We introduce a general corner transfer matrix renormalization group algorithm tailored to projected entangled-pair states on the triangular lattice. By integrating automatic differentiation, our approach enables direct variational energy minimization on this lattice geometry. In contrast to conventional approaches that map the triangular lattice onto a square lattice with diagonal next-nearest-neighbor interactions, our native formulation yields improved variational results at the same bond dimension. This improvement stems from a more faithful and physically informed representation of the entanglement structure in the tensor network and an increased number of variational parameters. We apply our method to the antiferromagnetic nearest-neighbor Heisenberg model on the triangular and kagome lattice, and benchmark our results against previous numerical studies.

High harmonic generation (HHG) in the terahertz (THz) regime is an emerging field that has already provided new insights into fundamental low-energy processes in Dirac materials and high-$T_{\text{C}}$ superconductors. Here, we demonstrate THz harmonic generation across the Mott insulator-metal transition in rare-earth nickelates (${\mathit{R}\mathrm{NiO}}_3, R$ = rare-earth atom). The THz harmonic signal shows distinct characteristics in the three different accessible phases: the intensity of harmonics increases upon cooling in both the low-temperature antiferromagnetic (AFM) insulating and high-temperature paramagnetic (PM) metallic phases, while this trend is reversed in the intermediate PM insulating phase. Using single- and two-band Hubbard models, we find different dominant origins of the THz harmonics in different phases: strong spin-charge and orbital-charge coupling in the AFM insulating phase, intraband currents from renormalized quasiparticles with temperature-dependent scattering rate in the PM metallic phase, and the reduction of the charge carrier density due to the opening of the Mott gap in the PM insulating phase. These results and mechanisms significantly differ from those observed upon excitation in the optical regime. Our study lays the foundation for THz HHG physics in Mott and other strongly correlated systems and offers design principles for efficient THz HHG from these systems.

We systematically investigate the magnetic and electronic properties of the Janus-$\mathrm{C}{\mathrm{r}}_2\mathrm{NAs}$ monolayer. Spin-polarized density functional theory (DFT) calculations reveal that the Janus-$\mathrm{C}{\mathrm{r}}_2\mathrm{NAs}$ monolayer is an intrinsic 2D ferromagnetic half-metal with a high Curie temperature ($T_{\mathrm{C}}$) of approximately 960 K. Heyd-Scuseria-Ernzerhof (HSE) calculations further indicate that the spin-down channel exhibits an indirect band gap of 3.348 eV, achieving 100% spin polarization. Moreover, this material exhibits an in-plane magnetic anisotropy energy (MAE) of 0.626 meV/unit cell with a strong Dzyaloshinskii-Moriya interaction (DMI) of 1.200 meV. Both MAE and DMI can be further enhanced via compressive strain and/or hole doping. Notably, under −0.5 e/unit cell hole doping, the DMI increases by approximately 128% compared with electron doping at the same concentration. Detailed analyses at the atomic level show that the MAE is governed by As atoms ($p_x$ and $p_y$ orbitals). Atomic-layer-resolved DMI calculations and spin-orbit coupling energy difference ($\mathrm{\Delta }\mathrm{SOC}$) analysis also confirm that the $\mathrm{\Delta }\mathrm{SOC}$ of As atoms dominates in all cases except for hole doping. Atomistic spin dynamics simulations clearly reveal the evolution of topological spin textures from bimerons to skyrmions and demonstrate that hole doping combined with uniaxial strain greatly enriches the skyrmion population. This work not only uncovers the rich spintronic properties of the Janus-$\mathrm{C}{\mathrm{r}}_2\mathrm{NAs}$ monolayer but also identifies it as a promising candidate for high-temperature, tunable 2D spintronic devices.

