Electron spin-flip scattering in graphene due to substrate impurities

Abstract

Graphene has long been known for its peculiar Dirac-like band structure which lends it many of its remarkable properties. It is a promising material for electronic and spintronic applications due to its high carrier mobility, low intrinsic spin-orbit interaction and small hyperfine coupling. However, extrinsic effects may easily dominate intrinsic mechanisms. The scattering mechanisms investigated here are those associated with non-magnetic, charged impurities in the substrate (e.g. SiO2) beneath a planar n-type graphene layer. Such impurities cause an electric field that extends through the graphene and has a non-vanishing perpendicular component. Consequently, the impurity, in addition to the conventional spin-conserving scattering can give rise to spin-flip processes. The latter are a consequence of a spatially varying Rashba spin-orbit interaction caused by the electric field of the impurity in the substrate. This work focuses on the calculation of the elastic scattering cross-sections for these mechanisms. Additionally, relaxation times are estimated for assumed impurity concentrations.