In recent years, layered kagome magnets have emerged as promising platforms for Berry curvature engineering and unconventional transport phenomena. Here, we present the single-crystal growth, magnetization, and electrical transport characterizations of the van der Waals-like layered antiferromagnet ${\mathrm{GdTi}}_3{\mathrm{Bi}}_4$. The system exhibits pronounced field induced first-order phase transitions. Comprehensive frequency, temperature, and field-dependent ac susceptibility measurements, and Hall analysis, reveals the formation of a spin-cluster-like glassy magnetic phase attributed to noncollinear spin textures. Additionally, the system demonstrates a colossal anomalous Hall conductivity $[{\sigma }_{xy}^A\approx 8.6\left(7\right)\times {10}^3{\mathrm{\Omega }}^{-1}\mathrm{c}{\mathrm{m}}^{-1}$ at 2 K]. Detailed scaling analyzes reveal the coexistence of skew scattering and intrinsic Berry curvature contributions to the anomalous Hall effect. First-principles calculations highlight flat-band near the Fermi level, with $f$ electrons of the Gd ion contributing large intrinsic Hall response. Thus, ${\mathrm{GdTi}}_3{\mathrm{Bi}}_4$ emerges as a rare layered kagome magnet, exhibiting Berry curvature induced giant anomalous and spin texture driven Hall responses, providing a versatile platform for exploring spin texture physics and advancing low-dimensional spintronic functionalities.

We present a comprehensive investigation of the influence of Ru concentration on the lattice parameters, atomic magnetic moments, electronic structure, and magnetic anisotropy energy of the full Heusler $\mathrm{L}{2}_1$-type ${\mathrm{Mn}}_2{\mathrm{Ru}}_{1\text{−}{x}_p}\mathrm{Ga}$ alloy, where $x_p=0.0834·p$ with $p=0,\cdots ,12$. This study combines first-principles calculations with data-driven techniques from artificial intelligence, specifically principal component analysis, to reveal trends and correlations across multiple structural, magnetic, and electronic descriptors. For each composition, a set of inequivalent atomic configurations was fully optimized. Structurally, the relaxed lattices exhibit anisotropic expansion, with a pronounced elongation of the out-of-plane lattice parameter ($c$) relative to the in-plane lattice vectors, which promotes the development of perpendicular magnetic anisotropy. In addition, our analysis demonstrates that the spatial arrangement of Ru vacancies, forming correlated vacancy pairs and clusters, plays a key role in stabilizing the out-of-plane magnetization by breaking local lattice symmetry and enhancing spin-orbit coupling. As a result, an out-of-plane easy axis emerges at intermediate Ru concentrations (25–58%), whereas low and high Ru levels favor an in-plane orientation or even vanishing anisotropy. The half-metallic character is also modulated by Ru content, appearing selectively at both ends of the composition range. Additionally, the ferrimagnetic coupling between Mn(4a) and Mn(4c) sublattices leads to nearly compensated magnetic moments below 50% Ru content, with a net moment close to zero around 30%. These findings open a pathway toward the design of tunable spintronic materials with co-optimized perpendicular magnetic anisotropy and half-metallicity, making ${\mathrm{Mn}}_2\mathrm{RuGa}$ a promising candidate for magnetic tunnel junctions, magnetoresistive random-access memory devices, and high-density magnetic storage applications.

The stability and magnonic properties of double-layered antiferromagnets are investigated using two model systems, a linear chain (LC) and a more complex chain of railroad trestle (RT) geometry, and the results are confronted with properties of the real material CrN. The spin-paired order ($\cdots ++--\cdots$) in LC requires alternating ferromagnetic and antiferromagnetic (AFM) exchanges, whereas in RT, an analogous order remains stable even when all interactions are AFM within certain analytical constraints. The rock-salt structure of CrN evokes clear magnetic frustration since Cr atoms in a face-centered cubic lattice form links to twelve nearest neighbors (NNs), all equivalent and AFM. Nonetheless, the magnetostructural transition to an orthorhombically distorted phase below $T_{\text{N}}=287\mathrm{K}$ leads to four different NN Cr–Cr distances and, consequently, to a large diversification of the exchange strength, which suppresses the frustration and allows for stable double-layered AFM order of CrN. This behavior originates from a competition at each NN link between Cr–Cr direct exchange and 90° Cr–N–Cr superexchange, both exhibiting specific power-law dependences on the interatomic distance. Finally, based on the ab initio calculated exchange parameters, the magnon spectrum and temperature evolution of ordered magnetic moments are derived.

