Topological characteristics of quantum systems are typically determined by the closing of a gap, while the dynamical quantum phase transition (DQPT) during quantum real-time evolution has emerged as a nonequilibrium analog to the quantum phase transition (QPT). In this paper, we illustrate that the system dynamics can be elucidated by considering the precession of a collection of free pseudospins under a magnetic field based on the exact results of extended Kitaev chains. The topology of the driven Hamiltonian is determined by the average winding number of the nonequilibrium state. Furthermore, we establish that the singularity of the DQPT arises from two perpendicular pseudospin vectors associated with the pre- and postquenched Hamiltonians. Moreover, we investigate the distinct behaviors of the dynamic pairing order parameter in both topological and nontopological regions. These findings offer valuable insights into the non-equilibrium behavior of topological superconductors, contributing to the understanding of the resilience of topological properties in driven quantum systems.

We explore the electronic and structural properties of $Fm\overline{3}m$ Lu-H-N structures with specific N,H ordering due to their remarkably narrow hydrogen-based bands at the Fermi level. Although ${\mathrm{LuH}}_{2.875}{\mathrm{N}}_{0.125}$ exhibits a classical instability persisting up to 17 GPa, it is anharmonically stable near ambient pressure when accounting for quantum nuclear effects. The presence of flat bands near $E_{\text{F}}$ is understood to arise from destructive quantum interference between ${\mathrm{N}}_{\mathrm{p}}$ and surrounding ${\mathrm{H}}_{\mathrm{s}}$ orbitals, with certain types of defects leaving the flat bands unaffected. The results suggest that if this system is superconducting, there is an optimal pressure near ambient where the superconducting $T_{\text{c}}$ is maximized by anharmonically stabilized low-frequency and nonadiabatically coupled high-frequency hydrogen modes. Despite the metastability of this structure, its dynamical stability when modeled beyond a classical harmonic approach suggests the narrow bands near $E_{\text{F}}$ do not cause structural distortions in certain Lu-H-N stoichiometries.

We study the diffusive dynamics of the classical one-dimensional lattice model of mobile particles featuring the incoherent metallic state of the organic TTF-CA found in the vicinity of the neutral-ionic(NI) transition. The particles are strongly correlated and feel the alternating site potentials, exhibiting uniform ionic (I) Mott insulating and neutral band insulating (N) phases when the Coulomb interaction and site potentials are large, respectively. We focus on the neutral-ionic domain walls (NIDW) activated by their competition, which are typically regarded as fractionalized particles. The finite temperature phase diagram reveals a thermodynamically stable NIDW phase not found in previous literature that emerges at the triple point, where the transition line splits into two first-order lines toward the critical endpoints. We analyze the long-time behavior of dynamics of the NIDWs and find that it captures the diffusive transport of the system. The conductivity derived from the diffusion constant and the number population of NIDWs shows a strong enhancement inside the NIDW phase, which can explain the large conductivity at the NI crossover found in TTF-CA.

We study the effects of integrability breaking on the relaxation dynamics of the (double) sine-Gordon model. Compared to previous studies, we apply an alternative viewpoint motivated by open-system physics by separating the phase field into homogeneous and inhomogeneous parts, describing a quantum pendulum (subsystem) and an interacting phononic bath (environment). To study the relaxation dynamics in the model, we perform quantum quenches using the mini-superspace-based truncated Hamiltonian approach developed recently and simulate the real-time evolution of various entanglement measures and the energy transfer between the subsystem and its environment. Our findings demonstrate that in the presence of integrability-breaking perturbations, the relaxation dynamics is substantially faster, signaled by the increase of entanglement and energy transfer between the quantum pendulum and the phonon bath.

In this paper we propose two theoretical models of a metallic Néel ordered antiferromagnet with charge-density wave order which shows the anomalous Hall effect. In our models a combination of the Néel order and the charge-density wave order results in spin splitting of the conducting fermions. In addition, spin-orbit coupling is required to drive the anomalous Hall effect. In the first model we analyzed the effects of the Rashba spin-orbit coupling, and of the intrinsic $d\text{−}\text{wave}$ spin-orbit coupling in the second model.

