Fluctuation-induced order in two-dimensional colloidal clusters
Department of Physics, University of Konstanz -
D-78457 Konstanz, Germany
Accepted: 21 August 2002
The behavior of a finite number (N = 29) of paramagnetic colloidal particles in 2D circular hard-wall cavities is investigated. By applying a magnetic field B, the interaction between the particles is varied. We demonstrate that the angular diffusion of the particles which are arranged in shells is highly anisotropic and shows a non-monotonic behavior as a function of B. When reducing radial particle fluctuations in one shell by a ring-shaped optical tweezer, the relative angular diffusion between adjacent shells increases again. This clearly demonstrates that radial particle fluctuations are responsible for an enhanced registration between adjacent shells.
PACS: 82.70.Dd – Colloids / 64.60.Cn – Order-disorder transformations; statistical mechanics of model systems / 83.10.Tv – Structural and phase changes
© EDP Sciences, 2002