Bound states in the continuum (BICs) and their quasibound counterparts (QBICs) have emerged as powerful tools to engineer sharp resonances and extreme field confinement in wave systems. Here, we investigate the formation and tunability of BICs and QBICs for flexural waves in thin elastic plates decorated with a one-dimensional array of pointlike resonators. By designing a diatomic unit cell and varying the relative angle of the two resonators, we achieve precise control over the coupling between the guided modes of the plate and the radiation continuum. This simple geometric tuning enables the transition from a symmetry-protected BIC at the center of the Brillouin zone to a family of high-Q QBICs at finite Bloch wave vectors. We develop an analytical multiple-scattering model to compute the transmission and reflection coefficients of a plane flexural wave interacting with the array, and we demonstrate that the resulting resonances manifest as angle-dependent Fano line shapes in the scattering spectra. Furthermore, by employing a lumped-element description of the resonators, we propose a feasible physical realization of the system and validate our theoretical predictions against full finite element simulations, obtaining excellent quantitative agreement. Our results provide both a fundamental understanding and a practical route to engineer ultranarrow resonances and elastic metasurfaces with tailored dispersion, paving the way for advanced control of flexural waves in thin plates.

First-principles based crystal structure prediction (CSP) methods have proved to be an essential tool for the discovery of new materials. However, in solids close to displacive phase transitions, which are common in ferroelectrics, thermoelectrics, charge-density wave systems, or superconducting hydrides, the ionic contribution to the free energy and lattice anharmonicity become significant, limiting the capacity of CSP techniques to determine the thermodynamic stability of competing phases. While variational methods like the stochastic self-consistent harmonic approximation (SSCHA) accurately account for anharmonic lattice dynamics ab initio, their high computational cost makes them impractical for CSP. Machine-learning interatomic potentials offer accelerated sampling of the energy landscape compared to purely first-principles approaches, but their reliance on extensive training data and limited generalization restricts practical applications. Here, we propose an iterative learning framework combining evolutionary algorithms, atomic foundation models, and SSCHA to enable CSP with anharmonic lattice dynamics. Foundation models enable robust relaxations of random structures, drastically reducing the required training data. Applied to the highly anharmonic ${\mathrm{H}}_3\mathrm{S}$ system, our framework achieves good agreement with benchmarks based on density functional theory, accurately predicting phase stability and vibrational properties from 50 to 200 GPa. In PdH, our method is capable of revealing that the true ground state of the system is the rock-salt structure even if classical crystal structure predictions favor the zincblende structure. Importantly, we find that the statistical averaging in the SSCHA reduces the error in the free energy evaluation, avoiding the need for extremely high accuracy of machine-learning potentials. This approach bridges the gap between data efficiency and predictive power, establishing a practical pathway for CSP with anharmonic lattice dynamics.

Conventional perturbation theory, developed for Hermitian matrices, is inadequate for determining the eigenvalues and eigenvectors of bosonic Bogoliubov–de Gennes (BdG) Hamiltonians, whose dynamical structure leads to a non-Hermitian generalized eigenvalue problem. Here we extend the Hellmann-Feynman perturbation theory to bosonic BdG systems and formulate a unified framework applicable to both nondegenerate and nearly degenerate cases. The method provides systematic expansions for eigenvalues, eigenstates, and effective Hamiltonians, revealing that the nearly degenerate theory emerges naturally from the nondegenerate one. A key result of this work is that the perturbative framework gives access not only to the spectrum but also to geometric quantities. In particular, we obtain fully analytical expressions for the Berry curvature, including a previously overlooked contribution arising from the transformed basis. To demonstrate the robustness of the formalism, we apply it to both a ferromagnetic honeycomb lattice and a more complex triangular-lattice antiferromagnet described by a $6\times 6$ BdG Hamiltonian with multiple magnon bands and Dirac-point degeneracies. In both systems, the resulting effective $2\times 2$ Hamiltonians accurately capture the low-energy band structure and Berry curvature, in excellent agreement with full numerical diagonalization. These results establish a versatile and broadly applicable perturbation framework for bosonic BdG systems and provide new analytical insight into the geometric and topological properties of magnonic excitations.

