Diffusive Spin Transport In Narrow Two-Dimensional-Electron-Gas Channels

Using the geometry of the spin field-effect transistor, we investigate the spin transport of in-plane spins in an array of narrow channels formed in a two-dimensional electron gas confined in an (In, Ga)As quantum well. We demonstrate a clear enhancement of the spin-diffusion length with decreasing channel width, yielding up to 10 mu m for the narrowest channels. We discuss the observed enhancement in terms of the suppression of the Dyakonov-Perel mechanism of spin relaxation, which has been invoked in previous studies in the case of diffusion of out-of-plane oriented spins. We also show that the spin signal is significantly higher when injecting into an array of narrow channels, compared with injecting into a single narrow channel.