Altermagnets naturally host handedness-splitting magnon modes, providing a promising platform for low-dissipation and ultrafast handedness-based computing. However, achieving precise and active control over the magnon handedness remains a challenge. Here, we propose a mechanism for the electrical switching of magnon handedness in altermagnets via interfacial Rashba spin-orbit coupling (SOC), which is free of tuning external excitation fields. For an in-plane polarized magnetic ground state, SOC induces a splitting effect that inherently competes with the altermagnetism. Strong-coupling perturbation expansion reveals that this competition originates microscopically from a dynamically induced next-nearest-neighbor Dzyaloshinskii-Moriya interaction. This destructive interference leading to a macroscopic momentum-space reversal of both the electronic spin splitting and the magnon handedness splitting. Consequently, tuning the SOC strength enables a deterministic switching of the dominant precessional handedness under fixed resonance conditions. We further propose an experimental setup utilizing an altermagnet/insulator heterostructure to validate this mechanism. Our work establish a pathway toward the efficient electrical manipulation of magnon excitations, facilitating the development of handedness-based magnonic devices.

This paper proposes a technique for identifying the contributions of various physical phenomena to the total electrical potential difference that arises between electrical contacts at the ends of a ferromagnetic-metal/nonmagnetic-metal film structure under ferromagnetic resonance (FMR) conditions. The technique is based on a combined analysis of both FMR spectra and electrical potential difference signals. This technique allows for the use of two procedures, each providing a complete set of the desired information. Both procedures of the proposed technique were applied to a ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_3$/${\mathrm{SrIrO}}_3$ film structure grown epitaxially in a single cycle on a single-crystal ${\mathrm{NdGaO}}_3$ substrate. Presented work shows that in this structure the electric voltage signal contains contributions from three physical processes: the inverse spin Hall effect, the anomalous Hall effect and anisotropic magnetoresistance. The quantitative agreement between the obtained results confirms the validity of the analytical expressions used.

We investigate the magnon band topology and transverse transport in an antiferromagnetic $\alpha \text{−}{T}_3$ lattice with Dzyaloshinskii-Moriya interaction (DMI) and single-ion anisotropy. Using linear spin-wave theory, we show that the lattice geometry, controlled by the parameter $\alpha$, together with the DMI, drives a topological phase transition when the two lower magnon bands become degenerate at the $\mathbf{K}$ point of the first Brillouin zone. The transition occurs along the critical line $D/J_1=(1-\alpha )/2\sqrt{3}$, separating a trivial phase with Chern numbers $C=(0,0,0)$ from a nontrivial phase with $C=(-2,2,0)$. This topological transition is directly manifested in the transverse transport of magnons. At $k_{B}T=J_1$, the magnon spin Nernst and thermal Hall coefficients increase by up to a factor of 3 and 8, respectively, when the system transitions from the trivial to the topological phase, driven by the large Berry curvature near the $\mathbf{K}$ point. We also examine the effect of sublattice inequivalence and demonstrate that the essential connection between nontrivial topology and enhanced transport remains robust. Our results establish the $\alpha \text{−}{T}_3$ antiferromagnet as a tunable platform for topological magnonics and provide clear theoretical predictions for experimental detection.

Magnetic nanoparticles beyond the single-domain limit often develop vortexlike magnetization textures arising from the competition between exchange and magnetostatic energies. While such states are routinely studied using micromagnetic simulations, transparent analytical descriptions of vortex-mediated hysteresis and nucleation remain scarce. Here, we develop a semianalytical minimal framework for vortex states in spherical magnetic nanoparticles. Guided by micromagnetic simulations, we introduce a parametrized vortex magnetization Ansatz based on hyperbolic functions that continuously interpolates between uniform and vortex states. In this way, we achieve a complexity reduction leading to a minimal Hamiltonian, which enables the efficient computation of magnetization curves and provides insight into vortex-mediated magnetization reversal. As an application, we derive analytical estimates for the critical vortex nucleation radius and field, recovering the functional form of Brown's classic result and extending it within a variational framework.

