The 100 most-cited articles in Physical review. B./Physical review. B, 2020

The traditional bulk Rashba effect predicts spin-orbit coupling induced wave-vector-dependent spin splitting between energy bands in nonmagnetic solids that lack spatial inversion symmetry. The authors show here how the violation of magnetic symmetry leads instead to a few prototypes of momentum-dependent spin splitting of energy bands that are induced by antiferromagnetism. This discovery broadens the spintronics playing field to include centrosymmetric compounds, even made of light elements with low spin-orbit coupling. Atomistic density functional calculations show that giant splitting above 200 meV is possible between top two valence bands.

Known routes to ergodicity breaking -- integrability and many-body localization -- require extensively many explicit or emergent conservation laws. Here we show that two conservation laws are sufficient to provably and robustly break ergodicity by ``shattering'' Hilbert space into exponentially many dynamically disconnected sectors. This represents a new paradigm for localization, which does not rely on disorder or energy conservation, which works in any number of spatial dimensions, and which should be realizable in near-term ultracold atom experiments.

The interplay of entanglement, measurement, and noise in near-term quantum devices may lead to novel emergent phenomena. This work presents a theoretical framework to understand collective effects in the dynamics of quantum entanglement and information, using the tools of statistical mechanics. The new effective description of generic quantum circuits lends insight into a measurement-induced phase transition in the information content of the system and points toward novel schemes to identify this transition in experiments.

A new class of quantum entanglement transitions separating phases with different entanglement entropy scaling has been observed in recent numerical studies. Despite the numerical efforts, an analytical understanding of such transitions has remained elusive. Here, the authors propose a theory for the area-law to volume-law entanglement transition in many-body systems that undergo both random unitary evolutions and projective measurements. Using the replica method, the authors map analytically this entanglement transition to an ordering transition in a classical statistical mechanics model. They derive the general entanglement scaling properties at the transition and show a solvable limit where this transition can be mapped onto two-dimensional percolation.

We numerically study the measurement-driven quantum phase transition of Haar-random quantum circuits in $1+1$ dimensions. By analyzing the tripartite mutual information we are able to make a precise estimate of the critical measurement rate ${p}_{c}=0.17(1)$. We extract estimates for the associated bulk critical exponents that are consistent with the values for percolation, as well as those for stabilizer circuits, but differ from previous estimates for the Haar-random case. Our estimates of the surface order parameter exponent appear different from those for stabilizer circuits or percolation, but we cannot definitively rule out the scenario where all exponents in the three cases match. Moreover, in the Haar case the prefactor for the entanglement entropies ${S}_{n}$ depends strongly on the R\'enyi index $n$; for stabilizer circuits and percolation this dependence is absent. Results on stabilizer circuits are used to guide our study and identify measures with weak finite-size effects. We discuss how our numerical estimates constrain theories of the transition.

We propose an efficient microscopic design procedure of electronic band structures having intrinsic spin and momentum dependences in spin-orbit-coupling free antiferromagnets. Our bottom-up design approach to creating desired spin-split and reshaped electronic band structures could result in further findings of practical spin-orbit-coupling free materials exhibiting a giant spin-dependent and/or nonreciprocal transport, magnetoelectric and elastic responses, and so on, as a consequence of such band structures. We establish a systematic guideline to construct symmetric/antisymmetric spin-split and antisymmetrically deformed spin-independent band structures in spin-orbit-coupling free systems by using two polar multipole degrees of freedom, i.e., electric and magnetic toroidal multipoles. The two polar multipoles constitute a complete set and describe arbitrary degrees of freedom in the hopping Hamiltonian, whose onsite and offsite degrees of freedom in a cluster are described as the so-called cluster and bond multipoles, respectively, and another degree of freedom connecting between…

A unique feature of non-Hermitian systems is the skin effect, for which an extensive number of boundary modes appear in the presence of boundaries. Here, the authors discover higher-order counterparts of the non-Hermitian skin effect that exhibit new boundary physics. As a prime example, the second-order skin effect in two dimensions hosts corner skin modes induced by spatial symmetry protected non-Hermitian topology, which contrasts with both the conventional skin effect and Hermitian higher-order topological phases.

Photonic crystal slabs (PCSs) are a well-studied class of devices known to support optical Fano resonances for light normally incident to the slab, useful for narrow-band filters, modulators, and nonlinear photonic devices. In shallow-etched PCSs the linewidth of the resonances is easily controlled by tuning the etching depth. This design strength comes at the cost of large device footprints due to the poor in-plane localization of optical energy. In fully-etched PCSs realized in high-index-contrast material systems, the in-plane localization is greatly improved, but the command over linewidth suffers. This disadvantage in fully-etched PCSs, also known as high contrast gratings (HCGs), can be overcome by accessing symmetry-protected bound states in the continuum (BICs). By perturbing an HCG, the BIC may be excited from the free space with quality factor showing an inverse squared dependence on the magnitude of the perturbation, while inheriting the excellent in-plane localization of their unperturbed counterparts. Here, we report an exhaustive catalog of the selection rules (if and…

The intense recent research on skyrmions has focused on multilayers of classical magnetic materials, such as Co, CoFeB, or Fe. Here, the authors explore skyrmions in van der Waals bi-dimensional magnets, a new type of magnetic material in the broad family of 2D materials that contains graphene. Using $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ and Monte Carlo calculations, they demonstrate that skyrmions should exist in the so-called Janus transition metal dichalcogenides. The temperature and magnetic field range for observation of skyrmions are also predicted, as a guide for experimental exploration.

Enhancing the light-matter interaction in two-dimensional (2D) materials with high $Q$ resonances in photonic structures has boosted the development of optical and photonic devices. Herein we intend to build a bridge between the radiation engineering and the bound states in the continuum (BIC), and present a general method to control light absorption at critical coupling through the quasi-BIC resonance. In a single-mode, two-port system composed of graphene, coupled with silicon nanodisk metasurfaces, the maximum absorption of 0.5 can be achieved when the radiation rate of the magnetic dipole resonance equals to the dissipate loss rate of graphene. Furthermore, the absorption bandwidth can be adjusted more than two orders of magnitude, from 0.9 nm to 94 nm, by simultaneously changing the asymmetric parameter of metasurfaces, the Fermi level, and the layer number of graphene. This work reveals the essential role of BIC in radiation engineering and provides promising strategies in controlling light absorption of 2D materials for the next-generation optical and photonic devices, e.g.,…

We present a combined theoretical and experimental study of solid-state spin decoherence in an electronic spin bath, focusing specifically on ensembles of nitrogen-vacancy (NV) centers in diamond and the associated substitutional nitrogen spin bath. We perform measurements of NV spin free-induction decay (FID) times ${T}_{2}^{*}$ and spin-echo coherence times ${T}_{2}$ in 25 diamond samples with nitrogen concentrations [N] ranging from 0.01 to 300 ppm. We introduce a microscopic model and perform numerical simulations to quantitatively explain the degradation of both ${T}_{2}^{*}$ and ${T}_{2}$ over four orders of magnitude in [N]. Our analysis enables us to describe the NV ensemble spin coherence decay shapes as emerging consistently from the contribution of many individual NV centers.

Topological magnetic states are promising for ultradense memory and logic devices. Recent progress in two-dimensional magnets encourages the idea to realize topological states, such as skyrmions and merons, in freestanding monolayers. However, monolayers such as ${\mathrm{CrI}}_{3}$ lack Dzyaloshinskii-Moriya interactions (DMIs) and thus do not naturally exhibit skyrmions/merons but rather a ferromagnetic state. Here we propose the fabrication of $\mathrm{Cr}{(\mathrm{I},X)}_{3}$ Janus monolayers, in which the Cr atoms are covalently bonded to the underlying I ions and top-layer Br or Cl atoms. By performing first-principles calculations and Monte Carlo simulations, we identify strong enough DMIs, which leads to not only helical cycloid phases, but also to topologically nontrivial states, such as the intrinsic domain wall skyrmions in $\mathrm{Cr}{(\mathrm{I},\mathrm{Br})}_{3}$ and the magnetic-field-induced bimerons in $\mathrm{Cr}{(\mathrm{I},\mathrm{Cl})}_{3}$. Microscopic origins of such spin textures are revealed as well.

Motivated by analyses of the reported electrical resistivity and Hall coefficient data in the normal state, the authors propose that the parent compound of the newly discovered superconducting nickelate Nd${}_{1\ensuremath{-}x}$Sr${}_{x}$NiO${}_{2}$ is a self-doped Mott insulator, in which the low-density Nd $5d$ conduction electrons couple to localized Ni 3${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ electrons to form Kondo spin singlets at low temperature. The antiferromagnetic long-range order is suppressed and an insulator-metal transition results.

Cuprate superconductors have shaped the contemporary state of condensed matter physics. Recently, infinite-layer Nd-doped NiO${}_{2}$ nickelates have initiated a new era of unconventional superconductivity, of which this paper constitutes the first comprehensive theoretical analysis at weak and strong coupling. From a combined perspective of $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ studies, random phase approximation, and $t$-$J$ model analysis, the authors find that the infinite-layer nickelates form a $d$-wave superconductor with three-dimensional fermiological features. Several experiments are proposed to confirm these theoretical predictions.

