The magnetic proximity effect (MPE), which describes a magnetic response from a heavy metal layer as a result of an adjacent magnetic layer, plays an important role in the behavior of heavy-metal/ferro- or ferrimagnet thin film heterostructures. However, in the case of heavy-metal/rare-earth iron garnet bilayers, the presence and magnitude of the MPE has been debated. We previously reported an MPE in a Pt/dysprosium iron garnet (DyIG) heterostructure where the two layers were grown without breaking vacuum, finding that the magnetic moment present in the Pt layer scales with the magnitude of the DyIG moment and varies nonmonotonically through the DyIG compensation temperature. However, the origin of the magnetic signal from the Pt layer was not identified. In contrast, Pt/DyIG grown with a vacuum break did not exhibit an MPE. Here we investigate the origin of the magnetic moment in the Pt layer using x-ray absorption spectroscopy, x-ray circular dichroism, composition mapping, and simulations of ion bombardment. The results are consistent with the presence of an intermixed Fe-Dy-Pt interfacial alloy layer formed during the growth of the Pt on the DyIG resulting in a measurable MPE.

${\mathrm{Sm}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$, a member of the rare-earth titanate pyrochlores, exhibits dipolar-octupolar antiferromagnetism below $T_N=0.35\mathrm{K}$. We observed two ferroelectric transitions at 182 ($T_{\text{FE}1}$) and 52 K ($T_{\text{FE}2}$), significantly higher than $T_N$ for ${\mathrm{Sm}}_2{\mathrm{Ti}}_{2-x}{\mathrm{V}}_x{\mathrm{O}}_7$ ($x=0,0.1$). Although the ferroelectric transition temperatures remain unchanged, the polarization value decreases with V doping. A structural transition to a polar $R3m$ rhombohedral phase from the cubic $Fd\overline{3}m$ structure occurs at $T_{\text{FE}1}$ for the pristine compound, involving a distortion in the pyrochlore lattices formed by the Sm atoms. Remarkably, linear magnetoelectric coupling is observed in both compounds, with further enhancement of magnetoelectric (ME) coupling due to magnetic V doping. The existence of magnetoelectric coupling without long-range magnetic order is of fundamental interest for advancing the understanding and development of ME coupling.

It is known that Green's functions can be expressed as continued fractions, the content at the $n\mathrm{th}$ level of the fraction is encoded in a coefficient $b_n$, which can be recursively obtained using the Lanczos algorithm. We present a theory concerning errors in approximating Green's functions using continued fractions when only the first $N$ coefficients are known exactly. Our focus lies on the stitching approximation (also known as the recursion method), wherein truncated continued fractions are completed with a sequence of coefficients for which exact solutions are available. We assume a standard conjecture about the growth of the Lanczos coefficients in chaotic many-body systems, and that the stitching approximation converges to the correct answer. Given these assumptions, we show that the rate of convergence of the stitching approximation to a Green's function depends strongly on the decay of staggered subleading terms in the Lanczos coefficients. Typically, the decay of the error term ranges from $1/\mathrm{poly}\left(N\right)$ in the best case to $1/\mathrm{poly}(logN)$ in the worst case, depending on the differentiability of the spectral function at the origin. We present different variants of this error estimate for different asymptotic behaviors of the $b_n$, and we also conjecture a relationship between the asymptotic behavior of the $b_n$'s and the smoothness of the Green's function. Lastly, with the above assumptions, we prove a formula linking the spectral function's value at the origin to a product of continued fraction coefficients, which we then apply to estimate the diffusion constant in the mixed field Ising model.

The momentum space of conventional superconductors is recently recognized to possess a quantum metric defined from the overlap of filled quasihole states at neighboring momenta. For multiband superconductors with arbitrary intraband and interband $s$-wave pairing, we elaborate that their superfluid weight in London equations is given by the momentum integration of the elements of the quantum metric times the quasiparticle energy, indicating the quantum geometric origins of the Meissner effect and vortex state. The momentum integration of the quantum metric further yields a spread of quasihole Wannier functions that characterizes the stability of the superconducting state. Our formalism allows the diamagnetic response of conventional superconductors to be mapped to individual lattice sites as a superfluid weight marker, which can incorporate the effect of disorder through self-consistently solving the Bogoliubov–de Gennes equations. Using single-band $s$-wave superconductors in two and three dimensions as examples, our marker reveals a diamagnetic current that becomes turbulent in the presence of nonmagnetic impurities, and an increase of London penetration depth by disorder that is consistent with experiments.

