Electrically switchable colloidal ordering in confined geometries

A novel field-induced approach has been developed that allows the controlle d ordering of colloidal particles in confined systems. In this approach, an electric field is used to create a strong lateral dipole-dipole interactio n that induces colloidal crystallization in two-dimensional geometries. Bec ause the particle density is relatively low and the interaction of long ran ge, colloidal mobility is high enough to allow rapid crystallization upon t he application of the electric field. The observed phase transitions are fu lly reversible and can be readily controlled by adjusting either the applie d field strength or particle confinement.