Prethermal discrete time crystals (PDTCs), an emergent nonequilibrium phase of matter, have been studied in two- and higher-dimensional lattices with nearest-neighbor (NN) interactions and one-dimensional (1D) lattices with long-range interactions. However, different from prethermalization that can be observed in 1D Floquet classical spin systems with NN interactions, classical PDTCs in Floquet 1D systems with only NN interactions have not been proposed before. Here, we demonstrate the emergence of disorder-free discrete time crystals (DTCs) in 1D Floquet classical spin systems with NN interactions. We show that the thermalization time first grows exponentially as the driving frequency increases and is then saturated, which depends on the energy density of the initial state. Since thermalization of the effective Hamiltonian is slow, there is no typical prethermalization and PDTCs in the Floquet system before final thermalization. The robustness of DTC order is verified by introducing imperfect spin flip operations. Our work provides an exploration of quantum characteristics, when considering the classical counterparts of quantum phenomena, and will be helpful for further investigations of both classical and quantum prethermal systems and discrete time-crystalline order.

The engineering of magnetic anisotropy in two-dimensional (2D) materials is crucial for the development of high-density, low-power spintronic devices. Here, we propose an efficient strategy to achieve superior magnetic tunability by constructing an in-plane lateral heterostructure (LH-VSeTe) from Janus VSeTe monolayers. We demonstrate that this covalently bonded heterostructure is not only energetically favorable and dynamically stable but also exhibits robust intrinsic ferromagnetism. Our results show that both biaxial strain and hole doping can effectively control their magnetic anisotropy energy, inducing a spin reorientation from in-plane to perpendicular magnetic anisotropy by changing the spin-orbit coupling interactions of Te atoms. Most significantly, the LH-VSeTe structure exhibits a giant voltage-controlled magnetic anisotropy (VCMA) coefficient of approximately 481 fJ/Vm, which is over an order of magnitude larger than that of its 2H counterpart. This exceptional VCMA effect stems from the unique charge rearrangement and alternation of electronic occupations at the lateral interface under an electric field. Our work establishes in-plane heterostructuring as a powerful paradigm for designing 2D magnets with enhanced functionalities and identifies LH-VSeTe as a prime candidate for future spintronic applications.

Composite multiferroics consisting of a ferroelectric material interfaced with a ferromagnetic material can function above room temperature and exhibit improved magnetoelectric coupling compared to single-phase multiferroic materials, making them desirable for applications in energy-efficient electronic devices. In this study, we demonstrate electrical side-gate control of magnetoresistance and magnetic anisotropy in single-crystalline ferromagnetic ${\mathrm{Fe}}_{0.75}{\mathrm{Co}}_{0.25}$ thin films grown on ferroelectric PMN-PT (001) substrates by molecular beam epitaxy. ${\mathrm{Fe}}_{0.75}{\mathrm{Co}}_{0.25}$ is selected due to its large magnetoelastic coupling and low magnetic damping. We find that the magnetoresistance curves of patterned ${\mathrm{Fe}}_{0.75}{\mathrm{Co}}_{0.25}$ films are controlled by voltages applied to electrostatic side gates. Angle-dependent magnetoresistance scans reveal that the origin of this effect is strain-mediated variation of the magnetic anisotropy due to piezoelectric effects in the PMN-PT. This electrical control of magnetic properties could serve as a building block for future magnetoelectronic and magnonic devices.