The interplay of collective electronic orders represents a central theme in condensed matter physics, and kagome lattices offer fertile ground for studying their competition and coexistence. Although metal-decorated two-dimensional boron kagome lattices can be stabilized, their quantum phases remain largely unexplored. Here, we report a family of inverse-sandwich monolayers, $M_2{\mathrm{B}}_3$ ($M$ = Mg, Ca, Sr, Ba), in which a boron kagome sheet is sandwiched between two alkaline earth metal layers, and identify them as charge density wave (CDW) materials. We found that the CDW in ${\mathrm{Mg}}_2{\mathrm{B}}_3$ originates from the combined effects of Fermi surface nesting and electron-phonon coupling, whereas in ${\mathrm{Ca}}_2{\mathrm{B}}_3, {\mathrm{Sr}}_2{\mathrm{B}}_3$, and ${\mathrm{Ba}}_2{\mathrm{B}}_3$, it is driven by strong electron-phonon coupling between B $\sigma$ orbitals and in-plane vibrational modes. These instabilities lead to a 2 × 2 CDW ground state in ${\mathrm{Mg}}_2{\mathrm{B}}_3$ and 3 × 3 reconstructions in the heavier analogs, all of which are suppressed at room temperature by anharmonic lattice effects. Remarkably, ${\mathrm{Mg}}_2{\mathrm{B}}_3$ hosts a coexisting 2 × 2 CDW and superconductivity with a $T{}_{\text{C}}$ of 10.6 K. Under biaxial compressive strain, superconductivity coexists with nontrivial topology in the heavier compounds. Moreover, the nearly unchanged $T{}_{\text{C}}$ between the CDW ground state and the strained kagome phase implies weak competition between CDW and superconductivity. Our results establish kagome-based boron monolayers as a promising class of materials for exploring intertwined CDW, superconducting, and topological states in two dimensions.

We study superconductivity and superfluid weight of the two-dimensional $\alpha \text{−}{\mathcal{T}}_3$ lattice with on-site asymmetries, hosting an isolated quasiflat band with tunable bandwidth via a parameter $\alpha$. Within a mean-field approximation of the attractive Hubbard model, we obtain the superconducting order parameters on the three inequivalent sublattices and show their strong dependence on $\alpha$, interaction strength, and electron filling. At quasiflat band filling, a superconducting gap opens and grows power-law fast with interaction strength, instead of the usual slow exponential growth, due to diverging density of states. We calculate the superfluid weight from linear response theory and study its band dispersion and geometric contributions. While the conventional part proportional to band derivatives is suppressed in the quasiflat band regime, the contribution dominated by the quantum metric grows linearly for small interaction strength. We further demonstrate how tuning $\alpha$ enhances the quantum metric and thus the geometric superfluid weight especially near half filling, while increasing on-site asymmetries increases the conventional contribution by broadening the quasiflat band. We obtain the Berezinskii-Kosterlitz-Thouless transition temperature and demonstrate its strong dependence and enhancement with the parameter $\alpha$. Our results establish a tunable flat band system, the $\alpha \text{−}{\mathcal{T}}_3$ lattice model, as a candidate for tunable quantum geometry and superfluid weight and as a prototype of related behavior in tunable quantum materials.

Ferroelectric switching governs the functional properties of ferroelectric perovskites. It is widely accepted that this switching depends on domain nucleation and pinning and that these processes can be controlled by the defect structure. However, an atomistic picture of the influence of one important class of defects—dislocations—on ferroelectric switching is missing. This is an important gap in knowledge as dislocations cannot be avoided at interfaces and can also be engineered by plastic deformation at high temperatures. Using atomistic simulations, we show how the cores of $\langle 100\rangle$ edge dislocations in ${\mathrm{BaTiO}}_3$ can either act as nucleation centers for ferroelectric switching or pin walls depending on the direction of the applied field. The coupling between the electric field and polarization is strongest when the field is applied parallel to the Burgers vector of the dislocation.

