We analyze the magnetization curve of the spin-1/2 kagome Heisenberg model in a magnetic field. Using state-of-the-art variational wave functions based on neural networks, we confirm the presence of robust magnetization plateaus at $m=1/3$, $5/9$, and $7/9$ of the saturation value, stabilized by a spontaneous symmetry breaking of lattice translations with a $\sqrt{3}\times \sqrt{3}$ unit cell. Regarding the more challenging $m=1/9$ plateau, we find two competing valence bond crystals depending on the system size, both breaking translation as well as point group symmetries and with a larger $3\times 3$ unit cell. Such quantum states with local modulations of the magnetization average values could be observed experimentally in the near future.

Altermagnets, characterized by vanishing net magnetization and momentum-dependent spin-splitting, offer a unique platform for high-performance spintronic devices. Here, we propose a double-barrier altermagnetic tunneling junction, and investigate the spin transport properties of ${\mathrm{RuO}}_2/{\mathrm{TiO}}_2/{\mathrm{RuO}}_2/{\mathrm{TiO}}_2/{\mathrm{RuO}}_2$ by using first-principles calculations combined with the nonequilibrium Green's function method. A giant tunneling magnetoresistance (TMR) of up to 75 094% is achieved at optimal geometry, which is much higher than that of $200-500\%$ for the single-barrier altermagnetic tunneling junction of ${\mathrm{RuO}}_2/{\mathrm{TiO}}_2/{\mathrm{RuO}}_2$. The transport is governed by momentum-selective resonant tunneling through quantum-well (QW) states formed in the altermagnetic ${\mathrm{RuO}}_2$ spacer. Due to the intrinsic $k$-dependent spin splitting of ${\mathrm{RuO}}_2$, the resonance condition is satisfied at distinct ${\vec{k}}_{\left|\right|}$ points for different spin channels, giving rise to localized transmission hot spots near the Brillouin-zone corners. In the parallel configuration, these QW states align with the Fermi level and support near-unity transmission, whereas reversing the Néel vector disrupts the resonance condition and suppresses transmission across the Brillouin zone, leading to the large TMR. By analyzing the dependence on QW thickness and barrier thickness, we show that the transport is controlled by the interplay of quantum confinement, total broadening, and coupling symmetry. High transmission is achieved when the QW states are properly aligned and the coupling to the electrodes is both strong and symmetric. These results provide a microscopic understanding of altermagnetism-driven resonant tunneling and offer a route to enhancing TMR through momentum-selective transport.

The intrinsic superconducting diode effect (SDE) is distinguished from the Josephson diode effect by its manifestation of nonreciprocal critical current phenomena within a monolithic superconductor, typically linked to finite-momentum Cooper pairing. The long-standing assumption that SDE requires cobreaking of time-reversal and inversion symmetries proves to be necessary but not sufficient. In this work, we propose an algebraic diagnostic criterion for intrinsic SDE, expressed as two inequalities evaluated directly from the bare Hamiltonian. This criterion further reveals a graph-theoretic construction for nonreciprocal models, offering design principles that extend beyond superconductivity.

We investigate Higgs criticality in candidate U(1) Dirac spin liquids across a family of depleted triangular lattices: the triangular, kagome, and maple-leaf geometries. For each, we identify the symmetry-allowed spinon-pairing channel connecting the U(1) state to a proximate ${\mathbb{Z}}_2$ spin liquid, deriving the corresponding quantum electrodynamics $\left({\mathrm{QED}}_3\right)$-Higgs theory. While the triangular and kagome lattices share a low-energy description with $N_f=4$ Dirac fermions, the maple-leaf lattice yields an analogous theory with $N_f=12$ and a distinct nodal structure where the Dirac cones can move along high-symmetry lines in momentum space instead of gapping out. Using a large-$N_{f,b}$ expansion, we compute critical exponents and the scaling dimensions of the symmetry-allowed Yukawa couplings. Although Higgs-field fluctuations and a large fermion flavor number strongly suppress the Yukawa coupling—pushing the maple-leaf lattice closer to stability than its counterparts—we find that the coupling remains relevant at leading order in all three cases, substantially reducing its scaling dimension on the maple-leaf lattice and asymptotically breaking Lorentz and conformal invariance. Ultimately, our results provide a unified framework demonstrating how the interplay between fermion flavor count and nodal geometry dictates the fate of the ${\mathrm{QED}}_3$-Higgs transition.

