Abstract In this review, the thermoelectric properties in nodal‐point semimetals with two bands are discussed. For two‐dimensional (2D) cases, it is shown that expressions of coefficients take different values depending on nature scattering mechanism responsible for transport, by considering examples short‐ranged disorder potential and screened charged impurities. An anisotropy energy dispersion spectrum invariably affects thermopower quite significantly, as illustrated results a node...

We study topological charge pumping (TCP) in the Rice-Mele (RM) model with irreciprocal hopping. The non-Hermiticity gives rise to interesting physics, owing presence of skin effect and exceptional points. In static one-dimensional (1D) RM model, we find two independent tuning knobs that can drive transition, namely, non-Hermitian parameter $\gamma$ system size $N$. To elucidate system-size dependency, use a finite-size generalized Brillouin zone (GBZ) scheme show edge modes be distinguished...

Two-dimensional (2D) semi-Dirac materials are characterized by a quadratic dispersion in one direction and linear along the orthogonal direction. We study topological phase transition such 2D systems presence of an electromagnetic field. show that Chern insulating state emerges system with two gapless Dirac nodes light. In particular, we intensity circularly polarized light can be used as knob to generate states nonzero number. addition, for fixed frequency light, gapped trivial band...

We report the presence of multiple flat bands in a class two-dimensional (2D) lattices formed by Sierpinski gasket (SPG) fractal geometries as basic unit cells. Solving tight-binding Hamiltonian for such with different generations SPG network, we find degenerate and non-degenerate completely bands, depending on configuration parameters Hamiltonian. Moreover, generic formula to determine number function generation index $\ell$ geometry. show that their neighboring dispersive have remarkable...

We develop an approximate theory of phonon-induced topological insulation in Dirac materials. In the weak-coupling regime, long-wavelength phonons may favor phases insulators with direct and narrow band gaps. This phenomenon originates from electron-phonon matrix elements, which change qualitatively under a inversion. A similar mechanism applies to weak Coulomb interactions spin-independent disorder; however, influence these on topology is largely independent temperature. As applications...

We investigate the generation of an electric current from a temperature gradient in two-dimensional Weyl semimetal with anisotropy both presence and absence quantizing magnetic field. show that leads to doping dependences thermopower thermal conductivities which are different those isotropic Dirac materials. Additionally, we find field such systems interesting dependence longitudinal thermopower, resulting unsaturated thermoelectric coefficients. Thus, results presented here will serve as...

We study the Mott phases and superfluid-insulator transition of two-component ultracold bosons on a square optical lattice in presence non-Abelian synthetic gauge field, which renders SU(2) hopping matrix for bosons. Using resummed expansion, we calculate excitation spectra insulating demonstrate that phase boundary displays non-monotonic dependence field strength. also compute momentum distribution show they develop peaks at non-zero momenta as point is approached from side. Finally,...

We describe a quasiperiodic optical lattice, created by physical realization of the abstract cut-and-project construction underlying all quasicrystals. The resulting potential is generalization Fibonacci tiling. Calculation energies and wave functions ultracold atoms loaded into such lattice demonstrate multifractal energy spectrum, singular continuous momentum-space structure, existence controllable edge states. These results open door to cold atom quantum simulation experiments in tunable...

Abstract We study topological charge pumping (TCP) in the Rice-Mele (RM) model with irreciprocal hopping. The non-Hermiticity gives rise to interesting physics, owing presence of skin effect and exceptional points. In static one-dimensional (1D) RM model, we find two independent tuning knobs that can drive transition, namely, non-Hermitian parameter $\gamma$ system size $N$. To elucidate system-size dependency, use a finite-size generalized Brillouin zone (GBZ) scheme show edge modes be...

Abstract Non-magnetic materials without inversion symmetry typically exhibit strong Rashba spin-orbit coupling (SOC), enabling the well-known Edelstein effect where an external electrical current induces transverse spin polarisation. In this study, we demonstrate that electrically induced polarisation in non-magnetic materials, for example, electronic systems within quantum-well geometries, can significantly be influenced by system’s point-group symmetries, such as C n and nv . These...

We theoretically investigate the heterostructure between a ferrimagnetic Mott insulator and time-reversal invariant topological band on two-dimensional Lieb lattice with periodic boundary conditions. Our Hartree-Fock slave-rotor mean-field results incorporate long-range Coulomb interactions. present charge magnetic reconstructions at two edges of reveal how \textit{buried} edge modes adapt to these reconstructions. In particular, we demonstrate that interface field induces spin imbalance in...

We compute the tunneling conductance of graphene as measured by a scanning microscope (STM) with normal/superconducting tip. demonstrate that for undoped zero Fermi energy, first derivative respect to applied voltage is proportional density states STM also show shape spectra doped impurities depends qualitatively on position impurity atom in matrix and relate this unconventional phenomenon pseudospin symmetry Dirac quasiparticles graphene. suggest experiments test our theory.

