High Van Hove singularity extension and Fermi velocity increase in epitaxial graphene functionalized by gold clusters intercalation

Gold intercalation between the buffer layer and a graphene monolayer of epitaxial graphene on SiC(0001) leads to the formation of quasi free standing small aggregates of clusters. Angle Resolved Photoemission Spectroscopy measurements reveal that these clusters preserve the linear dispersion of the graphene quasiparticles and surprisingly increase their Fermi velocity. They also strongly modify the band structure of graphene around the Van Hove singularities (VHs) by a strong extension without charge transfer. This result gives a new insight on the role of the intercalant in the renormalization of the bare electronic band structure of graphene usually observed in Graphite and Graphene Intercalation Compounds.

Superlattice of resonators on monolayer graphene created by intercalated gold nanoclusters

Here we report on a new type of ordering which allows to modify the electronic structure of a graphene monolayer (ML). We have intercalated small gold clusters between the top monolayer graphene and the buffer layer of epitaxial graphene. We show that these clusters perturb the quasiparticles on the ML graphene, and act as quantum dots creating a superlattice of resonators on the graphene ML, as revealed by a strong pattern of standing waves. A detailed analysis of the standing wave patterns using Fourier Transform Scanning Tunneling Spectroscopy strongly indicates that this phenomenon can arise from a strong modification of the band structure of graphene and (or) from Charge Density Waves (CDW)where a large extension of Van Hove singularities are involved.