The coupling between real-space inhomogeneity coordinates and spin $\left(\mathbf{r}\text{−}\mathbf{s}\right)$ provides an alternative route to achieve efficient spin manipulation in spintronics beyond the conventional momentum-spin $\left(\mathbf{k}\text{−}\mathbf{s}\right)$ coupling paradigm. Here, we demonstrate an unexpected manifestation of one-dimensional (1D) $\mathbf{r}\text{−}\mathbf{s}$ coupling via floating edge states in two-dimensional altermagnets with electric-field and gate-doping tunability. The 1D edge-spin $\mathbf{r}\text{−}\mathbf{s}$ coupling ensures that carrier transport is exclusively carried by the edge states with quantized spin conductance, giving rise to an unconventional edge tunnel magnetoresistance effect that can be switched on or off. As a proof of concept, we computationally design an altermagnetic edge tunnel junction based on a ${\mathrm{Cr}}_2{\mathrm{Se}}_2\mathrm{O}$ monolayer to demonstrate its edge transport and controllability via the Néel order or an electric field. Our findings propose a general prototype altermagnetic device for next-generation low-dimensional spintronics.

Triangular atomic arrangements exhibit exceptional physical properties and can host diverse magnetic states, serving as an outstanding platform for investigating the interplay between magnetism, symmetry, and electronic transport. In this study, we reveal a large, tunable, and switchable anomalous Hall effect in a kagome-like-lattice ferromagnet ${\mathrm{Mn}}_5{\mathrm{Ge}}_3$, utilizing ab-initio calculations and electrical transport measurements. We find that the intrinsic anomalous Hall conductivity (AHC) in ${\mathrm{Mn}}_5{\mathrm{Ge}}_3$ shows switchable anisotropy with magnetic moment M oriented along different axes. Our theoretical calculations suggest that this large AHC is closely linked to the topological nodal rings in the band structure near the Fermi level and is strongly influenced by the Ge occupancy at the 2b site. Experimental data indicate that the AHC can reach up to 1053 S/cm when the current is applied along [120], and the magnetic field is along [001] in ${\mathrm{Mn}}_5{\mathrm{Ge}}_{3+x}$ single crystal with approximately $x=0.33$ Ge doping. We show that in kagome-like structures, atomic doping at specific lattice sites enables precise modulation of topological electronic properties while maintaining structural and symmetry integrity. This approach offers a unique pathway for designing novel quantum materials with tunable electronic properties, highlighting its potential for advancing the development of next-generation quantum devices.

We study a strongly interacting quantum dot connected to two superconducting leads using a slave-spin representation of the dot. At the mean-field level, the problem maps to a resonant level model with superconducting leads, coupled to an auxiliary spin-1/2 variable accounting for the parity of the dot. We obtain the mean-field phase diagram, showing a transition between a Kondo (singlet) and a local moment (doublet) regime, corresponding to the $0\text{−}\pi$ transition of the junction. The mean-field theory qualitatively captures the Kondo singlet phase and its competition with superconductivity for weak values of the Bardeen-Cooper-Schrieffer (BCS) gap, including the nontrivial dependence of the Andreev bound states on the interaction, but fails in the doublet regime where it predicts a dot decoupled from the bath. Using diagrammatic techniques and a random-phase approximation, we include fluctuations on top of the mean-field theory to describe finite-frequency dynamics of the effective spin variable. This leads to the formation of high-energy Hubbard bands in the spectral function and a coherent Kondo peak with a BCS gap at low energies. We compute the Josephson current and the induced superconducting correlations on the dot. Finally, we evaluate the microwave response in the strongly interacting Kondo regime.

We investigate the critical current in microwave-irradiated Josephson junctions hosting Yu-Shiba-Rusinov states due to magnetic impurities. Under two conditions, namely (i) the breaking of particle-hole symmetry in the normal sense by nonzero potential scattering and (ii) the breaking of inversion symmetry either by unequal magnitudes of potential scattering and/or magnetic moments, microwave irradiation induces an additional phase-independent contribution to the current. This leads to asymmetric critical currents for opposite current polarities, an effect absent in the same junction without microwave irradiation. The asymmetry is highly tunable via the microwave amplitude and frequency, and we may even achieve perfect asymmetry where the critical current vanishes for one polarity, akin to a perfect diode. While Yu-Shiba-Rusinov states provide the ideal platform for a pronounced asymmetry, we find that as long as the two conditions (i) and (ii) above are met, our proposal does not necessarily depend upon them.

