Anisotropic diffusion of islands and topological defects in dipolar chains of islands in freely-suspended SmC liquid crystal films*

Islands, disk-like inclusions of extra layers in few-layer thick, freely-suspended tilted smectic liquid crystal films, stabilize +2π chiral vortices in the two-dimensional XY field giving the azimuthal orientation of the local molecular tilt. We have studied the Brownian motion of islands and their companion - 1 defects on the background film in a dipolar chain of islands. The mean square fluctuations of the position are strongly anisotropic, the island mobility parallel to the chain direction being up to four times smaller than their mobility perpendicular to the chain. Measurements of thermal fluctuations of islands and topological defects in dipole chains will be compared with theoretical predictions.