The coexistence of out-of-plane and in-plane electric polarization is rare in two-dimensional (2D) ferroelectric materials, yet the two configurations offer distinct advantages for ferroelectric-based devices. Here, we report the coexistence of in-plane and out-of-plane incipient ferroelectricity, along with various phase transitions, in 2D van der Waals layered ${\mathrm{TlGaS}}_2$ single crystal. Detailed investigation of the incipient ferroelectric soft-mode behavior reveals a close correlation between the incipient ferroelectricity and the off-center displacement of $\mathrm{T}{\mathrm{l}}^{1+}$ ions with $6s^2$ lone pairs in ${\mathrm{TlGaS}}_2$. Anomalies near temperatures of about 75, 120, 180, and 220 K in infrared spectra, together with the absence of anomalies in the temperature-dependent specific heat, indicate the existence of local or weak long-range structural transitions in ${\mathrm{TlGaS}}_2$. Our results provide important experimental evidence for elucidating the phase transitions and coexistence of in-plane and out-of-plane incipient ferroelectricity in 2D layered ${\mathrm{TlGaS}}_2$.

How are the spatial and temporal patterns of information scrambling in locally interacting quantum many-body systems imprinted on the eigenstates of the system's time-evolution operator? We address this question by identifying statistical correlations among sets of minimally four eigenstates that provide a unified framework for various measures of information scrambling. These include operator mutual information and operator entanglement entropy of the time-evolution operator, as well as more conventional diagnostics such as two-point dynamical correlations and out-of-time-ordered correlators. We demonstrate this framework by obtaining numerical results for Floquet Haar-random circuits and by deriving exact results for eigenstate correlations in a minimal model of quantum chaos-Floquet dual-unitary circuits. These results reveal not only the butterfly effect and the information lightcone, but also finer structures of scrambling within the lightcone. Our work thus shows how the eigenstates of a chaotic system can encode the full spatiotemporal anatomy of quantum chaos, going beyond the descriptions offered by random matrix theory and the eigenstate thermalization hypothesis.

Layered transition metal dichalcogenides are an important platform for two-dimensional materials, where the inevitable intrinsic defects provide new degrees of freedom for tuning their physical properties. Based on first-principles calculations, this work systematically investigates the formation energies, charge states, and electronic structural characteristics of $V_{\mathrm{Pt}}, V_{\mathrm{Se}}$, and composite vacancies in monolayer ${\mathrm{PtSe}}_2$. The results indicate that while vacancy formation energies are highly sensitive to chemical potentials, the $V_{\mathrm{Se}}$ structure consistently exhibits the lowest formation energy. The charge defect calculation reveals the stable charge state intervals of $V_{\mathrm{Se}}$ and $V_{\mathrm{Pt}}$ as a function of the Fermi level, thus describing the evolution of the charge states of intrinsic vacancies at different electronic chemical potentials. Climbing Image Nudged Elastic Band calculations reveal high migration barriers for $V_{\mathrm{Se}}$ and $V_{\mathrm{Pt}}$, indicating strongly hindered vacancy diffusion at room temperature, while short ab initio Molecular Dynamics simulations confirm the absence of immediate structural collapse within the simulated time window. Optical property calculations indicate that point defects significantly alter the dielectric response of monolayer ${\mathrm{PtSe}}_2$ and generate new low-energy absorption channels associated with in-gap defect states. These findings provide new insights into defect-mediated electronic and optical property modulation in monolayer ${\mathrm{PtSe}}_2$, offering guidance for its potential device design.

We investigate the Anderson metal-insulator transition in three-dimensional lattices with systematically enhanced local connectivity. By introducing modified cubic lattices with seven- and eight-nearest neighbors (7NN and 8NN) per site, we tune the coordination number in a controlled manner while preserving dimensionality, symmetry class, hopping amplitude, and disorder statistics. Using exact diagonalization of a disordered tight-binding Hamiltonian, we characterize localization through complementary spectral and wave-function diagnostics, including level-spacing statistics and inverse participation ratio (IPR) scaling. Finite-size scaling analyses reveal disorder-driven metal-insulator transitions with critical disorder strengths that increase monotonically from the conventional simple cubic lattice to the 7NN and 8NN realizations. Remarkably, this enhancement cannot be explained by bandwidth broadening alone: The normalized ratio $W_c/B$ increases systematically with coordination number, demonstrating that local connectivity influences localization beyond simple spectral rescaling. Consistent with this interpretation, the modified 8NN lattice exhibits a critical disorder strength nearly identical to that of the conventional body-centered cubic lattice despite its fundamentally different connectivity geometry, suggesting that local connectivity can play an important role in determining the localization threshold, alongside bandwidth and detailed hopping geometry. Energy-resolved IPR maps further reveal mobility-edge-type behavior, showing that enhanced connectivity systematically enlarges the extended region of the spectrum and shifts localization crossover boundaries to higher disorder strengths. Despite these substantial changes in localization thresholds, the correlation-length exponent and multifractal properties remain consistent with the three-dimensional orthogonal universality class. These results demonstrate that controlled modification of local connectivity can provide a powerful route for tuning localization behavior in disordered quantum systems while preserving universal criticality.