In this work, we investigate the reflection properties on the interface between an ordinary dielectric medium and a dielectric supporting a magnetic current (equivalent to a dielectric governed by axion electrodynamics). Considering the usual Maxwell equations and constitutive relations, we derive the general Fresnel coefficients for reflection for an incident wave with $s$ and $p$ polarization, assuming an isotropic magnetic current on a dielectric substrate. We determine all total internal reflection and critical angles (Brewster angles) conditions, which are given by strict relations between all relevant electromagnetic quantities of the system and the frequency. For $s$- and $p$-polarized incident waves, total internal reflection can occur under certain conditions on the constitutive parameters (for each propagating mode) at specific frequency windows and certain incidence angle intervals. All possible conditions to define critical angles for null reflection are determined. This scenario allows polarization changes by reflection. Considering a $p$-polarized incident wave, the frequency and the Brewster angle, allowing null reflection for both propagating modes, are determined. The Goos-Hänchen shift and the complex Kerr rotation are also evaluated. The Kerr ellipticity angle presents a frequency-dependent behavior, also reported in Weyl semimetals, having maximum values ${\eta }_{\mathrm{Kerr}}=\pm \pi /4$ for specific values of frequency, which may work as a signature of this axion chiral dielectric.

The impact of the local chemical environment on the Gilbert damping in the binary alloy ${\mathrm{Fe}}_{100-x}{\mathrm{Co}}_x$ is investigated, using computations based on density functional theory. By varying the alloy composition $x$ as well as Fe-Co atom positions we reveal that the effective damping of the alloy is highly sensitive to the nearest-neighbor environment, especially to the amount of Co and the average distance between Co-Co atoms at nearest-neighbor sites. Both lead to a significant local increase (up to an order of magnitude) of the effective Gilbert damping, originating mainly from variations of the density of states at the Fermi energy. In a global perspective (i.e., making a configuration average for a real material), those differences in damping are masked by statistical averages. When low-temperature explicit atomistic dynamics simulations are performed, the impact of short-range disorder on local dynamics is observed to also alter the overall relaxation rate. Our results illustrate the possibility of local chemical engineering of the Gilbert damping, which may stimulate the study of new ways to tune and control materials aiming for spintronics applications.

To achieve room-temperature high spin polarization and pursue potential applications in high-performance spintronic device, the study of two-dimensional (2D) half-metallic materials is of great interest. Here, by employing first-principles calculations, we have predicted a stable 2D monolayer ferromagnetic half-metal ${\mathrm{Mn}}_2{\mathrm{Se}}_2\mathrm{O}$, exhibiting a high Curie temperature of nearly 467 K, a sizable in-plane magnetic anisotropy ($306\mu \mathrm{eV}/\mathrm{Mn}$), and a wide spin gap of 2.0 eV. Notably, an exotic magnetic phase transition from ferromagnetism to altermagnetism is predicted by applying a moderate compressive strain, while the half-metallic ferromagnetic ordering of the ${\mathrm{Mn}}_2{\mathrm{Se}}_2\mathrm{O}$ monolayer is robustly retained under tensile strains. Furthermore, the half-metallicity of the ${\mathrm{Mn}}_2{\mathrm{Se}}_2\mathrm{O}$ monolayer makes it an ideal electrode candidate that is used in the magnetic tunnel junction with a colossal tunnel magnetoresistance ratio of about ${10}^{12}\%$. Our findings not only expand the comprehensive understanding of a 2D room-temperature ferromagnet with promising spintronics electrode application, but they also offer a potential avenue for designing magnetomechanical coupling spintronic devices.

In this paper, we establish the upper critical field-temperature (${\mu }_0{H}_{\mathrm{c}2}\text{−}T$) phase diagram of $2H\text{−}{\mathrm{Pd}}_{0.04}\mathrm{Ta}{\mathrm{S}}_2$ single crystal ($T_{\mathrm{c}}=4.5\mathrm{K}$) by magnetotransport measurements with temperatures down to 0.31 K at static magnetic fields up to 45.22 T. The in-plane and out-of-plane upper critical fields are estimated as ${\mu }_0{H}_{\mathrm{c}2}^{//ab}\left(0\right)\approx 40\mathrm{T}$ and ${\mu }_0{H}_{\mathrm{c}2}^{\perp ab}\left(0\right)\approx 4.5\mathrm{T}$, respectively. The angle dependence of upper critical field ${\mu }_0{H}_{\mathrm{c}2}$(θ) at $T$ = 3.5 K in the vicinity of θ = 90° displays a bell shape rather than a cusp, suggesting a three-dimensional superconductivity in this system. A change from three to two dimensionality is characterized by the curvature evolution of ${\mu }_0{H}_{\mathrm{c}2}$($T$) and the out-of-plane coherence length ${\xi }_c$($T$) comparable with the interlayer spacing. The dimensional crossover indicates the weakening of the interlayer coupling by Pd intercalation, which results in the enhanced spin-orbital coupling (SOC). The extremely large ${\mu }_0{H}_{\mathrm{c}2}^{//ab}$ far beyond the BCS weak-coupling Pauli limit is mainly attributed to spin-momentum locking induced by the enhancement in SOC.

