Interactions and dynamics of oil and ferromagnetic droplets on 2D Smectic Films*

Small droplets of paraffin oil, both neat and doped with barium hexaferrite (BF) colloidal particles, were deposited on the surface of freely suspended smectic films. Droplet chains are observed both on uniform films and along layer steps, with the droplet spacing depending on the frequency of an applied electric field. When doped with a very small amount of BF colloidal particles, the droplets also respond to applied magnetic fields, which induce translational motion, island formation, and changes in the size of the droplets. The aggregation and chaining behavior induced by an electric field are significantly altered by the presence of a magnetic field. The interactions between droplets and their dependence on the presence of electric and magnetic fields could be indicative of dipolar interactions between the droplets. We will present the behavior of collective systems of these isotropic oil and ferromagnetic inclusions on 2D films, including their equilibrium spatial organization and interactions, and their shape evolution as a function of applied electric and magnetic field in both smectic A and smectic C phase films