Laser-absorber modes naturally occur in parity-time ($\mathcal{PT}$)-symmetric systems, where a pole and a zero of the scattering matrix coincide, enabling the system to operate simultaneously as a laser oscillator (or amplifier) and a coherent perfect absorber. Here, by leveraging the effective $\mathcal{PT}$ symmetry that emerges under evanescent-wave excitation, we realize the analog of laser-absorber modes for evanescent waves in anti-$\mathcal{PT}$-symmetric photonic heterostructures, characterized by complex permittivity and permeability satisfying $\varepsilon \left(-\mathrm{z}\right)=-{\varepsilon }^{*}\left(\mathrm{z}\right)$ and $\mu \left(-\mathrm{z}\right)=-{\mu }^{*}\left(\mathrm{z}\right)$, respectively. Building on this mode, we show that such anti-$\mathcal{PT}$-symmetric systems can strongly amplify evanescent waves incident from either side, while completely absorbing coherently incident evanescent waves with appropriate amplitudes and phases. Furthermore, together with the excitation-frequency tuning, this functionality enables extreme tunability of the energy transport carried by interfering evanescent waves between the excitation and the anti-$\mathcal{PT}$-symmetric structure in the presence of realistic material dispersion. This mode has also been extended to exhibit a unidirectional spectral singularity, producing infinite reflection of evanescent waves from one side and zero reflection from the other, while maintaining a reciprocal finite transmission. Our approach reveals a strategy to manipulate evanescent waves for extreme light-matter interactions grounded in non-Hermitian physics, with implications for functional devices and applications in sensing and communication.

This study examines time-dependent spin transport in magnetic heterostructures under alternating-current drive using a time-dependent spin diffusion framework. We show that the impedance of spin valves can transition from resistive to capacitive behavior when switched from parallel to antiparallel magnetic configuration, revealing a tunable dynamical response rooted in spin accumulation and relaxation. This mechanism enables high-frequency spintronic functionalities, including a proposed “spin resonator” that toggles between an LR damper and an LC resonator without relying on a conventional charge-based capacitor.

Layered honeycomb magnets have garnered significant attention recently for their exotic quantum phenomena due to the potential anisotropic, bond-dependent Kitaev interactions. However, distinguishing the roles of Kitaev interactions and the symmetry-allowed Dzyaloshinskii-Moriya interaction (DMI) remains challenging, since both mechanisms may lead to similar magnetic excitations and thermal transport properties. To tackle this challenge, using a ferromagnetic honeycomb insulator $\mathrm{V}{\mathrm{I}}_3$ as a model system, we systematically study the angular-dependent thermal Hall conductivity $K_{\mathrm{xy}}$(θ, Φ) with both out-of-plane (θ) and in-plane (Φ) magnetic field rotations. Our results reveal a persistent thermal Hall response for both out-of-plane and in-plane rotating magnetic fields, devoid of the sign-reversal patterns characteristic of Kitaev physics. Instead, quantitative analysis shows that the angular-dependent $K_{\mathrm{xy}}$(θ, Φ) is governed by the projection between the magnetic moment and a tilted DM vector containing both out-of-plane and in-plane components. These results not only establish the DMI-driven topological magnetic excitations as the origin of the thermal Hall response in $\mathrm{V}{\mathrm{I}}_3$, but they also highlight the angular-dependent thermal Hall effect measurements as an effective approach for distinguishing competing interactions in quantum magnets.

The Family-Vicsek scaling is a fundamental framework for understanding surface growth in nonequilibrium classical systems, providing a universal description of temporal surface roughness evolution. Whether such scaling extends to strongly correlated quantum many-body systems—where dynamics are governed by unitarity, conservation laws, and quantum statistics—remains an open question. Here, we investigate the infinite-temperature dynamics of one-dimensional $SU\left(N\right)$ spin chains, focusing on the well-known $SU\left(2\right)$ XXZ model and the $SU\left(3\right)$ Izergin-Korepin model. We compute the quantum analog of classical surface roughness using the second cumulant of spin fluctuations and demonstrate Family-Vicsek scaling with respect to time and subsystem size. Crucially, we show that the scaling behavior is controlled by both integrability and non-Abelian global symmetries. We identify distinct transport regimes characterized by the dynamical exponent $z$: (i) ballistic transport with $z=1$, (ii) superdiffusive transport with the Kardar-Parisi-Zhang exponent $z=3/2$, and (iii) diffusive transport with the Edwards-Wilkinson exponent $z=2$. Notably, breaking integrability always drives the system into the diffusive regime. Our results demonstrate that Family-Vicsek scaling extends beyond classical systems, and emerges across quantum many-body models with $SU\left(N\right)$ symmetry.