We theoretically demonstrate a spontaneous spin superconductor (SC) state in ABCA-stacked tetralayer graphene, under sequential effects of electron-electron (e-e) and electron-hole (e-h) interactions. First of all, we examine the ferromagnetic (FM) exchange instability and phase diagram of the system induced by the e-e Coulomb interaction. At non- or low-doping levels, the interaction trends to stabilize an FM phase with the coexisting electron and hole carriers. Superior to bilayer and trilayer systems, tetralayer graphene has a larger FM phase region and spin splitting, making it more advantageous to realize the spin SC state. Subsequently, we prove that the FM state becomes unstable when attractive e-h interaction is considered at low temperature. As a consequence, the spin SC state can be spontaneously formed, where spin-triplet exciton pairs act as the equivalent of Cooper pairs. We further develop a consistent BCS-type theory for the spin SC state in ABCA-stacked graphene. The predicted spin superconducting gap can reach about $7.0\mathrm{meV}$, with a critical temperature of about 45 K for a nondoping system. At last, we demonstrated a spin-current Josephson effect in the ABCA-stacked graphene spin SC heterojunction. Our findings enrich the prospective spin SC candidate materials, illuminating more possibilities for achieving nondissipative superspintronics.

Extensive molecular dynamics simulations are performed to investigate the effects of planar shock compression and subsequent release phenomena in preheated single-crystal Ta. Hugoniot structures along three crystallographic orientations are examined with systematic increase in sample temperature towards melting conditions. Study reveals a shift in the onset of plasticity to lower impact velocities and narrowing of elastic-plastic two-wave zone in preheated samples. Building upon our previous approach, we have coupled the spatial decay and strain rate rise of longitudinal stress associated with elastic waves along the (110) and (111) directions. This enabled us to predict Hugoniot elastic limit (HEL) of orders of magnitude larger thickness samples with reasonable level of accuracy. Importance of our study lies in unifying available HEL data spanned over a wide range of sample dimensions and strain rates, including our own, in a universal scaling relation. The anisotropic elastic-plastic response observed in preheated Ta, as evidenced by the temperature dependence of HEL, is comprehended through microstructural analysis focusing on twinning and dislocation-induced plastic deformation. Signature of plastic anisotropy is also reflected in the distinct temperature variation of dislocation density observed for (110) and (111) orientations. Further, influence of elevated sample temperature on shock release phenomena is examined leading to estimation of spall strength. Study for representative impact strengths reveals strong orientation dependence in tensile strength profile for preheated Ta along all three principal directions. For better insights into the compressive and tensile strength at ultrahigh strain rates, we propose a unique analytical function that explains the orientation-dependent temperature variations observed in both HEL and spall strength. A comprehensive understanding of spalling is achieved through in-depth analysis of void nucleation-growth-coalesce dynamics supported by void statistics.

This study investigated the frictional behavior in a single-asperity silicon/graphite junction using an ultrahigh-vacuum atomic friction microscope. While the friction depends weakly on the normal load and logarithmically on the sliding velocity, it exhibits an unconventional temperature dependence, with its magnitude being enhanced at higher temperatures. This counterintuitive behavior challenges the thermally activated mechanism proposed by the Prandtl-Tomlinson model. Our analysis attributes this unconventional frictional behavior on temperature to the dynamic formation and rupture of multiple types of interfacial bonds. These insights can be well captured by our recently developed multicontact model. Our approach and results provide insights in the field of single-asperity nanotribology.

