The structure of the chromium dihalides $\mathrm{Cr}{X}_2$ ($X$ = Br, I) resembles that of many other transition-metal dihalides and dichalcogenides, but the Jahn-Teller distortion arising from the ${\mathrm{Cr}}^{2+}$ ions makes the $\mathrm{Cr}{X}_2$ structures distinct from most of these other compounds. Nevertheless, the $\mathrm{Cr}{X}_2$ compounds have received little study, with the helimagnetic order of ${\mathrm{CrBr}}_2$ and ${\mathrm{CrI}}_2$ being reported only recently. We used neutron powder diffraction to study the structure of ${\mathrm{CrBr}}_2$ and ${\mathrm{CrI}}_2$ at high temperature and found interpolytypic transitions in both of these compounds. Monoclinic ${\mathrm{CrBr}}_2$ ($C2/m, \beta =94.5^{\circ }$) and orthorhombic ${\mathrm{CrI}}_2$ ($Cmc{2}_1$) transition to the same polytype at high temperature, a distorted version of the ${\mathrm{CdCl}}_2$ structure with a $C2/m$ space group and a monoclinic $\beta$ angle of ${117}^{\circ }$. The phase transition occurs by layer sliding for ${\mathrm{CrBr}}_2$ and an additional change of layer orientation for ${\mathrm{CrI}}_2$. The intralayer structure is largely unchanged, with a possible small enhancement of the Jahn-Teller distortion on warming.

The dynamics of quantum many-body systems in the chaotic regime are of particular interest due to the associated phenomena of information scrambling and entanglement generation within the system. While these systems are typically intractable using traditional numerical methods, an effective framework can be implemented based on dual-unitary circuits which have emerged as a minimal model for maximally chaotic dynamics. In this work, we investigate how individual two-body operators influence the global dynamics of circuits composed of dual unitaries. We study their effect on entanglement generation while examining it from both bipartite and multipartite perspectives. Here we also highlight the significant role of local unitaries in the dynamics when paired with operators from the dual-unitary class, showing that systems with identical entangling power can exhibit a range of differing entanglement growth rates. Furthermore, we present calculations establishing time-step-dependent lower bounds, which depend on both the initial state and the entangling power of the constituent operators. Finally, we find that time-evolving an initial state composed of pair products generates a state with nearly maximal multipartite entanglement content, approaching the bounds established by Absolutely Maximally Entangled (AME) states.

We investigate the quantum dynamics of a one-dimensional quasiperiodic system featuring a single-particle mobility edge (SPME), described by the generalized Aubry-André model. This model offers a unique platform to study the consequences of coexisting localized and extended eigenstates, which contrasts sharply with the abrupt localization transition in the standard Aubry-André model. We analyze the system's response to a quantum quench through two complementary probes, entanglement entropy (EE) and subsystem information capacity (SIC). We find that the SPME induces a smooth crossover in all dynamical signatures. The EE saturation value exhibits a persistent volume-law scaling in the mobility-edge phase, with an entropy that continuously decreases as the number of available extended states decreases. Complementing this, the SIC profile interpolates between the linear ramp characteristic of extended systems and the information trapping behavior of localized ones, directly visualizing the mixed nature of the underlying spectrum. Our results establish unambiguous dynamical fingerprints of a mobility edge, providing a crucial noninteracting benchmark for understanding information and entanglement dynamics in more complex systems with mixed phases.

High pressure typically enhances thermal conductivity by strengthening atomic interactions. However, PdS has recently been reported to exhibit an unusual pressure-induced suppression of thermal conductivity, which in turn leads to a remarkable enhancement in its thermoelectric performance at high pressure. These insights motivate the search for additional materials that exhibit anomalous thermal-transport behavior under high pressure. Here, we find that hydrostatic pressure induces an anomalous change in lattice thermal conductivity (${\kappa }_l$) in antifluorite structure ${\mathrm{Li}}_2\mathrm{Te}$ by density-functional theory and phonon Boltzmann-transport calculations. The lattice thermal conductivity decreases monotonically under pressure, dropping by 72% to $1.99\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ at 40 GPa compared to ambient conditions. This anomalous behavior arises from the broadened acoustic branches and the enlarged acoustic-optical (a-o) phonon gap under high pressure, which together intensify phonon scattering. The enhanced anharmonicity under pressure is evidenced by both flattened frozen-phonon potentials and enhanced Grüneisen parameters. This work establishes ${\mathrm{Li}}_2\mathrm{Te}$ as a prototypical system for pressure-mediated thermal-transport tuning and highlights phonon scattering as a critical design parameter for engineering materials.