The microscopic magnetic model of the low-dimensional quantum magnet α-${\mathrm{Cu}}_2{\mathrm{P}}_2{\mathrm{O}}_7$ has remained controversial. We present a comprehensive study of its magnetic ground state and excitation spectrum using temperature-dependent inelastic neutron scattering, neutron diffraction, magnetization measurements, and comprehensive spin-wave modeling. Our results unambiguously establish α-${\mathrm{Cu}}_2{\mathrm{P}}_2{\mathrm{O}}_7$ as a two-dimensionally coupled spin-dimerized antiferromagnetic (AF) lattice within the $bc$ plane, with a dominant AF exchange $J_2=7.73\pm 0.02$ meV (hereafter referred to as the ‘‘intradimer exchange’’) and weaker exchange couplings $J_1$, $J_3$, and $J_4$ in the two-dimensional lattice (hereafter referred as ‘‘interdimer exchange’’), in agreement with LDA-based density functional theory and in contrast to previous GGA+U predictions. The dominant intradimer AF exchange is found between the seventh-nearest-neighbor Cu–Cu ion pairs $[d_{\mathrm{Cu}-\mathrm{Cu}}=5.125\left(3\right)\AA ]$ rather than the nearest-neighbor Cu–Cu ion pairs $[d_{\mathrm{Cu}-\mathrm{Cu}}=3.014\left(1\right)\AA ]$ of the structural dimers. Weak interlayer coupling $(J_5=0.03\pm 0.01 \mathrm{meV})$ stabilizes long-range antiferromagnetic order below $T_N\approx 25$ K. We further identify a weak single-ion anisotropy, associated with the distorted ${\mathrm{CuO}}_5$ polyhedra that opens a gap in the spin-excitation spectrum and drives a field-induced metamagnetic transition. Systematic spin-wave calculations elucidate the distinct roles of interlayer coupling $J_5$ and the anisotropy term $D$ in producing two distinct energy gaps at different antiferromagnetic zone centers. Complementary neutron diffraction and magnetization measurements as a function of applied magnetic field uncover a previously overlooked metamagnetic transition near 13 kOe and allow the construction of the magnetic phase diagram in the H-T plane. Our results unambiguously establish α-${\mathrm{Cu}}_2{\mathrm{P}}_2{\mathrm{O}}_7$ as a realization of a two-dimensionally coupled spin-dimerized AF lattice with weak interlayer coupling and magnetic anisotropy, and thus resolve the discrepancy in the microscopic magnetic model. The present findings also highlight the importance of extended exchange pathways and subtle anisotropic exchange interactions in governing the ground state and excitation spectrum of low-dimensional quantum magnets.

The generation of electron orbital angular momentum (OAM) is the key for the field of orbitronics. Recently, the observation of orbital Seebeck effect [Y. Nabei et al., Nat. Phys. 22, 245 (2026)] shows that OAM can be generated by chiral phonons in materials with broken inversion symmetry. However, how electron-chiral phonon (ECP) interaction affects electric-field-induced electronic OAM dynamics remains unclear. In this work, we investigate ECP-mediated electronic OAM dynamics in a one-dimensional helical chain described by a Su-Schrieffer-Heeger model. The microscopic electronic OAM is defined from the operator ${\widehat{L}}_j^{\mathrm{el}}={\widehat{\mathbf{r}}}_j\times {\widehat{\mathbf{P}}}_j$, while the main dynamical calculations employ a phonon OAM-based approximation whose validity is benchmarked against the microscopic electronic OAM. We show that, under the local-equilibrium-center definition and in the electron-phonon coupling regime used in the main calculations, this approximation captures the main dynamical features of electronic OAM. The slowly varying axial component is associated with an orbital-Edelstein-like electronic OAM polarization, whereas the transverse components mainly exhibit coherent precessional dynamics. We further find that chirality controls the sign and dynamical pattern of electronic OAM, while spin-orbit coupling is not the dominant channel for the ECP-driven electronic OAM dynamics in the present model.

