We report on a study of the interplay between the supercurrent and spin-polarization in a two-dimensional superconducting system in the presence of a $d$-wave symmetric antiferromagnetic exchange interaction (altermagnetism). It is demonstrated that the supercurrent exhibits a transverse contribution in the presence of both constant and momentum-dependent exchange interactions. We also discuss the analog of the Edelstein effect for such material, showing that the induced spin polarization is quadratic in the supercurrent and $d$-wave symmetric.

The polynomial machine learning potentials (MLPs) described by polynomial rotational invariants have been systematically developed for various systems and used in diverse applications in crystalline states. In this study, we systematically investigate the predictive power of the polynomial MLPs for liquid structural properties in 22 elemental systems with diverse chemical bonding properties, including those showing anomalous melting behavior, such as Si, Ge, and Bi. We compare liquid structural properties obtained from molecular dynamics simulations using the density functional theory (DFT) calculation, the polynomial MLPs, and other interatomic potentials in the literature. The current results demonstrate that the polynomial MLPs consistently exhibit high predictive power for liquid structural properties with the same accuracy as that of typical DFT calculations.

Spin squeezing in systems with single-particle control is a well-established resource of modern quantum technology. Applied in an optical lattice clock it can reduce the statistical uncertainty of spectroscopic measurements. Here, we consider dynamic generation of spin squeezing with ultra-cold bosonic atoms with two internal states loaded into an optical lattice in the strongly interacting regime as realized with state-of-the-art experiments using a quantum gas microscope. We show that anisotropic interactions and inhomogeneous magnetic fields generate scalable spin squeezing if their magnitudes are sufficiently small, but not negligible. The effect of nonuniform filling caused by hole doping, nonzero temperature, and external confinement is studied at a microscopic level demonstrating their limiting role in the dynamics and scaling of spin squeezing.

We investigate imaginary gap-closed (IGC) points and their associated dynamics in dissipative systems. In a general non-Hermitian model, we derive the equation governing the IGC points of the energy spectrum, establishing that these points are only determined by the Hermitian part of the Hamiltonian. Focusing on a class of one-dimensional dissipative chains, we explore quantum walks across different scenarios and various parameters, showing that IGC points induce a power-law decay scaling in bulk loss probability and trigger a boundary phenomenon referred to as “edge burst.” This observation underscores the crucial role of IGC points under periodic boundary conditions (PBCs) in shaping quantum walk dynamics. Finally, we demonstrate that the damping matrices of these dissipative chains under PBCs possess Liouvillian gapless points, implying an algebraic convergence towards the steady state in long-time dynamics.

Manganese telluride (MnTe) is a prospective platform for ultrafast carrier dynamics, spin-based thermoelectrics, and magnon-drag transport due to its unique electronic and magnetic properties. We use inelastic neutron scattering to study both pure and lithium-doped MnTe, focusing on the influence of doping in opening a magnon gap. We use neutron powder diffraction to determine critical exponents for the phase transition in both pure and Li-doped MnTe and complement this information with muon spin rotation/relaxation. The opening of the magnon gap and spin reorientation in Li-doped MnTe is mainly due to increased magnetic anisotropy along the [001] axis, a feature not present in pure MnTe.

Recent experiments on cuprates have shown the possibility of opening a gap above the superconducting critical temperature, in the so-called phase-fluctuating state, by enhancing the phase coherence of preformed Cooper pairs. Quench-drive spectroscopy, an implementation of 2D coherent spectroscopy, has emerged as a powerful tool for investigating out-of-equilibrium superconductors and their collective modes. In this paper, we enrich the quench-drive scheme by developing a systematic generalization to study the nonlinear response of $d$-wave incoherent Cooper pairs in a symmetry-resolved manner. In particular, we not only show that it is possible to obtain a third-harmonic signal from fully incoherent pairs with an equilibrium vanishing order parameter, but we also characterize the full flourishing 2D spectrum of the generated nonlinear response. The results provide a deeper theoretical insight on recent experimental results, opening the door to a symmetry-driven design of future experiments on unconventional and enhanced superconductors.

In a recent paper [Shang et al., Phys. Rev. B 107, 224504 (2023)], the authors study the physical properties of TaReSi compounds having $Ima2$ structure. This noncentrosymmetric structure is proposed to be the source of topological properties for the mentioned compound. However, for a correct description of topological features, it is important to recognize the correct structure of the compound at low temperatures. In this Comment, we show that $Ima2$ cannot be realized by TaReSi and is unstable at low temperature. The $Ima2$ structure contains the soft modes at the S (1/2, 0, 0) point, which leads to the stable structure with $Cm$ symmetry. Notably, the stable $Cm$ system also has a noncentrosymmetric structure, which can be the actual source of topological properties.

