Solid-state ionic conductors are pivotal for advancing energy storage technologies, yet their performance is critically governed by mesoscale structural features that influence ionic percolation pathways. In this work, random resistance model is employed to unravel the effects of mesoscopic features, including the size, shape, and alignment of grains and pores, on ionic transport percolation networks in polycrystalline ionic conductors. Our simulations reveal that larger grain sizes and vertically aligned columnar grains significantly enhance ionic conductivity by reducing percolation thresholds. Notably, vertically aligned pores further optimize percolation networks, enabling conductivity exceeding that of fully dense materials in specific configurations. By correlating simulated results with experimental data for garnet-type lithium-ion and oxygen-ion conductors, we demonstrate the model's robustness in predicting structure-property relationships. These insights establish a universal framework for designing high-performance solid electrolytes through mesoscale engineering, with broad implications for batteries, fuel cells, and beyond.

We report magnetization measurements under hydrostatic pressure up to approximately 1.6 GPa in the spin-1 quasi-one-dimensional frustrated antiferromagnets ${\mathrm{CsNiCl}}_3, {\mathrm{RbNiCl}}_3$, and ${\mathrm{CsNiBr}}_3$. Magnetic susceptibilities observed at various pressures are almost completely accounted for by combining the theoretical susceptibility for the spin-1 antiferromagnetic Heisenberg chain, calculated using the quantum Monte Carlo method, with the mean field arising from two interchain exchange interactions, which are an order of magnitude larger than the single interchain exchange interaction used in the conventional model. The antiferromagnetic intrachain $J_0$ exchange interaction increases significantly with pressure in all three. The single-ion anisotropy $D$ of the easy-axis type increases significantly with pressure in ${\mathrm{CsNiCl}}_3$ and ${\mathrm{RbNiCl}}_3$ while not in ${\mathrm{CsNiBr}}_3$. This significant change in magnetic interactions leads to large shifts in phase boundaries. One-dimensionality increases with increasing pressure in ${\mathrm{CsNiCl}}_3$ but not in ${\mathrm{RbNiCl}}_3$ and ${\mathrm{CsNiBr}}_3$.

We present a comparative study of vortex-glass (VG) phase, vortex pinning, and vortex dynamics in superconducting niobium-rhenium (NbRe) films and NbRe/permalloy bilayers fabricated by the dc magnetron sputtering technique, where permalloy (Py) serves as the ferromagnetic layer. Current-voltage characteristics were measured as a function of temperature and magnetic field to investigate the VG transition, analyzed through scaling laws to determine the VG phase line, $H_g\left(T\right)$. NbRe films exhibit systematically higher $H_g\left(T\right)$ magnitude than the NbRe/Py bilayers, indicating stronger vortex pinning in the former. The reduced $H_g\left(T\right)$ trend observed in the NbRe/Py bilayers is attributed to the superconducting proximity effect and the homogeneous magnetic exchange interaction at the NbRe/Py interface. To further elucidate the pinning properties, critical current densities and pinning forces were evaluated, revealing that vortex pinning is strongly influenced by structural inhomogeneities and disorder in both systems, with consistently larger pinning forces in NbRe films. The weaker pinning in NbRe/Py bilayers is reflected in their vortex-instability behavior, characterized significantly by their higher vortex velocities compared to NbRe films.

We predict that the spin-polarized electrons in a two-dimensional triangular lattice with strong electron-electron repulsion give rise to $f$-wave pairing. The key point is that the first-order interaction, which is usually pair breaking, vanishes or nearly vanishes in certain $f$-wave channels due to symmetry constraints. As a result, these $f$-wave pairing channels are governed by the subleading-order processes which enable pairing when the perturbation theory is controlled. We illustrate this point using the Hubbard model on the triangular lattice with on-site and nearest-neighbor repulsion, where we find a transition temperature $T_c\sim 0.2\%$ of the Fermi energy. For a general screened interaction, the same idea works asymptotically, but a third-order calculation is needed to fully determine the strength of $f$-wave pairing.

Recently, it was predicted that nonreciprocal magnetoelectric effect in antiferromagnetic multilayered metamaterials occurs in two distinct versions. One is the conventional axion response, while another one is dual axion response captured by electrodynamics with magnetic charge. Here we investigate a model condensed matter system of spins coupled through antiferromagnetic exchange interaction and derive its effective electromagnetic properties. We predict that this system gives rise to the emergent dual axion field, support our conclusion by numerical simulations, and put forward candidate materials.

