Spin relaxation anisotropy in two-dimensional semiconductor systems

Spin relaxation is investigated theoretically in two-dimensional systems. Various semiconductor structures of both n and p types are studied in detail. The most important spin relaxation mechanisms are considered. The spin relaxation times are calculated taking into account the contributions to the spin-orbit interaction due to the bulk inversion asymmetry and to the structure inversion asymmetry. It is shown that in-plane anisotropy of electron spin relaxation appears in III-V asymmetrical heterostructures. This anisotropy may be controlled by external parameters, and the spin relaxation times differ by several orders of magnitude.