We propose a model of metallic critical point which we study at $T=0$ in the large-$N$ limit. We start with two species of fermions $u_i,d_i$, each with $N$ flavors and a gas of matrix bosons $b_{ij}$ with $N^2$ components. The fermions interact with each other via the intermediate boson as $\int b_{ij}^{†}{u}_i^{†}{d}_j$. The bosons have a bare dispersion ${\varepsilon }_{\mathbf{q}}^b={\lambda }_z{\left|\mathbf{q}\right|}^z$ and we study the problem in $d$ spatial dimensions. We show that for $d=z+1,$ the electronic self-energy shows marginal Fermi liquid behavior. We first evaluate the fermionic self-energy $\mathrm{\Sigma }\left(i\omega \right)$ using the standard approximate boson self-energy $\mathrm{\Pi }(\mathbf{q},i\nu )\propto \left|\nu \right|/\left|\mathbf{q}\right|$ and find that $\mathrm{\Sigma }\left(i\omega \right)\sim \omega ln(N/|\omega \left|\right)$ which shows a much weaker dependence on $N$ when compared with similar results from non-SYK large-$N$ Ising-nematic models. Then we evaluate $\mathrm{\Sigma }\left(i\omega \right)$ again using a more precise form of $\mathrm{\Pi }(\mathbf{q},i\nu )$ which allows us to study the interplay between $N\to \infty$ limit for which $\mathrm{\Sigma }\left(i\omega \right)\sim \omega ln(1/|\omega \left|\right)$, and the $\omega \to 0$ limit where we recover $\mathrm{\Sigma }\left(i\omega \right)\sim \omega ln(N/|\omega \left|\right)$. We also use the full bosonic self-energy to obtain the correction to the bosonic-specific heat as $\frac{T}{N}ln(1/T)$. Since there are $N^2$ bosons and $N$ fermions, the bulk heat capacity for both fermions and bosons shows nearly identical functional form $NVTln(N/T)$ and $NVTln(1/T)$, respectively, for $T\to 0$. This suggests that coupling the hybridization operator $u^{†}d$ to nonrelativistic bosons for $d=3$ and relativistic bosons for $d=2$ provides a simple route to marginal Fermi liquid scaling.

We investigate the orbital-selective electronic structure of orthorhombic ${\mathrm{CsPbI}}_3$ bulk perovskite using density functional theory combined with dynamical mean-field theory. By considering realistic values of the on-site Coulomb repulsion and spin–orbit coupling, we reveal characteristic features in the spectral functions of the active Pb-$6p$ orbitals, including the formation of spin–orbit–induced low-energy bound states. Our results further demonstrate that electron doping drives a substantial reconstruction of the electronic structure, leading to Pb-orbital selectivity. These findings provide microscopic insights into the interplay between electronic plus spin–orbit interactions and doping in orthorhombic ${\mathrm{CsPbI}}_3$ crystal, offering a framework to understand its correlated electronic state.

Half-Heusler (hH) compounds are currently considered promising thermoelectric (TE) materials owing to their favorable thermopower and electrical conductivity. Accurate estimates of their TE performance are therefore highly desirable and require a detailed microscopic understanding of the mechanisms that limit carrier transport. To enable such estimations, we carry out comprehensive first-principles computations of the electron-phonon $(e-ph)$ interactions in two hH semiconductors (LiZnAs and ScAgC). Our study first investigates their electron and phonon dispersions and then examines the temperature-induced renormalization of the electronic states within the nonadiabatic Allen-Heine-Cardona formalism. We then solve the Boltzmann transport equation (BTE) both iteratively and within multiple relaxation-time approximations (RTAs) to evaluate the carrier transport properties. Phonon-limited electron and hole mobilities computed using the linearized self-energy and momentum RTAs (SERTA and MRTA) are compared with the iterative BTE (IBTE) results. The electrical transport coefficients for TE performance are subsequently evaluated under these two RTA schemes and compared with constant RTA (CRTA) results. The lattice thermal conductivity, determined from phonon-phonon interaction, is further reduced through nanostructuring. In bulk form, LiZnAs (ScAgC) attains a maximum figure of merit $zT$ of $\sim 1.05$ (0.78) at 900 K for an electron concentration of ${10}^{18}$ $\left({10}^{19}\right)$ ${\mathrm{cm}}^{-3}$ under the MRTA. For a 20-nm nanostructured sample, the corresponding $zT$ increase to $\sim 1.53$ (1.0). The remarkably high $zT$ achieved through inherently present phonon-induced electron scattering effects, combined with grain-boundary engineering, opens a promising path for discovering highly efficient and accurate next-generation hH TEs.

