Electric-field control of spin-orbit splittings in GaAs/AlxGa1-xAs coupled quantum wells

Electron spin dynamics is investigated in n-i-n GaAs/AlGaAs coupled quantum wells. The electron-spin dephasing time is measured as a function of an external electrical bias under resonant excitation of the 1sHH intrawell exciton using a time-resolved Kerr rotation technique. There is found a strong electron-spin dephasing time anisotropy caused by an interference of the structure inversion asymmetry and the bulk inversion asymmetry. This anisotropy is shown to be controlled by an electrical bias. A theoretical analysis of electron-spin dephasing time anisotropy is developed. The ratio of Rashba and Dresselhaus spin splittings is studied as a function of applied bias.