Black phosphorus (BP) exhibits net opposite pseudospin polarizations for the electron and hole states. The pseudospin structure of BP causes a selectivity in the optical excitation engaging the symmetry between the optical pump polarization and the pseudospin state, which is confirmed in a simulation of the time-resolved angle-resolved photoemission spectroscopy (tr-ARPES). Further, the pseudospin selectivity is found to drive a unique polarimetric singularity in the high-harmonic generation (HHG). Given the $n\mathrm{th}$-order high-harmonic signal, we reveal that the singularity arises predominantly through the multiphoton interband pathway and thereby becomes markedly substantial at $n{\omega }_{\mathrm{pump}}\gtrsim E_g$. ${\omega }_{\mathrm{pump}}$ is the pump photon energy and $E_g$ the energy gap of BP. This permits a coherent understanding of the pseudospin selectivity from tr-ARPES to HHG. In particular, the pseudospin-selective polarimetric singularity suggests a potential for the pseudospintronics to be integrated into the intrinsic dynamics due to the light-matter interaction in two-dimensional materials.

Inspired by recent observations of the $1/3$ magnetization plateau in kagome-based magnets, we investigate the $J_1\text{−}{J}_2$ Heisenberg model on the kagome lattice under the influence of an external magnetic field. Although the classical ground state at zero field depends on the sign of $J_2$, we find a robust $1/3$ semiclassical magnetization plateau in both cases. The mechanism that stabilizes this plateau is analogous to that observed in the triangular lattice, where quantum fluctuations select a collinear state from the degenerate classical manifold. Using nonlinear spin-wave theory, we calculate the plateau width, which shows a weak dependence on $J_2$ but a strong dependence on the spin size $S$. Interestingly, we find that a straightforward approach based on linear spin waves yields quantitatively accurate results even for $S=1/2$. Furthermore, we identify a magnetization jump at the saturation field when $J_2=0$, originating from a flat magnon band. This jump disappears for $J_2\ne 0$, providing a semiclassical analog of the localized magnon crystal state observed for $S=1/2$. Our study demonstrates that a semiclassical approach effectively captures the $1/3$ plateau in the kagome lattice and serves as a valuable tool for interpreting both experimental and numerical results.

Altermagnets (AMs) exhibit vanishing net magnetization but strong momentum-dependent spin splitting enforced by crystal symmetry. Here, we explore the non-Hermitian (NH) effects in dissipative two-dimensional AMs. We show that symmetry-compliant dissipation naturally induces an imaginary staggered exchange field, driving an NH topological phase transition absent in conventional antiferromagnets. In the topologically nontrivial phase, hybrid skin-topological modes driven by altermagnetic $d$-wave anisotropy emerge, as captured by the chiral skin effect framework. In the gapless phase, we elucidate the creation and annihilation dynamics of exceptional points. Crucially, we analytically prove via the transfer matrix method that corner states are deterministically controlled by the boundary sublattice termination. Due to the symmetry constraints and the robustness of chiral states, these findings hold universally across all topological AMs. A general framework is established for controlling topological corner states, offering a new strategy for designing magnetic materials with tailored non-Hermitian properties.

In the context of a growing interdisciplinary interest in the angular momentum of wave fields, the spin-wave case has yet to be fully explored, with the extensively studied notion of spin transport being only part of the broader picture. Here we report experimental evidence for nonzero magnon orbital angular momentum inside magnetic disk by resolving the frequency splitting between magnon modes with counterrotating wavefronts and thereby avoiding formation of azimuthal standing waves. This requires an unambiguous formulation of spin and orbital angular momenta for spin waves, which we provide in full generality taking advantage of a systematic application of quantum field theory techniques as detailed in a companion paper [T. Valet et al., Phys. Rev. B 113, 104437 (2026)]. The results unequivocally establish magnetic dipole-dipole interactions as a magnetic-field controllable spin-orbit interaction for magnons. Our findings open a new research direction, leveraging the spectroscopic readability of angular momentum for azimuthal spin waves and other related systems.