Thermodynamic and electrical transport properties are reported for single crystals of the trigonal ${\mathrm{GdAl}}_2{\mathrm{Ge}}_2$, where complex antiferromagnetic ordering is seen at $T_{N1}$ = 23.3 K and $T_{N2}$ = 20.8 K and a rich phase diagram is revealed under applied magnetic fields. Angle-resolved photoemission spectroscopy (ARPES) measurements provide insights into this behavior by revealing a threefold symmetric Fermi surface that reflects the trigonal space-group symmetry. This promotes competing long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions between localized magnetic moments and is associated with the appearance of fine tuned ordered states. This is accompanied by intrinsic null orbital angular momentum ($L$ $=$ 0 for trivalent Gd), which yields Heisenberg spins and ensures that the symmetry of the Fermi surface dominates the magnetic behavior over wide temperature ranges. Comparisons are made to related triangular-net $f$-electron materials, providing guidance for understanding their diverse behaviors.

We present a comprehensive first-principles investigation of a hypothetical cubic $Pm\overline{3}m$ phase of the ternary hydride ${\mathrm{NaAlH}}_3$, focusing on its lattice dynamics, electronic structure, and electron-phonon-mediated superconducting properties at ambient pressure. Using density functional theory and the Migdal-Eliashberg formalism, we find an exceptionally strong electron-phonon coupling ($\lambda =2.23$), resulting in a superconducting critical temperature of up to 73.7 K for a Coulomb pseudopotential ${\mu }^{*}=0.1$. Phonon dispersion calculations, complemented by ab initio molecular dynamics simulations, indicate dynamic and thermal stability within the adopted theoretical framework. The electronic structure exhibits a metallic character with substantial contributions from Al- and Na-derived states at the Fermi level. The resulting superconducting gap ratio ($2\mathrm{\Delta }\left(0\right)/k_B{T}_c\approx 4.8$) and specific heat jump ($\mathrm{\Delta }C/\gamma T_c\approx 2.2$) significantly exceed BCS weak-coupling predictions, highlighting the strong-coupling nature of superconductivity in this hypothetical phase.

We analyze the quantum states of an isolated composite system consisting of two stacked quantum Ising (SQI) subsystems, coupled by a local Hamiltonian term that preserves the ${\mathbb{Z}}_2$ symmetry of each subsystem. The coupling strength is controlled by an intercoupling parameter $w$, with $w=0$ corresponding to decoupled quantum Ising subsystems. We focus on the quantum correlations of one of the two SQI subsystems, $\mathcal{S}$, in the ground state of the global system and study their dependence on both the state of the weakly coupled complementary part $\mathcal{E}$ and the intercoupling strength. We concentrate on regimes in which $\mathcal{S}$ develops critical long-range correlations. The most interesting physical scenario arises when both SQI subsystems are critical. In particular, for identical SQI subsystems, the global system is equivalent to the quantum Ashkin-Teller model, characterized by an additional ${\mathbb{Z}}_2$ interchange symmetry between the two subsystem operators. In this limit, one-dimensional SQI systems exhibit a peculiar critical line along which the length-scale critical exponent $\nu$ varies continuously with $w$, while two-dimensional systems develop quantum multicritical behaviors characterized by an effective enlargement of the symmetry of the critical modes, from the actual discrete ${\mathbb{Z}}_2\oplus {\mathbb{Z}}_2$ symmetry to an effective continuous O(2) symmetry.

We explore topological manipulations in one spatial dimension, which are defined for a system with a global symmetry and map the system to another one with a dual symmetry. In particular, we discuss fusion category symmetries enhanced by the invariance of the actions of topological manipulations, i.e., self-$G$-alities for topological manipulations. Based on the self-$G$-ality conditions, we provide LSM-type constraints on the ground states of many-body Hamiltonians. We clarify the relationship between different enhanced symmetries and how they are further enhanced when they meet. We explore concrete lattice models for such self-$G$-alities and identify how the self-$G$-ality structures match the IR critical theories.

We discuss the quantum geometric contribution to the diffusion constant and the DC conductivity in metals and semimetals with linear Dirac dispersion. We demonstrate that, for systems with perfectly linear dispersion, there exists a clear and rigorous separation of the quantum geometric from the ordinary band velocity contributions to the diffusion constant, which turns out to be directly related to the separation of a rank two tensor into transverse and longitudinal parts. We also demonstrate that, within the self-consistent Born approximation and for Gaussian-distributed disorder, the diffusion constant of three-dimensional Dirac fermions at charge neutrality is entirely quantum geometric in origin, which is not the case for two-dimensional Dirac fermions. This is the result of an accidental perfect cancellation of the band velocity contribution in three dimensions.

