We use large-scale density-matrix renormalization group simulations with bond dimensions up to $20000$ to determine the magnetization curves of spin-1 and spin-$\frac{3}{2}$ pyrochlore Heisenberg antiferromagnets. Both models exhibit a robust half-magnetization plateau. On the largest cubic cluster for which controlled energy extrapolations are feasible, containing 64 sites, we find that a plateau state with a 16-site magnetic unit cell (quadrupled structural unit cell) consistently has lower energy than competing ordering patterns for both spin lengths. This contrasts sharply with the prediction of the effective quantum dimer model and suggests a breakdown of the perturbative mechanism at the Heisenberg point. These results provide a nonperturbative characterization of field-induced phases in pyrochlore magnets and predictive guidance for spin-1 and spin-$\frac{3}{2}$ materials.

We investigate chiral superconductivity emerging from parent electronic states with non-uniform Berry curvature, motivated by recent experiments in rhombohedral graphene multilayers. Using the continuum ${\lambda }_N$-model—a tunable platform with independently controllable Berry curvature profiles—we solve the full Bardeen-Cooper-Schrieffer gap equation on a continuum Chern band beyond the weak-coupling limit. We find that a non-uniform Berry curvature of the parent band enriches the superconducting order parameter, leading to the formation of momentum-space vortices in the gap function away from high-symmetry points. By tuning the Berry curvature profile, we identify distinct regimes associated with vortex nucleation and vortex number saturation, and show that the nucleation of momentum-space vortices tends to lower the condensation energy. We then show analytically that the parent band Chern number constrains the number of momentum-space vortices that can nucleate in the gap—independent of details of the ${\lambda }_N$-model. We also provide a gauge-invariant formulation for computing the Bogoliubov–de Gennes (BdG) Berry curvature for continuum models, and find that it is determined by a momentum-space phase current. The winding of this current around vortices in the occupied region in turn determines the BdG Chern number. Finally, we discuss how thermal Hall measurements can be used to probe the formation of momentum-space vortices. Our results highlight the crucial role of Berry curvature in shaping chiral superconductivity, and offer guiding principles for its identification in systems such as rhombohedral graphene.

The coexistence of topological states with different dimensionalities in a single crystalline system offers a unique platform to study the interplay of distinct fermionic excitations. Here, integrating first-principles calculations with symmetry analysis, we propose the three-dimensional boron allotrope ${\text{CBT-B}}_{30}$ as an ideal, structurally stable candidate for exploring multidimensional topological physics. Benefiting from the practically negligible spin-orbit coupling of the light-element framework, ${\text{CBT-B}}_{30}$ operates as a pristine spinless topological semimetal. We show that the combined time-reversal and twofold screw symmetry ($\mathcal{T}{S}_{2z}$) enforces a robust two-dimensional nodal surface on the $k_z=\pi$ plane via a Kramers-like degeneracy. Concurrently, the system hosts a diverse set of zero-dimensional Weyl fermions—including an unconventional double-Weyl point with topological charge (Chern number) $C=-2$, conventional Type-I Weyl points (WPs; $\mathcal{C}=-1$), and completely tilted Type-II WPs ($\mathcal{C}=+1$)—emerging at the high-symmetry points $\mathrm{\Gamma }$ and $K$, as well as along the $H-K$ path, protected by $C_6$ and $C_3$ crystalline rotational symmetries. Crucially, the substantial momentum-space separation between the nodal surface and Weyl points allows for their unambiguous independent resolution. Calculations of the (100) surface states reveal distinct, nontrivial Fermi arcs connecting Weyl nodes of opposite chirality. This work establishes ${\text{CBT-B}}_{30}$ as a compelling material platform for investigating the physics of multidimensional hybrid topological fermions and their interplay.

Ferroelectric semiconducting oxides are promising platforms for energy-efficient devices based on polarization direction, such as ferroelectric random-access memories and field-effect transistors. Here, by exploiting a ferroelectric polarization-controlled $p\text{−}n$ junction established between a $p$-type ${\mathrm{Bi}}_2{\mathrm{FeCrO}}_6$ thin film and a Nb-doped ${\mathrm{SrTiO}}_3$ substrate, we demonstrate a nondestructive photovoltaic readout of the ferroelectric polarization direction. Using a conductive atomic force microscope coupled to a wavelength-tunable laser across the visible spectral range, it is shown that down-poled areas obtained by tip-induced domain writing generate a negligible short-circuit photocurrent, while up-poled areas produce large photocurrents with a clear dependence on illumination wavelength. An open-circuit voltage that increases logarithmically with laser power is also observed for the up-polarization state. These results establish a useful methodology for mapping ferroelectric photovoltaic effects and provide a promising perspective for future nonvolatile memory systems.

