We investigate the structure-dynamics relation of the densely packed, glass-forming ${\mathrm{Ni}}_{66.7}{\mathrm{B}}_{33.3}$ melt using a combination of neutron diffraction and isotopic substitution as well as x-ray diffraction. By additionally utilizing the containerless experimental method of electrostatic levitation, we were able to obtain partial structure factors of high precision. Self- and interdiffusion coefficients were calculated by using the measured partial structure factors as an input for the mode-coupling theory of the glass transition. These are in qualitative agreement with experimentally measured results for liquid ${\mathrm{Ni}}_{66.7}{\mathrm{B}}_{33.3}$. Despite a similar packing density in ${\mathrm{Zr}}_{64}{\mathrm{Ni}}_{36}$, it is found that the calculated diffusivities $D_{\text{Ni}}$ and $D_{\text{B}}$ in ${\mathrm{Ni}}_{66.7}{\mathrm{B}}_{33.3}$ differ from each other by a factor of 2. However, the Darken approximation for the relation of self- and interdiffusion is applicable for the ${\mathrm{Ni}}_{66.7}{\mathrm{B}}_{33.3}$ melt.

${\mathrm{LaCrGe}}_3$ has attracted attention as a potential candidate for studies of quantum phase transitions in a ferromagnetic material. The application of pressure avoids a quantum critical point by developing a new magnetic phase. It was suggested that the disorder may provide an alternative route to a quantum critical point. We used low-temperature 2.5 MeV electron irradiation to induce relatively small amounts of pointlike disorder in single crystals of ${\mathrm{LaCrGe}}_3$. Irradiation leads to an increase of the resistivity at all temperatures with some deviation from the Matthiessen rule. Hall effect measurements show that electron irradiation does not cause any detectable change in the carrier density. Unexpectedly, the Curie temperature, $T_{\text{FM}}$, increases with the increase of disorder from approximately 90 K in pristine samples up to nearly 100 K in the heavily irradiated sample, with a tendency towards saturation at higher doses. This effect is observed both in resistivity and magnetization measurements. Although the mechanism of this effect is not entirely clear, we conclude that it cannot be caused by effective “doping” or “pressure” due to electron irradiation. We suggest that disorder-induced broadening of a sharp peak in the density of states, $D\left(E\right)$, situated at $E_p=E_F-0.25$ eV below the Fermi energy, $E_F$, causes an increase in $D\left(E_F\right)$, leading to an enhancement of $T_{\text{FM}}$ in this itinerant ferromagnet.

The magnetic field–temperature ($H-T$) phase diagram of the multiferroic manganite $\mathrm{YM}{\mathrm{n}}_2{\mathrm{O}}_5$ has been investigated by magnetization and ferroelectric polarization experiments along the three crystallographic directions under the high magnetic field. For $H$//$a$, at 1.6 K, magnetization experiments reveal a significant anomaly in the magnetic field of 28 T, which is associated with a second-order phase transition into a fully polarized state characterized by the nearly saturated polarization ($P$) curve. Intriguingly, an additional first-order transition is observed at 10 T and 18 K and then gradually moves towards higher magnetic fields, and finally merges with the above transition with increasing temperatures. As a result, the two magnetic transitions lead to an exotic ν-like $P$($H$) curve, indicating the strong magnetoelectric coupling in $\mathrm{YM}{\mathrm{n}}_2{\mathrm{O}}_5$. In particular, a field-induced $P$ flip is realized at low temperatures, which may be attributed to the inversion of the vector spin chirality. Furthermore, this feature with distinct origins is also observed for other orientations of the magnetic field. In the $H$//$b$ geometry, a first-order spin-flop transition occurs below 18 K, compatible with the $P$ reversal. However, no anomaly in magnetizations is found in the case of $H$//$c$. Note that the magnetization of $\mathrm{YM}{\mathrm{n}}_2{\mathrm{O}}_5$ is far below its saturation value even up to 55 T. These studies could contribute to an in-depth understanding of the underlying physics in this family of compounds.

There are two different pairing potentials for the superconductivity of doped Weyl semimetals, i.e., the internode BCS pairing and the intranode Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing. We show that the superconducting pairing potentials can be clearly distinguished from the frequency characteristics of optical conductivity. The pairing-dependent optical conductivities for the BCS and FFLO pairings are calculated. The optical conductivities exhibit two types of distinct resonances, the Van Hove resonance for the BCS pairing and the resonance with a threshold for FFLO pairing. The result provides a method of identifying the pairing potential in superconducting Weyl semimetals.