We study the physics of a mobile impurity immersed in a one-dimensional topological superconductor. We discuss the phase diagram of this system obtained with exact diagonalization and Chevy-type variational Ansatz. We argue that the character of the transition from a weak to strong coupling regime depends on the phase of the host superconductor. A smooth crossover between a weakly coupled polaron and a molecular state is observed in the topological phase. In contrast, the impurity undergoes a sharp polaron-molecule transition in a topologically trivial background.

Nonlinearities in the classical Hall resistance of two-dimensional electron gases exposed to retroreflective obstacles at random positions are reported. The Hall slope develops a nonmonotonic component, which increases strongly in amplitude and shifts to larger magnetic fields as the obstacle density increases. At small magnetic fields, the relation between the longitudinal and transverse conductivity remains in qualitative agreement with the Drude-Boltzmann equations, although the characteristic timescale can no longer be interpreted as a momentum relaxation time. The corresponding Hall conductivity develops a marked minimum at a characteristic magnetic field outside the interval where the data agree qualitatively with the Drude-Boltzmann model. With the help of classical event-driven simulations, this minimum is attributed to successive retroreflections which lead to inverted transverse deflection.

Moiré quasicrystals extend the twistronics paradigm beyond crystalline order, hosting electronic properties dictated by nonperiodic symmetry. Here, we investigate the fate of the kagome lattice's defining feature, its flat band, in a moiré quasicrystal formed by a ${30}^{\circ }$-twisted bilayer. Our tight-binding model reveals that the characteristic flat band of the kagome lattice undergoes a dramatic fragmentation into multiple gapped subbands, a direct consequence of interlayer coupling and the emergent 12-fold rotational symmetry. The primary gap is robust against variations in interlayer hopping strength, while the density of states (DOS) exhibits a fractal structure, with distinctive peaks and valleys originating from band hybridization and crossings. These predictions are validated by first-principles calculations for a morié quasicrystal formed by a realistic kagome covalent organic framework, ${\mathrm{C}}_{18}{\mathrm{H}}_{12}{\mathrm{B}}_6{\mathrm{O}}_6$. Our work establishes twisted kagome bilayers as a promising platform for exploring correlated physics in quasiperiodic flat bands.

Natural circular dichroism (NCD) provides fundamental insight into molecular chirality and stereochemical environments. Extending this concept into the hard-x-ray regime enables element-specific and site-selective chiral sensitivity inaccessible to optical wavelengths. Here, we demonstrate that $1s2p$ resonant inelastic x-ray scattering (RIXS) can be used to probe NCD in the enantiomeric model compound [Co(en)${}_3]{\left({\mathrm{NO}}_3\right)}_2$. Using high-resolution detection of Co $K\alpha$ emission under circularly polarized excitation at the cobalt $1s$ pre-edge, we observe pronounced dichroic behavior directly linked to the Co-centered chirality. The RIXS-NCD signal reaches $\approx 23\%$ of the pre-edge maximum—more than twice the amplitude of the previously reported x-ray NCD signal for the same compound—and exhibits the expected angular dependence for the crystal's $P{6}_{3}22$ symmetry. Two-dimensional RIXS-NCD maps further reveal strong helicity-dependent features across both excitation and emission energies, providing a richer description of the chiral electronic structure. These results establish RIXS-NCD as a photon-in–photon-out methodology for investigating natural optical activity with elemental and orbital specificity, paving the way for future applications to complex chiral and bioinspired materials.

The Sachdev-Ye-Kitaev (SYK) model is a cornerstone in the study of quantum chaos and holographic quantum matter. Real-world implementations, however, deviate from the idealized all-to-all connectivity, raising questions about the robustness of its chaotic properties. In this work, we investigate a quadratic SYK model with distance-dependent interactions governed by a power-law decay. By analytically and numerically studying the spectral form factor (SFF), we uncover how transitions present in the single-particle limit carry over to the many-body system. Nontrivial cancellations in the one-loop contributions lead to a robustness of the SFF under a considerable reduction of the interaction range. Further suppression leads to a breakdown of perturbation theory around the infinite-range path-integral saddle and the appearance of spectral regimes, marked by a higher dip and the emergence of a secondary plateau. Our results highlight the interplay between single-particle criticality and many-body dynamics, offering insights into the quantum chaos-to-localization transition and its reflection in spectral statistics.