Excited states play a central role in determining the physical properties of quantum matter, yet their accurate computation in many-body systems remains a formidable challenge for numerical methods. While neural quantum states have delivered outstanding results for ground-state problems, extending their applicability to excited states has faced limitations, including instability in dense spectra and reliance on symmetry constraints or penalty-based formulations. In this work, we rigorously formalize the framework introduced in [D. Pfau et al., Science 385, eadn0137 (2024)] in terms of Grassmann geometry of the Hilbert space. This allows us to generalize the Stochastic Reconfiguration method for the simultaneous optimization of multiple variational wave functions, and to introduce the multidimensional versions of operator variances and overlaps. We validate our approach on the Heisenberg quantum spin model on the square lattice, achieving highly accurate energies and physical observables for a large number of excited states.

We investigate the impact of quantum and thermal phase fluctuations on the suppression of superconducting order in two-dimensional systems. Within the two-dimensional quantum XY model in the phase representation, where on-site interaction terms govern quantum phase fluctuations, we perform extensive path-integral quantum Monte Carlo simulations. The resulting temperature-interaction phase diagram establishes the presence of a well-defined critical line ending at a quantum critical point at vanishing temperature with no indication of reentrant behavior. We further demonstrate that the resistance above the critical line reproduces the two expected different critical behaviors. For stronger interactions, above the quantum critical point, the system exhibits a crossover to an insulating regime at low temperatures. Finally, Monte Carlo calculations of current-current correlation functions enable us to extract the frequency-dependent conductivity in both superconducting and normal regimes, revealing a finite-frequency response that we attribute to quantum phase fluctuations.

Domain-wall-induced ferroic phases offer an emerging platform for reconfigurable nanoelectronics, yet their microscopic formation mechanisms and switching kinetics remain poorly understood. Here, combining machine-learning interatomic potentials with large-scale molecular dynamics simulations, we reveal that ferrielectric (FiE) phases can spontaneously emerge and grow extensively within antiferroelectric (AFE) ${\mathrm{PbZrO}}_3$ under modest biaxial compression. The AFE–FiE transition is driven by an entropy-dominated stabilization of the FiE structure and is enabled by an exceptionally low transformation barrier that collapses under strain. We further show that FiE domains exhibit polarization reversal via dipole flipping-assisted domain reshaping, featuring a small activation barrier and a robust P–E hysteresis response. These results establish the microscopic origin, energetic hierarchy, and switching pathways of DW-induced FiE phases, open an opportunity for their applications in high-speed, low-power domain-boundary-based nanoelectronic devices.

The search for candidate Kitaev materials has largely focused on $4d$ and $5d$ transition-metal compounds with various lattice geometries. In contrast, investigations of rare-earth $4f$ systems have thus far been restricted mainly to honeycomb and triangular lattices. In this work, we investigate the rare-earth-based double perovskites ${\mathrm{Ba}}_2{\mathrm{YbNbO}}_6$ and ${\mathrm{Ba}}_2{\mathrm{NdNbO}}_6$, which crystallize in a face-centered cubic structure. Magnetization and heat-capacity measurements establish isolated $j_{\mathrm{eff}}=1/2$ Kramers doublet ground states arising from strong spin-orbit coupling (SOC) and crystal electric-field effects, which are further supported by density functional theory calculations. Millikelvin-temperature thermodynamic measurements reveal long-range magnetic order with moderate frustration in both compounds. The emergence of magnetic order may be understood within an order-by-disorder scenario, as theoretically proposed for rare-earth fcc lattices with finite Kitaev interactions. Our results thus identify ${\mathrm{Ba}}_2{\mathrm{YbNbO}}_6$ and ${\mathrm{Ba}}_2{\mathrm{NdNbO}}_6$ as promising rare-earth spin-orbit-entangled magnets and motivate further experimental and theoretical investigations aimed at determining the complete exchange tensor to elucidate the microscopic origin of the underlying magnetic interactions.