We study theoretically the impact of disorder on magnon properties and thermal Hall transport in a two-dimensional honeycomb ferromagnet with sublattice-inequivalent Dzyaloshinskii-Moriya interactions. Using the Holstein-Primakoff transformation and the $T$-matrix approximation, we compute disorder-averaged Green's functions, spectral functions, and the thermal Hall conductivity ${\kappa }_{xy}$. Disorder scattering induces sublattice-selective resonant states and midgap states inside the magnon gap. At low temperatures, ${\kappa }_{xy}$ exhibits a sign reversal that is enhanced by increasing disorder concentration and sublattice occupation asymmetry, originating from the self-energy induced spectral broadening of the magnon bands.

We derive an analytical expression for the surface response function (SRF) of a large-area van der Waals heterostructure (vdWH) comprising an arbitrary sequence of atomically thin two-dimensional (2D) materials separated by insulating dielectric layers. The SRF is expressed as a continued fraction that incorporates the electronic conductivity components of each 2D material, accounting for both in-plane and out-of-plane (OOP) polarization induced by local macroscopic electric fields. Using generalized boundary conditions within the nonretarded limit, our approach aligns with established nanophotonic modeling of 2D materials. Our theory is primarily designed for electron energy loss spectroscopy (EELS) with nonpenetrating trajectories to probe the hybridization of plasmon modes in 2D materials with phonon modes in (potentially anisotropic) dielectric layers. Furthermore, our SRF is applicable to tip-based scanning near-field optical microscopy (s-SNOM). We illustrate potential applications for vdWHs containing one or two 2D materials and for a semi-infinite periodic superlattice. For the periodic superlattice, we derive explicit expressions for the surface plasmon mode and the bulk plasmon band, specifically highlighting the influence of OOP polarization of the constituent 2D materials.

We generalize the hyperbolic fracton model from the $\{5,4\}$ tessellation to generic {$p,q$} tessellations, and investigate its core properties—ground-state degeneracy, fracton mobility, and holographic correspondence—bringing to light a richer and more intricate structure than the original case. The ground-state degeneracy and subsystem symmetries are computed exactly through the inflation rule, but do not admit a simple, symmetric pattern. For small connectivity $q=3$, we find that the degeneracy is finite, either unique or fourfold. For the {4,4} square lattice as the flat limit of $q=4$, the degeneracy is well known to be subextensive. But for all other tessellations of $q>3$, the degeneracy becomes extensive, including for the {3,6} lattice on flat space, which maps onto the honeycomb color code. The fracton excitation number follows exponential-in-distance and algebraic-in-lattice-size growing patterns when moving outward and depends sensitively on the tessellation geometry, differing qualitatively from both type-I and type-II fracton models on flat lattices. Despite this increased complexity, the hallmark holographic features—subregion duality via Rindler reconstruction, the Ryu-Takayanagi formula for mutual information, and effective black hole entropy scaling with horizon area—remain valid. These results demonstrate that the holographic correspondence in fracton models persists in generic tessellations and provides a natural platform to explore more intricate subsystem symmetries and fracton physics.

We present a minimal, tunable many-body system of fermions coupled to quantum magnetic flux. The model is analytically diagonalizable and exhibits collective many-body phenomena, including an orbital Stoner instability and a Dicke-like quantum phase transition. The many-body interactions are mediated by zero-point fluctuations of a quantized magnetic flux whose oscillator mode remains in its ground state. In contrast to standard cavity quantum electrodynamics, where the dominant coupling is the electric-dipole coupling between matter and electric-field operators, here the quantized magnetic field of an LC resonator couples to the orbital angular momentum of the particles. Because the transition is driven by an orbital-current sector and the diamagnetic term is retained explicitly, the instability is not a conventional electric-dipole Dicke soft-mode transition. Adding a Josephson junction (JJ) to the linear LC circuit allows us to explore nonlinear flux-matter phases and sector-selective photon dressing in regimes relevant to circuit QED and mesoscopic rings. Furthermore, we consider tight-binding systems that exhibit a tunable nonlinearity representing a synthetic JJ without including an actual JJ in the circuit.

