Theory of spin magnetic quadrupole moment and temperature-gradient-induced magnetization

We present a general quantum kinetic theory that accounts for the interplay between a temperature gradient, momentum-space Berry curvatures of Bloch electrons, and Bloch-state scattering. Using a theory that incorporates the presence of a temperature gradient by introducing a "thermal vector potential", we derive a quantum kinetic equation for Bloch electrons in the presence of disorder and a temperature gradient. In contrast to the semiclassical Boltzmann formalism in which a temperature gradient is introduced by settinġ r · ∂ ∂r →ṙ · ∂T ∂r ∂ ∂T in the Boltzmann equation, the presence of a temperature gradient in our formalism is described as a driving force just as in the case of an electric field (i.e., comes fromk in the language of the semiclassical Boltzmann formalism). Taking also into account the presence of electric and magnetic fields, the quantum kinetic equation we derive makes it possible to compute transport coefficients at arbitrary orders of electric-field E, magnetic-field B, and temperature-gradient ∇T strengths |E| a |B| b |∇T | c . Our theory enables a systematic calculation of magnetothermoelectric and magnetothermal conductivities of systems with momentum-space Berry curvatures. As an illustration, we derive from a general microscopic electron model a general expression for the rate of pumping of electrons between valleys in parallel temperature gradient and magnetic field. From this expression we find a relation, which is analogous to the Mott relation, between the rate of pumping due to a temperature gradient and that due to an electric field. We also apply our theory to a two-band model for Weyl semimetals to study thermoelectric and thermal transport in a magnetic field. We show that the Mott relation is satisfied in the chiral-anomaly induced thermoelectric conductivity, and that the Wiedemann-Franz law is violated in the chiral-anomaly induced thermal conductivity, which are both consistent with the results obtained by invoking semiclassical wave-packet dynamics. arXiv:1910.10642v1 [cond-mat.mes-hall]

Section: B Heat Current Induced By Electric Fieldmentioning

confidence: 99%

Quantum kinetic theory of thermoelectric and thermal transport in a magnetic field

Sekine

Nagaosa

2020

“…In this Rapid Communication, we study the gravito-ME effect in noncentrosymmetric AFM insulators. Although this phenomenon does not occur in gapped electron systems owing to the Mott relation 22 , we show that it occurs by magnons in a magnetic insulator whose unit cell contains multiple magnetic ions with different g factors. We emphasize that although the gravito-ME effect is an analog of the ME effect, these two phenomena may have essentially different origins.…”

mentioning

confidence: 64%

Magnon gravitomagnetoelectric effect in noncentrosymmetric antiferromagnetic insulators

Shitade

Yanase

2019

Self Cite

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

“…where B(r) varies slowly in space, i.e., on a length scale much larger than the lattice constant. The dipole moment can then be found from a thermodynamic relation [56]…”

Section: Linear Response Theorymentioning

confidence: 99%

Magnonic analog of the Edelstein effect in antiferromagnetic insulators

Mook

Raeliarijaona

et al. 2020

We investigate the nonequilibrium spin polarization due to a temperature gradient in antiferromagnetic insulators, which is the magnonic analogue of the inverse spin-galvanic effect of electrons. We derive a linear response theory of a temperature-gradient-induced spin polarization for collinear and noncollinear antiferromagnets, which comprises both extrinsic and intrinsic contributions. We apply our theory to several noncentrosymmetric antiferromagnetic insulators, i.e., to a one-dimensional antiferromagnetic spin chain, a single layer of kagome noncollinear antiferromagnet, e.g., KFe3(OH)6(SO4)2, and a noncollinear breathing pyrochlore antiferromagnet, e.g., LiGaCr4O8.