Macroscopic symmetry breaking governs many-body excitonic interactions and nonadiabatic carrier dynamics in the Janus ${\mathrm{OMoSiN}}_2$ monolayer. Many-body perturbation theory ($G_0{W}_0$–Bethe-Salpeter equation) and nonadiabatic molecular dynamics characterize this regime. A vacuum-level energy offset of approximately 2.5 eV reflects the strong built-in polarity and accompanies an orbital-specific quantum-confined Stark effect. The band-edge electron and hole centroids show an out-of-plane separation of Δ$z$ = 0.19 Å, and the static in-plane screening length is $r_0$ ≈ 34.8 Å. The direct-gap-referenced exciton binding energy reaches 2.24 eV and reflects the combined influence of reduced dimensionality and nonlocal screening, valley-dependent orbital character, and Janus-induced spatial asymmetry. For the relevant band-edge transitions, out-of-plane optical transitions are symmetry forbidden at the Γ and $K$ extrema. Away from these extrema, the out-of-plane response is finite but strongly suppressed, producing pronounced optical anisotropy. Time-domain carrier kinetics resolve a dynamic bottleneck. Polarity-driven spatial separation formally quenches the nonadiabatic coupling to 0.073 meV. This geometric blockade acts together with ultrafast quantum phase breaking. The resulting carrier lifetime is 409.5 ns. Highly polar two-dimensional architectures may therefore provide a platform for strongly bound excitons and decoherence-suppressed carrier dynamics.

We study the Emery model (three-band Hubbard model) for superconducting cuprates on three distinct ladderlike lattices that are supercells of the ${\mathrm{CuO}}_2$ plane and thus preserve the ratio of copper to oxygen atoms. Using the density-matrix renormalization group method we confirm that these Emery ladders are charge-transfer insulators for the hole concentration corresponding to undoped cuprates but become Luther-Emery liquids with enhanced pairing correlations upon doping. The preservation of the Cu to O ratio allows us to study the distribution of charges between these atoms in the Luther-Emery phase. We show that these Emery ladders can describe the relations between charge distribution, pairing strength, and interactions that have been observed in the Emery model on two-dimensional clusters and in experiments.

Cascaded emission from the biexciton state of a quantum dot results in polarization entangled photon pairs. Cavity enhancement of the direct two-photon emission channel bypasses the dominant source of decoherence in this system, namely the fine-structure splitting of the exciton levels. Here, we investigate the remaining non-Markovian phonon-induced decoherence using the numerically exact uniTEMPO algorithm. We compute the degree of entanglement of photon pairs generated by pulsed two-photon resonant excitation and find surprisingly good agreement between the numerically exact results and those calculated using the approximate polaron master equation method, permitting an efficient exploration of trends across system parameters.

Kinetic constraints are generally expected to slow down dynamics in many-body systems, obstructing or even completely suppressing transport of conserved charges. Here, we show how gauge theories can defy this wisdom by yielding constrained models with faster-than-diffusive dynamics. We first show how, upon integrating out the gauge fields, one-dimensional U(1) lattice gauge theories are exactly mapped onto XX models with nonlocal constraints. This class of kinetically constrained models interpolates between free theories and highly constrained local fermionic models. We find that energy transport is superdiffusive over a broad parameter regime. Even more drastically, spin transport exhibits ballistic behavior, albeit with anomalous finite-volume properties as a consequence of gauge invariance. Our findings are relevant to current efforts in quantum simulations of gauge-theory dynamics and anomalous hydrodynamics in closed quantum many-body systems.

Local observables and their translationally invariant counterparts are generally thought to provide the same predictions for experiments. While this equivalence holds for expectation values in clean systems (up to finite-size effects), it is often assumed to extend to correlation functions, where it need not hold. We examine this assumption from the perspective of the eigenstate thermalization hypothesis. Specifically, we explore the spectral functions of local and translationally invariant observables in the spin-1 tilted-field Ising chain with periodic and open boundary conditions. We identify the contexts in which these observables and boundary conditions differ and those in which they are interchangeable. We unveil an off-diagonal eigenstate thermalization in translationally invariant systems for matrix elements between energy eigenstates with different quasimomenta.

