We study theoretically the electronic states in a 5d transition metal oxide Na2IrO3, which both spin-orbit interaction and electron correlation play crucial roles. A tight-binding model analysis together with first-principles band structure calculation predicts that this material is layered quantum spin Hall system. Because of correlation, an antiferromagnetic order first develops at edge, later inside bulk low temperatures.

We study the polarization response to a temperature gradient in insulators, known as thermopolarization effect. show that this can be understood through free energy function an electric field gradient, which we call Q tensor. By using tensor, present unified description of responses both fields and gradients derive generalized Mott relation. Additionally, draw analogy with anomalous Hall Nernst effects. These effects are observable Seebeck effect when system's linear size is shorter than...

The spin Hall (SH) effect is widely understood as a phenomoenon in which current flows perpendicular to an electric field. In the presence of spin-orbit coupling, however, ambiguous, and SH conductivity depends on definition current. this article, we develop \textit{ab initio} computational scheme for accumulation coefficient, characterizes would be alternative indicator effect. proposed method has been implemented into open-source software Wannier90 serves high-precision research

We revisit a theory of heat transport in the light gauge gravity and find proper current with corresponding field, which yields natural definitions magnetization Kubo-formula contribution to thermal conductivity as torsional responses. also develop general framework for calculating gravitational responses by combining Keldysh Cartan formalisms. By using this framework, we explicitly calculate these two quantities reproduce Wiedemann–Franz law Hall clean non-interacting case. Finally, discuss...

We derive a quantum-mechanical formula of the orbital magnetic quadrupole moment (MQM) in periodic systems by using gauge-covariant gradient expansion. This is valid for insulators and metals at zero nonzero temperature. also prove direct relation between MQM magnetoelectric (ME) susceptibility It indicates that microscopic origin ME effect. Using formula, we quantitatively estimate these quantities room-temperature antiferromagnetic semiconductors ${\mathrm{BaMn}}_{2}{\mathrm{As}}_{2}$...

We report a new type of spin-orbit coupling (SOC) called geometric SOC. Starting from the relativistic theory in curved space, we derive an effective nonrelativistic Hamiltonian generic curve embedded into flat three dimensions. The SOC is $O(m^{-1})$, which $m$ electron mass, and hence much larger than conventional $O(m^{-2})$. energy scale estimated to be hundred meV for nanoscale helix. calculate current-induced spin polarization coupled-helix model as representative chirality-induced...

We establish the Berry-phase formulas for angular momentum (AM) and Hall viscosity (HV) to investigate chiral superconductors (SCs) in two three dimensions. The AM is defined by temporal integral of antisymmetric current induced an adiabatic deformation, while HV symmetric torsional electric field. Without suffering from system size or geometry, we obtain macroscopic ${L}_{z}=\ensuremath{\hbar}m{N}_{0}/2$ at zero temperature full-gap SCs, where $m$ magnetic quantum number ${N}_{0}$ total...

We revisit a quantum-mechanical formula of the spin magnetic quadrupole moment (MQM) in periodic crystals. Two previous attempts were inconsistent with each other; one is gauge dependent, and other invariant. Here we define MQM by calculating density nonuniform system. Our definition analogous to that charge polarization, but result invariant coincides latter one. also formulate what call gravitomagnetoelectric (gravito-ME) effect, which magnetization induced temperature gradient. Although...

The spin Hall (SH) effect is a phenomenon in which the current flows perpendicular to an applied electric field and causes accumulation at boundaries. However, presence of spin-orbit couplings, not well defined. Here, we calculate response electric-field gradient, naturally appears We derive generic formula using Bloch wave functions phenomenological relaxation time. also for uniform Rashba model with $\delta$-function nonmagnetic disorder within first-order Born approximation corresponding...

The anomalous Hall effect in a multiband tight-binding model is numerically studied taking into account both elastic scattering by disorder and inelastic the electron-phonon interaction. conductivity obtained as function of temperature $T$, rate $γ$, chemical potential $μ$, impurity concentration $x_{\rm imp}$. We find that new scaling law holds over wide range these parameters; $-σ_{xy}= (ασ_{xx0}^{-1} + βσ_{xx0}^{-2}) σ_{xx}^2 b$, with $σ_{μν}$ ($σ_{μν0}$) being tensor (with only...

Higher-rank electric/magnetic multipole moments are attracting attention these days as candidate order parameters for exotic material phases. However, quantum-mechanical formulation of those is still an ongoing issue. In this paper, we propose a thermodynamic definition electric quadrupole measure symmetry breaking, following previous studies orbital magnetic dipole and moments. The obtained formulas illustrated with model orbital-ordered nematic phases iron-based superconductors.

