Pressure provides a clean and continuous route for tuning electronic structure and magnetic interactions in itinerant ferromagnets without introducing chemical disorder. Here, we report high-pressure structural, transport, and electronic structure studies of hexagonal ferromagnetic ${\mathrm{SmCrGe}}_3$, a rare-earth chromium germanide that exhibits giant uniaxial magnetocrystalline anisotropy and strong coupling between localized Sm $4f$ and itinerant Cr $3d$ electrons. Synchrotron high-pressure x-ray diffraction measurements reveal that the hexagonal $P{6}_3/mmc$ structure remains stable up to 10 GPa without a crystallographic phase transition, indicating that the pressure-driven evolution is primarily electronic rather than structural in origin. High-pressure electrical resistance measurements show a nonmonotonic pressure dependence of the Curie temperature ($T_{\mathrm{C}}$) inferred from the resistance anomaly, where $T_{\mathrm{C}}$ initially decreases with pressure, followed by a slight recovery before the magnetic order is suppressed above 6.4 GPa. Concomitantly, a low-temperature resistance minimum emerges above 4.3 GPa, consistent with enhanced Kondo-like scattering associated with Sm $4f$ electrons. Density functional theory calculations on ${\mathrm{SmCrGe}}_3$ reveal a highly pressure-sensitive Cr-derived flat band near the Fermi level. Systematic lattice-parameter tuning calculations further show that anisotropic lattice compression, particularly along the crystallographic $c$, strongly modifies the flat-band position relative to the Fermi level. These results identify ${\mathrm{SmCrGe}}_3$ as a promising platform for studying the coupled evolution of fragile itinerant ferromagnetism, pressure-sensitive flat-band electronic structure, and emergent $4f$-derived correlated scattering under pressure.

Altermagnets ($\text{AMs}$) are spin-compensated materials in which opposite-spin sublattices are connected by a symmetry that causes a spin splitting in their elementary excitations. As there is a strong effect of altermagnetism on domain wall properties, it is quite natural to also expect an enrichment of the physics of magnetic excitations at $\text{AM}$ domain walls. Here, we consider the propagation of spin eigenexcitations along domain walls in easy-axial $d$-wave $\text{AMs}$. Investigating the presence of bound states localized on a domain wall, we find that the effect of the $\text{AM}$ on the bound states strongly depends on the orientation of the domain wall relative to the crystallographic directions. If the domain wall is oriented along a nodal direction [100] or [010], $\text{AM}$ does not change the number of bound states; however, it leads to a nonlinear dispersion and a tilt of the wavefront. The effect of $\text{AM}$ is strongest when the domain wall is oriented along the directions [110] or $\left[\overline{1}10\right]$, i.e., along the directions of the strongest $\text{AM}$ splitting in the magnon spectrum. In this case, (i) the additional gapped bound states appear, (ii) degeneracy of the eigenstates with respect to their polarization (right-hand or left-hand precession of the Néel vector) is removed, and (iii) the localization area of the bound states strongly depends on the eigenfrequency. The latter may lead to strong localization of the bound state at the domain wall. We further consider the influence of a static magnetic field that is applied along the easy axis and find that the magnetic field induces an asymmetry between the localization regions on opposite sides of the domain wall and sets an upper limit on the absolute value of the propagating eigenstate's wave vector.

The notion of quantum symmetry has recently been extended to include reduced-dimensional transformations and algebraic structures beyond groups. Such generalized symmetries lead to exotic phases of matter and excitations that defy Landau's original paradigm. Here, we develop an algebraic framework for systematically deriving the fusion rules of topological defects in higher-dimensional lattice systems with noninvertible generalized symmetries, and focus on a $(2+1)$-dimensional quantum Ising plaquette model as a concrete illustration. We show that bond-algebraic automorphisms, when combined with the so-called half-gauging procedure, reveal the structure of the noninvertible duality symmetry operators, which can be explicitly represented as a sequential quantum circuit. The resulting duality defects are constrained by the model's rigid higher symmetries (lower-dimensional subsystem symmetries), leading to restricted mobility. We establish the fusion algebra of these defects. Finally, in constructing the noninvertible duality transformation, we explicitly verify that it acts as partial isometry on the physical Hilbert space, thereby satisfying a recent generalization of Wigner's theorem applicable to noninvertible symmetries.