The coupling between strain and magnetic order arises due to the modifications in orbital overlap and crystal field symmetry, giving rise to strain-induced magnetic anisotropy. Here, we find an evolution of strain-tuned out-of-plane magnetic anisotropy in thin films of double perovskite ${\mathrm{Sm}}_2{\mathrm{CoFeO}}_6$, which possesses room-temperature ferromagnetism. Notably, the magnetization of the thin films is enhanced nearly 40 times compared to its bulk value, making a strong case for strain-induced ferromagnetism. The intrinsic magnetic anisotropy constant increases from 3 ${\mathrm{kJ}/\mathrm{m}}^3$ to 120 ${\mathrm{kJ}/\mathrm{m}}^3$ with the application of tensile strain from 0.7% to 2%. The magnetostriction coefficient is estimated to be as large as $30\times {10}^{-6}$. The strain-induced ferromagnetism in ${\mathrm{Sm}}_2{\mathrm{CoFeO}}_6$ is well supported with density functional theory calculations. Such magnetoelastic coupling-driven magnetic anisotropy tuning is further discussed in the micromagnetic framework.

The nonreciprocal propagation of spin waves (SWs) offers opportunities for developing novel functional magnonic logic devices, where controllability is crucial for magnetic-signal processing. Domain walls act as natural waveguides due to their magnetic configuration, offering a platform for the in-depth investigation of nonreciprocal SW propagation and its manipulation. In this work, we theoretically and numerically investigate the tunable SW nonreciprocity in ferrimagnetic domain-wall channels under the influence of external field. It is revealed that the Dzyaloshinskii-Moriya interaction exerts dual control over both nonreciprocal SW propagation and spin-splitting phenomena. Moreover, SW nonreciprocity is magnetically tunable, with its sign reversibly switched by inverting the applied field direction, while preserving the host-spin configuration. The orientation of the magnetic field can selectively modify the domain wall structure, offering precise control over SW nonreciprocity. Ultimately, we demonstrate a controllable SW transmission scheme via external magnetic-field modulation, providing critical insights for the design of future magnonic devices.

Tuning magnetic anisotropy through chemical doping is a powerful strategy for designing functional ma terials with enhanced magnetic properties. Here, we report an enhanced ${\mathrm{Er}}^{3+}$ magnetic moment resulting from nonmagnetic ${\mathrm{Lu}}^{3+}$ substitution in the honeycomb-lattice antiferromagnet ErOCl. Unlike the Curie-Weiss type divergence typically observed in diluted magnetic systems, our findings reveal a distinct enhancement of magnetization per ${\mathrm{Er}}^{3+}$ ion under high magnetic fields, suggesting an unconventional mechanism. Structural analysis reveals that ${\mathrm{Lu}}^{3+}$ doping leads to a pronounced contraction of the $c$ axis, which is attributed to chemical pressure effects, while preserving the layered SmSI-type crystal structure with space group $R\overline{3}m$. High-resolution Raman spectroscopy reveals a systematic blueshift of the first and seventh crystalline electric field (CEF) excitations, indicating an increase in the axial CEF parameter $B_2^0$. This modification enhances the magnetic anisotropy along the $c$ axis, leading to a significant increase in magnetization at low temperatures and under high magnetic fields, contrary to conventional expectations for magnetic dilution. Our work not only clarifies the intimate connection between magnetism and CEF in rare-earth compounds, but more importantly, it reveals a physical pathway to effectively tune magnetic anisotropy via anisotropic lattice distortion induced by chemical pressure.

Topological superconductors host gapless surface states that fundamentally alter their electromagnetic response through the axion field term $\theta \mathit{E}·\mathit{B}$, arising from the topological magnetoelectric effect. In this work, we investigate the electromagnetic properties of a three-dimensional topological Weyl superconductor by leveraging its theoretical mapping to a four-dimensional topological insulator with $s$-wave superconducting boundaries. By incorporating the tilt of Weyl cones into this model, we demonstrate that the tilt vector $\mathit{\zeta }$ anisotropically modifies the axion field profile near the surface, leading to a tilt-enhanced Meissner effect and anomalous magnetic penetration depths. We show that the magnetic field component perpendicular to the tilt direction exhibits a non-exponential, hypergeometric decay dictated by the interplay between the axion term and $\mathit{\zeta }$, while the parallel component remains largely tilt-insensitive—a hallmark of axion-mediated anisotropy absent in trivial superconductors. Remarkably, all tilt-dependent electromagnetic responses follow a universal scaling law, revealing a fundamental symmetry in the system's behavior. Furthermore, we predict a tilt-dependent planar Hall current at the surface, directly tied to the topological surface states.