This work presents the structural phase percolation during the entire temperature range of metallic-to-insulating phase transition (MIT) in a high quality $\mathrm{NdNi}{\mathrm{O}}_3$ thin film deposited onto (001)-oriented $\mathrm{LaAl}{\mathrm{O}}_3$ substrate. The results show the correlation between the symmetry breaking oxygen-breathing distortion and the occurrence of the MIT. From Raman scattering experiments, the monoclinic and orthorhombic phases’ coexistence was fully characterized, and their volume fractions determined as a function of temperature. At the critical threshold of the insulating domain percolation, the monoclinic volume fraction attains the predicted 2/3 for a three-dimensional lattice, evidencing a structural percolative process. The experimental results here reported give a more general insight into percolative phenomena in $\mathrm{NdNi}{\mathrm{O}}_3$ thin films.

$\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ solid solutions not only play a crucial role in carbon storage and transport within the deep mantle, but also serve as a great case for studying the spin transition behavior of $\mathrm{F}{\mathrm{e}}^{2+}$ in the fairly isometric sixfold coordinated octahedral sites. However, simultaneously high temperature and pressure measurements on the spin crossover of $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ remain scarce, which greatly limits our knowledge about the pressure-induced spin transition of $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ under extreme conditions. In this study, we investigated three representative synthesized $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ samples at high temperatures and pressures up to 65 GPa and 900 K using Raman spectroscopy coupled with diamond-anvil cells using neon (Ne) as a pressure-transmitting medium. Interestingly, $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ exhibits abnormal vibrational properties and spin phase diagrams at high temperatures and pressures. The onset of spin crossover for the three $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ samples decreases with increasing temperatures from 300 to 500 K, followed by an inverse increase at higher temperatures. Moreover, the width of spin crossover is $\sim 7\text{−}9$ GPa at 800 K, compared to 3–4 GPa at 300 K. Notably, iron-rich $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$ displays a narrower width of spin crossover than its iron-poor counterpart. These findings provide insights into the effects of temperature and iron concentration on the pressure-induced spin transition of $\left(\mathrm{Mg},\mathrm{Fe}\right)\mathrm{C}{\mathrm{O}}_3$.

How a closed system thermalizes, especially in the absence of global conservation laws but in the presence of disorder and interactions, is one of the central questions in nonequilibrium statistical mechanics. We explore this for a disordered, periodically driven Ising chain. Our numerical results reveal inhomogeneous thermalization leading to a distribution of thermalization timescales within a single disordered sample, which we encode via a distribution of effective local temperatures. Using this, we find an excellent collapse without any fitting parameters of the local relaxation dynamics for the entire range of disorder values in the ergodic regime when adapting the disorder-averaged diagonal entanglement entropy as internal “time” of the system. This approach evidences a remarkably uniform parametrization of the dynamical many-body evolution of local temperature within the otherwise highly heterogeneous ergodic regime, independent of the strength of the disorder.

We show that, in solids with Jahn-Teller effect (JTE) or pseudo-JTE (PJTE) centers, local dipolar displacements may occur, which are almost freely rotating in external electric fields (like in polar liquids), thus realizing solid-state orientational polarizability predicted by Debye [Phys. Z. 13, 97 (1912)]. As illustrative examples, we consider impurity ions in noncentrosymmetric cubic crystals with a degenerate ground state coupled to polar modes of nearest neighboring ligands via the JTE and local centers in centrosymmetric crystals with electronic pseudodegeneracy realizing the PJTE. In the JTE $T$ ⊗ $t_2$ problem in a tetrahedral site, the vibronic coupling to trigonal modes creates off-center shifted dipolar distortions of the dopant along one of the four equivalent minima of the adiabatic potential energy surface. Resonating between these wells by tunneling or over-the-barrier transitions, the dipoles perform hindered rotations in space, like molecular dipoles in polar liquids and gases. In external electric fields, the local dipolar minima become nonequivalent with the dipolar distortion trapped in the specific well, which is lowered by the applied field in the same direction in all the centers, thus realizing the solid-state orientational polarizability. Distinguished from the JTE case, the PJTE may produce off-center shifted dipolar distortions in both centrosymmetric and noncentrosymmetric sites, with the disordered local dipolar distortions resonating between the equivalent wells at each PJTE site. Under the applied electric field, the system becomes trapped in the lower well along the field. According to numeric estimates, the orientational contribution to polarizability is by orders of magnitude larger than the one from the displacive shifts of the charged units, quite similar to the orientational polarizability of polar liquids and gases.

