Time-lapsed graphene moir\'e superlattice on Cu(111)

The detailed study of the graphene (gr) moir\'e superlattices emerging due to the mismatch between the substrate's and gr-overlayer crystal lattices is inevitable because of its high technological relevance. However, little is known about the dynamics of moir\'e superstructures on gr. Here, we report the first classical molecular dynamics simulation (CMD) of the moir\'e superlattice of graphene on Cu(111) using a new parameterized Tersoff-potential for the graphene/Cu(111) interface fitted in this paper to nonlocal van der Waals density functional theory (DFT) calculations. The interfacial force field with time-lapsed CMD provides superlattices in good quantitative agreement with the available experimental results. The long range coincidence supercells of $2 \times 2$ and $3 \times 3$ with nonequivalent moir\'e hills have also been identified and analyzed. The moir\'e superlattice exhibits a pattern which is dynamical rather than statically pinned to the support and can be observed mostly via time lapsing. The instantaneous snapshots of the periodic moir\'e pattern already at low temperature are weakly disordered lacking the apparent sharpness of the time averaged pattern and scanning tunneling microscopy images. This suggests the existence of competing orders between a static (1st order) and a dynamical (2nd order) moir\'e superstructures.The revealed random height fluctuations may limit the important electronic properties of supported graphene such as the mobility of charge carriers.Comment: 14 pages, 8 figures, supplementary material included. arXiv admin note: text overlap with arXiv:1401.171