We study the effect of noise on the dynamics of the transverse-field Ising model quenched across a quantum critical point. To quantify two-spin correlations, we employ the quantum Fisher information (QFI) and the Wigner-Yanase skew information (WYSI) as measures of quantum coherence. In the noiseless case, in contrast to the dynamics of entanglement in anisotropic XY chains, both QFI and WYSI increase monotonically with the ramp quench time, approaching their adiabatic limits without exhibiting any Kibble-Zurek-type scaling with quench duration. In contrast, when noise is added to the quench protocol, the coherence dynamics change qualitatively: QFI and WYSI both decay exponentially with the timescale of a ramp quench, with an exponent determined by the noise intensity. Furthermore, the maximum ramp time, at which either of these measures reaches its maximum, scales linearly with the noise variance, featuring the same exponent that determines the optimal annealing time for minimizing defect production in noisy quantum annealing.

Thouless pumping manifests as a quantized transport phenomenon in time-driven Hermitian systems, protected by topological invariants. Non-Hermitian physics, arising in open systems, significantly affects the topological properties of quantum systems, giving rise to an intriguing interplay between topology and non-Hermiticity. We study Thouless pumping in generic non-Hermitian systems using the tight-binding formalism, and demonstrate that the transport dynamics of topological pumping are qualitatively distinct from those in Hermitian systems. Specifically, the Thouless pumping is governed by the interplay between the complex Berry curvature and the complex energy spectrum, deviating from the conventional quantized Chern number. Notably, we found that the deviation can be eliminated when system's average imaginary spectrum vanishes, restoring the charge pumping to Chern number in non-Hermitian systems. We validate our analytical findings through concrete examples. Our work provides new insights into transport phenomena in non-Hermitian experimental setups, such as lossy on-chip photonic systems.

Understanding the mechanism driving magnetization switching in spin-orbit-torque-assisted devices remains a subject of debate. While originally attributed to the spin Hall effect and spin Rashba-Edelstein effect, recent discoveries related to orbital moments induced by the orbital Hall effect and the orbital Rashba-Edelstein effect have added complexity to the comprehension of the switching process in nonmagnet/ferromagnet bilayers. Addressing this challenge, we present a quantitative investigation of a Pt/Co bilayer by employing atomistic spin dynamics simulations, incorporating the proximity-induced moments of Pt, as well as electrically induced spin and orbital moments obtained from first-principles calculations. Our layer-resolved model elucidates the dampinglike and fieldlike nature of the induced moments by separating them according to their even and odd magnetization dependence. In addition to demonstrating that a larger fieldlike spin-orbit-torque contribution comes from previously disregarded induced orbital moments, our work highlights the necessity of considering interactions with Pt-induced moments at the interface, as they contribute significantly to the switching dynamics.

Angle-resolved photoemission spectroscopy is the leading tool for studying the symmetry and structure of the order parameter in superconductors. The recent improvement of the technique made it possible to detect the superconducting energy gap at the surface of topological t-${\mathrm{PtBi}}_2$ via observation of the record-breaking narrow line shapes. The promising new physics uncovered requires further investigation of the spectral and gap functions of t-${\mathrm{PtBi}}_2$, but the challenging experimental conditions severely limit the application of conventional ARPES setups. In this work, we use synchrotron-based measurements and show that the gap at the surface Fermi arc in t-${\mathrm{PtBi}}_2$ can be detected even with more relaxed experimental conditions than in our previous laser-based studies. At the same time, using simple model of ARPES spectra, we identify the minimum requirements to detect the gap and consider cases where the gap cannot be resolved.