Layered van der Waals material, $1T-\mathrm{TaS}{\mathrm{e}}_2$ in its star-of-David charge density wave (CDW) phase has attracted significant research interest with several unresolved issues. The current study addresses these issues for monolayer and bilayer $1T-\mathrm{TaS}{\mathrm{e}}_2$ from a perspective of combined intra- and interlayer (quasi)bonding interactions: namely, the $p$-orbital mediated intra- and interlayer d-d orbital interactions, and the interlayer interaction is quasibonding (QB) in nature, mediated by the p-p orbital interaction across adjacent layers. For the CDW phase, within a monolayer, the d-d interaction between supercells is small and leads to the formation of a narrow half-filled single band, in which a small spin-splitting gap of 0.11 eV is exhibited. From monolayer to bilayer, the interlayer interaction gives an energy splitting of 0.5 eV, which is larger than the spin-splitting gap, and hence a transition from spin-polarized insulator to non-spin-polarized insulator occurs. Moreover, we find that the interlayer interaction is multilevel in nature, namely, the bandedge of bilayer is derived from not only the energy level close to Fermi level but also correlated to a deep level with the same orbital character. The interlayer QB interaction also affects the relative stability of different interlayer-stacking configurations. This study provides an intra- and interlayer (quasi)bonding perspective for understanding the electronic structure and stability of the CDW phase monolayer and bilayers, and hence help broaden the understanding of CDW materials.

Significant progress in manipulating heat diffusion has been achieved with the advent of non-Hermitian physics and topology. However, previous studies on diffusive systems have primarily concentrated on isolated cases, where fields decay exponentially over time. In practical scenarios, systems inevitably interact with external environments, making it essential to study their responses to external heat signals. This, in turn, relies on analyzing the scattering behavior of these signals. In our work, we experimentally realize thermal scattering in a diffusive anti-parity-time (APT) system. We define key parameters of the temperature field—amplitude, phase, and chirality—and reveal that the scattering symmetry of the APT diffusive system only arises when temperature signals with different chiralities interact. Such mechanism is induced by the channel's intrinsic time-reversal antisymmetry (anti-T symmetry), which gives rise to unique dispersion properties in diffusive systems, where positive and negative frequencies are inequivalent, corresponding to different chiralities. Our findings therefore highlight the pivotal role of scattering channels in dictating the symmetry and phase transitions of non-Hermitian systems, and our work provides an experimental platform to observe and control these strongly dissipative phenomena.

A quantum mechanical Maxwell demon is proposed in a quantum dot setting. The demon avoids continuous-measurement-induced decoherence by exploiting an undetailed charge detector. The control of coherent tunneling via Landau-Zener-Stückelberg-Majorana driving allows for efficient feedback operations with no work invested. The local violation of the second law achieves simultaneous power generation and cooling. We discuss the response current fluctuations, and the demon backaction derived from failures, finding optimal performance in the nonadiabatic regime.

We study near-field radiative transfer of energy, angular momentum, and linear momentum between a nanoparticle and a plate consisting of magnetic Weyl semimetals, and demonstrate that these can be efficiently tuned by a relative angle between the Weyl node separations. This tunability originates from the coupling between the particle-induced rotational Poynting vector and the nonreciprocal surface plasmon polaritons supported by the plate. Remarkably, we uncover a counterintuitive regime in which both energy and angular momentum transfer are maximized when the Weyl node separations are antiparallel rather than parallel. This arises from optimal mode matching between the rotation direction of the particle's circular heat flux and the propagation direction of the surface plasmon polaritons in the antiparallel configuration.

