We study the spin excitations in the frustrated coplanar ${120}^{\circ }$ ground state of the triangular-lattice Heisenberg antiferromagnet and demonstrate that they carry a magnetic moment perpendicular to the plane in which the spins order, despite the ground-state sublattice moments having no out-of-plane component. The symmetry of the momentum dependence of the magnetic moment and energy of the magnons renders the system an odd-parity $f$-wave magnet. Extending this model to a stack of antiferromagnetically coupled triangular layers provides a realization of magnons in a three-dimensional $f$-wave anti-altermagnet. We show that nonlinear thermal transport effects of magnons, such as Edelstein and spin-splitter effects, provide clear experimental signatures of magnons in $f$-wave anti-altermagnets.

We study the spatially dispersive conductivity of a two-dimensional noncentrosymmetric superconductor, demonstrating that it acquires a nonreciprocal, odd-in-wave-vector component from fluctuation-induced Cooper pairs above the critical temperature $T_c$. Utilizing time-dependent Ginzburg-Landau theory generalized to include particle-hole asymmetry and the cubic Lifshitz invariant of trigonal superconductors, we compute the Aslamazov-Larkin contribution to the gyrotropic conductivity in closed form, including its complete frequency dependence. The dissipative part describes nonreciprocal directional dichroism: it is odd in frequency and displays a nonmonotonic dependence, peaking at frequencies comparable to the decay rate of fluctuating Cooper pairs. Its Kramers-Kronig dual component describes gyrotropic birefringence, which remains finite in the static limit and is strongly enhanced as the temperature approaches $T_c$, as long as the probe frequency stays below the pair decay rate. Both effects require simultaneously broken inversion and time-reversal symmetries, are dependent on particle-hole asymmetry in close analogy to the fluctuation Hall effect, and trace to the same asymmetric Cooper-pair dispersion responsible for the superconducting diode effect and the giant magnetochiral anisotropy observed near $T_c$. In this regime this critical enhancement dominates over the smooth normal-state gyrotropy, which we evaluate for the same band model as a baseline. Finally, we frame our analysis within the context of gated transition metal dichalcogenides like ${\mathrm{MoS}}_2$, discussing the implications for probing superconducting dynamics through nitrogen-vacancy-center quantum noise spectroscopy.

The magnetic penetration depth, $\lambda$, is a fundamental parameter of the superconducting state and is commonly determined from precision measurements of the magnetic susceptibility, $\chi$, in the Meissner state. However, extracting $\lambda$ from such measurements requires an accurate treatment of geometry-dependent demagnetization effects, for which analytic results are only available in a limited number of cases. Here we present a finite-element analysis of the magnetic response of three-dimensional superconducting spheroids and cylinders with finite penetration depth. By calculating the magnetic moment and susceptibility, $\chi \left(\lambda \right)$, over a wide range of aspect ratios, we quantify the shape-dependent Meissner response and extract effective demagnetization factors in the $\lambda \to 0$ limit. For small but finite $\lambda$, we further determine effective sample dimensions from the initial variation of $\chi \left(\lambda \right)$ and propose an improved analytical expression for these. Our results provide a high-precision procedure for determining $\lambda$ from volume-exclusion based susceptibility measurements and should be directly applicable to the characterization of superconducting materials.

Exciton condensation, a collective phase-coherent state of bound electron-hole pairs, is expected to enable phenomena such as dissipationless counterflow and novel broken-symmetry states but has remained difficult to realize in zero magnetic field. In semiconductors, exciton condensation requires the exciton binding energy to exceed the band gap, where the binding energy derives from Coulomb attraction between electrons and holes. The absence of unambiguous observations indicates either that the binding energy is insufficient in most candidate systems or that, even if sufficient, the critical temperature is too low to permit clear experimental detection. To enhance the binding energy—and hence the critical temperature—we propose a different control parameter: an in-plane electric field. Being inversion odd, the electric field hybridizes low-lying excitons of opposite parity (e.g., $s$- and $p$-wave excitons), and one of the resulting hybrid modes is lower in energy via level repulsion. The in-plane electric field therefore enhances the effective binding energy, providing a different route to stabilizing exciton condensation. We illustrate the mechanism in biased bilayer graphene using a microscopic Bethe-Salpeter treatment and identify the resulting phase boundary for electric-field-induced condensation. We further compute properties of the electric-field-assisted condensate phase and identify several experimental signatures.

