Dresden 2003 – scientific programme

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.11: Poster

Thursday, March 27, 2003, 15:30–18:00, P1

Commensurate-incommensurate phase transitions of colloidal monolayers in periodic pinning arrays — •Konrad Mangold, Juliane Birk, Paul Leiderer, and Clemens Bechinger — Universität Konstanz, Fachbereich Physik, 78457 Konstanz

We study the phase behavior of two-dimensional paramagnetic colloidal systems on square pinning arrays, the latter being created by a holographic optical tweezer technique. When the particle interaction strength is decreased a transition from an incommensurate to a commensurate solid is observed. At even smaller pair-potentials, the interstitial particles start to melt whereas the particles at the substrate pinning sites are still localized. Our results are in good agreement with recent numerical studies on vortex melting in periodic pinning arrays.

In an other experiment we investigate the melting behavior of a binary suspension of small (2.7 µ m) and large (4.5 µ m diameter) paramagnetic particles in a circular cavity. We observe a sequence of phase transitions where first the large and then the small particles form an ordered structure.