This study presents a refined approach to computing the electronic structure of indium antimonide (InSb) using advanced ab initio techniques with the In and Sb $4d^{10}$ semicore electrons included in the valence states. These states are modeled using fully relativistic projector augmented waves (PAW) and optimized norm-conserving Vanderbilt (ONCV) pseudopotentials. However, standard Kohn-Sham density-functional theory (DFT) calculations with these pseudopotentials often produce nonphysical band inversions and incorrect band gaps at the $\mathrm{\Gamma }$ point because of $5p\text{−}4d$ repulsion and self-interaction errors (SIE). To resolve these issues, we apply a combination of hybrid Heyd-Scuseria-Ernzerhof (HSE) exchange-correlation (XC) functionals, many-body perturbation theory (MBPT) via quasiparticle $G_0{W}_0$, and $\mathrm{DFT}+U$, significantly improving the accuracy of the band structure over previous studies. A Bayesian optimization framework is used to refine key parameters, including the inverse screening length $\left(\mathit{\mu }\right)$ and Hartree-Fock (HF) exchange fraction $\left(\mathit{\alpha }\right)$ in HSE-based XC functionals, as well as the Hubbard $\mathit{U}$ parameters in $\mathrm{DFT}+U$, leading to significantly improved band structure predictions. This approach yields highly precise band gaps, bulk moduli, effective masses, Luttinger parameters, valence bandwidth, and $4d$ band positions, achieving unprecedented agreement with experimental data. The resulting model resolves a long-standing incomplete description of InSb's electronic band structure and provides a transferable computational framework for accurate electronic structure predictions across diverse material systems, offering valuable insights for future electronic, optoelectronic, and quantum applications.

The construction of Wannier functions from Bloch orbitals offers a unitary freedom that can be exploited to yield Wannier functions with advantageous properties. Minimizing the spatial variance is a well-known choice; another, previously proposed for Wannier functions constructed from the occupied Bloch manifold, minimizes a weighted sum of spatial and energy variance. Departing from all previous work, we extend dual localization to include both valence and conduction bands together. Near the Fermi energy, these dually localized Wannier functions yield frontier (bonding and antibonding) orbitals in bulk silicon and molecular ethylene, as well as $d$ orbital character in metallic copper. Because they are both localized and retain information about the orbital energy spectrum, dually localized Wannier functions are well suited to orbital-dependent methods that associate Wannier functions with specific energy ranges. They naturally induce fractional occupations, allowing for total energy corrections to density functional calculations.

Altermagnetism exhibits zero net magnetization and spin-splitting electronic structure. The interplay between altermagnetism and topological physics becomes an important topic in condensed matter physics. In this work, we propose that the altermagnet ${\mathrm{Ce}}_4{\mathrm{Sb}}_3$ hosts Dirac fermions and we explore this idea through first-principles calculations and tight-binding-model analysis. When subjected to an external magnetic field, the altermagnet ${\mathrm{Ce}}_4{\mathrm{Sb}}_3$ changes from an altermagnetic state to a ferromagnetic state. Accompanied by magnetic order transition, the fourfold degenerate Dirac points transit into sextuple degenerate points. Especially, the spin-orbit-coupling effect has little influence on the Dirac fermions. The topological phases in the altermagnetic state may hold the exotic spin-splitter torque and the remarkable nonlinear transport effect. Our work paves the way for exploring the interplay between altermagnetism and the nontrivial topological phase.

We demonstrate that the fidelity between two states with different Chern numbers $\mathcal{Z}=\mathrm{tr}\left\{\rho {\rho }^{\prime }\right\}$ serves as a generating theory for an effective conformal field theory (CFT) at the $(2+0)$-dimensional temporal interface. $\rho$ can be chosen to be a pure trivial insulator, and ${\rho }^{\prime }$ can be taken as a pure or dephased Chern insulator density matrix. More specifically, we obtain the following results: (1) Through evaluation of the effective central charge, stiffness, and correlation function (the “strange correlators”), we demonstrate that the fidelity between a trivial insulator and an insulator with Chern number $C=1$ maps to a CFT with effective central charge $c_{\mathrm{eff}}=1$, while the fidelity between two Chern insulators with Chern numbers $C=\pm 1$ maps to a CFT with $c_{\mathrm{eff}}=2$. (2) The density matrix of the Chern insulator becomes a quantum spin Hall insulator in the doubled Hilbert space, and the dephasing acts as an interaction between the two spin species. (3) In the limit of infinite dephasing the Chern insulator becomes a superconductor in the doubled Hilbert space, featuring the “strong-weak” U(1) spontaneous symmetry breaking. An analysis based on the Laughlin wave function and previous studies of the projected wave function of the quantum spin Hall insulator suggest this is a power-law superconductor. (4) With increasing strength of dephasing, the amplitude of the single-particle strange correlator is suppressed, while the Cooper pair strange correlator is enhanced, consistent with the trend of emerging superconductivity.

