We show that the Rashba spin-orbit interaction contributes to edge spin accumulation $S_z$ in a diffusive regime when the driving field is nonuniform. Specifically, we solve the case of nonuniform driving field in the vicinity of a circular void locating in a two-dimensional electron system and we identify the key physical process leading to the edge spin accumulation. The void has radius $R_0$ in the range of spin-relaxation length $l_{\text{so}}$ and is far from both source and drain electrodes. The key physical process we find is originated from the nonuniform in-plane spin polarizations. Their subsequent diffusive contribution to spin current provides the impetus for the edge spin accumulation $S_z$ at the void boundary. The edge spin accumulation is proportional to the Rashba coupling constant $\alpha$ and is in a spin-dipole form oriented transversely to the driving field. We expect similar spin accumulation to occur if the void is at the sample edge.

• Received 11 February 2010

DOI:https://doi.org/10.1103/PhysRevB.81.115312