Computational discovery of magnetic materials remains challenging because magnetism arises from the competition between kinetic energy and Coulomb interaction that is often beyond the reach of standard electronic-structure methods. Here we tackle this challenge by directly solving the many-electron Schrödinger equation with a neural-network variational Monte Carlo technique, which provides a highly expressive variational wave function for strongly correlated systems. Applying this technique to transition metal dichalcogenide moiré semicondutors, we predict itinerant ferromagnetism in ${\mathrm{WSe}}_2$/${\mathrm{WS}}_2$ and an antiferromagnetic insulator in twisted $\mathrm{\Gamma }$-valley homobilayer, using the same neural network without any physics input beyond the microscopic Hamiltonian. Crucially, both types of magnetic states are obtained from a single calculation within the $S_z=0$ sector, removing the need to compute and compare multiple $S_z$ sectors. This significantly reduces computational cost and paves the way for faster and more reliable magnetic material design.

We show that the gate-to-channel capacitance in magnetically doped topological insulators allows access to information on bulk conductivity. We found that unlike resistivity, capacitance directly reveals the presence of two different types of bulk insulators. Furthermore, the capacitance captures the different topology of the two insulators. We also found that deep on a quantized plateau, changes in the low value conductivity of the bulk remain detectable via capacitance. We conclude that the combination of capacitance and transport in Hall bars enables a comprehensive investigation of the interplay of bulk and edge effects in magnetically doped topological insulators.

Enhancing the many-body gap of a fractional state is crucial for realizing robust fractional excitations. For fractional Chern insulators, existing studies suggest that making flat Chern bands closely resemble the lowest Landau level (LLL) seems to maximize the excitation gap, providing an apparently optimal platform. In this work, we demonstrate that deforming away from the LLL limit can, in fact, produce substantially larger fractional quantum Hall gaps. Using moiré flat bands with strongly non-Landau-level wave functions, we show that the gap can exceed that of the LLL by more than two orders of magnitude for short-range interactions and by factors of two to three for long-range interactions. This enhancement is generic across Abelian fractional Chern insulator states and follows a universal enhancement factor within each hierarchy. In the Landau-level framework, we identify the amplification of pseudopotentials as the microscopic origin of the observed enhancement. More generally, in a Chern band system where the pseudopotential decomposition is not well defined, we find a sharp scaling distinction: in the strongly screened regime, the $\nu =1/3$ gap scales cubically with gate distance $d_s$ in the LLL and vortexable Chern bands, but linearly in higher-vortexable Chern bands. The activation of this leading $O\left(d_s\right)$ term by deviating from ideal quantum geometry is the key origin of the gap enhancement, and this criterion remains meaningful even without rotational symmetry. We further examined non-Abelian states and found that within finite-size resolution, this wave-function construction method can also be used to manipulate and enhance the gap for certain interaction parameters. We further discuss experimental implications of our findings in twisted bilayer ${\mathrm{MoTe}}_2$.

We study an effective low-energy Kondo model on the triangular lattice in which itinerant electrons occupy a valence pocket at $\mathrm{\Gamma }$ and three conduction pockets at the $M$ points of the Brillouin zone. This construction has a Fermi-surface nesting structure that favors triple-$Q$ magnetic order while only assuming the low-energy band-structure. Treating the local moments as classical spins on a four-sublattice magnetic unit cell, we find extended regions of noncoplanar order, including tetrahedral and related canted tetrahedral states, in addition to ferromagnetic and coplanar phases. The chiral phases remain stable over a broad range of interpocket Kondo couplings and persist in the presence of an external magnetic field. For certain chiral orders, the electronic bands can become gapped and host a quantum anomalous Hall state with ${\sigma }_{xy}=4e^2/h$. These results show that chiral magnetism and a quantized anomalous Hall effect on the triangular lattice do not rely on a specific tight-binding band structure, but can arise more generally from low-energy nested pockets at $\mathrm{\Gamma }$ and $M$.

