Anderson transition, describing the disorder-driven change from extended quantum states to localized ones, plays a fundamental role in understanding wave transport in disordered systems. Here, we realize Anderson transition in a cascaded cavity-magnon system by mapping it to an effective Su-Schrieffer-Heeger model. Within this framework, on-site magnonic disorder is partially transferred—via linear cavity-magnon coupling—to cavity-dominated polaritons, introducing what we term “pseudo-disorder” into the topological chain. Beyond verifying bulk-boundary correspondence in both Hermitian and non-Hermitian regimes, we identify Anderson localization through Poisson-distributed level-spacing statistics. Moreover, under non-Hermitian conditions, we observe that non-Bloch $\mathcal{PT}$-symmetry-like breaking triggers a transition from real-energy to complex-energy localized modes. This work deepens the understanding of disorder-induced localization in non-Hermitian topological systems and reveals the spectral signatures of the Anderson transition beyond the Hermitian paradigm.

We investigate the symmetry-enforced line nodes of the triplet excitations of $X{\mathrm{CuCl}}_3$ ($X=\mathrm{Tl},\mathrm{K}$), showing that they are protected by nonsymmorphic symmetries and are unaffected by microscopic details, such as interaction and anisotropy strength, as long as the ground state and the symmetry group remain unchanged. Extending the conventionally used isotropic spin model for $X{\mathrm{CuCl}}_3$, our analysis includes all the symmetry-allowed anisotropies and gives a detailed account of the role they play in the band topology of triplets. We show that the triplet line nodes carry nontrivial Berry phases and compute their ${\mathcal{Z}}_2$ topological indices. To investigate the effect of breaking the nonsymmorphic symmetry protecting the triplet nodes, we applied a magnetic field tilted away from the high symmetry (010) axis. We find that while the $g$-tensor anisotropy behaves as a trivial mass gapping out the triplets, exchange anisotropies supply a nontrivial momentum-dependent mass term. Analogous to Haldane's original model, the competition of these mass terms determines the nature of the band topology in $X{\mathrm{CuCl}}_3$. To enable an analytic study of the band topology, we derive an effective Dirac Hamiltonian and validate it by computing the band structure and topological indices in the nodal line and gapped phases from the linear bond-wave formalism.

Pure spin current generation in two-dimensional (2D) altermagnets is of considerable interest in spintronics. Here, we develop a general phenomenological formalism for the spin Hall effect driven by the circular bulk photovoltaic effect (BPVE) in 2D semiconducting altermagnets with $C_{4\text{v}}$ and $D_{2\text{d}}$ symmetry. In such altermagnetic systems, the spin splitting in the momentum space is alternated between the $\mathrm{\Gamma }\to X$ and $\mathrm{\Gamma }\to Y$ directions, and the photoresponse tensor of the BPVE, ${\gamma }_{xy}$ and ${\gamma }_{yx}$ are equal in magnitude. This enables the generation of a pure spin current along the transverse direction, while a charge current along the longitudinal direction, thereby inducing the spin Hall effect via the circular BPVE. The spin Hall angle can be calculated from the spin-polarized photoresponse tensors. Specifically, we demonstrate through first-principles calculations and quantum transport simulations that a sizable spin Hall effect can be induced in the 2D altermagnet ${\mathrm{V}}_2\mathrm{SeTeO}$($C_{4\text{v}}$ symmetry), which exhibits a spin Hall angle much larger than 1, indicating high efficiency in pure spin current generation. Our results show the promise of altermagnets for spintronic applications.

We characterize optical transitions of neodymium ions $\left({\mathrm{Nd}}^{3+}\right)$ in antiferromagnetic neodymium gallate $\left({\mathrm{NdGaO}}_3\right)$ with applied fields up to 3 T. The magnetic phase of this material has not previously been studied with the field along its magnetization axis. The measured optical spectra indicate three magnetic phases—antiferromagnetic, intermediate, and saturated—where the intermediate phase likely forms a different magnetic structure from typical spin-flop phases. The observed absorptions were classified into two distinct families of optical transitions: single-Nd and two-Nd absorptions. We demonstrate that the optical transitions in the antiferromagnetic and saturated phases can be modeled using a standard single-ion crystal-field Hamiltonian that interacts with a mean magnetization from the rest of the lattice, and we expand that model to encompass pairs of ions, explaining the origins of the two-Nd transitions. This study offers a deeper understanding of the optical transitions in rare-earth antiferromagnetic crystals, which have been recently attracting significant interest for microwave-to-optical quantum transduction, despite being relatively unexplored to date.