Few-layer ${\mathrm{CrI}}_3$ exhibits thickness-dependent interlayer antiferromagnetic coupling and magnetic-field-induced spin-flip transitions. Although bilayer ${\mathrm{CrI}}_3$ has been extensively studied, the spin dynamics of thicker multilayer structures remain less well understood. In this work, we present systematic simulations and analytical modeling of magnetization reversal and antiferromagnetic resonance modes in bilayer (2L), trilayer (3L), and tetralayer (4L) monoclinic ${\mathrm{CrI}}_3$. By solving coupled Landau-Lifshitz equations using parameters benchmarked against bilayer experimental results, we identify thickness-dependent resonance maps, mode frequencies, and critical fields under both out-of-plane and in-plane magnetic fields. The analytical mode frequencies obtained from linearized equations show good agreement with numerical results. We further demonstrate that antiferromagnetic resonances can be tuned by tens of gigahertz through rotation of the magnetic-field angle. These findings reveal thickness-controlled spin dynamics in van der Waals antiferromagnets and highlight their potential for multistate memory and high-frequency spintronic applications.

As a high-thermal-conductivity material, graphite is not only important in thermal management applications, but also serves as a fundamental platform for exploring phonon hydrodynamics at elevated temperatures. However, the modeling and understanding of the spatiotemporal dynamics of heat pulse propagation in finite-size graphite are not yet established. In this work, we target this challenge by directly solving the transient phonon Boltzmann transport equation in real and reciprocal spaces as well as in temporal domain with first-principles input. We investigate the dynamics of both ballistic heat waves and second sound, and uncover the impact of temperature and isotope concentration. In the ballistic regime, the present computational framework accurately captures the ballistic peaks of various phonon branches propagating at distinct speeds and reveals different “peak attenuation” effects induced by elevated temperatures and isotope scattering. In the hydrodynamic regime, we unveil the kinetic formation process of the second sound-wave packet and demonstrate an optimal temperature window around 100–120 K and the monotonic dissipative effect of isotope scattering. Therefore, this study provides not only a robust computational framework, but also deeper physical insights for transient dynamics of heat pulse propagation in graphitic materials.

Spin relaxation results in spin decoherence and a finite spin lifetime, which are detrimental to spintronic devices. To achieve a long spin lifetime desirable for spintronic devices, elucidating the spin relaxation mechanism and factors influencing the spin lifetime is of vital importance. Here, we investigate the spin relaxation in $X$-wave magnets ($X=p,d,f,g,i$) with Rashba spin-orbit coupling within the framework of the D'yakonov-Perel' mechanism. We calculate the tensor of the spin relaxation rate for an arbitrary Néel vector direction in the regime of a weak spin-orbit field. It is found that the spin relaxation rate matrices are anisotropic and can be dictated by magnetic point group symmetry. As an illustration, we study the spin relaxation for a Néel vector along the [001] direction. For the $p$-wave magnet, we derive analytical expressions for the temporal evolution of spins. Moreover, we show that the spin relaxation is highly controllable by the Néel vector and the spin relaxation rate is proportional to the momentum relaxation time, Rashba, and spin-split strengths. Our results shine more light on the fundamental understanding of the spin relaxation mechanism in unconventional $X$-wave magnets.

Multiferroic materials are of great importance for the development of next-generation multifunctional devices. Here, we predict a stable one-dimensional (1D) antiferromagnetic (AFM) semiconductor ${\mathrm{NbI}}_3$ chain, in which moderate electron doping induces site-centered charge order, ferrimagnetism (FIM), and ferroelectric polarization. The asymmetric Jahn-Teller distortion makes adjacent Nb sites inequivalent, and the resulting charge order, combined with bond dimerization, generates ferroelectricity. At 0.5 $e/\text{u.c.}$ doping (where u.c. denotes unit cell), the FIM chain is half metallic and has a calculated polarization-reversal barrier of about 13 meV/u.c. The optimized ferromagnetic configuration suppresses this asymmetric distortion and charge order, linking polarization to the magnetic configuration. Finally, considering the experimental feasibility of doping, we identify Li-intercalated bulk ${\mathrm{NbI}}_3$, i.e., ${\left({\mathrm{NbI}}_3\right)}_2\mathrm{Li}$, as a viable platform to realize the electron-doping effect in the ${\mathrm{NbI}}_3$ chain and the coexistence of magnetic and ferroelectric orders in this system further confirms its multiferroic nature. Our research paves a new way for the design of 1D multiferroic materials.

