Spin-Hall Effect in Chiral Electron Systems: from Semiconductor Heterostructures to Topological Insulators

The phenomenon of mesoscopic Spin-Hall effect reveals in a nonequilibrium spin accumulation (driven by electric current) at the edges of a ballistic conductor or, more generally, in the regions with varying electron density. In this paper we review our recent results on spin accumulation in ballistic two-dimensional semiconductor heterostructures with Rashba/Dresselhaus spin orbit interactions, and extend the method developed previously to predict the existince of spin-Hall effect on the surface of three-dimensional topological insulators. The major difference of the new Spin-Hall effect is its magnitude, which is predicted to be much stronger than in semiconductor heterostructures. This happens because in semiconductors the spin accumulation appears due to a small spin-orbit interaction, while the spin-orbit constitutes a leading term in the Hamiltonian of topological insulator.