Friction at atomic-scale surface steps: experiment and theory.
Experiments performed by friction force microscopy at atomic-scale surface steps on graphite, MoS2, and NaCl in ambient conditions are presented. Both step-down and step-up scans exhibit higher frictional forces at the edge, but distinguish in their load dependence: While the additional frictional force due to the step edge increases linearly with load if the tip has to jump a step up, it remains constant for downward jumps. This phenomenon represents a universal effect that can be explained in terms of a modified Prandtl-Tomlinson model featuring a Schwoebel-Ehrlich barrier at steps.
Hölscher
Hendrik
H
Institute for Microstructure Technology, Forschungszentrum Karlsruhe, P.O. Box 3670, 76021 Karlsruhe, Germany. hendrik.hoelscher@imt.fzk.de
Ebeling
Daniel
D
Schwarz
Udo D
UD