Quasi-one-dimensional nature of the Rashba states of Au wires on Si(5Â 5Â 7) surface

The electronic band structure of Si(5 5 7) surface adsorbed with Au wires is studied by means of first-principles density-functional-theory calculations. The spin-orbit split metallic bands are associated with the Au-Si zigzag chain and their asymmetric electron density around the Au atoms due to the on-site orbital hybridization explain large Rashba-type splitting and out-of-plane spin polarization. It is found that the Rashba metallic states have strong one-dimensional (1D) character along the Au wires but non-negligible two-dimensional distribution of the wave functions, implying not exactly genuine, only quasi 1D states.