We present direct experimental evidence of a weakly coupled multiband superconducting state in the bilayer iron-based superconductor ${\mathrm{ACa}}_2{\mathrm{Fe}}_4{\mathrm{As}}_4{\mathrm{F}}_2$ (A = K, Cs) via ultrahigh-resolution angle-resolved photoemission spectroscopy (ARPES). Remarkably, the K-containing compound exhibits two distinct transition temperatures, corresponding to two separate sets of bilayer-split bands, as evidenced by temperature-dependent superconducting gap and spectral weight near the Fermi energy, while its Cs counterpart displays conventional single transition behavior. These experimental observations are well described by the weakly coupled two-band model of Eilenberger theory, which identifies suppressed interband pairing interactions between the bilayer-split bands as the key mechanism. By exploring quantum phenomena in the weak-coupling limit within a multiband system, our findings pave the way for engineering exotic superconductivity via band-selective pairing control.

The coordination environment is a central issue in condensed matter physics and planetary science, as it governs structural diversity and physical properties under extreme conditions. In particular, hypercoordinate states of silicon—one of the most abundant elements in the universe—are key to understanding both the mineralogy of planetary interiors and the limits of chemical bonding theory beyond the octet rule. Here, we extend the concept of “chemical pressure,” originally developed in materials science, to planetary environments by investigating the interaction between $\mathrm{C}{\mathrm{O}}_2$ and $\mathrm{Si}{\mathrm{O}}_2$. Our first-principles calculations reveal that $\mathrm{C}{\mathrm{O}}_2$ can chemically compress $\mathrm{Si}{\mathrm{O}}_2$ and stabilize a novel eightfold-coordinated silicon carbonate, $\mathrm{Si}\mathrm{C}{\mathrm{O}}_4$, in the pressure range of 560–780 GPa. This stabilization occurs nearly 100 GPa earlier than in pure $\mathrm{Si}{\mathrm{O}}_2$ (∼650 GPa), representing a recombination of $\mathrm{Si}{\mathrm{O}}_2$ and $\mathrm{C}{\mathrm{O}}_2$ at megabar conditions after their decomposition above 26 GPa. As major constituents of planetary interiors, such Si-C-O compounds may influence carbon sequestration, migration, and release within planets. Moreover, $\mathrm{Si}\mathrm{C}{\mathrm{O}}_4$ exhibits lower density and higher thermal conductivity than $\mathrm{Si}{\mathrm{O}}_2$, suggesting enhanced heat transport and accelerated cooling processes in planetary interiors. These findings enrich the high-pressure phase diagram of the Si-C-O system and provide insights into planetary evolution and the fundamental limits of bonding under extreme compression.

We investigate the critical behavior of the one-dimensional Ising model with long-range interactions using the functional renormalization group in the local potential approximation (LPA), and compare our findings with Dyson's hierarchical model (DHM). While the DHM lacks translational invariance, it admits a field-theoretical description closely resembling the LPA, up to minor but nontrivial differences. After reviewing the real-space renormalization group approach to the DHM, we demonstrate a remarkable agreement in the critical exponent $\nu$ between the two methods across the entire range of power-law decays $1/2<\sigma <1$. We further benchmark our results against Monte Carlo simulations and analytical expansions near the upper boundary of the nontrivial regime, $\sigma \lesssim 1$.

${\mathrm{RuO}}_2$, a transition metal oxide, is gaining attention in spintronics because of its potential altermagnetic properties that affect spin-current behavior. Moreover, its capability to generate strong spin-orbit torques and significant spin Hall effects makes it a promising candidate for energy-efficient magnetic memory and logic devices. Additionally, the tunable thickness and crystallinity of ${\mathrm{RuO}}_2$ thin films enhance torque efficiency, enabling low-power magnetization switching. Spin pumping—a versatile technique for probing spin dynamics in quantum materials with high spin-orbit coupling—has attracted significant interest because of its straightforward, noninvasive nature and its effectiveness in overcoming impedance mismatch while enabling direct measurement of spintronic parameters. We present a systematic and detailed analysis of efficient spin-to-charge conversion in (110)-oriented ${\mathrm{RuO}}_2$ films, using amorphous CoFeB as the spin source. The spin Hall angle and spin-diffusion length are estimated to be $0.14\pm 0.01$ and $4.58\pm 0.40$ nm, respectively. A spin Hall conductivity of $998.89\pm 58.23\frac{\hslash }{e}{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$ is obtained, consistent with theoretical predictions. The interfacial spin transparency is evaluated to be $90\%$, while spin memory loss at the ${\mathrm{RuO}}_2/\mathrm{CoFeB}$ interface is found to be only $15\%$, indicating minimal spin scattering at the interface.

