This study reports a theoretical framework that combines the auxiliary coherent potential approximation with dynamical mean-field theory (ACPA-DMFT) to study strongly correlated and disordered electronic systems with both diagonal and off-diagonal disorders. In this method, by introducing an auxiliary coupling space with extended local degree of freedom, the diagonal and off-diagonal disorder are treated in a unified and self-consistent framework of coherent potential approximation, within which the dynamical mean-field theory is naturally combined to handle the strongly correlated Anderson-Hubbard model. Using this approach, we compute Matsubara Green's functions for a simple cubic lattice at finite temperature and derive impurity spectral functions through the maximum entropy method. Our results reveal the critical influence of off-diagonal disorder on Mott-type metal-insulator transitions. Specifically, a reentrant phenomenon is identified, wherein the system transitions between insulating and metallic states under varying interaction strengths. The ACPA-DMFT method provides an efficient and robust computational approach for exploring the intricate interplay between disorder and strong correlations.

MXenes, composed of transition metal layers with various surface passivation groups, exhibit diverse magnetic and electron transport properties essential for miniaturized spintronic devices. Through density functional theory calculations, we reveal that the electronic properties of ${\mathrm{Mn}}_2\mathrm{NO}T$ $(T=\mathrm{O},\mathrm{F},\mathrm{OH},\mathrm{Cl})$ MXenes, i.e., half-metallicity and semiconductivity, are determined by the energy-level separation between two side Mn atoms arising from the distinctive two-surface passivation, in contrast to other typical 2D magnetic materials like transition metal dichalcogenides that are determined by the local metallic atom coordination symmetry. The separation degree of energy levels decides the electron configuration of Mn $3d$ orbitals and the Fermi-level position, thereby determining the half-metallicity or semiconductivity. This mechanism enables dynamic control methods for tuning electronic and magnetic properties. For instance, charge (electron or hole) doping and applying uniaxial strain can drive transitions between semiconductor and half-metal states by modulating the Mn energy levels, Mn-N electrostatic potential, and Mn $3d$ orbitals filling at two surface sides. Our findings reveal the physical origins of MXenes' electromagnetic properties and offer strategies for designing tunable and highly integrated spintronic devices.

Exchangeless braiding of Majorana modes is studied in minimal networks of weakly hybridized Kitaev chains of finite length using a rigorous many-body framework. In particular, for two coupled chains it is shown that exchangeless braiding is achieved by $2\pi$ rotations of the phase $\varphi$ of the superconducting order parameter of one of the chains. This braiding protocol is verified by the numerical calculation of the non-Abelian Wilczek-Zee phase of the low-energy many-body subspaces ${\mathcal{H}}_0\left(\varphi \right)$ based on the Bertsch-Robledo ground-state overlap formula. In the parameter space spanned by the total chain length, the strength of the weak hybridization connecting the chains, and the on-site potential, we identify two regions with different braiding outcomes, i.e., a projective ${\sigma }_x$ gate and a projective ${\sigma }_z$-gate phase. The transition between these phases is a continuous crossover, the location of which is reliably given by a simple four-Majorana mode model. This demonstrates the resilience of the anyonic properties of the Majorana modes against finite-size effects and weak links between Kitaev chains.

Two-dimensional (2D) van der Waals (vdW) ferroelectrics with robust polarization hold great promise for next-generation nanoscale electronics. While interlayer sliding-induced symmetry breaking has been extensively studied, the polarization alignment between layers has received less attention. Here, by means of first-principles calculations, we study the interlayer polarization alignment in three representative bilayer vdW ferroelectrics, ${\mathrm{In}}_2{\mathrm{Se}}_3, {\mathrm{CuInP}}_2{\mathrm{S}}_6$, and SnSe. Surprisingly, antiparallel alignments, tail-to-tail for ${\mathrm{In}}_2{\mathrm{Se}}_3$, head-to-head for ${\mathrm{CuInP}}_2{\mathrm{S}}_6$, and interlayer antiparallel for SnSe, emerge as the lowest-energy configurations. Contrary to conventional bulk ferroelectrics, where dipole-dipole electrostatic energy dominates, we find that vdW energy governs the interlayer polarization alignment in out-of-plane (OP) vdW ferroelectrics (${\mathrm{In}}_2{\mathrm{Se}}_3$ and ${\mathrm{CuInP}}_2{\mathrm{S}}_6$), while dipole-dipole interactions dictate for in-plane (IP) ferroelectric SnSe. This distinction arises from the unique atomic arrangement near the vdW gap in OP systems, which lowers the vdW energy in antiparallel configurations. The existence of these antiparallel interlayer alignments opens up possibilities for multiple accessible states, offering exciting opportunities for high-density miniaturized memory devices.