We compare extensive ab initio simulations and embedded-atom-model molecular dynamics for analysis of collective dynamics in liquid Fe at several experimental pressures and temperatures of 2200 and 2700 K [Y. Kuwayama et al., Phys. Rev. Lett. 124, 165701 (2020)]. Dynamic eigenmodes of the generalized Langevin equation were calculated based on simulation data and analyzed in a wide range of wave numbers with a focus on dispersion of collective excitations. We analyze the origin of positive dispersion of sound excitations in connection with contributions from different types of hydrodynamic and nonhydrodynamic fluctuations to the corresponding eigenvectors. Dispersion of collective excitations and adiabatic speed of sound, estimated from the simulation data at three pressures, is compared to the values obtained from the inelastic x-ray scattering experiments.

MAX phase $\mathrm{T}{\mathrm{i}}_2\mathrm{SC}$ comes under the category of hexagonal ternary carbides whose room-temperature (RT) total thermal conductivity $\left({\kappa }_{\mathrm{T}}={\kappa }_{\mathrm{e}}+{\kappa }_{\mathrm{ph}}\right)$ is experimentally reported to be the highest amongst all in the 211 category and one of the highest values across the broader MAX-phase family. It shows anomalous temperature $\left(\mathrm{T}\right)$ dependence of ${\kappa }_{\mathrm{T}}$ at high $T$ over a broad range of temperatures. In this study, employing first-principles-based phonon-electron calculations, we quantify the contributions of both electron (${\kappa }_{\mathrm{e}}$) and phonon (${\kappa }_{\mathrm{ph}})$ separately to its thermal conductivity without considering the Sommerfeld value as the decoupling factor. We demonstrate that the weak temperature dependence of ${\kappa }_{\mathrm{T}}$ above RT arises from the comparable phonon-electron interaction relative to the phonon-phonon interaction, and the room-temperature contribution of ${\kappa }_{\mathrm{ph}}$ is 50% of the total thermal conductivity. The phonon-electron interaction is found to be higher throughout the whole frequency range compared to the anharmonic phonon-phonon interaction because of the large density of states around the Fermi energy, hence high metallicity, arising from two opposing types of interactions, antibonding $\mathrm{Ti}d\text{−}\mathrm{S}p$ and bonding $\mathrm{Ti}d\text{−}\mathrm{Ti}d$. The anharmonic phonon-phonon scattering rate is also noted to be higher in $\mathrm{T}{\mathrm{i}}_2\mathrm{SC}$ than in other group-d carbides due to significant cross-plane phonon-phonon coupling and an asymmetric bonding environment. At temperatures below 400 K, the electronic Lorenz number significantly deviates from its conventional Sommerfeld value. Despite the strong structural anisotropy in $\mathrm{T}{\mathrm{i}}_2\mathrm{SC}$, its electrical transport is isotropic, while thermal transport shows only weak anisotropy. This behavior originates from the compensation between group velocities and scattering rates either across different electronic bands and phonon modes, or between their energy-dependent directional averages.

We develop a self-energy-dressed Green's function framework for terahertz-induced phonon angular momentum in polar crystals. The rectified angular-momentum response is formulated as a second-order response and, within a dressed-bubble approximation, is expressed in terms of retarded phonon propagators weighted by mode-resolved polarization and angular-momentum matrix elements. Anharmonic self-energies enter through the dressed propagators, incorporating finite-temperature frequency renormalization and linewidth broadening directly into the response kernel. Applying this framework to wurtzite GaN, we show that the terahertz propagation direction and polarization select distinct rotational phonon channels: a nondegenerate ${\mathrm{E}}_1\left(\mathrm{TO}\right)\text{−}{\mathrm{A}}_1\left(\mathrm{TO}\right)$ channel with phase- and frequency-tunable angular momentum, and a degenerate ${\mathrm{E}}_1\left(\mathrm{TO}\right)$ channel with helicity-selected response. Anharmonic broadening suppresses and smooths the resonant structures while preserving the characteristic phase dependence of each channel. An order-of-magnitude estimate based on the phonon inverse Faraday-effect framework gives an mT-scale effective magnetic field for representative electron-phonon coupling strengths. This work places coherent terahertz-driven circular-phonon physics in a first-principles-based response framework and provides a starting point for going beyond constant-damping driven-mode descriptions.

