Annealing effects on structural and magnetic properties of Co-doped ZnO nanowires synthesized by an electrodeposition process

Arrays of Co-doped ZnO nanowires were fabricated by electrodeposition of Zn2+ and Co2+ into an anodic aluminum oxide template followed by post-oxidation annealing in an Ar/O2 mixed atmosphere. Transmission electron microscopy showed that the nanowires were uniform with a diameter of about 75 nm. Significant differences in the crystalline structures of samples annealed at different temperatures were observed. Magnetization measurements showed that the Co-doped ZnO nanowires exhibit room-temperature ferromagnetism that changed with the annealing temperature.

Research highlights▶ In this paper, arrays of Co-doped ZnO nanowires were firstly fabricated by electrodeposition of Zn2+ and Co2+ into an anodic aluminum oxide template followed by post-oxidation annealing in an Ar/O2 mixed atmosphere. Magnetization measurements showed that the Co-doped ZnO nanowires exhibit room-temperature ferromagnetism that changed with the annealing temperature. ▶ In the discussion segment, we discussed the influence of annealing on the crystalline structure and magnetic anisotropy of the nanowires. We think the improvement of coercivity and remanence of the samples may attributed to the competition between shape anisotropy and magnetocrystalline anisotropy caused by annealing treatment.