Anisotropic Rashba splitting of Au(110) surface states*

We investigate the surface Rashba effect subject to reduced in-plane symmetry. Based on a \textbf{K.p} perturbation theory, we give a detailed microscopic description of the Anisotropic Rashba Splitting (ARS). Furthermore, we show that this ARS can not be explained within the standard theoretical picture of the Rashba effect assuming a purely normal-to-surface variation of the crystal potential. The new microscopic expression for the Rashba Hamiltonian is explicitelly supported by fully relativistic first principles calculations for the case of unreconstructed Au(110) surface.