Despite intensive investigations, the comprehension of the mechanisms ruling the interplay of charge doping, electron–phonon coupling and dynamic screening in supported graphene remains elusive yet. Using a combination of surface-science spectroscopies, we have studied these phenomena for graphene on both Pt-skin-terminated and nickel-oxide-skin-terminated Pt 3 Ni(1 1 1). Graphene epitaxially grown on the (1 1 1)-oriented Pt skin behaves as a charge-neutral graphene/metal contact, exhibiting a reduced coupling of the out-of-plane optical phonon with Dirac-cone electrons. Conversely, p-doped graphene/Pt(1 1 1) exhibits giant Kohn anomalies arising from the electron–phonon coupling. Upon oxidation, the Pt skin of Pt 3 Ni(1 1 1) evolves into a nickel-oxide skin, which results into a p-type doped graphene sheet. The plasmonic spectrum shows dramatic changes when going from a graphene/Pt-skin/Pt 3 Ni to a graphene/nickel-oxide/Pt 3 Ni configuration. Finally, we show that the presence of Ni atoms in the metal alloy does not affect the temperature at which the graphene phase is formed, contrarily to the interpretation of previous experiments.
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|Titolo:||Graphene on Pt 3 Ni(1 1 1): A suitable platform for tunable charge doping, electron–phonon coupling and plasmonic excitations|
|Data di pubblicazione:||2017|
|Appare nelle tipologie:||1.1 Articolo in rivista|