The ${\mathrm{Sb}}^{3+}$ ion has attracted significant interest due to its effectiveness in boosting the optical properties of host materials. Among the interesting phenomena is the commonly observed dual-band emission, which has often been interpreted by adopting the phenomenological model that explains the dual-band emission (“ultraviolet band” and “visible band”) in Sb-doped $L{\mathrm{PO}}_4$ ($L$ = Sc, Y, Lu). However, the model for the Sb-doped $L{\mathrm{PO}}_4$ series itself has not been well understood theoretically. In this work, we employ first-principles calculations combined with group-theory analysis to clarify the underlying physical mechanism behind dual-band emission in Sb-doped $L{\mathrm{PO}}_4$ series. We demonstrate that the dual band arises from two excited-state equilibrium structures; one exhibits a relatively small distortion with respect to the ground-state equilibrium structure, while the other displays a significantly larger distortion, characteristic of an “off-center” configuration. The deviations from the ground-state configuration are dominated by two distinct vibrational modes, $b_2$ and $e$ modes, involving the Jahn-Teller effect and the pseudo-Jahn-Teller effect, respectively. Furthermore, charge transition levels and energy barriers calculated using the climbing image nudged elastic band method have aided in the understanding of the relaxation between the two excited-state configurations and the property changes across the Sc, Y, and Lu series. These insights provide a basis for understanding the exotic properties of ${\mathrm{Sb}}^{3+}$ in other hosts and may facilitate the design of optical materials in a broader range of systems involving ${\mathrm{Sb}}^{3+}$ ions.

We present a model in which a Hatsugai-Kohmoto interaction is added to a system of fermions with a Weyl point in their noninteracting dispersion relation, and analyze its behavior as a function of the chemical potential. We show that the model exhibits a Weyl-Mott point, a single isolated Green's function zero, and that this implies a non-Fermi liquid state at the border of the metallic regime and a gapped topological state for the insulating one. The Weyl-Mott point inherits the topological charge from the original Green's function pole, and is therefore naturally associated with a strongly correlated chiral anomaly.

Generic nonequilibrium many-body systems display a linear growth of bipartite entanglement entropy in time, followed by a volume law saturation. In stark contrast, the Page curve dynamics of black-hole physics shows that the entropy peaks at the Page time $t_{\text{Page}}$ and then decreases to zero. Here, we investigate such Page-like behavior of the von Neumann entropy in a model of strongly correlated spinless fermions in a typical system-environment setup and characterize the properties of the Page curve dynamics in the presence of interactions using numerically exact matrix product states methods. The two phases of growth, namely, linear growth and bending down, are shown to be separated by a nonanalyticity in the min-entropy before $t_{\text{Page}}$, which separates two different quantum phases, realized as the respective ground states of the corresponding entanglement (or equivalently, modular) Hamiltonian. We confirm and generalize, by introducing interactions, the findings of Phys. Rev. B 109, 224308 (2024) for a free spinless fermionic chain where the corresponding entanglement Hamiltonian undergoes a quantum phase transition at the point of nonanalyticity. However, in the presence of interactions, a scaling analysis gives a nonzero critical time for the nonanalyticity in the thermodynamic limit only for weak to intermediate interaction strengths, while the dynamics leading to the nonanalyticity becomes instantaneous for interactions large enough. We present a physical picture explaining these findings.

In this work we study a system of interacting fermions on a triangular lattice in the presence of an external magnetic field. We assume electrons are spin polarized and fix a density of one third, with one unit of magnetic flux per particle. The infinite density matrix renormalization group algorithm is used to compute the ground state of this generalized Fermi-Hubbard model. Increasing the strength of the nearest-neighbor repulsion, we find a first-order transition between an integer quantum Hall phase and a crystalline, generalized Wigner crystal state. The first-order nature of the phase transition is consistent with a Ginzburg-Landau argument. We expect our results to be relevant for moiré heterostructures of two-dimensional materials.