We consider the scenario of excitons in a semiconductor bilayer that are strongly coupled to cavity photons, leading to the formation of dipolar exciton polaritons (dipolaritons). Using a realistic pseudopotential for the dipolar interactions, we exactly determine the scattering between dipolaritons, accounting for the hybridization between interlayer and intralayer excitons. Similar to conventional nondipolar polaritons, we find that the light-matter coupling enhances the interactions between dipolaritons by forcing excitons to scatter at energies that would otherwise be forbidden in ordinary exciton-exciton collisions. However, we show that this light enhancement is larger for long-range dipolar interactions than for short-range intralayer interactions, and is sensitive to the (nonuniform) dielectric environment of the bilayer. Crucially, we find that the largest dipolariton interactions are achieved for transition-metal dichalcogenide bilayers in vacuum. Our results thus reveal the optimal dipolariton setup for realizing strong photon correlations.

We investigate the entanglement properties of the Quantum Six-Vertex Model on a cylinder, focusing on the Shannon-Rényi entropy in the limit of Rényi order $n=\infty$. This entropy, calculated from the ground state amplitudes of the equivalent XXZ spin-1/2 chain, allows us to determine the Renyi entanglement entropy of the corresponding Rokhsar-Kivelson wave functions, which describe the ground states of certain conformal quantum critical points. Our analysis reveals a logarithmic correction to the expected entanglement scaling when the system size is odd. This anomaly arises from the geometric frustration of spin configurations imposed by periodic boundary conditions on odd-sized chains. We demonstrate that the scaling prefactor of this logarithmic term is directly related to the compactification radius of the low-energy bosonic field theory description or, equivalently, the Luttinger parameter. Thus, this correction directly probes the underlying Conformal Field Theory describing the critical point. Our findings highlight the crucial role of system size parity in determining this model's entanglement properties and offer insights into the interplay between geometry, frustration, and criticality.

Motivated by recent advancements in the Josephson diode effect and unconventional $p$-wave magnets (UPMs), we investigate the supercurrent in UPM/superconductor Josephson junctions by the Green's function method. The simultaneous presence of an out-of-plane Zeeman field and Rashba spin-orbit coupling within the UPM breaks the conventional current-phase relation $I\left(\phi \right)=-I(-\phi )$, yielding a Josephson diode effect with high rectification efficiency. The diode polarity and efficiency exhibit systematic oscillations as functions of the Néel vector orientation and strength, as well as Rashba spin-orbit coupling. We identify the conditions necessary for the emergence of the Josephson diode effect through symmetry analysis. Furthermore, the current-phase relation and the Josephson diode effect are sensitive to the orientation of the Néel vector, offering an alternative scheme for its electrical detection. These findings enhance the understanding of the Josephson diode effect in UPM-based Josephson devices and provide a novel detection method for the Néel vector in UPMs.

Starting from the purely microscopic model, we go beyond conventional mean-field theory and develop a self-consistent microscopic thermodynamic framework for disordered 2D superconductors. It incorporates the fermionic Bogoliubov quasiparticles, bosonic Nambu-Goldstone (NG) quantum and thermal phase fluctuations in the presence of long-range Coulomb interactions, and topological Berezinskii-Kosterlitz-Thouless (BKT) vortex-antivortex fluctuations on an equal footing, to self-consistently treat the superconducting gap and superfluid density. This unified phase-fluctuating description naturally recovers the previously known limiting results: the superconducting gap in the 2D limit can remain robust against long-wavelength NG phase fluctuations at $T=0^{+}$ due to Coulomb-induced regularization, while the gradual proliferation of BKT fluctuations as the system approaches criticality drives a separation between the global superconducting transition temperature $T_c$ and the gap-closing temperature $T^{*}$. In contrast to mean-field theory, which predicts 2D superconductivity to be independent of carrier density and nonmagnetic disorder (Anderson theorem), the incorporation of phase fluctuations generates a density- and disorder-dependent zero-point gap $\mathrm{\Delta }\left(0\right)$ and consequently $T_c$ and $T^{*}$. Remarkably, applications to bilayer ${\mathrm{MoS}}_2$ [Nat. Nanotechnol. 14, 1123 (2019)] and disordered ${\mathrm{InO}}_x$ thin films [Nat. Phys. 21, 104 (2025)] quantitatively reproduce key experimental observations in excellent agreement. The framework offers a useful theoretical tool for understanding phase-fluctuation-dominated superconductivity.

