Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Poster: Colloids and Complex Liquids

CPP 20.15: Poster

Tuesday, March 12, 2013, 18:15–20:15, Poster C

Directional locking and dynamical ordering of fluid colloidal monolayers driven across quasiperiodic substrate potentials — •Thomas Bohlein, Christoph July, and Clemens Bechinger — 2. Physikalisches Institut, Universität Stuttgart, Germany

Particles driven across an ordered potential energy surface may either follow the direction of the driving force or become entrained along any of the commensurate directions of the substrate. Such directional locking effects are of great technological relevance since they allow sorting of particles according to their size or refractive index. Here we experimentally study the sliding behavior of a two dimensional disordered colloidal monolayer interacting with quasiperiodic light induced substrate potentials. When the direction of the driving is varied with respect to the substrate, we find directional locking at angles corresponding to the symmetry axes of the underlying potential. On the locking steps the colloids assemble into dynamically ordered structures which consist of periodically spaced bands. We show that such ordered colloidal phases can be understood within the framework of periodic average structures which stems from the structure determination of complex metal alloys.