Regensburg 2004 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 46: Poster
DY 46.88: Poster
Donnerstag, 11. März 2004, 16:00–18:00, Poster D
Phase transitions in periodic pinning arrays — •Konrad Mangold1, Michael Köppl1, Paul Leiderer1, and Clemens Bechinger2 — 1Universität Konstanz, Fachbereich Physik — 2Universität Stuttgart, 2.Physikalisches Institut
We study by means of videomicroscopy the phase behavior of two-dimensional (2D) paramagnetic colloidal systems on periodic pinning arrays, the latter being created by a hollographic optical tweezer technique. When the particle interacion is decreased by changing an external magnetic field the colloidal monolayer shows a melting transition from an incommensurable solid to a liquid phase. An undisturbed 2D system exhibits a two-stage melting as described by the KTHNY theory. With an additional pinning array the 2D system shows a rich phase behavior. The details of the diffusion of interstitial particles through a matrix of pinned particles depend among other things on the geometry of the pinning lattice (square or hexagonal) and on density ratio of pinned to diffusing particles. We compare our results with numerical studies on vortex melting in periodic pinning arrays.
We also present first results where the particle transport through a channel under non-equilibrium conditions is studied. A topological channel is created by means of electron lithography and the motion of the particles are studied for different particle interactions and channel geometries.