Spin relaxation in semiconductor mesoscopic systems

Phonon-assisted spin-flip transitions between the Zeeman sublevels are considered for two different mesoscopic systems: GaAs quantum dots (localized states) and the 2D electron system in the quantum Hall—regime for filling factor 1 (delocalized states). The phonon-assisted spin-flip rates for all spin–orbit-related mechanisms are evaluated. The role of the localization of the electron states in the effectiveness of the spin-lattice relaxation and the different role of the Coulomb interaction for these two systems are discussed. It is shown, for example, that spin-lattice relaxation for the electron localized in a quantum dot is much less effective than for the free electron. Besides, the spin-flip rates due to several other mechanisms not related to the spin–orbit interaction are estimated for the dot electron.