Tensor-network renormalization group (TNRG) is an efficient real-space renormalization group method for studying the criticality in both classical and quantum lattice systems. Exploiting symmetries of a system in a TNRG algorithm can simplify the implementation of the algorithm and can help produce correct tensor RG flows. Although a general framework for considering a global on-site symmetry has been established, it is still unclear how to incorporate a lattice symmetry in TNRG. As a first step for lattice symmetries, we propose a method to incorporate the lattice-reflection symmetry in the context of a TNRG with entanglement filtering in both two and three dimensions (2D and 3D). To achieve this, we write down a general definition of lattice-reflection symmetry in tensor-network language. Then, we introduce a transposition trick for exploiting and imposing the lattice-reflection symmetry in two basic TNRG operations: projective truncations and entanglement filtering. Using the transposition trick, the detailed algorithms of the TNRG map in both 2D and 3D are laid out, where the lattice-reflection symmetry is preserved and imposed. Finally, we demonstrate how to construct the linearization of the TNRG maps in a given lattice-reflection sector, with the help of which it becomes possible to extract scaling dimensions in each sector separately. Our work paves the way for understanding the lattice-rotation symmetry in TNRG.

The mechanisms by which isolated interacting quantum systems evade thermalization extend beyond disorder-induced many-body localization, encompassing a growing class of interaction-driven phenomena. We investigate a spin-$\frac{1}{2}$ ladder with asymmetric XY leg couplings and tunable Ising interactions on the rungs, and identify the microscopic origin of quasi many-body localization (quasi-MBL) in this setting. Through a suite of diagnostics—including entanglement dynamics, fidelity susceptibility, adiabatic gauge potential norms, level-spacing statistics, and entropy of eigenstates—we uncover a reentrant progression of dynamical regimes as the rung coupling $J_z$ is varied: integrable behavior at $J_z=0$, quantum chaos at intermediate $J_z$, and a robust nonthermal regime at strong coupling. In the latter regime, we demonstrate the emergence of a reversed quantum disentangled liquid (reversed-QDL), where the light species thermalizes while the heavy species remains localized. The strong-coupling limit further yields emergent local integrals of motion anchored in a fixed-point structure, providing a microscopic origin of the observed quasi-MBL dynamics. These results establish reversed-QDL as a distinct, disorder-free route to nonergodicity and broaden the classification of dynamical phases in quantum matter.

We determine the free energy of strongly correlated electron systems in the example of the Hubbard model by calculating the contribution of spin and charge fluctuations to the Gutzwiller approximation mean-field result. We employ the slave-boson formulation of Kotliar and Ruckenstein in its spin-rotation-invariant form in the usual continuous-time approximation of the functional integral representation, corrected by “high-frequency contributions” ($\mathrm{SRIKR}+$). In contrast to all previous attempts to calculate the fluctuation contribution to the free energy within the spin-rotation-invariant Kotliar-Ruckenstein slave-boson representation (SRIKR) scheme our result preserves the noninteracting limit. We show that the correct form of the kinetic energy renormalization is essential. The results for the ground-state energy in the paramagnetic phase are in very good agreement with state-of-the-art results obtained by methods such as density matrix embedding theory, quantum Monte Carlo, and others. The leading low-temperature behavior of the free energy allows us to extract the quasiparticle effective mass, in particular its enhancement near a continuous phase transition into an ordered state. Our work demonstrates that the $\mathrm{SRIKR}+$ method is competitive with the best available alternative methods and equips the slave-boson approach with an improved synoptic power to explore strongly correlated electron systems.

