The discovery of infinite-layer nickelate superconductors has generated great enthusiasm for exploring new nickelate superconductors with higher $T_{\mathrm{c}}$ and further elucidating their superconducting mechanism. In this work, we systematically investigate the pressure effect on both the normal state and superconductivity of ${\mathrm{La}}_{0.8}{\mathrm{Sr}}_{0.2}{\mathrm{NiO}}_2$ thin film by measuring resistance under various hydrostatic pressures up to 7.5 GPa. The results show that $T_{\mathrm{c}}$ exhibits a monotonic increase from $T_{\mathrm{c}}^{\mathrm{onset}}\sim 19$ K at ambient pressure to $T_{\mathrm{c}}^{\mathrm{onset}}\sim 26$ K at 7.5 GPa. Moreover, normal-state resistance displays linear behavior in the measured pressure range, which is a hallmark of the strange metal state. The constructed temperature-pressure phase diagram reveals a potentially universal linear enhancement of $T_{\mathrm{c}}$ in infinite-layer nickelate superconductors at nearly optimal doping. This indicates that the evolution of $T_{\mathrm{c}}$ can be affected by multiple factors and can be further enhanced by pressure, epitaxial stress, or substitution of rare-earth metals. Our work provides critical insights for further enhancing $T_{\mathrm{c}}$ and constructing theoretical models to explore the superconducting mechanism in infinite-layer nickelate systems.

Borophene, an outstanding platform to elucidate the structure-property relationship, possesses diverse concentration and spatial arrangement of hexagonal vacancies (HVs) owing to its structural polymorphism. Here, we study electron transport in disordered borophene nanoribbons (BNRs) with two types of HVs distributed randomly on a triangular lattice, namely, unrestricted HVs and restricted ones. Unrestricted HVs which distribute stochastically at all spatially allowed sites function as strong scatterers and lead to Anderson localization over the entire energy spectrum. In contrast, confining HVs to predefined sites separated by a fixed distance preserves quantized conductance peaks associated with resonant tunneling, although the overall transmission ability is reduced. The magnitude of these quantized resonant peaks is robust against the HV probability, nanoribbon length, disorder configuration, and inhomogeneous model parameters, while their position and number are tunable via the fixed distance and nanoribbon width. Remarkably, the transmission ability around resonant energies could be enhanced by the HV probability, revealing a counterintuitive regime of HV-enhanced electron transport. The underlying physics can be understood from local current distributions and wave-function analysis, indicating the emergence of distinct transmission modes arising from specific arrangement of HVs. In particular, we reveal a resonant mechanism mediated by extended states whose amplitudes strictly vanish at predefined HV sites, rendering electronic transport entirely unaffected by defect scattering. These results establish HV engineering as an alternative route to manipulate quantum transport in disordered BNRs, with potential relevance to other triangular lattices, such as transition-metal dichalcogenides and moiré materials.

We systematically investigate the entanglement and information dynamics of quasiperiodic systems across their extended, critical, and localized phases, aiming to identify dynamical signatures that can reveal the multifractal spatial structure of critical states and distinguish critical phases from the extended and localized regimes. Focusing on the generalized Aubry-André-Harper model, we complement the half-chain entanglement entropy with the spatially resolved subsystem information capacity (SIC) and demonstrate that critical states exhibit pronounced spatial heterogeneity absent in the extended and localized phases. In the steady state, the SIC reveals a stepwise ramp as a function of subsystem size, reflecting an underlying fragmentation of the chain into weakly connected subregions. Dynamically, information initially localized within such a subregion can undergo coherent long-lived oscillations, dubbed subregion echoes, whose period scales with the subregion length, in quantitative agreement with a quasiparticle picture of confined quasiparticle reflections. We trace this internal fragmentation to the incommensurately distributed zeros (IDZs) in the off-diagonal hopping terms of the Hamiltonian. To establish the generality of the SIC as a diagnostic tool, we further apply it to a mobility-edge phase with coexisting extended and localized states and to a critical phase that does not originate from IDZ fragmentation, and show that the SIC can cleanly distinguish these scenarios through their distinct steady-state profiles, initial-site sensitivities, and the presence or absence of subregion echoes. Our results demonstrate that the SIC serves as a powerful real-space probe for diagnosing critical phases and uncovering the bottlenecked connectivity that underlies the multifractal structure of critical states.

