Interfacial charge transfer kinetics between solid electrolyte (SE) and Li metal in all-solid-state Li-ion batteries is one of the limiting factors for their practical use. The mechanism of interfacial charge transfer is still poorly understood. In this work, we study the Li-ion charge transfer at interfaces between perspective SE of garnet-type ${\mathrm{Li}}_7{\mathrm{La}}_3{\mathrm{Zr}}_2{\mathrm{O}}_{12}$ (LLZO) and Li metal, utilizing the density functional theory and nudged elastic band method (DFT-NEB). We demonstrate that it is crucial to consider the relatively long percolating conduction pathway through the interface. Due to the formation of energy minima for Li vacancies, the activation energies for ${\mathrm{Li}}^{+}$ charge transfer additionally increase by 0.1–0.3 eV compared with ${\mathrm{Li}}^{+}$ migration barriers in bulk LLZO. We show that the formation of interfacial energy minima is because of the electronic density redistribution from the metallic Li to the LLZO region. These results improve our understanding of interfacial charge transfer in solid-state batteries with metallic lithium.

We theoretically investigate high-order harmonic generation (HHG) in graphene under mid-infrared (MIR) and terahertz (THz) fields based on a quantum master equation. Numerical simulations show that MIR-induced HHG in graphene can be enhanced by a factor of 10 for fifth harmonic and a factor of 25 for seventh harmonic under a THz field with a peak strength of 0.5 MV/cm by optimizing the relative angle between the MIR and THz fields. To identify the origin of this enhancement, we compare the fully dynamical calculations with a simple thermodynamic model and a nonequilibrium population model. The analysis shows that the enhancement of the high-order harmonics mainly results from a coherent coupling between MIR- and THz-induced transitions that goes beyond a simple THz-induced population contribution.

Interlayer excitons (IXs) have become an ideal platform for studying exciton condensation, single-photon emission, and other quantum phenomena. Two-dimensional transition metal dichalcogenide (TMD) heterostructures, with type-II band alignment features, provide a simple framework for the formation of IXs. The intrinsic electric field of Janus TMDs can be introduced to tune the type-II band energies. In this paper, we perform GW-BSE calculations to explore how the Janus layers affect the interlayer excitations in WSSe/$\mathrm{W}{\mathrm{S}}_2$-based heterostructures by tuning the spin states. Our results reveal that the parallel-arranged intrinsic electric field structure with the S/Se interface mixes more spin-singlet state into the spin-triplet states, and hence, the lowest IX has a shorter radiative lifetime than other Janus WSSe@$\mathrm{W}{\mathrm{S}}_2$ heterostructures. We also find the S/Se interface makes the energy band more staggered and thus has no bound bright IXs. For S/S interface heterostructures in which the electric field points away from the interface, the strong band hybridization mixes 49% spin-singlet into the spin-triplet states, and therefore, the radiative lifetime of the lowest-energy bright IX is as short as ${10}^{-13}$ s at 0 K. Our explorations show that strong spin-orbit coupling plays a key role in the spin-singlet-triplet mixture in Janus WSSe structures by arranging the direction of the intrinsic electric field.

We present a theoretical study of an interaction-driven quantum phase diagram of twisted bilayer ${\mathrm{MoTe}}_2$ at hole filling factor ${\nu }_h=1$ as a function of twist angle $\theta$ and layer potential difference $V_z$, where $V_z$ is generated by an applied out-of-plane electric field. At $V_z=0$, the phase diagram includes quantum anomalous Hall insulators in the intermediate $\theta$ regime and topologically trivial multiferroic states with coexisting ferroelectricity and magnetism in both small and large $\theta$ regimes. There can be two transitions from the quantum anomalous Hall insulator phase to topologically trivial out-of-plane ferromagnetic phase, and finally to in-plane ${120}^{\circ }$ antiferromagnetic phase as $|V_z|$ increases, or a single transition without the intervening ferromagnetic phase. We show explicitly that the spin vector chirality of various ${120}^{\circ }$ antiferromagnetic states can be electrically switched. We discuss the connection between the experimentally measured Curie-Weiss temperature and the low-temperature magnetic order based on an effective Heisenberg model with magnetic anisotropy.

