Spin precession, flips, and transmission through a ring: Relation between the spin–orbit interaction strengths and the final spin orientation

We study spin precession and transmission through a mesoscopic ring in the presence of the Rashba and Dresselhaus terms of the spin–orbit interaction (SOI), respectively, of strengths α and β, and of a magnetic field B. The Rashba field, the effective Dresselhaus field as well as B have perpendicular and radial components. The final spin orientations depend importantly on α, β, and B. In the absence of B the outgoing spins trace rings perpendicular to well-defined directions for β=0 or α=0. For β=0(α=0) incident spins polarized along these well-defined directions exit the ring undeflected. For α≠β≠0 the trace rings become spirals. The values of α and β are related to the final spin orientation. For weak magnetic fields this precession picture does not hold. Spin flips occur when α or β is varied as the angles describing the final spin orientation change drastically in a very narrow range of α or β values in which the total transmission vanishes.