We present a comprehensive set of numerically exact results for the Anderson model of a quantum dot coupled to two electrodes in a nonequilibrium regime. We use a high order perturbative expansion in power of the interaction $U$, coupled to a cross-extrapolation method to long time and large interaction. The perturbative series is computed up to 20–25 orders using tensor cross-interpolation. We calculate the full Coulomb diamond bias voltage–gate voltage map, including its Kondo ridge, that forms the standard experimental signature of the Coulomb blockage and the Kondo effect. We present current-voltage characteristics that spans three orders of magnitude in bias voltage, and we display five different regimes of interest, from probing the Kondo resonance at small bias to saturation at very high bias. Our technique also naturally produces time-resolved interaction quenches, which we use to study the dynamics of the formation of the Kondo cloud. Finally, we predict several qualitatively new physical features that should be within reach of existing or upcoming experiments.

We study the Gross-Neveu-Yukawa field theory for the $\mathrm{SO}(N$) symmetric traceless rank-2 tensor order parameter coupled to Majorana fermions using the $\epsilon$-expansion around upper critical dimensions of $3+1$ to two loops. Previously we established in the one-loop calculation that the theory does not exhibit a critical fixed point for $N\ge 4$, but that nevertheless the stable fixed point inevitably emerges at a large number $N_f$ of fermion flavors. For $N_f<N_{f,c1}\approx N/2$, no critical fixed point exists; for $N_{f,c1}<N_f<N_{f,c2}$, a real critical fixed point emerges from the complex plane but fails to satisfy the additional stability conditions necessary for a continuous phase transition; and finally only for $N_f>N_{f,c2}\approx N$ does the fixed point satisfy the stability conditions as well. In the present work we compute the $O\left(\epsilon \right)$ (two-loop) corrections to the critical flavor numbers $N_{f,c1}$ and $N_{f,c2}$. Most importantly, we observe a sharp decrease in $N_{f,c2}$ from its one-loop value, which brings it closer to the point $N_f=1$ relevant to the standard Gross-Neveu model. Some three-loop results are also presented and discussed.

The ground state of second-quantized quantum chemistry Hamiltonians is key to determining molecular properties. Neural quantum states (NQSs) offer flexible and expressive wave-function Ansätze for this task but face two main challenges: highly peaked ground-state wave functions hinder efficient sampling, and local energy evaluations scale quartically with system size, incurring significant computational costs. In this work, we overcome these challenges by introducing a suite of algorithmic enhancements, which includes efficient periodic compact subspace construction, truncated local energy evaluations, improved stochastic sampling, and physics-informed modifications. Applying these techniques to the neural network backflow Ansatz, we demonstrate significant gains in both accuracy and scalability. Our enhanced method surpasses traditional quantum chemistry methods like coupled cluster singles and doubles (CCSD) and CCSD and perturbative triples [CCSD(T)], outperforms other NQS approaches, and achieves competitive energies with state-of-the-art ab initio techniques such as heat-bath configuration interaction, adaptive sampling configuration interaction, full configuration interaction quantum Monte Carlo, and density matrix renormalization group. A series of ablation and comparative studies quantifies the contribution of each enhancement to the observed improvements in accuracy and efficiency. Furthermore, we investigate the representational capacity of the Ansatz, finding that its performance correlates with the inverse participation ratio, with more delocalized states being more challenging to approximate.

We find an efficient approach to approximately convert matrix product states (MPSs) into restricted Boltzmann machine wave functions consisting of a multinomial hidden unit through a canonical polyadic (CP) decomposition of the MPSs. This method allows us to generate well-behaved initial neural network quantum states for quantum many-body ground-state calculations in polynomial time of the number of variational parameters and systematically shorten the distance between the initial states and the ground states while increasing the rank of the CP decomposition. We demonstrate the efficiency of our method by taking the transverse-field Ising model as an example and discuss possible applications of our method to more general quantum many-body systems in which the ground-state wave functions possess complex nodal structures.