We examine, both experimentally and theoretically, the behavior of an incommensurate magnetic helicoidal structure in a magnetic field applied in the plane in which spins lie. The experimental study is performed on the multiferroic ${\mathrm{NdFe}}_3{\left({\mathrm{BO}}_3\right)}_4$ using bulk magnetic measurements and single-crystal neutron diffraction. We obtain that the wave vector of the helicoidal magnetic structure remains unchanged upon the field increasing until 0.9 T, when the first-order transition to the commensurate spin-flopped antiferromagnetic structure takes place. We propose a theoretical model describing this field evolution. It is shown that the field-induced distortion of the incommensurate magnetic helix can be deduced from the field evolution of the uniform magnetization and intensities of magnetic satellites measured by the single-crystal neutron diffraction.

Static compression experiments using diamond anvil cells (DAC), combined with x-ray diffraction (XRD) are widely used to study material properties at extreme pressures. Recent advances enable time-resolved XRD during dynamic compression along tailored loading paths. However, the influence of compression rate on derived properties remains poorly understood, and the use of tailored compression paths—particularly pressure cycling—requires further investigation. Here, we employed time-resolved XRD in a dynamic DAC to compress MgO in a Ne pressure medium along a tailored compression path consisting of a ramp, plateau, and cyclic loading. Pressure-volume relations derived from ramp compressions at average compression rates of 0.22 and $0.46\mathrm{GPa}{\mathrm{s}}^{-1}$ agree closely with previous static experiments, with minor but detectable systematic deviations in the faster compression run. Stress analysis suggests that this deviation might be related to an increased flow strength of Ne under fast compression. During the postramp plateaus, MgO pressures continued to increase, highlighting the effect of compression rate on the time required for the coupled mechanical DAC system to reach equilibrium. Under cyclic loading, we observe phase shifts between oscillating differential stresses and volume strains in Ne, possibly indicating that viscoelastic/-plastic behavior of either Ne or the gasket material contributed to the overall response. We found this effect more pronounced for lower frequencies and larger cycling amplitudes. The findings presented in this paper improve our understanding of material behavior during dynamic loading in the DAC and provide reference data and methodology for studies of complex materials and loading paths.

Hexagonal boron nitride (hBN) spin defects offer transformative potential for quantum sensing through atomic-scale proximity to target samples, yet their performance is fundamentally limited by rapid coherence loss. While magnetic noise mechanisms have been extensively studied, another critical influence from surface electric field noise remains unexplored in hBN systems. Here, we employ shallow boron vacancies $\left(V_B^{-}\right)$ as in situ quantum sensors using the double-quantum relaxation method, demonstrating a depth-related power-law frequency dependence of the noise. The relaxation rate is independent of implantation fluence, and shows a noticeable rise as the temperature increases from 296 K to 453 K, evidencing a thermal contribution. Using glycerol treatment to selectively suppress electric field fluctuations via its high dielectric constant, we effectively reduce the electric field noise intensity by more than 30%, and quantify the lower bound of vertical surface charge noise as $E_{\perp }^{\mathrm{RMS}}$ about $9.1\times {10}^6$ V/m. Our work provides the direct quantification of hBN surface electric field noise.

Magnetocrystalline anisotropy in iron garnets originates from the interplay between lattice symmetry, cation site preference, and spin-orbit coupling mediated by oxygen. We develop a dual order parameter framework that quantitatively connects site-selective occupation of inequivalent dodecahedral ($24c$) sublattices to the magnetic anisotropy energy in Bi substituted yttrium iron garnet (Bi:YIG). We introduce a site-order parameter ${\eta }_{\text{so}}$ (sublattice imbalance between $\alpha$ and $\beta$ within $24c$) and a composition parameter ${\eta }_{\text{co}}$ (total Bi fraction on $24c$) and use density-functional theory across 13 representative $({\eta }_{\text{so}},{\eta }_{\text{co}})$ states. $K({\eta }_{\text{so}},{\eta }_{\text{co}})$ obeys a compact Landau-type expansion dominated by a large odd-in-${\eta }_{\text{so}}$ linear term and a weaker even-in-${\eta }_{\text{so}}$ curvature. The fitted map yields an analytic switching boundary $K=0$ in the $({\eta }_{\text{so}},{\eta }_{\text{co}})$ plane and order-resolved three-dimensional surfaces and weight maps that make the hierarchy (linear $\gg$ quadratic $\gg$ cubic) explicit. This unified framework rationalizes growth-induced anisotropy trends in Bi:YIG and suggests actionable routes for engineering uniaxial anisotropy via controlled $A$-sublattice ordering.