In ultrafast experiments on superconductors, a pump laser pulse often heats up the electronic system and suppresses the density of superfluid electrons. Subsequently, the electrons undergo a cooling process because of electron-phonon thermalization so that the superfluid density recovers in time. We study the nonequilibrium electromagnetic response of the system in this cooling process. We show that if a supercurrent is initiated by a probe electric field pulse, an intriguing phenomenon of ‘‘supercurrent growth’’ occurs, meaning that the net current grows in time with the increasing superfluid density. Using the Boltzmann kinetic equation, we uncover its microscopic origin as the momentum-relaxing scattering of Bogoliubov quasiparticles by impurities and phonons, in stark contrast to the widely accepted intuition that impurities always attenuate currents. We further show that supercurrent growth has important experimental manifestations, including the ultrafast Meissner effect and an optical reflectivity exceeding unity.

The mechanical behavior of semiconductors is critical to the reliability of microelectronic, power, photonic, and sensing devices, notably under multiphysical stimuli, e.g., light illumination and stress. Zinc sulfide (ZnS), a prototype II–VI semiconductor, exhibits a positive photoplastic effect, with an increased strength and reduced plastic deformability under light illumination. Yet, the atomistic mechanisms behind such light-induced mechanical modulation remain not well understood. In this study, we perform molecular dynamics simulations with machine-learned force fields to investigate the deformation behavior of ZnS nanopillars under both dark and illuminated conditions. Three representative crystallographic orientations ([001], $\left[1\overline{1}0\right]$, [111]) are considered to understand the plastic anisotropy in it. Our simulation results reveal that phase transformation, rather than dislocation glide, dominates the plastic flow in ZnS under deformation along [001] direction. In contrast, the shear banding-induced brittle failure occurs when ZnS is compressed along two other directions ($\left[1\overline{1}0\right]$ and [111]). Under light illumination, the yield stress of ZnS increases by at least 4.2% across all the three orientations, but with different mechanisms underlying them. In detail, when the sample is compressed along [001] direction, the strength enhancement arises primarily because photoexcited charge carriers delay the phase transformation. Instead, when the sample is deformed along $\left[1\overline{1}0\right]$ and [111] directions, the yielding strength is enhanced because illumination suppresses shear localization and delays failure initiation in the brittle failure orientations. This work provides atomistic insight into how illumination modulates the plastic flow in ZnS under deformation.

Compared to its ferromagnetic (FM) counterpart, the Griffiths singularity arising from antiferromagnetic (AF) rare regions remains much less explored. Here, we investigate this rare-region effect in Fe-doped perovskite manganites ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}}_{1-y}{\mathrm{Fe}}_y{\mathrm{O}}_3$ (LSMFO). We observe that Fe doping suppresses the long-range FM order and induces a metal-to-insulator transition at a percolation threshold $y_c^{\mathrm{MI}}\simeq 0.18$, dual to the insulator-to-metal transition at $x_c^{\mathrm{IM}}\simeq 0.175$ in ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_x{\mathrm{MnO}}_3$ (LSMO). Extending this percolation duality, we find corroborating evidence for a dual AF Griffiths phase in LSMFO, with a percolation threshold $y_c^{\mathrm{AG}}$ closely mirroring that of the FM Griffiths phase in LSMO $(x_c^{\mathrm{FG}}\simeq 0.07)$. Furthermore, we demonstrate that strong disorder and frustration, mediated by the Griffiths rare regions, destabilize both long-range FM and AF correlations, culminating in a low-temperature spin glass state for $y\ge 0.18$. Our work thus establishes a unified perspective for understanding rare-region effects in systems involving competing FM and AF exchange interactions.

