Spin Polarization by Current

Authored by: Sergey D. Ganichev , Maxim Trushin , John Schliemann

Handbook of Spin Transport and Magnetism

Print publication date:  August  2011
Online publication date:  April  2016

Print ISBN: 9781439803776
eBook ISBN: 9781439803783
Adobe ISBN:


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Spin generation and spin currents in semiconductor structures lie at the heart of the emerging field of spintronics and are a major and still-growing direction of solid-state research. Among the plethora of concepts and ideas, current-induced spin polarization (CISP) has attracted particular interest from both experimental and theoretical point of view, for reviews see Refs. [19]. In nonmagnetic semiconductors or metals belonging to the gyrotropic point groups, * dc electric current is generically accompanied by a nonzero average nonequilibrium spatially homogeneous spin polarization and vice versa. The latter phenomenon is referred to as the spin-galvanic effect (see, e.g., Refs. [5,7,1013]). In low-dimensional semiconductor structures, these effects are caused by asymmetric spin relaxation in systems with lifted spin degeneracy due to k-linear terms in the Hamiltonian, where k is the electron wave vector. In spite of the terminological resemblance, spin polarization by electric current fundamentally differs from the spin Hall effect [46,8,1420], which refers to the generation of a pure spin current transverse to the charge current and causes spin accumulation at the sample edges. The distinctive features of the CISP are that this effect can be present in gyrotropic media only, it results in nonzero average spin polarization, and does not depend on the space coordinates. Thus, it can be measured in the whole sample under appropriate conditions. The spin Hall effect, in contrast, does not yield average spin polarization and does not require gyrotropy, at least for the extrinsic spin Hall effect.

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