Tantalum (Ta) is a body-centered cubic (bcc) metal at ambient conditions and up to its melting point along the principal Hugoniot; however, direct melting temperature measurements are limited. We have developed a technique to measure the surface thermal state of a thin Ta coating shock-released onto a transparent window by combining reflectivity, velocimetry, and pyrometry. Ta is initially shocked into the solid-liquid coexistence and liquid phases, and its shock-released and subsequent reverberated temperature-pressure states are measured. Simultaneous x-ray diffraction is performed on the reverberated state, and the bcc phase is observed off-Hugoniot at 142 GPa. Shock-released and reverberated states bounded by the solidus and liquidus constrain the melting temperature up to 142 GPa and 5880 K between low-pressure diamond-anvil-cell data and high-pressure Hugoniot data. This provides a framework for measuring the temperature along phase boundaries for materials under laser-driven dynamic compression.

$\theta$-TaN is a promising ultrahigh thermal conductivity material, yet a notable discrepancy remains between previous molecular dynamics (MD) simulations and experiments. A systematic atomistic understanding of how directional thermal transport is modulated by synthesis-induced point defects and tensile strain is also lacking. Here, we develop a neuroevolution potential trained on and evaluated against density-functional-theory data to investigate the lattice thermal conductivity $\left({\kappa }_L\right)$ of $\theta$-TaN. By applying a noise extrapolation method to mitigate artificial phonon scattering from errors in force fitting, the pristine ${\kappa }_L$ extrapolated to zero force noise reduces the discrepancy with experiments and Boltzmann transport equation (BTE) predictions, supporting finite force errors as one contributor to the underestimation in previous MD results. On this basis, the effects of four representative point defects, $V_{\text{N}}$, $V_{\text{Ta}}$, ${\text{N}}_{\text{Ta}}$, and ${\text{N}}_i$, are evaluated across concentrations from $2.31\times {10}^{18}$ to $44.4\times {10}^{18}{\mathrm{cm}}^{-3}$. Among the considered defects, ${\mathrm{N}}_{\mathrm{Ta}}$ gives the lowest sampled mean ${\kappa }_L$ at the evaluated concentration limits, accompanied by pronounced perturbations of modes at low frequencies and a high-frequency vibrational feature induced by the defect. Additionally, equiaxial tensile strain ($\varepsilon =0$ to 0.06) monotonically suppresses ${\kappa }_L$ by over one order of magnitude. The consistent trends in the spectral thermal conductivities obtained from MD and the phonon properties derived from three-phonon calculations indicate that bond weakening, phonon softening, reduced phonon group velocities, and shorter relaxation times contribute to the strain-induced reduction in ${\kappa }_L$. This work illustrates the utility of the noise extrapolation method in mitigating artifacts caused by force noise in MD simulations and provides insight into the defect- and strain-modulated thermal transport in $\theta \text{−}\mathrm{TaN}$.

We develop a microscopic theory for how slow Liouvillian sectors are selected in an open correlated lattice. The starting point is not a postulated non-Hermitian band, but a local interacting resonance between an on-site doublon and a branch-resolved nearest-neighbor bond. This resonance selects a complete doublon-bond shell whose doublon component controls reservoir visibility and whose orientation-resolved conversion amplitudes control shell mobility. Projecting the microscopic hopping onto the selected shell yields a branch-selective dimerized channel. In the dilute regime, a boundary doublon-loss channel yields an exponentially slow edge-memory pole through a Zeno-type return. At the shell-critical point, the edge pole is replaced by a near-zero standing-wave doublet with an algebraic coherent spacing. At finite shell filling, a projected continuation of the same parent shell supports number-conserving phase locking on nonoverlapping dimers. Under an additional population closure, the resulting pinned-boundary defect generator yields reciprocal diffusion and nonreciprocal boundary accumulation. The resulting mechanism identifies the reservoir-engineered fast block as the selector of the observable slow sector, while the microscopic parent shell remains fixed.