Non-Markovian $1/f$ noise is a major source of decoherence in superconducting qubits, yet its low-frequency nature poses a significant challenge for accurate simulation. Here, we develop a hierarchical equations of motion (HEOM) framework that enables efficient and reliable modeling of qubit dynamics and gate operations under $1/f$ noise. Using this approach, we first show that perturbative quantum master equations fail to reproduce the correct dephasing dynamics of a qubit coupled to $1/f$ noise. We then analyze dynamical decoupling using the Carr-Purcell-Meiboom-Gill (CPMG) protocol with finite-duration pulses. The results reveal that errors accumulate linearly with parity effects in $X$-CPMG, quadratically in $Y$-CPMG, and are strongly suppressed in alternating $\mathit{XY}$ sequences. Finally, we extend the framework to simulate a two qubit cross-resonance gate and reconstruct the Pauli transfer matrix to characterize the error channels induced by $1/f$ noise. Together, these results establish HEOM as a robust and accurate method for simulating the slow non-Markovian $1/f$ noise in superconducting qubits and provide insights into error mechanisms in both single and two qubit gates.

We investigate the low-energy electronic properties of a two-dimensional topological semimetal hosted by a nonsymmorphic system with checkerboard antiferromagnetic order. Such a topological semimetallic state emerges only when the local magnetic moments align along the crystallographic direction, where the hopping is restricted to nearest neighbors and spin-orbit coupling acts between the next-nearest neighbors. We find that the quasiparticle states near Dirac or Weyl points exhibit pronounced anisotropy. Interplay of the spin-orbit coupling and magnetic moment orientation breaks the fourfold rotation symmetry, resulting in a strong directional dependence of the optical response. Using the $T$-matrix formalism, we further analyze quasiparticle interference for magnetic and nonmagnetic impurities exhibiting distinct sublattice- and spin-dependent features. The results highlight how the interplay between magnetic order and spin-orbit coupling governs anisotropic charge dynamics and impurity-induced interference, offering measurable signatures in optical and scanning tunneling spectroscopies.

Two-dimensional ferroelectric materials are widely used in advanced technologies and devices due to their unique physical properties. One of the device design strategies is the lateral heterostructures (LHS) which are easy to synthesize and precisely control. To tackle the challenge of large-scale LHS simulations, the Machine Learning Interatomic Potential (MLIP) can be utilized. Here we train the potential model specifically for monolayer GeTe and (Ge,Pb)Te LHS, which can respond to external electric fields. We investigate the thermal hysteresis and the dynamic properties including domain evolution during the ferroelectric phase transition of GeTe. According to the hysteresis loop under different temperatures and electric field frequencies, GeTe shows stable ferroelectric performance and tunability by electric fields. Additionally, we simulate and regulate multiple phases of the (Ge,Pb)Te LHS. With corrections for dipole interactions, the results show the relationship among the different states. Our research demonstrates that GeTe possesses good ferroelectric properties and highlights the application value of MLIP in the design and study of ferroelectric materials.

Recent neutron scattering and thermodynamic measurements suggest that Weyl electrons in the emergent Weyl semimetal SmAlSi mediate unconventional magnetic interactions and induce spiral magnetic order. In this work, we investigate the nature of these interactions by modeling long-range $f-f$ exchange mediated by itinerant $d$ electrons via the Ruderman-Kittel-Kasuya-Yosida mechanism, employing a material-specific tight-binding Hamiltonian obtained from first-principles calculations. The magnetic susceptibility is derived from the spin-spin correlation function based on the random phase approximation. Our results demonstrate that Fermi-surface nesting alone cannot account for the experimentally observed magnetic modulation at the wave vector (1/3, 1/3, 0); however, incorporating appropriate antiferromagnetic exchange interactions among the $d$ electrons yields the correct propagation vector. The spin-texture analysis reveals a configuration that is close to a cycloidal spin structure, preserving combined glide and time-reversal symmetry, and reflecting an intricate competition between inter- and intrasublattice interactions in SmAlSi.

