Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 31: Tribology

O 31.5: Talk

Tuesday, March 17, 2015, 15:00–15:15, MA 144

Puckering stick-slip friction induced by a sliding nanoscale contact on graphite — •Mircea V. Rastei, Benoit Heinrich, Pedro Guzman, and Jean-Louis Gallani — Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, F-67034 Strasbourg, France

We report on the experimental observation of puckering-induced nanoscale friction at a graphite surface [1,2]. Using an atomic force microscope operating in vacuum, we show that puckering effect induces nanoscale stick-slip processes originating from periodic deformations of the contact region followed by thermally activated relaxations. These processes are found to depend on the stiffness difference between the crystal axes, and on other tunable parameters such as sliding velocity. The angle between the sliding direction and the stiff crystallographic axis determines the periodicity of the slip events defining domains of various friction properties. We show that each domain presents a particular logarithmic dependence of friction with speed, indicating thermally assisted sliding regimes implying different potential barriers. The difference is proposed to arise from the way the tip interacts with the ridge of the puckered region, which in turn depends on local structural defects. The experimental data are interpreted using the rate theory, with specific potential barriers for each frictional domain. [1] M.V. Rastei, B. Heinrich and J.L. Gallani, Phys. Rev. Lett. 111, 084301 (2013) [2] M.V. Rastei, P. Guzman, J.L Gallani, Phys. Rev. B 90, 041409(R) (2014)