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O: Fachverband Oberflächenphysik
O 120: Tribology: Surfaces and nanostructures
O 120.1: Talk
Friday, March 16, 2018, 11:30–11:45, MA 144
The Prandtl-Tomlinson model with time-varying interaction potential: Analytical predictions and experimental results — •Enrico Gnecco1, Andre Schirmeisen2, and Juan J. Mazo3 — 1Friedrich Schiller University Jena, Germany — 2Justus Liebig University Giessen, Germany — 3University of Zaragoza, Spain
The nonlinear Prandtl-Tomlinson (PT) model is possibly the simplest mechanism explaining the stick-slip motion of a sharp tip elastically pulled on a solid surface. In its basic version the PT model assumes uniform tip-surface interaction. Here we will assume that this is not the case and discuss the influence of contact oscillations and of a growing interaction strength due to "contact ageing" on the model results. In the former case the friction force is expected to decrease almost linearly with the oscillation amplitude until the stick-slip is replaced by steady sliding [1,2]. In the latter contact ageing results in a characteristic velocity weakening of friction which, in specific parameter ranges, can supersede the velocity strengthening caused by thermally activated stick-slip [3]. Interestingly, a similar approach can be used to reproduce the patterning process of compliant amorphous surfaces indented by a tip sliding on them [4]. The main predictions of the extended PT models are supported by experimental results on alkali halide and polymer surfaces in UHV and ambient conditions.
[1] R. Roth et al., App. Phys. Lett. 104, 083103 (2014). [2] O.Y. Fajardo et al., Phys. Rev. B 89, 075423 (2014). [3] J.J. Mazo et al., Phys. Rev. Lett. 118, 246101 (2017). [4] E. Gnecco et al., New J. Phys. 17, 032001 (2015).