A Monte Carlo framework is developed to compute the optical conductivity ${\sigma }^{xx}\left(\omega \right)$ and the Hall conductivity ${\sigma }^{xy}\left(\omega \right)$ of the spin-fermion model with thermally fluctuating local moment and is applied to study the non-Fermi-liquid transport behavior of the cuprate superconductors. Both ${\sigma }^{xx}\left(\omega \right)$ and ${\sigma }^{xy}\left(\omega \right)$ calculated are found to exhibit a two-component structure, with a Drude component at low energy and a midinfrared component at higher energy. We find that these two components can be understood as the remnants of the corresponding spectral features contributed by the intraband and interband transition in an antiferromagnetic ordered state, in which the electron band is split into the upper and the lower SDW band. For our choice of parameters, both the Drude and the midinfrared component in $\mathrm{Im}{\sigma }^{xy}\left(\omega \right)$ are found to be positive and there are two sign changes between them. We find that such sign changes can be taken as the precursor of the Fermi surface reconstruction or, more specifically, the emergence of electron pocket in the antiferromagnetic ordered state. Depending on the relative importance of the hole pocket and the electron pocket on the reconstructed Fermi surface and the coupling strength to the local moment, the Drude component in $\mathrm{Im}{\sigma }^{xy}\left(\omega \right)$ can be either positive or negative. These results imply that the Hall response in the low-frequency limit is rather subtle and may depend sensitively on the details of the low-energy physics of the system.

We present a temperature-dependent reflectivity study of single crystals of the ternary intermetallic compounds ${\mathrm{GdCu}}_2{\mathrm{Ge}}_2$ and ${\mathrm{GdCuAl}}_3$ over a broad spectral range ($100–18000{\mathrm{cm}}^{-1}$, equivalent to 12 meV–2.23 eV) down to 13 K. Below 2000 ${\mathrm{cm}}^{-1}$, the optical spectra are dominated by the response of itinerant charge carriers exhibiting two distinct scattering rates. While the response of the highly damped charge carriers shows negligible temperature dependence, the weakly damped carriers closely follow the dc resistivity and are significantly suppressed in ${\mathrm{GdCuAl}}_3$, consistent with its higher resistivity. Supported by density-functional theory calculations, we further show that elemental substitution from ${\mathrm{GdCu}}_2{\mathrm{Ge}}_2$ to ${\mathrm{GdCuAl}}_3$ tunes the X-site $p$-orbital character (X = Ge, Al) of the low-energy electronic structure, while preserving key features such as linearly dispersing bands and saddle points despite the accompanying structural modifications. The reduced experimental plasma frequency of both compounds signals enhanced electronic correlations, which induce moderate band-energy renormalization.

We study the topological phase transition in a two-leg Su-Schrieffer-Heeger (SSH) ladder by redefining the unit cell structure. For both identical hopping dimerization pattern (uniform) and alternate hopping dimerization pattern (staggered) along the legs of the ladder, we demonstrate that different unit cell choices generate different topological phases and phase transitions. In the uniformly dimerized ladder, variation of the interleg coupling induces a transition from a topological phase to another topological phase through a gapless region. In contrast, the staggered dimerization configuration exhibits a richer phase structure, supporting both topological-topological and trivial-topological transitions occurring through a single gap-closing point, depending on the unit cell definition. The phases are characterized through bulk-boundary correspondence, edge state analysis, and bulk topological invariants. Interestingly, we obtain that while all the topological phases host two zero-energy edge states each, the topological phase for the staggered dimerization case at small interleg coupling hosts four edge states. We then perform topoelectric circuit simulation and experiments to observe the signatures of the topological phases. By using circuit impedance and voltage responses we establish the emergence of distinct edge modes in the circuit. Our analysis provides a route to engineer topological edge modes in a two-leg SSH ladder setup.

We study twisted bilayer ${\mathrm{WSe}}_2$ within a continuum moiré model and apply a method for treating finite geometries directly in the continuum framework, thereby avoiding the limitations associated with purely momentum-space formulations and Wannier obstructions. By projecting a confinement potential onto bulk moiré eigenstates, we obtain a real-space description of edge physics without lattice models. Applying this approach to nanoribbons, we demonstrate chiral edge modes consistent with bulk Chern numbers and reveal their moiré-scale character. In the magic-angle regime, these states are strongly localized, exhibit layer-polarized counterpropagating modes, and are electrically tunable via a displacement field, enabling control of localization, hybridization, and topological transitions. Our results establish a general framework for boundary physics in topological moiré materials.

