The dense Kondo lattice ${\mathrm{Ce}}_5{\mathrm{CoGe}}_2$ exhibits superconductivity after the magnetic ordering is suppressed by pressure. Here the ambient pressure magnetic state is investigated via magnetization, heat capacity, powder neutron diffraction, and muon-spin relaxation measurements. Neutron diffraction results reveal a noncollinear ferromagnetic structure, where the four inequivalent Ce sites exhibit different magnetic moments. Point-charge model calculations of the crystalline electric field (CEF) ground states corroborate different moments between the sites, and suggest sizable components of the moments along different directions, consistent with the noncollinear structure. Analysis of the Dzyaloshinskii-Moriya (DM) interaction for the bonds connecting Ce atoms demonstrates that most of these bonds exhibit a nonzero DM vector, suggesting that competition between intersite magnetic exchange interactions, CEF driven single-ion anisotropy, the Kondo effect, and the DM interaction may drive the noncollinear ferromagnetism.

The 112-type ternary pnictides often exhibit intriguing physical properties arising from their two-dimensional layered structures. Here, we report two new members of this family, ${\mathrm{CeMg}}_{0.66}\mathrm{S}{\mathrm{b}}_2$ and ${\mathrm{PrMg}}_{0.73}\mathrm{S}{\mathrm{b}}_2$, which possess the highest $c/a$ ratio and the lowest magnetic ordering temperature among known compounds in this series. The small ${\mathrm{Mg}}^{2+}$ results in such a high lattice anisotropy and plays a role of chemical pressure, which helps to drive the Ce/Pr magnetic ordering close to a quantum critical point. Single-crystal x-ray diffraction confirms that both compounds have the two-dimensional square nets of Ce/Pr and Sb atoms and large $c/a$ ratio. Magnetic measurements reveal anisotropic magnetic ground states: ${\mathrm{CeMg}}_{0.66}\mathrm{S}{\mathrm{b}}_2$ shows in-plane ferromagnetic ordering at $T_{\mathrm{c}}=2.44$ K, and out-of-plane antiferromagnetic ordering at $T_{\mathrm{N}}=2.47$ K; ${\mathrm{PrMg}}_{0.73}\mathrm{S}{\mathrm{b}}_2$ exhibits in-plane antiferromagnetic order at $T_{\mathrm{N}}=2.36$ K, while no magnetic ordering is observed out of plane. These findings expand the 112-type pnictide family and offer a valuable platform for studying low-temperature magnetism in layered square-net systems. Furthermore, by comparing isostructural analogs, we establish an empirical correlation between the $c/a$ ratio and the magnetic transition temperature, providing a practical guideline for the targeted design of new 112-type materials.

Non-Hermitian systems exhibit many unique properties, particularly the phenomena near exceptional points, which have garnered significant attention. In this work, we obtain an exact solution for a one-dimensional non-Hermitian XY model with Dzyaloshinsky-Moriya (DM) interaction, focusing on its quantum entanglement and chiral critical phenomena. Our results reveal that the DM interaction breaks the system's rotation-time-reversal symmetry and quasi-long-range order, leading to the emergence of two distinct chiral phases and a quantum critical point (QCP). The DM interaction is found to enhance the entanglement entropy in chiral phases I and II, whereas it leaves the entropy unchanged in the paramagnetic phase. Notably, the entanglement entropy exhibits a crossover behavior in the vicinity of the QCP. Furthermore, we investigate the critical behavior of the chiral order parameter near the QCP, establishing a relation between the chiral critical exponent $\theta$ and the magnetization exponent $\beta$ as $\theta =2\beta$. A key finding is that while entanglement entropy solely characterizes the transition at the QCP, the chiral order parameter serves as a more universal probe, identifying transitions at both the exceptional point and the QCP.