We investigate localization phenomena and exact mobility edges in a quasiperiodic Aharonov-Bohm chain, where the 1D canonical diagonal and off-diagonal Aubry-André-Harper models are laterally coupled to an auxiliary sublattice threaded by a synthetic magnetic flux. By analytically computing the Lyapunov exponent via Avila's global theory of one-frequency Schrödinger operators, we derive exact expressions for mobility edges. In the diagonal limit, the coupling to the auxiliary sublattice generates hyperbolic mobility edges that exhibit a sign-changing divergence and can be continuously tuned by the magnetic flux. In the off-diagonal regime, the interference between quasiperiodic hopping and indirect tunneling through the auxiliary sublattice gives rise to exact anomalous mobility edges that separate critical and extended states. Critical states and anomalous mobility edges emerge even in the absence of incommensurately distributed zeros in the hopping modulation, a behavior distinct from that of conventional off-diagonal models. Our results establish a rigorous theoretical framework for engineering controllable mobility edges, with the synthetic flux providing a tunable experimental knob that paves the way for realizations in platforms such as superconducting quantum circuits and photonic waveguides.

We derive the first-principles Ehrenfest molecular dynamics describing nonadiabatic processes with the inclusion of the nuclear-velocity-dependent phases (also known as electron-translation factors) on the atomic orbital basis. These phases, appearing when nuclei are treated dynamically, affect effective Hamiltonians constructed from localized orbitals. In this work, we focus on the effects on the first-principles pseudopotential Hamiltonian for both the norm-conserving and ultrasoft cases, derived within the projector augmented wave method framework. Peierls-like phases depending on the nuclear velocities appear in the nonlocal part of the potential, while additional nuclear velocity and acceleration-dependent corrections appear in the ultrasoft pseudopotential case. The use of the velocity-including atomic orbital basis enables a Galilean-invariant description of the nonadiabatic Ehrenfest molecular dynamics, removing spurious nonadiabatic couplings that arise from neglecting the nuclear velocity phases in the atomic orbitals.

Crystalline solids exhibiting glasslike (ultralow) thermal conductivity have received substantial attention, owing to their significance in fundamental physics and practical applications like thermal insulation and thermoelectric devices. Conventionally, achieving this desirable, intrinsically thermal insulating behavior requires heavy atoms and complex lattice structures, limiting the search space for material design. Here, we reported the coexistence of anomalous positive temperature dependence alongside a moderate conductivity magnitude in hexagonal α-graphyne, despite its remarkably light atoms and simple lattice. Using first-principles anharmonic lattice dynamics and the unified thermal transport theory, we reveal that, at room temperature, the predicted thermal conductivity contributed by wavelike phonons (${\kappa }_{\mathrm{c}}$) is 5.7 W/mK, being comparable to the 8.6 W/mK contributed by particlelike phonons (${\kappa }_{\mathrm{p}}$), deviating from the established transport understandings in α-graphyne based on particlelike phonon transport. As temperature increases from 400 to 800 K, the ${\kappa }_{\mathrm{c}}$ component dominates thermal transport, driving an anomalous increase in total thermal conductivity (${\kappa }_{\mathrm{l}}={\kappa }_{\mathrm{c}}+{\kappa }_{\mathrm{p}}$) with temperature. Further analyses reveal that, driven by strong four-phonon anharmonicity, the high scattering rates of phonon modes near 13 and 62 THz bridge the frequency gap between nondegenerate eigenstates (with large frequency discrepancy), enabling robust interband tunneling. This work highlights the importance of wavelike tunneling and quartic anharmonicity in describing thermal transport in α-graphyne and opens a new avenue for overcoming conventional thermal conductivity barriers.

