Aligned ZnO:Co nanorod arrays: Electrophoretic deposition fabrication and magnetic manipulation

ZnO:Co thin films with various morphologies were synthesized via two-step electrophoretic deposition at controlled conditions. Their morphologies, structures, and magnetic properties were systemically investigated. Dense solid, granulated, and nanorod-array morphological films can be obtained by carefully tuning the deposition conditions. The structural results indicate that Co doped into the ZnO lattice occupy the Zn²⁺ ion sites in a high-spin Co²⁺ state. Magnetic observations show that all the films have room-temperature ferromagnetisms but their magnetisms are different because of their different morphologies and structures. The magnetism of the nanorod-array film is considerably higher than those of the granulated and solid films, which indicate that the magnetic properties of ZnO:Co films can be manipulated by tuning their morphologies and structures. The mechanism of electrophoretic deposition and magnetism differences of the films are discussed in detail. These ferromagnetic semiconductor films with controllable morphologies and structures are expected to present extensive applications in the future.