Bipartite entanglement entropy is one of the most useful characterizations of universal properties in a many-body quantum system. Far from equilibrium, there exist two highly effective theories describing its dynamics—the quasiparticle and membrane pictures. In this work we investigate entanglement dynamics, and these two complementary approaches, in a quantum circuit model perturbed by an impurity. In particular, we consider a dual unitary quantum circuit containing a spatially fixed, non-dual-unitary impurity gate, allowing for differing local Hilbert space dimensions to either side. We compute the entanglement entropy for both a semi-infinite and a finite subsystem within a finite distance of the impurity, comparing exact results to predictions of the effective theories. We find that for a semi-infinite subsystem, both theories agree with each other and the exact calculation. For a finite subsystem, however, both theories qualitatively differ, with the quasiparticle picture predicting a nonmonotonic growth in contrast to the membrane picture. We show that such nonmonotonic behavior can arise even in random chaotic circuits, shedding light on the range of validity of the membrane picture in such systems.

Decomposition of global properties (e.g., total energy) into local entities, as implemented in machine-learning- and neural-network-driven materials modeling, inherently introduces uncertainty due to the physically undefined nature of local properties. The validity of local decomposition constitutes an essential but still debated consideration in current studies. To address this ambiguity, we introduce a probabilistic atomic energy regularization (AER) framework designed to constrain local energy projections in machine learning interatomic potentials (MLIPs). The essence of AER is to regulate local-environment-determined atomic properties by incorporating statistically significant long-range correlations, thereby establishing a probability-based framework that selectively filters local decomposition incompatible with established correlation constraints. Beyond significantly improving decomposition robustness in regular solids, AER demonstrates excellent physical scalability as evidenced by the thermal transport simulations for $\beta \text{−}\mathrm{C}{\mathrm{u}}_{1.95}\mathrm{Se}$ with highly fluctuating local environment and higher-order nonlinearity. Our findings not only underscore the critical role of prior beliefs in MLIP development but also offer a generalized framework for resolving property decomposition controversies across data-driven machine-learning models.

The dynamical quantum phase transition (DQPT) is an important concept in nonequilibrium critical phenomena; however, its relation to the equilibrium quantum phase transition (EQPT) remains obscure. Substantial evidence has suggested that quenching across the underlying equilibrium phase boundary is neither a sufficient nor a necessary condition for the existence of the DQPT. In this work, we give a necessary and sufficient condition for the occurrence of DQPTs in two-band systems by introducing the quench fidelity, which is defined as the fidelity between the ground-state wave functions of the prequench and postquench Hamiltonian, and elaborate it by taking the one-dimensional anisotropic XY model as an example. The relation between EQPTs and DQPTs is analyzed in detail in terms of the quench fidelity.

$d$-wave altermagnets have the magnetic octupole as their primary order parameter. A recent study [Han et al., Phys. Rev. Lett. 135, 076705 (2025)] demonstrated that magnetic octupole current can induce Néel vector dynamics. Therefore, identifying materials that can efficiently generate a magnetic octupole current is essential. In this paper, we investigate the magnetic octupole Hall effect in $4d$ and $5d$ transition metals. By employing atomic magnetic octupole operators, we calculate the magnetic octupole Hall conductivity using first-principles calculations. We also explore the microscopic origin of the magnetic octupole Hall effect and find that it results from the combined effect of orbital texture and spin-orbit coupling. Additionally, we compare the spin Hall conductivity with magnetic octupole Hall conductivity across various materials and identify those that are optimal for observing magnetic octupole physics. We also discuss potential applications arising from the magnetic octupole Hall effect. Our work serves as a valuable reference for identifying materials suitable for studying magnetic octupole physics.

We theoretically investigate the ground states of a chiral magnet with a square anisotropy and show that it supports domain wall networks as stable ground states. A domain wall junction in the domain wall network turns out to be a skyrmion with half topological charge and, therefore, the found domain wall network has a second topological nature, a skyrmion crystal. More specifically, we present a ground-state phase diagram of a chiral magnet with varying anisotropy parameters consisting of skyrmion lattices, chiral soliton lattices, and ferromagnetic states. In the presence of the square anisotropy, the skyrmion crystal forms a domain wall network. The size of domains in the domain wall network is shown to be tunable by an external magnetic field, offering a way to realize experimentally detectable domain wall networks.