Soliton-based computing architectures have recently emerged as a promising avenue to overcome fundamental limitations of conventional information technologies, the von Neumann bottleneck. In this context, magnetic skyrmions have been widely considered for in-situ processing devices due to their mobility and enhanced lifetime in materials with broken inversion symmetry. However, modern applications in nonvolatile reservoir or neuromorphic computing raise the additional demand for nonlinear intersoliton interactions. Here we report that solitons in easy-plane magnets, such as bimerons and antibimerons, show greater versatility and potential for nonlinear interactions than skyrmions and antiskyrmions, making them superior candidates for this class of applications. Using first-principles and transition state theory, we predict the coexistence of degenerate bimerons and antibimerons at zero field in a van der Waals heterostructure ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2/{\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Te}}_6$—an experimentally feasible system. We demonstrate that, owing to their distinct structural symmetry, bimerons exhibit fundamentally different behavior from skyrmions and cannot be regarded as their in-plane counterparts, as is often assumed. This distinction leads to unique properties of bimerons and antibimerons, which arise from the unbroken rotational symmetry in easy-plane magnets. These range from anisotropic soliton-soliton interactions to strong entropic effects on their lifetime, driven by the nonlocal nature of thermal excitations. Our findings reveal a broader richness of solitons in easy-plane magnets and underline their unique potential for spintronic devices.

Since the discovery of superconductivity in infinite-layer nickelates, extensive research has been devoted to uncovering the underlying mechanisms of this phenomenon. Here, combining density functional theory and Wannier function calculations, we show that increasing the interlayer spacing of Nd-${\mathrm{NiO}}_2$ enhances the Ni $e_g$ orbital polarization and effective Ni $d_{x^2-y^2}$ nearest-neighboring hopping while suppressing the hybridization between Ni $d_{x^2-y^2}$ and interstitial $s$ orbitals. The pronounced two-dimensional character of the electronic structure and resultant conduction pathways may be favorable for superconductivity. Furthermore, the interlayer spacing strongly affects Fermi surface topology and pocket size around the A point in the first Brillouin zone, i.e., the self-doping effect. Given that the self-doping effect is considered a key feature distinguishing nickelates from cuprates, this may help explain why the superconducting transition temperature of cuprates is higher. Our results highlight the critical role of interlayer spacing in tuning the electronic structure of infinite-layer nickelates and suggest a feasible route to optimizing superconductivity through structural engineering.

Amorphous silicon ($a\text{-Si}$) is understood to be a canonical continuous random network material, ideally defined by fully fourfold coordination. Here, we show that a defect-free (‘‘ideal’’) model of $a\text{-Si}$ from machine-learning-driven molecular-dynamics simulations [Rosset et al., Nat. Commun. 16, 2360 (2025)], subsequently evaluated with hybrid-level density-functional theory computations, can accurately reproduce the experimentally observed electronic band gap. We compare this model with one resulting from the Wooten-Winer-Weaire bond-switching approach and with other recent approximants to ideal $a\text{-Si}$. More broadly, our work provides a platform for studies of band tails, optical properties, and transport in $a\text{-Si}$.

We investigate the steady state of two single-mode, uniform, spatially separated polaritonic condensates exposed to resonant pumping with entangled pairs of photons in the presence of incoherent exciton reservoirs created by nonresonant optical pumping. We demonstrate the principal possibility of driving the system to an entangled state despite its exposure to noises arising from the excitonic reservoirs and photon leakage through the microcavity mirrors. We estimate the minimum pair-induced polariton influx required to drive the system into a steady state that violates the partial-transpose criterion for entanglement. Furthermore, we trace the evolution of the system after a sudden switch-off of the entangled pumping. Our analysis provides estimates for the entanglement lifetime in a system of two exciton-polariton condensates.