The essence of the quantum anomalous Hall (QAH) effect is that, in the absence of an external magnetic field, the bulk of a material remains insulating while its boundaries host a quantized number of dissipation-free chiral edge channels determined precisely by the Chern number. A high Chern number signifies multiple parallel dissipationless transport pathways, dramatically boosting the efficiency of charge and information transfer. Here, we adopt stacking engineering to implement layer-degree-of-freedom-programmable QAH effects in the A-type antiferromagnetic topological insulator ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$. A perpendicular electric field drives the system reversibly between topologically nontrivial and trivial regimes and further induces a high-Chern-number quantum Hall state accompanied by a multilayer Hall effect, i.e., a robust bilayer current redistribution between surface and middle layers, extending tunability from single to dual layers. Floquet calculations show that circularly polarized light can suppress layer-resolved Hall response; the QAH state depends markedly on the light's helicity, with AB and BA stackings exhibiting opposite responses to left- and right-handed circular polarization. This work establishes a framework for electric- and optical-field control of layer Hall effects, offering materials-compatible theoretical routes and experimental protocols for ultra-low-power topological electronics, layer-resolved memory, and reconfigurable quantum devices.

We investigate the interplay between superconductivity and nematic order in a two-dimensional electron gas with competing pairing and quadrupolar forward-scattering interactions. The model includes both $s$-wave and $d$-wave superconducting channels. We compute the mean-field free energy density and determine the phase diagrams as functions of interaction strengths and temperature by solving a set of coupled self-consistent equations. At zero temperature, we find that the nematic order competes strongly with $d$-wave superconductivity, leading to a direct first-order phase transition, while its interplay with $s$-wave pairing allows for a coexistence phase characterized by an anisotropic Fermi surface with a uniform superconducting gap. At finite temperatures, quadrupolar interactions promote the emergence of additional superconducting components, giving rise to regimes where $s$-wave, $d$-wave, and nematic orders coexist. Our results highlight the role of symmetry and interaction strength in shaping the phase structure and provide a minimal framework to describe intertwined nematic and superconducting phases in correlated electron systems.

Unidirectional magnetoresistance, or electric magnetochiral anisotropy (eMChA), is a nonlinear magnetotransport effect emerging in noncentrosymmetric conductors. This phenomenon manifests as a resistance $R$ change proportional to the first power of both the electric current $\mathbf{I}$ and applied magnetic field $\mathbf{B}$. The eMChA contribution $\mathrm{\Delta }R\left(B\right)/R\left(0\right)$ takes distinct forms: (i) a chiral term, $2\chi \mathbf{I}·\mathbf{B}$, and (ii) a polar term, $2\gamma \mathbf{I}·(\mathbf{P}\times \mathbf{B})$, where $\mathbf{P}$ denotes the electric polarization and $\chi$ and $\gamma$ represent the respective eMChA coefficients. In Fontana et al. [Phys. Rev. Lett. 135, 106602 (2025)], we provided empirical evidence that the eMChA in the conduction band of tellurene is polar $(\chi =0,$ $\gamma \ne 0)$ and showed that it emerges from the quantum metric dipole associated with its Weyl node and from the lone pair polarization $\mathbf{P}$. Here, we extend this study to the valence band of tellurene, where the eMChA is commonly assumed to be chiral $(\chi \ne 0,\gamma =0)$. We show that a finite polar coefficient $\gamma \ne 0$ also emerges naturally through a downfolding procedure, in which remote Weyl-node-containing bands induce momentum-space gradients of the quantum metric in the low-energy levels, activating finite metric dipoles. Combining semiclassical Boltzmann transport with a $\mathbf{k}·\mathbf{p}$ description of tellurene, our numerical calculations agree quantitatively with doping $\left(\mu \right)$ dependent second-harmonic measurements of the longitudinal voltage $V_{\parallel }^{2\omega }\left(\mu \right)$ in perpendicular field. The combined chiral and polar characters $(\chi \ne 0,\gamma \ne 0)$ of the eMChA in tellurene also explains the shift in the angular $\left(\varphi \right)$ dependence of $V_{\parallel }^{2\omega }\left(\varphi \right)$ for in plane fields. Our results demonstrate that the polar eMChA can arise in topologically trivial bands through multiband effects and establish tellurene as a platform for quantum-geometric rectification in both electron and hole regimes.