V-based kagome metals exhibit a unique lattice geometry that can give rise to exotic electronic and magnetic phenomena, making them an ideal platform to study the interplay of topology and magnetism. We present a combined thermodynamic and muon spin relaxation $\left(\mu \mathrm{SR}\right)$ investigation of single-crystal ${R\mathrm{V}}_6{\mathrm{Sn}}_6$ $(R=\text{Tb}, \mathrm{Dy}, \mathrm{Ho}, \mathrm{Er})$ compounds, focusing on their low-temperature magnetic behavior. Heat-capacity and $\mu \mathrm{SR}$ measurements reveal distinct magnetic phase transitions below 4 K, confirming the emergence of long-range magnetic order in all compounds studied. The $\mu \mathrm{SR}$ results further indicate persistent spin fluctuations within the magnetically ordered state down to 50 mK, reflected in reduced ordered moments obtained from a hyperfine analysis of the heat-capacity measurements. These findings uncover the coexistence of static and dynamic magnetism in V-based kagome metals and emphasizing the key role of $4f$-electron anisotropy in shaping their magnetic ground states. Compared with the Mn-based $R{\mathrm{Mn}}_6{\mathrm{Sn}}_6$ analogs, our results highlight the unique magnetism arising from the decoupled rare-earth sublattice and its interplay with the nonmagnetic V kagome network.

The metallic systems MnSi and ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ are known to feature a generic magnetic phase diagram primarily determined by the isotropic exchange and Dzyaloshinskii-Moriya interactions. However, additional weaker anisotropies, lowest in the hierarchy of energy scales, play a crucial role: they determine the relative order of phases in the phase diagram and may even enable skyrmion stability far below the ordering temperature. Among cubic B20 helimagnets, the insulator ${\mathrm{Cu}}_2{\mathrm{OSeO}}_3$ is currently the only known example exhibiting a low-temperature, anisotropy-induced skyrmion pocket. In this manuscript, we present a systematic study of cubic magnetocrystalline anisotropy by means of angle-resolved SQUID magnetization measurements in MnSi and ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ $(0.08\le x\le 0.70)$ single crystals and provide quantitative values of the anisotropy constants. For ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$, the cubic anisotropy is found to be strongly dependent on the Co concentration $x$. From a theoretical point of view, for low Co concentrations $(x\sim 0.10)$, the anisotropy is expected to be sufficiently strong to stabilize a low-temperature skyrmion lattice. Therefore, ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ may represent the first chiral metallic system to exhibit a low-temperature skyrmion phase controllably stabilized by cubic anisotropy for specific directions of the magnetic field.

The ${\phi }_0$ superconductor-ferromagnet-superconductor Josephson junction exhibits unique locking phenomena under the external periodic signal when the magnetic component is taken into account. Contrary to the well-known Shapiro steps that come from the locking with the electric component, locking of the Josephson oscillations with the magnetic one results in the appearance of Buzdin steps in the current-voltage characteristic and a much more complex response of the system. These steps possess distinctive properties that are indications of their unique origins and locking mechanisms. The width of the Buzdin step oscillates with the amplitude of the magnetic component; nevertheless, it exhibits anomalies in the Bessel-like behavior. Additionally, we perform an analytical analysis that supports the numerical results and shows that the width of the Buzdin step represents a product of two Bessel functions. Investigation of the effects that simultaneously appear in the magnetic subsystem reveals the presence of destructive interference and magnetization reorientation that accompany the occurrence of Buzdin steps.

