A first-order structural phase transition is typically a displacive or reconstructive transformation. The latter has been considered a nondirect group–subgroup symmetry transition. However, with an alternative pathway, recent group-theoretical symmetry analysis predicts that such a reconstructive transition can be realized via a multistep displacive mode. So far, no direct observations of such a displacive transition pathway under pressure have been reported because of the lack of sufficient temporal resolution. Here, we present our experimental results on the phase transition of tin with a specially designed ultrafast time-resolved x-ray diffraction (tens of microseconds) combined with a series of rapid compressions (up to 51.5 TPa/s), revealing the missing region in both the time domain and compression-rate range between static and shock compression. The pressure-induced first-order phase transition from $\beta -\mathrm{Sn}\left(I{4}_1/amd\right)$ to γ-Sn($I4$/mmm) without direct symmetry operation shows distinct displacive characteristics in the sequential x-ray diffraction measurements, and the transition time is observed to depend on the compression rate. The deficit of summed phase fraction of β-Sn and γ-Sn from unity directly derived from diffraction peak intensities during the phase transition shows a clear compression-rate-dependent profile, which indicates the existance of an intermediate phase. Solid-state nudged elastic band calculations confirm the collective displacive paths of all atoms during the transition, and the corresponding XRD simulated patterns show results consistent with the experimental time-resolved XRD observations. This dynamic structural evolution occurs on the microsecond time scale, which is orders of magnitude shorter than conventional high-pressure XRD experiments. Our results shed new light on the dynamics of the traditionally assumed reconstructive phase transition on the microsecond time scale.

Understanding how complex entanglement structures emerge is a central problem in quantum many-body physics. Recent work by Zhang et al. [Phys. Rev. Lett. 137, 020404 (2026)] has considered structured initial states prepared by evolving a product state under a chaotic Hamiltonian for a finite time before quenching to the target Hamiltonian. In this setup, total entanglement entropy growth in many-body localized systems exhibits two distinct regimes, first increasing and then decreasing as the initial entanglement is tuned. In this work, we identify the physical origin of this behavior by analyzing the dynamics of both the Rényi entanglement entropy and the Wehrl-Rényi entropy in the random-field XXZ model, the latter of which characterizes multipartite entanglement. We show that a similar nonmonotonic dependence on the initial entanglement also appears in the net growth of the Wehrl-Rényi entropy for product states polarized along the $z$ direction. The first regime is governed by a finite local magnetization associated with local integrals of motion, while the second reflects intersite correlations. In contrast, for product states in the $x/y$ direction, the entanglement growth exhibits a monotonic decay. Our results provide a more fine-grained picture of how distinct initial-state properties shape entanglement dynamics in many-body localized systems.

Magnetoelectric multiferroics promise direct cross control between coexisting ferroelectric and ferromagnetic orders, which is of interest for applications in magnetism and spintronics. A particularly interesting type of cross control is found in spin-spiral multiferroic ${\mathrm{Mn}}_2{\mathrm{GeO}}_4$, in which a ferroelectric multidomain distribution can be globally inverted by a single magnetic field sweep. In this work we show that this repeatable response is not obtained immediately after entering the multiferroic phase via zero-field coolling. Instead, an initial metastable multidomain state forms in which polarization, magnetization, and antiferromagnetic order do not yet minimize the trilinear magnetoelectric coupling. Using optical second-harmonic generation for ferroelectric domain imaging, we demonstrate that a single field cycle deterministically drives the system from the initial metastable state into an equilibrium domain configuration that shows repeatable domain interconversion. This initialization behavior originates from a deterministic pathway from metastable to equilibrium domain patterns, in contrast to the more common—and less reliable—stochastic domain “training” procedures that require repeated field cycles. Understanding the initial domain evolution thus enables reliable cross control in magnetoelectric devices with highly interlinked order parameters.

The interplay between spin reorientation and topological electronic structure in two-dimensional (2D) van der Waals (vdW) ferromagnets (FMs) is a core issue for understanding how magnetic anisotropy couples to nontrivial topological charge transport. Although spin reorientation transitions (SRTs) are ubiquitous in 2D metallic FMs, their role in reshaping electronic-topology–driven thermodynamic and transport properties, especially magnetotransport and thermoelectric responses, has remained largely unexplored. Here, we address this issue in ${\mathrm{Fe}}_4{\mathrm{GeTe}}_2$, a room-temperature quasi-2D vdW FM, through comprehensive temperature-dependent magnetization, specific-heat, magnetotransport, and thermoelectric measurements. Magnetization and specific-heat measurements establish a reorientation of the magnetic easy axis near $T_{\mathrm{SRT}}\sim 100\mathrm{K}$, in addition to ferromagnetic ordering at $T_C\sim 270\mathrm{K}$. Across the SRT, the Seebeck coefficient and the anisotropic magnetoresistance display pronounced anomalies, suggesting a Fermi-surface reconstruction. The magnetoresistance shows a characteristic two-step field dependence: a low-field enhancement near the SRT associated with carrier scattering from canted spins and evolving domains, followed by a higher-field negative response as spin fluctuations are progressively suppressed. The concurrent sign change of the ordinary Hall coefficient $R_0$ and the sharp anomaly in the anomalous Hall resistivity (${\rho }_{yx}^A$) across the SRT further suggest a temperature-driven modification of the underlying band topology. Furthermore, analysis of the anomalous Hall conductivity ${\sigma }_{yx}^A$ and scaling behavior of the ${\rho }_{yx}^A$ reveals that the Berry-curvature-driven anomalous Hall response below $T_{\mathrm{SRT}}$ is substantially modified above the transition. This study indicates spin reorientation as an efficient internal control parameter between distinct magnetotransport regimes in a 2D vdW FM, offering a symmetry-controlled route for engineering spin-polarized electronic states and domain-texture-driven functionalities.

Rutile ${\mathrm{RuO}}_2$ has recently attracted great interest, as its magnetic ground state remains controversial. Experimental studies have reported either nonmagnetic (NM) or altermagnetic (AM) ground states in different crystalline samples of ${\mathrm{RuO}}_2$, highlighting the need for a reasonable explanation to resolve this contradiction. In this study, density functional theory calculations are performed to reveal the correlation-sensitive and strain-dependent magnetism of bulk ${\mathrm{RuO}}_2$. On one hand, multiple AM phases with different magnitudes of the spin magnetic moment are identified for ${\mathrm{RuO}}_2$ by employing Hubbard's $U$ parameter as a perturbation probe. On the other hand, when appropriate strains that significantly change the crystal cell volume are applied, the ground state of ${\mathrm{RuO}}_2$ is suggested to undergo transitions between the NM state (with no spin splitting) and the magnetic states (with spin splitting in the band structure). These findings not only demonstrate intriguing physics in $4d$-electron-correlated ${\mathrm{RuO}}_2$, but also retain its potential for spintronic applications.

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.