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Type: 
Journal
Description: 
By means of angle-resolved electron energy loss spectroscopy, we have measured the interband π 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 Å−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.
Publisher: 
Pergamon
Publication date: 
1 Apr 2017
Authors: 

A Politano, Ivan Radović, Duško Borka, ZL Mišković, HK Yu, D Farías, G Chiarello

Biblio References: 
Volume: 114 Pages: 70-76
Origin: 
Carbon