In a recent work, new two-dimensional materials, monolayer ${\mathrm{MoSi}}_{2}{\mathrm{N}}_{4}$ and ${\mathrm{WSi}}_{2}{\mathrm{N}}_{4}$, were successfully synthesized in experiment, and several other monolayer materials with a similar structure, such as ${\mathrm{MoSi}}_{2}{\mathrm{As}}_{4}$, were predicted [Hong et al., Science 369, 670 (2020)]. Here, based on first-principles calculations and theoretical analysis, we investigate the electronic and optical properties of monolayer ${\mathrm{MoSi}}_{2}{\mathrm{N}}_{4}, {\mathrm{WSi}}_{2}{\mathrm{N}}_{4}$, and ${\mathrm{MoSi}}_{2}{\mathrm{As}}_{4}$. We show that these materials are semiconductors, with a pair of Dirac-type valleys located at the corners of the hexagonal Brillouin zone. Due to the broken inversion symmetry and the effect of spin-orbit coupling, the valley fermions manifest spin-valley coupling, valley-contrasting Berry curvature, and valley-selective optical circular dichroism. We also construct the low-energy effective model for the valleys, calculate the spin Hall conductivity and the permittivity, and investigate…

A major obstacle to reaching the wide applications of valleytronics operations is the lack of suitable anomalous valley Hall (AVH) materials, which should be easily fabricated and exhibit spontaneous valley polarization. Here, we identify an excellent two-dimensional AVH material, namely single-layer $\mathrm{N}{\mathrm{b}}_{3}{\mathrm{I}}_{8}$, based on first principles. Single-layer $\mathrm{N}{\mathrm{b}}_{3}{\mathrm{I}}_{8}$ is a robust ferromagnetic semiconductor with a moderate band gap. More importantly, due to the intrinsic breakings of both time-reversal symmetry and inversion symmetry, it exhibits the long-sought spontaneous valley polarization, without requiring any external tuning. Spontaneous valley polarization can reach as large as 107 meV, which is beneficial for practical operations. Furthermore, the experimental exfoliation of single-layer $\mathrm{N}{\mathrm{b}}_{3}{\mathrm{I}}_{8}$ is highly feasible as the stable layered bulk phase exists. Our findings provide an ideal platform for exploring the AVH effect and future valleytronic applications.

We develop a Markovian master equation in the Lindblad form that enables the efficient study of a wide range of open quantum many-body systems that would be inaccessible with existing methods. The validity of the master equation is based entirely on properties of the bath and the system-bath coupling, without any requirements on the level structure within the system itself. The master equation is derived using a Markov approximation that is distinct from that used in earlier approaches. We provide a rigorous bound for the error induced by this Markov approximation; the error is controlled by a dimensionless combination of intrinsic correlation and relaxation timescales of the bath. Our master equation is accurate on the same level of approximation as the Bloch-Redfield equation. In contrast to the Bloch-Redfield approach, our approach ensures preservation of the positivity of the density matrix. As a result, our method is robust, and can be solved efficiently using stochastic evolution of pure states (rather than density matrices). We discuss how our method can be applied to static…

Superconductivity in twisted bilayer graphene (TBG) has inspired fervent research to explain the origin of the phenomenon and to find whether moir\'e materials featuring flat bands offer a route to room-temperature superconductivity. Here, the authors show that TBG flat-band superconductivity relies on such quantum geometric properties of the band as its quantum metric and Berry curvature. The authors predict qualitative differences between different pairing potentials, which can be used to reveal the yet unknown pairing symmetry.

Recently, random unitary quantum circuits have received increasing attention as minimal models for the chaotic quantum many-body dynamics, since they allow for exact computation of quantities that are notoriously hard to study in traditional Hamiltonian systems. A natural question is whether nonrandom quantum circuits exist, also allowing for the derivation of analytic results. The answer is provided in this work, where the authors exhibit a class of interacting quantum circuits for which they are able to compute exactly for an infinite family of initial configurations the dynamics of correlation functions and entanglement.

Many common crystal structures can be described by a single (or very few) repeated structural motif (``monomorphous structures'') such as octahedron in cubic halide perovskites. Interestingly, recent accumulated evidence suggests that electronic structure calculations based on such macroscopically averaged monomorphous cubic ($Pm\text{\ensuremath{-}}3m$) halide perovskites obtained from x-ray diffraction, show intriguing deviations from experiment. These include systematically too small band gaps, dielectric constants dominated by the electronic, negative mixing enthalpy of alloys, and significant deviations from the measured pair distribution function. We show here that a minimization of the systems $T=0$ internal energy via density functional theory reveals a distribution of different low-symmetry local motifs, including tilting, rotations, and B-atom displacements (``polymorphous networks''). This is found only if one allows for larger-than-minimal cell size that does not geometrically exclude low symmetry motifs. As the (super) cell size increases, the energy is lowered relative…

Non-Hermitian Hamiltonians are generally sensitive to boundary conditions, and their spectra and wave functions under open boundary conditions are not necessarily predicted by the Bloch band theory for periodic boundary conditions. To elucidate such a non-Bloch feature, recent works have developed a non-Bloch band theory that works even under arbitrary boundary conditions. Here, it is demonstrated that the standard non-Bloch band theory breaks down in the symplectic class, in which non-Hermitian Hamiltonians exhibit Kramers degeneracy because of reciprocity. Instead, a modified non-Bloch band theory for the symplectic class is developed in a general manner, as well as illustrative examples. This nonstandard non-Bloch band theory underlies the ${\mathbb{Z}}_{2}$ non-Hermitian skin effect protected by reciprocity.

The correlated electronic structure of the infinite-layer compounds ${\mathrm{NdNiO}}_{2}$ and ${\mathrm{SrCuO}}_{2}$ at stoichiometry and with finite hole doping is compared. Key differences are elucidated from an advanced first-principles many-body perspective. Contrary to the charge-transfer insulating cuprate, the self-doped nickelate remains noninsulating even for large interaction strength, though the Ni-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ spectral weight is also gapped in that limit. Hybridization between $\mathrm{Ni}(3d)$ and $\mathrm{Nd}(5d)$ is crucial for the appearance of the self-doping band. Upon realistic hole doping, ${\mathrm{Sr}}_{1\ensuremath{-}y}{\mathrm{CuO}}_{2}$ shows the expected mixed oxygen-Cu-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ (Zhang-Rice) states at low energy. In the case of ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{NiO}}_{2}$, the self-doping band is shifted to higher energies and a doping-dependent ${d}_{{z}^{2}}$-versus-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ competition on Ni is revealed. The absence of prominent Zhang-Rice physics in…

Topological phases have recently witnessed rapid progress in non-Hermitian systems. Here we study a one-dimensional non-Hermitian Aubry-Andr\'e-Harper (AAH) model with imaginary periodic or quasiperiodic modulations. We demonstrate that the non-Hermitian off-diagonal AAH models can host zero-energy modes at the edges. In contrast to the Hermitian case, the zero-energy mode can be localized only at one edge. Such a topological phase corresponds to the existence of a quarter winding number defined by eigenenergy in momentum space. We further find the coexistence of a zero-energy mode located only at one edge and topological nonzero-energy edge modes characterized by a generalized Bott index. In the incommensurate case, a topological non-Hermitian quasicrystal is predicted where all bulk states and two topological edge states are localized at one edge. Such topological edge modes are protected by the generalized Bott index. Finally, we propose an experimental scheme to realize these non-Hermitian models in electric circuits. Our findings add another direction for exploring topological…

We study disorder-induced ergodicity breaking transition in high-energy eigenstates of interacting spin-1/2 chains. Using exact diagonalization, we introduce a cost function approach to quantitatively compare different scenarios for the eigenstate transition. We study ergodicity indicators such as the eigenstate entanglement entropy and the spectral level spacing ratio, and we consistently find that an (infinite-order) Berezinskii-Kosterlitz-Thouless transition yields a lower cost function when compared to a finite-order transition. Interestingly, we observe that the ergodicity breaking transition in systems studied by exact diagonalization (with around 20 lattice sites) takes place at disorder values lower than those reported in previous works. As a consequence, the crossing point in finite systems exhibits nearly thermal properties, i.e., ergodicity indicators at the transition are close to the random matrix theory predictions.

A topological insulator can be converted to an axion insulator when time reversal symmetry is broken, which leads to the opening of a gap in the Dirac surface state. Recently, MnBi${}_{2}$Te${}_{4}$ was predicted to host such a state upon antiferromagnetic ordering. Collecting and analyzing very detailed photoemission data, the authors demonstrate that this does not occur and that the Dirac surface state remains gapless well below the N\'eel temperature. Most likely, this is due to the complexity of the magnetic ordering at the surface. The quest for the discovery of an axion insulator is, therefore, still on.

Electron exchange and correlations emerging from the coupling between ionic vibrations and electrons are addressed. Spin-dependent electron-phonon coupling originates from the spin-orbit interaction, and it is shown that such electron-phonon coupling introduces exchange splitting between the spin channels in the structure. By application of these results to a model for a chiral molecular structure mounted between metallic leads, the chiral-induced spin selectivity is found to become several tens of percent using experimentally feasible parameters.

