Tunable negative-index photonic crystals using colloidal magnetic fluids*
Geng Tao†, Wang Xin, Wang Yan, Dong Xiang-Mei
       
Schematic diagram of the PC slab formed in a magnetic fluid under externally perpendicular magnetic field and confined by the substrate and superstratum along the direction of the magnetic field. a and h are the periods and heights of the magnetic columns, respectively.