Proximitized topological insulators (PTIs) have received significant research attention over the past two decades. In this paper, we demonstrate that a low-dimensional PTI in the topologically nontrivial phase (TP) exhibits interference-induced surface superconductivity (SSC) at the system ends/edges with the critical temperature $T_{cs}$ significantly higher than $T_{cb}$ deep inside the system (low-dimensional bulk). Such an SSC is built due to the interference of the scattering quasiparticle states, rather than the presence of the topological bound states (TBSs). As the system delves deeper into the TP, a nontrivial competition between the scattering quasiparticles and TBSs at the surface leads to a crossover from the interference- to TBS-induced phase, where the SSC is governed by the TBSs. Our paper unveils a substantial variation in the maximal $T_{cs}$ along this crossover, attaining values being twice the maximal $T_{cb}$ of the PTI. Beyond shedding light on the nature of the SSC in PTIs, our paper introduces a tangible method for experimentally manipulating their critical superconducting temperatures.

A comprehensive study of the vortex phases and vortex dynamics is presented for a recently discovered high-temperature superconductor ${\mathrm{ThH}}_{10}$ with $T_{\mathrm{C}}=153\mathrm{K}$ at 170 GPa. The obtained results strongly suggest a quasi-two-dimensional (2D) character of the vortex-glass phase transition in ${\mathrm{ThH}}_{10}$. The activation energy yields a logarithmic dependence $U_0\propto ln\left(H\right)$ on magnetic field in a low-field region and a power-law dependence $U_0\sim H^{-1}$ in a high-field region, signaling a crossover from 2D regime to three-dimensional collective pinning regime, respectively. Additionally, a pinning force-field dependence showcases dominance of surface-type pinning in the vicinity of $T_{\mathrm{C}}$. Thermal activation energy $\left(U_0\right)$, derived within thermally activated flux-flow theory, takes very high values above $2\times {10}^5\mathrm{K}$ together with the Ginzburg number $Gi=0.039–0.085$, which is lower only than those of BiSrCaCuO cuprates and 10–3–8 family of iron-based superconductor. This indicates the enormous role of thermal fluctuations in the dynamics of the vortex lattice of superhydrides, the physics of which is similar to the physics of iron-based and copper-based high-temperature superconductors.

Topological superconductors have attracted tremendous interest in recent years because of their fundamental importance and potential applications in topological quantum computing. Here, using a monolayered Pb(111) film grown on a $\mathrm{NbS}{\mathrm{e}}_2$ substrate as an example, we show that it is possible to render a hybrid superconducting system nontrivial topology by combining two conventional $s$-wave superconductors with sufficiently strong spin-orbit coupling (SOC). We first demonstrate, based on first-principles calculations, that the monolayered Pb(111) film is stable on $\mathrm{NbS}{\mathrm{e}}_2$, and the system possesses a nonzero $Z_2$ topological invariant as well as Dirac-like edge states. Such a nontrivial topology originates from hybridization of the Pb and $\mathrm{NbS}{\mathrm{e}}_2$ bands, associated with a gap closure and reopening process in the presence of SOC. We further reveal that the ($3\times 3$)-type charge density wave (CDW) on the $\mathrm{NbS}{\mathrm{e}}_2$ surface is converted into a ($2\times 2$)-type CDW for the heterosystem, and the nontrivial topology is inherited in the CDW phase. Moreover, the CDW phase is still superconducting, albeit with a reduced transition temperature, exhibiting delicate competitions between the CDW and superconducting orders. Our findings offer opportunities for realizing topological superconductivity based on conventional $s$-wave superconductors.

