EELS study of the epitaxial graphene/Ni(111) and graphene/Au/Ni(111) systems

TL;DR

This study uses electron energy-loss spectroscopy to analyze the electronic structure changes in graphene when placed on Ni(111) and after gold intercalation, revealing transitions from strongly bonded to quasi free-standing graphene states.

Contribution

It provides new insights into how gold intercalation modifies the electronic properties of graphene on Ni(111), demonstrated through EELS spectral analysis.

Findings

Reduced c6c6 plasmon dispersion in graphene/Ni(111)

Disappearance of characteristic EELS features after gold intercalation

Shift of c6c6 plasmon indicating transition to quasi free-standing graphene

Abstract

We have performed electron energy-loss spectroscopy (EELS) studies of Ni(111), graphene/Ni(111), and the graphene/Au/Ni(111) intercalation-like system at different primary electron energies. A reduced parabolic dispersion of the \pi plasmon excitation for the graphene/Ni(111) system is observed compared to that for bulk pristine and intercalated graphite and to linear for free graphene, reflecting the strong changes in the electronic structure of graphene on Ni(111) relative to free-standing graphene. We have also found that intercalation of gold underneath a graphene layer on Ni(111) leads to the disappearance of the EELS spectral features which are characteristic of the graphene/Ni(111) interface. At the same time the shift of the \pi plasmon to the lower loss-energies is observed, indicating the transition of initial system of strongly bonded graphene on Ni(111) to a quasi free-standing-like graphene state.