It is well known that the current-biased Josephson junction can serve as a Josephson threshold detector (JTD) for the sensitive detection of weak microwave signals. In a recent work [Phys. Rev. B 111, 024501 (2025)], we showed that the achievable detection sensitivity of the usual JTD can approach only the energy limit of the detected microwave signal, due to the always-on thermal noise. Here, we numerically demonstrate that the thermal noise can be effectively suppressed by increasing the sweep rate of the biased current, driving the JTD to be operated in a nonequilibrium state (It only refers to insensitivity to the equilibrium thermal noise, rather than the realistic thermodynamic nonequilibrium state.) with the measurable switching current distribution (SCD) being insensitive to the thermal noise. Therefore, by identifying the measured SCDs of the nonequilibrium JTD with and without the microwave signal input, the weak microwave signal could be sensitively detected at its energy quantum limit. Some of the achievable performance indexes of the nonequilibrium JTD, such as the dynamic range, detection bandwidth, and the photon-number resolvability, etc., have also been numerically estimated when it serves as a wideband microwave single-photon detector.

Iron-based superconductors offer a versatile platform for exploring topological superconductivity and Majorana zero modes (MZMs), with experimental confirmations in Fe(Te,Se), (Li,Fe)OHFeSe and $\mathrm{Ca}\mathrm{K}\mathrm{F}{\mathrm{e}}_4\mathrm{A}{\mathrm{s}}_4$ at ambient pressure, as well as in LiFeAs under local strain. The related properties in other iron-based superconductors still need to be explored, especially under the application of local strain. In this study, we conduct scanning tunneling microscopy/spectroscopy measurements on $\mathrm{Cs}\mathrm{C}{\mathrm{a}}_2\mathrm{F}{\mathrm{e}}_4\mathrm{A}{\mathrm{s}}_4{\mathrm{F}}_2$ crystals under unidirectional local strain. A fully developed superconducting gap with multiple pairs of coherence peaks are observed, and the gap sizes can be significantly modulated by local strain. Spectroscopic measurements on various types of defects including the nonmagnetic Cs-site vacancies consistently reveal pair-breaking effects. These phenomena support a fully gapped multiband superconductivity scenario with sign changing. Notably, a sharp zero-energy conductance peak (ZECP) is universally observed on a particular type of defects by using a metallic tip, resembling the MZMs observed at interstitial Fe atoms in Fe(Te,Se) [Yin et al., Nat. Phys. 11, 543 (2015)]. However, by using a superconducting tip to enhance energy resolution as well as by studying the ZECP evolution as functions of magnetic field and tunneling transmissivity, we demonstrate that the ZECP originates from nearly degenerate impurity-induced bound states rather than MZMs. Our study not only provides more insights into the superconducting pairing symmetry of $\mathrm{Cs}\mathrm{C}{\mathrm{a}}_2\mathrm{F}{\mathrm{e}}_4\mathrm{A}{\mathrm{s}}_4{\mathrm{F}}_2$ but also establishes systematic experimental methods for identifying weak impurity state signals and discerning the physical origins of ZECPs.

Niobium-based dichalcogenides $({\mathrm{NbX}}_2, \text{where} \mathrm{X}=\mathrm{S}, \mathrm{Se}, \mathrm{Te})$ exhibit tunable intertwining charge density waves (CDWs) and superconductivity, especially ${\mathrm{NbSe}}_2$ and ${\mathrm{NbTe}}_2$, which have attracted much attention due to their abundant electronic properties. However, the evolution of CDWs and superconductivity from ${\mathrm{NbSe}}_2$ to ${\mathrm{NbTe}}_2$ remains elusive. Here, using ultralow temperature scanning tunneling microscopy and spectroscopy (STM/STS) at 400 mK, we discover local short-range CDW patterns in 1T-NbSeTe, in which the three CDW components are spatially decoupled, indicating that the CDW in 1T-NbSeTe resides in a melted state of the 3 × 3 CDW of $2\mathrm{H}\text{−}{\mathrm{NbSe}}_2$ and 3 × 1 CDW orders of $1{\mathrm{T}}^{″}\text{−}{\mathrm{NbTe}}_2$. The short-range CDWs coexist with the superconductivity below a critical temperature of ∼1.5 K and an upper critical field of ∼1.7 T. The scaling relationship between the zero-energy density of states and the superconducting gap across a single vortex indicates that 1T-NbSeTe is a dirty superconductor. These findings provide valuable insights into the doping induced CDW melting and superconducting states in transition metal dichalcogenides.