We study the commensuration torques and layer sliding energetics of twisted trilayer graphene (t3G) and twisted bilayer graphene on hexagonal boron nitride (t2G/BN) that have two contiguous superposed moiré interfaces. Lattice relaxations for typical graphene twist angles of $\sim 1^{\circ }$ in t3G or t2G/BN are found to break the out-of-plane layer mirror symmetry, give rise to layer rotation energy local minima dips of the order of $\sim {10}^{-1}$ meV/atom at double moiré alignment angles, and have stacking energy minima of comparable magnitude between the next-nearest top-bottom layers. Thus, in t3G, the top and bottom layers tend to align when one twisted interface angle is fixed, whereas in t2G/BN, the alignment of the two moiré patterns favors t2G with $\theta \simeq 1.{12}^{\circ }$ near the magic angle when the G/BN interface is rotated at $\theta \simeq 0.{56}^{\circ }$. Precedence of rotation over sliding during the moiré commensuration is confirmed for periodic boundary systems where the sliding energy barriers drop to $\sim {10}^{-4}$ meV/atom for physical misalignment angles as small as $\sim 0.{03}^{\circ }$. For finite graphene flakes of diameter $D,$ we find enhanced friction forces for a wider range of angles $\mathrm{\Delta }{\theta }_{\mathrm{FWHM}}\sim C/D$ both near the zero alignment angle in t2G and commensurate double moiré angles in t3G.

Hyper-Raman scattering is used to study the temperature dependence of the longitudinal optic (LO) modes of three prototypical ferroelectric relaxors in a broad temperature range from 20 to 800 K. The three LO bands observed in all spectra of the three materials are linked to the three transverse optic (TO) modes in cubic relaxors where ${\mathrm{LO}}_i$ is linked to ${\mathrm{TO}}_i$, with $i$ = 1 to 3. The Last, Slater, and Axe eigenvector pictures of the TO modes are consistent with our observations on LO1, LO2, and LO3, respectively. Within this framework, the splitting of LO2 would mostly be linked to a structural disorder on the B site while the strength of an anomaly of LO1 near the freezing temperature $T_f$ relies on the ability of the material to develop a long-range ordering. Moreover, the more pronounced the splitting, the more important the structural disorder and the lower the value of the dielectric constant.

Multiple anomalous features in electronic spectra of metals with a kagome lattice structure—van Hove singularities, Dirac points, and flat bands—imply that materials containing this structural motif may lie at a nexus of topological and correlated electron physics. Due to the prospects of such exceptional electronic behavior, the recent discovery of superconductivity coexisting with charge-density wave (CDW) order in the layered kagome metals $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A$ = K,Rb,Cs) has attracted considerable attention. Notably, these archetypal kagome metals express unconventional magnetotransport behavior, including an unexpected linear-in-$H$ diagonal resistivity at low fields, and an even more peculiar, nonmonotonic sign-changing behavior of the Hall resistivity, which has been speculated to arise from a chiral CDW. We argue here that this unusual magnetotransport derives not from such unconventional phenomena, but rather from the unique fermiology of the $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ materials. Specifically, it is caused by a large, concave hexagonal Fermi surface sheet formed in the close proximity to the van Hove singularities, which is backfolded into a small hexagonal sheet and two large triangular sheets in the CDW state. We introduce and analyze a model of the electronic structure of these Fermi surface sheets that allows for a full analytical treatment within Boltzmann kinetic theory and that enables semi-quantitative fits of our transport data. Specifically, we find that the anomalous magnetotransport behavior is caused by the confluence of strong reduction of the Fermi velocity near the van Hove singularities located near the vertices of the hexagonal sheet and sharp corners in Fermi surface generated by the CDW reconstruction. Our analytical approach not only explains the anomalous magnetotransport in the kagome superconductors but also can be extended to a variety of metallic systems hosting singular features in their Fermi surfaces.

In a series of recent papers starting with Phys. Rev. B 103, 094501 (2021), Liu, Yang, Pan et al. claim to have determined the exact dressed electron-boson vertex for a number of very general interacting many-body problems by inverting certain Ward-Takahashi identities. Here, we point out that their Ward-Takahashi identities are missing terms which make the inversion of the identities impossible. One therefore cannot formulate exact self-contained integral equations for the dressed electron propagator. In addition, the proposed vertex expressions do not reproduce well-established results for the leading perturbative corrections.