Nodal chain semimetals protected by nonsymmorphic symmetries are distinct from Dirac and Weyl semimetals, featuring unconventional topological surface states and resulting in anomalous magnetotransport properties. Here, we reveal that ferromagnetic $\mathrm{FeI}{\mathrm{n}}_2{\mathrm{S}}_4$ is a suitable nodal chain candidate in theory. Centrosymmetric $\mathrm{FeI}{\mathrm{n}}_2{\mathrm{S}}_4$ with nonsymmorphic symmetries shows half metallicity and clean band crossings with hourglass-type dispersion tracing out nodal lines. Owing to glide mirror symmetries, the nontrivial nodal loops form a nodal chain, which is associated with the perpendicular glide mirror planes. These nodal chains are robust against spin-orbital interaction, giving rise to the coexistence of drumhead-type surface states and closed surface Fermi arcs. Moreover, the nodal loops protected by nonsymmorphic symmetry contribute to large anomalous Hall conductivity and the anomalous Nernst conductivity. Our results provide a platform to explore the intriguing topological state and transverse transport properties in a magnetic system.

The shape of the Fermi surface, and the cyclotron effective mass of the kagome magnet $\mathrm{Gd}{\mathrm{V}}_6\mathrm{S}{\mathrm{n}}_6$ charge carriers are investigated using de Haas–van Alphen (dHvA) oscillation measurements and electronic band structure calculations. The temperature- and angle-dependent torque magnetometry measurements revealed at least nine different frequencies ranging from $\sim 10$ T up to $\sim 9000$ T. These frequencies correspond to extremal areas of the Fermi surface ranging from $\sim 0.2\%$ up to 50% of the first Brillouin zone, qualitatively consistent with the electronic band structure calculations. The angle-dependent dHvA oscillation frequencies indicate that the smaller pockets of the Fermi surface have an almost three-dimensional character whereas the bigger pockets of the Fermi surface are mostly two dimensional. We also find evidence of the presence of light $\left[0.28\left(1\right)m_0\right]$ as well as heavy $\left[2.37\left(18\right)m_0\right]$ charge carriers through the analysis of the temperature dependence of dominant frequencies. The comparison of the observed frequencies with the electronic band structure calculations indicates that the heavy masses correspond to saddle-point-like features of electronic band structure at the $M$ point. The observation of the multiple low frequencies and the calculated contributions from various bands to such low frequencies prevent the estimation of the topological nature of bands containing lighter fermions. In conclusion, our work reveals the features of a Fermi surface containing enhanced mass fermions originating from saddle points in the electronic band structure at the $M$ point, which is inherent to kagome lattices.

We construct an effective field theory for an interacting Fermi liquid with nonzero Berry curvature at zero temperature, called the Berry Fermi liquid. We start with the extended phase space formalism, incorporating physical time into the configuration space. This approach allows us to include the time dependence of the background gauge fields “covariantly” into the symplectic structure. Upon restricting to the physical hypersurface, the effective action that lives on the coadjoint orbit becomes the minus free energy on the extended phase space. We also derive the action perturbatively in external fields using the canonical variables. For applications, we compute both linear and nonlinear electrical responses using the Kubo formula and identify contributions from the electric and magnetic dipole moments, which stem from interactions breaking parity and time-reversal symmetry. The anomalous Hall effect is confirmed using the kinetic theory.

We present an experimental and theoretical study of the lowest exciton states in a 30-nm single GaAs quantum-well heterostructure in different electric fields. We found that the excitons in quantum wells are highly sensitive to an electric field and demonstrate nonlinear behavior in terms of their energy position, amplitude, spectral width, and phase of exciton resonances in reflection spectra. Comparison of experimental results with theoretical calculations allowed us to reliably determine the electric field strength in the quantum-well layer.

The recent experimental discovery of the zero-field fractional Chern insulator (FCI) in twisted ${\mathrm{MoTe}}_2$ moiré superlattices has sparked immense interest in this exotic topological quantum state. The FCI has also been observed in previous experiments in magic angle twisted bilayer graphene (TBG) under a finite magnetic field of about 5 Tesla. Generally, the stabilization of FCI requires fine-tuning the topological band to satisfy certain conditions. It would still be helpful to have an intuitive picture to understand the different behaviors in twisted ${\mathrm{MoTe}}_2$ and TBG. Here, we compare them through the lens of emergent gauge fields. In TBG, the system can be mapped to two Dirac fermions coupled to emergent gauge fields with opposite signs. In contrast, the twisted ${\mathrm{MoTe}}_2$ reduces to a hole with parabolic dispersion coupled to an emergent gauge field. Although the stabilization of FCI generally requires fine-tuning of the band dispersion and its quantum geometry, this contrasting gauge structure provides another perspective on the observed difference: the zero-field FCI is stable in ${\mathrm{MoTe}}_2$ but absent in TBG. Based on this understanding, we will explore potential strategies for stabilizing FCI in both moiré superlattices.