title: Plasmon electron-hole resonance in epitaxial graphene.
abstract: The quasiparticle dynamics of the sheet plasmons in epitaxially grown graphene layers on SiC(0001) has been studied systematically as a function of temperature, intrinsic defects, influence of multilayers and carrier density using electron energy loss spectroscopy with high energy and momentum resolution. The opening of an inter-band decay channel appears as an anomalous kink in the plasmon dispersion which we describe as a resonance effect in the formation of electron-hole pairs. Due to the inevitable strong coupling of plasmons with single particle excitations in reduced dimensions, such signatures are generally expected.
authors.affiliation: Institut für Festkörperphysik, Leibniz-Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany. tegenkamp@fkp.uni-hannover.de
authors.forename: C
authors.initials: C
authors.lastname: Tegenkamp
authors.forename: H
authors.initials: H
authors.lastname: Pfnür
authors.forename: T
authors.initials: T
authors.lastname: Langer
authors.forename: J
authors.initials: J
authors.lastname: Baringhaus
authors.forename: H W
authors.initials: HW
authors.lastname: Schumacher