We study the role of the hyperfine interaction between nuclei and resident electrons in the formation of a three-pulse spin-dependent photon echo from self-assembled (In,Ga)As semiconductor quantum dots. In zero magnetic field we observe an oscillatory coherent optical response, which is detected in a time window of 10 ns, which is significantly longer than the radiative lifetime of trions of 0.26 ns. The oscillations occur due to spin precession of the resident electron spins in the effective fluctuating nuclear field, whose direction and magnitude are different in each quantum dot. We evaluate the mean field of nuclear spin fluctuations $\sqrt{\langle B_{\mathrm{N}}^2\rangle }=6.4$ mT. Owing to the specific mechanism of spin initialization, which depends on the direction and magnitude of the effective nuclear field, the spin-dependent photon echo extends the possibilities for exploring the hyperfine interaction in semiconductor quantum dots.

The spin Hall effect and its inverse have supported charge-spin conversion in spintronics for a long time, and a large spin Hall angle, which corresponds to the charge-spin conversion efficiency, is always needed for fast magnetic switching and energy conservation. Conventionally, the spin Hall angles in alloys are larger than those in pure metals with similar structures and elements, making them competitive candidates in spintronics. However, along with the introduction of disorder, the extrinsic spin Hall effect dominates and remains unclear because the corresponding sign could be different between experiments and theoretical calculations. Here, the first-principles-based scattering wave approach is used for binary ${\mathrm{Pt}}_x{\mathrm{Pd}}_{1-x}$ and ${\mathrm{Au}}_x{\mathrm{Ag}}_{1-x}$ alloys. The spin Hall effect therein is systematically studied, and the results reveal that the sign of the anomalous Hall angle can be changed by the components of the alloys in the dilute region due to the competition between different contributions. Our findings contribute to the understanding of the spin Hall effect in alloys and indicate that the localized clusters in dilute alloys should be the key to the sign difference in the spin Hall effect between theoretical and experimental results.

Ab initio molecular dynamics simulations are used to investigate the first-order liquid-liquid phase transition (LLPT) in molten sulfur recently observed in experiments [Henry et al., Nature (London) 584, 382 (2020)]. Our calculated pair correlation functions are in good agreement with the experimental results, and our simulations capture the structural change from low-density liquid (LDL) to high-density liquid (HDL). By studying the microstructure, it is found that this structural change is in fact one between two polymer phases with different degrees of order, with HDL having a higher degree of order than LDL. There are more ${\mathrm{S}}_8$ diradical structures in the long chain of LDL, but less in the long chain of HDL. This structural change may be related to the self-organized behavior of long-chain molecules in molten sulfur. However, no discontinuous change in density is found along the simulated isotherms, that is, the structural change based on ab initio calculations is continuous but not a first-order LLPT.

We study the single-particle properties of two-dimensional quasicrystals where the underlying geometry of the tight-binding lattice is crystalline but the on-site potential is quasicrystalline. We will focus on the two-dimensional (2D) generalized Aubry-André model which has a varying form to its quasiperiodic potential, through a deformation parameter and varied irrational periods of cosine terms, which allows a continuous family of on-site quasicrystalline models to be studied. We show that the 2D generalized Aubry-André model exhibits many single-particle mobility edges which we confirm for finite systems and supports critical states across large parameter regions. Critical states are neither fully localized nor extended. We observe that diagonal quasicrystalline models can support many energy intervals of critical states in the spectrum while stabilizing both localized and extended states in other energy intervals; we refer to these as anomalous mobility edges. We show that critical states are present independent of system size through a scaling analysis of the inverse participation ratio and that they are present in spectra that also contain extended and localized states, confirming that at least one anomalous mobility edge is present. Due to this, these models exhibit anomalous diffusion of initially localized states across the majority of parameter regions, including deep in the normally localized regime. The presence of critical states in large parameter regimes and throughout the spectrum will have consequences for the many-body properties of quasicrystals, including the formation of the Bose glass and the potential to host a many-body localized phase.

We study the nonequilibrium dynamics of the quantum sine-Gordon model describing a pair of Josephson-coupled one-dimensional bosonic quasicondensates. Motivated by experimentally accessible quench procedures where the zero mode of the quasicondensates is weakly coupled to finite momentum modes, we develop a Hamiltonian truncation scheme relying on a mini-superspace treatment of the zero mode (MSTHA). We apply this method to simulate the time evolution after both weak and strong quantum quenches, injecting a low or high energy density into the system, and we demonstrate that MSTHA accurately captures the dynamics from the hard-core boson limit to the experimentally relevant weakly interacting regime for sufficiently mild quenches. In the case of high energy densities, MSTHA breaks down for weak interaction but still extends the range of validity of previous Hamiltonian truncation schemes. We also compare these results to the semiclassical truncated Wigner approximation, and we establish that the dynamics can be well approximated by the semiclassical description in the weakly interacting regime realized in the experiments. In addition, we clarify the importance of the phononic modes depending on the sine-Gordon interaction strength.