The phenomenon of spin wave (SW) freezing occurs in the Damon-Eshbach mode in thin film magnetic systems, when SW phase and group velocities both go to zero, and the wave ceases to oscillate and move, preserving its shape as a domain structure pattern. This effect is related to the spin reorientation transition, where the magnetization configuration changes between the homogeneous in-plane state and domain structure with the out-of-plane magnetization component state. Here we study the SW freezing effect in ${[\mathrm{Re}/\mathrm{Co}/\mathrm{Pt}]}_{20}$ magnetic multilayers, induced by varying the in-plane external magnetic field. The studies were performed on nanostructures with the quality factor $Q$ (ratio of uniaxial anisotropy to demagnetization energies) greater and smaller than one. Domain structures with an out-of-plane magnetization component were observed in these multilayers. The critical field, visible as the saturation field $H_{\mathrm{s}}^{\left|\right|}$ in the parallel static magnetization curve measured by superconducting quantum interference device (SQUID), is also manifested in the field-dependent vector-network-analyzer ferromagnetic resonance (VNA-FMR) experiment, which measures the homogeneous magnetization oscillations. Brillouin Light Scattering (BLS) spectra, recorded for several values of wave vectors and several field values, probed the field-evolution of the dispersion relation. Micromagnetic simulations allow one to obtain a full dispersion, in good agreement with VNA-FMR and BLS results. Around $H_{\mathrm{s}}^{\left|\right|}$ the simulated dispersion relations approach the conditions for SW freezing. Below $H_{\mathrm{s}}^{\left|\right|}$ low- and high-frequency VNA-FMR modes are related to magnetization oscillations inside domain walls and within domains, respectively. The experimental results of static and dynamic behavior, together with micromagnetic simulations, create an overall consistent picture of the investigated multilayers.

The 1/9 magnetization plateau has recently been observed in the spin-1/2 kagome Heisenberg antiferromagnet (KHA) ${\mathrm{YCu}}_3{\left(\mathrm{OH}\right)}_6{\mathrm{Br}}_2\left[{\mathrm{Br}}_{1-y}{\left(\mathrm{OH}\right)}_y\right]$ (YCOB), a promising quantum spin liquid (QSL) candidate. However, the 1/9 plateau has so far been reported only in YCOB, and its microscopic origin and low-energy nature remain under debate. In this study, we investigate the magnetic properties of the chlorine-substituted series ${\mathrm{YCu}}_3{\left(\mathrm{OH}\right)}_6\left[{\left({\mathrm{Cl}}_x{\mathrm{Br}}_{1-x}\right)}_{3-y}{\left(\mathrm{OH}\right)}_y\right]$ (YCOB-Cl) and track the evolution of the 1/9 magnetization plateau across the doping series. We observe clear signatures of the 1/9 plateau at multiple nominal Cl concentrations. The temperature dependence of the plateau response evolves systematically with increasing $x$, consistent with a progressive suppression of low-energy spectral weight and the emergence of a possible effective gap scale. Complementary magnetic torque measurements further show that the magnetic oscillations accompanying the plateau are present only in the $x=0$ sample, indicating that chemical substitution strongly affects the low-energy states associated with the plateau. Taken together, our results establish YCOB-Cl as a tunable platform for exploring how chemical disorder and modified exchange networks reshape the 1/9 plateau and its associated anomalous magnetic responses.

Low-dimensional systems with intrinsic magnetism have attracted significant attention because of their intriguing physical properties and potential applications in spintronic devices. Here, we present a systematic first-principles study of the magnetic properties of bulk, monolayer, bilayer, and trilayer ${\mathrm{FePd}}_2{\mathrm{Te}}_2$. For bulk ${\mathrm{FePd}}_2{\mathrm{Te}}_2$, including longitudinal spin fluctuations yields a calculated $T_c$ of about 188 K, in good agreement with experiment. Upon reducing the dimensionality, ${\mathrm{FePd}}_2{\mathrm{Te}}_2$ exhibits a clear thickness dependence in both the magnitude and the easy-axis direction of the magnetic anisotropy energy (MAE). Meanwhile, the magnetic order evolves from ferromagnetic (FM) in the bilayer and trilayer ($T_c=138$ and 186 K, respectively) to interchain antiferromagnetic (AFM) in the monolayer ($T_n=72\mathrm{K}$). Moreover, strain engineering provides an efficient route to tune the magnetism of monolayer and few-layer ${\mathrm{FePd}}_2{\mathrm{Te}}_2$ by strongly modulating the exchange couplings, enhancing the MAE up to 2.00 meV/Fe in the monolayer, and driving AFM-to-FM transitions in the monolayer and bilayer. As a result, the magnetic transition temperatures can be increased to 194 K in the monolayer, 188 K in the bilayer, and 207 K in the trilayer. Our results highlight the key role of weak interchain couplings in ${\mathrm{FePd}}_2{\mathrm{Te}}_2$, which govern both the magnetic ground states and the magnetic transition temperatures.