We use determinant quantum Monte Carlo to study the half-filled ‘‘bond-Holstein’’ model on a square lattice. We find that the model exhibits a charge-density-wave (CDW) phase transition with a critical temperature $T_{\mathrm{cdw}}$ considerably higher than that of the canonical ‘‘site-Holstein’’ model. Using a finite-size scaling analysis of the charge structure factor $S_{\mathrm{cdw}}$, we obtain $T_{\mathrm{cdw}}$ to greater than 1% accuracy. At the same time, local observables also show clear signatures consistent with the transition temperatures inferred from our scaling analysis. We attribute the enhanced CDW tendencies to a phonon-mediated nearest-neighbor electron repulsion that is directly proportional to the dimensionless electron-phonon coupling $\lambda$ in the atomic ($t\to 0$) limit. This behavior contrasts with the site-Holstein case, where the same limit yields only an on-site attraction. We supplement our analysis with results from several unsupervised machine learning methods, which not only confirm our estimates of $T_{\mathrm{cdw}}$ but also provide insight into the high-temperature crossover between a metallic and bipolaron liquid regime.

Two-dimensional honeycomb magnets with low coordination numbers provide an ideal framework for investigating the interplay between lattice geometry, reduced dimensionality, and magnetic interactions. While low-spin honeycomb systems have been extensively studied, high-spin counterparts remain comparatively unexplored, despite their importance for understanding the classical limit of magnetism. In this work, we present a comprehensive investigation of ${\mathrm{SrFeSnP}}_3{\mathrm{O}}_{12}$, a two-dimensional (2D) honeycomb lattice compound in which ${\mathrm{Fe}}^{3+}$ ions ($S=5/2$) form a well-defined magnetic network. Magnetic susceptibility measurements reveal a transition at $T_N=13\mathrm{K}$, signaling the onset of long-range antiferromagnetic order, which is further supported by heat capacity measurements. Nuclear magnetic resonance (NMR) measurements confirm the development of internal magnetic fields below $T_N$, while the sublinear temperature dependence of the spin-lattice relaxation rate above $T_N$ provides evidence for short-range spin correlations in the paramagnetic regime. Electron spin resonance measurements reveal a single isotropic resonance at high temperatures, indicating isotropic spin correlations within the 2D honeycomb lattice. Theoretical calculations of symmetric exchange interactions show that the nearest-neighbor in-plane exchange interaction $J_1$ is the dominant one and antiferromagnetic in nature. Our computed $\text{Fe-}d$ Wannier functions show that the interaction is mediated via Fe–O–P–O–Fe superexchange pathway. Our calculation in the presence of spin-orbit coupling shows that the system has negligible magnetic anisotropy, suggesting an isotropic 2D Heisenberg spin model relevant for the system. Local probe measurements, such as electron spin resonance and NMR, together with specific heat data, indicate the development of short-range antiferromagnetic correlations that persist well above the long-range ordering temperature. These results establish ${\mathrm{SrFeSnP}}_3{\mathrm{O}}_{12}$ as a model high-spin honeycomb magnet bridging the classical and quantum regimes of magnetism.

We investigate the non-Hermitian Kitaev chain with nonreciprocal hopping amplitudes and asymmetric superconducting pairing. We work out the symmetry structure of the model and show that particle-hole symmetry (PHS) is preserved throughout the entire parameter regime. As a consequence of PHS, the topological phase transition point of a finite open chain coincides with that of the periodic (infinite) system. By explicitly constructing the zero-energy wave functions (Majorana modes), we show that Majorana modes necessarily occur as reciprocal localization pairs accumulating on opposite boundaries, whose combined probability density exhibits an exact cancellation of the non-Hermitian skin effect for the zero-energy modes. Excited states, by contrast, generically display skin-effect localization, with particle and hole components accumulating at opposite ends of the system. At the level of bulk topology, we further construct a ${\mathbb{Z}}_2$ topological invariant in restricted parameter regimes that correctly distinguishes the topological and trivial phases. Finally, we present the topological phase diagram of the non-Hermitian Kitaev chain across a broad range of complex parameters and delineate the associated phase boundaries.