Anisotropic magnetoresistance (AMR) arises from symmetry lowering of the conductivity tensor induced by magnetic order. In simple ferromagnets, AMR is a relativistic effect, relying on spin-orbit interaction (SOC). Here, we demonstrate that a comparable symmetry lowering can also occur in a nonrelativistic limit. Using tight-binding models, density functional theory calculations, and Boltzmann transport theory, we investigate systems with multiple magnetic sublattices, including both collinear and noncollinear antiferromagnets, as well as ferrimagnetic configurations. We show that AMR and related anisotropies can emerge purely from magnetic order, without the need for SOC, and may reach significant magnitudes. The findings are supported by case studies on toy-model lattices and real materials such as MnN and ${\mathrm{Mn}}_3\mathrm{Sn}$ and are further interpreted using a symmetry analysis based on Neumann's principle. Material candidates that exhibit nonrelativistic anisotropic magnetoresistance are identified by symmetry analysis applied to entries in the MAGNDATA database.

In this paper, we investigate how a topologically ordered state changes to another one from a microscopic point of view. To this end, we focus on the behavior of topological entanglement and 1-form symmetry under decoherence, which induces a phase transition between these states. After a detailed numerical study of the color code as a first case study, we explain how the decoherence changes the topological properties of the state, observing topological entanglement negativity (TEN) and the disorder parameter of the 1-form symmetry. Our results suggest that the above quantities are closely connected with the first and 0th simplicial homology, respectively, and that the transition can be understood from the point of view of decoherence percolation. For a detailed microscopic investigation, we introduce the concept of quasilocal TEN (QLTEN) and show snapshots of the local topological property of the state, which is capable of clearly describing the decoherence percolation. To further investigate how QLTEN and the 1-form symmetry are related to the transition, we introduce the concept of explosive percolation (EP) to the present system, which has received a lot of attention in the last two decades. EP in the present context means that there exists some bias in the decoherence, reducing a large cluster of decohered regions. As a second case study, we consider a toric code on a triangular lattice under an external-field-type decoherence. Detailed numerical study reveals that QLTEN can faithfully describe the emergent Higgs region and the surviving logical qubits. We find that although topological entanglement negativity (TEN), clusters of QLTEN, and string operators strongly correlate with each other in both the color code and the toric code, the two systems react to patterns of EP quite differently. This fact indicates that obtaining a universal understanding of the topological phase transition is challenging even for strongly related systems.

Experimental validation of equation-of-state (EOS) models for high-energy-density applications typically involves measuring the shock Hugoniot, which helps constrain the high-pressure, high-density EOS. However, EOS measurements at below ambient density in the expanded regime are less common. Recent experimental advances allow the isentrope to be inferred from measurements of the density profile of an adiabatically expanding proton-heated plasma, offering the potential to assess various theoretical EOS models over a wide range of below-ambient density conditions. On the theoretical side, determining the expanded-regime EOS poses a considerable challenge for ab initio methods like density functional theory–based molecular dynamics (MD) due to the big simulation cells and large number of orbitals required to simulate these low-density, high-temperature conditions. We thus take a more computationally friendly approach by leveraging the power of MD driven by machine-learned interatomic potentials (ML-IAPs) trained on ab initio simulations. We directly simulate the adiabatic expansion of heated diamond at conditions relevant to experiments using large cells with up to 1.3 million atoms. These simulations, using several different variants of carbon ML-IAPs, are used to extract release isentropes and to study possible microscopic chemistry and phase transitions at play. These insights gained from our MD simulations can serve to guide the design and interpret observations of experiments.