We construct two free fermion lattice models exhibiting Hawking pair creation. Specifically, we consider the simplest case of a $d=1+1$ massless Dirac fermion, for which the Hawking effect can be understood in terms of a quench of the uniform vacuum state with a nonuniform Hamiltonian that interfaces modes with opposite chirality. For both our models, we find that additional modes arising from the lattice discretization play a crucial role, as they provide the bulk reservoir for the Hawking radiation: the Hawking pairs emerge from fermions deep inside the Fermi sea scattering off the effective black hole horizon. Our first model combines local hopping dynamics with a translation over one lattice site, and we find the resulting Floquet dynamics to realize a causal horizon, with fermions scattering from the region outside the horizon. For our second model, which relies on a purely local hopping Hamiltonian, we find the fermions to scatter from the inside. In both cases, for Hawking temperatures up to the inverse lattice spacing, we numerically find the resulting Hawking spectrum to be in perfect agreement with the Fermi-Dirac quantum field theory prediction.

We study magnetic properties of the half-filled Hubbard model on the two-dimensional $H_{00}$ hexagonal golden-mean quasiperiodic tiling. The tiling is composed of large and small hexagons, and parallelograms, and its vertex model is bipartite with a sublattice imbalance. The tight-binding model on the tiling has macroscopically degenerate states at $E=0$. We find the existence of two extended states in one of the sublattices, in addition to confined states in the other. This property is distinct from that of the well-known two-dimensional quasiperiodic tilings such as the Penrose and Ammann-Beenker tilings. Applying the Lieb theorem to the Hubbard model on the tiling, we obtain the exact fraction of the confined states as $1/2{\tau }^2$, where $\tau$ is the golden mean. This leads to a ferromagnetically ordered state in the weak coupling limit. Increasing the Coulomb interaction, the staggered magnetic moments are induced and gradually increase. Crossover behavior in the magnetically ordered states is also addressed in terms of perpendicular space analysis.

We propose a novel model which efficiently describes the magnetization dynamics in a magnetic bilayer system. By applying a particular gauge transformation to the Landau-Lifshitz-Gilbert (LLG) equation, we successfully convert the model into an exactly integrable framework. Thus the obtained analytical solutions allow us to predict a one-dimensional magnetic soliton pair existing by tuning the thickness of the spacing layer between the two ferrimagnetic layers. The decoupling-unlocking-locking transition of soliton motion is determined at various interaction intensity. Our results have implications for the manipulation of magnetic solitons and the design of theoretical magnetic soliton-based distance detection prototype.

We show that spin-orbit coupling at the interface between a superconducting film of the finite lateral size and the underlying ferromagnetic insulator with in-plane exchange field gives rise to a series of nonreciprocal effects provided the superconducting pairing is enhanced near the boundaries of the superconductor due to, e.g., variation of the film thickness or of the interlayer electron transparency. Specifically, the critical temperature and the critical depairing current are shown to depend on the relative orientation between the exchange field in the ferromagnet and the superconducting film boundaries. The discovered anisotropy of the superconducting properties is promising for the design of diode-type elements in superconducting spintronics.

Ising machines (IMs) have emerged as a promising solution for rapidly solving NP-complete combinatorial optimization problems, surpassing the capabilities of traditional computing methods. By efficiently determining the ground state of the Hamiltonian during the annealing process, IMs can effectively complement CPUs in tackling optimization challenges. To realize these IMs, a bistable oscillator is essential to emulate the atomic spins and interactions of the Ising model. This study introduces a Josephson parametric oscillator (JPO) based tile structure, serving as a fundamental unit for scalable superconductor-based IMs. Leveraging the bistable nature of JPOs, which are superconductor-based oscillators, the proposed machine can operate at frequencies of $\sim 7.5$ GHz while consuming significantly less power (by three orders of magnitude) than complementary metal-oxide semiconductor based systems. Furthermore, the compatibility of the proposed tile structure with the Lechner-Hauke-Zoller architecture ensures its viability for large-scale integration. We conducted simulations of the tile in a noisy environment to validate its functionality. We verified its operational characteristics by comparing the results with the analytical solution of its Hamiltonian model. This verification demonstrates the feasibility and effectiveness of the JPO-based tile in implementing IMs, opening new avenues for efficient and scalable combinatorial optimization in quantum computing.