We conducted an in-depth experimental investigation into the electronic Raman scattering signature by employing energy- and power-dependent Raman spectroscopy with different laser excitations in the polycrystalline La modified $\mathrm{Ce}{\mathrm{O}}_2$ ($\mathrm{C}{\mathrm{e}}_{1–x}\mathrm{L}{\mathrm{a}}_x{\mathrm{O}}_2$) system. At a resonant energy of 2.33 eV, which approximately corresponds to the electronic transition at or from Ce $4f$ empty defect states or more specifically $F_{5/2}$ and $F_{7/2}$ in $\mathrm{C}{\mathrm{e}}_{1–x}\mathrm{L}{\mathrm{a}}_x{\mathrm{O}}_2$ samples, photoexcited electrons are stimulated from the defect state near the Fermi level. This, in turn, manifests the electronic Raman scattering signature within the Raman spectra. Consequently, under resonance conditions, the line shape ($F_{2g}$) associated with $\mathrm{Ce}-{\mathrm{O}}_8$ lattice vibrations becomes symmetric. However, under off-resonance laser excitation, it becomes asymmetric. We have elucidated this phenomenon by modeling electron-phonon interactions using the Fano model. Furthermore, we observed a nonuniform increase in the low wave number background with increasing laser power in the normalized spectra. This observation may be attributed to an increase in electronic scattering by delocalized electrons near the Fermi level, which could subsequently couple with nearby phonons. We have analyzed this effect by fitting the background of Raman spectra using a mathematical model. The major cause for the electronic Raman scattering in a $\mathrm{Ce}{\mathrm{O}}_2$-based system is the presence of unpaired $f$ electrons in the $4f$ empty defect level of $\mathrm{Ce}{\mathrm{O}}_2$-based systems. This study provides valuable insights into electronic Raman spectroscopy of oxide-based semiconductors with defects, particularly when utilizing a range of laser excitations.

We investigate the linear optical response and excitonic landscape in boron monochalcogenide ($\text{B}X, X$ = S, Se, Te) single layers using ab initio many-body perturbation theory. These 2D monochalcogenides are wide band gap semiconductors, with the valence band exhibiting a quasiflat caldera-shaped dispersion in BS and BSe sheets, associated with strong van Hove singularities at the Fermi level in the density of states, an electronic feature that plays a crucial role in the emergence of strong excitonic effects. By solving the Bethe-Salpeter equation on top of $G_0{W}_0$ quasiparticle energies, our results reveal that bound excitons arise from direct optical transitions between the highest occupied band and the lowest unoccupied band along the $\mathrm{\Gamma }-M$ and $\mathrm{\Gamma }-K$ paths. Additionally, in BS and BSe monolayers, we identify excitons that are bright for in-plane polarized incident light while becoming dark for out-of-plane polarization, and other excitons with the opposite behavior. The optical selection rules are described using group-theory analysis of wave-function symmetries, determining whether optical transitions are dipole allowed or forbidden. Furthermore, exciton radiative lifetimes are estimated to range from 0.2 ns to 1.6 ns at room temperature, while exciton binding energies are significantly high, ranging from 0.6 eV to 1.2 eV for both indirect ground-state excitons and zero-momentum direct excitons. Finally, the strong electron-hole interactions in these materials lead to the formation of tightly bound excitons with a small radius, paving the way for excitonic Bose-Einstein condensation in $\text{B}X$ monolayers. Our study sheds light on the complex excitonic features of single-layer $\text{B}X$, emphasizing its potential for cutting-edge applications in exciton-driven optoelectronics and quantum technologies.

We investigate electron transport in a ${\mathrm{CrI}}_3/\mathrm{BAs}$ moiré superlattice-based ribbon device. In terms of the effective moiré potential model, we calculate the ribbon conductance in two-terminal or four-terminal devices and discover some unconventional transport properties. As the period of the moiré superlattice increases, the system displays multiple transport gaps corresponding to the isolated narrow subbands emerging in the system, while the miniband conductance peak and its width drop significantly. When a strong perpendicular magnetic field is applied to the planar device, the Landau levels do not emerge in the miniband but persist in the miniband gap as well as in other subgaps. The miniband conductance is very vulnerable to disorder and can even be suppressed totally by weak disorder, while electrons near the subgaps exhibit a delocalization behavior. In a four-terminal device, a weak Hall-like voltage drop is demonstrated to emerge due to the anisotropic scattering of electrons from the moiré potential.

Nonstabilizer states are a fundamental resource for universal quantum computation. However, despite broad significance in quantum computing, the emergence of many-body nonstabilizerness in interacting quantum systems remains poorly understood due to its analytical intractability. Here we show that Rydberg atom arrays provide a natural reservoir of nonstabilizerness that extends beyond single qubits and arises from quantum correlations generated by the Rydberg blockade. We demonstrate that this nonstabilizerness can be experimentally accessed using two complementary methods, either performing quench dynamics or via adiabatic ground state preparation. Using the analytical framework based on matrix product states, we explain the origin of Rydberg nonstabilizerness via a quantum circuit decomposition of the wave function.