Spin-orbit torque (SOT), which enables electrical control of magnetization, plays a crucial role in the development of next-generation spintronic devices. Realizing SOT in two-dimensional van der Waals systems, together with achieving efficient nonvolatile manipulation via ferroelectricity, would be highly beneficial for the implementation of tunable logic devices with enhanced storage density. In this work, based on first-principles calculation and using a multiferroic ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2/{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure as a representative example, we demonstrate that switching the ferroelectric polarization of the ${\mathrm{In}}_2{\mathrm{Se}}_3$ layer induces a pronounced modification in the magnetization-dependent distribution of torkance within the heterostructure. Specifically, when the magnetization is along the in-plane direction, where the torque is maximal, reversing the polarization of ${\mathrm{In}}_2{\mathrm{Se}}_3$ from upward to downward enhances the total torkance to more than 150% of its original value. This substantial variation primarily originates from the polarization-induced modulation of the $z$ component of the time-reversal-odd torkance, which is mainly associated with an approximately 233% change in the atomic-resolved torque contributed from the middle Fe layer in ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$ layers. Further analysis reveals that the electronic states near $\mathrm{\Gamma }$ on the Fermi surface undergo significant reconstruction upon polarization switching, which is responsible for the observed variation in the time-reversal-odd torque. Our results not only provide unique insights into the functional potential of van der Waals multiferroic heterostructures but also offer a viable strategy for achieving electrically tunable SOT, paving the way for future programmable spintronic devices.

We demonstrate the stray-field-mediated skyrmion stabilizing capabilities of ultrathin exchange-decoupled antisymmetric ferromagnetic bilayers based on conventional transition metal materials. Using an asymptotically exact micromagnetic model valid in the ultrathin film limit, we show that the antisymmetric tailoring of the bilayer allows the Dzyaloshinskii-Moriya interaction and the dipolar interaction to act synergistically to stabilize skyrmions, in contrast to the monolayer case, in which these energies compete. To obtain optimal stability of these skyrmions against collapse and bursting—the two fundamental processes determining skyrmion lifetime, we carry out an asymptotic analysis of the saddle point solution that separates the skyrmion from the demagnetized state. The result is an optimal stability line for compact skyrmions in the nondimensional parameter space of the effective Dzyaloshinskii-Moriya interaction strength and the effective film thickness. Our predictions are confirmed by extensive micromagnetic simulations of antisymmetric bilayers, using magnetic parameters of the conventional $\mathrm{Pt}/\mathrm{Co}/{\mathrm{AlO}}_x$ systems. Our results may provide a new pathway for experimental observations of 10-nm-radius zero-field skyrmions with lifetimes compatible with information technology applications.

The low-temperature thermodynamic properties and magnetic structure of the garnet oxide ${\mathrm{Mn}}_3{\mathrm{V}}_2{\mathrm{Ge}}_3{\mathrm{O}}_{12}$ (MVGO) have been investigated via magnetic susceptibility, specific heat, and neutron diffraction measurements. MVGO exhibits two successive magnetic transitions at $T_{\mathrm{N}1}=4\mathrm{K}$ and $T_{\mathrm{N}2}=2.6\mathrm{K}$, associated with the antiferromagnetic ordering of noncollinear ${\mathrm{Mn}}^{2+}$ and collinear ${\mathrm{V}}^{3+}$ sublattices, respectively. The Curie-Weiss analysis based on the susceptibility data and the magnetic entropy derived from the specific heat measurement confirmed the ground state $S=5/2$ for ${\mathrm{Mn}}^{2+}$ and $S=1$ for ${\mathrm{V}}^{3+}$. Density functional theory calculations reproduce the experimentally determined magnetic structures, yielding nearest-neighbor antiferromagnetic couplings $J_{\text{Mn-Mn}}$ and $J_{\text{V-V}}$ along with a ferromagnetic coupling $J_{\text{Mn-V}}$. By applying a magnetic field, we construct a temperature-field phase diagram for MVGO that encompasses multiple distinct phases. These results establish MVGO as a complex system among garnet-structure magnets.