$\beta \text{−}{\text{TeO}}_2$ has emerged as a promising wide-band-gap semiconductor for next-generation optoelectronic devices, owing to its exceptionally high hole mobility and excellent nonlinear optical properties. However, while static characteristics are well-studied, the ultrafast dynamics of photogenerated carriers—critical for device efficiency—remain poorly understood. Here, we employ ab initio nonadiabatic molecular dynamics within a surface-hopping framework to investigate the relaxation processes of electrons and holes in $\beta \text{−}{\text{TeO}}_2$. Our simulations reveal a significant asymmetry: Hole relaxation occurs on a subpicosecond timescale (0.199 ps), an order of magnitude faster than electron relaxation (2.76 ps). This imbalance, which can limit the performance of light-emitting devices, is traced to fundamental differences in relaxation pathways. Electrons near the conduction band edge encounter sparse intermediate states, leading to weak nonadiabatic coupling and a phonon bottleneck, whereas holes benefit from dense valence-band states coupled to high-frequency phonons, facilitating rapid transitions. Furthermore, cooling to 100 K suppresses carrier dynamics due to reduced phonon excitation yet preserves the asymmetry. Our work uncovers the microscopic origins of carrier relaxation asymmetry in $\beta \text{−}{\text{TeO}}_2$ and provides a predictive framework for optimizing optoelectronic functionality through external stimuli such as temperature and pressure.

We have conducted magnetotransport measurements on samples of NiFeMnAl and $\mathrm{NiF}{\mathrm{e}}_{1.25}{\mathrm{Mn}}_{0.75}\mathrm{Al}$, both of which are ferromagnetic. The longitudinal resistivity ${\rho }_{xx}$ of both materials exhibits shallow minima at low temperatures because of enhanced electron–electron interaction quantum-interference correction effects. The variation of ${\rho }_{xx}$ with temperature is very weak, with only a 2.5% increase between 10 K and 310 K, consistent with semimetallic behavior. At 310 K, NiFeMnAl exhibits a sharp increase in ${\rho }_{xx}$. No such increase is observed in $\mathrm{NiF}{\mathrm{e}}_{1.25}{\mathrm{Mn}}_{0.75}\mathrm{Al}$. The resistivity upturn in NiFeMnAl coincides with a similarly pronounced change in the ordinary Hall coefficient, which changes sign, indicating two-carrier transport and a shift in the Fermi level, consistent with a temperature-induced Lifshitz transition. The longitudinal magnetoresistance data exhibit excellent agreement with weak-localization theory up to temperatures near room temperature. The temperature-driven sign change in the Hall coefficient is also coincident with a shift in the magnetoresistance from negative to positive, and then oscillations at higher temperature. These dramatic effects indicate multiband transport, which calculations suggest could be caused by the underlying Weyl semimetallic behavior.

We present a combined experimental and theoretical investigation of the spin dynamics in the iron-based superconductor ${\mathrm{Ba}}_{0.75}{\mathrm{K}}_{0.25}{\mathrm{Fe}}_2{\mathrm{As}}_2$. Time-of-flight inelastic neutron scattering measurements reveal the three-dimensional (3D) nature of the spin fluctuations, manifested as out-of-plane modulations of the low-energy magnetic intensity. As the energy increases, this 3D-like modulation gradually fades away, leading to a more two-dimensional (2D) profile—a clear signature of a 3D-to-2D crossover in the spin dynamics. By incorporating a realistic 3D electronic band structure derived from density functional theory (DFT), we reproduce the experimentally observed features of the spin susceptibility, including the pronounced out-of-plane modulation at low energies and its gradual evolution into a more 2D character at higher energies. The calculated susceptibility exhibits a peak at the experimental ordering wave vector ${\mathbf{q}}_{\mathrm{AFM}}=(0.5,0.5,1)$, demonstrating that the DFT-derived 3D model accurately captures the tendency toward out-of-plane antiferromagnetic (AFM) order. Notably, electronic states away from the Fermi level play a crucial role in shaping the susceptibility peak at ${\mathbf{q}}_{\mathrm{AFM}}$, highlighting the limitations of the Fermi surface nesting picture in explaining the out-of-plane AFM instability. The demonstrated agreement between experiment and theory serves as a benchmark for validating the DFT-derived model as a realistic description of the material-specific electronic structure.