Fabry-Pérot (FP) oscillation arises from interference between coherent paths induced by multiple reflections. In mesoscopic electronic systems, FP oscillation is commonly observed in various one-dimensional (1D) devices. However, in higher-dimensional systems, the presence of numerous transverse channels typically leads to dephasing, which suppresses the overall oscillation. To date, FP oscillation in two-dimensional electronic systems has been reported only in graphene-based devices and, more recently, in the $\mathit{pn}$ junctions of an inverted InAs/GaSb double quantum well. In the latter, electron-hole hybridized band structure plays a crucial role, generating many parallel 1D channels that satisfy nearly identical conditions for constructive interference. In this paper, we propose that this mechanism can be generalized to three-dimensional (3D) systems, such as the nodal line semimetals. We find that due to the spin texture in nodal line semimetals, the electron-to-hole scattering process, and consequently the FP oscillation, are significantly suppressed. However, by introducing ferromagnetic leads, the electron-to-hole scattering can be enhanced, thereby preserving the FP interference. Our results provide a promising way for the implementation of FP oscillation in 3D electric systems.

Topological insulator nanowires provide a versatile platform for studying the interplay between disorder, quantum interference, and symmetry-protected transport. We investigate quantum transport in disordered topological insulator nanowires threaded by an axial magnetic flux. From the length dependence of the conductance, we extract the localization length and characterize the flux-driven delocalization transition near half-integer flux quanta. We determine a localization-length exponent $\nu \simeq 2$, robust against variations of chemical potential and disorder strength, and relate this scaling to the asymptotic dominance of the protected helical channel. This value differs from the localization-length exponent of the integer quantum Hall transition, indicating that the transition is not described by integer quantum Hall critical scaling. Near integer flux quanta, we uncover an unexpected crossover from weak localization at low chemical potential to weak antilocalization at higher chemical potential, followed by a splitting and eventual suppression of the interference peak as the system enters the strongly localized regime.

We investigate nonstabilizerness, also known as “magic”, to understand criticality and exceptional points in non-Hermitian quantum many-body systems. Our focus is on parity-time ($\mathcal{PT}$)-symmetric spin chains, specifically the non-Hermitian transverse-field Ising and XX models. We calculate stabilizer Rényi entropies in their ground states using non-Hermitian matrix product state methods. Our findings show that magic exhibits unique and model-specific signs of phase transitions. In the Ising chain, it peaks near the regular Hermitian-like critical line but disappears across exceptional points. In contrast, in the XX chain, it reaches its maximum at the exceptional line where $\mathcal{PT}$ symmetry is broken. Finite-size scaling reveals that these effects become more pronounced with larger systems, highlighting nonstabilizerness as a sensitive marker for both quantum criticality and non-Hermitian spectral degeneracies. We also investigate magic in momentum space for the XX model analytically and find that it reaches a minimum around exceptional points. Our results indicate that magic takes extremal values at the exceptional points and serves as a valuable tool for examining complexity, criticality, and symmetry breaking in non-Hermitian quantum matter.

We investigate the metal-insulator transition driven by the onsite repulsive interaction $U$ in an altermagnetic Hubbard model defined on a Lieb lattice. Using the slave-rotor approach at half-filling, we find that the system exhibits a cascade of interaction-driven phase transitions. As $U$ increases, the system evolves from a normal metal to an altermagnetic metal, then to an altermagnetic insulator, and eventually to an altermagnetic Mott insulator characterized by the complete suppression of the quasiparticle weight. These phases are supported by the calculation of the electronic spectral function, which features spin-split bands in both the metallic and insulating regimes. However, the spin splitting becomes substantially suppressed in the Mott-insulating phase. Our results suggest that the observation of spin splitting in the spectral function of $d$-wave altermagnets with a Lieb-lattice-like structure may be limited to the weak-to-moderate correlation regime.

The electrical conductivity of high-pressure silicates profoundly influences the interior dynamics of rocky planets. Employing the Kubo-Greenwood formalism, we perform ab initio calculations of electronic conductivity in Fe-bearing post-perovskite under super-Earth mantle conditions, up to 4000 K and 500 GPa. Electronic structures are obtained via many-body perturbation theory, incorporating dynamical screening and correlations among localized Fe-$3d$ orbitals. In contrast to (Fe,Mg)O, for which metallization has been reported at comparable conditions, our results indicate that post-perovskite with Earth-like Fe contents is unlikely to metallize in super-Earth mantles via band-gap closure, yielding negligible low-frequency conductivity. Thus band conduction is negligible under the conditions examined. Small-polaron hopping is a plausible explanation for the larger measured total conductivity, but testing this hypothesis requires explicit calculations beyond the present band-conduction treatment.

