The Berry phase in graphene and graphite multilayers

Abstract

We discuss the electron energy spectra and the Berry phases for graphene, a graphite bilayer, and bulk graphite, allowing for a small spin-orbit interaction. If an electron orbit in the Brillouin zone surrounds several Dirac points (band-contact lines in graphite), one can find the relative signs of the Berry phases generated by these points (lines) by taking this interaction into account.