��-Plasmon Dispersion in Free-Standing Graphene by Momentum-Resolved Electron Energy-Loss Spectroscopy

Autor:	Liou, S. C., Shie, C. -S., Chen, C. H., Breitwieser, R., Pai, W. W., Guo, G. Y., Chu, M. -W.
Rok vydání:	2014
Předmět:	Strongly Correlated Electrons (cond-mat.str-el) Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Physics::Atomic and Molecular Clusters Physics::Optics FOS: Physical sciences
DOI:	10.48550/arxiv.1412.8538
Popis:	The ��-plasmon dispersion in graphene was scrutinized by momentum(q)-resolved electron energy-loss spectroscopy with an improved q resolution and found to display the square root of q dispersion characteristic of the collective excitation of two-dimensional electron systems, in contrast with previous experimental and theoretical studies which reported a linear q dispersion. Our theoretical elaborations on the q-dependent spectra affirm this square root of q relation and further unveil an in-plane electronic anisotropy. The physical property of the �� plasmon is thoroughly compared to that of the two-dimensional plasmon due to carriers of the Dirac fermions. A clear distinction between the �� plasmon and the two-dimensional Dirac plasmon was demonstrated, clarifying the common notion on correlating the linearly-dispersed Dirac cones to the linear dispersion of the �� plasmon previously reported. 20 pages, 6 figures, regular article, Physical Review B accepted 2014
Databáze:	OpenAIRE
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