We study the Kondo screening of a spin-1/2 magnetic impurity in a $d$-wave altermagnetic metal in the presence of cubic Rashba spin-orbit coupling (SOC) by combining the variational method and the Hirsch-Fye quantum Monte Carlo simulations. Interestingly, we find that the cubic Rashba SOC plays a dominant role in the Kondo effect when the chemical potential deviates from the band center, while the spatial symmetry of the Kondo screening cloud is solely determined by the altermagnetism. Altermagnetism has a minor influence on the density of states, which is crucial for the Kondo effect, especially away from the band center. Nevertheless, from the perspective of the Kondo screening cloud, its spatial symmetry is predominantly determined by altermagnetism. The addition of a cubic Rashba term modifies the ${\mathcal{C}}_{4z}\mathcal{T}$ symmetry of a $d$-wave altermagnet to $\mathcal{I}{\mathcal{C}}_{4z}\mathcal{T}$. Notably, this change in symmetry does not manifest in the diagonal components of the spatial Kondo screening cloud. The major contribution of cubic Rashba SOC to the spatial Kondo screening cloud is that it can induce off-diagonal correlations between local spin and conduction electron spins. In addition, we find that the spatial Kondo screening cloud decays with $1/r^3$ in space, while the indirect Ruderman-Kittel-Kasuya-Yosida interaction decays with $1/r^2$ with the coexistence of cubic Rashba SOC and altermagnetism.

Thermoelectric materials are considered as promising candidates for sustainable energy generation owing to their inherent capability of directly converting waste heat into electricity. Enhancing the thermoelectric conversion efficiency is crucial for their practical applications. Here, we study the pressure effect on the thermoelectric performance in Yb-filled ${\mathrm{CoSb}}_3$ skutterudite, a highly efficient thermoelectric material. By applying external pressure, we find the significant increase of power factor to a high value of $2.9 {\mathrm{mW}\mathrm{m}}^{-1}{\mathrm{K}}^{-2}$ at room temperature. Such an enhancement is attributed to a pressure-driven electronic phase transition, as supported from the electrical transport measurements and electronic band structure calculations. This study thus establishes a connection between thermoelectric performance and the electronic phase transition and points to a route to further increase the power factor through the introduction of the electronic phase transition in thermoelectrics.

Color centers are vital for quantum information processing, yet traditional ones often face challenges in fabrication, location, and stability. Realizing color centers in natural intrinsic defects will overcome these challenges. Here, $g-{\mathrm{C}}_3{\mathrm{N}}_4$ with natural intrinsic vacancies is identified as an excellent candidate for trapping B/C atoms to form stable color centers as qubits. B/C atoms are expected to be precisely placed at identifiable vacancies in $g-{\mathrm{C}}_3{\mathrm{N}}_4$ through scanning tunneling microscope manipulation. The vacancy sites are confirmed as the most stable adsorption positions protected by diffusion barriers from thermal diffusions. The most stable charge states are ${\mathrm{C}}_{\mathrm{V}}^{+2}/{\mathrm{B}}_{\mathrm{V}}^{+2}, {\mathrm{C}}_{\mathrm{V}}^{+1}/{\mathrm{B}}_{\mathrm{V}}^{+1}$, and ${\mathrm{C}}_{\mathrm{V}}/{\mathrm{B}}_{\mathrm{V}}$ in turn, with charge transition levels of 0.39 and 2.49 eV, respectively. Specifically, the defect levels and net spin of ${\mathrm{C}}_{\mathrm{V}}/{\mathrm{B}}_{\mathrm{V}}$ can be adjusted by charge states. The zero-phonon line (ZPL) of ${\mathrm{C}}_{\mathrm{V}}$ is 1.95 eV, close to that of the $\mathrm{N}{\mathrm{V}}^{-}$ centers in diamond, while the ZPLs of ${\mathrm{C}}_{\mathrm{V}}^{+1}, {\mathrm{C}}_{\mathrm{V}}^{+2}, {\mathrm{B}}_{\mathrm{V}}^{+1}$, and ${\mathrm{B}}_{\mathrm{V}}^{+2}$ fall within the near-infrared range, making them ideal for stable initialization and readout. The larger Debye-Waller factors (from 0.1 to 0.36) indicate sufficiently strong coherence. Furthermore, the zero-field splitting parameter and the characteristic hyperfine tensor are provided as potential fingerprints for electron paramagnetic resonance experiments.

