Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 50: Graphene (organized by O)

TT 50.13: Poster

Tuesday, March 17, 2015, 18:15–21:00, Poster A

Phonon-Plasmon-Coupling in Bilayer Graphene on 6H-SiC(0001) — •Christian Heidrich, Sindy Franz, Roland Koch, and Thomas Seyller — Institut für Physik, TU Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany

Understanding the interaction between phonons and charge carriers of graphene is of high relevance from a fundamental as well as from an application point of view. Here we report on a study of bilayer epitaxial graphene on SiC(0001) using high resolution electron energy-loss spectroscopy (HREELS). This surface sensitive method is useful for the investigation of phonon vibrations, plasmon excitations, and the coupling of both. It is also possible to study the dispersion of these phenomena over the whole Brillouin zone by varying the scattering geometry. Changing the primary beam energy on the other hand enables measuring those dispersion relations very close to the center of the Brillouin zone. Here we employ the latter to study the coupling of graphene's free charge carrier plasmon to phonons in the substrate as well as graphene itself in the dipole scattering regime. Using dielectric theory calculations, we simulated our measurements and the dispersion relation for the coupled phonon plasmon modes to compare with the experiment.