Nonreciprocal propagation of energy and information is fundamental to a wide range of quantum technology applications. In this work, we explore the quantum many-body dynamics of a qubit ensemble coupled to a shared bath that mediates coherent and dissipative interqubit interactions with both symmetric and antisymmetric components. We find that the interplay between antisymmetric (symmetric) coherent and symmetric (antisymmetric) dissipative interactions results in nonreciprocal couplings, which, in turn, generate a spatially asymmetric emission pattern. We demonstrate that this pattern arises from nonreciprocal interactions coupling different quantum many-body states within a specific excitation manifold. Focusing on solid-state baths, we show that their lack of time-reversal and inversion symmetry is a key ingredient for generating nonreciprocal dynamics in the qubit ensemble. With the plethora of quantum materials that exhibit this symmetry breaking at equilibrium, our approach paves the way for realizing cooperative nonreciprocal transport in qubit ensembles without requiring time-modulated external drives or complex engineering. Using an ensemble of nitrogen-vacancy (NV) centers coupled to a generic noncentrosymmetric ferromagnetic bath as a concrete example, we demonstrate that our predictions can be tested in near-future experiments. Additionally, we find that the spatial asymmetry in the relaxation dynamics increases with the size of the qubit ensemble and persists over longer interqubit distances than the signatures of super- and subradiant collective relaxation dynamics. As the spatial asymmetry in the relaxation dynamics of the qubit ensemble is a direct probe of symmetry breaking in the solid-state bath, our work also opens the door to developing model-agnostic quantum sensing schemes capable of detecting bath properties invisible to current state-of-the-art protocols, which operate solid-state defects as single-qubit sensors.

Recently, (101)-oriented $\mathrm{Ru}{\mathrm{O}}_2$ films have been intensively studied because of their ability to generate a spin current with out-of-plane polarization, enabling field-free switching of perpendicular magnetization. This unconventional spin current has typically been attributed to the altermagnetic spin splitting effect in $\mathrm{Ru}{\mathrm{O}}_2$. In this study, we investigate the spin-charge interconversion in $\mathrm{Ru}{\mathrm{O}}_2\left(101\right)$ films through the spin Seebeck effect and spin-orbit torque induced magnetization switching measurements. By comparing the reciprocal relations in $\mathrm{Ru}{\mathrm{O}}_2\left(101\right)$ and the conventional heavy metal Pt, we find that the out-of-plane polarized spin current generated in our $\mathrm{Ru}{\mathrm{O}}_2\left(101\right)$ film is dominated by the anisotropic spin Hall effect. Our work not only enriches the understanding of spin transport in $\mathrm{Ru}{\mathrm{O}}_2$ but also establishes a straightforward and effective approach for distinguishing the altermagnetic spin splitting effect and spin Hall effect.

We study the Ising model with competing ferromagnetic nearest- and antiferromagnetic next-nearest-neighbor interactions of strengths $J_1>0$ and $J_2<0$, respectively, on the honeycomb lattice. For $J_2>-J_1/4$ it has a ferromagnetic ground state, and previous work has shown that at least for $J_2\gtrsim -0.2J_1$ the transition is in the Ising universality class. For even lower $J_2$ some indicators pointing towards a first-order transition were reported. By utilizing population annealing Monte Carlo simulations together with a rejection-free and adaptive update, we can equilibrate systems with $J_2$ as low as $-0.23J_1$. By means of a finite-size scaling analysis we show that the system undergoes a second-order phase transition within the Ising universality class at least down to $J_2=-0.23J_1$ and, most likely, for all $J_2>-J_1/4$. As we show here, there exist very long-lived metastable states in this system explaining the first-order like behavior seen in only partially equilibrated systems.