We study terahertz field-driven second order nonlinear electron transport phenomena, including the nonlinear Hall effect (NLHE), in two-dimensional tellurene flakes. The dc current excited by linearly polarized terahertz (THz) radiation in Hall bar samples is investigated in directions both along and perpendicular to the $c$ axis of tellurene. As expected for second order transport phenomena, the current scales as the square of the in-plane electric field of the radiation $\mathit{E}$, and depends on its orientation. The current results from a combination of three contributions, including the NLHE, the Nonlinear Longitudinal (NLL) and Nonlinear Diagonal (NLD) currents. We established the equivalence between NLH, NLL, and NLD transport currents and Linear photogalvanic effect (LPGE) contributions induced by the absorption of linearly polarized and unpolarized THz radiation. All contributions can be controlled by a gate voltage and have opposite signs for electron and hole conductivity. The magnitude of the current increases drastically when the samples are cooled from room temperature to 4.2 K. It also increases with decreasing radiation frequency. These results are well described by the developed phenomenological and microscopic theories. We show that the THz radiation-induced electric current originates from microscopic mechanisms such as skew scattering, side jump, and the Berry curvature dipole.

We demonstrate an electrically driven mechanism for controlling interfacial magnetic exchange and spin-polarized transport in a Co/Nb-doped ${\mathrm{HfO}}_2/\mathrm{Co}$ multiferroic tunnel junction. Using first-principles density functional theory and quantum transport calculations, we show that the ferroelectric polarization direction modulates the local orbital symmetry and hybridization pathways at the Nb–O–Hf interfaces, thereby switching the magnetic coupling between Nb and Hf from antiferromagnetic to ferromagnetic. In the antiparallel magnetic configuration, this orbital-selective control reverses the dominant spin channel and produces nearly complete, electrically switchable spin polarization in the zero-bias transmission over a broad energy window around the Fermi level. Our findings reveal the key role of polarization-driven orbital engineering in achieving deterministic, electrically tunable spin currents, providing another pathway for designing high-performance spintronic devices.

We study the local and nonlocal charge transport properties of a three-terminal nanostructure, consisting of the correlated quantum dot embedded between two metallic electrodes and superconductor. Using the linear response theory, we analyze interplay of the induced on-dot pairing with the correlation effects, inspecting their influence on the conductance and thermopower. Our calculations predict negative values of the nonlocal conductance and reversal of the Seebeck coefficient when the quantum dot ground state is represented by the Bardeen–Cooper–Schrieffer (BCS)-type singlet configuration. These phenomena are realized when the subgap charge transport is predominantly contributed by the crossed Andreev scattering. In contrast, on the doublet side, we obtain signatures for the Kondo effect manifested by the low-temperature enhancement of the charge conductance and clearly evident in the thermopower. Such temperature-dependent local and nonlocal transport properties can unambiguously identify the specific configuration of the correlated quantum dot and reveal the rich physics emerging in the doublet-to-singlet crossover region.

Symmetry offers a useful approach to unfold the intertwined degrees of freedom. Thus, it paves the way to resolving coexisting quantum orders into distinct symmetry sectors. Motivated by the recent observation of superconductivity (SC) in nanoflaked ${\mathrm{IrTe}}_2$, we investigate the SC in the strain-stabilized two-dimensional (2D) limit of ${\mathrm{IrTe}}_2$ by combining density functional theory with mean-field solution of the spin-fluctuation–mediated pairing interaction on a symmetry-constrained $\mathbf{k}·\mathbf{p}$ model. The spin-orbit–coupled band structure shows $\mathrm{\Gamma }$-centered Fermi sheets with existence of band-selective Rashba-like (in-plane) and Ising-like (out-of-plane) SC in the same compound. Remarkably, the SC gaps are odd in spin, orbital, and momentum channels despite the presence of global inversion symmetry. Fermi surface topologies and little-group symmetry enforce distinct irreducible representations to the Rashba and Ising channels, forbidding their mixing. Our findings open a symmetry-based route to multichannel SC in 2D transition-metal dichalcogenides with unique functionalities.

Layered transition-metal dichalcogenides can host multiple crystal structures that are closely spaced in free energy, giving rise to rich electronic diversity under modest external perturbations. Molybdenum ditelluride ($\mathrm{Mo}{\mathrm{Te}}_2$) is a paradigmatic example, in which semiconducting and semimetallic polymorphs closely compete energetically. Here we investigate how hydrostatic compression reshapes electronic transport in bulk $2H\text{−}\mathrm{Mo}{\mathrm{Te}}_2$. At ambient pressure, resistivity and magnetotransport measurements establish a robust insulating ground state governed by strong localization. Upon compression to pressure up to 15.6 GPa, transport evolves continuously from the $2H$ semiconducting regime into an electronic response characterized by large, nonsaturating magnetoresistance and low-temperature quantum-interference effects reminiscent of those reported in semimetallic $1T^{\prime }/\mathrm{Td} \mathrm{Mo}{\mathrm{Te}}_2$. First-principles calculations including spin-orbit coupling reveal a progressive pressure-driven reconstruction of the electronic structure, whereby the indirect band gap narrows and collapses into a semimetallic electronic manifold. Together, these results identify a pressure-tuned localization-to-coherence crossover as the organizing principle of transport in bulk $2H\text{−}\mathrm{Mo}{\mathrm{Te}}_2$, linking disorder-controlled hopping at ambient pressure to quantum-coherent semimetalliclike transport at high pressure. These results demonstrate how lattice compression enables controlled access to competing electronic regimes in layered tellurides and highlight external tuning as a route toward spin-orbit-coupled semimetallic transport states.