A two-dimensional electron gas (2DEG) forms at the interface of complex oxides like $\mathrm{SrTi}{\mathrm{O}}_3$ (STO) and $\mathrm{LaTi}{\mathrm{O}}_3$ (LTO), despite each material having a low native conductivity, as a band and a Mott insulator, respectively. The interface 2DEG hosts charge carriers with moderate charge carrier density and mobility that raised interest as a material system for applications like field-effect transistors or detectors. Of particular interest is the integration of these oxide systems in silicon technology. To this end we study the carrier dynamics in a STO/LTO/STO heterostructure epitaxially grown on Si(001) both experimentally and theoretically. Linear THz spectroscopy was performed to analyze the temperature dependent charge carrier density and mobility, which was found to be in the range of ${10}^{12}\mathrm{c}{\mathrm{m}}^{-2}$ and 1000 $\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$, respectively. Pump-probe measurements revealed a very minor optical nonlinearity caused by hot carriers with a relaxation time of several 10 ps, even at low temperature. Density functional theory calculations with a Hubbard $U$ term on ultrathin STO-capped LTO films on STO/Si(001) show an effective mass of 0.64–0.68 $m_e$.

The injection and shift currents are generalized to the $\ell \mathrm{th}$-order injection and shift currents for the longitudinal conductivities in the two-band model, where $\ell$ is the power of the applied electric field. In addition, the formulas for the higher-order injection current are expressed in terms of the quantum metric, and those for the higher-order shift current are expressed in terms of the higher-order quantum connection. Then, they are applied to $p$-wave magnets, which are well described by the two-band Hamiltonian as far as low-energy physics is concerned. It is shown that the injection and shift currents are zero. On the other hand, the $\ell \mathrm{th}$-order injection and shift currents with odd $\ell$ are nonzero when the direction of the spin-splitting vector of the $p$-wave magnet points to an in-plane direction.

The stripping of two-dimensional (2D) perovskite thin films with thickness of only several atomic layers from 3D perovskite materials has been reported experimentally recently, which makes it possible to fabricate 2D perovskite ferroelectric tunnel junctions (FTJs). Motivated by this and based on density functional calculations, we design the 2D ${\mathrm{SrRuO}}_3/{\mathrm{BaTiO}}_3/{\mathrm{LaAlO}}_3/{\mathrm{SrRuO}}_3$ FTJ as a prototype to explore the performance of 2D perovskite FTJs relative to the 3D counterpart. The bistable states of the 2D FTJ are obtained as ferroelectric and antiferroelectric (AFE) states, which are different from those of the traditional 3D-perovskite FTJs, which usually have only uniform left polarization state and right polarization state. Importantly, first-principles calculations demonstrate that the switching between these two states results in the TER ratio as high as $4.570\times {10}^5\%$, which is nearly two orders of magnitude larger than that ($9.656\times {10}^3\%$) of the 3D counterpart. Further analysis indicates that it arises from the unusual higher transmission due to the interlayer resonant tunneling between the top and bottom layers in the antiferroelectric state in the 2D case as compared with the uniform polarization states. Consequently, when the perovskite FTJs are thinned down to the thickness of only several atomic layers, new states (AFE state in this device) may appear and thus strengthen the TER performance, providing new routes for designing perovskite-type FTJs and decreasing the device sizes.

We introduce a boundary condition twisted by time translation as a novel probe to characterize dynamical phases in periodically driven (Floquet) quantum systems. Inspired by twisted boundary conditions in equilibrium systems, this approach modifies the temporal evolution of the system upon completing a spatial loop, enabling the identification of distinct Floquet phases, including discrete time crystals (DTCs). By studying the spectral form factor (SFF) and its response to the twist, we uncover signatures of time-crystalline order, which exhibits periodic dependence on the twist parameter analogous to the Little-Parks effect in superconductors. We apply this framework to the kicked Ising model, demonstrating that our twist can distinguish time-crystalline phases.