We develop a linear response theory for the dynamical proximity effect in topological superconductor/ferromagnetic insulator (TS/FI) hybrids. Our approach integrates the nonequilibrium quasiclassical Keldysh-Usadel formalism for the TS with the Landau-Lifshitz-Gilbert equation for the FI's magnetization dynamics. This framework reveals a proximity-induced coupling between magnons and superconducting collective modes. Crucially, we find that spin-momentum locking in the TS surface state drives a hybridization between magnons and the superconducting Nambu-Goldstone (phase) mode, giving rise to composite magnon–Nambu-Goldstone excitations. We analyze the coupling strength's dependence on key parameters both analytically and numerically. In contrast, we demonstrate that the Higgs (amplitude) mode does not couple to magnons at linear order and is thus excluded from the hybrid excitation spectrum. The hybridization between magnons and the superconducting phase mode provides a mechanism for the interconversion of spin signals and the spinless signals carried by collective superconducting excitations, thereby giving impetus to the development of superconducting spintronics.

Combining geometrical frustration and one-dimensional magnetism boosts quantum fluctuations and leads to unusual states of quantum matter. We report the magnetic behavior of a well-separated $S=\frac{5}{2}$ sawtooth spin chain compound ${\mathrm{CaFe}}_2\mathrm{O}{\left({\mathrm{PO}}_4\right)}_2$ (CFPO). Magnetic susceptibility, heat capacity, and ${}^{31}\mathrm{P}$ nuclear magnetic resonance measurements show evidence of strong magnetic frustration in the compound. Despite a relatively large antiferromagnetic Curie-Weiss temperature of about $-1073\mathrm{K}$, the compound exhibits multiple magnetic transitions at low temperatures at 15.5, 10.4, and 7.8 K, respectively, with a frustration parameter $\left(\mathit{f}\approx |{\theta }_{\text{CW}}|/T_{\text{N}}\right)$ about 70. The Knight shift shows a broad maximum around 70 K for P1 and P2 sites. The spin-lattice relaxation rate $1/T_1$ follows temperature-independent behavior well above the long-range order (LRO). First-principles calculations capture the strong antiferromagnetic interactions in this quasi-one-dimensional sawtooth lattice, providing a microscopic explanation for the experimentally observed frustration, low dimensionality, and the onset of LRO at low temperatures. Our results indicate that CFPO exhibits the presence of short-range correlations and persistent spin dynamics characteristics above the LRO, which probably stem from the $S=\frac{5}{2}$ sawtooth spin chain model.

The precise role of electron-phonon $\left(e\text{−}\mathrm{ph}\right)$ coupling in graphene and related materials on a honeycomb lattice is not yet fully understood, despite extensive research on these systems. Here, we perform sign-problem-free determinant quantum Monte Carlo simulations of the optical Su-Schrieffer-Heeger (oSSH)-Hubbard model on the honeycomb lattice, focusing on the parameters relevant to graphene. Performing finite-size scaling analyzes, we obtain the model's ground-state phase diagram, which includes the semi-metal (SM), Kekulé valence bond solid (KVBS), and antiferromagnetic (AFM) phases, as well as indications of a small KVBS/AFM coexistence region. We find that a weak to moderate Hubbard repulsion, tuned toward the SM-AFM critical value in the pure honeycomb Hubbard model, enhances KVBS correlations and can even stabilize the KVBS phase. Estimating the effective parameters for graphene places it in the SM region of the phase diagram, but near the SM-KVBS phase boundary. Notably, we predict that increasing either the on-site Hubbard repulsion or the $e\text{−}\mathrm{ph}$ coupling strength drives graphene toward the KVBS phase rather than the AFM phase, highlighting a synergistic effect that can be exploited to further control the remarkable properties of graphene and related materials.