Spectral functions encode key many-body information but are costly to compute with high fidelity. Machine-learning surrogates have emerged as a powerful alternative, yet many approaches require large training datasets. We develop a data-efficient surrogate for spectral functions using the $t\text{−}{t}^{\prime }\text{−}{t}^{″}\text{−}J$ model, which describes the motion of a hole in a quantum antiferromagnet. Using $\sim {10}^5$ self-consistent Born approximation-based spectra from Lee, Carbone, and Yin [Phys. Rev. B 107, 205132 (2023)], we train a deep-kernel Gaussian process surrogate model with sparse variational inference (DKL-SVGP) using only 10% of the available training spectra. We benchmark against feedforward neural networks (FFNN) trained on the same reduced subset and on the full dataset. The proposed DKL-SVGP model consistently outperforms the reduced-data FFNN and, despite using only 10% of the training spectra, achieves spectrumwise errors within the same order of magnitude as the full-data FFNN baseline. Worst-tail diagnostics show improved fidelity on difficult spectra, while peak-level analysis indicates that DKL-SVGP recovers dominant peak heights with comparable accuracy and improves peak-location agreement under a matched-peak evaluation that mitigates rare peak-swapping cases. Overall, these results highlight GP-based surrogates as a competitive and data-efficient approach for spectral-function prediction in scarce-data regimes.

We investigate localization and the non-Hermitian skin effect in a one-dimensional nonreciprocal chain with unidirectional Aubry-André-Harper hopping. The interplay between nonreciprocity and quasiperiodic modulation produces rich localization behavior, including transitions among extended, critical, and localized regimes, reentrant localization, and an energy-dependent skin effect. We show that the global skin effect can be suppressed, reversed, and restored by tuning the quasiperiodic strength, which also drives a pseudo-Hermitian transition in the band structure. By analyzing participation ratios, wave-function distributions, and complex-energy spectra under periodic and open boundary conditions, we further demonstrate that spectral reconstruction provides a clear signature of the skin effect. In addition, extending the eigenspectrum to the complex plane in a ring geometry reveals a localization transition of complex-energy modes analogous to Anderson localization. These results show that unidirectional quasiperiodic hoppings offer a versatile route to controlling localization and skin physics in non-Hermitian systems.

Hexagonal MnTe has emerged as a prototypical $g$-wave altermagnet, hosting time-reversal symmetry breaking in momentum space despite a vanishing net magnetization. While this symmetry breaking theoretically allows for an intrinsic anomalous Hall effect, experimentally observed signals have remained weak. In this Letter, we investigate the origin of this suppression and demonstrate a strategy to amplify anomalous transport responses within the experimentally accessible doping regime. Using a $\mathit{k}·\mathit{p}$ effective model, we reveal that near the valence band maximum, which corresponds to the energy window relevant for typical hole doping ($\sim {10}^{19}{\text{cm}}^{-3}$), the intrinsic Hall effect is suppressed due to a symmetry-enforced cancellation of opposing Berry curvature contributions. We propose that breaking the crystalline symmetry via volume-conserving biaxial strain lifts this cancellation, resulting in a significant enhancement of the anomalous Hall conductivity by orders of magnitude. This strain-induced Fermi-surface distortion also amplifies the anomalous Nernst effect. Furthermore, the analysis of the spin texture confirms that these strain-enabled anomalous transport signatures emerge while preserving the zero net magnetization.

There is rich experimental evidence that granular superconductors and superconducting films often exhibit a higher transition temperature $T_c$ than that in bulk samples of the same material. This Letter suggests that this enhancement hinges on random matrix phonons mediating Cooper pairing more efficiently than bulk phonons. We develop the Eliashberg theory of superconductivity in chaotic grains, calculate the random phonon spectrum, and solve the Eliashberg equations numerically. Self-averaging of the effective electron-phonon coupling constant is noted, which allows us to fit the numerical data with analytical results based on a generalization of the Berry conjecture. The key insight is that the phonon density of states, and hence $T_c$, shows an enhancement proportional to the ratio of the perimeter and area of the grain—the Weyl law. We benchmark our results for aluminum films and find an enhancement of $T_c$ of about $10\%$ for a randomly generated shape. A larger enhancement of $T_c$ is readily possible by optimizing grain geometries. We conclude by noticing that mesoscopic shape fluctuations in realistic granular structures should give rise to a further enhancement of global $T_c$ due to the formation of a percolating Josephson network.