Dark exciton condensates offer a long-lived platform, yet controlling their density and spatial profile remains a central challenge. We develop a spatially resolved selectivity framework for driven-dissipative bright-dark condensates controlled by the bright-dark detuning ${\mathrm{\Delta }}_{\text{bd}}$. Within an open-condensate Gross-Pitaevskii framework with effective bright-branch injection and detailed-balance-consistent spin-flip rates, stationarity imposes a universal overlap-renormalized conversion constraint on the dark fraction, rather than on the bare population ratio alone. In the long-lived dark-branch regime this constraint reduces to $\mathcal{Q}\simeq exp({\mathrm{\Delta }}_{bd}/k_{B}T)$, while the bright component remains largely buffered by pump and radiative loss. Confinement then determines how the same constraint is realized in real space: soft traps yield ringlike dark accumulation, whereas hard-wall confinement produces boundary layers, radial quantization, and boundary-sensitive annular interfaces under weak pumping, with the corresponding radial branches dynamically selected or destabilized by the pump aperture. The extracted selectivity collapses across top-hat and Gaussian pumps, establishing a compact route to spatially resolved, dark-selective nonequilibrium regimes in van der Waals heterostructures.

We study theoretically a process of cooling electrons using a superconducting tunnel junction with a $\pi$ phase difference and a usual insulator or a ferroelectric in between, and an array of such junctions with ferroelectric layers in between. These setups have a complex structure of entropy due to nodal lines, where the density of states can be divergent or larger than for a free electron gas at a chemical potential level. We consider a small current running from the bath of electrons through the setup, where electrons have to have higher entropy, and thus remove heat from the bath.

Ferromagnetism in the single-orbital Hubbard model, which contains only local Coulomb repulsion and no explicit ferromagnetic exchange interactions, has been extensively studied. However, how the associated fluctuations influence the electronic properties near the transition remains a fundamental issue. Here, by applying the dynamical vertex approximation to single-orbital systems with a partially flat-band dispersion, we demonstrate that finite-correlation-length ferromagnetic fluctuations generate an emergent Luttinger surface and drive a Fermi-surface expansion reminiscent of exchange splitting, even without magnetic order. We further derive an analytical expression that reproduces these effects, clarifying the microscopic origin for fluctuation-driven exchange splitting in correlated electron systems.

Hybrid systems have attracted considerable attention due to their fundamental significance and potential technological applications in low-loss spin-based information processing and communication. Herein, we investigate temperature-dependent magnon-magnon coupling in a sputtered ${\mathrm{Co}}_{90}{\mathrm{Zr}}_{10}$/${\mathrm{Gd}}_{29}{\mathrm{Fe}}_{51}{\mathrm{Co}}_{20}$ (CoZr/GdFeCo) metallic heterostructure. Broadband ferromagnetic resonance reveals a clear avoided crossing between the uniform ferromagnetic resonance mode of CoZr and the perpendicular standing spin-wave mode of GdFeCo at room temperature. The minimum frequency separation (anticrossing gap) between the two hybridized branches is used to quantify the interlayer magnon-magnon coupling strength. Upon cooling, the coupling strength evolves nonmonotonically and reaches a maximum value of approximately 1 GHz near 200 K, close to the compensation region of GdFeCo. Linewidth analysis of the hybrid modes further reveals a distinct temperature-dependent spin-pumping contribution. The correlation between the linewidth-derived spin-pumping variation and the coupling strength suggests that the interfacial spin pumping, which is sensitive to the compensation behavior of GdFeCo, is involved in the modulation of the mode hybridization. Our experimental results provide insight into the temperature-dependent control of coupled magnon dynamics and suggest a promising route toward thermally responsive integrated magnonic devices.