We present magnetization and magnetoresistance measurements obtained on Co thin films with collapsed hard-magnetization axes—a presence of sharp peaks in the angular variations of the remnant magnetization and the coercivity, centered 90 degrees off of the easy axis. A clear correlation between these peaks and the singularities observed in the respective angular remnant magnetoresistance variations is identified. We reveal, with the aid of a model developed here, that there is only an anisotropic magnetoresistance contribution to the remnant magnetoresistance of our films. These results strongly support the presumption that systems with collapsed hard axes consist of grains with two slightly misaligned easy axes. While at saturation each of them behaves as a monodomain, at remanence it splits up in two domains, relative to the two local easy axes. Unlike previous conjectures, our results corroborate with the hypothesis that these domains coexist for all in-plane magnetic field orientations and not only for in collapse region. Whereas in the latter the two domains form scissorlike configurations, these form a small angle, which varies in an undulatory manner with the field orientation.

We investigate the thermodynamic properties of the anisotropic magnetocaloric effect, specific heat, and spin-phonon coupling in single-crystalline van der Waals antiferromagnet $\mathrm{FeP}{\mathrm{S}}_3$, focusing on the second-order antiferromagnetic to paramagnetic phase transition near the Neel temperature $T_{\mathrm{N}}\sim 119\mathrm{K}$. A sharp λ-type anomaly in the heat capacity confirms the continuous nature of the transition, thereby ensuring that the magnetic entropy change ($\mathrm{\Delta }{S}_M$) can be reliably derived from magnetization measurements via the Maxwell relation. Owing to the strong uniaxial anisotropy, $\mathrm{\Delta }{S}_M$ is strongly orientation dependent and reaches up to 4.2 $\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ for magnetic fields applied along the $c$ axis at 6 T, while isothermal magnetization measurements reveal significant differences between the $c$-axis and $ab$-plane responses, approaching $\sim 2.32\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ at 5 T. A universal scaling analysis of $\mathrm{\Delta }{S}_M$ further supports the second-order nature of the magnetic phase transition. Strong interactions between the spin and lattice degrees of freedom are suggested by complementary Raman spectroscopic studies that show distinct signs of spin-phonon coupling, including phonon softening in the magnetically ordered phase. These results highlight the magnetocaloric effect as a thermodynamic probe of entropy-driven lattice dynamics in two-dimensional Ising-type antiferromagnets and show that it functions as a thermodynamic probe of spin-lattice coupling in $\mathrm{FeP}{\mathrm{S}}_3$.

Temperature ($T$)- and depth-dependent valence band (VB) electronic structures of an $\mathrm{Al}{\mathrm{O}}_x$-capped $L{2}_1$-ordered $\mathrm{C}{\mathrm{o}}_2\mathrm{MnSi}$ (CMS) thin film were studied by hard x-ray photoelectron spectroscopy (HAXPES) combined with x-ray total reflection (TR) to reveal the electronic states of the inside of CMS film (bulk) and near-interface region of CMS beneath the $\mathrm{Al}{\mathrm{O}}_x$ layer. The depth-dependent magnetic states of Co and Mn in CMS were also studied by magnetic circular dichroism (MCD) in core-level HAXPES measurements combined with TR. The VB HAXPES spectra obtained at $T=20$, 100, 200, and 300 K showed the clear $T$ dependence in the spectral shapes for both the near-interface and bulk regions of CMS, but the $T$ dependence of electronic states between the near-interface and bulk regions were different as well as the $T$-dependent magnetization of CMS for the near-interface and bulk regions obtained by the Co and Mn $2p$ core-level MCD-HAXPES measurements. The $T$-dependent VB HAXPES spectra of CMS in the bulk region qualitatively agreed with the electronic structure calculations with the disordered local moment method for bulk CMS, indicating the importance of the spin fluctuations on the electronic states of bulk CMS at a finite $T$ and the enhanced spin fluctuations in the near-interface region of CMS. These results suggest that the direct probing of the electronic and magnetic states of the insulator/ferromagnet heterojunctions in a nondestructive way is important to reveal the properties of ferromagnet for the near-interface and bulk regions at a finite $T$.

