The spin galvanic effect

Abstract

The spin-galvanic effect is a transfer of the non-equilibrium electron spin polarization into a translational motion of free charge carriers. This spin-to-current conversion is allowed by the symmetry of the gyrotropic point groups which make no difference between some components of polar and axial vectors. We consider different mechanisms of the spin-galvanic effect, particularly, the kinetic and relaxational, that are determined by instantaneous values of the spin polarization and its time derivative, respectively. The gyrotropic symmetry allows as well the inverse spin-galvanic effect, or current-to-spin conversion. We review the basic experiments on the direct and inverse spin-galvanic effects which can be observed in various gyrotropic semiconductor systems and ferromagnet/semiconductor bilayers, at metal surfaces or interfaces and surfaces of topological insulators.