In a series of papers, we have proposed a nonperturbative field-theoretic approach to deal with strong electron-phonon and strong Coulomb interactions. The key ingredient of such an approach is to determine the full fermion-boson vertex corrections by solving a number of self-consistent Ward-Takahashi identities. Palle argued that our Ward-Takahashi identities failed to include some important additional terms and thus are incorrect. We agree that our Ward-Takahashi identities have ignored some potentially important contributions and here give some remarks on the role played by the additional terms.

Half-metal ferromagnets were predicted [Cahaya, Tretiakov, and Bauer, IEEE Trans. Magn. 51, 1 (2015)] to give large thermoelectric performance in antiparallel spin valve configuration. Despite being metals that suffer from the Wiedemann-Franz law, the additional spin degrees of freedom allow for tuning of the thermoelectric properties due to the spin valve enhancement factor. We test this theory and find a mismatch of parameters that gives large thermoelectric performance and large spin valve enhancement factor. As a result, we show that the spin valve setup is useful only for half-metal ferromagnets with initially poor thermoelectric performance. To obtain the largest thermoelectric performance, one still needs to open the band gap.

In this work we propose that Majorana zero modes can be realized at the corners of the two-dimensional unconventional insulator. We demonstrate that $1T\text{−}{\mathrm{PtSe}}_2$ is a symmetry indicator-free (SI-free) unconventional insulator originating from orbital hybridization between Pt $d$ and Se $p_{x,y}$ states. The kind of SI-free unconventionality has no symmetry eigenvalue indication. Instead, it is diagnosed directly by the Wannier charge centers by using the one-dimensional Wilson loop method. The obstructed edge states exhibit strong anisotropy and large Rashba splitting. By introducing superconducting proximity and an external magnetic field, the Majorana corner modes can be obtained in the $1T\text{−}{\mathrm{PtSe}}_2$ monolayer. In the end, we construct a two–Bernevig-Hughes-Zhang model with anisotropy to capture the Majorana physics.

The charge-2 (C2) triple point (TP) is a zero-dimensional threefold band degeneracy with a topological charge $\left|C\right|=2$. Different from other types of TP, the C2 TP is expected to have novel physical properties because of its nonzero topological charge. However, the C2 TP is only found in nonmagnetic materials and has not been found in realistic magnetic materials. In this work, we systematically study such fermions in nonmagnetic and ferromagnetic systems. Based on 230 space groups (SGs), we confirm that 13 SGs could host the C2 TP at high-symmetry points. By first-principles calculations and high-throughput material screening, we identify 82 candidate materials, which host a nonmagnetic or ferromagnetic C2 TP. The lattice parameters, magnetic ground states, spin-polarization ratio, and positions of the C2 TP in momentum/energy space of these candidate materials are also given in detail. To support our theory, we take BaPPt and ${\mathrm{MnBi}}_{12}{\mathrm{O}}_{20}$ as examples for detailed analysis, which host spinless and full spin-polarized C2 TPs. In particular, a long Fermi arc extended in the whole Brillouin zone is clearly observed. Our work paves the way to study the C2 TP and provides candidate materials for future study of physical properties, experimental research, and device application.

Current-induced out of plane magnetization has been utilized for field-free switching of ferromagnets with perpendicular magnetic anisotropy. Identifying systems capable of energy-efficiently converting charge currents into out of plane orbit- or spin-polarized currents is crucial for advancing magnetic memory technologies. Here we introduce the Berry curvature dipole as a key evaluation factor, directly measurable through nonlinear Hall effects. In the Weyl semimetal $\mathrm{TaIrT}{\mathrm{e}}_4$ used in our experiments, applying a current parallel to the Berry curvature dipole results in out of plane orbital magnetization, which governs the field-free perpendicular magnetization switching in $\mathrm{TaIrT}{\mathrm{e}}_4$/$\mathrm{F}{\mathrm{e}}_3\mathrm{GaT}{\mathrm{e}}_2$ heterostructures. Notably, all-electric control of van der Waals magnetoresistive memory at room temperature has been achieved with a low critical current density $\sim 2\times {10}^6\mathrm{A}/\mathrm{c}{\mathrm{m}}^2$ for data writing. Our findings reveal the connection between nonlinear Hall effects and field-free magnetization switching, highlighting the potential of the Berry curvature dipole in advancing orbitronics.