We show that momentum-space tensor monopoles corresponding to nontrivial vector bundle generalizations, known as bundle gerbes, can be realized in bands of three-dimensional topological matter with nontrivial Hopf invariants. We provide a universal construction of tensor Berry connections in these topological phases, demonstrating how obstructions therein lead to $\mathbb{Z}$-quantized bulk magnetoelectric and nonlinear optical phenomena in the presence of spacetime inversion ($\mathcal{PT}$) symmetry. We then pinpoint that these quantum effects are supported by intraband and interband torsion leading to nontrivial Dixmier-Douady classes in most known Hopf phases and in more general topological insulators realizing gerbe invariants falling beyond the tenfold classification of topological phases of matter. We furthermore provide an interacting generalization upon introducing many-body gerbe invariants by employing twisted boundary conditions. This opens an avenue to study gerbe invariants realized through higher-dimensional charge fractionalizations that can be electromagnetically probed.

Correlated emission of light offers a potential avenue for entanglement generation between atomic spins, with potential application for sensing and quantum memory. In this Letter, we investigate the conditions for the correlated emission by color centers into an electronic bath of conduction electrons. Unlike emission into bosonic modes, electrons can absorb energy via two-particle processes across a large range of length scales. We find that two length scales are particularly relevant in a clean system: one set by the Fermi velocity and the frequency of the color centers $v_F/\mathrm{\Delta }$, and the other set by the Fermi wavelength ${\lambda }_F\ll v_F/\mathrm{\Delta }$. Subradiance requires emitters to be spaced at a distance closer than the Fermi wavelength, while superradiance requires spacing less than $\sqrt{{\lambda }_F{v}_F/\mathrm{\Delta }}$, so long as the emitters are initialized with coherence. We show that the emitted current burst has a spiral form, and we discuss the experimental possibility to observe correlated dissipation by color-center qubits coupled to electronic environments.

We investigate spin-wave modes in confined ferromagnetic resonators with spherical and cylindrical geometries across the exchange-dominated, dipole-exchange, and dipolar interaction regimes. Starting from the linearized Landau-Lifshitz-Gilbert equation, we show that the projection of the total angular momentum and mirror parity are conserved quantities in the problem of axially symmetric resonators. These symmetries provide a natural classification of spin-wave modes and explain the degeneracy of exchange modes, as well as its lifting by dipolar interactions. Numerical analysis shows that the nonlocal dipolar interaction removes the exchange degeneracy and hybridizes modes, leading to avoided crossings between modes that belong to the same symmetry sector. To describe this behavior, we develop a coupled-mode theory formulated directly in terms of dynamical magnetization, which reduces the dipole-exchange problem to a finite system of interacting modes. The resulting framework provides a unified description of spin-wave spectra in confined magnetic particles from the exchange limit to the dipolar regime.

${\mathrm{NaRuO}}_2$ forms a delafossitelike structure that contains triangular sublattices of edge-sharing ${\mathrm{RuO}}_6$ octahedra. It shows no evidence of magnetic order down to 100 mK and persistent spin fluctuations, suggestive of a quantum disordered magnetic ground state. In order to characterize the physical regime from which this disordered state arises, we use resonant inelastic x-ray scattering (RIXS) and x-ray absorption spectroscopy (XAS) at the $\mathrm{Ru}\text{−}{L}_{2,3}$ edge, along with pulsed high-field magnetization to characterize both the local electronic structure and the magnetic interactions. We infer significant spin-orbit coupling from XAS measurements. With RIXS, we observe intraorbital excitations, which are damped due to the near itinerancy of the band and suggestive of strong charge fluctuations. Corroborated by fits of the high-field magnetization to a random singlet model, we propose a picture of a nearly itinerant system with strong magnetic and charge fluctuations that destabilize long-range magnetic order.