We introduce an extension of the time-dependent variational Monte Carlo (tVMC) method that adaptively controls the expressivity of the variational quantum state during the simulation of the dynamics. This adaptive tVMC (atVMC) approach is specifically designed to enhance numerical stability when overparameterized variational ansätze lead to ill-conditioned equations of motion. Building on the concept of the local-in-time error (LITE)—a measure of the deviation between variational and exact evolution—we introduce a procedure to quantify each parameter's contribution to reducing the LITE, using only quantities already computed in standard tVMC simulations. These relevance estimates guide the selective evolution of only the most significant parameters at each time step, while maintaining a prescribed level of accuracy. We benchmark the algorithm on quantum quenches in the one-dimensional transverse-field Ising model using both spin-Jastrow and restricted Boltzmann machine wave functions, with an emphasis on overparameterized regimes. The adaptive scheme significantly improves numerical stability and reduces the need for strong regularization, enabling reliable simulations with highly expressive variational ansätze.

Understanding and controlling coupled ionic-polaronic dynamics is crucial for optimizing the electrochemical performance in battery materials. However, studying such coupled dynamics remains challenging due to the intricate interplay between Li-ion configurations, polaron charge ordering, and lattice vibrations. Here, we develop a fine-tuned machine-learned force field (MLFF) for ${\mathrm{Li}}_x{\mathrm{FePO}}_4$ that captures the coupled ion-polaron behavior. Our simulations reveal picosecond-scale polaron hops occurring orders of magnitude faster than Li-ion migration, featuring strong correlation to Li configurations. Notably, polaron charge fluctuations are further enhanced at Li-rich/Li-poor phase boundaries, suggesting a potential interfacial electronic conduction mechanism. These results demonstrate the capability of fine-tuned MLFFs to resolve complex coupled transport and provide insight into emergent ionic-polaronic dynamics in ${\mathrm{Li}}_x{\mathrm{FePO}}_4$ and related multivalent cathode materials.

Thermalization and information scrambling in out-of-equilibrium quantum many-body systems are deeply intertwined: Local subsystems dynamically approach thermal density matrices while their entropies track nonlocal information spreading. Projected ensembles, i.e., ensembles of pure states conditioned on measurement outcomes of complementary subsystems, provide higher-order probes of thermalization, converging at late times to universal maximum-entropy ensembles constrained by conservation laws. In this work we introduce the partial projected ensemble (PPE) as a framework to study how the spatiotemporal structure of information scrambling is imprinted on projected ensembles. The PPE consists of an ensemble of mixed states induced on a subsystem by measurements on a spatially separated part of its complement, while tracing out the remainder, naturally capturing scenarios involving discarded outcomes or noise-induced losses. We show that the statistical fluctuations of the PPE faithfully track the causal lightcone of information spreading, thereby revealing how scrambling dynamics is encoded in the ensemble structure. In addition, we demonstrate that the probabilities of bit-string probabilities (PoPs) associated with the PPE exhibit distinct dynamical regimes and provide an experimentally accessible probe of scrambling. Both the PPE fluctuations and PoPs display exponential sensitivity to the size of the discarded region, reflecting an exponential degradation of quantum correlations under erasure or loss. We substantiate these findings using the nonintegrable kicked Ising chain, combining numerics in the ergodic regime with exact results at its self-dual point, and extend our analysis to the many-body localized (MBL) regime using simulations supported by analytical results for the $\ell$-bit model. The linear and logarithmic light cones characteristic of ergodic and MBL regimes, respectively, emerge naturally from the PPE dynamics, establishing it as a powerful tool for probing scrambling and deep thermalization.