Periodic π-vacancies in graphene superlattices (GSLs) provide a symmetry-based route to band gap opening in graphene by modifying the π-band dispersion, yet the symmetry conditions that determine whether a vacancy motif can open a band gap remain unclear. Here, we investigate periodic π-vacancy GSLs using a nearest-neighbor tight-binding model with one $p_z$ orbital per carbon site to identify the symmetry requirements for band gap opening. Here, π vacancies, resembling functionalized, substituted, or missing carbon sites, are modeled as site deletions in the π basis, and the corresponding hopping matrix elements to and from the deleted sites are set to zero. We focus on π-vacancy motifs with $C_2$ and $C_3$ point groups. A $3n\times 3n$ GSL, where $n=1,2,3,\cdots$ is the integer scaling factor multiplying the honeycomb primitive-cell vectors, is required to fold $K$ and $K^{\prime }$ to $\mathrm{\Gamma }$, which is one of the requirements for opening a band gap. For $C_3$-type vacancies, the Dirac cones are pinned at the high-symmetry points, thus remaining at $\mathrm{\Gamma }$ in the folded $3n$ GSLs. However, those $C_2$-type vacancies, which reduce the global point group of the GSL to $D_{2h}$ by preserving a pair of perpendicular mirror symmetries (${\sigma }_v\perp {\sigma }_d)$, can constrain the positions of Dirac cones at $\mathrm{\Gamma }$. The absence of the ${\sigma }_v$ and ${\sigma }_d$ planes allows the cones to shift around $\mathrm{\Gamma } \left(\pm \mathrm{\Delta }\mathbf{q},\pm \mathrm{\Delta }\mathbf{q}\right)$ in the $3n$ superlattice. The $C_3$-type vacancies open a relatively larger band gap than the $C_2$-type vacancies due to twofold degeneracy at $\mathrm{\Gamma }$, while the $C_2$-type vacancies leave the GSL with nondegenerate bands. The energy contours near the Dirac cone for $C_3$-symmetric vacancies remain isotropic, while the absence of $C_3$ generates anisotropic cones. The band gap openings in $3n$ superlattices scale linearly with defect concentration for each vacancy motif, with the $D_{6h}$ motif yielding the largest gap, reaching 314 meV at only 3.7% defect concentration. Disorder of the superlattice by missing vacancies or by vacancy displacements of one or two primitive lattice vectors of graphene breaks the $C_3$ symmetry, lifts the degeneracy, and reduces the gap toward the pristine graphene limit.

Kagome metals exhibit rich correlated-electron physics, yet a systematic understanding of the degree of correlation across transition-metal species remains elusive. Using density-functional theory plus multiorbital slave-spin mean-field theory, we investigate electronic correlations in the Ti-, V-, and Cr-based 135 compounds with Sb and Bi pnictogens. We find that the significantly stronger degree of correlation of the Cr-based materials compared to Ti and V can only be explained through the synergy of two effects: the larger electron filling of the $d$ shell and the reduced characteristic kinetic energy. We put forward that the substitution of Sb with Bi strengthens correlations in all compounds and make the prediction that the-yet-to-be-synthesized ${\mathrm{CsCr}}_3{\mathrm{Bi}}_5$ must be the most strongly correlated member of the entire family. These findings provide a quantitative, band-structure-based framework for understanding and predicting correlation strength in Kagome metals.

We study strongly interacting topological Floquet systems in one dimension and symmetry class BDI and introduce two Floquet Green's-function-based topological invariants to characterize phases hosting Majorana zero modes and Majorana $\pi$ modes at the edge. While applicable also to interacting systems, these invariants reproduce winding numbers of noninteracting Floquet unitaries discussed in the literature. We further analytically evaluate the Green's function in interacting Kitaev-like Floquet chains (or equivalently transverse field Ising circuits) both in the bulk and at the edge at various analytically tractable points in parameter space corresponding to a variety of topological phases. Just as in the case of continuum time evolution, topological bands of Green's function zeros may also contribute to the topological invariant and display a bulk-boundary correspondence. However, contrary to the case of continuum time evolution, Floquet Green's functions can have zeros even in the absence of interactions. Finally, we also discuss an implementation of this Floquet system in a digital quantum emulator: We present a circuit which encodes the interaction under consideration and pinpoint the observables carrying information about the topological Green's function boundary zeros.

One-dimensional non-Hermitian quasicrystals with parity and time-reversal ($\mathcal{PT}$) symmetry can simultaneously exhibit a localization-delocalization transition, a topological phase transition, and a $\mathcal{PT}$-symmetry-breaking transition. This motivates us to investigate how the absence of $\mathcal{PT}$ symmetry impacts topological metal-insulator transitions in non-Hermitian quasicrystals. We propose a non-Hermitian quasiperiodic model that generally does not preserve $\mathcal{PT}$ symmetry but, in most parameter regions, hosts a generic triple-transition scenario encompassing localization, topological, and degeneracy-breaking transitions. These transitions can be understood within the dual momentum-space representation featuring asymmetric couplings. Specifically, the localization boundary is obtained from the dual momentum-space representation by comparing the Lyapunov exponent, or inverse localization length, of the reciprocal Aubry-André model with the nonreciprocal hopping-asymmetry ratio of the dual lattice. The accompanying topological transition is characterized by a point-gap winding number defined with respect to a reference energy inside the complex spectral gap, whereas the degeneracy-breaking transition is understood from the loss of the reciprocal $n\leftrightarrow -n$ spectral symmetry. The system also exhibits a localization-delocalization transition analogous to that in the Hermitian case, which occurs without accompanying topological or degeneracy-breaking transitions. Our work extends the topological metal-insulator transitions previously studied in $\mathcal{PT}$-symmetric systems to a more general class with a non-Hermitian setting and further reveals that non-Hermitian systems can host distinct types of localization behavior.

