Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 11: Topical Session Glass Dynamics IV

MM 11.1: Topical Talk

Montag, 22. März 2010, 16:00–16:30, H16

Slow transport in densely packed random environments — •Thomas Franosch — Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 München, Germany — Institut für Theoretische Physik I, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany

Conventionally the dynamics close to the glass transition slowes down uniformly, deviations being often referred to as violations of the Stokes-Einstein relation. In strongly size disparate mixtures the violations may even include that only one component freezes whereas the other exhibits long-range transport often accompanied by subdiffusive motion. A minimal model explaining the observed anomalous transport is the Lorentz model where a single tracer particle meanders through a frozen array of randomly distributed obstacles. As the packing fraction of the obstacles is increased, the motion is more and more confined to narrow channels of void space accompanied with a drastic reduction of the diffusion coefficient. Contrary to the standard glass transition scenario this suppression of motion is connected to a divergent length scale characterizing the underlying geometric percolation transition of the void space. Relying on extensive computer simulation, we explain the emergence of anomalous transport, the divergence of the non-gaussian parameter, and elucidate the role of correlations in the obstacle distribution.