We show that the integer quantum Hall transition in a disordered nanowire with orbital momentum-space texture connected to four terminals is accompanied by an orbital Hall transition. We applied a multifractal detrended fluctuation analysis and found that both conductance fluctuations in the integer quantum Hall transition (IQHT) and orbital-conductance fluctuations in the orbital Hall transition (OHT) display multifractal behavior. We argue that this multifractality is primarily related to disorder, which gives rise to the strong fluctuations that are fingerprints of IQHT and OHT, but is also a consequence of the fact that the nanowire has finite size, which causes a weakening of the multifractality in a certain range of values of disorder strength followed by a new regime of increasing multifractality with increasing disorder strength. Furthermore, our findings indicate that OHT can bring novel insights to future IQHT analysis.

The polar magnet ${\mathrm{Ni}}_3{\mathrm{TeO}}_6$ is known for its large magnetoelectric (ME) effect at cryogenic temperatures ($\sim 52$ K) and in high magnetic fields ($\sim 9$ T). Substitution of Ni with Mn could be an effective way to enhance magnetic ordering temperature and reduce critical magnetic fields. In this work, we have investigated the anisotropic ME effect in Mn-substituted polar magnet ${\mathrm{Ni}}_2\mathrm{MnTe}{\mathrm{O}}_6$ through measurements of the temperature and magnetic field dependence of the dynamic ME coefficient (${\alpha }_{\mathrm{E}}=\mathrm{d}E/\mathrm{d}H)$ and the dielectric permittivity (${\varepsilon }_{\mathrm{r}}$) on a single-crystal sample. It is found that ${\alpha }_{\mathrm{E}}$ exhibits pronounced peaks/dips whenever a magnetic phase transition is induced by either temperature or magnetic field. The maximum dynamic ME effect occurs at 45 K in $H\sim 3.95$ T and at 68 K in $H\sim 3.4$ T for $H//c$ axis and $ab$ plane, respectively. The obtained phase diagrams illustrate distinct regimes with dominant ME effect at phase boundaries. Our study demonstrates that a significant dynamic ME effect comparable to multiferroic composites can be expected in single-phase polar magnets. Moreover, it is proposed that the dynamic ME coefficient ${\alpha }_{\mathrm{E}}$ could act as a sensitive probe to detect subtle phase transitions in insulating magnets.

Achieving direct and large magnetoelectric (ME) coupling in single-phase multiferroic at room temperature is a challenging task for physicists and material engineers as type I multiferroics have independent ferroic orders and type II multiferroics exhibit fairly weak polarization due to spin-orbit interaction at very low temperatures. Here, we show that by lowering the symmetry of $\mathrm{BiFe}{\mathrm{O}}_3$ via the oxygen octahedron distortion and proper tilting it is possible to induce the spontaneous polarization from B-site Fe ions and a partial reduction of $\mathrm{F}{\mathrm{e}}^{3+}$ into $\mathrm{F}{\mathrm{e}}^{2+}$ results in ferromagnetic super-exchange $\mathrm{F}{\mathrm{e}}^{3+}-\mathrm{O}-\mathrm{F}{\mathrm{e}}^{2+}$ interactions, providing room temperature multiferroics that have the same origin for both ferroelectricity and ferromagnetism. The dynamic room-temperature ME effect which originates from the intrinsic ME interaction between magnetic moments and ferroelectric polarization is evidenced by the resonant behavior of the complex dielectric permittivity and complex magnetic permeability at microwaves. A striking interplay between ferroelectricity and magnetism is demonstrated by the electric polarization reversal and magnetization reversal, both actuated by applied magnetic and electric fields. The room-temperature multiferroic material combines the advantages of type I multiferroics and type II multiferroics, thus providing great potential for construction of low-energy nonvolatile magnetoelectric storages and sensors.

