Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin

Abstract

The excitation spectrum in the region of the intraband (Dirac plasmon) and interband ( π plasmon) plasmons in graphene/Pt-skin terminated Pt 3 Ni(111) is reproduced by using an ab-initio method and an empirical model. The results of both methods are compared with experimental data. We discover that metallic screening by the Pt layer converts the square-root dispersion of the Dirac plasmon into a linear acoustic-like plasmon dispersion. In the long-wavelength limit, the Pt d electron excitations completely quench the π plasmon in graphene at about 4.1 eV, that is replaced by a broad peak at about 6 eV. Owing to a rather large graphene/Pt-skin separation (≈3.3 Å), the graphene/Pt-skin hybridization becomes weak at larger wave vectors, so that the π plasmon is recovered with a dispersion as in a free-standing graphene.

Surface plasmons on Pd(110): An ab initio calculation

“…Furthermore, the Pd surfaces present several surface states in the vicinity of the Fermi level [47][48][49]. We investigate whether their existence can lead to the realization of an additional low-energy surface mode -an acoustic surface plasmon [50] -observed on other surfaces supporting surface electronic states [30,[51][52][53][54][55][56][57][58].…”