Remarkable Magnetic Properties of Co-doped ZnO Nanorods Array at Room Temperature Originated from Vertical Growth on Zn Foil

Large-area arrays of highly oriented Co-doped ZnO nanorods with hexagonal structure were grown on Zn substrates by single-step hydrothermal process. Structure analysis indicates that the as-prepared products have wurtzite structure, and no other secondary phase is found in the nanorods. The intensity of UV emission peak decreases with the increase of Co doping concentration. When Co is doped into ZnO lattice, oxygen vacancies and Zn interstitials are created. The concentration of these defects increases with rise of the Co concentration. Magnetic measurement reveals that the Co doped ZnO nanorod arrays exhibit obvious room-temperature ferromagnetic behavior with a large coercive field Hc of 52.8 kA/m, which makes them potentially useful as building components for spintronics.