Spin-relaxation suppression by compensation of bulk and structural inversion asymmetries in [111]-oriented quantum wells

We investigate the feasibility of compensating the bulk inversion asymmetry in a [111]-oriented quantum well with the Rashba structure inversion asymmetry that has precisely the same functional form. The resulting cancellation is found to provide a promising means for strongly suppressing the spin-relaxation rate associated with the D'yakonov-Perel' (DP) mechanism. We discuss a detailed numerical study of the spin splitting in a suitable InAlAs/InGaAs/InP quantum well grown on a [111] InP substrate, for which an external electric field is used to fine tune the asymmetry. We show that the DP spin-relaxation rate can be suppressed by nearly an order of magnitude at room temperature and by a factor of 2000 at 10 K. (C) 2005 American Institute of Physics.