states of matter and are tied to the magnetic symmetry of materials. For ${\mathrm{UNi}}_4\mathrm{B}$, the antiferromagnetic state with $T_{\mathrm{N}}=20$ K at zero and low magnetic field is being debated due to recent magnetoelectric measurements and theoretical work calling into question the proposed toroidal arrangement of magnetic dipole moments. For a magnetic field applied within the plane of uranium magnetic moments, the field-dependent Hall resistivity of ${\mathrm{UNi}}_4\mathrm{B}$ shows a curved response for ${\rho }_{yz}$ ($H\parallel x, I\parallel z$) and ${\rho }_{zx}$ ($H\parallel y, I\parallel x$) up to $\sim$8 T at 2 K, while an out-of-plane field results in linear behavior of ${\rho }_{yx}$ ($H\parallel z, I\parallel x$) up to 16 T. Analysis using conventional empirical relationships for the Hall effect indicates that an intrinsic effect from momentum-space Berry curvature contributes significantly to the curved transverse resistivity. Moreover, a finite zero-field Hall effect emerges at the onset of magnetic order for ${\rho }_{yz}$ and ${\rho }_{zx}$, further supporting an intrinsic origin of the Hall response. Symmetry arguments for a finite Berry curvature, an observable magnetoelectric effect, and reported magnetic structures suggest that the previously proposed magnetic space groups for the zero-field magnetic structure cannot account for the observed finite zero-field effect for two Hall orientations. Instead, we propose that $C{m}^{\prime }$ or $P{m}^{\prime }$ magnetic symmetry, depending on the parent nonmagnetic space group, is consistent with Hall resistivity, neutron diffraction, and magnetoelectric effect measurements.

We study the interplay between long-range electron-phonon and electron-electron interactions in electrostatically doped two-dimensional semiconductors, including interlayer couplings in van der Waals heterostructures. We evaluate the effects of those interactions on transport properties by writing dynamically coupled Boltzmann equations for the electrons and for the electrodynamically active excitations. We develop a theory with a general validity and apply it both to simplified parabolic models and to the realistic BN-encapsulated graphene system which we present in an accompanying paper [Dinar et al., Phys. Rev. Lett. 137, 176302 (2026)]. We show that dynamical screening effects are of fundamental importance to correctly describe the electronic transport properties of two-dimensional materials and, in particular, the scattering from polar phonons, whether those come from the semiconductor itself or the surrounding layers.

We present a systematic first-principles study of the spin-orbit torques in the ferromagnetic monolayers ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$ (FGT) and ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ (FGaT). Despite sharing the same crystal structure (point group $D_{3h}$) and predominantly Fe $3d$ spin-polarized bands, the two materials exhibit markedly different current-induced torques. We reveal these differences by computing the full angular dependence of the torkance—the torque per unit applied electric field—using linear-response theory with symmetry-adapted spin-orbit-coupled Wannier functions. FGaT may be viewed as a hole-doped analog of FGT, since Ga contributes one valence electron fewer than Ge. Although the work functions differ by only about 28 meV, the band filling near $K$ and $K^{\prime }$ changes substantially: The density of states at ${\varepsilon }_F$ is reduced by a factor of 3 and its spin polarization reverses from minority in FGT to majority in FGaT. These electronic changes are reflected in the torques resolved by time-reversal parity, sublattice, and momentum. In particular, we identify pronounced hidden torques in FGaT and relate the suppression of its fourth-harmonic Fermi-sea component to the evolution of momentum-space pockets. Finally, we discuss the emergence of such self-torques, which are not captured by the conventional picture of current-induced spin accumulation, within a symmetry-based phenomenological framework. Our results provide microscopic insight into current-induced torques in two-dimensional ferromagnets and offer guidance for defect and van der Waals engineering of layered magnetic materials.

Cavity materials engineering, aiming to manipulate material properties by coupling to vacuum fluctuations inside a cavity, is a rapidly advancing field. Despite significant progress, most studies to date have focused on specific materials and cavity configurations. Here, through a comprehensive group-theoretical analysis, we establish general symmetry rules for cavity materials engineering with linearly polarized cavity photon modes. By analyzing the symmetry of the Pauli-Fierz Hamiltonian within the long-wavelength approximation, we provide a classification of the symmetry-breaking patterns induced by cavity modes for all crystallographic point groups. The power of this framework is then demonstrated by quantum-electrodynamical density functional theory calculations. In particular, we explain the distinct cavity-induced lifting of band degeneracies in cubic ${\mathrm{BaTiO}}_3$ for different cavity mode configurations, and the cavity-modified infrared and Raman spectra of monolayer ${\mathrm{MoS}}_2$ due to symmetry breaking. Our results highlight the central role of symmetry in cavity materials engineering and provide general guidelines for future studies in this field.

We investigate a minimal molecular model consisting of square planar plaquettes hosting multiple electrons, whose dynamics is governed by a tight-binding Hamiltonian supplemented by on-site Hubbard repulsion. By coupling this system to a spatially nonuniform cavity mode, we analyze the emergence of a magnetostatic instability, namely, photon condensation, originating from the paramagnetic Van Vleck mechanism. The global behavior of the system is analyzed for different electronic filling factors, and we find that, except for the special cases of half filling and a single electron, where the transition, if it occurs, is necessarily a second-order phase transition, the global system may also undergo a first-order transition because of the action of the electron-electron interaction. The polaritonic excitation energies are analyzed, providing clear spectroscopic signatures of the magnetostatic instability and of its order.

The superconducting transition temperature $T_c$ of the two-dimensional attractive Hubbard model is computed in the vicinity of both ordinary (logarithmic) and higher-order (power-law) Van Hove singularities using determinant quantum Monte Carlo simulations. For interaction strengths $\left|U\right|\lesssim W/3$, where $W$ is the electronic bandwidth, $T_c$ is enhanced in the neighborhood of the Van Hove point, albeit more weakly than expected from weak-coupling BCS theory. Enhancing the Van Hove singularity from logarithmic to power-law yields only a minor additional enhancement of $T_c$. For $\left|U\right|\gtrsim W/3$, the maximum $T_c$ shifts away from the Van Hove point and instead occurs at a density unrelated to any features in the noninteracting density of states, consistent with a strong-coupling interpretation. We find that the maximal $T_c$ in the model is achieved at intermediate $U$ and at a density away from the Van Hove point.