By utilizing the twisted boundary conditions in the exact diagonalization method, we investigate the single-particle spectral function of the extended Peierls-Hubbard model at both half-filling and quarter-filling. In one-dimensional (1D) interacting systems, the spin-charge separation can typically be identified in the single-particle spectral function by observing the distinct spinon and holon bands. At half-filling, starting from the pure 1D Hubbard model with the on-site interaction $U=10$, we observe that the band structure indicative of the spin-charge separation gradually transitions to four individual bands as the Peierls instability $\delta$ increases. At $U=10$ and $\delta =0.2$ where the spin-charge separation is still observable, increasing the nearest-neighbor interaction $V$ can drive the system to a charge-density-wave state when $V\gtrsim U/2$. At quarter-filling, on the other hand, the ground state of Peierls-Hubbard model manifests an antiferromagnetic Mott insulator in units of dimers. Increasing $U$ results in only a very small gap in the single-particle spectrum because even for $U=+\infty$, with the model transforming into a noninteracting half-filled dimerized tight-binding model, its gap determined by the Peierls instability $\delta$ remains small. Conversely, increasing $V$ can effectively open the single-particle gap and make the spinon and holon bands more prominent.

While conventional surface waves propagate along the surface and decay perpendicularly from the interface, the ghost surface polaritons show an oblique propagation direction with respect to the interface. Here, we have discovered topologically protected ghost surface polaritons by applying the lattice transformation optics method to gyromagnetic photonic crystals. By introducing the transformation optics method to periodic systems, we develop the lattice transformation optics method to engineer the band structures and propagation directions of the surface polaritons. We show that a simple shear transformation on the square lattice can tailor the propagation directions with ease. A reversed ghost surface polariton is discovered by setting a negative shear coefficient. Interestingly, we find the topological invariant Chern number will change sign when the orientation of the Brillouin zone flips during the transformation. Our findings open up different avenues for studying ghost surface polaritons and provide a general engineering method for periodic systems.

We investigate the energy spectrum and transport properties of a diatomic square lattice model that manifest antichiral characteristics. The emergence of antichiral edge states is primarily governed by the relative sign of the next-nearest-neighbor hopping parameters on the two sublattices. However, in finite systems, the atomic structure at the boundaries plays a crucial role in determining whether the system exhibits chiral/antichiral behavior. Using both analytical and numerical methods, we reveal the presence of antichiral edge states in ribbon geometries and emphasize the importance of atomic connectivity at the edges. Extending our analysis, we simulate various finite size geometries to identify which configuration supports antichiral behavior. The transport properties are studied in the Landauer-Büttiker approach for a Hall device with four leads. We study the transmittance coefficients, transverse (Hall), and longitudinal resistance by comparing the antichiral versus chiral situations. In particular, the antichiral case shows a vanishing Hall effect and negative longitudinal resistance. The presence of the bulk currents is proved by calculating explicitly the currents on the plaquette and the local density of states in the system with leads. Additionally, we investigate the influence of Anderson disorder on the transmittance coefficients to highlight the reduced robustness of antichiral systems.

