Accumulation of opposite spins on the transverse edges of a two-dimensional electron gas in a longitudinal electric field

We show that the spin-orbit interaction induced by the boundary-confining potential causes opposite spin accumulations on the transverse edges in a zonal two-dimensional electron gas in the presence of an external longitudinal electric field. While the bias is reversed, the spin-polarized direction is also reversed. The intensity of the spin accumulation is proportional to the bias voltage. In contrast to the bulk extrinsic and intrinsic spin-Hall effects, the spin accumulation by the confining potential is almost unaffected by impurity and survives even in strong disorder. The result provides a different mechanism to explain the recent experimental data.