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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.66: Poster

Donnerstag, 30. März 2006, 16:00–18:00, P1

Ordering of a 2D colloidal system in a 1D quasicrystalline potential — •Michael Schmiedeberg and Holger Stark — Universität Konstanz, Fachbereich Physik, D-78457 Konstanz

Using the Landau-Alexander-McTague theory, Das and Krishnamurthy proposed that quasicrystalline order can be induced in a two-dimensional charge-stabilized colloidal system by a one-dimensional optical lattice consisting of modulations with wave vectors q₀τ and q₀/τ. Here, τ is the number of the golden mean and q₀ is the position of the first peak in the direct correlation function of the colloidal system in the liquid phase [1]. Our Monte Carlo simulations, however, demonstrate that such a stable two-dimensional quasicrystalline ordering of the colloids does not exist. We only find stable solid phases of trigonal and rhombic symmetry. Using a more careful implementation of the Landau-Alexander-McTague theory, we calculate a complete phase diagram consistent with the results of our simulations. The system also exhibits a new mechanism of laser-induced melting that relaxes strain in the rhombic phase induced by the optical lattice. Therefore, we find laser-induced melting for all temperatures in contrast to the same phenomenon governed by fluctuations [2].

[1] C. Das and H.R. Krishnamurthy, Phys. Rev. B 58, R5889 (1998)

[2] L. Radzihovsky, E. Frey, D.R. Nelson, Phys. Rev. E 63, 031503 (2001)