${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$ is a prototypical metallic van der Waals ferromagnet with itinerant magnetism and a highly tunable Curie temperature, yet how electronic excitations couple to spin and lattice degrees of freedom across its magnetic transition remains largely unexplored. Here, we use two-color pump-probe reflectivity to investigate the coupled electronic, spin, and lattice dynamics. The time-resolved reflectivity exhibits a triexponential relaxation, in which the intermediate component shows an anomaly near the Curie temperature due to enhanced interlayer spin-lattice interactions, while the slowest component displays pronounced critical slowing down with an exponent of $\simeq 0.3$, revealing nonuniversal relaxation dynamics associated with intralayer spin correlations. Furthermore, we observe an emergent nonequilibrium $A_{1g}$ phonon Fano asymmetry that is suppressed in the ferromagnetic phase but anomalously enhanced in the paramagnetic regime, driven by thermally activated anharmonic decay pathways that bridge the kinematic gap to a hot electronic continuum. The pronounced enhancement of the acoustic strain pulse amplitude near ${\mathrm{T}}_c$ further evidences robust magnetoelastic coupling. Overall, our results reveal how magnetic order governs the interplay among critical spin dynamics, electronic continuum excitations, and lattice response in metallic van der Waals ferromagnets.

Non-Abelian gauge fields are of central importance in high-energy and condensed-matter physics and have been experimentally realized in various systems, including quantum materials, ultracold atoms, and artificial structures. Recent theoretical studies suggest that non-Abelian gauge fields can be implemented using multilayer temporal interfaces based on time-reflection and time-refraction effects. This approach benefits from intrinsic temporal tunability and offers a pathway toward extension to higher-order gauge-field scenarios. However, experimental progress has been limited by the challenges in implementing multilayer temporal structures and in achieving required phase control. Here we theoretically introduce and experimentally demonstrate a new scheme to realize non-Abelian synthetic gauge fields through multilayer temporal interfaces combined with geometric pumping. We show analytically and numerically that different sequences of temporal interface operations produce distinct output states, confirming the non-Abelian behaviors. Using time-varying electrical circuits, we observe non-Abelian interference patterns, consistent with theoretical predictions. Our work demonstrates the temporal-interface approach to implement non-Abelian gauge fields and offers a versatile platform for exploring emergent physical states enabled by temporal interfaces.

In the depths of ice giant planets such as Neptune and Uranus, and in inertial confinement fusion targets, chemical reactions can be significantly affected by the extreme pressure and temperature conditions. One of the most intriguing phenomena is the possible formation of diamond from hydrocarbon fluids. Despite experimental observations of diamond formation, the underlying mechanism remains incompletely understood from a first-principles, density functional theory (DFT) perspective. In this work, we provide evidence for the survival and structural evolution of a preexisting diamond phase using large-scale DFT-based and machine-learned molecular-dynamics simulations. Our reverse strategy model, initialized with a diamond structure surrounded by hydrogen, demonstrates that diamond can persist in contact with hydrogen-rich fluid at extreme pressures and temperatures relevant to ice-giant mantles. The time evolution of these systems reveals partial diamond dissolution followed by recovery of the diamond fraction through C–H bond breaking and C–C bond formation. Our Kubo-Greenwood formalism-based transport calculations reveal that the diamond-hydrogen system has lower electrical and thermal conductivity than the random hydrocarbon mixture at 150 GPa and 3000–4000 K. We expect these results to have important implications in the modeling of the structure and magnetic fields of the ice giant planet interiors and improve future inertial fusion energy target designs.