We report inelastic neutron scattering (INS) measurements on the magnetically frustrated $S=\frac{1}{2}$ sawtooth-chain compound atacamite ${\mathrm{Cu}}_2\mathrm{Cl}{\left(\mathrm{OH}\right)}_3$ featuring inequivalent Cu(1) and Cu(2) sites. Transverse to the sawtooth chains, INS reveals two dispersive spin-wave modes and a gap of at least 0.75 meV. This behavior is rationalized within a zigzag-chain model of Cu(2) spins in an effective magnetic field of Cu(1) spins. The model is compatible with first-principles calculations and accounts for INS dispersions within linear spin-wave theory calculations. Our results reveal a unique case of an effective separation of energy scales between two differently oriented one-dimensional chains, with the zigzag-chain model being essential to fully characterize the low-energy magnetism of atacamite.

${\mathrm{GdCo}}_2{\mathrm{B}}_2$ is a member of the ${\mathrm{ThCr}}_2{\mathrm{Si}}_2$ family of compounds which exhibits good magnetocaloric properties associated with antiferromagnetic orderings in the temperature range for hydrogen liquefaction applications. As antiferromagnetic compounds typically do not exhibit a large magnetocaloric effect, understanding the magnetic orderings in ${\mathrm{GdCo}}_2{\mathrm{B}}_2$ could help uncover more magnetocaloric compounds that rely on antiferromagnetic ordering. ${\mathrm{GdCo}}_2{\mathrm{B}}_2$ exhibits four antiferromagnetic phase transitions at 22 K, 18.5 K, 13 K, and 7 K. Due to the difficulty of conducting neutron diffraction measurements on compounds containing affordable natural Gd, the microscopic magnetic structures have so far not been investigated. In this study, by using high energy neutrons and devising special sample preparations for lower energy neutrons, powder neutron diffraction patterns of ${\mathrm{GdCo}}_2{\mathrm{B}}_2$ have successfully been measured. A long-period incommensurate magnetic ordering with ${\mathit{k}}_1=\left(0.053100\right)$ was seen at 20 K. The propagation vector of the incommensurate structure shifted to ${\mathit{k}}_1=\left(0.07100\right)$ at 16 K, and an additional $\mathit{k}=\left(000\right)$ ferromagnetic component was observed. At 10 K, two incommensurate propagation vectors of ${\mathit{k}}_1=\left(0.073100\right)$ and ${\mathit{k}}_2=\left(0.07310.07310\right)$, which shifted to ${\mathit{k}}_1=\left(0.074100\right)$ and ${\mathit{k}}_2=\left(0.07410.07410\right)$ at 6 K, were observed to coexist. By considering only the ${\mathit{k}}_1$-modulation, two possible magnetic structures below 10 K are reported to describe the data, either $\mathit{ac}$-cycloid structure with constant moment at each Gd site or ellipsoidal $\mathit{ab}$-cycloid structure. Exchange interaction energy calculations indicated that the long-period antiferromagnetic ordering in ${\mathrm{GdCo}}_2{\mathrm{B}}_2$ is energetically close to the ferromagnetic state due to the strong competition between ferromagnetic and antiferromagnetic exchange interactions, which plays an essential role for the emergence of the large magnetocaloric effect in ${\mathrm{GdCo}}_2{\mathrm{B}}_2$.

The recent discovery of high-pressure hydrides has revealed superconducting critical temperatures ($T_{\mathrm{c}}$) surpassing 200 K above 150 GPa, advancing the pursuit of room-temperature superconductivity. Although ongoing research aims to elevate the $T_{\mathrm{c}}$ in these systems further, addressing the challenges associated with their high-pressure synthesis remains an essential task. Inspired by the recent prediction of high-temperature superconductivity in $\mathrm{La}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$, we explore its isostructural counterparts $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ and $\mathrm{Th}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ using ab initio methods. Our calculations reveal that chemical substitution of La with Ce or Th substantially lowers the stabilization pressure. Specifically, the Ce and Th variants are found to be thermodynamically stable above 185 and 200 GPa, respectively, compared to 242 GPa for $\mathrm{La}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$. Harmonic calculations yield $T_{\mathrm{c}}$ values of 204 K at 200 GPa for $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ and 230 K at 210 GPa for $\mathrm{Th}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$. Notably, when anharmonic effects are included for $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$, it reduces its dynamic stability pressure to 100 GPa while retaining a high $T_{\mathrm{c}}$ of 216 K. The crucial synergy between chemical precompression mediated by delocalized $f$ electrons, which substantially reduces the stabilization pressure, and the inclusion of anharmonic quantum nuclear effects, which provides a more precise physical description leading to a further dramatic reduction of the dynamic stability pressure, is essential for accurately predicting the high-$T_{\mathrm{c}}$ superconductivity in these hydrides at experimentally relevant pressures. Our results establish a foundation for targeted exploration of high-$T_{\mathrm{c}}$ superconductors under milder experimental conditions.