We show asymmetry engineering as an effective approach to modulate spin-valley transport in bilayer silicene magnetic valves. Contrary to symmetric cases, our calculations for structure, magnetization, and field asymmetry engineering show that near-perfect spin and valley polarization are observed for magnetic valves in both parallel and antiparallel magnetization configurations, showing an expected tunneling magnetoresistance in the order of ${10}^5\%$. Even with the structurally and magnetically symmetric magnetic valves, antisymmetric field can induce perfect polarization for spin states while valley-unpolarized or perfect polarization for valley states while spin-unpolarized. The perfect reversal between this pair can be simply achieved by reversing the magnetization configuration of magnetic valve, providing thus attractive strategies to code the spin-valley transport in bilayer silicene for spin-valleytronics applications.

Lithium niobate (LN) metasurfaces exhibit remarkable Pockels effect-driven electro-optic tunability, enabling dynamic control of optical responses through external electric fields. When combined with their high second-order nonlinear susceptibility (${\chi }^{\left(2\right)}$), this tunability is projected into the nonlinear landscape, realizing second-harmonic generation (SHG)-dominated functionalities in integrated photonics. However, achieving deep SHG modulation in LN metasurfaces remains challenging due to LN's limited refractive index tunability under practical driving voltages. To address this, we design an air-hole-structured LN metasurface by strategically adjusting air hole positions to induce Brillouin zone folding-enabled bound states in the continuum with ultrahigh $Q$ factors ($Q>{10}^4$). Numerical simulations demonstrate a $2.59\%$ SHG conversion efficiency at $0.1\mathrm{MW}/{\mathrm{cm}}^2$ excitation and a modulation depth exceeding 0.99 under 15 V peak-to-peak voltage ($\mathrm{\Delta }{V}_{\text{pp}}$). This work establishes a compact framework for electrically tunable nonlinear optics, advancing applications in integrated quantum light sources and programmable photonic chips.

We report ground-state structures and phase transitions in $\mathrm{\Sigma }5\left[001\right]$ tilt grain boundaries (GBs) in body-centered-cubic (bcc) refractory metals Nb, Ta, Mo, and W. $\mathrm{\Sigma }5$ tilt GBs have been extensively investigated over the past several decades, with their ground-state structure—composed of kite-shaped structural units—previously thought to be well understood. By performing a rigorous GB structure search that optimizes the number of atoms in the boundary core, we predict different quasiaperiodic “split kite” phases analogous to those previously found in GBs in face-centered-cubic metals. Our results suggest that complex aperiodic phases of GBs appear to be a general phenomenon, as validated through density functional theory calculations. Moreover, the atoms in the split kite phase demonstrate distinct collective diffusion dynamics. Phase-contrast image simulations of split kites show better agreement with experimental observations, offering an alternative explanation for previous microscopy results and motivating future atomically resolved imaging of the GB structure.

$\mathrm{BaHoFe}{\mathrm{O}}_4$ is an emergent multiferroic material that exhibits unique magnetic-field ($H$)-induced ferroelectric behavior. However, the origin of this effect has remained elusive, due to the role of complex magnetic interactions in driving the system's behavior. To shed light on this, we investigated the magnetic structures of the material using neutron powder diffraction, as well as their magnetic-field-induced evolutions through a combination of complementary techniques, including magnetic measurements, Mössbauer spectroscopy, and terahertz time-domain spectroscopy. The orthorhombic crystal structure of the compound, characterized by the structural interconnection between two-dimensional Fe chains and Ho chains, remains stable upon cooling to 3 K. Below $T_{\mathrm{N}1}\approx 50$ K, ${\mathrm{Fe}}^{3+}$ spins form a collinear incommensurate spin-density-wave antiferromagnetic order with a magnetic propagation vector $k_1=(0,0,0.329)$, and the magnetic moments align along the $b$ axis. Upon further cooling, the enhancement of the $3d\text{−}4f$ exchange coupling induces long-range order in the Ho sublattice below 25 K, transforming the magnetic structure into a noncollinear commensurate antiferromagnetic order with $k_2=(0.5,0,0.5)$, with all Fe and Ho moments lying in the $ac$ plane. As the temperature decreases further, strengthening of the $4f\text{−}4f$ interactions leads to the emergence of a new commensurate antiferromagnetic order with a magnetic propagation vector $k_3=(0,0,0.5)$ at 3 K, coexisting with the antiferromagnetic structure associated with $k_2$. Similar to the incommensurate spin-density-wave structure, the Ho and Fe spins in the $k_3$ phase are oriented along the $b$ axis, with their magnetic moments modulated along the $c$ axis. The spin configuration of the Ho rings is highly sensitive to temperature and magnetic field, in contrast to the more robust spin configuration of the Fe rings. We attribute the H-induced magnetic and ferroelectric transitions in $\mathrm{BaHoFe}{\mathrm{O}}_4$ to the $H$-induced modifications in the Ho sublattice. Two metamagnetic phase transitions occur at $H_1\approx 1$ T and $H_2\approx 2$ T, associated with a spin-flop transition of the Ho magnetic sublattice. The $H$-induced canted magnetic configuration in the Ho rings above $H_1$ drives the $H$-induced ferroelectricity in $\mathrm{BaHoFe}{\mathrm{O}}_4$. This is subsequently suppressed by the growth of a higher-field paraelectric antiferromagnetic phase, characterized by a fully ferromagnetic arrangement of the Ho chains above $H_2$. Our study provides important insights into the origins of the metamagnetic phase transitions and the associated magnetoelectric effects.