Cagelike carbon frameworks, characterized by robust covalent bonding and unique topological motifs, offer a fertile ground for the discovery of high-temperature superconductors under ambient conditions. Inspired by Archimedean polyhedral geometry, we propose a carbon cage structure, ${\mathrm{C}}_{48}$, featuring cubic symmetry and dynamic stability at ambient pressure. Leveraging this framework, we applied a guest-host engineering approach to systematically explore 961 binary and ternary compounds of the form $XY{\mathrm{C}}_{24}$ via high-throughput density functional theory calculations, in which the guest elements $X$ and $Y$ are located at the cage corners and body center, respectively. Through stringent stability and metallicity screening, we identified 123 compounds that are both dynamically stable and metallic at ambient pressure, all of which exhibit intrinsic superconductivity. Notably, our analysis reveals a necessary correlation between the dynamical stability of these compounds and the atomic radius of the guest atoms, highlighting the critical role of size compatibility in stabilizing the host-guest framework. Moreover, five of these superconductors exhibit critical temperatures ($T_c$) exceeding the McMillan limit. Among them, ${\mathrm{NaRbC}}_{24}$ and ${\mathrm{TlKC}}_{24}$ demonstrate ideal superconducting properties, with $T_c$ reaching as high as 70.7 and 75.2 K, respectively. The high $T_c$ originates from strong electron-phonon coupling driven by pronounced Fermi surface nesting and carbon-dominated electronic states at the Fermi level. Our findings highlight the critical role of guest atom size in stabilizing the structure and enhancing superconductivity. This work not only enriches the family of carbon-based superconductors but also establishes polyhedral cage design as a powerful paradigm for the targeted discovery of ambient-pressure high-temperature superconductors.

We study the entanglement asymmetry for the space-inversion symmetry of free fermions on a two-dimensional honeycomb lattice with an on-site energy imbalance between the two sublattices. We show that the entanglement asymmetry of a local subsystem exhibits nonanalytic dependence on the energy imbalance, due to the presence of Dirac points in the Brillouin zone. We also study the quench dynamics from the ground state into the inversion-symmetric point at which the energy imbalance vanishes. Under certain conditions on the subsystem geometry, the entanglement asymmetry relaxes to a finite value after the quench, revealing that the inversion-symmetry breaking in the initial ground state can persist even under the symmetric dynamics. We attribute the absence of symmetry restoration to the presence of a flat energy dispersion (flat band) in a specific direction.

We present a unified quantum field theory for Dirac magnons coupled to emergent gauge fields. At zero temperature, any space- and time-dependent gauge perturbation drives magnons out of equilibrium, generating spin currents and magnon accumulation without conventional thermal or chemical-potential gradients. For a honeycomb ferromagnet, we derive closed-form expressions for the induced density and current. In the dc limit, the transverse spin conductivity approaches ${\sigma }^{xy}={\alpha }^2\mathrm{sgn}\left(m\right)\hslash /4\pi$, revealing a response governed by a universal topological coefficient of the gapped Dirac spectrum and a coupling-dependent magnitude. In the ac regime, the conductivity exhibits a sharp resonance when the drive frequency matches the topological gap $\mathrm{\Delta }$, signaling interband transitions. Our work establishes a unified gauge-invariant framework for controlling magnon transport and highlights topological signatures in gauge-driven magnon responses.

Recent experiments have reported chiral time-reversal broken superconductivity in $n$-layer rhombohedral graphene for $n=4,5,\text{and}6$. Introducing a moiré potential by alignment with a hexagonal boron nitride substrate suppresses the superconductivity but leads instead to various fractional quantum anomalous Hall phenomena. Motivated by these observations, we consider the fate of the phase transition between (a chiral) Landau Fermi liquid (LFL) metal and a composite Fermi liquid (CFL) metal in the presence of attractive interactions. These are parent states, respectively, for the superconductor and the fractional quantum Hall states. For weak attractive interactions, the LFL is usually unstable to superconductivity while the CFL is stable. This raises the possibility of a direct continuous phase transition between the chiral superconductor and the CFL. However, we show that generically the LFL close to the transition to the CFL is stable against superconductivity. Thus the evolution between the CFL and chiral superconductor goes through an intermediate stable LFL phase for weak attractive interactions. With stronger interactions, the evolution can instead go through a non-Abelian paired quantum Hall state.

We construct asymptotic quantum many-body scars (AQMBS) in one-dimensional $\mathrm{SU}\left(N\right)$ Hubbard chains ($N\ge 3$) by embedding the scar subspace into an auxiliary Hilbert subspace ${\mathcal{H}}_P$ and identifying a parent Hamiltonian within it, together with a corresponding extension of the restricted spectrum-generating algebra to the multiladder case. Unlike previous applications of the parent-Hamiltonian scheme, we show that the parent Hamiltonian becomes the $\mathrm{SU}\left(N\right)$ ferromagnetic Heisenberg model rather than the spin-1/2 case, so that its gapless magnons realize explicit AQMBS of the original model. Working in the doublon-holon subspace, we derive this mapping, obtain the one-magnon dispersion for periodic and open boundaries, and prove (i) orthogonality to the scar states, (ii) vanishing energy variance in the thermodynamic limit, and (iii) subvolume entanglement entropy with rigorous MPS/MPO bounds. Our results broaden the parent-Hamiltonian family for AQMBS beyond spin-1/2 and provide analytic, low-entanglement excitations in $\mathrm{SU}\left(N\right)$-symmetric systems.