We report a systematic study of the Anderson localization of a three-dimensional (3D) pseudospin-1 system. From an analysis on the symmetry of the Hamiltonian, it can be inferred that the pseudospin-1 system belongs to the class of unitary symmetry according to Wigner's surmise. Such a result of Anderson localization is similar to the case of a pseudospin-$\frac{1}{2}$ system which corresponds to the Weyl or Dirac topological semimetals. By carrying out the numerical calculations, we find that the statistical distributions of the adjacent energy level difference conform to the unitary distribution very well for both the pseudospin-1 and pseudospin-$\frac{1}{2}$ systems. Furthermore, by taking a scaling analysis of the numerical result of the localization length, we obtain the critical exponent of the Anderson transition, $\nu =1.42\pm 0.04$, for pseudospin-1 system, very close to the standard value of the unitary class systems ($\nu =1.443\pm 0.003$). All these numerical results confirm unambiguously that the 3D pseudospin-1 system falls within the class of unitary symmetry, just like the pseudospin-$\frac{1}{2}$ system. Furthermore, the numerical results demonstrate that the pseudospin-1 system exhibits Anderson localization at a lower critical disorder strength than the pseudospin-$\frac{1}{2}$ system. We then generalize Ziman's approach to explain this phenomenon. Our findings indicate that the underlying physical reason for the result that the pseudospin-1 system can enter the localization regime at a smaller disorder strength than the pseudospin-$\frac{1}{2}$ system can be ascribed to the smaller average coordinate number.

Electronic structure analysis is performed to study the properties of several Pb-containing $3d$ intermetallics. Our study reveals that binary metastable $\mathrm{C}{\mathrm{o}}_3\mathrm{Pb}$ and $\mathrm{F}{\mathrm{e}}_3\mathrm{Pb}$ intermetallic compounds exhibit very attractive intrinsic magnetic properties. We primarily focus on the magnetic anisotropic properties arising from the high spin-orbit coupling of the Pb atom. Decomposing the total anisotropy into intra- and interatomic contributions reveals a significant deviation from single-ion anisotropy model with strong symmetric anisotropic pair interactions present. Furthermore, we consider magnetic properties of ternary Pb-based $3d$ intermetallics, which recently have been reported as stable or metastable. Giant magnetic anisotropy is found on Pb atoms in these systems. The origin of such strong anisotropy in $\mathrm{L}{\mathrm{a}}_{18}\mathrm{C}{\mathrm{o}}_{28}\mathrm{P}{\mathrm{b}}_3$ appears from two sources: spin-orbit and interelectronic Breit couplings. The significance of Breit interaction for magnetic anisotropy in bulk systems is reported. It is expected that Breit coupling-induced anisotropy is dominating in magnetic Pb-based magnets with lower dimensionality including thin films.

The influence of the Co- and W-layer stacking sequence and the Co-layer thickness $d_{\mathrm{Co}}$ on the magnetization precession and damping and magnetic anisotropy is investigated using the all-optical time-resolved magneto-optical Kerr (TRMOKE) effect in asymmetric Pt/W/Co/Pt and Pt/Co/W/Pt heterostructures prepared by molecular beam epitaxy. It is found that the reversing of the stacking sequence of the Co and W layers leads to significant changes in the magnetic-field $H$ dependencies of the magnetization precession frequency $f$ and the effective damping parameter ${\alpha }_{\mathrm{eff}}$ for different $d_{\mathrm{Co}}$ thicknesses. A quantitative analysis of the $f\left(H\right)$ dependencies is carried out within the macrospin precession model, and the effective magnetic anisotropy constants $K_{\mathrm{eff}}$ are determined. It is shown that, in addition to the first-order coefficient $K_1$, also the second-order $K_2$ uniaxial anisotropy constant must be taken into account for the Pt/Co/W/Pt stack, while $K_2$ is insignificant for the reversed Pt/W/Co/Pt stack. From the $K_{\mathrm{eff}}\left(d_{\mathrm{Co}}\right)$ dependencies, the interface $K_{\mathrm{s}}$ and volume $K_{\mathrm{v}}$ anisotropy contributions for all heterostructures are obtained. The value of $K_{\mathrm{s}}=1.24\mathrm{mJ}/{\mathrm{m}}^2$ for the Pt/Co/W/Pt stack is found to be over two times larger as compared to $K_{\mathrm{s}}=0.55\mathrm{mJ}/{\mathrm{m}}^2$ for the Pt/W/Co/Pt one. The interfacial anisotropy induced at the bottom Pt/Co interface in the Pt/Co/W/Pt heterostructure is shown to be significantly larger than that induced at the top Co/Pt interface in the Pt/W/Co/Pt stack. From the effective damping parameter ${\alpha }_{\mathrm{eff}}\left(H\right)$ dependencies, the intrinsic damping ${\alpha }_0$ is extracted, and the interface-induced damping contributions to ${\alpha }_0$ within the spin-pumping model are derived. It is found that the effective spin-mixing conductance parameter $g_{\mathrm{eff}}^{\uparrow \downarrow }$ for the Pt/Co/W/Pt structure exceeds $100{\mathrm{nm}}^{-2}$ and is about two times larger than for the Pt/W/Co/Pt one, indicating the dominant Pt/Co-bottom interface contribution to the spin-pumping damping. A correlation between the intrinsic damping ${\alpha }_0$ and anisotropy constant $K_1$ for all layered structures studied is found and discussed in terms of the dependence of both quantities on the spin-orbit coupling. It is shown that the magnetic anisotropy parameters determined from the dynamic TRMOKE method agree well with those obtained from complementary measurements performed using the static magneto-optical Kerr effect.