The efficient detection of the magnetism in 2D antiferromagnetic (AFM) insulators is crucial for the advancement of 2D AFM spintronics and remains a challenging problem. In this paper, we introduce the magnon nonlinear Hall current, a second-order Hall response of collective spin excitations in ordered magnets, as a probe for 2D layered AFM insulators. We theoretically demonstrate that such the nonlinear Hall response is intrinsically coupled to the underlying spin configuration. In particular, it exhibits a pronounced layer dependence in layered antiferromagnets, enabling direct characterization of the nature and strength of interlayer magnetic coupling in multilayer AFM insulators. Furthermore, in contrast to the weak linear Hall response, even a slight external field can significantly enhance the second-order Hall response of magnons. This field-induced giant nonlinear Hall response, along with its reversible nature, effectively addresses the inherent limitations of 2D AFM insulators with zero magnetization and weak field sensitivity, broadening their application potential.

In quantum physics, even simple data with a well-defined structure at the wave-function level can be characterized by extremely complex correlations between its constituent elements. The inherent nonlocality of the quantum correlations generally prevents one from providing their simple and transparent interpretation, which also remains a challenging problem for advanced classical techniques that approximate quantum states with neural networks. Here we show that monitoring the neural network weight space while learning quantum statistics from measurements allows us to develop physical intuition about complex multipartite patterns and thus helps to construct more effective classical representations of the wave functions. In particular, we observe the formation of distinct global convolutional structures, receptive fields in the hidden layer of the restricted Boltzmann machine within the neural quantum tomography of the highly entangled Dicke states. On this basis we propose an exact two-parameter classical representation not only for a specific quantum wave function, but for the whole family of $N$-qubit Dicke states of different entanglement. Our findings suggest a fresh look at constructing convolutional neural networks for processing data with nonlocal patterns and may pave the way for developing exact learning-based representations of entangled quantum states.

We study the ground-state critical behavior of the Bose-Hubbard model in two and three dimensions at large filling factors, using the quantum spherical model as the primary analytical framework. The scaling properties of the critical hopping amplitude $t$ at the quantum phase transition from the Mott insulator to the superfluid phase are analyzed in detail. We derive the scaling behavior of $t$ as a function of interaction strength and chemical potential and validate our results through comparisons with the process chain approach, demonstrating consistency and robustness across methods. Our findings reveal dimensional dependencies and significant deviations in the scaling behavior at high filling factors compared to low filling regimes, underscoring the impact of quantum fluctuations in these systems. The results offer a comprehensive understanding of the universality classes and phase diagram structures of the Bose-Hubbard model at high occupancies, contributing to the broader study of strongly correlated bosonic systems.

We study the Josephson effects in the superconductor/two-dimensional Weyl nodal line semimetal/superconductor junctions using the Green's function method. When the Rashba spin-orbit coupling and an external magnetic field coexist in the semimetal, the symmetries protecting the reciprocity of supercurrent can be broken and the Josephson diode effect with the nonreciprocity of supercurrent can be realized. A high efficiency exceeding $40\%$ can be achieved with the experimentally accessible values of the magnetic field and the Rashba spin-orbit coupling. The diode efficiency can be easily controlled by the direction and magnitude of the field and the strength of the spin-orbit coupling. When the spin-orbit coupling is absent or the external field is absent, the Josephson diode effect vanishes but the current-phase difference relations still show strong dependence on the field or the coupling. The tunable $0\text{−}\pi$ transition and the switch effect of supercurrent in the junctions can be formed if the direction of the field is rotated or the magnitude of the field and the strength of the coupling are changed. The obtained Josephson diode effect, the $0\text{−}\pi$ transition and the switch effect of supercurrent are helpful in the design of the quantum devices based on nodal line semimetals.

