Superlubric to stick-slip sliding of incommensurate graphene flakes on graphite
M. M. van Wijk, M. Dienwiebel, J. W. M. Frenken, A. Fasolino
Phys. Rev. B, 88, (2013), 235423
We calculate the friction of fully mobile graphene flakes sliding on graphite. For incommensurately stacked flakes, we find a sudden and reversible increase in friction with load, in agreement with experimental observations. The transition from smooth sliding to stick-slip and the corresponding increase in friction is neither due to rotations to commensurate contact nor to dislocations but to a pinning caused by vertical distortions of edge atoms also when they are saturated by hydrogen. This behavior should apply to all layered materials with strong in-plane bonding.