Synthesis of BiFeO3/ZnO core-shell hetero-structures using ZnO nanorod positive templates.

We report the synthesis, morphology, and magnetization characteristics of BiFeO(3) (BFO)-covered ZnO nanorod arrays (ZNAs). High quality and well-aligned ZNAs were grown by a hydrothermal method. BFO shells were deposited by sputtering at ambient temperature and then annealing in an oxygen atmosphere. The BFO shells crystallized to form a perovskite structure at 450 °C. Scanning electron microscopy and high resolution transmission electron microscopy demonstrated that the BFO shell was polycrystalline and randomly oriented, covering the ZnO nanorods well. The magnetization-magnetic field loops measured at 5 and 300 K indicate that the BFO/ZNA hetero-structure exhibits ferromagnetic order. The BFO/ZNA displays enhanced coercivity and saturated magnetization as compared with BFO thin films.