In this work, we introduce the concept of Majorana-like photonic molecules in higher-order topological photonic crystals. Here, we provide a route to combine the spectral control of conventional photonic molecules with gap-centered physics protected by symmetries. By projecting Maxwell's Hermitian operator onto a subspace of corner modes, we derive an effective Majorana-like Hamiltonian, where an analog of particle-hole symmetry enforces the Hamiltonian parameters to be real and antisymmetric. This structure organizes the spectrum into symmetric pairs and guarantees the existence of an unpaired mode, a direct feature of topological chemistry in photonic molecules. We connect this framework to accessible experimental signatures, since anticrossing patterns remain the key fingerprint inheriting symmetry protection. Finally, we validate the theory with a photonic crystal with $C_3$ symmetry harboring $p$- and $d$-orbital corner states, where the control of geometric displacements tunes the coupling and reproduces both the organization of eigenfrequencies and the anticrossing in the energy density spectrum.

In topological phases of matter, fusion rules dictate how anyonic topological charges combine. However, the transformation of quasiparticle mobility under fusion remains largely unexplored. In this Letter, we reveal that restricted mobility classes obey their own complex multichannel fusion rules. We introduce three exactly solvable models with ${\mathbb{Z}}_2$ topological order enriched by subsystem symmetries to explicitly demonstrate these structures. Within these models, mobility constraints arise from enforcing symmetries supported on specific subsets. When excitations fuse, these rigid geometric constraints interfere spatially. At the macroscopic level, this deterministic geometric interference manifests as multichannel fusion rules. We present three explicit examples: (i) Fibonacci fusion rules, (ii) tensor products of Fibonacci rules, and (iii) lineon period transmutation.

Boron vacancies ($V_B^{-}$) in hexagonal boron nitride (hBN) have emerged as a promising platform for two-dimensional (2D) quantum sensors capable of operating at atomic-scale proximity. However, the mechanisms responsible for photoluminescence quenching in thin hBN sensing layers when placed in contact with absorptive materials remain largely unexplored. In this Letter, we investigate nonradiative Förster resonance energy transfer (FRET) between $V_B^{-}$ centers and either monolayer graphene or 2D semiconductors. Strikingly, we find that the FRET rate is negligible for hBN sensing layers thicker than 3 nm, highlighting the potential of $V_B^{-}$ centers for integration into ultrathin quantum sensors within van der Waals heterostructures. Furthermore, we experimentally extract the intrinsic radiative decay rate of $V_B^{-}$ defects.

We theoretically study the direct and inverse spin Hall effects in a superconductor-normal metal-superconductor junction induced by a spin-orbit interaction that is invariant under spatial inversion. We show that a supercurrent induces a spin Hall effect, leading to a static spin accumulation with opposite polarizations at the two edges, analogous to that in normal conductors. For the inverse effect, we consider a spatially inhomogeneous static magnetic field and show that it induces an anomalous phase shift, which, in the presence of higher harmonics, results in a diode effect. Unlike Rashba systems studied previously, the present mechanism does not require broken structural inversion symmetry, since an inhomogeneous magnetic field, equivalent to a spin current, breaks the inversion symmetry extrinsically.

We report a comprehensive investigation of the quasi-one-dimensional spin-chain compound ${\mathrm{Ca}}_3{\mathrm{CoIrO}}_6$ (CCIO) using x-ray and neutron diffraction, dc and ac magnetization, specific heat, electrical resistivity, Raman spectroscopy, and polarization–electric-field measurements. The results reveal a gradual evolution of partially disordered antiferromagnetic (PDA) correlations below $T_2\approx 100$ K, followed by freezing of the disordered spin component below $T_1\approx 30$ K. Ac susceptibility and magnetic relaxation measurements demonstrate slow spin dynamics in the intermediate-temperature regime, while the low-temperature state exhibits a large exchange-bias effect under both zero-field-cooled and field-cooled conditions. A field-induced anomaly observed in both magnetization and magnetic specific heat for fields (≳30 kOe) is attributed to the reorientation of the magnetically disordered chain fraction within the PDA framework. Raman spectroscopy reveals the emergence of an additional spectral feature together with anomalies in the dominant ${\mathrm{IrO}}_6$ stretching mode below $T_2$, indicating spin-lattice coupling associated with the development of magnetic correlations. Neutron diffraction detects no crystallographic phase transition, while polarization–electric-field measurements reveal a temperature-dependent crossover from dielectric to resistive behavior that closely follows the magnetic phase evolution. These results establish CCIO as a frustrated quasi-one-dimensional system in which geometric frustration, spin-orbit coupling, and low dimensionality cooperate to produce a field-tunable PDA state with coupled magnetic and lattice responses.