Magnetic octupole (MO) currents have recently attracted significant attention as a driving force for the Néel vector dynamics in $d$-wave altermagnets, a unique class of antiferromagnets that exhibit nonrelativistic spin-split band structures. From a symmetry perspective, the MO includes an axial-dipole component analogous to that of the spin, making it essential to clarify how MO currents differ from spin currents. We here investigate the correspondence between MO conductivities and electronic multipoles, which provide a unified and powerful framework for symmetry analysis. We derive the multipole representation of the rank-5 MO conductivity tensor and classify its symmetry-allowed components for all crystallographic point groups, in direct comparison with spin conductivity. We show that time-reversal-even electric-type multipoles give rise to the dissipationless MO current, whereas time-reversal-odd magnetic-type multipoles generate dissipative MO current under an applied electric field. Complementing this macroscopic analysis, the linear-response calculations for a microscopic tight-binding model demonstrate how MO conductivities are activated by symmetry lowering, exemplified by the symmetry reduction from $m\overline{3}m$ to $m\overline{3}$. Our results elucidate the symmetry distinctions between MO currents and spin currents and provide insights into their experimental identification.

We provide a general machine learning methodology that integrates classical shadow representations with unsupervised principal component analysis (PCA) to explore various quantum phase transitions. By sampling spin configurations from random Pauli measurements, our approach can effectively analyze hidden statistical patterns in the data, thereby capturing the distinct signatures of quantum criticality through their fluctuations. We benchmark this approach across various spin-1/2 systems, including the 1D XZX cluster-Ising model, the 1D bond-alternating XXZ model, the 2D transverse-field Ising model, and the 2D Kitaev honeycomb model. We show that PCA not only reliably detects and distinguishes both symmetry-breaking and topological transitions, but also enables their qualitative classification based on characteristic fluctuation patterns. Our data-driven approach does not require any knowledge of the Hamiltonian or explicit order parameters, and can therefore be a general and applicable tool for probing new quantum phases.

We construct an exactly solvable model of a four-dimensional Kitaev spin liquid. The lattice structure is orthorhombic and each unit cell contains six sublattice degrees of freedom. We demonstrate that the Fermi surface of the model is made up of two-dimensional surfaces. Additionally, we evaluate the energy cost of creating visons using scattering theory. The positive bond-flip energy suggests that the flux-free state is locally stable. Our model sheds light on the realization of high-dimensional fractionalization.

The square-net materials ${\mathrm{GdSb}}_x{\mathrm{Te}}_{2-x-\delta }$ provide a platform for exploring the effects of charge density wave (CDW) distortion and band filling on the topological electronic band structure. In this work we use infrared spectroscopy to probe the temperature-dependent electronic excitations in ${\mathrm{GdSb}}_{0.56}{\mathrm{Te}}_{1.35}$ and ${\mathrm{GdSb}}_{0.45}{\mathrm{Te}}_{1.50}$ single crystals for different polarization directions parallel to the square-net layers. First-principles calculations were also performed to study the electronic band structure and interband optical conductivity of stoichiometric GdSbTe. For ${\mathrm{GdSb}}_{0.56}{\mathrm{Te}}_{1.35}$ the in-plane optical conductivity is independent of the polarization direction and contains a small Drude term, indicating a weak metallic character, and a pronounced near-infrared absorption band, which may be due to excitations across the CDW gap. Upon cooling, the optical response shows no significant temperature dependence within the experimental uncertainty, and no signatures associated with magnetic ordering are detected. In comparison, for ${\mathrm{GdSb}}_{0.45}{\mathrm{Te}}_{1.50}$ we observe an in-plane anisotropy and strongly reduced low-frequency optical conductivity, with small temperature dependence. Possible signatures of Dirac fermion excitations in the optical conductivity spectra are also analyzed and discussed. Our results demonstrate that small differences in the stoichiometry have a significant impact on the optical response of ${\mathrm{GdSb}}_x{\mathrm{Te}}_{2-x-\delta }$ materials.