The functional derivative of the superconducting critical temperature $T_c$ with respect to the Eliashberg electron-phonon spectral function $\delta T_c/\delta {\alpha }^{2}F\left(\omega \right)$ is commonly used as a diagnostic tool to identify the phonon-frequency regions that most effectively enhance $T_c$. In this work, the explicit effect of temperature on the calculation of $\delta T_c/\delta {\alpha }^{2}F\left(\omega \right)$ is investigated within the isotropic Eliashberg formalism for the conventional high-$T_c$ superconductors ${\mathrm{H}}_3\mathrm{S}$ and ${\mathrm{D}}_3\mathrm{S}$ over the pressure ranges in which their $T_c$ have been measured. The results show that the functional derivative is strongly temperature dependent and, for every pressure in both systems, exhibits a robust local minimum in the $\omega \text{−}T$ landscape, characterized by $({\omega }_L,T_L)$. This characteristic point corresponds to a thermal reference condition where $T_c$ is least sensitive to redistributions of spectral weight in ${\alpha }^{2}F\left(\omega \right)$. The extracted ${\omega }_L$ correlates approximately linearly with ${\omega }_{ln}$, while the reduced ratio ${\omega }_L/\left(k_B{T}_L\right)$ correlates with ${\lambda }^{-1}$ and clusters around 7, placing $({\omega }_L,T_L)$ close to the canonical optimal-frequency scale ${\omega }_{\mathrm{opt}}\sim 7$–$8k_B{T}_c$. Motivated by these scalings, an empirical relation (mapping) is proposed that establishes a correlation between the experimental critical temperature $T_c$ and characteristic quantities extracted from the temperature-dependent functional response $({\omega }_L,T_L,\lambda )$. Over the explored pressure ranges, the resulting estimates reproduce the experimental $T_c$ values with absolute errors of 0.1–4.9 K (mean absolute error of 2.56 K). While the mapping is empirical and has been validated only within the closely related ${\mathrm{H}}_3\mathrm{S}/{\mathrm{D}}_3\mathrm{S}$ family and an isotropic treatment, the systematic behavior with pressure and isotopic substitution suggests that the identified local minimum is a robust feature of the functional derivative, motivating broader tests in other electron-phonon superconductors, including anisotropic and multiband systems.

Heavy fermion superconductors often display upper critical fields that exceed the conventional Pauli paramagnetic limit, indicating that strong correlations and hybridized quasiparticle bands play an essential role in the paramagnetic pair-breaking process. Within the two-dimensional Kondo-Heisenberg model, we perform a self-consistent mean-field analysis of spin-singlet $s$-, extended-$s$-, and $d$-wave pairing under Zeeman fields and compute the critical field $B_c$, transition temperature $T_c$, and Clogston-Chandrasekhar ratio $r_{\mathrm{CC}}$. We find that $r_{\mathrm{CC}}$ increases sharply as the conduction filling approaches half filling. This enhancement arises from the weakly dispersive region of the lower hybridized band, where the strongly reduced Fermi velocity diminishes the normal-state paramagnetic energy and stabilizes superconductivity. At fixed filling, the distinct $J_H$ dependences among the three pairing channels reflect the sensitivity of Pauli limiting to both band curvature and the structure of the order parameter. These results provide microscopic evidence that proximity to a near-flat hybridized band offers a robust route to enhanced Pauli-limiting fields in heavy fermion superconductors.

Recent investigations have shown that higher-order topological solitonic insulators can be created in nonlinear media. However, current discussions on higher-order topological solitons only focus on Euclidean spaces. In this work, we theoretically propose and numerically demonstrate the construction of higher-order topological solitons in engineered hyperbolic lattices, which are regular tessellations in non-Euclidean space with a constant negative curvature. In particular, two types of hyperbolic lattices, {4, 5} and {8, 3}, are applied to design higher-order topological solitonic insulators. We demonstrate that for both types of lattices, higher-order topological solitons can bifurcate from linear corner states under either self-focusing or self-defocusing nonlinear conditions, with their localization being controllable by the initial input power. We also observe that the rotational symmetry of these topological solitons remains unaffected by variations in the initial input power. Our work theoretically extends higher-order topological soliton insulators to non-Euclidean space, breaking through the limitation in traditional Euclidean space where only topological solitons with threefold, fourfold, and sixfold rotational symmetries can be realized. This enables the realization of topological solitons with higherfold rotational symmetries. It provides a theoretical foundation for the design of experimentally feasible platforms for higher-order hyperbolic topological solitonic insulators, and is anticipated to have potential applications in designing highly efficient soliton devices with strong robustness.