Pressure-induced superconductivity in ${\mathrm{FePSe}}_3$ was initially attributed to a spin-state transition, drawing parallels with magnetic fluctuation-mediated pairing in iron-based superconductors. This magnetic-centric view was later challenged by the discovery of superconductivity in nonmagnetic analogs such as ${\mathrm{SnPSe}}_3$ and ${\mathrm{HgPSe}}_3$, yet those cases were invariably accompanied by structural distortions, leaving the origin of superconductivity unresolved. Here, we report pressure-induced superconductivity in the nonmagnetic compound ${\mathrm{CdPSe}}_3$. No structural transition can be observed down to 80 K. Superconductivity emerges following a six-orders-of-magnitude decrease in electrical resistance, while the crystal symmetry remains unchanged. This observation raises the possibility that neither structural transitions nor magnetic ordering are required for superconductivity in this family. First-principles calculations support the experimental results and reveal an active role for chalcogen $p$ electrons in the superconducting mechanism. Our findings provide a unified understanding of the pressure-induced superconductivity in the $M\mathrm{P}{X}_3$ family and suggest that this material platform hosts a wealth of promising superconducting candidates.

We report the magnetic properties of a series of lithium-rich antiperovskites (${\mathrm{Li}}_{2}M)Ch\mathrm{O}$ ($M=\mathrm{Fe},\mathrm{Co},\mathrm{Mn}$ and $Ch=\mathrm{Se},\mathrm{S}$), where transition metal and lithium ions are randomly distributed on the X sites of the ${\mathrm{X}}_3\mathrm{BA}$ structure, thereby forming a strongly diluted magnetic sublattice. Our study hence enables us to investigate the evolution of magnetic order at fixed 1/3 filling—which is in the vicinity but slightly above the percolation threshold—upon variation of the spin size, the magnetic anisotropy, and the orbital configuration. The data imply the absence of a distinct Curie-Weiss behavior up to 350 K but show rather large and weakly temperature-dependent magnetic susceptibility. We observe clear signatures of long-range antiferromagnetic order evolving in the 1/3-filled and strongly diluted magnetic X-site lattice with increasing Néel temperatures from $T_{\mathrm{N}}\simeq 30\mathrm{K}$ in (${\mathrm{Li}}_2\mathrm{Mn}$)$Ch\mathrm{O}$ to $\simeq 50\mathrm{K}$ in (${\mathrm{Li}}_2\mathrm{Fe}$)$Ch\mathrm{O}$ and $70-90\mathrm{K}$ in (${\mathrm{Li}}_2\mathrm{Co}$)$Ch\mathrm{O}$. Except for $M=\mathrm{Co}$, the chalcogenide has no sizable effect on $T_{\mathrm{N}}$. We conclude significant magnetic coupling and short-range magnetic correlations at well above $T_{\mathrm{N}}$, which is in line with the observation of a broad electron spin resonance signal at room temperature. The actual ordering temperatures are strongly diminished by magnetic dilution. While structural parameters such as the tolerance factor and bonding angles do not strongly affect $T_{\mathrm{N}}$, a key parameter is the magnetic anisotropy of the transition metals.

The emergence of superconductivity in quasiperiodic systems poses a fundamental question: Can conventional superconductivity survive as translational symmetry is progressively lost toward the quasiperiodic limit? Quasicrystal approximants, which share the same local atomic motifs as quasicrystals while retaining periodicity, provide an ideal platform to address this issue. Here, we report bulk superconductivity in the Tsai-type 2/1 approximant ${\mathrm{Au}}_{64}{\mathrm{Al}}_{22}{\mathrm{La}}_{14}$, which possesses a giant cubic unit cell with nearly 730 atoms. Electrical resistivity, magnetic susceptibility, and specific-heat measurements consistently reveal a superconducting transition at $T_{\mathrm{c}}=0.50\mathrm{K}$. The specific-heat jump ratio $\mathrm{\Delta }C/\left(\gamma T_{\mathrm{c}}\right)=1.27$ indicates weak-coupling superconductivity consistent with a phonon-mediated Bardeen-Cooper-Schrieffer mechanism. These results demonstrate that conventional superconductivity remains remarkably robust even in a structurally complex giant unit cell approximant approaching the quasiperiodic limit. Our findings establish high-order Tsai-type approximants as an important bridge between conventional periodic and quasiperiodic superconductors and provide a key step toward realizing superconductivity in true quasicrystals, distinct from disorder-driven amorphous systems.

