Spin orientation and spin precession in inversion-asymmetric quasi-two-dimensional electron systems

Inversion-asymmetry-induced spin splitting of the electron states in quasi-two-dimensional (quasi-2D) systems can be attributed to an effective magnetic field B which varies in magnitude and orientation as a function of the in-plane wave vector k_. Using a realistic 8×8 Kane model that fully takes into account spin splitting because of both bulk inversion asymmetry and structure inversion asymmetry we investigate the spin orientation and the effective field B for different configurations of a quasi-2D electron system. It is shown that these quantities depend sensitively on the crystallographic direction in which the quasi-2D system was grown as well as on the magnitude and orientation of the in-plane wave vector k_. These results are used to discuss how spin-polarized electrons can precess in the field B(k_). As a specific example we consider Ga0.47{In}0.53As{-}InP$ quantum wells.