We propose that x-ray absorption and emission magnetic circular dichroism (XAS-MCD and XES-MCD) are promising measurements to directly detect ferroic higher-rank multipoles as candidate order parameters in altermagnets. Using the sum rules for XES-MCD and connecting them to multipole language, we demonstrate that the expectation value of the magnetic octupole moment is finite in the $d$-wave altermagnetic candidate rutile-type compounds ${\mathit{T}\mathrm{F}}_2$ (T = transition metal). We also perform spectral calculations of XAS-MCD and XES-MCD based on an effective model with a full multiplet approach. While the intensity of the XAS-MCD spectra vanishes, the XES-MCD spectra exhibit finite intensity, whose spectrum becomes opposite by inverting the Néel vector. These results clearly indicate ferroic magnetic octupole order in these compounds.

Fractional Chern insulators arise in topologically nontrivial flat bands, characterized by an integer Chern number $\mathit{C}$ that corresponds to the number of dissipationless edge states in the noninteracting regime. Higher Chern numbers can replicate the physics of higher Landau levels and often confer enhanced topological robustness. However, realizing correlated fractional phases with higher Chern numbers in such flat band systems remains challenging. Here, we propose an interlayer coupling scheme to generate higher Chern numbers in a flat-band system, where the interlayer coupling transforms two $\mathit{C}=\text{1}$ bands in a bilayer checkerboard lattice into a single flat band with $\mathit{C}=\text{2}$ by lifting their degeneracy and merging their topological indices. Exact diagonalization calculations reveal that this engineered band hosts two fractional Chern insulator states with many-body Chern numbers $\mathit{C}=2/3$ and 2/5 at fillings of $\nu =1/3$ and 1/5, respectively. An experimental setup is proposed to simulate these states using cold alkaline-earth-like atoms in an effective bilayer optical lattice. Our work provides a general and widely applicable strategy for constructing higher Chern number flat bands, opening a pathway to explore exotic fractional quantum phases.

We investigate a valleytronic method to enhance net phonon absorption by electrons (phonon valleytronics), enabling improved in situ thermoelectric cooling in heterostructured semiconductor devices. We show that electron energy filtering at a heterojunction barrier, combined with tailored valley offsets, generates a nonequilibrium carrier distribution that favors certain intervalley phonon absorption transitions. Using an analytic model and ensemble Monte Carlo simulations for thin ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ barriers, we demonstrate that this effect leads to a thermionic current sustained by phonon absorption-mediated $\mathrm{\Gamma }\to \mathrm{L}/\mathrm{X}$ transitions. With intervalley phonon harvesting, the phonon-electron conversion efficiency (coefficient of performance) increases by a factor of more than two compared with conventional solid-state thermionic energy filtering, under moderate bias at 300 K.

We theoretically investigate the three-dimensional (3D) electron dynamics of graphene in real space under strong laser fields using time-dependent density functional theory (TDDFT). We successfully reproduce the reversal of current direction originating from the cancellation of two oppositely directed residual currents, as previously predicted by [Y. Morimoto et al., New J. Phys. 24, 033051 (2022)]. By distinguishing contributions from individual orbitals, our results validate the two-level system approximation and also emphasize that the first-principles approach agrees better with experimental results for light-driven residual current, especially in extremely strong fields. Furthermore, our 3D model reveals that the real-space atomic-scale current induced by strong laser fields is concentrated slightly above and below the graphene basal plane, rather than strictly within it. The two oppositely directed currents exhibit a pronounced height separation in the out-of-plane direction, indicating that the ring current is not confined to the graphene plane but forms a rotating 3D circulation loop, which is absent in the reduced-dimensional model.

Charge Kondo circuits consist of metallic islands connected by single-mode quantum point contacts (QPCs). The island's charging energy makes these circuits tunable quantum simulators of various strongly interacting models. Here we propose a circuit that realizes the Kondo effect with effective Luttinger-liquid interactions, and show that it undergoes a localization transition in which the QPC transmission is fully suppressed below a critical value. Experimental signatures include a diverging charge susceptibility and an entropy step. Our findings open a path toward realizing localization transitions in more exotic settings.