A DFT study of the proximity effect in the spin-orbit coupling in Au/graphene, Au/silicene, and Bi/silicene bilayers

Abstract

The relativistic band structures of bilayers, built from graphene and silicene and monolayers of heavy atoms, Au and Bi, have been calculated within DFT. It is shown that when the orbital overlap is minor, like in the case of Au monolayer on graphene, a strong spin-orbit coupling in Au does not open a substantial gap in the Dirac cone. When, in contrast, the overlap of the wave functions is significant, like in the cases of Au and Bi adsorbed on silicene, the mixing of the bands (hybridization) destroys the cone structure and makes a separation of the bands by their origin or possession uncertain. In such cases, the spin-orbit splitting of the bands hardly could be attributed to a particular layer and corresponds to the band structure of the net layered system.