The microscopic origin of high carrier mobility in transition-metal diphosphides remains under debate, with proposed mechanisms including hydrodynamic electron flow and suppressed momentum relaxation associated with spin-momentum locking. $\mathrm{W}{\mathrm{P}}_2$ provides a useful platform for addressing this issue because it crystallizes in two polymorphs: monoclinic $\alpha \text{−}\mathrm{W}{\mathrm{P}}_2$, a topologically trivial semimetal, and orthorhombic $\beta \text{−}\mathrm{W}{\mathrm{P}}_2$, a type-II Weyl semimetal. Here, we grew high-quality α- and $\beta \text{−}\mathrm{W}{\mathrm{P}}_2$ single crystals with residual-resistivity ratios of 3700 and 4200, respectively. Electrical transport measurements yield carrier mobilities of $1.90\times {10}^5$ and $1.88\times {10}^5\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ at 5 K for α- and $\beta \text{−}\mathrm{W}{\mathrm{P}}_2$, corresponding to transport lifetimes ${\tau }_t$ of $6.93\times {10}^{-11}$ and $1.38\times {10}^{-10}$ s. Low-temperature resistivity analysis shows that the data are better described by residual impurity scattering together with a phonon-drag-related contribution than by simple $T^2$ electron-electron or $T^5$ electron-phonon forms. Raman spectra show linewidth broadening and weak Fano-type asymmetry in selected phonon modes, indicating mode-dependent electron-phonon coupling. Analysis of the electronic Raman response gives quantum quasiparticle lifetimes ${\tau }_q$ of $4.25\times {10}^{-14}$ and $3.74\times {10}^{-14}$ s at 5 K for α- and $\beta \text{−}\mathrm{W}{\mathrm{P}}_2$, yielding ${\tau }_t/{\tau }_q=1632$ and 3698, respectively. To account for this large ${\tau }_t/{\tau }_q$, we propose that two mechanisms may play crucial roles: spin-orbit coupling (SOC), which suppresses backscattering for $k$ points near band extrema, and orbital-momentum locking (OML), which restrains large-angle scattering for $k$ points away from band extrema. These results provide a comparative view of carrier scattering in the two phases of $\mathrm{W}{\mathrm{P}}_2$ and suggest that SOC and OML are relevant to the high mobility in transition-metal diphosphides.

We present a theory of ballistic N/F/S and S/F/S junctions with a uniformly precessing magnetization, which generates long-range equal-spin superconducting correlations [Takahashi et al., Phys. Rev. Lett. 99, 057003 (2007), Houzet, Phys. Rev. Lett. 101, 057009 (2008)]. The nonequilibrium distribution of Andreev bound states leads to a strongly nonsinusoidal current-phase relationship for large precession angles. We derive detailed results for ballistic junctions involving partially and fully polarized ferromagnets. In the fully polarized half-metal limit, the magnetization precession switches the junction from an “off” state with vanishing subgap current to an “on” state with finite Andreev conductance and finite Josephson current.

The interplay between crystal structure and electronic band structure has recently encouraged the study of magnetic materials that exhibit the intriguing anomalous Hall effect (AHE). In this context, the magnetic shape memory (MSM) alloy undergoing a structural phase transition is an ideal platform for investigating its effect on transport phenomena. Here, we report various aspects of the scattering mechanism in the ${\mathrm{Mn}}_2\mathrm{NiGa}$ MSM Heusler alloy. In the low-symmetry martensite phase, the scaling behavior of anomalous Hall resistivity reflects that both extrinsic skew scattering and the intrinsic mechanism have nearly equal contributions to the AHE. The obtained value of experimental intrinsic anomalous Hall conductivity (IAHC) is $\sim 12$ S/cm, an order of magnitude lower than the calculated theoretical IAHC, possibly due to twin domain formation or modulated structures in the martensite phase. In contrast, in the high-symmetry austenite phase, the scaling behavior reveals the dominating extrinsic contribution compared to the intrinsic one. Notably, both the quadratic temperature dependence of resistivity and the linear negative magnetoresistance confirm the dominance of electron-magnon coupling in the ${\mathrm{Mn}}_2\mathrm{NiGa}$ alloy. This coupling plays a crucial role by driving the side-jump scattering mechanism, which significantly influences the AHE in the austenite phase. The experimental results suggest that the intrinsic mechanism is suppressed during the transition from the low-symmetry martensite phase to the high-symmetry austenite phase. This is further qualitatively supported by theoretical IAHC calculations, which indicate a lower IAHC value in the austenite phase compared to the martensite phase. These findings indicate that the intrinsic contribution to the AHE weakens as the alloy transforms to the high-symmetry austenite phase, where the strong electron-magnon coupling emerges as a key factor in shaping the transport behavior of the ${\mathrm{Mn}}_2\mathrm{NiGa}$ MSM alloy.