We investigate entanglement phase transitions from volume-law to area-law entanglement in a quantum many-body state under continuous position measurement on the basis of the quantum trajectory approach. We find the signatures of the transitions as peak structures in the mutual information as a function of measurement strength, as previously reported for random unitary circuits with projective measurements. At the transition points, the entanglement entropy scales logarithmically and various physical quantities scale algebraically, implying emergent conformal criticality, for both integrable and nonintegrable one-dimensional interacting Hamiltonians; however, such transitions have been argued to be absent in noninteracting regimes in some previous studies. With the aid of $U(1)$ symmetry in our model, the measurement-induced criticality exhibits a spectral signature resembling a Tomonaga-Luttinger liquid theory from symmetry-resolved entanglement. These intriguing critical phenomena are unique to steady-state regimes of the conditional dynamics at the single-trajectory level and are…

Higher-order topology realizes topologically robust corner modes as a manifestation of nontriviality. We theoretically propose non-Hermitian skin effects which stem from the second-order topology of chiral-symmetric Hermitian systems. It is found that the skin modes are localized at the corners. We demonstrate two types of second-order topological skin effects by two-dimensional intrinsic and extrinsic second-order topology. The intrinsic second-order topological skin effect is characterized topologically by bulk inversion symmetry as well as chiral symmetry. Meanwhile, the extrinsic second-order topological skin effect occurs from the topological correspondence between the edges and corners. We show that non-Hermitian skin modes emerge by using a relationship between second-order and conventional first-order topology.

We consider a collection of two level systems, such as qubits, embedded into a microwave cavity as a promising candidate for the realization of high power quantum batteries. In this perspective, the possibility to design devices where the conventional single-photon coupling is suppressed and the dominant interaction is mediated by two-photon processes is investigated, opening the way to an even further enhancement of the charging performance. By solving a Dicke model with both single- and two-photon coupling we determine the range of parameters where the latter unconventional interaction dominates the dynamics of the system leading to better performances both in the charging times and average charging power of the QB compared to the single-photon case. In addition, the scaling of the maximum stored energy, fluctuations and charging power with the finite number of qubits $N$ is inspected. While the energy and fluctuations scale linearly with $N$, the quadratic growth of the average power leads to a relevant improvement of the charging performance of quantum batteries based on this…

One of the main applications of near-term quantum computers is expected to be solving many-body quantum systems. The present study reports on extensive optimization and numerical investigation of the Variational Quantum Eigensolver method for the iconic Fermi-Hubbard model, including the effect of realistic measurements and noise. The presented optimized circuits use up to an order of magnitude fewer gates than previously reported, suggesting that quantum circuits with a gate depth substantially below 1000 could be sufficient to solve instances beyond the capacity of classical exact diagonalization.

We investigate the dynamics of two-dimensional quantum spin systems under the combined effect of random unitary gates and local projective measurements. When considering steady states, a measurement-induced transition occurs between two distinct dynamical phases, one characterized by a volume-law scaling of entanglement entropy, the other by an area law. Employing stabilizer states and Clifford random unitary gates, we numerically investigate square lattices of linear dimension up to $L=48$ for two distinct measurement protocols. For both protocols, we observe a transition point where the dominant contribution in the entanglement entropy displays multiplicative logarithmic violations to the area law. We obtain estimates of the correlation length critical exponent at the percent level; these estimates suggest universal behavior and are incompatible with the universality class of 3D percolation.

Exact ``towers'' of quantum many-body scar states are recently discovered sets of states in some many-body nonintegrable systems. They are evenly spaced in energy and do not obey the eigenstate thermalization hypothesis. Here, the authors provide a unified framework of proving several towers of states known in the literature. This sheds light on the general structure of exact scar towers, and on the specific models themselves: the 1D AKLT models, spin-1 XY model, and a spin-\textonehalf{} domain wall conserving model. In particular, they provide a simple proof for the scars in the AKLT models and discover a ``pyramid'' of exact states in the spin-\textonehalf{} model.

Strongly interacting systems with quantum many-body scars exhibit persistent fidelity oscillations when prepared in a certain class of initial states, but otherwise undergo ergodic dynamics. Previous examples of scars have interpreted the characteristic periodic dynamics in terms of the precession of a macroscopic SU(2) spin in an effective magnetic field. Here, the authors uncover a new exactly solvable example of many-body scars in a spin-\textonehalf{} model and show that the scarred dynamics in this model evades such an interpretation. This unusual coherent dynamics arises due to an emergent kinetic constraint that endows the time-evolving many-body state with constant area-law entanglement. The model studied in this work is relevant to experiments on Rydberg-atom quantum simulators in the antiblockade regime.

Certain disorder-free Hamiltonians are nonergodic due to a $s\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ $f\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}g\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$ of the Hilbert space. Here, the authors introduce the notion of ``statistically localized integrals of motion'' (SLIOM) to characterize these systems. Despite SLIOMs being nonlocal operators, they become spatially localized to subextensive regions when their expectation value is taken in typical states. These can also result in statistically localized $s\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ $z\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o$…

We revisit the $\ensuremath{\eta}$-pairing states in Hubbard models and explore their connections to quantum many-body scars to discover a universal scars mechanism. $\ensuremath{\eta}$-pairing occurs due to an algebraic structure known as a spectrum generating algebra (SGA), giving rise to equally spaced towers of eigenstates in the spectrum. We generalize the original $\ensuremath{\eta}$-pairing construction and show that several Hubbard-like models on arbitrary graphs exhibit SGAs, including ones with disorder and spin-orbit coupling. We further define a restricted spectrum generating algebra (RSGA) and give examples of perturbations to the Hubbard-like models that preserve an equally spaced tower of the original model as eigenstates. The states of the surviving tower exhibit a subthermal entanglement entropy, and we analytically obtain parameter regimes for which they lie in the bulk of the spectrum, showing that they are exact quantum many-body scars. The RSGA framework also explains the equally spaced towers of eigenstates in several well-known models of quantum scars,…

From a ferromagnetic resonance experiment on a YIG|GGG|YIG crystal, phonons are shown to be able to provide coherent long-range coupling between two magnets, which act as ``microphones'' and ``speakers'' for acoustic waves to induce feedback interference over millimeter distances. In this ``phononic spin valve'' under perpendicular magnetization, the phonons, which are circularly polarized, carry efficiently angular momentum current through a nonmagnetic dielectric. The high acoustic quality of phonon transport in garnets and the strong coupling to the magnetic order may also be useful for quantum communication.

Rare-earth polyhydrides formed under pressure are promising conventional superconductors, with the critical temperature ${T}_{c}$ in compressed ${\mathrm{LaH}}_{10}$ almost reaching room temperature. Here, we report a systematic computational investigation of the structural and superconducting properties of rare-earth (RE) polyhydrides formed under pressure across the whole lanthanide series. Analyses of the electronic and dynamical properties and electron-phonon coupling interaction for the most hydrogen-rich hydrides ${\mathrm{REH}}_{n}$ ($n=8,9,10$) that can be stabilized below 400 GPa show that enhanced ${T}_{c}$ correlates with a high density of H $s$ states and low number of RE $f$ states at the Fermi level. In addition to previously predicted and measured ${\mathrm{LaH}}_{10}$ and ${\mathrm{CeH}}_{9}$, we suggest ${\mathrm{YbH}}_{10}$ and ${\mathrm{LuH}}_{8}$ as additional potential high-${T}_{c}$ superconducters. They form a ``second island'' of high-${T}_{c}$ superconductivity amongst the late lanthanide polyhydrides, with an estimated ${T}_{c}$ of 102 K for…

Robust fractional charge localized at disclination defects has recently been found as a topological response in ${C}_{6}$-symmetric 2D topological crystalline insulators (TCIs). In this article, we thoroughly investigate the fractional charge on disclinations in ${C}_{n}$-symmetric TCIs, with or without time-reversal symmetry, and including spinless and spin-$\frac{1}{2}$ cases. We compute the fractional disclination charges from the Wannier representations in real space and use band representation theory to construct topological indices of the fractional disclination charge for all 2D TCIs that admit a (generalized) Wannier representation. We find the disclination charge is fractionalized in units of $\frac{e}{n}$ for ${C}_{n}$-symmetric TCIs, and for spin-$\frac{1}{2}$ TCIs, with additional time-reversal symmetry, the disclination charge is fractionalized in units of $\frac{2e}{n}$. We furthermore prove that with electron-electron interactions that preserve the ${C}_{n}$ symmetry and many-body bulk gap, though we can deform a TCI into another which is topologically distinct in the…

We show that lattices with higher-order topology can support corner-localized bound states in the continuum (BICs). We propose a method for the direct identification of BICs in condensed matter settings and use it to demonstrate the existence of BICs in a concrete lattice model. Although the onset for these states is given by corner-induced filling anomalies in certain topological crystalline phases, additional symmetries are required to protect the BICs from hybridizing with their degenerate bulk states. We demonstrate the protection mechanism for BICs in this model and show how breaking this mechanism transforms the BICs into higher-order topological resonances. Our work shows that topological states arising from the bulk-boundary correspondence in topological phases are more robust than previously expected, expanding the search space for crystalline topological phases to include those with boundary-localized BICs or resonances.

