Rotation misorientated graphene moire superlattices on Cu (111): Classical molecular dynamics simulations and scanning tunneling microscopy studies

摘要

Graphene on copper is a system of high technological relevance, as Cu is one of the most widely used substrates for the CVD growth of graphene. However, very little is known about the details of their interaction. One approach to gain such information is studying the superlattices emerging due to the mismatch of the two crystal lattices. However, graphene on copper is a low-corrugated system making both their experimental and theoretical study highly challenging. Here, we report the observation of a new rotational moire super-lattice of CVD graphene on Cu (111), characterized by a periodicity of (1.5 ± 0.05) nm and corrugation of (0.15 ±0.05) A, as measured by scanning tunneling microscopy (STM). To understand the observed superlattice we have developed a newly parameterized Abell-Tersoff potential for the graphene/Cu (111) interface fitted to nonlocal van der Waals density functional theory (DFT) calculations. The interfacial force field with time-lapsed classical molecular dynamics (CMD) provides superlattices in good quantitative agreement with the experimental results, for a misorientation angle of (10.4 ±0.5°), without any further parameter adjustment. Furthermore, the CMD simulations predict the existence of two non-equivalent high-symmetry directions of the moire pattern that could also be identified in the experimental STM images.