Projected entangled-pair states (PEPS) have proven effective in capturing chiral spin liquid ground states, yet the presence of long-range “gossamer” correlation tails raises concerns about their ability to accurately describe bulk gaps. Here, we address this challenge and demonstrate that PEPS can reliably characterize gapped bulk excitations in chiral topological phases. Using a variational principle for excited states within a local mode approximation, we establish that correlation functions decaying faster than $r^{-2}$ are not necessarily related to gapless modes and thus long-range “gossamer” correlation tails in chiral PEPS do not contradict the presence of a bulk gap. This framework is validated in the spin-$\frac{1}{2}$ Kitaev model with a chiral term, where PEPS yields excitation gaps that agree well with exact solutions. Extending our approach to the ${\mathbb{Z}}_3$ Kitaev model, we present compelling evidence for its chiral ground state and accurately resolve its gapped excitations. These findings thus solidify PEPS as a powerful tool for studying both ground and excited states in chiral topological systems, thereby bridging a key gap in the understanding of their bulk properties.

Electron microscopy techniques such as electron energy-loss spectroscopy (EELS) facilitate the spatiospectral characterization of plasmonic nanostructures. In this work, a time-dependent perspective is presented that significantly enhances the utility of EELS. In particular, this approach facilitates the analysis of the dynamics of plasmonic excitations that repeatedly interact with swift electrons in a STEM-EELS configuration. This includes the bulk plasmon mode, which can only be excited by penetrating electron beams, and the fundamental surface plasmon polariton modes propagating along the wire, which can be excited by both penetrating and aloof trajectories. In addition, the role of higher-order azimuthal surface plasmon polariton modes, often overlooked for very thin wires, is observed and analyzed in both the energy-loss spectrum and from the dynamical perspective. Such a complete understanding of the interaction of electrons and plasmonic excitations is key for the design of efficient plasmonic sensors, the study of hot electron dynamics in metals, and applications in the context of electron quantum optics, where full control of the spatial and temporal characteristics of the fields at the nanometer and femtosecond scales is highly desirable.

We propose a scheme to realize a topological superconductor and Majorana bound states (MBSs) in a one-dimensional metal nanowire on the surface of a helical altermagnet and in proximity to an $s$-wave superconductor, removing the requirement of conventional spin-orbit coupling and net magnetism. Through gauge transformation, we demonstrate that the helical frame naturally induces spin-momentum locking while the altermagnetism breaks time-reversal symmetry. The topological superconducting phase is well tuned by the chemical potential, altermagnet strength, and helical frequency. Furthermore, our transport calculation results reveal quantized conductance signatures: a $2e^2/h$ zero-bias peak at the nanowire ends and a $4e^2/h$ tunneling conductance at the domain wall of nanowires with opposite chirality, detected via a metal lead and scanning tunneling microscopy, respectively. Our research offers different perspectives on finding MBSs.

Topological polarization textures in ferroelectrics offer pathways to dense memory, neuromorphic computing, and controlled probes of topology in solids. In rhombohedral barium titanate, theory has identified stable antiskyrmions of topological charge −2 that fractionalize into six −1/3 hotspots, termed topological quarks. Here, we extend this landscape to Zr-substituted barium titanate (BZT) using a first-principles parameterized effective Hamiltonian framework. In an ordered 12.5% composition, the chemically doubled periodicity enforces an alternation along [111]: one half hosts the −2 antiskyrmion (six −1/3 quarks), the other a +4 skyrmion (six +2/3 quarks). The two share the same six-vortex scaffold (threefold motif) but differ in the core-level polarization texture, resulting in an integer +1 per vortex offset in the plane-integrated (slice) topological charge. In random BZT, nanodomains remain inducible and cryogenically stable, yet quenched disorder pins and distorts the vortices, producing a heterogeneous, skyrmion-glass–like state with fluctuations of the topological charge along the nanodomain axis. Thermal stability maps show that pure barium titanate retains −2 textures up to ∼100 K, whereas in BZT the collapse temperature is nonmonotonic, with a minimum near 6–8% Zr, reflecting competition between ferroelectric softening and disorder pinning. Importantly, the 12.5% ordered arrangement remains rhombohedral above 300 K, enabling field-stabilized nanodomains at 293 K. Under a local [111] bias, the ordered system carries +4 slice charge, while the random composition fragments under the same conditions. These results establish BZT as a platform for chemically programmed, fractionalized ferroelectric topology from cryogenic to room temperature and suggest routes to multistate, reconfigurable devices.