The control of antiferromagnets by magnetic fields represents a fundamental challenge in condensed matter physics, owing to their fully compensated magnetic order and vanishing net magnetization. Conventional methods rely on either uncompensated moments or high-field spin-flop transitions. Here, we demonstrate low-field switching in the fully compensated antiferromagnet CeNiAsO—a material recently proposed as a candidate for $p$-wave magnetism. Using an in-plane magnetic field well below the spin-flop threshold, we selectively stabilize one of two degenerate antiferromagnetic domains with mutually orthogonal sublattice orientations. This field-induced domain selection allows reversible and nonvolatile switching of a giant in-plane resistivity anisotropy up to $\sim 35$%—a magnitude that far exceeds conventional anisotropy signals driven by spin-orbit coupling. The switching behavior persists across both the low-temperature noncollinear Néel phase and the higher-temperature collinear spin-density-wave phase, highlighting the universality of the domain-selection mechanism. Our work establishes an approach for manipulating compensated antiferromagnets with modest magnetic fields and underscores their potential for high-performance spintronic devices based on giant and switchable resistivity anisotropy.

In electrides, interstitial anionic electrons (IAEs) constitute a key electronic degree of freedom whose spatial organization governs the electronic structure and emergent quantum properties. However, controlled realization of IAEs with complex topologies remains a central challenge. Here we propose a heterometallic competitive polarization strategy to engineer IAEs in a high-pressure Li-Mg-P system, leading to the stabilization of a ${\mathrm{Li}}_6{\mathrm{Mg}}_2\mathrm{P}$ electride. The intrinsic chemical inequivalence between Li and Mg induces divergent coordination responses, reconstructing the interstitial confinement potential into inequivalent Mg-centered cavities. This dual-cavity landscape stabilizes two electronically distinct black-phosphorene-like IAEs with different charge densities and localization strengths. Among them, the more delocalized IAE(2) dominates the electronic states near the Fermi level, thereby governing low-energy electronic excitations. This interstitial-state-dominated electronic structure strongly couples to low-frequency lattice vibrations of the metal framework, with IAE(2) playing the primary role in mediating electron-phonon interactions. As a result, enhanced coupling between interstitial electrons and lattice dynamics gives rise to pressure-enhanced superconductivity. These results establish heterometallic competitive polarization as an effective route for engineering nontrivial IAE topologies and provide a design principle for emergent quantum phenomena in high-pressure electrides.

Interior-gap superconductivity has long been discussed as an exotic paired state in the presence of Fermi-surface mismatch, but its realization in canonical strongly correlated models has remained elusive. Here we present evidence that the superconducting phase of one-dimensional Kondo-Heisenberg models realizes an interior-gap pair density wave (PDW) state generated by strong correlations. Combining infinite density-matrix-renormalization-group (iDMRG) and finite DMRG calculations for $S=1/2$ and $S=3/2$ chains, we show that the PDW correlation is the dominant bulk superconducting correlation in the spin-gapped regime and that the momentum distribution function $n\left(k\right)$ exhibits a reconstructed structure characteristic of interior-gap physics. In particular, while the feature in $n\left(k\right)$ for the $S=1/2$ chain is only humplike, the corresponding structure in the $S=3/2$ chain develops into a clear dip, strongly supporting the interpretation in terms of an interior-gap-like dip structure. Unlike conventional interior-gap scenarios based on a mismatch between preexisting Fermi surfaces, the present system starts from a single bare conduction-electron Fermi surface, and the additional low-energy single-particle structure emerges dynamically together with the dominant PDW correlation through the Kondo coupling. Finite DMRG data further demonstrate that boundary effects can substantially modify real-space correlations in this gapless one-dimensional system, making a direct thermodynamic-limit calculation essential for identifying the intrinsic bulk momentum structure and the dominant correlation channel.