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 αα and ββ, 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 αα, ββ, and B. In the absence of B   the outgoing spins trace rings perpendicular to well-defined directions for β=0β=0 or α=0α=0. For β=0β=0(α=0)(α=0) incident spins polarized along these well-defined directions exit the ring undeflected. For α≠β≠0α≠β≠0 the trace rings become spirals. The values of αα and ββ are related to the final spin orientation. For weak magnetic fields this precession picture does not hold. Spin flips occur when αα or ββ is varied as the angles describing the final spin orientation change drastically in a very narrow range of αα or ββ values in which the total transmission vanishes.