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 (～200 meV) Rashba-type SO splitting can be achieved in the graphene π 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.