Session D40 - Poster Session I.
POSTER session, Monday afternoon, March 12
Exhibit Hall, Washington State Convention Center
A model system for studying the effects of quenched disorder on the properties of a two-dimensional elastic system is introduced. The system is a mono-layer colloidal crystal of charged polystyrene micro-spheres confined between two silica plates. One of the plates is prepared with the appropriate amount of roughness to act as a random, un-correlated pinning potential, whose strength is controlled by the separation of the two plates. At weak disorder we observe formation of ordered regions up to a few hundred lattice constants, with a low density of dislocations. At increasing disorder, we observe a transition to a disordered, glassy phase. Upon application of an electric field, the system can be set into motion. Different regimes are observed as a function of disorder and driving force, ranging from plastic flow, constrained into fluid channels around pinned regions, to elastic, were the whole crystal is sliding uniformly, without tearing.