An ab initio approach is presented for studying the collective excitations in excitonic insulators, charge/spin density waves, and superconductors. We derive the Bethe-Salpeter equation for the particle-hole excitations in the quasiparticle representation, from which the collective excited states are solved and the corresponding order parameter fluctuations are computed. This method is demonstrated numerically for the excitonic insulating phases of the biased ${\mathrm{WSe}}_2\text{−}{\mathrm{MoSe}}_2$ bilayer. It reveals the gapless phase mode, the subgap Bardasis-Schrieffer modes, and the above-gap scattering states. Our work paves the way for quantitative predictions of excited state phenomena from first-principles calculations in electronic systems with spontaneous symmetry breaking.

In this work, the hydrogenation performances of nonmetal sites in the transition metal dichalcogenides with the stoichiometry of $M{\mathit{X}}_2$ are systematically investigated using the first principles calculations. The trained machine learning model demonstrates that the $p_{\mathrm{z}}$ band center, bandgap, and the intrinsic nature of $X$ atoms are the key factors influencing the HER activity of $\mathit{M}{\mathit{X}}_2$. Furthermore, it also reveals that the observed relations between the $p_{\mathrm{z}}$ band center and HER activity in the semiconductorlike materials do not follow the scaling law, which originates from the bandgap-induced downshift of bonding and antibonding states. In addition to the bandgap, the intrinsic $p$ orbital energy level of the nonmetal atoms also contributes to the translation of $p_{\mathrm{z}}$ band center. Extended calculations indicate that the descriptor is equally applicable to the other catalysts, suggesting its universality in predicting the HER activity of nonmetal sites.

We apply perturbation theory of boundary conditions, originally developed by A.B. Migdal and independently by S.A. Moszkowski for deformed atomic nuclei, to finding eigenfrequencies of Raman-active spheroidal modes of a spheroid from those of a sphere and compare the outcomes with the results of numerical calculations for CdSe and silver nanoparticles. The modes are characterized by the total angular momentum $j=2$ and are fivefold degenerate for a sphere but split into three distinct modes, characterized by the absolute value of the total angular-momentum projection onto the spheroidal axis, in the case of a spheroid. The perturbation method works well in the case of the rigid boundary conditions, with the displacement field set to zero at the boundary, and accurately predicts the splittings when the spheroidal shape is close to a sphere, but fails in the case of the stress-free boundary conditions.

Understanding the structure-property relationships and structural evolution under external stimuli is critical for developing high-performance lead-free antiferroelectric energy storage ceramics, while the underlying physics mechanism remains ambiguous. Here, the structural evolution, phonon behavior, structural heterogeneity, and optical transitions in $(1-x)\left(0.7{\mathrm{AgNbO}}_3\text{−}0.3{\mathrm{NaNbO}}_3\right)\text{−}x{\mathrm{Sr}}_{0.7}{\mathrm{Bi}}_{0.2}{\mathrm{TiO}}_3$ (AN-NN-SBT) energy storage ceramics through advanced spectroscopy techniques have been studied. Doping with ${\mathrm{Sr}}_{0.7}{\mathrm{Bi}}_{0.2}{\mathrm{TiO}}_3$ (SBT) induces lattice distortion via ionic radius mismatch, driving a phase transition from antiferroelectric to paraelectric states. The optical band gap ($E_g$) is broadened and the breakdown strength is enhanced, owing to the concomitant formation of Ti-O bonds, vacancy creation, and orbital hybridization. Furthermore, temperature-dependent Raman analyses reveal reversible phase transitions ($M\text{−}O\text{−}T$) governed by phonon merging, abnormal frequency shift, and soft mode suppression. Thermal modulation induces nonlinear $E_g$ narrowing, attributed to synergistic effects of lattice thermal expansion and electron-phonon interactions. Importantly, the phase coexistence and structure evolution process with temperature were discovered by in situ Raman mapping directly. A composition-critical temperature phase diagram was established, demonstrating that SBT doping reduces the structural transition temperatures and enables the $M_3/O$ phase boundary at room temperature in the AN-NN-SBT20 system, which in turn yields optimal energy storage performance. These findings elucidate the interplay between lattice symmetry, electronic properties, and energy storage performance, providing a strategic framework for designing high-performance lead-free energy storage ceramics.