Coulomb interaction effects in graphene bilayers: Electron-hole pairing and plasmaron formation

Abstract

We report a theoretical study of the many-body effects of electron-electron interaction on the ground-state and spectral properties of double-layer graphene. Using a projector-based renormalization method we show that if a finite-voltage difference is applied between the graphene layers, electron-hole pairs can be formed and-at very low temperatures-an excitonic instability might emerge in a double-layer graphene structure. The single-particle spectral function near the Fermi surface exhibits a prominent quasiparticle peak different from neutral (undoped) graphene bilayers. Away from the Fermi surface we find that the charge carriers strongly interact with plasmons thereby giving rise to a broad plasmaron peak in the angle-resolved photoemission spectrum. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.