We propose a comprehensive theoretical formulation of the magnetic penetration depth $\lambda \left(T\right)$ based on microscopic calculations for a general superconducting gap symmetry. Our findings admit the significant role of band structure and Fermi-surface topology together with the symmetry of the superconducting order parameter. We employ our findings pertaining to the heavy-fermion superconductor ${\mathrm{CeCoIn}}_5$ to explore both local (London) and nonlocal (Pippard) behaviors in response to an external magnetic field across varying temperatures. Our calculations in the low-temperature regime offer compelling macroscopic evidence of the nodal character within the superconducting state with $d_{x^2-y^2}$ symmetry. Furthermore, our findings align with the characteristics of Pippard-type superconductivity, holding significant implications for upcoming experiments.

${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te}$ has been synthesized and studied recently as a candidate topological superconductor. Its superconducting critical temperature increases with indium concentration. However, the role of indium in altering the normal-state band structure and generating superconductivity is not well understood. Here, we explore this question in ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te} (0<x<0.3)$ thin films, characterized by magnetotransport, infrared transmission, and photoemission spectroscopy measurement. We show that indium is forming an impurity band below the valence-band edge which pins the Fermi energy and effectively generates electron doping. An enhanced density of states due to this impurity band leads to the enhancement of $T_{\mathrm{c}}$ measured in multiple previous studies. The existence of the In impurity band and the role of In as a resonant impurity should be more carefully considered when discussing the topological nature of ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te}$.

More than 25 years ago, unexpected metallic behavior was discovered on the superconducting side of the superconductor-to-insulator transition. To this day, the origin of this behavior is unclear. In this work, we present resistance and broadband voltage noise measurements in the kilohertz regime in amorphous indium oxide. We find that the metallic behavior gives rise to excess noise much larger than what is expected from thermal noise with an unexpected frequency and temperature dependence whose origin remains elusive.

Ferroelectric germanium telluride is under active consideration for spintronic and thermoelectric applications. The control of the ferroelectric domain walls is a key issue to optimize the electronic and thermal properties of GeTe thin films. Domain walls properties are usually driven by the mechanical and electrostatic compatibility conditions of twin domains. However, in dense ferroelectric domain structures these compatibility conditions are hardly fulfilled everywhere. In particular intersection of domains may result in complex lattice relaxations and polarization textures. In this study, we have fabricated GeTe thin films on silicon substrate and elucidated the intersections of $a$-type domains using 3D reciprocal space maps, scanning tunneling microscopy, and second-harmonic microscopy. We demonstrate the presence of complex structural reorganizations that manifest by the formation of charged domain walls, large lattice rotations, and enhanced stretching of the rhombohedral lattice.

The scaling law of entanglement entropy could undergo qualitative changes during the nonunitary evolution of a quantum many-body system. In this work, we uncover such entanglement phase transitions for free fermions in one-dimensional non-Hermitian quasicrystals (NHQCs). We identify two types of entanglement transitions with different scaling laws and critical behaviors due to the interplay between non-Hermitian effects and quasiperiodic potentials. The first type represents a typical volume-law to area-law transition, which happens together with a PT-symmetry breaking and a localization transition. The second type features an abnormal log-law to area-law transition, which is mediated by a critical phase with a volume-law scaling in the steady-state entanglement entropy. These entangling phases and transitions are demonstrated in two representative models of noninteracting NHQCs. Our results thus advance the study of entanglement transitions in non-Hermitian disordered systems and further disclose the rich entanglement patterns in NHQCs.

We investigate the entanglement dynamics of the non-Hermitian Aubry-André-Harper chain. The results reveal that by increasing quasiperiodic strength, a phase transition occurs from the area law induced by non-Hermitian skin effect to the area law arising from Anderson localization. For the former, the entanglement entropy follows a nonmonotonic process, i.e., it increases first, then oscillates, and finally converges to a stable value while, for the latter, the entanglement entropy remains low because the wave function is not expandable in Anderson's localization region. The early-stage behavior of entanglement entropy indicates that the two area-law cases are of different phases. Interestingly, the volume-law behavior emerges at the critical point between these two area-law phases. Our study reveals that the area laws induced by the skin effect and the Anderson localization are two different phases, and that a volume law can emerge at the phase transition point. The understanding of the entanglement phase transition induced by disorder and skin effect is thus deepened.