The geometry of the Fermi sea hosts a unique form of quantum topology, playing an equally significant role as the geometry of wave function. It governs the conductance quantization of a metal and is characterized by the Euler characteristic ${\chi }_F$, offering a new perspective in the study of topological quantum matter. Here, we reveal a class of fine-grained topology in the Fermi sea, whose characterization goes beyond ${\chi }_F$. Such topological structure in the symmetry-protected Morse-function regime leads to a nontrivial result that two Fermi seas with identical ${\chi }_F$ but different fine-grained topologies cannot be connected without a Lifshitz transition. To encode this structure, we introduce a structural resolution factor, which exactly captures the deeper topological information of the Fermi sea. When further considering the attractive Hubbard interaction of electrons on Fermi surfaces, we demonstrate that the resulting chiral topological superconducting phases can inherit the fine-grained Fermi sea topology of their parent metallic bands, with differences in these fine-grained structures giving rise to anomalous Majorana boundary states at the interface between two metal/superconductor heterojunctions. This work opens an avenue for exploring the topological richness of the Fermi sea.

The momentum-space derivatives of Bloch wave functions are essential for studying quantum geometry and the equilibrium and response properties of solids. In practical first-principles calculations, these derivatives are obtained via Wannier interpolation of position and related composite matrices. These matrices are initially evaluated on a coarse $\mathit{k}$-point grid using finite-difference approximations and then interpolated to a dense grid. The accuracy of the finite-difference approximation directly impacts the convergence and reliability of the result. In this work, we present two key improvements to the finite-difference calculation of position and composite operators for Wannier interpolation. First, we formulate a translationally equivariant scheme that preserves the underlying symmetries of the system and significantly reduces finite-difference errors. Second, we introduce a higher-order finite-difference approach that yields a more accurate approximation of the $\mathit{k}$-space derivatives by systematically increasing the convergence rate. From a real-space perspective, these improvements correspond to better approximations of the position operator at the locations of the Wannier functions. We also present a generalization of the finite-difference scheme, which may reduce the number of finite-difference points while maintaining accuracy. We demonstrate the effectiveness of our methods by applying them to the calculation of Wannier centers and spreads, electric polarization, off-diagonal position matrix elements, orbital magnetization, and spin Hall conductivity. Our results demonstrate significant reductions in finite-difference errors, the elimination of symmetry-violating errors, and improved convergence with respect to $\mathit{k}$-point sampling. These methods have been implemented in the open-source packages Wannier90 and WannierBerri, and they can be readily adopted in other Wannier-based codes with minimal computational overhead. Our work provides a robust and accurate approach for calculating $\mathit{k}$-space derivatives using Wannier interpolation.

Motivated by the bilayer cuprate superconductors and nickelate superconductor ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$, we investigate the evolution from intralayer to interlayer superconductivity (SC) in finite-width bilayer $t\text{−}J\text{−}{J}_{\perp }$ ladders, where $t$ is the in-plane electron hopping, $J$ is the in-plane spin interaction, and $J_{\perp }$ is the interplane spin interaction. By means of density matrix renormalization group calculations, we map out the quantum phase diagram of the bilayer two-leg ladders by tuning $J_{\perp }$ in a large doping range $\delta =(1/8)–(1/2)$. We find that a large $J_{\perp }$ can always drive interlayer SC by coupling the two layers in both the Luther-Emery liquid (LEL) and Luttinger liquid states. By coupling two LEL states, the in-plane SC evolves to interplane SC either through an intermediate charge-density-wave (CDW) phase or directly, depending on doping ratio. This emergent CDW phase, which exists over a finite doping range, appears to develop from the CDW state of the two-leg ladder at $\delta =1/4$. By coupling two Luttinger liquids, the in-plane Luttinger liquids show a transition to the interplane superconducting phase at large $J_{\perp }$, as reported in previous literature. Interestingly, in the intermediate $J_{\perp }$ regime, we find that, while the in-plane Luttinger liquid features remain stable, the interplane SC can develop an enhanced quasi-long-range order with the power exponent $K_{\mathrm{SC}}^{zz}\sim 1$. Finally, we show that the interlayer SC is also stable by coupling the bilayer three-leg $t\text{−}J$ ladders by a strong $J_{\perp }$ interaction, from both the LEL and Luttinger liquid states.

