Analysis of atomic Moiré patterns on graphene/Rh(1 1 1)

Abstract

In scanning tunneling microscopy the lattice mismatch between graphene and Rh(1 1 1) is observed as an additional superstructure. This superstructure is called Moiré pattern. Various symmetry sites occur in a Moiré pattern. These are distinguished by the arrangement of the graphene lattice over the Rh(1 1 1) lattice.

The symmetry sites of the Moiré unit cell are investigated by scanning tunneling microscopy and spectroscopy. The observed additional corrugation of the graphene sheet within a Moiré cell is the consequence of strain and electronic interactions between graphene and the Rh(1 1 1) substrate. The lattice period of the Moiré pattern depends on the in-plane rotation angle of the graphene layer with respect to the Rh(1 1 1) substrate. Scanning tunneling spectroscopy reveals a dependency of the local density of states on the hybridization of the π orbitals of the graphene with the d band of Rh(1 1 1). This results in a characteristic spectroscopic fingerprints of the individual symmetry sites of the Moiré pattern.