The equality between the spectral directional emittance and absorptance of an object under local thermodynamic equilibrium is known as Kirchhoff's law of radiation. The breakdown of Kirchhoff's law of radiation is physically allowed by breaking time reversal symmetry and can open opportunities for nonreciprocal light emitters and absorbers. Large anomalous Hall conductivity and angle recently observed in topological Weyl semimetals, particularly type-I magnetic Weyl semimetals and type-II Weyl semimetals, are expected to create large nonreciprocal electromagnetic wave propagation. In this work, we focus on type-I magnetic Weyl semimetals and show via modeling and simulation that nonreciprocal surface plasmon polaritons can result in pronounced nonreciprocity without an external magnetic field. The modeling in this work begins with a single pair of Weyl nodes, followed by a more realistic model with multiple paired Weyl nodes. Fermi-arc surface states are also taken into account through the surface conductivity. This work points to the promising applicability of topological Weyl…

Skyrmions are localized solitonic spin textures with protected topology, which are promising as information carriers in ultradense and energy-efficient logic and memory devices. Recently, magnetic skyrmions have been observed in magnetic thin films, and are stabilized by the extrinsic interfacial Dzyaloshinskii-Moriya interaction (DMI) and/or external magnetic fields. The specific effects in magnetic monolayer materials have not been thoroughly studied. Here, we investigate the intrinsic magnetic skyrmions in a family of monolayer Janus van der Waals magnets, MnSTe, MnSeTe, VSeTe, and MnSSe, by the first-principles calculations combined with the micromagnetic simulations. The monolayer Janus MnSTe, MnSeTe, and VSeTe with out-of-plane geometric asymmetry and strong spin-orbit coupling have a large intrinsic DMI, which could stabilize a sub-50-nm intrinsic skyrmions in monolayer MnSTe and MnSeTe at zero magnetic field. Whereas a monolayer VSeTe with an in-plane easy axis forms a magnetic domain rather than skyrmions. Moreover, the size and shape of skyrmions can be tuned by an…

Using first-principles calculations and micromagnetic simulations, we systematically investigate the magnetic properties of two-dimensional Janus chromium dichalcogenides ($\mathrm{Cr}X\mathrm{Te}, X=\mathrm{S}$, Se) under strain. We find that the CrSTe monolayer has high Curie temperature (${T}_{c}$) of 295 K and an out-of-plane magnetic anisotropy. The CrSeTe monolayer has large Dzyaloshinskii-Moriya interaction (DMI) which can host chiral N\'eel domain wall (DW), and under an external magnetic field, the skyrmion states can be induced. As tensile strain increases, ferromagnetic exchange coupling and perpendicular magnetic anisotropy of Janus $\mathrm{Cr}X\mathrm{Te}$ monolayers both increase significantly, and the magnitude of DMI is reduced, which results in the giant ferromagnetism enhancement. Interestingly, for CrSeTe monolayer, distinct spin textures from chiral DW to uniform ferromagnetic states are induced under tensile strain. Moreover, the diameter and density of skyrmions in CrSeTe can be tuned by the amplitude of external magnetic field and strain. These findings…

There has been much recent interest in understanding topological band theory of non-Hermitian systems. Most work has focused on the Chern number in these systems, although interesting phenomena related to an eigenvalue winding number has also been reported. Here, the authors give a complete topological classification using homotopy theory. They find that the Chern number can be reduced modulo 2 depending on the winding number, and this is interpreted in terms of braiding of Weyl points and exceptional nodal rings.

Superconductivity has recently been reported in Sr-doped NdNiO${}_{2}$ thin films. This work considers the effect of Hund coupling and crystal field splitting in a simple model system and shows that a multiorbital description of nickelate superconductors is warranted, especially in the strongly hole-doped regime. An analysis of this system, inspired by the spin-freezing theory of unconventional superconductivity, furthermore reveals that Nd${}_{0.8}$Sr${}_{0.2}$NiO${}_{2}$ has strongly enhanced local spin fluctuations due to the interplay of two spin-freezing crossovers.

Motivated by the recently observed insulating states in twisted bilayer graphene, we study the nature of the correlated insulating phases of the twisted bilayer graphene at commensurate filling fractions. We use the continuum model and project the Coulomb interaction onto the flat bands to study the ground states by using a Hartree-Fock approximation. In the absence of the hexagonal boron nitride substrate, the ground states are the intervalley coherence states at charge neutrality (filling $\ensuremath{\nu}=0$, or four electrons per moir\'e cell) and at $\ensuremath{\nu}=\ensuremath{-}1/4$ and $\ensuremath{-}1/2$ (three and two electrons per cell, respectively) and the ${C}_{2}\mathcal{T}$ symmetry-broken state at $\ensuremath{\nu}=\ensuremath{-}3/4$ (one electron per cell). The hexagonal boron nitride substrate drives the ground states at all $\ensuremath{\nu}$ into ${C}_{2}\mathcal{T}$ symmetry broken-states. Our results provide good reference points for further study of the rich correlated physics in the twisted bilayer graphene.

Transition metal dichalcogenide (TMD) bilayers have recently emerged as a robust and tunable moir\'e system for studying and designing correlated electron physics. In this Rapid Communication, by combining a large-scale first-principles calculation and continuum model approach, we provide an electronic structure theory that maps long-period TMD heterobilayer superlattices onto diatomic crystals with cations and anions. We find that the interplay between the moir\'e potential and Coulomb interaction leads to filling-dependent charge transfer between different moir\'e superlattice regions. We show that the insulating state at half filling found in recent experiments on $\mathrm{W}{\mathrm{Se}}_{2}/\mathrm{W}{\mathrm{S}}_{2}$ is a charge-transfer insulator rather than a Mott-Hubbard insulator. Our work reveals the richness of simplicity in moir\'e quantum chemistry.

Two-dimensional graphene-based van der Waals heterostructures have received considerable interest because of their intriguing characteristics compared with the constituent single-layer two-dimensional materials. Here, we investigate the interfacial characteristics, Schottky contact, and optical performance of $\mathrm{graphene}/{\mathrm{Ga}}_{2}\mathrm{SSe}$ van der Waals (vdW) heterostructure using first-principles calculations. The effects of stacking patterns, electric gating, and interlayer coupling on the interfacial properties of $\mathrm{graphene}/{\mathrm{Ga}}_{2}\mathrm{SSe}$ heterostructures are also examined. Our results demonstrate that the Dirac cone of graphene is well preserved at the $\mathrm{\ensuremath{\Gamma}}$ point in all stacking patterns due to the weak vdW interactions, which keep the heterostructures feasible such that they can be obtained in further experiments. Moreover, depending on the stacking patterns, a small band gap of about 13--17 meV opens in graphene and has a high carrier mobility, indicating that the…

The identification of deep-level defects that act as detrimental nonradiative recombination centers is critical for optimizing the optoelectronic performance of hybrid perovskites. Although extensive studies have been devoted to revealing the nature of deep-level defects in hybrid perovskites, it is still unclear what defects are responsible for the experimentally observed nonradiative recombination rates. Employing first-principles approaches, we quantitatively show that the iodine interstitial is a dominant nonradiative recombination center in methylammonium-lead iodide. This important insight points to a target for defect engineering in order to further improve the performance of hybrid perovskites.

While exploring potential superconductors in the C-S-H ternary system using first-principles crystal structure prediction methods, we uncovered a class of hydride perovskites based on the intercalation of methane into an ${\mathrm{H}}_{3}\mathrm{S}$ framework. These intriguing ${\mathrm{H}}_{3}\mathrm{S}\text{\ensuremath{-}}{\mathrm{CH}}_{4}$ structures emerge as metastable at $\ensuremath{\sim}100$ GPa. Electron-phonon coupling calculations indicate that phases with ${\mathrm{CSH}}_{7}$ stoichiometry are potential superconductors with ${T}_{c}$ values ranging from 100 K to 190 K at megabar pressures. The results are expected to guide the experimental search for new high-${T}_{c}$ superconductors, including those stable at lower pressures than previously documented superconducting hydrides such as ${\mathrm{H}}_{3}\mathrm{S}$ and ${\mathrm{LaH}}_{10}$.

We demonstrate the existence of generalized Aubry-Andr\'e self-duality in a class of non-Hermitian quasiperiodic lattices with complex potentials. From the self-duality relations, the analytical expression of mobility edges is derived. Compared to Hermitian systems, mobility edges in non-Hermitian ones not only separate localized from extended states but also indicate the coexistence of complex and real eigenenergies, making possible a topological characterization of mobility edges. An experimental scheme, based on optical pulse propagation in synthetic photonic mesh lattices, is suggested to implement a non-Hermitian quasicrystal displaying mobility edges.