Donor impurities in wide direct band gap semiconductors provide a promising platform for spin-photon quantum technologies by combining a donor spin qubit with optically addressable transitions. In ZnO, the shallow donor with the largest reported binding energy has long been associated with the $I_{10}$ bound exciton line, but its microscopic origin has remained unresolved. Here we demonstrate the controlled formation and identification of this donor as a Sn-Li complex through a combination of ion implantation, annealing, optical spectroscopy, and first-principles calculations. Resonant two-laser coherent population trapping measurements reveal an electron–${}^{119}\mathrm{Sn}$ hyperfine interaction of $392\pm 15\mathrm{MHz}$, establishing a coupled electron-spin-1/2, nuclear-spin-1/2 system with one of the largest hyperfine couplings reported for shallow donors in semiconductors. Density functional theory calculations show that a nearest-neighbor ${\mathrm{Sn}}_{\mathrm{Zn}}-{\mathrm{Li}}_{\mathrm{Zn}}$ complex has favorable formation energetics, donor character with the electron localized on Sn, and an extrapolated hyperfine interaction consistent with experiment. The large donor binding energy and excited-state structure indicate enhanced thermal robustness of the optical transition relative to conventional group-III donors, while the strong hyperfine interaction enables fast electron-nuclear spin control and prospects for direct nuclear-spin-photon interfaces. We further observe efficient optically induced nuclear spin polarization, highlighting a path toward nuclear spin initialization. More broadly, our results reveal how a donor-acceptor complex can access previously unexplored regimes of shallow donor physics, extending the design space of donor quantum defects beyond isolated substitutional dopants.

The order from quantum disorder (OFQD) effect was first discovered in frustrated quantum spin systems. Recently, OFQD was also found in Rashba spin-orbit-coupled (SOC) systems even on a square lattice. Here we study the role of OFQD in the experimentally realized weakly interacting bosonic quantum anomalous Hall system of spinor bosons in an optical lattice. We perform microscopic nonperturbative OFQD calculations and construct an effective action based on symmetry considerations. These two complementary approaches establish an OFQD-induced quantum critical regime at finite Zeeman field. In particular, we show that the competition between the OFQD-generated effective potential and the Zeeman field drives a continuous quantum phase transition from the canted-antiferromagnetic superfluid phase to the $Z$-ferromagnetic superfluid phase with dynamical exponent $z=2$. We further determine the associated finite-temperature quantum critical scaling and discuss experimentally relevant signatures in existing cold-atom platforms. Our results establish OFQD as a mechanism for an interaction-driven quantum phase transition in the bosonic quantum anomalous Hall system.

$\beta \text{−}{\mathrm{FeSi}}_2$ exhibits exceptional oxidation resistance, commonly attributed to the formation of a dense, protective ${\text{SiO}}_2$ surface layer; however, the atomistic pathway governing the emergence of this layer and the subsequent suppression of oxidation remains elusive. In this work, we develop an active-learning MACE interatomic potential for the reactive Fe-Si-O system and incorporate a Fermi-like potential wall to enable one-sided reactive molecular-dynamics simulations of $\beta \text{−}{\mathrm{FeSi}}_2$ surface oxidation. By analyzing 100 statistically independent trajectories, we find that self-limiting oxidation on both Si-terminated and Fe-terminated surfaces is consistently associated with the development of an extended connected Si-O network within the oxidized interfacial region. The Si-terminated surface passivates through direct oxidation of exposed Si atoms, whereas the Fe-terminated surface first undergoes Fe oxidation before oxygen reaches the subsurface Si-rich region and forms an extended connected Si-O network. Statistical analysis shows that Fe-O-Fe connectivity is either negligible or incomplete and does not constitute the primary passivating framework. Species-resolved density profiles ${\rho }_{\alpha }(z,t)$ reveal that oxidation proceeds through coupled oxygen incorporation, substrate-atom migration, and interfacial reconstruction, rather than simple inward oxygen diffusion into a static substrate. These results support a connectivity-based microscopic picture in which the development of an extended Si-O network is consistently associated with self-limiting oxidation of $\beta \text{−}{\mathrm{FeSi}}_2$ surfaces, and they provide a transferable computational protocol for exploring oxidation mechanisms in transition-metal silicides and related reactive materials.