Structures, optical properties and potentially electro-optical applications of magnetic fluid films

Under the action of externally-applied magnetic fields, a portion of magnetic particles was condensed out from the initially monodispersed magnetic fluid and formed into magnetic chains or columns, depending on the direction of the applied fields, These chains or columns evolved from a disordered phase to an ordered structural pattern as the field strength reached some critical value. It was further discovered that the optical properties, such as birefringence, transmission and magnetochromatics, were generated by the formation of the structures in the magnetic fluid films. With the tunability of the structural patterns by adjusting control parameters, the magnetic fluid films exhibited magnetically tunable optical properties. These phenomena bring up the promising feasibility of electro-optical devices, e.g. optical switch, filter, or grating by using homogeneous ferrofluid films.