Periodic metastructures (including those with a macroperiodicity) have found numerous applications within the microwave to the optical regime. The analysis and synthesis of these structures generally requires the retrieval of equivalent material parameters (EMPs). To achieve this, the well-known approach is the locally periodic approximation (LPA), which is not always valid, e.g., when the angular dependence of the scattering behavior is pronounced. Here, through semianalytical closed-form expressions, we present an alternative approach to nonlocally model metastructures supporting multiple propagating Floquet-Bloch (FB) modes. This approach can be utilized to extract spatially dispersive (nonlocal) and/or position-dependent EMPs from the scattering parameters (S-parameters). The proposed framework can determine heterogeneous angle-dependent EMPs, replicating the scattering behavior of multichannel metastructures, and it provides an intermediary tool for the design of metastructures with macroperiodicity.

We study the topological properties of Rashba spin-orbit coupling and exchange coupling induced pseudospin-1 system dice lattice under the influence of a staggered electric potential and magnetization. The band structure and topological phases of the system are investigated and compared with the pseudospin-$\frac{1}{2}$ system honeycomb lattice. Under individual influence of the staggered electric field and magnetization, the system undergoes a distinct phase transition: (i) a staggered electric potential drives the system from a quantum anomalous Hall $(C_n=2)$ to a valley polarized quantum anomalous Hall phase $(C_n=-1)$ associated with edge modes with a flip in the chirality while (ii) a staggered magnetization changes the system to a topological metal associated with unconventional antichiral edge bands, from a topological insulator. These results are further supported by calculations of the Chern phase diagrams, Hall conductance, zigzag, and armchair edge states. Our findings enhance the understanding of topological phases in the 2D pseudospin-1 system and open another platform to explore the antichiral edge states.

In this Letter, we show that the standard Dynes-Fulton analysis, commonly used to reconstruct the critical current density from interference patterns, breaks down in Josephson junctions with nonlinear phase distributions, leading to nonphysical artifacts. To address this, we developed a simple iterative reconstruction algorithm and validated it both numerically and experimentally using a planar Josephson junction model. Unlike conventional approaches based on the logarithmic Hilbert transform, the proposed method allows for incorporating prior knowledge about the system and addresses the fundamental issue of ambiguity in reconstructing the critical current density from interference patterns.

Being resilient to magnetic field, the Ising superconductor serves as an exceptional platform for studying the interplay between superconductivity and magnetism. In this Letter, we first explore the transport properties of a two-terminal graphene–Ising superconductor junction where mirage gaps are induced in the superconductor by an exchange field due to the magnetic proximity effect. We demonstrate that the chemical potential range of graphene supporting specular Andreev reflection at the interface is between the two mirage gaps and about twice the Ising spin-orbit coupling strength. This enhances the resilience of observing specular Andreev reflection against graphene potential fluctuations in experiments. We further study the Andreev interference effect based on a four-terminal junction of which two terminals consist of Ising superconductors in the presence of exchange fields. Due to the finite contribution from the spin-triplet pairing, the interference can be modulated by tuning the relative orientation of the exchange fields in addition to the traditional scheme by changing the superconducting phase difference and the chemical potential of the normal region.