Spin-Hall effect in a finite two-dimensional electron gas sample with a central defect

We study spin and charge accumulation in two-dimensional electron gas (2DEG) with spin-orbit Rashba interactions. The Landauer-Keldysh formalism is employed to numerically compute accumulations in a 2DEG finite square sample with and without an embedded spin-independent hard-wall impurity. Cases with two and four attached ideal leads are considered. We find that in the two directions perpendicular to the Rashba field the impurity induces, respectively, a dipole and a quadrupole. In the direction parallel to the Rashba field the spin accumulation is determined purely by the imposed boundary conditions. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3067411].