Study on magnetic and optical properties of porous anodic alumina/Co composite films with rainbow structural color prepared by an annular carbon electrode

Porous anodic alumina (PAA)/Co nanowires composite thin films of rainbow ring structural color with high saturation have been successfully fabricated using a one-step AC electrodeposition method. PAA thin films were used as a template and an annular carbon electrode as the counter electrode for preparation of the composite films. The results show that the length of Co nanowires decreased gradually from the center of the thin film along the radial direction, where the nanowires reflected light from the Al layer to improve the saturation of structural color. Although the magnetic performance of PAA/Co composite thin films decreased gradually along the radial direction, optical and magnetic properties of the PAA/Co composite films were effectively controlled by adjusting the oxidation time and electrodeposition voltage and time. The distribution of current density on the surface of PAA thin film was also studied using an annular carbon electrode to acquire a rule for changes in the quantity of Co nanowires in accordance with the deposition parameters.