Observation of saturn-ring defects around solid microspheres in nematic liquid crystals.

We report an experimental system based on rigid, monodisperse, microparticles with tunable surface properties for the study of topological defects that form about dispersed solid phases in anisotropic media. We clearly observe equatorial Saturn-ring defects to form a distance (0.09+/-0.01)R from the surface of isolated microspheres (with strong homeotropic anchoring) dispersed in nematic phases. These defects, some of which are observed to be stable for up to a month, are similar in size to past theoretical predictions (with strong homeotropic anchoring) and can be reversibly expanded in an electric field.