Rashba-type spin accumulation near a void at a system edge

Abstract

We consider the spatial distribution of spin accumulation ${S}_{z}$ near a void (edge void) located at a system edge. The edge void is semicircular in shape with a radius ${R}_{0}\ensuremath{\approx}{l}_{\mathrm{so}}$, the spin-relaxation length, and it is formed out of a Rashba-type two-dimensional electron system in the diffusive regime. The nonuniform driving field provides the essential condition, and diffusive contributions to the spin currents from spin polarizations provide the primary impetus for the spin accumulation. The edge void reveals an underlying asymmetry of the bulk-void counterpart, namely, a finite bulklike spin flow at the system edge. This bulklike spin flow gives rise to spin accumulation when open boundary occurs. The bulklike spin flow is found to exhibit a similar spatial profile as that of ${S}_{z}$ at the system edge. This bulklike spin flow is expected to be a primary impetus for local spin injection at the sample edge near the edge void when a local protrusion occurs. Spin orientation of the bulklike spin flow varies with the locations on the edge-void boundary.