The emergent magnetic phase of altermagnetism supports nonrelativistic spin currents under an external electric field, even in the absence of net magnetization—a phenomenon known as the spin-splitter effect. Traditionally, this effect has been attributed to spin-dependent anisotropies in the electronic band structure or electron group velocities. However, the role of spin-dependent anisotropies in scattering processes, particularly electron-phonon interactions, has been largely overlooked. In this study, we highlight the crucial influence of electron-phonon scattering on both the efficiency and direction of charge-to-spin conversion in altermagnetic materials. When the anisotropy of electron-phonon scattering aligns with that of the electron group velocities, the charge-spin conversion is significantly enhanced. Conversely, a mismatch in their anisotropies can suppress the conversion efficiency—or even reverse the direction of the generated spin current. Our first-principles calculations demonstrate that phonons in real materials can either enhance, suppress, or reverse the spin-splitter effect depending on their interaction anisotropies. These findings underscore the importance of understanding and engineering scattering mechanisms to optimize the performance of altermagnet-based spintronic devices.

Resonant inelastic x-ray scattering (RIXS) is a powerful tool for probing the ground-state electronic configurations of actinide materials. However, in certain metallic uranium compounds, RIXS fails to detect excitations from the ground-state multiplet. This absence is attributed to strong hybridization between uranium $5f$ electrons and conduction electrons. In the present study, we extend RIXS investigations to a $16\mu \mathrm{g}$ sample of the metallic compound ${\mathrm{AmFe}}_2$, marking an experiment at the $M_{4,5}$ edges of a transuranium material. Americium in ${\mathrm{AmFe}}_2$ adopts a trivalent (${\mathrm{Am}}^{3+}$) state with a $5f^6$ electronic configuration having a $J$ = 0 ground state, with the $5f$ states located approximately 3 eV below $E_F$. The RIXS spectra exhibit well-resolved features that are in good agreement with theory. The localized nature of the $5f$ electrons in ${\mathrm{AmFe}}_2$ permits the observation of multiplet excitations despite its metallic character. These observations extend our understanding of RIXS in actinide systems.

This paper presents a complex band analysis of one-dimensional (1D) square and high-root topological insulators (HRTIs). We show that edge-state bands of HRTIs are sliced sections of impurity bands of a uniform tight-binding chain. A simplified topological characterization of HRTIs with generalized boundary conditions is carried out based on the existence of edge-state bands in the infinite HRTI and the restrictions imposed by the boundary conditions. Edge states in finite or semi-infinite 1D HRTIs are shown to be a subset of evanescent states of the infinite system and mapped onto impurity states of the uniform chain with effective energy-dependent edge potentials. The latter result allows the determination of the edge-state levels without needing the diagonalization of real space or bulk Hamiltonians.

We simulate the non-Abelian exchange of Majorana zero modes (MZMs) on a quantum computer. Rather than utilizing MZMs at the boundaries of quantum Ising chains, which are typically represented as nonlocal operators on a quantum computer, using a Kitaev lattice allows us to exploit a local representation of MZMs. We detail the protocol for braiding two and four MZMs in terms of a spin Hamiltonian, i.e. physical qubit Hamiltonian. Projecting this onto a subspace of states, we extract an effective Hamiltonian which drives a non-Abelian Berry phase. Using several approximations, we construct a set of gates which mimics this accumulation of non-Abelian phase and process this construction on a quantum computer. For two and four MZMs, we realize braiding fidelities of approximately 85 and 47%, respectively.

Metallic antiferromagnets are essential for efficient spintronic applications due to their fast switching and high mobility, yet room-temperature metallic antiferromagnets are rare. Here, we investigate ${\mathrm{YbMn}}_2{\mathrm{Ge}}_2$, a room-temperature antiferromagnet, and establish it as an exfoliable layered metal with altermagnetic surface states. Using multiorbital Hubbard model calculations, we reveal that its robust metallic antiferromagnetic ordering is stabilized by electronic correlations and a partially nested Fermi surface. Furthermore, we show that ${\mathrm{YbMn}}_2{\mathrm{Ge}}_2$ hosts symmetry-protected topological Dirac crossings, connecting unique even-order spin-polarized surface states with parabolic and inverted Mexican-hat-like dispersion. Our findings position ${\mathrm{YbMn}}_2{\mathrm{Ge}}_2$ as a promising platform for exploring the interplay of correlation, topology, and surface altermagnetism of layered antiferromagnets.