Alternating (AC) magnetic fields can induce not only an alternating magnetization in materials, but also an alternating temperature via the magnetocaloric effect. The latter effect is typically neglected when performing AC susceptibility measurements, but consideration of both effects on an equal footing is necessary in order to reliably distinguish between internal and external causes of magnetic response and accurately extract quantitative information about relaxation processes. In order to address this, we have developed a method to measure the AC magnetocaloric effect that is compatible with AC susceptibility measurements, and also a framework to analyze these data in combination. We demonstrate the efficacy of this approach using ${\mathrm{YbVO}}_4$, a material for which strong single-ion anisotropy leads to slow electronic spin-lattice relaxation at low temperatures via a phonon bottleneck effect. We report AC magnetic susceptibility and AC magnetocaloric effect measurements for this material as a function of field and frequency at a temperature of 3 K. We analyze the data using a discretized thermal model, and extract the field dependence of the intrinsic spin-lattice relaxation rate. This demonstration experiment illustrates a general approach to quantitatively address multiple measured quantities in driven systems using a unified thermal circuit analysis. The thermal analysis methods presented in this report can be extended to study other magnetic, dielectric, and elastic materials exhibiting a complex response to an external driving field in the presence of internal and external relaxation, particularly when an energy dissipation process is within an accessible frequency regime.

An effective dynamical equation for the magnetization of a nanomagnet with surface anisotropy is derived from an atomistic spin Hamiltonian using the spin coherent-state path integral formalism. The derivation proceeds in two steps. First, the continuum Euclidean action for the many-spin nanomagnet is obtained, including the Wess-Zumino-Witten (Berry phase) term, as well as exchange, Zeeman, and core/surface anisotropy contributions. Second, the local magnetization density is decomposed into a slowly varying macrospin component and transverse spin-misalignment fluctuations driven by surface effects. A systematic expansion of the action is then performed up to quadratic order in the transverse-fluctuation variables. Under the adiabatic approximation, where transverse modes relax much faster than the macrospin, these modes are eliminated using their static Green's-function solution. This results in a closed, extended Landau-Lifshitz equation for the macrospin, featuring an effective field with nontrivial corrections from spin misalignment. These corrections renormalize both the Zeeman and anisotropy fields and introduce additional terms that act as nutation- and damping-like contributions. For a spherical nanoparticle with Néel surface anisotropy, the leading surface-induced correction is explicitly evaluated, and its structure is compared to inertial extensions of the Landau-Lifshitz-Gilbert equation. Together, these results establish a microscopic foundation for surface-induced magnetization nutation in nanomagnets and provide a framework to estimate corrections to the precession frequency and effective damping. The corresponding shift in the ferromagnetic-resonance frequency and linewidth is measurable with standard GHz spectrometers, and the underlying adiabatic-elimination mechanism is expected to generalize to any slow magnetic variable coupled to a bath of fast fluctuating modes.

Orbital-free density functional theory (OFDFT) has reemerged as a viable alternative to Kohn-Sham DFT, driven by recent advances in kinetic energy density functionals (KEDFs). Nonlocal KEDFs have significantly extended OFDFT's applicability, particularly for bulk solids, but their high computational cost and dependence on system-specific parameters limit their universality. In this work, we propose a semilocal KEDF at the generalized gradient approximation level that achieves accuracy comparable to the state-of-the-art semilocal functionals while remaining parameter-free. Our construction revives the Thomas-Fermi–von Weizsäcker (TFvW) framework by modulating the relative contributions of TF and vW terms through physically motivated constraints and preserving the exact second-order gradient expansion. Despite its simple form, the proposed functional (KGE2) performs well across both extended systems (metals and semiconductors) and finite systems (clusters), without any need for empirical tuning. These results mark a step toward the development of transferable and computationally efficient semilocal KEDFs for large-scale OFDFT simulations.

We present a comprehensive first-principles investigation of all symmetrically inequivalent low-index surfaces of $\beta \text{−}{\mathrm{Ga}}_2{\mathrm{O}}_3$, examining their structural properties and thermodynamic stability across experimentally relevant growth conditions. Using density-functional theory with both the semi-local functional PBEsol and a modified PBE0 hybrid functional with $26\%$ exact exchange, denoted PBE0(0.26), we calculate surface free energies for the (010), (100), (001), ($\overline{2}01$), (110), (111), and ($11\overline{1}$) orientations, including the effects of harmonic vibrational contributions and varying oxygen chemical potentials. We demonstrate that the energetic ordering remains consistent across computational approaches and that the vibrational contributions remain below $0.2\mathrm{J}/{\mathrm{m}}^2$ up to temperatures of $1000\mathrm{K}$. A coordination-based model that correlates surface stability with the density of undercoordinated atoms reveals that undercoordinated oxygen atoms and tetrahedral Ga sites substantially destabilize surfaces, while exposed undercoordinated octahedral Ga atoms serve as indicators of surface stability. Our thermodynamic analysis shows that stoichiometric terminations dominate over nearly the entire range of chemical potentials relevant for $\beta \text{−}{\mathrm{Ga}}_2{\mathrm{O}}_3$ stability, while nonstoichiometric terminations emerge only under extreme reducing or oxidizing conditions. Notably, we predict the formation of stable Ga-rich terminations resembling Ga adlayers for the (100) and ($\overline{2}01$) surfaces under highly reducing conditions.

