Dispersion and damping of the interband pi plasmon in graphene grown on Cu(111) foils
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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. (C) 2016 Elsevier Ltd. All rights reserved.
Izvor:Carbon, 2017, 114, 70-76
- Funkcionalni, funkcionalizovani i usavršeni nano materijali (RS-45005)
- COST Action [MP1306], Natural Sciences and Engineering Research Council of Canada [249506-2011], Spanish MINECO [MAT2015-65356-C3-3-R], Spanish MINECO through the Maria de Maeztu Programme for Units of Excellence in RD [MDM-2014-0377]