Band convergence is a traditional strategy to optimize the electrical transport properties of SnTe, but conventionally optimized band structures often retain the valence band maximum (VBM) at the low-degeneracy L point $(N\mathrm{v}=4)$. Moreover, the mechanisms of phonon softening remain poorly understood in terms of phonon dispersion, especially regarding the coupling between vacancies and other dopants. Here, the strategic incorporation of ternary ${\mathrm{MnSb}}_2{\mathrm{Te}}_4$ into SnTe via nonstoichiometric alloying introduces a synergistic effect of Sn vacancies and Mn dopants. This synergy weakens the Sn-s/Te-p antibonding state, leading to significant band renormalization. Specifically, the VBM shifts from the L point to the high-degeneracy Σ and Λ points ($N\mathrm{v}=12$ and 8, respectively), where the VBM at these two sites form perfect alignment, substantially enhancing the density-of-states effective mass. In terms of phonon dispersion, both Mn atoms and Sn vacancies soften optical phonon modes at the Γ point, reducing their frequencies from 0.9 THz to 0.3 and 0.6 THz, respectively, forming a pronounced optical-phonon “waterfall” effect. This results in a significant reduction in phonon group velocities and introduces additional optical-acoustic phonon interactions. These combined effects yield a highly optimized thermoelectric quality factor in SnTe-${\mathrm{MnSb}}_2{\mathrm{Te}}_4$ alloys. By further tuning the reduced Fermi level through Ge doping, we achieve a maximum ZT of 1.3 at 723 K and an average ZT of 0.83 (300–823 K), offering a promising pathway for mid-temperature waste heat recovery and shedding light on vacancy engineering in thermoelectrics.

We introduce a light-matter interface that integrates a nanoscale buried heterostructure emitter into a dielectric bowtie cavity, colocalizing the optical hotspot and the electronic wavefunction. This platform enables strong light-matter interaction through deep subwavelength confinement while remaining compatible with scalable fabrication. We show that in this regime an explicit treatment of the emitter's spatial extent is required, and that a confinement-factor approximation more accurately predicts the coupling, revealing design rules inaccessible to dipole-based metrics. For an InP/InGaAsP system, we predict coupling strengths of $0.4–0.7\mathrm{meV}$ for gap sizes of $50–10\mathrm{nm}$, establishing the buried heterostructure-bowtie architecture as a practical route to deterministic strong coupling in solid-state nanophotonics.

We present a comprehensive analysis of magnetotransport across monolayer $1T^{\prime }\text{−}{\mathrm{WTe}}_2$, highlighting the role of nonsymmorphic symmetries in governing edge-state spin behavior. By comparing the electronic transmission in nanoribbons with edges along the crystallographic $\widehat{y}$ and $\widehat{x}$ directions, our analysis reveals a pronounced anisotropy in the magnetic-field response. The $\widehat{y}$-edge ribbon exhibits significant spin splitting of the edge-state bands in both energy and momentum space, together with a strong angular dependence of the conductance. The observed magnetotransport response indicates a spin quantization axis that aligns with the out-of-plane spin quantization axis reported in previous experimental studies. In contrast, the $\widehat{x}$-edge ribbon shows negligible spin splitting with magnetic fields, which is attributed to nonsymmorphic symmetries such as glide mirror and screw rotation, which protects degeneracies along the $\mathrm{\Gamma }\text{−}X$ direction, even when time-reversal symmetry is broken. The energy-resolved current density and angular transmission analysis confirm that this anisotropy originates from edge states, while bulk states remain largely insensitive to the field orientation. Our results establish direct transport spectroscopy based evidence of nonsymmorphic symmetry-protected spin degeneracy in $1T^{\prime }\text{−}{\mathrm{WTe}}_2$, and underscore its promise for spintronic devices that leverage symmetry-protected and directionally selective transport channels.

Motivated by recent experiments on multiterminal Josephson junctions (MJJs) that probe different ranges of the size and bias voltage parameters, we explore the regime of increasing bias voltage in large-scale devices, where the electrochemical potential becomes comparable to the one-dimensional energy level spacing. We find that the relative number of quantum-correlated pairs formed by colliding Floquet-Kulik quartet levels is equal to the inverse of the number of channels. This observation motivates a model for the intermediate regime in which the ballistic central two-dimensional normal metal is treated as a continuum under the adiabatic approximation, while Andreev modes propagate in a background of voltage- and flux-tunable nonequilibrium electronic populations. The model predicts characteristic voltage scales that govern the mesoscopic oscillations of the critical current, and these scales are at the crossroads of interpreting experiments in all sectors of the MJJs: quartets, topology, and Floquet theory. Our model is specifically inspired by the recent Harvard and Penn State group experiments.