Compensated ferrimagnets, which break sublattice and time-reversal symmetries in the ground state, exhibit an isotropic ferromagnetlike spin splitting despite a vanishing net magnetization, in contrast to altermagnets with momentum-dependent spin splitting. We investigate how isotropic spin splitting manifests in spin transport by analyzing the spin Seebeck effect and spin pumping in a junction between a compensated ferrimagnet and a normal metal. We show that compensated ferrimagnets generate a sizable spin Seebeck signal, with a sign that can be reversed by switching between the two Néel states. Furthermore, we demonstrate that spin pumping exhibits a Néel-state-dependent resonance splitting, which is absent in conventional antiferromagnets. These results identify spin pumping as a natural readout mechanism for compensated ferrimagnets and establish them as promising magnetization-free building blocks for spintronic memory devices.

Coherent phonons are phase-locked lattice vibrations that provide a sensitive probe of nonequilibrium dynamics in materials. Existing first-principles equation-of-motion (EOM) approaches have successfully described coherent phonons in metals and semimetals, but their extension to semiconductors requires treating the long-lived electron-hole plasma created by above-gap excitation. Here we extend the first-principles EOM framework to photoexcited semiconductors by incorporating the residual plasma force that shifts the lattice equilibrium together with the plasma-induced renormalization of the electronic structure. For monolayer ${\mathrm{MoTe}}_2$, the calculated carrier-density-dependent Te displacement agrees with constrained density-functional perturbation theory only when the renormalized band structure is included. We then show that increasing the photoexcited carrier density enhances both the initial total force and the plasma-shifted equilibrium position of the $A_{1g}$ mode, producing larger coherent lattice oscillations. This density-controlled response appears in both the atomic displacement and the coherent-phonon-induced band renormalization, providing complementary signatures for ultrafast reflectivity and time- and angle-resolved photoemission spectroscopy.

We report a temperature-dependent investigation of orthoferrite ${\mathrm{TbFeO}}_3$ using x-ray diffraction, dc magnetization, and Raman scattering, complemented by room-temperature x-ray photoelectron spectroscopy. X-ray diffraction reveals negative thermal expansion over 5–300 K, with a small but systematic increase in unit-cell volume upon cooling in the absence of any structural phase transition. Raman scattering measurements identify the Raman-active phonon modes and show clear deviations from the conventional Klemens anharmonic decay model, particularly in phonon frequencies, indicating the presence of spin-phonon coupling. Two modes of $A_g$ and $B_{1g}$ symmetry exhibit a crossover from Gaussian-dominated line shapes at low temperatures to mixed Gaussian-Lorentzian profiles at higher temperatures, reflecting a transition from inhomogeneous broadening to lifetime-driven dynamics. High-energy Raman spectra reveal two-magnon excitations associated with the Fe sublattice, consistent with linear spin-wave theory, whose spectral weight shows only weak temperature dependence. In addition, a broad Raman mode emerging below $\sim 175\mathrm{K}$ exhibits an onsetlike temperature evolution and coincides with the occurrence of phonon anomalies, while no corresponding strong anomaly is observed in the two-magnon response. Taken together, these results establish ${\mathrm{TbFeO}}_3$ as a system with pronounced interplay among lattice dynamics, spin correlations, and emergent local magnetic-lattice anomalies.

Boosting superconductivity by metallic reservoirs is the essence of Kivelson's bilayer proposal. One layer provides pairing to the electrons, while the weakly coupled metal provides additional phase coherence to those pairs by mediating extended-range pair-pair coupling. Demonstrating significant and unambiguous performance gains with strong-coupling methods for such setups had been difficult. In the present work, we study these systems doped away from half filling, corresponding to a partially spin-polarized 1D Anderson or Kondo lattice. We show that this breaks the coexistence of dominant superconducting and density-density correlations decisively in favor or the former. Consequently, we provide evidence that in this doped regime, superconducting near-long-range order is not precluded by a small charge gap in the thermodynamic limit, as we have recently shown to be the case at half filling. We study the complex manner in which the enhancement of superconductivity in the pairing layer depends on the parameters of the metal, and especially that both pairing-limited and stiffness-limited regimes may appear in these systems. In addition to superconducting bilayers, our results are relevant, via a particle-hole transformation, for heavy-fermion Kondo-lattice materials in magnetic fields, as we provide previously lacking insight on the competition between antiferromagnetic and easy-plane magnetism, as well as a route for comprehensive indirect tests of Kivelson's bilayer proposal well beyond previous capabilities.