We investigate the bulk orbital angular momentum in a two-dimensional time-reversal broken topological superconductor with Rashba spin-orbit interaction, Zeeman and $s$-wave pairing potential. Prior to phase transition, we find crossover from $s$ wave $p$ wave. For large even phase, ${L}_{z}/N$ does not reach $\ensuremath{-}1/2$, which is intrinsic value chiral $p$-wave superconductors. Here ${L}_{z}$ $N$ are total number of electrons at zero temperature, respectively. Finally, discuss...

We formulate the chiral vortical effect (CVE) and its generalization called generalized using semiclassical theory of wave packet dynamics. take spin-vorticity coupling into account calculate transport charge current by subtracting magnetization one from Noether local one. find that in CVE always vanishes relativistic fermions. This result implies it cannot be observed experiments condensed matter systems such as Dirac/Weyl semimetals with pseudo-Lorentz symmetry. also demonstrate...

We study the magnon contribution to gravitomagnetoelectric (gravito-ME) effect, in which magnetization is induced by a temperature gradient, noncentrosymmetric antiferromagnetic insulators. This phenomenon totally different from ME because gradient coupled magnons but an electric field not. derive general formula of gravito-ME susceptibility terms wave functions and find that difference $g$ factors magnetic ions crucial. also apply our specific model. Although obtained small, we discuss...

We investigate the electric and thermal transport properties in a disordered Weyl ferromagnet on an equal footing by using Keldysh formalism curved spacetime. In particular, we calculate anomalous Hall conductivity, which consists of Kubo formula heat magnetization, without relying Wiedemann–Franz law. take nonmagnetic impurities into account within self-consistent T-matrix approximation reproduce law for extrinsic Fermi-surface intrinsic Fermi-sea terms, respectively. This is first step...

Frequency shifts and nuclear relaxations of $^{13}\mathrm{C}$ NMR the metal-insulator alternating layered material $(\mathrm{Me}\text{\ensuremath{-}}3,5\text{\ensuremath{-}}\mathrm{DIP})[\mathrm{Ni}(\mathrm{dmit}{)}_{2}{]}_{2}$, are presented. The absorption lines originating from metallic insulating layers well resolved, which evidences coexistence localized spins $({\ensuremath{\pi}}_{\mathrm{loc}})$ conduction $\ensuremath{\pi}$ electrons. line is found to be wiped out at about...

We propose purely electric manipulation of spin qubits by means the spin-orbit interaction (SOI) without magnetic field or magnets in a double quantum dot. All unitary transformations can be constructed time-dependent Dzyaloshinsky-Moriya between two spins, which arises from Rashba SOI modulated field. As few demonstrations, we study both analytically and numerically three operations, i.e., (A) initialization, (B) two-spin rotation opposite directions, (C) same direction. The effects...

We investigate the heat polarization, a analog of charge by using gauge-covariant Keldysh formalism. In contrast to charge-heat analogy naively expected, we find that polarization does not appear spontaneously, since it consists only heat-transfer contribution but heat-generation contribution, leading Mott rule. Nonetheless, can be induced torsional magnetic field in $(3+1)$-D topological insulators and superconductors, which is described temporal part Nieh-Yan action.

We investigate the bulk orbital angular momentum (AM) in a two-dimensional hole-doped topological superconductor (SC) which is composed of semiconductor thin film, magnetic insulator, and an $s$-wave SC characterized by Chern number $C = -3$. In phase, $L_z/N$ strongly reduced from intrinsic value non-particle-hole-symmetric edge states as corresponding chiral $f$-wave SCs when spin-orbit interactions (SOIs) are small, while this reduction does not work for large SOIs. Here $L_z$ $N$ AM...

The axial magnetic effect (AME) is one of the anomalous transport phenomena in which energy current induced by an field. Here, we numerically study AME for relativistic Wilson fermion field and a twisted Dirac semimetal. density inside bulk nonzero, particularly low-energy regime former model, it explained field-theoretical results without any fitting parameter. However, both models, average vanishes owing to surface contribution. gauge regarded as spatially modulated (effective) Zeeman...

The spin Nernst effect is a phenomenon in which the current flows perpendicular to temperature gradient. Similar Hall effect, this also causes accumulation at boundaries. Here, we study response gradient of with use Green's functions. Our formalism predicts physically observable without ambiguity regarding definition or magnetization correction. We prove generalized Mott relation between electric and thermal responses assuming presence time-reversal symmetry absence inelastic scattering....