Regensburg 2010 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 10: Nonlinear Dynamics I

DY 10.5: Vortrag

Dienstag, 23. März 2010, 15:00–15:15, H46

Periodic orbits in the sliding of graphite flakes — •Astrid S. de Wijn, Claudio Fusco, and Annalisa Fasolino — Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands

Theoretical consideratons show that the sliding of an atomic layer weakly interacting with an incommensurate periodic substrate can occur with vanishingly low friction. Indeed, extremely low friction has been observed experimentally in several systems and this effect has been named superlubricity. However, there is recent evidence that the incommensurate superlubric state is destroyed by rotation of the sliding flake [2], leading to a commensurate state with high friction.

In this work, we study the dynamics of finite rigid graphite flakes on a graphite surface. In numerical simulations, we find that after an initial short period, the flake either rotates and locks into a commensurate orientation or it remains incommensurate and slides with extremely low friction. We construct a simple model system which captures the essential dynamics, and for which the stability can be investigate d analytically. We show that for a realistic system periodic orbits exist that correspond to the commensurate and incommensurate states and that they may be stable. We investigate the robustness of the incommensurate superlubric state against parameters such as sliding velocity and temperature.

[1] M. Dienwiebel et al., Phys. Rev. Lett. 92, 126101 (2006).

[2] A.E. Filippov et al., Phys. Rev. Lett. 100, 046102 (2008).