Altermagnetism is a recently identified magnetic phase with zero net magnetization but momentum-dependent spin splitting, for which unambiguous experimental signatures remain scarce. We show that thin superconducting films coexisting with collinear $d$-wave altermagnetic order exhibit characteristic fourfold anisotropies in their critical temperature, in-plane critical field, and critical current density. We demonstrate that these anisotropies originate from the interplay between a paramagnetic-type coupling—generated by an exchange or Zeeman fields—and the orbital coupling also induced by the magnetic field. The altermagnetic contributions to the predicted anisotropies are odd in the applied magnetic field. Observed together with zero net magnetization, these signatures directly indicate the presence of altermagnetic order and allow it to be distinguished from anisotropies of other origins. Our results, applicable to intrinsic altermagnetic superconductors and to superconductor/altermagnetic-insulator heterostructures, provide directly measurable signatures for identifying altermagnetic order in thin-film geometries.

We perform hybrid density functional calculation to study the energetics, electronic properties, optical transitions, and migration barriers of native defects in ${\mathrm{CaWO}}_4$. Oxygen and calcium vacancies are most likely to form in the absence of doping, but interstitials could also incorporate. Tungsten-related defects are unlikely to be present. The positively charged $V_{\mathrm{O}}$ and the negatively charged $V_{\mathrm{Ca}}$ are likely to form complexes. Calculated optical transition levels indicate that experimentally observed absorption and emission peaks can be attributed mainly to oxygen-related defects. Calculations of migration barriers allow us to conclude that ${\mathrm{Ca}}_i^{2+}, V_{\mathrm{O}}^{2+}$, and ${\mathrm{O}}_i^{2-}$ are highly mobile, even below room temperature. We have also examined Er dopants, finding that erbium easily substitutes on the Ca site in a positive charge state. Erbium can form complexes with $V_{\mathrm{Ca}}$ and ${\mathrm{O}}_i$, which would deactivate the Er. If Er is introduced by implantation, Er interstitials are likely present, which will produce emission that is prone to spectral diffusion and blinking. Our calculated properties of ${\mathrm{Er}}_i$ explain why annealing at modest temperatures allows the interstitials to move into substitutional sites and point defects to move away, resulting in stable emission.

We report a comprehensive high-temperature structural investigation of the B-site ordered double perovskite ${\mathrm{SrLaCoNbO}}_6$ using combined Raman spectroscopy and x-ray diffraction (XRD) over the range 25–900 ${}^{\circ }\mathrm{C}$. Two distinct temperature-driven anomalies are identified at $T_{\mathrm{OD}}=300\pm 25{}^{\circ }\mathrm{C}$ and $T_{\mathrm{PT}}=750\pm 25{}^{\circ }\mathrm{C}$ through pronounced renormalizations in the phonon frequency and linewidth, accompanied by the evolution and suppression of characteristic XRD reflections. The low-temperature anomaly at $T_{\mathrm{OD}}$ is associated with an isostructural octahedral distortion within the monoclinic $P{2}_1/n$ phase. At $T_{\mathrm{OD}}$, the radial and angular distortion parameters of the ${\mathrm{CoO}}_6$ and ${\mathrm{NbO}}_6$ octahedra decrease to near-zero values before reversing upon further heating due to an inversion of the in-plane Co–O and Nb–O bond-length hierarchy. The high-temperature anomaly at $T_{\mathrm{PT}}$ corresponds to a symmetry-breaking structural phase transition from $P{2}_1/n$ to the monoclinic $I2/m$ phase, confirmed by group-theoretical analysis and Rietveld refinement. These results demonstrate that integrating temperature-dependent Raman spectroscopy with laboratory-based XRD, complemented by quantitative octahedral distortion analysis, provides a robust approach to disentangle isostructural octahedral distortions from symmetry-breaking phase transitions in complex double perovskite oxides without recourse to synchrotron or neutron diffraction facilities.

Long-lived hyperfine coherences in rare-earth-ion doped (REID) crystals provide controlled phase evolution windows for metrology. We use this resource to propose an experimental protocol for accessing strain shifts of ground state hyperfine transitions in non-Kramers REID materials, a quantity that is difficult to access directly with conventional spectroscopic methods. Starting from the crystal field Hamiltonian, we relate the response to strain-dependent effective quadrupole and Zeeman tensors, including changes in electronic wave functions, virtual electronic admixtures, and the bare nuclear quadrupole interaction. The protocol optically prepares a selected hyperfine class, uses a phase-controlled rf $\pi /2$ pulse to create the sensing coherence, and applies synchronized dynamical decoupling pulses during the phase evolution interval so that a coherent ac strain drive accumulates phase rather than averaging away. The accumulated phase is then retrieved by Raman heterodyne readout. The resulting framework provides a route to understanding strain-induced hyperfine shifts in non-Kramers REID systems.