  Spin dephasing via the spin-orbit interaction (SOI) is a major mechanism
limiting the electron spin lifetime in III-V zincblende quantum wells. The
dephasing can be suppressed in GaAs(111) quantum wells by applying an electric
field. The suppression has been attributed to the compensation of the intrinsic
SOI associated by the bulk inversion asymmetry (BIA) of the GaAs lattice by a
structural induced asymmetry (SIA) SOI term induced by an electric field. We
provide direct experimental evidence for this mechanism by demonstrating the
transition between the BIA-dominated to a SIA-dominated regime via
photoluminescence measurements carried out over a wide range of applied fields.
Spin lifetimes exceeding 100~ns are obtained near the compensating electric
field, thus making GaAs (111) QWs excellent candidates for the electrical
storage and manipulation of spins.