Two-dimensional (2D) van der Waals (vdW) magnets have recently attracted increasing attention, as they provide a novel system for exploring 2D magnetism. However, intrinsic ferromagnetism in 2D systems has almost exclusively been observed at low temperatures, limiting their technological relevance. ${\mathrm{Fe}}_{\mathrm{N}}{\mathrm{Ge}\mathrm{Te}}_{2}$ ($N=3$, 4, and 5) systems are currently becoming the most attractive 2D vdW materials due to their relatively high Curie temperatures and large saturation magnetization. However, the nature of their complex yet intriguing magnetic behaviors is still unclear, in part due to the multiple inequivalent iron sites and iron vacancies. Here, we show evolution of magnetic ordering transitions in ${\mathrm{Fe}}_{5\ensuremath{-}x}{\mathrm{Ge}\mathrm{Te}}_{2}$ with high Curie temperature and a strong saturation magnetization using photoemission electron microscopy and transport measurements. At 275 K, the ferromagnet transitions to a ferrimagnet, and below 110 K transitions to a state with glassy clusters. These are evidenced from…

Even though electron-phonon coupling is one of the most important parameters governing material evolution after ultrafast energy deposition it remains the most unexplored one. In this work we apply the dynamical coupling approach to calculate the nonadiabatic electron-ion energy exchange in nonequilibrium solids with the electronic temperature high above the atomic one. It is implemented into the tight-binding molecular dynamics code and used to study electron-phonon coupling in various elemental metals. The approach developed is a universal scheme applicable to electronic temperatures up to a few electron volts and to arbitrary atomic configurations and dynamics. We demonstrate that the calculated electron-ion (electron-phonon) coupling parameter agrees well with the available experimental data in the high-electronic-temperature regime, validating the model. The following materials are studied here: fcc metals Al, Ca, Ni, Cu, Sr, Y, Zr, Rh, Pd, Ag, Ir, Pt, Au, and Pb; hcp metals Mg, Sc, Ti, Co, Zn, Tc, Ru, Cd, Hf, Re, and Os; bcc metals V, Cr, Fe, Nb, Mo, Ba, Ta, and W; a diamond…

The presence of quantum scars, athermal eigenstates of a many-body Hamiltonian with finite-energy density, leads to an absence of ergodicity and long-time coherent dynamics starting from initial states that have a high overlap with scars as experimentally observed in a chain of ultracold Rydberg atoms. We show, via study of a periodically driven Rydberg chain, that the drive frequency acts as a tuning parameter for several reentrant transitions between ergodic and weak ergodicity breaking regimes. The former regime shows rapid thermalization of correlation functions and absence of scars in the Floquet spectrum of the system. The latter regime, in contrast, has scars; they lead to long-time coherent dynamics of correlation functions. We provide an analytical explanation of the existence of these regimes by going beyond a high-frequency Magnus expansion and using a novel perturbative approach valid at large drive amplitudes to derive a Floquet Hamiltonian which qualitatively explains the behavior of the driven system at arbitrary frequencies. We also discuss experiments involving…

Designing high-performance piezoelectric materials based on atomic-scale calculations is highly desired in recent years, following the understanding of the structure-property relationship of state-of-the-art piezoelectric materials. Previous mesoscale simulations showed that local structural heterogeneity plays an important role in the piezoelectric property of ferroelectrics; that is, larger structural heterogeneity leads to higher piezoelectricity. In this Rapid Communication, by combining first-principles calculations and experimental characterizations, we explored the atomic-scale origin of the high piezoelectricity for samarium-doped $\mathrm{Pb}(\mathrm{M}{\mathrm{g}}_{1/3}\mathrm{N}{\mathrm{b}}_{2/3}){\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{PbTi}{\mathrm{O}}_{3}$ (PMN-PT) ceramics, which possesses the highest piezoelectric ${d}_{33}$ of $\ensuremath{\sim}1500\phantom{\rule{0.16em}{0ex}}\mathrm{pC}\phantom{\rule{0.28em}{0ex}}{\mathrm{N}}^{\ensuremath{-}1}$ among all known piezoelectric ceramics. The impacts of various dopants on local structure and piezoelectric properties…

The future technological revolution in the production of ultrafast devices lies in the control of materials that will speed-up transistors. The recent discovery of topological states of matter promises a unique opportunity to address this challenge. However, the control and diagnostics of topological materials remain hard to achieve. Here, the authors show an alternative to distinguish a topological phase by its nonlinear-light circular dichroism (CD): the asymmetry of the material-light emissivity while the topological phase is subjected to right-circularly (RCP) and left-circularly polarized (LCP) mid-infrared lasers. This CD exhibits striking distinction in a topological phase, as depicted in the schematic.

The electronic density of states (DOS) quantifies the distribution of the energy levels that can be occupied by electrons in a quasiparticle picture and is central to modern electronic structure theory. It also underpins the computation and interpretation of experimentally observable material properties such as optical absorption and electrical conductivity. We discuss the challenges inherent in the construction of a machine-learning (ML) framework aimed at predicting the DOS as a combination of local contributions that depend in turn on the geometric configuration of neighbors around each atom, using quasiparticle energy levels from density functional theory as training data. We present a challenging case study that includes configurations of silicon spanning a broad set of thermodynamic conditions, ranging from bulk structures to clusters and from semiconducting to metallic behavior. We compare different approaches to represent the DOS, and the accuracy of predicting quantities such as the Fermi level, the electron density at the Fermi level, or the band energy, either directly or…

Fully anharmonic calculations of the dielectric response of insulators require costly $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ molecular dynamics simulations. Here, the authors show that this electronic response property can be described efficiently by a deep neural network that retains the accuracy of $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ molecular dynamics. The scheme is demonstrated with calculations of the infrared absorption spectrum of liquid water at standard conditions, and of the evolution of the spectrum of crystalline ice undergoing a pressure-induced structural transformation from molecular ice VII to ionic ice X.

${\mathrm{Co}}^{2+}$ ions in an octahedral crystal field stabilize a ${j}_{\mathrm{eff}}=1/2$ ground state with an orbital degree of freedom and have been recently put forward for realizing Kitaev interactions, a prediction we have tested by investigating spin dynamics in two cobalt honeycomb lattice compounds, ${\mathrm{Na}}_{2}{\mathrm{Co}}_{2}{\mathrm{TeO}}_{6}$ and ${\mathrm{Na}}_{3}{\mathrm{Co}}_{2}{\mathrm{SbO}}_{6}$, using inelastic neutron scattering. We used linear spin wave theory to show that the magnetic spectra can be reproduced with a spin Hamiltonian including a dominant Kitaev nearest-neighbor interaction, weaker Heisenberg interactions up to the third neighbor, and bond-dependent off-diagonal exchange interactions. Beyond the Kitaev interaction that alone would induce a quantum spin liquid state, the presence of these additional couplings is responsible for the zigzag-type long-range magnetic ordering observed at low temperature in both compounds. These results provide evidence for the realization of Kitaev-type coupling in cobalt-based materials, despite hosting a…

Random quantum circuits have emerged as useful toy models for entanglement transitions in quantum many-body systems. Here, the authors study a projective version of the transverse-field Ising model without unitary dynamics where the competition between two noncommuting measurements drives an entanglement transition. The authors identify a nonlocal classical process that captures the entanglement dynamics and relate the model to bond percolation in space-time. This leads to a conformal field theory description of the system at criticality which they verify numerically for large systems.

We present a framework to systematically address topological phases when finer partitionings of bands are taken into account, rather than only considering the two subspaces spanned by valence and conduction bands. Focusing on ${C}_{2}\mathcal{T}$-symmetric systems that have gained recent attention, for example, in the context of layered van-der-Waals graphene heterostructures, we relate these insights to homotopy groups of Grassmannians and flag varieties, which in turn correspond to cohomology classes and Wilson-flow approaches. We furthermore make use of a geometric construction, the so-called Pl\"ucker embedding, to induce windings in the band structure necessary to facilitate nontrivial topology. Specifically, this directly relates to the parametrization of the Grassmannian, which describes partitioning of an arbitrary band structure and is embedded in a better manageable exterior product space. From a physical perspective, our construction encapsulates and elucidates the concepts of fragile topological phases beyond symmetry indicators as well as non-Abelian reciprocal braiding…

We use the density matrix renormalization group (DMRG) to study the correlated electron states favored by the Coulomb interaction projected onto the narrow bands of twisted bilayer graphene within a spinless one-valley model. The Hilbert space of the narrow bands is constructed from a pair of hybrid Wannier states with opposite Chern numbers, maximally localized in one direction and Bloch extended in another direction. Depending on the parameters in the Bistritzer-Macdonald model, the DMRG in this basis determines the ground state at one particle per unit cell to be either the quantum anomalous Hall (QAH) state or a state with zero Hall conductivity which is nearly a product state. Based on this form, we then apply the variational method to study their competition, thus identifying three states: the QAH, a gapless ${C}_{2}\mathcal{T}$-symmetric nematic, and a gapped ${C}_{2}\mathcal{T}$-symmetric stripe. In the chiral limit, the energies of the two ${C}_{2}\mathcal{T}$-symmetric states are found to be significantly above the energy of the QAH. However, all three states are nearly…

A severe limitation of current acoustic metasurfaces remains in their modest tunability to meet multifrequency requirements and alterable functionalities on demand. Here, a reconfigurable curved acoustic metasurface for acoustic cloaking and illusion is reported. The structure is composed of an array of tunable helical units to break this limitation and realize continuously versatile sound manipulations. We theoretically, numerically and experimentally investigate the channel length represented by the helical depth, which is used to achieve full 2\ensuremath{\pi} phase shift continuously over the frequency range from 2 to 7 kHz. As pragmatic examples, we present by full-wave numerical simulations the concept of a curved metasurface for the continuously tunable acoustic multifunction, including broadband carpet cloaking and ground illusion at a wide working band. Then, we experimentally demonstrate these functionalities by showing an excellent effect to restore the disturbed reflective field from a cloaked object or to mimic an arbitrary shaped ground.

