Spin polarization of electron current through a potential barrier in two-dimensional structures with spin-orbit interaction.

We show that an initially unpolarized electron flow acquires spin polarization after passing through a lateral barrier in a two-dimensional (2D) system with spin-orbit interaction (SOI) even if the current is directed normally to the barrier. The generated spin current depends on the distance from the barrier. It oscillates with the distance in the vicinity of the barrier and asymptotically reaches a constant value. The most efficient generation of the spin current (with polarization above 50%) occurs when the Fermi energy is near the potential barrier maximum. Since the spin current in the SOI medium is not unambiguously defined, we propose to pass this current from the SOI region into a contacting region without SOI and show that the spin polarization loss under such transmission can be negligible.