Dynamic Superlubricity in Microscale Graphite
Friday, 04 Dec. 2015, 13:00 - 14:00
Presenter: Jiarui Yang; Tsinghua University, China
Host: M. Aspelmeyer
Where: Schrödingerroom, 4th floor, Boltzmanng. 5, 1090 Wien
A sheared microscopic graphite mesa retracts spontaneously to minimize interfacial energy. Using an optical knife-edge technique, we report first measurements of the speeds of such self-retracting motion (SRM) from the mm/s range at room temperature to 25 m/s at 235 Celsius degree. This remarkably high speed is comparable with the upper theoretical limit for sliding interfaces exhibiting structural superlubricity. We observe a strong temperature dependence of SRM speed which is consistent with a thermally activated mechanism of translational motion that involves successive pinning and depinning events at interfacial defects. The activation energy for depinning is estimated to be 0.1–1 eV.