In this paper, a lateral spin tunneling FET based on an antimonene monolayer is investigated. This transistor combines a tunneling FET (TFET) and a spin FET (SFET). The nonequilibrium Green's function along with the tight-binding approach is utilized to calculate the current. Two parallel and antiparallel magnetizations are considered for the source and drain contacts, and two parallel and antiparallel currents are obtained. The effects of the magnetic alignment in the two contacts on the electrical performance of the STFET are investigated, and the performance of these two transistors is compared. The effects of surface roughness as a source of scattering on the behavior of these two transistors are studied. In addition, magnetoresistance is studied in this transistor. The antiparallel configuration demonstrates better behavior with lower OFF-current, higher ON-OFF-ratio, and lower SS.

Structural heterogeneity has been identified as a critical factor in determining the mechanical and thermodynamic properties of glasses. However, its influence on glass formation has not been fully understood. Here we report the nanometer-scale chemical heterogeneity of Ag in a ribbon $\mathrm{C}{\mathrm{u}}_{45}\mathrm{Z}{\mathrm{r}}_{45}\mathrm{A}{\mathrm{g}}_{10}$ (at. %) metallic glass using Cs-corrected scanning transmission electron microscopy. Such heterogeneity is confirmed to occur in a $\mathrm{C}{\mathrm{u}}_{45}\mathrm{Z}{\mathrm{r}}_{45}\mathrm{A}{\mathrm{g}}_{10}$ model glass when the cooling rate is tuned below $\sim {10}^8$ K/s, as demonstrated by a hybrid Monte Carlo molecular dynamics simulation. A structural survey of ${\left(\mathrm{C}{\mathrm{u}}_{0.5}\mathrm{Z}{\mathrm{r}}_{0.5}\right)}_{100-x}\mathrm{A}{\mathrm{g}}_x$ (where $x$ ranges from 0 to 20) model glasses cooled at ${10}^6$ K/s reveals an inverse relationship between the fraction of icosahedral-like short-range order and the fractal dimensionality of chemical heterogeneity. Our findings demonstrate a significant role of fractal heterogeneity in promoting glass formation, a quantitative factor that has not been adequately addressed in prevailing theories of glass formation.

Quasiperiodic systems extend the concept of Anderson transition to quasirandom and low-dimensional realms and have garnered widespread attention. Here, we propose asymptotic quasiperiodic two-dimensional systems characterized by a sequence of rational magnetic fluxes, which have an irrational limit, and predict exotic universal wave-packet dynamics and transport phenomena associated with asymptotic quasiperiodicity (AQP). The predictions unveil a class of multiple metal-insulator transitions driven by the interplay between AQP, relaxation, and finite temperature, which further reveals a unified and profound mechanism. Specifically, all the transport phenomena, including the wave-packet dynamics, the bulk and edge transport, are unified in the universal scaling laws unveiled in the asymptotic quasiperiodic regime, which demonstrate a nontrivial asymptotic connection to quantum phases in the quasiperiodic limit. Our work enriches the universal quantum transport phenomena, adding to the basic mechanisms underlying metal-insulator transitions, and opens up an avenue to study the exotic transport physics with AQP in high dimensions.

We explore the electronic structure of high-quality bismuth sodium titanate (${\mathrm{Bi}}_{1/2}{\mathrm{Na}}_{1/2}\mathrm{Ti}{\mathrm{O}}_3$) powders through a comprehensive approach combining the maximum entropy method (MEM) and Rietveld analysis of synchrotron radiation x-ray diffraction data collected at 200 K with density functional theory (DFT) calculations. The average structure is well described in the monoclinic $\mathit{Cc}$ space group rather than in the rhombohedral $R3c$ one, which is also supported by our neutron powder diffraction analysis. The MEM and Rietveld analysis provides experimental evidence of covalent Bi–O and Na–O bonding along the monoclinic $\mathit{c}$ axis. Further insights from our DFT calculations demonstrate that Bi undergoes additional displacement along the $\mathit{c}$ axis to fulfill bonding requirements; notably, the off-centered Bi forms three short bonds with oxygen atoms (2.26–2.31 Å), considerably shorter than Na–O bonds. The deviation of spontaneous polarization (${\mathbf{P}}_{\mathrm{s}}$) from ${\left[111\right]}_{\mathrm{pc}}$ is as small as 1.2 °, and the polar distortion from the rhombohedral structure (${\mathbf{P}}_{\mathrm{s}}$ // ${\left[111\right]}_{\mathrm{pc}}$) is quite small. We conclude that the covalent Bi–O bond and the resultant ferroelectricity stem primarily from the Bi $6p-\mathrm{O}3 2p$ orbital interaction mediated through Ti $3d$.

