Plasmon excitation in graphene layers

S. SEGUI; J. L. GERVASONI; Z. L. MISKOVIC; N. R. ARISTA

Cracovia

Conferencia; NanoSmat 2011 6th. International Conference on Surfaces, Coatings and Nanostructured Materials; 2011

Nanosmat

The discovery of graphene monolayers and the relevance of their potential applications hasstimulated the interest in describing its electronic properties, and in particular those thatdistinguish it from graphite. Electron energy loss experiments provide a way to studyelectronic structure of solids and are specially useful for characterizing surfaces andnanostructures [1]. In addition, the low energy-loss part of an spectrum, dominated bycollective (plasmon) excitations, is very sensitive to the geometry of the sample. In thiswork we give a brief description of the excitation of plasmons due to the incidence of acharged particle on a graphene monolayer. We reformulate the quantized 2D two-fluidshydrodynamic model previously developed for SWNT [2], to describe the planar geometry.We calculate the dispersion relation of characteristic plasmon modes, and the averagenumber of plasmons excited for trajectories of the incident particle, corresponding todifferent experimental situations. With this, we are able to obtain the energy lossprobability for a particle passing through or reflecting from a graphene layer and comparethem with experimental spectra. We also compare the results with those obtained fromgraphite using the dielectric response model [3].[1] T Eberlein, U. Bangert. R.R. Nair, R. Jones, M. Gass, A. L. Bleloch, K. S. Novoselov, A.Geim, P. Briddon, Phys. Rev. B 77, 233406 (2008); Y. Liu, R. F. Willis, K. V. Emtsev, Th.Seyller, Phys. Rev. B 78 201403(R) (2008).[2] D. J. Mowbray, S Segui, J. L. Gervasoni, Z. L. Miskovic and N. R. Arista, PhysicalReview B 82, 035405 (2010).[3] C. Denton, J. L. Gervasoni, R. O. Barrachina and N. R. Arista. Journal of Physics C:Condensed Matter, A277 (1993).