We show that a hybrid moiré one-dimensional (moiré-1D) superlattice gives electrical control over whether a Dirac-Dirac momentum resonance opens a charge-neutrality gap, and through which mass channel. In twisted bilayer graphene subject to a layer-dependent unidirectional scalar potential, the charge-neutrality gap is controlled by the Fourier parity of the resonance-selected dressed interlayer harmonic: odd selected harmonics gap same-chirality Dirac-cone pairs, whereas even selected harmonics gap opposite-chirality pairs. A dressed-harmonic two-cone theory shows that this rule follows from two ingredients: the selected harmonic fixes the Pauli sector of the intercone matrix, and the dressed transverse velocities fix the relative chirality of the interacting cones. Because the 1D modulation can reverse the transverse velocity of one layer, it can electrically switch the relative chirality and hence the active mass channel, e.g., turning an even resonance from gapless to gapped. Full-wave continuum miniband calculations confirm both the exact-resonance rule and a finite near-resonant gapped window with quantitative fabrication tolerances. Far away from resonance, the same dressing yields strongly anisotropic but gapless Dirac bands. Hybrid moiré-1D superlattices therefore provide a route to programmable mass selection in coupled Dirac systems.

Orbital-free density functional theory (OFDFT) is a promising route to large-scale first-principles simulations, but its application to second-row covalent systems remains limited by the inaccurate description of localized, highly inhomogeneous densities and by the lack of angular-momentum dependence in conventional local pseudopotentials. Here, we develop a unified tight-binding orbital-free density functional theory framework that incorporates both nonlocal kinetic energy and nonlocal pseudopotential energy terms within the same reference-density expansion. In this formulation, a frozen reference density constructed from scaled atomic densities captures the dominant localized atomic contributions, while the self-consistent density variation accounts for bonding and environment-dependent effects. Meanwhile, the nonlocal pseudopotential energy density functional restores the angular-momentum-dependent electron-ion interactions essential for describing directional bonding. Benchmarks on representative B- and C-based covalent systems show that the proposed framework accurately reproduces the equation-of-state properties, relative energetics, and electron-density distributions of diverse boron allotropes while retaining the linear-scaling behavior of OFDFT. For carbon allotropes, the method captures the main structural and bonding trends, with remaining deviations mainly associated with the near-core kinetic energy density of dense $s{p}^3$ phases. These results establish a viable unified OFDFT framework for large-scale simulations of covalent materials and highlight the accuracy of near-core kinetic energy as a key challenge for further methodological development.

We introduce a Kapitza-like mechanism for the near-field radiative heat transfer and show that fast modulation of any parameter controlling the flux, such as the vacuum gap or a material response, produces a quadratic, time-averaged correction in the slow thermal dynamics. This correction splits into a frequency-independent static term and a low-pass dynamical term, yielding sizable modulation-induced temperature shifts and modified effective thermal conductances that can stabilize or destabilize the steady state. Applying the theory to gap modulation between SiC slabs, we derive analytical scaling laws and predict temperature shifts that are fully measurable with existing experimental platforms, requiring only readily accessible low modulation frequencies of order $\mathrm{\Omega }\approx {10}^4\mathrm{rad}/\mathrm{s}$. Our results establish a thermal analog of the Kapitza mechanism and provide a general route for controlling radiative heat flow in micro- and nanoscale platforms.

Blue phosphorene (BlueP) has attracted considerable attention, and Cu(111) has been widely explored as a potential growth substrate. However, although several experiments have interpreted phosphorus-derived phases on Cu(111) as BlueP or BlueP-related structures, the chemical identity and atomic registry of the early-stage stripe phases remain unresolved. Here, by combining first-principles calculations with systematic structural searches, we identify a ${\mathrm{Cu}}_3{\mathrm{P}}_2$ ribbonlike surface alloy as the lowest-energy candidate for these stripe phases within the explored configuration space, rather than a direct pure BlueP overlayer. The simulated scanning tunneling microscopy contrast of this model is consistent with the observed stripe features, while its registry with Cu(111) accounts for the reported orientation locking. We further show that ${\mathrm{Cu}}_3{\mathrm{P}}_2$ ribbons can be periodically stitched into longer-period Cu–P superstructures that are energetically favored among the structures considered. In contrast, direct BlueP formation on bare Cu(111) is less favorable than several low-energy Cu–P surface-alloy structures. These results clarify the atomic structure and orientation-locking mechanism of phosphorus-induced stripe phases on Cu(111) and provide an atomic-scale basis for understanding the subsequent coverage-dependent evolution of the P/Cu(111) system.