8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.16Wed 711:10-14:00Driven colloidal monolayers on periodic andquasiperiodic substrate potentials as model systems fornanotribologyThomas Bohlein, 1 Jules Mikhael, 1 and Clemens Bechinger 11 Physiklisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart,GermanyWe experimentally study the sliding behavior of a two dimensional colloidal crystal interactingwith periodic and quasiperiodic light induced substrate potentials created by overlapping severallaser beams. Lateral forces are imposed onto the monolayer by the continuous translation of thesample cell which leads to Stokes forces acting on each particle. In agreement with atomic forceexperiments, we observe high friction for periodic commensurate systems. In contrast, for periodicincommensurate and quasiperiodic systems the static friction force almost vanishes, giving rise toa superlubric sliding state. Our results are in agreement with theoretical predictions that a lowfriction coefficient can be related to dynamical defects such as kinks and antikinks which providea rather effective mechanism for efficient sliding of interfaces. Additionally, we examine the effectof phononic and phasonic excitations of the quasiperiodic substrate potential on the sliding friction.16