Two-dimensional ferroelectricity has garnered significant research interest owing to its potential for enabling novel miniaturized devices. While conventional perovskite ferroelectrics inherently belong to three-dimensional structural systems, preserving robust ferroelectric properties in perovskite-derived structures down to the monolayer limit is important. In this work, we conduct first-principles calculations to systematically investigate the ferroelectricity of $\mathrm{BaTi}{\mathrm{O}}_3$ monolayer film, explicitly considering the influences of strain and electrode configuration. For a freestanding $\mathrm{BaTi}{\mathrm{O}}_3$ monolayer film with $\mathrm{Ti}{\mathrm{O}}_2$ termination, in-plane ferroelectricity along the [110] orientation is energetically favored. In the case of a $\mathrm{Ti}{\mathrm{O}}_2$-terminated $\mathrm{BaTi}{\mathrm{O}}_3$ monolayer interfaced with $\mathrm{SrRu}{\mathrm{O}}_3$ electrodes, the thermodynamically stable phase undergoes sequential transitions from an in-plane ferroelectric state to a paraelectric intermediate and then to an out-of-plane ferroelectric state, as the in-plane strain varies from tensile to compressive. We further reveal that both electrode and strain significantly modify the Ti-O bond lengths, which plays a crucial role in governing ferroelectric behavior. Besides, even when the thickness of freestanding $\mathrm{Ti}{\mathrm{O}}_2$-terminated $\mathrm{BaTi}{\mathrm{O}}_3$ film reaches eight unit cells, in-plane ferroelectricity along the [110] orientation remains energetically favored under strain-free conditions. However, the out-of-plane antiferroelectric state emerges as the thermodynamically stable state under in-plane compressive strain. Our research contributes to a more comprehensive understanding of ferroelectricity in monolayer perovskite oxides.

A Dirac semimetal with magnetic atoms as constituents delivers an interesting platform to investigate the interplay of Fermi surface (FS) topology, electron correlation, and magnetism. One such family of semimetals is $\mathrm{YbMn}P{n}_2$ ($Pn=\text{Sb},\text{Bi}$), which is being actively studied due to the intertwined spin and charge degrees of freedom. Here, we investigate the relationship between the magnetic/crystal structures and FS topology of ${\mathrm{YbMnSb}}_2$ using single crystal x-ray diffraction, neutron scattering, magnetic susceptibility, magnetotransport measurements, and complimentary density functional theory (DFT) calculations. Contrary to previous reports, the x-ray and neutron diffraction reveal that ${\mathrm{YbMnSb}}_2$ crystallizes in an orthorhombic $Pnma$ structure with a notable antiphase displacement of the magnetic Mn ions that increases in magnitude upon cooling. As a result of this orthorhombicity, first-principles DFT calculation reveals a reduced Brillouin zone and more anisotropic FS of ${\mathrm{YbMnSb}}_2$ compared to ${\mathrm{YbMnBi}}_2$. Moreover, the hole-type carrier density drops by two orders of magnitude as ${\mathrm{YbMnSb}}_2$ orders antiferromagnetically, indicating band folding in a magnetic ordered state. In addition, the Landau level fan diagram yields a nontrivial nature of the Shubnikov–de Haas quantum oscillation frequency arising from the Dirac-like Fermi pocket. These results imply that ${\mathrm{YbMnSb}}_2$ is an ideal platform to explore the interplay of subtle lattice distortion, magnetic order, and topological transport arising from relativistic quasiparticles.

Solid-state spin defects, characterized by their optical addressability and unique coherent properties, are garnering significant attention for their potential applications in quantum technologies, particularly as spin-photonic interfaces and highly sensitive sensors. This study investigates the long-term electron spin Rabi oscillations of nitrogen-vacancy (NV) centers embedded in a $6H$-SiC crystal, stimulated by optical excitation at a wavelength of 980 nm. The experimental findings were acquired through pulsed electron paramagnetic resonance (EPR) conducted at a temperature of 150 K, utilizing two microwave (MW) frequency ranges: the X band (9.6 GHz) and the W band (94 GHz). The Rabi oscillation profiles were effectively modeled using a unified set of simulation parameters across varying MW pulse powers. A comparative analysis of the data from both MW frequency ranges revealed that the primary mechanism responsible for the damping of Rabi oscillations in the NV centers ensemble (with a concentration of $C_N={10}^{17}\mathrm{c}{\mathrm{m}}^{-3}$) is attributed to the nonuniform distribution of the alternating magnetic field $B_1$ within the EPR cavity. An analytical expression that accurately describes the experimentally observed increase in the modulation frequency of Rabi oscillations has been derived. The findings presented in this article are anticipated to contribute to the assessment of fidelity in various quantum algorithms that utilize the investigated spin systems as a foundational platform.