Topological invariants govern many important physical properties in condensed matter systems. In this work, we obtain the complete set of topological invariants for a family of one-dimensional quasicrystals. The first and best-studied member of the family is the Fibonacci chain, while the successive ones are known in the literature as silver, bronze, etc., and collectively as the metallic mean chains. By considering rational approximants, and by making use of the relationship between these chains and two-dimensional Quantum Hall problems, we write down a gap labeling scheme for finite systems, and extend it to the quasiperiodic limit. We show, by numerical computations on open chains, that the proposed scheme correctly yields the winding numbers of edge states in each of the gaps, in all of the quasicrystals. We observe that their relationship to the two-dimensional model leads, in the strict one-dimensional chains family, to spectra forming a simplified Hofstadter “butterfly” diagram, with the analogs of Landau levels appearing in the asymptotic limit. These topological invariants for noninteracting 1D chains can be expected to remain pertinent for superconducting systems where Majorana or Aharanov bound states occur, as shown in recent studies of interacting or Josephson coupled Fibonacci chains.

We theoretically introduce a quasi-one-dimensional magnetic heterostructure of alternating 2D topological and normal insulator strips. Such a structure can be realized by special fabrication techniques or may emerge naturally in twisted bilayers of certain transition metal dichalcogenides. Its low-energy physics is governed by a hybrid Hamiltonian intertwining the Su-Schrieffer-Heeger and Shockley models, with spin-momentum locking and local Zeeman splitting. Symmetry analysis places it in class AIII, characterized by chiral symmetry and a $\mathbb{Z}$ topological invariant. Computing the winding number from the block-off-diagonal structure of the Hamiltonian reveals topological phases characterized by invariants $\nu =0$, 1, and 2. Furthermore, a single magnetic defect acts as a sensitive local probe, whose in-gap spectrum provides a spectroscopic fingerprint to distinguish global topological phases. We show that the frequency-dependent optical absorption induced by such a defect exhibits distinct features in the topological and trivial phases, offering an independent, experimentally accessible local indicator of the global topological order. Extending the platform to a multilayer geometry uncovers a nonsymmorphic projective symmetry that gives rise to Möbius band topology.

In this work, we develop a new framework for computing atom-resolved contributions to optical properties based on atoms-in-molecules (AIM) schemes. The formalism is independent of the specific AIM method and is made rigorous by partitioning momentum matrix elements into atomic contributions while exactly satisfying the relevant sum rules. Zincblende GaP provides a two-atom demonstration of the atom-resolved second-harmonic-generation (SHG) analysis using five AIM partitioning methods. The two-center Ga-P channels account for $80.6\%–82.2\%$ of the SHG response, despite the pronounced partition dependence of the atomic charges. We then apply the framework to six representative ultraviolet nonlinear-optical crystals: $\beta \text{−}{\text{BaB}}_2{\text{O}}_4$ (BBO), ${\text{LiB}}_3{\text{O}}_5$ (LBO), ${\text{CsB}}_3{\text{O}}_5$ (CBO), ${\text{CsLiB}}_6{\text{O}}_{10}$ (CLBO), ${\text{KBe}}_2{\text{BO}}_3{\text{F}}_2$ (KBBF), and ${\text{LiCs}}_2{\text{PO}}_4$ (LCPO). The atom-triplet decomposition shows that two-center channels dominate the principal SHG components, while on-site terms are smaller and multicenter terms provide an important secondary contribution. Although the AIM charges, detailed local percentages, and exact pathway ranks depend on the partition, the physical interpretation remains stable across the tested AIM methods. B/O-only pathways dominate the leading responses of KBBF and LBO. Mixed pathways involving B/O or P/O atoms and cations make substantial contributions to the leading responses of BBO, CBO, CLBO, and LCPO. The decomposition framework therefore establishes a quantitative connection between local response pathways and the bulk nonlinear-optical response.

