Light-modulated spin precession in a two dimensional spin field effect transistor

Perfect spin precession in a two dimensional electron gas is the basis of the Datta-Das spin field effect transistor. However, in a two dimensional system this ideal spin precession can be washed out by the intersubband mixing effects induced by the Rashba spin–orbit interaction. Here, we propose by applying an off-resonant linearly polarized light a perfect spin modulation of conductance can be demonstrated in a two dimensional spin field effect transistor. This is because in a two dimensional electron gas due to the renormalization of the Rashba spin–orbit coupling strength and the hopping amplitude by the light, the intersubband mixing effects can be weakened. For an appropriate intensity of the light, the intersubband mixing effects are completely suppressed. These phenomena provide a promising way to design an optically-controlled spintronics device. (paper)