Achieving electrical control of magnetic states is highly pursued for next-generation nonvolatile memory, yet it remains a significant challenge in spintronic devices. In this study, we propose a homojunction-based strategy to realize fully electrical control of spin valve. We demonstrate that the multiferroic α-MXenes ${\mathrm{Cr}}_2{\mathrm{CO}}_2$ and ${\mathrm{Mn}}_2{\mathrm{CO}}_2$ exhibit not only ferromagnetic half-metallicity with high Curie temperatures but also a moderate ferroelectric dipole moment with feasible polarization-switching barriers. Owing to the robust magnetoelectric coupling effect, the ferromagnetic and antiferromagnetic states in ${\mathrm{Cr}}_2{\mathrm{CO}}_2/{\mathrm{Cr}}_2{\mathrm{CO}}_2$ and ${\mathrm{Mn}}_2{\mathrm{CO}}_2/{\mathrm{Mn}}_2{\mathrm{CO}}_2$ homojunctions can be toggled by switching their own polarization directions. To elucidate the underlying electric control mechanism, we constructed two spin valve devices with the following layered structures: 1T-${\mathrm{MoS}}_2/{\mathrm{Cr}}_2{\mathrm{CO}}_2/{\mathrm{Cr}}_2{\mathrm{CO}}_2$/1T-${\mathrm{MoS}}_2$ and 1T-${\mathrm{MoS}}_2/{\mathrm{Mn}}_2{\mathrm{CO}}_2/{\mathrm{Mn}}_2{\mathrm{CO}}_2$/1T-${\mathrm{MoS}}_2$. Remarkably, these spin valves exhibit engineered interfacial contacts and achieve a fully electrically controlled magnetoresistance ratio (MR) of $\sim {10}^6\%$, benefiting from the distinctive junction properties and precisely tailored architecture. This study not only provides a perspective for the development of electrical writing and magnetic reading nonvolatile memory but also provides insights for designing other advanced spintronic devices.

The generation of attosecond pulses from higher-order harmonics is an essential milestone toward enabling time-resolved spectroscopy of electronic processes in matter on the attosecond timescale. The avenue for high-harmonic generation from solids has proliferated since its discovery a decade ago. However, isolated attosecond pulse generation from solids remains scarce. We report a theoretical proposal that leverages Weyl semimetals for highly efficient attosecond pulse generation in the far-ultraviolet region. The generation of isolated attosecond pulses from Weyl semimetals is achieved using two-color laser pulses, which generate a broad higher-harmonic plateau ranging from 3 to 11 eV. Attosecond pulses with comparable durations – spanning approximately 500 to 900 as – are generated in both collinear and orthogonal configurations of the two-color fields. The strength and duration of the attosecond pulses can be optimized by tailoring the polarization direction and relative strength of the two-color field.

We have measured second-order Raman scattering in high-quality monoisotopic $h$-BN crystals for all possible boron and nitrogen isotope combinations. The second-order spectra are dominated by phonon combinations and are well aligned with density-functional perturbation-theory calculations of the two-phonon density of states. The isotopic shifts are well described by second-order perturbation of the dynamical matrix. The analysis of the Raman spectra of the monoisotopic samples and their isotopic shifts allows us to unambiguously assign the second-order peaks and to determine phonon frequencies at $M$ and $K$ zone-edge points, as well as on the $T$ line. This study demonstrates the usefulness of Raman spectroscopy as a tool for probing the frequencies of zone-edge phonons. These play a prominent role in the phonon-assisted emission in $h$-BN. The study also serves as a stringent test of the density-functional theory calculations commonly used to estimate these frequencies.

Orbital magnetization (OM) in Sierpinski carpet (SC) and triangle (ST) fractal is theoretically investigated by using Haldane model as a prototypical example. The OM calculation is performed following two distinct approaches; employing the definition and local markers formalism. Both methods coincide for all systems analyzed. For the SC, higher fractal generations create a dense set of edge states, resulting in a staircase profile, leading to fluctuations in the magnetization as a function of the chemical potential. In contrast, the ST self-similarity produces distinct fractal-induced spectral gaps, which manifest as constant plateaus in the magnetization. The STs exhibit a pronounced sensitivity to edge terminations. Our results reveal how quantum confinement in fractal structures affects the electronic orbital angular momentum, pointing to possible pathways for exploring novel orbitronics in systems with complex geometries.

Magnetic exchange interactions (MEIs) in kagome magnets exhibit rich features due to the interplay of charge, spin, orbital and lattice degrees of freedom, giving rise to a variety of exotic quantum states. Through first-principles calculations, we systematically investigate the MEIs in kagome antiferromagnets FeGe and FeSn. While the antiferromagnetic order originates from the interlayer coupling between neighboring kagome layers, Fe atoms within each kagome layer couple ferromagnetically, driven by the competition between ferromagnetically favorable direct MEIs and antiferromagnetically favorable Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. The stronger direct MEIs but weaker RKKY interactions in FeGe result in a substantially higher Néel temperature with respect to FeSn. Interestingly, the nearest neighboring exchange energy in both materials approximately linearly depends on the Fe-Fe bond length, so that moderate compressive strain can significantly enhance their Néel temperatures.