The aim of this work is to study the dynamics of quantum systems subjected to a localized fermionic source in the presence of bulk dephasing. We consider two classes of one-dimensional lattice systems: (i) a noninteracting lattice with nearest neighbor and beyond, i.e., long-ranged (power-law) hopping, and (ii) a lattice that is interacting via short-range interactions modeled by a fermionic quartic Hamiltonian. We study the evolution of the local density profile $n_i\left(t\right)$ within the system and the growth of the total particle number $N\left(t\right)$ in it. For case (i), we provide analytical insights into the dynamics of the nearest-neighbor model using an adiabatic approximation, which relies on assuming faster relaxation of coherences of the single particle density matrix. For case (ii), we perform numerical computations using the time-evolving block decimation (TEBD) algorithm and analyze the density profile and the growth exponent in $N\left(t\right)$. Our detailed study reveals an interesting interplay between Hamiltonian dynamics and various environmentally induced mechanisms in open quantum systems, such as local source and bulk dephasing. It brings out rich dynamics, including universal dynamical scaling and anomalous behavior across various time scales and is of relevance to various quantum simulation platforms.

We investigate off-diagonal matrix elements of local operators in integrable spin chains, focusing on the isotropic spin-$1/2$ Heisenberg chain ($XXX$ chain). We employ state-of-the-art algebraic Bethe ansatz results, which allow us to efficiently compute matrix elements of operators with support up to two sites between generic energy eigenstates. We consider both matrix elements between eigenstates that are in the same thermodynamic macrostate, as well as eigenstates that belong to different macrostates. In the former case, focusing on thermal states we numerically show that matrix elements are compatible with the exponential decay as $exp(-L|M_{ij}^{\mathcal{O}}\left|\right)$. The probability distribution functions of $M_{ij}^{\mathcal{O}}$ depend on the observable and on the macrostate, and are well described by Gumbel distributions. On the other hand, matrix elements between eigenstates in different macrostates decay faster as $exp(-|{M^{\prime }}_{ij}^{\mathcal{O}}\left|L^2\right)$, with ${M^{\prime }}_{ij}^{\mathcal{O}}$, again, compatible with a Gumbel distribution.

Quantum spin systems with low symmetries of the magnetic properties are studied. It is shown that the low symmetry yields special effects of their magnetic characteristics. Magnetic moments induced by the external magnetic field can be nonparallel to the direction of the field. Also, components of the magnetic susceptibility of such systems can be negative in a large range of the field and temperature values, i.e., they manifest diamagnetic behavior. The origin of the effect is totally quantum. Such a behavior is generic for quantum paramagnets, low-dimensional quantum spin systems, and for quantum spin systems with geometrical frustration of spin-spin couplings. The effect can be important for applications of such quantum systems, e.g., in the creation of metamaterials or in quantum computing.

Classical spin liquids are disordered magnetic phases, governed by local constraints that often give rise to flat-band ground states. When constraints take the form of a zero-divergence field within a cluster of spins, the spin liquid is often described by an emergent Coulomb gauge theory. Here, we introduce an interaction $\eta$ between these clusters of spins that compete with the zero-divergence field. Using a framework embracing both the connectivity matrices of graph theory and the topology of band structures, we develop a generic theory of interacting-cluster Hamiltonians. We show how flat bands remain at zero energy up to finite interaction $\eta$, until a dispersive band becomes negative, stabilizing a spiral spin liquid with a hypersurface of ground-state manifold in reciprocal space. This hypersurface can be interpreted as an effective Fermi surface in the spectrum of the parent system, acting as a tunable energy selector despite the absence of particle filling. This effective Fermi surface serves as a mold for the apparition of the half-moon patterns in the equal-time structure factor. Our generic approach enables to extend the notion of half moons to the perturbation of higher-rank Coulomb fields and pinch-line spin liquids. In particular, multifold half moons appear when unconventional gauge charges, such as potential fractons, are stabilized in the ground state. Finally, half-moon phases can be tuned across the equivalent of a Lifshitz transition, when the hypersurface manifold changes topology.