Topological physics has introduced a modern design principle in optics, providing build-in protection to specific types of disorder. This work demonstrates how such principles could be used to create a topological resonator in nanophotonic crystals so as to enable chiral light-matter interaction in the context of cavity quantum electrodynamics. A moderate Purcell effect is shown as an experimental proof of principle.

Interlayer excitons present in van der Waals heterostructures of transition metal dichalcogenides exhibit remarkably distinct effective $g$ factors compared to their monolayer counterparts. Here, the authors employ first-principles calculations to investigate the interlayer exciton $g$ factors in MoSe${}_{2}$/WSe${}_{2}$ vdW heterostructures revealing that they are strongly spin and stacking dependent. Furthermore, within the present approach it is possible to unambiguously identify the nature of various previously measured interlayer exciton peaks. This first-principles approach can potentially be applied to calculate exciton $g$ factors of any semiconductor.

The recent discovery of single-ion magnets with magnetic hysteresis above liquid-nitrogen temperatures placed these compounds among the best candidates to realize high-density storage devices. Starting from a prototypical dysprosocenium molecule, showing hysteresis up to 60 K, we derive here a general recipe to design high-blocking-temperature rare-earth single-ion magnets. The complex magnetic relaxation is unraveled by combining magnetization and nuclear magnetic resonance measurements with inelastic neutron scattering experiments and ab initio calculations, thus disentangling the different mechanisms and identifying the key ingredients behind slow relaxation.

We propose an improved scheme to do the time-dependent variational principle (TDVP) in finite matrix product states (MPSs) for two-dimensional systems or one-dimensional systems with long-range interactions. We present a method to represent the time-evolving state in a MPS with its basis enriched by state averaging with global Krylov vectors. We show that the projection error is significantly reduced so precise time evolution can still be obtained even if a larger time step is used. Combined with the one-site TDVP, our approach provides a way to dynamically increase the bond dimension while still preserving unitarity for real-time evolution. Our method can be more accurate and exhibit slower bond dimension growth than the conventional two-site TDVP.

We analyze the phase diagram of twisted graphene bilayers near a magic angle. We consider the effect of the long-range Coulomb interaction, treated within the self-consistent Hartree-Fock approximation, and we study arbitrary band fillings. We find a rich phase diagram, with different broken symmetry phases, although they do not show necessarily a gap at the Fermi energy. There are nontrivial effects of the electrostatic potential on the shape and the gaps of the bands in the broken symmetry phases. The results suggest that the nonsuperconducting broken symmetry phases observed experimentally are induced by the long-range exchange interaction.

Magnon-photon coupling inside a cavity has been experimentally realized and has attracted significant attention for its potential docking with quantum information science. Whether this coupling implies the steady entanglement of photons and magnons is crucial for its usage in quantum information but is still an open question. Here we study the entanglement properties among magnons and photons in an antiferromagnet-light system and find that the entanglement between a magnon and a photon is nearly zero, while the magnon-magnon entanglement is very strong and can be even further enhanced through the coupling with the cavity photons. The maximum enhancement occurs when the antiferromagnet is resonant with the light. The essential physics can be well understood within the picture of cavity-induced cooling of the magnon-magnon state near its joint vacuum with stronger entanglement. Our findings can be used to cool magnetic magnons toward their ground state and may also be significant to extend the cavity spintronics to quantum manipulation. Furthermore, the hybrid antiferromagnet-light…

The $\ensuremath{\eta}$-pairing states are a set of exactly known eigenstates of the Hubbard model on hypercubic lattices, first discovered by Yang [C. N. Yang, Phys. Rev. Lett. 63, 2144 (1989)]. These states are not many-body scar states in the Hubbard model because they occupy unique symmetry sectors defined by the so-called $\ensuremath{\eta}$-pairing SU(2) symmetry. We study an extended Hubbard model with bond-charge interactions, popularized by Hirsch [J. E. Hirsch, Physica C 158, 326 (1989)], where the $\ensuremath{\eta}$-pairing states survive without the $\ensuremath{\eta}$-pairing symmetry and become true scar states. We also discuss similarities between the $\ensuremath{\eta}$-pairing states and exact scar towers in the spin-1 XY model found by Schecter and Iadecola [M. Schecter and T. Iadecola, Phys. Rev. Lett. 123, 147201 (2019)], and systematically arrive at all nearest-neighbor terms that preserve such scar towers in one dimension. We also generalize these terms to arbitrary bipartite lattices. Our study of the spin-1 XY model also leads us to several scarred models,…

We study theoretically the localization properties of two distinct one-dimensional quasiperiodic lattice models with a single-particle mobility edge (SPME) separating extended and localized states in the energy spectrum. The first one is the familiar Soukoulis-Economou trichromatic potential model with two incommensurate potentials, and the second is a system consisting of two coupled 1D Aubry-Andr\'e chains each containing one incommensurate potential. We show that as a function of the Hamiltonian model parameters, both models have a wide single-particle intermediate phase, defined as the regime where localized and extended single-particle states coexist in the spectrum, leading to a behavior intermediate between purely extended or purely localized when the system is dynamically quenched from a generic initial state. Our results thus suggest that both systems could serve as interesting experimental platforms for studying the interplay between localized and extended states, and may provide insight into the role of the coupling of small baths to localized systems. We also calculate…

We investigate the localization-delocalization transition in one-dimensional non-Hermitian quasiperiodic lattices with exponential short-range hopping, which possess parity-time ($\mathcal{PT}$) symmetry. The localization transition induced by the non-Hermitian quasiperiodic potential is found to occur at the $\mathcal{PT}$-symmetry-breaking point. Our results also demonstrate the existence of energy-dependent mobility edges, which separate the extended states from localized states and are only associated with the real part of eigenenergies. The level statistics and Loschmidt echo dynamics are also studied.

The ability to manipulate the absorption bandwidth has enabled a wide range of applications, from narrowband lasing emission to broadband photodetection. Applying the concept to emerging two-dimensional materials has the potential to enable breakthroughs in advanced compact photonic and optoelectronic devices. Here we present a general method for tailoring the absorption bandwidth of graphene via critical coupling in the near-infrared regime. In a simple two-port resonant structure, dissipative graphene is integrated with a lossless photonic crystal slab, achieving a significant bandwidth manipulation up to 100 times from ultra-narrowband (0.50 nm) to broadband (>50 nm) with a maximum absorption efficiency of 0.5. The modulation mechanism lies in the intrinsic dependence of bandwidth on the relationship between radiation rate and dissipative loss rate, which is fulfilled by changing the structure parameters and graphene conductivity. This work offers an effective route to engineer light-graphene interactions and shows great prospects in designing high-performance graphene-based…

Atomic $4f$ states have been found to be essential players in the physical behavior of lanthanide compounds, at the Fermi level ${E}_{F}$ as in the proposed topological Kondo insulator ${\mathrm{SmB}}_{6}$, or further away as in the magnetic superconductor system $R{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ ($R$ = rare-earth ion) and in ${\mathrm{Y}}_{1\ensuremath{-}x}{\mathrm{Pr}}_{x}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$, where the $4f$ shell of Pr has a devastating effect on superconductivity. In hole-doped $R{\mathrm{NiO}}_{2}$, the $R$ = Nd member is found to be superconducting while $R$ = La is not, in spite of the calculated electronic structures being nearly identical. We report first-principles results that indicate that the Nd $4f$ moment affects states at ${E}_{F}$ in infinite-layer ${\mathrm{NdNiO}}_{2}$, an effect that will not occur for ${\mathrm{LaNiO}}_{2}$. Treating 20% hole doping in the virtual crystal approach indicates that 0.15 holes empty the $\mathrm{\ensuremath{\Gamma}}$-centered Nd-derived electron pocket while leaving the other electron…

The rapidly developing collaboration of condensed matter and quantum optical physics opens up exciting new possibilities for creating novel photon-matter states that allow manipulating material properties using optical cavities. This paper addresses the important challenge of formulating consistent, accurate, and convenient forms of the light-matter coupling for the low-energy tight-binding-type models useful for theoretical analysis. It achieves this by constructing precise mappings from the fundamental $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ description of the cavity-matter system to low-energy theories, producing a truncated Hamiltonian coupling to a quantum Peierls phase. In a simple model system, the authors demonstrate the quick convergence of the truncated Hamiltonian with the number of bands, paving the way for rigorous theoretical studies in this emerging research field.

