Intrinsic Spin-Hall Effect in 2D Electron Systems

Eugene Mishchenko
Department of Physics, University of Utah

Conventional Hall effect is manifested by the accumulation of electric charges at the edges of a conductor placed in a magnetic field when electric current is driven through it. Spin-Hall effect is a spin analog of the Hall effect: in the presence of electric current spins of different directions may be driven to the opposite edges of a conductor. This effect occurs as a result of spin-orbital interaction which couples electron spin to its momentum. Spin-Hall effect can be extrinsic (due to impurities) or intrinsic (due to band structure). I will present an overview of basic theoretical concepts of Spin-Hall Effect as well as address several existing experiments. Intrinsic Spin-Hall effect originally predicted to be universal in a 2D electron gas -- independent of the strength of spin-orbit coupling -- turned out to be destroyed by an arbitrarily small disorder in any steady state of an infinite 2DEG. Is it possible to have non-vanishing spin-Hall effect in case of a mesoscopic system with the size less that the mean free path and to which extent will the effect be really universal? We find that the net spin polarization across the edge of the conductor is second order in spin-orbit coupling constant independent of the form of the boundary potential.