Two-terminal spintronic devices remain challenging to model under realistic operating conditions, where the interplay of complex electronic structures, correlation effects, and bias-driven nonequilibrium dynamics may significantly impact charge and spin transport. Existing ab initio methods either capture bias-dependent transport but neglect dynamical correlations or include correlations but are restricted to equilibrium or linear-response regimes. To overcome these limitations, we present a framework for steady-state quantum transport, combining density functional theory (DFT), the nonequilibrium Greens' function (NEGF) method, and dynamical mean-field theory (DMFT). The framework is then applied to Cu/Co/vacuum/Cu and an Fe/MgO/Fe tunnel junction. In Co, correlations drive a transition from Fermi-liquid to non-Fermi-liquid behavior under finite bias, due to scattering of electrons with electron-hole pairs. This leads to incoherent contributions to the conductance that are observable in scanning tunneling spectroscopy experiments. In contrast, in the Fe/MgO/Fe junction, correlation effects are weaker: Fe remains close to equilibrium even at large biases. Nevertheless, inelastic scattering can still induce partly incoherent transport that modifies the device's response to the external bias. Overall, our framework provides a route to model spintronic devices beyond single-particle descriptions, while also suggesting new interpretations of experiments.

We employed a first-principles many-body approach to investigate the linear optical and second-order nonlinear harmonic generation spectra of $n\text{−}A\mathrm{P}$ ($n=\alpha ,\beta ,\gamma$; $A=\mathrm{C},\mathrm{Si}$; $\mathrm{P}=\text{phosphorus}$) monolayers. All the monolayers exhibit energetic, dynamical, thermal, and mechanical stability. Incorporating excitonic effects leads to a pronounced enhancement in both the linear and SHG responses. The dielectric spectra show absorption capability of these monolayers in the 2–5 eV energy range, covering a broad spectral region. Among these monolayers, α-SiP was found to have the largest static second-order susceptibility values of 374 pm/V along with an extremely large SHG coefficient of 2.4 nm/V at 0.8 eV, at the $G_0{W}_0$-BSE level of theory. Also, $\beta \text{−}\mathrm{SiP}$ exhibits a prominent SHG peak at ∼2 eV, whereas γ-CP monolayer exhibits at ∼4 eV, indicating these monolayers have the potential to generate light in a broad spectral range from infrared to deep ultraviolet region, making them promising candidates for nonlinear optical SHG applications.

We present a comprehensive study of the magnetic, thermodynamic, and transport properties of single-crystalline TbRhPb, a geometrically frustrated rare-earth compound that crystallizes in the noncentrosymmetric ZrNiAl-type structure, where ${\mathrm{Tb}}^{3+}$ ions form a quasikagome arrangement in the $ab$ plane. Temperature-dependent magnetization measurements reveal two successive antiferromagnetic transitions at $T_{N1}\approx$ 21 K and $T_{N2}\approx$ 12.4 K. For $H\perp c,\chi (T$) shows two broad humps at $\approx$ 60 and 110 K due to the presence of the crystal electric field (CEF) effect. Our CEF analysis shows the 13-fold degenerate ground state of the ${\mathrm{Tb}}^{3+}$ ion split into five singlets and four doublets with an overall splitting $\approx$ 277 K. Isothermal magnetization for $H\perp c$ display two steplike metamagnetic transitions with small hysteresis, whereas no such features appear for $H\parallel c$ in the ordered state, highlighting strong magnetic anisotropy. Heat-capacity and resistivity measurements confirm the magnetic ordering and indicate gapped-magnon behavior below $T_{N2}$. The resulting magnetic field-temperature ($H-T$) phase diagram indicates a complex magnetic ground state. In addition, transport measurements show metallic behavior with low carrier density and large, anisotropic magnetoresistance. First-principles calculations identify an in-plane AFM ground state and reveal linear band crossings that form nodal-line features near the Fermi level. Together, these results suggest that TbRhPb is a promising antiferromagnetic topological semimetal candidate.

We establish the conditions under which a conservation law associated with a noninvertible operator may be realized as a symmetry in quantum physics. As established by Wigner, all quantum symmetries must be represented by either unitary or antiunitary transformations. Relinquishing an implicit assumption of invertibility, we demonstrate that the fundamental invariance of quantum transition probabilities under the application of symmetries mandates that all noninvertible symmetries may only correspond to projective unitary or antiunitary transformations, i.e., partial isometries. This extends the notion of physical states beyond conventional rays in Hilbert space to equivalence classes in an extended, gauged Hilbert space, thereby broadening the traditional understanding of symmetry transformations in quantum theory. Our generalized theorem applies irrespective of the origin of the (non)invertible symmetry, holds in arbitrary spatial dimensions, and is independent of the Hamiltonian or action. We explore its physical consequences and, using simple model systems, illustrate how the distinction between invertible and noninvertible symmetries can sometimes be tied to the choice of boundary conditions.

