Dispersion and damping of the interband pi plasmon in graphene grown on Cu(111) foils

作者：Politano A; Radovic I; Borka D; Miskovic Z L; Yu H K; Farias D; Chiarello G

来源：Carbon, 2017, 114: 70-76.

DOI：10.1016/j.carbon.2016.11.073

By means of angle-resolved electron energy loss spectroscopy, we have measured the interband it plasmon in high-quality graphene grown on peeled-off epitaxial Cu(111) foils. Experimental loss spectra have been reproduced by means of a hydrodynamic model. The dispersion relation of the plasmon frequency shows a nearly-flat dispersion up to a critical wave-vector of 0.3 angstrom(-1). We propose that the observed behavior could be originated by confinement effects in ripples in the strained graphene sheet. Strain also limits the dispersion at higher momenta, as a consequence of the increased effective mass of charge carriers. The analysis of momentum dependence of the line-width and of the inverse quality factor indicates that damping processes are dominated by decay in electron-hole pairs via indirect interband transitions.

• 出版日期2017-4