Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 21: Quasicrystals

MM 21.5: Vortrag

Dienstag, 26. Februar 2008, 12:45–13:00, H 0111

Phase behavior of colloidal particles on a 2D quasicrystalline substrate — •Michael Schmiedeberg and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin, Germany

By using Monte-Carlo simulations, we study charged-stabilized colloidal particles in a two-dimensional decagonal potential and calculate their phase diagram as a function of the particle density and the strength of the substrate potential, which in experiments is realized by interfering laser beams.

As one expects, we find a triangular to liquid phase transition for small laser intensities and a ten-fold symmetric quasicrystalline phase for high potential strengths. For intermediate intensities, however, where the colloidal ordering is influenced by both the colloidal interaction and the substrate potential, we identify a series of interesting phases: For systems with low densities, where the number of colloidal particles is less than the number of potential minima, there is a quasicrystalline phase which exhibits bond orientations in 20 different directions. When the number of colloids exceeds the occurence of minima, we usually find a solid phase without any bond-orientational order. However, for certain densities the system locks into a highly ordered phase that is close to an Archimedean tiling.