Controlled Directionality of Ellipsoids in Monolayer and Multilayer Colloidal Crystals

We present a self-assembly approach for monolayer and multilayer deposition of ellipsoids with a controllable direction. The direction of the ellipsoids in the assembly can be conveniently tuned by external applied magnetic field. This level of control on positional and directional order suggests a way to build monolayer templates for lithography with two-dimensional patterns and three-dimensional anisotropic photonic crystals, which may open the Way toward the complete photonic band gap in the visible.