Monolayer semiconductors with suppressed environmental disorder from encapsulation in high-quality insulators provide a versatile platform to study the propagation of excitonic quasiparticles at ambient conditions. Using time-resolved emission microscopy, the authors monitored linear and nonlinear exciton diffusion in single layers of tungsten disulfide, observing highly mobile excitons with nonmonotonic density dependence of the diffusion. Combining experiment and theory, the authors discuss the impact of multivalley band structure, the role of bound and free charge carriers, the interplay of nonradiative recombination and diffusion as well as the suppressed Auger recombination.

We have investigated the sample dependence of the half-integer thermal Hall effect in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ under a magnetic field tilted ${45}^{\ensuremath{\circ}}$ from the $c$ axis to the $a$ axis. We find that the sample with the largest longitudinal thermal conductivity ${\ensuremath{\kappa}}_{xx}$ shows the half-integer quantized thermal Hall effect expected in the Kitaev model. On the other hand, the quantized thermal Hall effect was not observed in the samples with smaller ${\ensuremath{\kappa}}_{xx}$. We suggest that suppressing the magnetic scattering effects on the phonon thermal conduction, which broaden the field-induced gap protecting the chiral edge current of the Majorana fermions, is important to observe the quantized thermal Hall effect.

We theoretically propose a mechanism for the anomalous Hall effect (AHE) in an antiferromagnetic (AFM) state of $\ensuremath{\kappa}$-type organic conductors. We incorporate the spin-orbit coupling in the effective Hubbard model on the $\ensuremath{\kappa}$-type lattice structure, taking into account the orientation of the molecules and their arrangement with dimerization. Treating this model by means of the Hartree-Fock approximation and the linear response theory, we find that an intrinsic contribution to the Hall conductivity becomes nonzero in the electron-doped AFM metallic phase with a small canted ferromagnetic moment. We show that, contrary to the conventional wisdom, the spin canting is irrelevant to the Hall response; the nonzero Hall conductivity originates from the collinear component of the AFM order in the presence of the spin-orbit coupling. These features are well explained analytically in the limit of strong dimerization on the anisotropic triangular lattice. Furthermore, we present an intuitive picture for the present AHE by considering the real-space configuration…

Using SrNiO${}_{2}$ as a reference system, the authors find multiorbital Hund's metal behavior in the new Ni-based superconductor Nd${}_{1\ensuremath{-}x}$ SrxNiO${}_{2}$ by many-body $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ calculations. They show that both the weights of Ni 3$d$ multiplets and total Ni 3$d$ occupancy are barely changed from the typical Hund's metal SrNiO${}_{2}$ to LaNiO${}_{2}$ in spite of the large charge-carrier doping. The calculations are well justified by existing experiments with important implications on the pairing mechanism.

Twisted bilayer graphene displays insulating and superconducting phases caused by flattening of its energy band. In the superconducting dome near hole half-filling, the threefold lattice rotation symmetry is broken, and the superconductor is also a nematic. The authors argue that superconductivity can be properly described by a patch model near twelve Van Hove points and show that there is nearly equal attractive interaction in two different superconducting channels. They go on to explicitly demonstrate that when both orders develop, the superconducting state is also a nematic.

We analyze local operator growth in nonintegrable quantum many-body systems. A recently introduced universal operator growth hypothesis proposes that the maximal growth of Lanczos coefficients in the continued fraction expansion of the Green's function reflects chaos of the underlying system. We first show that the continued fraction expansion, and the recursion method in general, should be understood in the context of a completely integrable classical dynamics in Krylov space. In particular, the time-correlation function of a physical observable analytically continued to imaginary time is a tau-function of integrable Toda hierarchy. We use this relation to generalize the universal operator growth hypothesis to include arbitrarily ordered correlation functions. We then proceed to analyze the singularity of the time-correlation function, which is an equivalent sign of chaos to the maximal growth of Lanczos coefficients, and we show that it is due to delocalization in Krylov space. We illustrate the general relation between chaos and delocalization using an explicit example of the…

We study a stochastic lattice gas of particles in one dimension with strictly finite-range interactions that respect the fractonlike conservation laws of total charge and dipole moment. As the charge density is varied, the connectivity of the system's charge configurations under the dynamics changes qualitatively. We find two distinct phases: Near half filling the system thermalizes subdiffusively, with almost all configurations belonging to a single dynamically connected sector. As the charge density is tuned away from half filling there is a phase transition to a frozen phase, where locally active finite bubbles cannot exchange particles and the system fails to thermalize. The two phases exemplify what has recently been referred to as weak and strong Hilbert space fragmentation, respectively. We study the static and dynamic scaling properties of this weak-to-strong fragmentation phase transition in a kinetically constrained classical Markov circuit model, obtaining some conjectured exact critical exponents.

We propose a realization of an antisymmetric spin-split band structure through magnetic phase transitions without spin-orbit coupling. It enables us to utilize it for a variety of magnetic-order-driven cross-correlated and nonreciprocal transport phenomena as similar to those in spin-orbit-coupling oriented systems. We unveil its general condition as an emergence of a bond-type magnetic toroidal multipole (polar tensor) in a triangular unit with noncollinear ${120}^{\ensuremath{\circ}}$ antiferromagnetic structures. By using the concept of augmented multipoles, we systematically analyze the phenomena in terms of an effective multipole coupling. Our multipole description is ubiquitously applied to any trigonal and hexagonal structures including triangular, kagome, and breathing kagome structures, and provides a way to design and engineer materials with a giant antisymmetric spin splitting and its physical responses even without spin-orbit coupling.

$\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnAl}$ has been predicted to have Weyl points near the Fermi level in $L{2}_{1}$-ordered structure, which is expected to give rise to exotic transverse transport properties such as large anomalous Hall (AHE) and Nernst effects (ANE) due to large Berry curvature. In this study, the effects of Fermi level position and atomic ordering on AHE and ANE in $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnA}{\mathrm{l}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{i}}_{x}$ were studied systematically. The $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnAl}$ film keeps $B2$-disordred structure regardless of annealing temperature, which results in much smaller anomalous Hall conductivity ${\ensuremath{\sigma}}_{xy}$ and transverse Peltier coefficient ${\ensuremath{\alpha}}_{xy}$ than those calculated for $L{2}_{1}$-ordered $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnAl}$. Our newly performed calculation of ${\ensuremath{\sigma}}_{xy}$ with taking $B2$ disordering into account well reproduces the experimental result; thus it was concluded that Berry curvature originating from the Weyl points is…

We theoretically study a generalized Hubbard model on Moir\'e superlattices of twisted bilayers, and find very rich filling-factor-dependent quantum phase diagrams tuned by interaction strength and twist angle. Strong long-range Coulomb interaction in the Moir\'e-Hubbard model induces Wigner crystals at a series of fractional filling factors. The effective lattice of the Wigner crystal is controlled by the filling factor, and can be triangle, rectangle, honeycomb, kagome, etc., providing a single platform to realize many different spin models on various lattices by simply tuning carrier density. In addition to Wigner crystals that are topologically trivial, interaction-induced Chern insulators emerge in the phase diagram. This finding paves a way for engineering interaction-induced quantum anomalous Hall effect in Moir\'e-Hubbard systems where the corresponding single-particle Moir\'e band is topologically trivial.

This work demonstrates that Kirchhoff's law of radiation, stating that the spectral directional emissivity and absorptivity of a surface are equal at thermal equilibrium, can be violated in planar surfaces without an external magnetic field or structures such as gratings. Modeling a type-I magnetic Weyl semimetal with an antisymmetric dielectric tensor, we show an intrinsic violation of Kirchhoff's law due to nonreciprocal surface polaritons induced by the Berry curvature and anomalous Hall velocity. This work provides a simple way to physically realize the violation of Kirchhoff's law.

Non-Hermitian quantum many-body systems are a fascinating subject to be explored. Using the generalized density matrix renormalization group method and complementary exact diagonalization, we elucidate the many-body ground states and dynamics of a 1D interacting non-Hermitian Aubry-Andr\'e-Harper model for bosons. We find stable ground states in the superfluid and Mott-insulating regimes under wide range of conditions in this model. We reveal a skin superfluid state induced by the non-Hermiticity from the nonreciprocal hopping. We investigate the topology of the Mott-insulating phase and find its independence of the non-Hermiticity. The topological Mott insulators in this non-Hermitian system are characterized by four equal Chern numbers and a quantized shift of biorthogonal many-body polarizations. Furthermore, we show generic asymmetric expansion and correlation dynamics in the system.

We describe the crossover from generalized to conventional hydrodynamics in nearly integrable systems. Integrable systems have infinitely many conserved quantities, which spread ballistically, in general. When integrability is broken, only a few of these conserved quantities survive. The remaining conserved quantities are generically transported diffusively; we derive a compact and general diffusion equation for these. The diffusion constant depends on the matrix elements of the integrability-breaking perturbation; for a certain class of integrability-breaking perturbations, including long-range interactions, the diffusion constant can be expressed entirely in terms of generalized hydrodynamic data.

