Robust Superlubricity in Graphene/h-BN Heterojunctions.

The sliding energy landscape of the heterogeneous graphene/h-BN interface is studied by means of the registry index. For a graphene flake sliding on top of h-BN, the anisotropy of the sliding energy corrugation with respect to the misfit angle between the two naturally mismatched lattices is found to reduce with the flake size. For sufficiently large flakes, the sliding energy corrugation is expected to be at least an order of magnitude lower than that obtained for matching lattices regardless of the relative interlayer orientation. Therefore, in contrast to the case of the homogeneous graphene interface where flake reorientations are known to eliminate superlubricty, here, a stable low-friction state is expected to occur. Our results mark heterogeneous layered interfaces as promising candidates for dry lubrication purposes.