Kubo's linear response formalism has been used to calculate the orbital Hall conductivity (OHC) for nonmagnetic undoped and doped transition metal systems, focusing on the impact of different types of disorder and the role of vertex corrections for the OHC. The doping and temperature dependence of the OH conductivity have been investigated and compared with corresponding results for the spin Hall conductivity (SHC). A strong difference has been found between the results for undoped and doped metallic systems. For elemental systems at finite temperature, a dominating role of the intrinsic contribution to the temperature-dependent OH and SH conductivities is found. Moreover, the different temperature-dependent behavior of the intrinsic SOC-independent OHC and SOC-driven SHC indicates a nontrivial relationship between these quantities. It is shown that, in contrast to the intrinsic part of the OH and SH conductivities, the extrinsic contributions in doped systems are determined by spin-orbit coupling for both of them. This effect is dominating at low temperature, strongly decreasing at higher temperatures owing to the increasing impact of the electron-phonon scattering.

An analytical expression of the magnetic susceptibility of materials is derived by means of magnetic Bloch states. The analytical expression consists of two terms. It is shown that the first term of the magnetic susceptibility can not only revisit the de Haas–van Alphen (dHvA) oscillation but also describe additional oscillation peaks. The period of the dHvA oscillation is shown to be associated with the potential energy of the magnetic dipole moment caused by the magnetic Bloch state on the Fermi energy, while in the conventional theory, the period is related to the extreme cross-sectional area of the Fermi surface at zero magnetic field. The second term of the magnetic susceptibility is analogous to the formula of the van Vleck paramagnetism and yields a paramagnetism. The present expression of the magnetic susceptibility is applied to crystalline silicon to describe the magnetic field–induced second-order phase transition from a band insulator to metal which has recently been theoretically predicted. The magnetic oscillation in the metallic phase is caused by magnetic Bloch bands passing through the Fermi energy, which is explained by the first term. The almost constant magnetic susceptibility in the band insulator phase is well described by the second term. Furthermore, we present a sum rule for magnetic dipole moments of magnetic Bloch states.

The quantum dynamics of the intrinsic metric profoundly influence the neutral excitations in the fractional quantum Hall system, as established by Haldane [Phys. Rev. Lett. 107, 116801 (2011)], and further evidenced by a recent two-photon experiment [J. Liang et al., Nature (London) 628, 78 (2024)]. Despite these advancements, a comprehensive understanding of the dynamic properties of these excitations, especially at long wavelengths, continues to elude interest. In this study, we employ tensor-network methods to investigate the neutral excitations of the Laughlin and Moore-Read states on an infinite cylinder. This investigation deepens our understanding of the excitation spectrum in regions where traditional methods do not work effectively. The spectral functions for both states reveal the presence of $S=-2$ geometric excitations. We unveil the complex spectra of both neutral fermion and bosonic Girvin-MacDonald-Platzman modes within the excitation continuum by calculating the three-particle density response function for the Moore-Read state. Our findings support the hypothesis of emergent supersymmetry and highlight the potential for detecting neutral fermions in future experiments.