Despite considerable interest, it has been difficult to conclusively determine the ground state of twisted bilayer graphene (tBLG), due to the long-range nature of the Coulomb interaction and the fragile topology of the tBLG flat bands. This paper puts forward a method for studying tBLG more efficiently: mixed-$x\phantom{\rule{0}{0ex}}k$ space density-matrix renormalization group (DMRG) with matrix product operator (MPO) compression. The method enables the authors to calculate accurately the ground state of single-valley single-spin tBLG, and it puts DMRG with more degrees of freedom, such as valley, within reach.

The non-Hermiticity caused breakdown of the bulk-boundary correspondence (BBC) in topological phase transition was cured by the skin effect for the systems with chiral symmetry and translation invariance. However, periodic driving, as an active tool in engineering exotic topological phases, breaks the chiral symmetry, and the inevitable disorder destroys the translation invariance. Here, we propose a scheme to retrieve the BBC and establish a complete description of the topological phases of the periodically driven non-Hermitian system both with and without the translation invariance. The demonstration of our method in the non-Hermitian Su-Schrieffer-Heeger model shows that exotic non-Hermitian topological phases of widely tunable numbers of edge states and Floquet topological Anderson insulator are induced by the periodic driving and the disorder. Our result supplies a useful way to artificially synthesize exotic phases by periodic driving in the non-Hermitian system.

In this paper, we study the properties of two-dimensional lattices in the presence of non-Hermitian disorder. In the context of coupled mode theory, we consider random gain-loss distributions on every waveguide channel (on site disorder). Our work provides a systematic study of the interplay between disorder and non-Hermiticity. In particular, we study the eigenspectrum in the complex frequency plane and we examine the localization properties of the eigenstates, either by the participation ratio or the level spacing, defined in the complex plane. A modified level distribution function vs disorder seems to fit our computational results.

Utilization of van der Waals magnetic materials as the host of topologically protected skyrmionic and other complex spin textures has been drawing increasing attention. Here, using first-principles-based calculations, we predict a new stable magnetic ${\mathrm{CrGe}(\mathrm{Se},\mathrm{Te})}_{3}$ Janus monolayer with a strong Dzyaloshinskii-Moriya interaction (DMI), due to the breaking of inversion symmetry. Consequently, nanometric skyrmions (that carry a topological charge of $\ifmmode\pm\else\textpm\fi{}1$) and skyrmionium states (with a zero topological charge) can spontaneously form in the absence of magnetic field. We further unveil a subtle competition between DMI and frustration as key for stabilizing skyrmioniums.

Magnetic frustration has been a source of inspiration to condensed matter physicists for many years, usually as a means to obtain exotic low-energy physics. Here, magnetic frustration is shown to lead to various classes of models with anomalous eigenstates embedded in the high-energy spectrum. These include states called many-body quantum scars that live in a sea of typical eigenstates. The work also shows that the entire spectrum can be scarred through a fragmentation of Hilbert space generated by frustration.

Periodically driven non-Hermitian systems can exhibit rich topological band structure and non-Hermitian skin effect, without analogs in their static or Hermitian counterparts. In this work we investigate the exceptional band-touching points in the Floquet quasienergy bands, the topological characterization of such exceptional points and the Floquet non-Hermitian skin effect (FNHSE). Specifically, we exploit the simplicity of periodically quenched two-band systems in one dimension or two dimensions to analytically obtain the Floquet effective Hamiltonian as well as locations of the many exceptional points possessed by the Floquet bulk bands. Two different types of topological winding numbers are used to characterize the topological features. Bulk-boundary correspondence (BBC) is naturally found to break down due to FNHSE, which can be drastically different among different bulk states. Remarkably, given the simple nature of our model systems, recovering the BBC is doable in practice only for certain parameter regime where a low-order truncation of the characteristic polynomial (which…

Local observables of closed many-body quantum systems are generally believed to quickly equilibrate after a quench, according to the eigenstate thermalization hypothesis. Here, the authors show that the paradigmatic Heisenberg quantum magnet violates this fundamental assumption. They analytically find measurable local correlation functions that show perpetual oscillations, while at the same time all single-particle observables equilibrate. They link their existence to the presence of dynamical symmetries and obtain a fractal dependence of their oscillation frequency on the interaction strength.

Recent experiments have established previously predicted ${\mathrm{LaH}}_{10}$ as the highest-temperature superconductor, with ${T}_{C}$ up to 250--260 K [Drozdov et al., Nature (London) 569, 528 (2019); Somayazulu et al., Phys. Rev. Lett. 122, 027001 (2019)]. In this work we explore the high-pressure phase stability and superconductivity of lanthanum hydrides ${\mathrm{LaH}}_{m}$. We predict the stability of the hitherto unreported polyhydride $P6/mmm\ensuremath{-}{\mathrm{LaH}}_{16}$ at pressures above 150 GPa; at 200 GPa, its predicted superconducting ${T}_{C}$ is 156 K, the critical field ${\ensuremath{\mu}}_{0}{H}_{C}(0)$ is approximately 35 T, and the superconducting gap is up to 35 meV. We revisit the superconductivity of ${\mathrm{LaH}}_{10}$ and find its ${T}_{C}$ to be up to 259 K at 170 GPa from solving the Eliashberg equation and 271 K from solving the gap equation within the superconducting density functional theory, which also allows us to compute the Coulomb pseudopotential ${\ensuremath{\mu}}^{*}$ for ${\mathrm{LaH}}_{10}$ and ${\mathrm{LaH}}_{16}$.

Quantum interference on the kagome lattice generates electronic bands with narrow bandwidth, called flat bands. Crystal structures incorporating this lattice can host strong electron correlations with nonstandard ingredients, but only if these bands lie at the Fermi level. In the six compounds with the CoSn structure type (FeGe, FeSn, CoSn, NiIn, RhPb, and PtTl) the transition metals form a kagome lattice. The two iron variants are robust antiferromagnets so we focus on the latter four and investigate their thermodynamic and transport properties. We consider these results and calculated band structures to locate and characterize the flat bands in these materials. We propose that CoSn and RhPb deserve the community's attention for exploring flat-band physics.

In elastic systems, the current technique to produce Dirac degeneracy is based on Bragg scattering eigenstates, which, however, suffers from operating only at relatively high frequency determined by lattice constant. Here, an elastic metamaterial plate that presents an analog to the quantum valley Hall effect (QVHE) is proposed to achieve Dirac degeneracy with local resonant states, enabling us to tune the operating frequency without altering the lattice. By introducing resonator pair into a hexagonal lattice, a local resonance states-induced Dirac cone is produced right below the local resonant band gap caused by the resonator pair. After gapping the Dirac cone with unequal masses of the resonator pair, a new local resonant band gap supporting topological edge modes immune to backscattering appears. This band gap is formed by mixing effective negative mass effect and Bragg scattering effect due to large virtual mass. These ideas are demonstrated by numerical simulation, as well as validated by the experiment on flexural wave in a textured plate. The proposed design provides a new…

We study the scrambling of quantum information in local random unitary circuits by focusing on the tripartite information proposed by Hosur et al. We provide exact results for the averaged R\'enyi-2 tripartite information in two cases: (i) the local gates are Haar random and (ii) the local gates are dual-unitary and randomly sampled from a single-site Haar-invariant measure. We show that the latter case defines a one-parameter family of circuits, and prove that for a ``maximally chaotic'' subset of this family quantum information is scrambled faster than in the Haar-random case. Our approach is based on a standard mapping onto an averaged folded tensor network, that can be studied by means of appropriate recurrence relations. By means of the same method, we also revisit the computation of out-of-time-ordered correlation functions, rederiving known formulas for Haar-random unitary circuits, and presenting an exact result for maximally chaotic random dual-unitary gates.

We report on the efficient spin-orbit torque (SOT) switching in a single ferromagnetic layer induced by a new type of inversion asymmetry, the composition gradient. The SOT of 6- to 60-nm epitaxial FePt thin films with a $L{1}_{0}$ phase is investigated. The magnetization of the FePt single layer can be reversibly switched by applying electrical current with a moderate current density. Different from previously reported SOTs which either decreases with or does not change with the film thickness, the SOT in FePt increases with the film thickness. We found the SOT in FePt can be attributed to the composition gradient along the film normal direction. A linear correlation between the SOT and the composition gradient is observed. This Rapid Communication introduces a platform to engineer large SOTs for lower-power spintronics.

In hexagonal two-dimensional (2D) materials such as graphene, hexagonal boron nitride, or transition metal dichalcogenides, electrons possess intrinsic degrees of freedom (DOFs): sublattice pseudospin, spin, and valley. Independent polarization of the DOFs for carrying information can be harnessed in future semiconductor industry. Here we propose a general Hamiltonian based on the Haldane model with spin-orbit coupling (SOC) which realizes the independence of all the DOFs that can tune optical absorption spectra as a function of the SOC. The present result suggests a new 2D material or a new 2D electronic device which offers any combination of pseudospintronics, spintronics, and valleytronics applications.