Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 5: Soft matter

DY 5.7: Talk

Monday, March 23, 2009, 16:15–16:30, ZEU 255

Ordering of colloidal particles on quasicrystalline substrates with decagonal or tetradecagonal symmetry — •Michael Schmiedeberg and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, 10632 Berlin, Germany

Quasicrystals are non-periodic solids that nevertheless have a long-range positional order. They possess rotational point symmetries, such as five, eight, ten, or twelve-fold rotational axes that are not allowed in periodic crystals. However, not for all rotational symmetries stable quasicrystals exist in nature. For example, quasicrystals with seven-fold rotational axes have not been observed so far.

By using Monte-Carlo simulations, we study charged-stabilized colloidal particles in two-dimensional decagonal or tetradecagonal potentials, which in experiments are realized by five or seven interfering laser beams, respectively. For intermediate light intensities and special particle densities, orderings corresponding to Archimedean-like tilings occur in both potentials. A closer analysis of these structures reveals substantial differences between the decagonal and the tetradecagonal potential. For example, there are large areas with almost periodic ordering in the tetradecagonal but not in the decagonal potential. We give a possible explanation of this behavior by analyzing properties of the substrate potential that depend on whether its rotational symmetry is realized in nature or has never been observed.