Employing a semiclassical method based on analytic continuation, we compute the electron-hole pair production rate in biased bilayer graphene subject to an in-plane electric field. This approach, originally due to Zwaan, bypasses the need for exact solutions at turning points, which are generally unavailable beyond linear or quadratic band structures. Applying this technique to biased bilayer graphene reveals nonstandard features of the asymptotic wave functions, in particular, the necessity of retaining decaying components even in classically allowed regions. By providing a fully analytic solution, this work complements and clarifies earlier results based on hybrid analytical–numerical treatments, and importantly establishes the absolute normalization of the pair production rate, and hence, of the tunneling current.

Recently, a chromium-based kagome metal $\mathrm{CsC}{\mathrm{r}}_3\mathrm{S}{\mathrm{b}}_5$ has attracted significant attention due to the coexistence of density-wave-like (DW-like) orders and unconventional superconductivity; however, the nature of the DW-like orders remains elusive. Here, we perform a scanning tunneling microscopy and spectroscopy study on multiple $\mathrm{CsC}{\mathrm{r}}_3\mathrm{S}{\mathrm{b}}_5$ crystals and identify a robust $4\times \sqrt{3}$ charge order (CO) on the $\mathrm{S}{\mathrm{b}}_2$-terminated surface, alongside other region-dependent charge modulations. Through comparative analysis and structural simulations, we attribute the $4\times \sqrt{3}$ CO to the coherent superposition of the underlying Sb lattice, a $2\times \sqrt{3}$ charge stripe, and additional fine-structural distortions. Our density functional theory calculations on bulk $\mathrm{CsC}{\mathrm{r}}_3\mathrm{S}{\mathrm{b}}_5$ suggest that, among the considered spin density wave (SDW) configurations, a $2\times \sqrt{3}$ SDW has the lowest energy, which will induce a $2\times \sqrt{3}$ charge modulation. This provides a possible bulk-derived scenario for the $2\times \sqrt{3}$ CO component. The possible factors influencing the region-dependent charge modulations are also discussed. Our study provides a microscopic picture for the abundant COs in $\mathrm{CsC}{\mathrm{r}}_3\mathrm{S}{\mathrm{b}}_5$ and highlights the propensity of magnetic kagome metals to host multiple, nearly degenerate, and competing electronic orders.

Quantum annealing with the D-Wave Advantage system in the random Ising model on a cubic lattice is simulated using a three-dimensional tensor network. The Hamiltonian is driven across a quantum phase transition from a paramagnetic phase to a spin-glass phase. The network is represented as a tensor product state, also known, particularly in two dimensions, as a projected entangled-pair state. The annealing procedure is repeated for a range of annealing times in order to test the Kibble-Zurek (KZ) power law governing the residual energy at the end of the annealing ramp. For an infinite lattice with periodic nearest-neighbor random Ising couplings, the final energy is evaluated using a deterministic method. For a finite lattice with open boundaries, we introduce a more efficient Monte Carlo sampling approach. In both cases, the residual energy as a function of annealing time approaches the KZ power law as the annealing time increases.

The imaginary-time Mpemba effect (ITME) describes a counterintuitive relaxation scenario in which a higher-energy initial state approaches the ground state faster than a lower-energy one. While most studies focus on energy relaxation, whether this anomalous hierarchy persists across other observables remains largely unexplored. Here, using exact diagonalization and Gutzwiller mean-field theory, we systematically investigate the ITME in the one- and two-dimensional extended Bose-Hubbard model—and crucially, contrast energy relaxation with that of other physical quantities, including the superfluid order parameter, local density, and trace distance. Exact diagonalization reveals that the imaginary-time Mpemba effect is controlled by the initial state's spectral projection onto low-lying eigenstates. Mean-field calculations further show that the imaginary-time Mpemba effect occurs across distinct quantum phases, including superfluid and supersolid, indicating a degree of universality. Strikingly, the relaxation of energy is not always synchronized with that of other physical quantities: Energy curves may cross even when the superfluid order parameter does not and vice versa. To further clarify the self-consistent mean-field dynamics, we analyze both the nonlinear relaxation stage and the asymptotic regime near the target fixed point. In a representative ITME case, the initially higher-energy state exhibits a stronger second-instantaneous-excited-state contribution and a larger energy-decay rate, while the late-time relaxation near the target fixed point is governed by the amplitudes of the slow relaxation modes. The results connect spectral projection, self-consistent nonlinear evolution, and observable-dependent relaxation, offering a new perspective on anomalous relaxation in strongly correlated many-body systems.