The heavy-fermion compound ${\mathrm{UTe}}_2$ is a candidate for hosting intrinsic spin-triplet superconductivity. At present, however, the type of triplet Cooper pairing realized in ${\mathrm{UTe}}_2$ remains unknown, which calls for further experimental and theoretical investigations. In this paper, we develop a microscopic minimal model for the superconducting phases of ${\mathrm{UTe}}_2$ based on recent findings in the description of its low-energy normal state electronic properties. We apply the resulting theoretical model to extract the nodal gap properties of the allowed superconducting ground states, and determine their associated topological surface states on the experimentally relevant (0-11) cleave plane. We find that the Fermi surface of ${\mathrm{UTe}}_2$ enforces additional point nodes in excess to the point nodes imposed by symmetry, which may reconcile several experiments seemingly in conflict with $B_{2u}$ or $B_{3u}$ pairing symmetries. Furthermore, we map out the in-gap Majorana surface-bound modes existing on the (0-11) surface, and discuss their potential for additional insight into the pairing structure of ${\mathrm{UTe}}_2$.

We introduce a solvable four-band model to study electron energy levels in disordered transition metal dichalcogenides. Electron states in the pristine monolayer are described by a $\mathit{k}·\mathit{p}$ Hamiltonian. Point defects are assumed to be randomly distributed on a regular lattice. The interaction of electrons with the defects is accounted for by a separable pseudopotential, thus yielding a solvable model suitable for long- and short-range interactions. The coherent potential approximation is used to obtain the configurationally averaged density of states. We compare to models of disorder, namely, binary disorder and Anderson disorder. Importantly, both disorder models yield consistent outcomes, demonstrating that an increase in disorder strength results in a narrowing of the energy gap. Remarkably, CPA with binary disorder provides results that are in very good agreement with available density functional theory and experimental data for the optical gap in the monolayer alloy ${\mathrm{Mo}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$. Moreover, it entails less computational effort than density functional theory calculations.

We experimentally realize the selectively controllable dissipative coupling and coherent coupling induced by different magnon modes and the same antiresonance mode. It has been observed that the weaker the dynamic microwave field generated by the magnon mode in magnetic materials, the more likely dissipative coupling is to occur. Conversely, a stronger dynamic microwave field generated by the magnon mode favors coherent coupling. Based on this principle, we have designed and implemented a system that alternates between dissipative and coherent coupling. It allows microwave signals to be selectively transmitted over a large applied magnetic field range at the frequency of antiresonance. Our experimental achievements may promote the construction of new magnon devices such as a magnetic field-driven microwave switch.

Numerical simulations have shown that skyrmion-like domains with a skyrmion number of 2 can deviate from the analytically predicted single-core form, especially in systems with long-range interactions; therefore, higher-order skyrmion states may also exhibit nontrivial and previously unreported structures. Exploring these configurations may provide new insights into the diversity of topological magnetic textures and the role of competing interactions in stabilizing complex spin structures. This study investigates the magnetic structures of skyrmion-like domains produced in a circular magnetic nanodisk based on the numerical simulations of the Landau-Lifshitz-Gilbert equation, including long-range dipole-dipole interactions. By initializing the domain wall with magnetic moments following different integer-winding patterns, stable magnetic states with high-order skyrmion numbers are obtained. For skyrmion numbers equal to or greater than positive 2, the relaxed states consistently exhibit a multicore structure consisting of a central core and several surrounding outer cores. These configurations resemble interconnected structures comprising multiple skyrmions and antiskyrmion-like domains. By contrast, for negative skyrmion numbers, the domain stabilizes into a simpler configuration with only a single inner core and no outer cores; this configuration closely resembles previously known analytical forms. The contrasting features between the states of the positive and negative skyrmion numbers can be explained by the orientation of the demagnetizing field in the domain generated by the domain wall. These findings indicate that controlling the transitions between these states would facilitate the development of skyrmion-number-based devices with multiple stable magnetic states.

To clarify the relationship between edge electronic states in open-boundary crystalline systems and their corresponding bulk electronic structure, A. Alase et al., [Phys. Rev. Lett. 117, 076804 (2016)] have recently generalized Bloch's theorem to lattice models with broken translational symmetry. Their formalism provides a bulk-boundary correspondence indicator, $D$, sensitive directly to the localization of edge states. We extend this formalism in two significant ways. First, we explicitly classify the edge-state basis provided by the theory according to their underlying protecting symmetries. Second, acknowledging that the true topological invariant is the Zak phase, inherently defined only for periodic boundary conditions, we introduce an analogous quantity ${\gamma }_Z$, suitable for open-boundary systems. We illustrate these developments on the example of the Kitaev wire model. We demonstrate that both indicators, $D$ and our open-boundary analog, ${\gamma }_Z$, effectively capture topological localization: while $D$ diverges within the topological phase, ${\gamma }_Z=\pi$. We further examine eigenvalues ($z$) of the lattice shift operator, showing that variations in these eigenvalues as a function of chemical potential provide additional signatures of topological phase transitions. Additionally, we study a periodic Kitaev wire containing a bond impurity, revealing that while the topological phase remains characterized by ${\gamma }_Z=\pi$, significant state localization near the impurity emerges only at critical values of the chemical potential.

