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

We report an experimental system based on rigid, monodisperse, microparticl es With tunable surface properties for the study of topological defects tha t form about dispersed solid phases in anisotropic media. We clearly observ e equatorial Saturn-ring defects to form a distance (0.09 +/- 0.01)R from t he surface of isolated microspheres (with strong homeotropic anchoring) dis persed in nematic phases. These defects, some of which are observed to be s table for up to a month, are similar in size to past theoretical prediction s (with strong homeotropic anchoring) and can be reversibly expanded in an electric field.