Abstract
Even though graphene is a low-energy system consisting of a two-dimensional honeycomb lattice of carbon atoms, its quasiparticle excitations are fully described by the -dimensional relativistic Dirac equation. In this paper we show that, while the spin-orbit interaction in graphene is of the order of , it opens up a gap of the order of at the Dirac points. We present a first-principles calculation of the spin-orbit gap, and explain the behavior in terms of a simple tight-binding model. Our result also shows that the recently predicted quantum spin Hall effect in graphene can occur only at unrealistically low temperature.
- Received 5 December 2006
DOI:https://doi.org/10.1103/PhysRevB.75.041401
©2007 American Physical Society