The Dirac fermion with linear dispersion in the kagomé lattice governs the low-energy physics of different valleys at two inequivalent corners of the hexagonal Brillouin zone. The effective Hamiltonian based on the cyclic permutation symmetry of sublattices is constructed to show that the topology of Dirac fermions at these two valleys is characterized by opposite winding numbers. For spinless fermions, the many-particle interactions produce intervalley scattering and drive an intervalley coherent state with spontaneous translation symmetry breaking. The Dirac fermions acquire a mass from the simultaneous charge and bond orderings. In this phase, the developed bond texture underlies a hollow-star-of-David pattern in a tripled Wigner-Seitz cell of the kagomé lattice. It is further demonstrated that the twisting of Dirac mass with vorticity leads to Dirac zero modes at the vortex core, which lead to fractionalization and anyon statistics. The hollow-star-of-David phase is shown to have a distinct ${\mathbb{Z}}_6$ Berry phase with its sign-change counterpart of Dirac mass, i.e., the hexagonal phase, shedding light on the topological origin of Dirac zero modes around the vortex core.

Symmetry, crystal, and electronic structure properties for the second-order Ruddlesden-Popper phase of ${\mathrm{Sr}}_3{\mathrm{Fe}}_2{\mathrm{O}}_7$ are comprehensively analyzed with the help of group-theoretical approaches and hybrid DFT calculations. This study is motivated by recent findings on cooperative Jahn-Teller (JT) distortion in ${\mathrm{Sr}}_2{\mathrm{FeO}}_4$ [G. Zvejnieks et al., Sci. Rep. 13, 16446 (2023)] and the charge order (CO) transition in ${\mathrm{Sr}}_3{\mathrm{Fe}}_2{\mathrm{O}}_7$ [J.-H. Kim et al., Phys. Rev. Lett. 127, 097203 (2021)]. We employed the amplimodes method to identify irreducible representations (irreps) of symmetry modes responsible for phase transitions in ${\mathrm{Sr}}_3{\mathrm{Fe}}_2{\mathrm{O}}_7$. The total electronic energies were calculated using the linear combination of atomic orbitals formalism and were compared for the two distinct orthorhombic symmetries and the tetragonal phase of ${\mathrm{Sr}}_3{\mathrm{Fe}}_2{\mathrm{O}}_7$. The hybrid DFT functionals used in this analysis, PBE0, WC3PW, HSE06, ${\mathrm{r}}^2\mathrm{SCANh}$, and ${\mathrm{r}}^2\mathrm{SCAN}0$, represent the most important types of hybrid DFT functionals. Depending on the choice of hybrid DFT functional, we identify as the ground state either the orthorhombic space group $Cmcm$ (CO-related symmetry mode $\mathrm{X}2-$, No. 63) or SG $Cmce$ (JT-related symmetry mode $\mathrm{X}2+$, No. 64) in the relaxed atomic structures. The interplay between the cooperative effects, such as JT distortion and charge ordering, highlights the importance of selecting the appropriate hybrid DFT functional to capture relevant exchange effects accurately. The ${\mathrm{r}}^2\mathrm{SCANh}$ functional with 10% exact Hartree-Fock (HF) exchange and ${\mathrm{r}}^2\mathrm{SCAN}0$ (with 25% exact HF exchange) yield the SG $Cmcm$ (No.63) ground state in agreement with the recent experimental observations. We thoroughly analyze and compare the crystal structure properties calculated for the chosen hybrid DFT functionals. Furthermore, only test calculations are performed to evaluate the effect of noncollinear magnetic structures. Finally, the electronic density of states for both the orthorhombic and tetragonal structures, calculated with the ${\mathrm{r}}^2\mathrm{SCANh}$ functional, emphasizes the changes induced by the cooperative effects on the electronic properties.