Filtering of spin currents based on a ballistic ring

Abstract

Quantum interference effects in rings provide suitable means for controlling spin at mesoscopic scales. Here we apply such a control mechanism to the spin dependent transport in a ballistic quasi-one-dimensional ring patterned in two-dimensional electron gases (2DEGs). The study is essentially based on the natural spin-orbit (SO) interactions, one arising from the laterally confining electric field (β term) and the other due to the quantum well potential that confines electrons in the 2DEG (conventional Rashba SO interaction or α term). We focus on single-channel transport and solve analytically for the spin polarization of the current. As an important consequence of the presence of spin splitting, we find the occurrence of spin dependent current oscillations. We analyze the transport in the presence of one non-magnetic obstacle in the ring. We demonstrate that a spin polarized current can be induced when an unpolarized charge current is injected in the ring, by focusing on the central role that the presence of the obstacle plays. © IOP Publishing Ltd.