Strong spin-orbit splitting in graphene with adsorbed Au atoms

Spin-orbit (SO) splitting in graphene with adsorbed Au atoms is investigated by using a first-principles method. Considerable (similar to 200 meV) Rashba-type SO splitting can be achieved in the graphene pi bands. When a Au atom is adsorbed above a C-C bond, Dresselhaus-type SO splitting is found to be present due to the absence of inversion symmetry and the substantial contribution of Au 5d(xz) components. The influence of strains in graphene on SO splitting is also explored. A slight strain with the strength of -5% to 5% usually does not change much the SO splitting. The variation of SO splitting versus strain strength is rationalized through structural relaxation and effective hybridization between C 2p(z) and certain Au 5d states. Our study predicts a new way to increase the SO splitting in graphene and provides useful understanding of the mechanism. (C) 2011 Elsevier Ltd. All rights reserved.