Using exact diagonalization and variational tensor network methods, we study ground states near the ferromagnetic $\mathrm{SU}\left(3\right)$ point at $\theta =5\pi /4$ in the spin-1 bilinear-biquadratic model from a finite-size approach. In particular, two types of scale-invariant states, scale-invariant states with type-B Goldstone modes and conformal-invariant states, are involved. Universal finite-size entanglement entropy scaling for the two distinct types of scale-invariant states, which exhibit boundary dependence in conformal-invariant states and boundary independence arising from emergent lattice-permutation symmetry in scale-invariant states with type-B Goldstone modes, enable a clarification of the physics in the vicinity of the ferromagnetic $\mathrm{SU}\left(3\right)$ point. According to the results from exact diagonalization with system size up to $L=16$, entanglement entropy in the vicinity of the point $\theta =5\pi /4$ presents a universal finite-size scaling for scale-invariant states with two type-B Goldstone modes to high precision, independent of the boundary conditions, as a result of an emergent lattice-permutation symmetry in the scale-invariant states. Meanwhile, from both an exact diagonalization method and a variational tensor network method, a unique “conformal-invariant point” is identified near $\theta =5\pi /4$ with central charge $c=2$ under both periodic and open boundary conditions, moving toward the point $\theta =5\pi /4$ as $L$ increases, suggesting a direct ferromagnetic-to-dimerized phase transition in the thermodynamic limit. The fractal nature at the $\mathrm{SU}\left(3\right)$ point is confirmed indirectly by the nearby scale-invariant-like states, following the spontaneous breaking of $\mathrm{SU}\left(3\right)$ symmetry to $\mathrm{SU}\left(2\right)\times \mathrm{U}\left(1\right)$ symmetry, resulting in two type-B Goldstone modes. Such scale-invariant-like states in the vicinity of points relating to type-B Goldstone modes may exist more generally in other models, offering an indirect approach to detecting type-B Goldstone modes.

Polarization-analyzed small-angle neutron scattering (PASANS) methods are used to determine the spin arrangements and experimental length scales of magnetic correlations in ordered three-dimensional assemblies of $\sim 7.6$ nm diameter chemically homogeneous manganese ferrite nanoparticles. While the perpendicular magnetic scattering at remanence mostly follows single particle behavior at high temperature, the scattering deviates upon cooling the particles, growing maximally at intermediate temperatures ($\approx$50–100 K) with intermediate field values also displaying canted magnetic structures. The data are fit with a sphere-based mass fractal model and are interpreted further via a micromagnetic simulation approach. The unusual temperature and field dependencies are explained in terms of a delicate balance between magnetic anisotropy and demagnetization. These results highlight the ability of PASANS to extract key features in nanoscale systems and the importance of correlating micromagnetic simulations.

Altermagnets represent a recently identified class of magnetic materials that combine features of both ferromagnets and antiferromagnets. While they have compensated magnetic order, as in antiferromagnets, they exhibit time-reversal broken and spin-polarized bands as in ferromagnets, leading to unconventional spin excitations. Although the electronic properties of altermagnets have been intensively studied, revealing spin-split band structure, the same is not true for their magnonic excitations. One altermagnetic material of great recent interest is CrSb that has a metallic character with perfectly compensated Ising spins below a Néel temperature $T_N\approx 735\mathrm{K}$. The magnon dispersion relations in CrSb have been recently measured by inelastic neutron scattering (INS) techniques over various directions of the Brillouin zone (BZ), revealing a chiral magnon splitting for wave vectors along a low-symmetry direction. Here we present an analytical quantum spin-wave theory for CrSb considering five exchange interactions and a uniaxial magnetic anisotropy that gives analytical expressions for the magnon dispersion relations for wave vectors along main BZ axes. These expressions give simple equations relating the interaction parameters with the values of the measured magnon energies at some symmetry points of the Brillouin zone. Within the uncertainties, the calculated parameters agree well with the ones obtained by fitting the theory to the whole INS data for CrSb.