Synthetic antiferromagnets (SAFs) have attracted considerable interest for high-frequency device applications due to their ultrafast dynamical characteristics. While most theoretical models treat SAFs as uniform macrospins, the localized oscillation and precession dynamics of antiferromagnetically coupled domain walls (DWs) remain largely unexplored in regimes beyond the conventional Walker breakdown paradigm. Here, using a one-dimensional collective-coordinate ($q\text{−}\psi$) DW model, we systematically investigate the oscillation and precession of DWs in SAFs. We reveal that these dynamics emerge specifically during the chirality-breaking transition of the upper-layer DW, as it transforms between Néel and Bloch configurations—a mechanism distinct from the classical Walker scenario. We demonstrate that high oscillation frequencies are achieved when the Dzyaloshinskii-Moriya interaction effective fields in the two layers differ significantly, while the dampinglike spin-orbit torque (SOT) fields remain closely matched. Moreover, by introducing a fieldlike SOT effective field along the $z$ direction through geometric engineering, the frequency can be linearly enhanced, offering a clear pathway toward THz operation. These findings provide not only a deeper understanding of chiral symmetry breaking in DW dynamics but also practical strategies for designing high-frequency DW oscillators based on SAFs.

The tetratrillium lattice has recently been proposed as being responsible for the dynamical properties observed in the $S=1$ langbeinite compound ${\mathrm{K}}_2{\mathrm{Ni}}_2{\left({\mathrm{SO}}_4\right)}_3$. Here, we study in detail the classical spin liquid properties of this lattice of tricoordinated tetrahedra using classical Monte Carlo and large-$N$ theory calculations. In the large-$N$ limit, we find that the system presents a gapped spectrum with flat bottom bands, giving rise to a fragile spin liquid with exponentially decaying correlations according to the classification of classical spin liquids. We confirm that this scenario also holds in the more realistic Ising and Heisenberg cases, for which the system does not exhibit any finite-temperature phase transition, and the low-temperature spin structure factors exhibit excellent quantitative agreement with the large-$N$ theory. We also provide insight into the quantum $S=1/2$ limit by performing pseudo-Majorana functional renormalization-group calculations at finite temperatures, and we discuss the possible phases that can arise in the ground state due to quantum fluctuations.

We consider the mass-imbalance effect on the clustering in a one-dimensional two-component Fermi gas with coexistent even- and odd-wave interactions resulting in different configurations of clustering phases. We obtain the solutions of both stable two- and three-body cluster states with different mass ratios and configurations by solving the corresponding variational equations. We numerically map out phase diagrams consisting of the $s$- and $p$-wave pairing phases, and trimer phase with different configurations, in a plane of $s$- and $p$-wave pairing strengths. Within the explored ranges of $s$- and $p$-wave pairing strengths, the in-vacuum three-body states are always more deeply bound than the two-body ones. While for the in-medium case, the Cooper trimer phase dominates over the pairing phases when both $s$- and $p$-wave interactions are moderately strong. There is also a competition between different clustering configurations of three-body clustering.

Given the prevalence of superconducting platforms for uses in quantum computing and quantum sensing, the simulation of quantum superconducting circuits has become increasingly important for identifying system characteristics and modeling their relevant dynamics. Various numerical tools and software packages have been developed with this purpose in mind, typically utilizing the harmonic oscillator basis or the charge basis to represent a Hamiltonian. In this work, we instead consider the use of discrete variable representations (DVRs) to model superconducting circuits. In particular, we use ‘‘sinc DVRs’’ of both charge number and phase to approximate the eigenenergies of several prototypical examples, exploring their use and effectiveness in the numerical analysis of superconducting circuits. We find that not only are these DVRs capable of achieving decoherence-accurate simulation, i.e., accuracy at the resolution of experiments subject to decay, decoherence, and dephasing, they also demonstrate improvements in efficiency with smaller basis sizes and better convergence over standard approaches, showing that DVRs are an advantageous alternative for representing superconducting circuits.