We present a quantitative microscopic theory of the disorder- and phonon-induced coupling between surface bulk states in topological insulator (TI) films. find simple structure for surface-to-bulk scattering matrix elements confirm importance bulk-surface transport photoemission experiments, assessing its dependence on temperature, carrier density, film thickness particle-hole asymmetry.

Motivated by recent experiments [Y. J. Lin et al., Nature (London) 471, 83 (2011)], we study Mott phases and superfluid-insulator (SI) transitions of two-species ultracold bosonic atoms in a two-dimensional square optical lattice with nearest-neighbor hopping amplitude $t$ the presence spin-orbit coupling characterized tunable strength $\ensuremath{\gamma}$. Using both strong-coupling expansion Gutzwiller mean-field theory, chart out phase diagrams bosons such interaction. We compute...

The interplay between topological phases of matter and dissipative baths constitutes an emergent research topic with links to condensed matter, photonic crystals, cold atomic gases, quantum information. While recent studies suggest that can induce in intrinsically trivial materials, the backaction invariants on is overlooked. By exploring this for a centrosymmetric Dirac insulator coupled phonons, we show linewidths bulk optical phonons reveal electronic band inversions. This result first...

We investigate the role of disorder in a two-dimensional semi-Dirac material characterized by linear dispersion one direction and parabolic orthogonal direction. Using self-consistent Born approximation, we show that can drive topological Lifshitz transition from an insulator to semimetal, as it generates momentum-independent off-diagonal contribution self-energy. Breaking time-reversal symmetry enriches phase diagram with three distinct regimes---single-node trivial, two-node Chern. find...

It has recently been realized that the first-order moment of Berry curvature, namely, curvature dipole (BCD), can give rise to nonlinear current in a wide variety time-reversal invariant and non-centrosymmetric materials. While BCD two-dimensional Dirac systems is known be finite only presence either substantial spin-orbit coupling where low-energy quasiparticles form tilted cones or higher order warping Fermi surface, we argue arising from merging pair points without any tilt surface lead...

We study the stroboscopic dynamics of hinge modes a second-order topological material modeled by tight-binding free fermion Hamiltonian on cubic lattice in intermediate drive frequency regime for both discrete (square pulse) and continuous (cosine) periodic protocols. analyze Floquet phases this system show that its quasienergy spectrum becomes almost gapless large amplitude at special frequencies. Away from these frequencies, gapped supports weakly dispersing modes. Near them, penetrate...

We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate (BEC) which is confined between two parallel plates. considered Dirichlet boundary conditions wave function as well phonon field. shown that, (which obeys Gross-Pitaevskii equation) responsible mean field part of force, usually dominates over quantum (fluctuations) force.

At large values of the anisotropy Δ, open-boundary Heisenberg spin- chain has eigenstates displaying localization at edges. We present a Bethe ansatz description this 'edge-locking' phenomenon in entire Δ > 1 region. focus on simplest spin sectors, namely highly polarized sectors with only one or two overturned spins, i.e., one-particle and two-particle sectors.

We investigate parity-odd nondissipative transport in an anisotropic Dirac semimetal two spatial dimensions. The analysis is relevant for interacting electronic systems with merging points at charge neutrality. For such the dispersion relation relativistic one direction and nonrelativistic other. give a proposal of how to calculate Berry curvature this system use it derive more than odd viscosities, contrast rotationally invariant systems. observe that model part viscosity tensor...

We chart out the possible phases of laser driven Rydberg atoms in presence a hypercubic optical lattice. define pseudospin degree freedom whose up(down) components correspond to excited(ground) states and use them demonstrate realization canted Ising antiferromagnetic (CIAF) Mott phase these systems. also show that on lowering lattice depth, quantum melting CIAF density-wave (DW) (which are realized systems) leads supersolid (SS) atoms. provide analytical expressions for boundaries...

We provide a theory for the tunneling conductance $G(V)$ of Dirac Fermions on surface topological insulator as measured by spin-polarized scanning microscope tip low bias voltages $V$. show that exhibits an unconventional dependence direction magnetization and can be used to measure magnitude local out-of-plane spin orientation surface. also demonstrate if in-plane rotational symmetry is broken external field, then acquires azimuthal angle tip. explain role in this behavior suggest...

We theoretically study the non-linear response of interacting neutral bosonic gas in a synthetically driven one-dimensional optical lattice. In particular, we examine analogue electronic higher harmonic generation strong time-dependent synthetic vector potential manifesting itself as electric field. show that can generate reasonably high harmonics insulating regime, while superfluid regime exhibits only few harmonics. number increases with increase strength potential. This originates...