Plasmons in monolayer and bilayer graphene

Abstract

The collective oscillations of electrons in monolayer and bilayer graphene show different characteristics from those in ordinary two-dimensional Fermi gases. The chirality of the electrons in graphene sets up extra selection rules to their dynamics. The unconventional energy dispersion relation in graphene modifies the electron movement. The narrow gap encourages the carrier exchange between the conduction and the valence bands. The competition between the intra- and the inter-band interactions may introduce extra plasmon branches. The potential bias between the sublattices in monolayer graphene and the monolayers in bilayer graphene opens gap in the electron-hole single particle continuum. Undamped plasmon modes with almost zero group velocity may appear in the gap.