Bound states in the continuum (BICs), as a rule, are studied in spatially regular or symmetric structures that provide a clear interpretation of the interference underlying the BIC formation mechanism and its practical realization. On the other hand, irregular asymmetric structures with poorly interpreted “accidental” BICs are typically out of the scope of previous studies due to the excessive abundance of parameters. In the present paper, we theoretically address spatially irregular structures and generalize the recently proposed concept of Fourier BICs [Phys. Rev. Lett. 136, 156904 (2026)] to that extent. We consider the waveguide-based Fabry-Pérot (FP) resonator with $N$ mirrors (resonators) located irregularly and derive an explicit BIC formation condition in the limit of weak scattering of the propagating wave by the mirrors. It requires the vanishing of an $N$-term exponential sum, representing a “Fourier transform” of the bound states in the evanescent mode calculated at irregular points of the resonators' positions. It turns out that in the case of weakly scattering identical mirrors, only regular or symmetric structures possess Fourier BICs for $N<5$. Whereas, for $N\ge 5$, Fourier BICs in a waveguide with all distances between adjacent resonators being different become possible. When the mirrors are not infinitesimal, these BICs continuously transform and demonstrate much more complex behavior including the possibility of BICs with irregular intermirror distances for smaller $N$. Analytical considerations are supported by examples of numerical calculations of two-dimensional quantum-mechanical and optical waveguides. The revealed BIC formation condition offers a regular way for designing irregular systems possessing BICs, suggesting, for instance, a universal approach to the design of waveguide systems providing BIC-assisted decoherence suppression.

Strongly correlated $4f$- and $5f$-electron systems often exhibit large effective masses due to cooperation between orbital hybridization and electron localization. In this context, the quadruple perovskite ruthenates $A{\mathrm{Cu}}_3{\mathrm{Ru}}_4{\mathrm{O}}_{12}$ have attracted considerable interest as a rare example of heavy-fermion-like behavior arising from $d$ electron. However, the role of $A$-site cation substitution and its influence on the electronic structure remain unexplored. Here, we report a comprehensive study on the electronic properties of a newly synthesized ${\mathrm{CeCu}}_3{\mathrm{Ru}}_{3.25}{\mathrm{O}}_{12}$ sample, performing using synchrotron-based x-ray absorption spectroscopy (XAS) and photoemission spectroscopy (PES). By optimizing the Ru content under high-pressure synthesis conditions, we obtained a metallic compound exhibiting the highest electronic specific heat coefficient ($\gamma =156\mathrm{mJ}/\mathrm{mol}{\mathrm{K}}^2$) within the $A{\mathrm{Cu}}_3{\mathrm{Ru}}_4{\mathrm{O}}_{12}$ family, together with a reduced effective magnetic moment (${\mu }_{\mathrm{eff}}=2.10{\mu }_{\mathrm{B}}/\mathrm{f}.\mathrm{u}.$), indicating strong electronic correlations and substantial screening of local magnetic moments. The Ce $L_{\mathrm{III}}$-edge XAS measurements revealed an intermediate valence state (${\mathrm{Ce}}^{3.31+}$), indicative of $4f^0–4f^1$ hybridization. A chemical shift observed in the Cu $K$-edge absorption suggests a modified Cu valence state, likely arising from indirect $f–d$ interactions mediated by oxygen ligands. The PES measurements uncover a peak at $\left|\omega \right|\sim$ 19 meV near the Fermi level whose energy and intensity show pronounced temperature dependence below 100 K, resembling the evolution of Kondo resonance peaks seen in $f$-electron systems. These findings suggest the coexistence of $f–d$ and $d–d$ hybridization at different crystallographic sites is likely an important factor for the enhanced $\gamma$, reduced ${\mu }_{\mathrm{eff}}$, and Fermi-liquid behavior in ${\mathrm{CeCu}}_3{\mathrm{Ru}}_{3.25}{\mathrm{O}}_{12}$, offering a platform to explore correlated-electron phenomena in mixed-valent oxide systems.