Kibble-Zurek mechanism relates the domain of nonequilibrium dynamics with the critical properties at equilibrium. It establishes a power law connection between nonequilibrium defects quenched through a continuous phase transition and the quench rate via the scaling exponent. We present a novel numerical scheme to estimate the scaling exponent wherein the notion of defects is mapped to errors, previously introduced to quantify a variety of gapped quantum phases. To demonstrate the versatility of our method we conduct numerical experiments across a broad spectrum of spin-half models hosting local and symmetry protected topological order. Furthermore, an implementation of the quench dynamics featuring a topological phase transition on a digital quantum computer is proposed to quantify the associated criticality.

In quantum dot junctions capacitively coupled to a resonator, electron tunneling through the quantum dot can be used to transfer heat between different parts of the system. This includes cooling or heating the electrons in electrodes and absorbing or emitting photons in the resonator mode. Such systems can be driven into a nonequilibrium state by applying either a voltage bias or a temperature gradient across the electrodes coupled to the quantum dot, or by employing an external coherent pump to excite the resonator. In this paper, we present a semiclassical theory to describe the steady state of these structures. We employ a combination of the Floquet–nonequilibrium Green's function method and semiclassical laser theory to analyze a normal metal–quantum dot–superconductor junction coupled to a resonator. Our paper focuses on key parameters such as the average photon number and phase shift in the resonator, the charge current in the quantum dot, and the heat fluxes among different components of the system. We explore how photon-assisted Andreev reflection and quasiparticle tunneling in the quantum dot can refrigerate the resonator mode and the normal-metal electrode. We also examine the influence of finite voltage and thermal biases on these processes.

This study aims to investigate the interplay between chiral-induced spin-orbit coupling along the screw axis and antisymmetric spin-orbit coupling (ASOC) in the normal plane within a chiral crystal, using both general model analysis and first-principles simulations of InSeI, a chiral van der Waals crystal. While chiral molecules of light atoms typically exhibit spin selectivity only along the screw axis, chiral crystals with heavier atoms can have strong ASOC effects that influence spin-momentum locking in all directions. The resulting phase diagram of spin accumulation shows the potential for controlling phase transition and flipping spin by reducing symmetry through surface cleavage, thickness reduction or strain. We also experimentally synthesized high-quality InSeI crystals to demonstrate the feasibility and thermal stability of the proposed material. This lays a solid foundation for the realization of transverse spin selectivity in chiral crystals, facilitating the development of spintronic devices.

Thermalization time marks the scale at which the subsystem entanglement reaches its thermal value. It was recently shown to exhibit two distinct stages in a generic class of quantum circuits with decay rates $r_1$ and $r_2$ before and after thermalization. The two rates are observed in the Floquet dynamics of the state purity, entanglement spectra, and (local) correlation functions, both in clean and disordered systems. Entanglement membrane theory interprets $r_1$ as domain-wall energy and $r_2$ as either a geometric effect (phantom eigenvalue) or a competition with an emergent magnon mode. In the case when the domain wall dominates, this offers a practical measure for entanglement growth via local correlations.

Nonlinear electrical conduction primarily mediated by an orbital texture is observed in chiral semiconductor Te. We determine the enantiospecific sign of the nonlinear conductance and identify anomalies in its carrier-density dependence. Our findings, combined with the Boltzmann equation, are attributed to a chiral orbital texture, namely a chiral distribution of the orbital magnetic moment in reciprocal space. This study underscores the efficacy of nonlinear transport measurements in probing orbital-related effects, whose differentiation from spin counterparts is often demanding in the linear response regime of electron transport.

Due to the coupled spin-valley physics, monolayer 2D transition metal dichalcogenides (TMDs) show many unusual electronic and transport properties. Here, we show that a magnetic impurity in the metallic TMDs such as the $2\mathrm{H}\text{−}{\mathrm{NbSe}}_2$ induces a large orbital polarization in its neighborhood with a Friedel type oscillation, in addition to the usual spin polarization. We study the orbital polarization, hitherto unexplored for any impurity system, using the impurity Green's function approach as well as tight-binding and density functional methods. Concrete results are presented for the Mn substitutional impurity in ${\mathrm{NbSe}}_2$ from density-functional calculations. The orbital polarization here is due to the orbital moment imbalance between the $K/K^{\prime }$ valleys, which is driven by the impurity-induced spin imbalance. Our work demonstrates the Friedel oscillation for the first time in the orbital channel. Our results should be readily accessible for experimental study using techniques such as the spin polarized scanning tunneling microscopy.