Rashba effect originates from the reduction of point-group symmetries

Abstract

The Rashba effect in a nonmagnetic condensed-matter system is described by the reduction of point-group symmetries. The inversion, two-fold rotation, and reflection symmetries transforming the wavevector k to −k are identified as the origin of a degenerate state according to the time-reversal symmetry. The lack of these symmetries in a bulk system or the breaking of these in a surface system is then identified as the origin of a nondegenerate state. The surface systems Au(111), Au(110), and W(110) are assessed. The bulk system BiTeI is demonstrated for the existence of a nondegenerate state on the basis of first-principles calculations. The related issues of the heterostructure GaAs/AlGaAs and the spin Hall effect are also presented.