paper

Formation of image-potential states at the graphene/metal interface

arXiv:1507.02882 · doi:10.1088/1367-2630/17/10/103043

Abstract

The formation of image-potential states at the interface between a graphene layer and a metal surface is studied by means of model calculations. An analytical one-dimensional model-potential for the combined system is constructed and used to calculate energies and wave functions of the image-potential states at the Gamma-point as a function of the graphene-metal distance. It is demonstrated how the double series of image-potential states of free-standing graphene evolves into interfacial states that interact with both surfaces at intermediate distances and finally into a single series of states resembling those of a clean metal surface covered by a monoatomic spacer layer. The model quantitatively reproduces experimental data available for graphene/Ir(111) and graphene/Ru(0001), systems which strongly differ in interaction strength and therefore adsorption distance. Moreover, it provides a clear physical explanation for the different binding energy and lifetime of the first (n=1) image-potential state in the valley and hill areas of the strongly corrugated moire superlattice of graphene/Ru(0001).

16 pages, 4 figures, * added comparison with DFT calculations (Ref.[19]) in section 3, * added references ([3-4] and [42-44]), * unify the use of energy and binding energy throughout the text, * corrected typos and grammar

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