The cooperative effect of Rashba spin-orbit coupling (SOC) and Coulomb attraction in stabilizing topological spin-triplet excitonic condensates (ECs) in two-dimensional electron-hole systems in external magnetic field is investigated by using an unrestricted Hartree-Fock approach combined with the random-phase approximation. At weak electron-hole Coulomb interaction, the intraband Rashba SOC induces spin-momentum locking and topological semimetal behavior, while stronger interaction stabilizes spin-triplet ECs. Increasing the valence-band SOC drives a transition from a topologically trivial EC with coexisting spin-up and spin-down components to a topological spin-up EC only with quantized Chern number $C=2$. The dynamical excitonic susceptibility reveals a soft spin-up triplet mode acting as the precursor of the condensate. These results establish a microscopic mechanism for Rashba SOC-induced topological ECs and suggest realistic situations for their realization in noncentrosymmetric Janus transition-metal dichalcogenides and twisted van der Waals heterostructures.

The low-temperature metallic phase of $1\mathrm{T}\text{−}{\mathrm{TaS}}_2$ may originate from the current- and voltage-driven destabilization of the commensurate charge density wave in a strongly correlated Mott-insulator, alongside the robust yet rarely realized influence of intrinsic electronic distortions. Electrical pulse-driven transport, combined with the second harmonic response, reveals abrupt switching, negative differential resistance, and multiscale domain-wall reorganization. The free-energy analysis identifies a critical order parameter threshold for the Mott-metal transition, with scaling exponents ($\beta \approx 1.3$) consistent with two-dimensional percolation. The sparse limit fractal dimension $D_f\approx 0.3$ at 10 K, rising to $\approx 0.9$ at 300 K, reflects the hierarchical evolution of the conductive pathways throughout the temperature. These findings establish a direct connection between fractal percolation, pulse-induced instabilities, and correlated electron transport, offering a framework for controlled access to nonequilibrium phase transitions in low-dimensional quantum materials.

In this work, we investigate the physical origin of ferroelectricity in monolayer ${\mathrm{Bi}}_2{\mathrm{TeO}}_5$ using first-principles theoretical approaches. It is revealed that the room-temperature ferroelectric order arises from the cooperative interplay between strong individual dipoles and moderate interdipole interactions. Based on the first-principles energy landscape, a phenomenological model is constructed to predict the temperature-dependent phase transition behavior via Monte Carlo simulations, in agreement with experimental observations. The finite-temperature results further indicate a small ferroelectric domain size, consistent with the moderate strength and relatively localized effective range of the interdipole interactions. Additionally, the experimentally observed antiferroelectriclike order induced by intercalated buffer layers is demonstrated to be a robustly pinned ${180}^{\circ }$ ferroelectric domain wall rather than a genuine antiferroelectric phase.

Motivated by the order fractionalization in the Kitaev-Kondo model, we propose an exactly solvable spin-charge ladder model to study order fractionalization with discrete symmetry. The spin-charge ladder is composed of a spin chain and a superconducting wire coupled via an Ising-type interaction, and we obtain the exact solution in the flat band limit. The exact solution reveals the ${\mathbb{Z}}_2$ order fractionalization with dual symmetry breaking and intertwined order parameters. We investigate the topological phase transition of the spin-charge ladder via the spectral chiral index, and we identify the correlated topological superconductor phase with gapped ${\mathbb{Z}}_2$ Kondo flux excitations. We demonstrate that Majorana spinons generate odd frequency pairing in the superconducting wire. We also discuss the order fractionalization from the perspective of ${\mathbb{Z}}_2$ lattice gauge theory.