Positive terahertz photoconductivity is observed at room temperature in CdHgTe thin films with different Cd contents. We show that electron gas heating caused by Drude-like absorption results in positive photoconductivity because of the interband activation mechanism specific for undoped narrow-gap semiconductors and semimetals. Applying intense terahertz radiation, we observed that the photoconductivity saturates at high intensities, which was found to be caused by absorption bleaching. Both the magnitude of the photoconductivity and the saturation intensity are shown to exhibit an exponential dependence on the hydrostatic pressure. We show that this is a consequence of the fact that both phenomena are controlled by the ratio of energy and momentum relaxation times.

Crystalline graphene heterostructures, namely, Bernal bilayer graphene (BBLG) and rhombohedral trilayer graphene (RTLG), for example, subject to perpendicular electric displacement fields, display a rich confluence of competing orders, resulting in a valley-degenerate, spin-polarized half-metal at moderate doping, and a spin- and valley-polarized (nondegenerate) quarter-metal at lower doping. Here we show that such a quarter-metal can be susceptible toward the nucleation of a unique spin- and valley-polarized superconducting ground state, accommodating odd-parity (dominantly $p$ wave in BBLG and $f$ wave in RTLG) interlayer Cooper pairs that break the translational symmetry, giving rise to a Kekule (in BBLG) or columnar (in RTLG) pair density wave. Due to the trigonal warping in the normal state, the superconducting ground state produces threefold rotationally symmetric isolated Fermi rings of normal fermions, which can manifest via linear in temperature scaling of the specific heat. We present scaling of the zero-temperature pairing amplitude and the transition temperature of such pair density wave in the presence of trigonally warped disconnected, annular, and simply connected Fermi rings in the normal state, subject to an effective attractive interaction within a mean-field approximation.

The kagome materials with tunable magnetism and nontrivial topological state are appealing in both the theoretical study and the applications, such as the spintronics device and topological quantum calculations. In this work, we study the magnetism and topological states of the shandite kagome materials family $M_3{X}_2{\mathrm{S}}_2(M=\mathrm{Rh},\mathrm{Ni};X=\mathrm{Sn},\mathrm{Pb})$ comprehensively. Under the nonmagnetic states, ${\mathrm{Rh}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$ is a strong topological insulator after doping one electron in the primitive cell and ${\mathrm{Rh}}_3{\mathrm{Pb}}_2{\mathrm{S}}_2$ is the Dirac semimetal. ${\mathrm{Rh}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$ has flat bands and a sharp density of state peak near the Fermi level, which induces itinerant ferromagnetism. In the ferromagnetic state, ${\mathrm{Rh}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$ shows a Weyl semimetal phase and an axion insulator phase under different occupations. Due to the different hybridization between $d$ orbitals of Rh and $s$ orbitals of Sn/Pb, the isomorphic material ${\mathrm{Rh}}_3{\mathrm{Pb}}_2{\mathrm{S}}_2$ has no magnetic order, which is different from that of ${\mathrm{Rh}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$. Meanwhile, ${\mathrm{Ni}}_3{\mathrm{Pb}}_2{\mathrm{S}}_2$ has three more electrons in the primitive cell and no magnetization in our calculations. It shows a weak topological insulator state. Our work reveals the magnetism and nontrivial topological phases in the shandite kagome materials family $M_3{X}_2{\mathrm{S}}_2(M=\mathrm{Rh},\mathrm{Ni};X=\mathrm{Sn},\mathrm{Pb})$. The tunable magnetism and topological states also provide a material platform for the further study of novel physical phenomena related to the magnetic nontrivial topological properties and further applications.

We investigate Kondo physics in a quantum dot side coupled to a Majorana zero mode, where the Majorana coupling induces both spin and charge fluctuations that determine low-energy behavior. Using a wave-function-based Schrieffer-Wolff transformation combined with numerical renormalization group calculations, we discover an $S{U}_L\left(2\right)$ spin-charge-entangled Kondo state, in which conduction electrons screen the spin-charge-entangled degrees of freedom of the Majorana-quantum dot subsystem. We show that the parity degeneracy of this state gives rise to spin-resolved Andreev-normal boundary conditions, resulting in non-Fermi-liquid behavior. Density matrix renormalization group simulations directly resolve a hallmark of these boundary conditions—a subleading even-odd effect in the screening cloud. Our framework bridges strongly correlated and topological phenomena, and naturally extends to ${\mathbb{Z}}_N$ parafermions and $SU\left(N\right)$ Kondo systems.