Dresden 2014 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 41: Poster - Pattern/ Nonlinear Dyn./ Fluids/ Granular/ Critical Phen.
DY 41.22: Poster
Donnerstag, 3. April 2014, 17:00–19:00, P3
Fluctuations of orientational order and clustering in a two-dimensional colloidal system under quenched disorder — •Tobias Horn1, Sven Deutschländer2, Hartmut Löwen1, Georg Maret2, and Peter Keim2 — 1Institut für Theoretische Physik II: Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany — 2Fachbereich für Physik, Universität Konstanz, D-78464 Konstanz, Germany
Using both, video-microscopy of superparamagnetic colloidal particles confined in two dimensions and computer simulations of repulsive parallel dipoles, we study the formation of fluctuating orientational clusters and topological defects with respect to the KTHNY-like melting scenario under quenched disorder. We analyze cluster densities, average cluster sizes, the population of non-cluster particles as well as the development of defects as a function of system temperature and disorder strength. In addition, a probability distribution of clustering and orientational order is presented. We find that the well known disorder-induced widening of the hexatic phase can be traced back to the distinct characteristics of clustering and defect formation along the melting transitions from the solid phase via the hexatic phase to the isotropic fluid.