Atomic friction experiments on flat surfaces have provided valuable information towards understanding fundamental friction laws.  In this study, we examine the complexity of atomic-scale friction by considering the effects of an atomic step on the surface.  Atomic steps have been shown to have a negligible effect on the friction observed at these step edges in certain instances, but in other cases can show increased dissipation compared to the surrounding terraces.  Typically this higher friction is attributed to the enhanced coordination of the atoms at the step edge, referred to as the Schwoebel barrier, with an atomic force microscope (AFM) tip.  Through experiments, analytical models, and molecular dynamic (MD) simulations, we propose that two distinct mechanisms affect the lateral force at the step, one being conservative (resulting from step geometry), and the other is dissipative (resulting from the Schwoebel effect), and find that the relative magnitude of each can be affected by the tip size and environment.

Atomic step edge effects on friction

244th National Meeting (2012)

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