Cluster dynamical mean-field theory (CDMFT) with an exact diagonalization (ED) impurity solver faces exponential scaling limitations from the Hilbert space dimension. We introduce subbath CDMFT, an alternative to the conventional ED-CDMFT method in which the discrete bath is subdivided into separate subbaths, each coupled to the cluster with distinct hybridization functions. In this approach, only one subbath at a time is actively involved in ED, dramatically reducing the computational cost by replacing a single large impurity problem with multiple smaller separate ones. Our method successfully reproduces key physical properties including particle-hole symmetry and Mott physics, while allowing for an extended bath representation at a fraction of the typical computational cost.

We investigate the spectral properties of doped one-dimensional excitonic insulators. Employing matrix-product-state-based methods, we compute the single-particle spectrum and optical conductivity in a correlated two-band model. Our numerical calculation reveals the emergence of a correlation-driven in-gap branch in the doped state. The origin of the in-gap branch is examined by decomposing the propagation dynamics of a single particle, elucidating that the doping-induced branch is associated with excitonic correlations. Our demonstrations suggest that the doping-induced branch can serve as an indicator of electron-hole correlations.

Understanding orientation dependent phonon transport is essential for optimizing heat dissipation in crystalline heterostructures for advanced electronic applications. However, the intrinsic and extrinsic mechanisms governing the degree of orientation dependent interfacial thermal conductance ($G$) remain insufficiently understood. Here, we systematically elucidate the fundamental mechanisms of orientation dependent heat transport across $\mathrm{Al}/\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ interfaces based on ultrafast pump-probe thermal conductance measurements and nonequilibrium molecular dynamics (NEMD) simulations. For nonideal $\mathrm{Al}/\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ interfaces prepared by thermal evaporation or magnetron sputtering, we observe only a weak orientation dependence in $G$, while intrinsic $\mathrm{Al}/\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ interfaces reveal a strong dependence, with a conductance ratio of approximately 1.8−2.4 across different crystallographic orientations. We attribute this intrinsic orientation dependence to anisotropy in phonon group velocity, i.e., the phonon focusing effect. In contrast, we demonstrate that the suppressed orientation dependent $G$ in nonideal $\mathrm{Al}/\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ interfaces results from an ultrathin amorphous layer on $\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ surfaces prior to Al deposition. This ultrathin amorphous layer acts as an isotropic filter, masking the angular dependence of phonon transmission from $\alpha \text{−}\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ to Al, effectively obscuring the role of interfacial bonding strength. Furthermore, the weak orientation dependence persists down to 80 K, indicating that the amorphous layer strongly influences phonons transport across the entire frequency spectrum, including the low-frequency modes. This work advances the understanding of orientation dependent interfacial heat transport in nonideal metal/semiconductor interfaces, and thus is beneficial to the thermal management for crystalline heterostructures electronics devices.

We explore the emergence of topological phases in moiré ${\mathrm{MoTe}}_2/{\mathrm{WSe}}_2$ bilayer, highlighting the crucial role of spin-orbit coupling and Coulomb interactions at two holes per moiré unit cell $v=2$. Our analysis uncovers robust quantum valley Hall insulating phase and reveals that long-range interactions alone can mediate the interlayer electron tunneling, generating topologically nontrivial bands even in the absence of the corresponding single-particle hopping. Additionally, we show that in the case of band mixing terms originating both from the interaction and single-particle physics, a competition between topological states realizing $s$-wave and $(p\pm ip)\text{-wave}$ symmetries can appear. Moreover, within the considered theoretical framework, we present that by introducing a small Zeeman field, one can lift the band inversion in one of the valleys. This leads to a quantum anomalous Hall insulating state with the topological gap opening in a single valley and the other being topologically trivial.