Design of alumina composite films with gradual structural color and magnetism using non-uniform electric field

Abstract Co@ alumina composite film with multicolor structural color was prepared following an alternating current electrodeposition method under a non-uniform electric field. After the electric field was established by adjusting the angle between electrodes, metal Co was deposited into the nanopores of alumina film. The results of theoretical calculations and numerical simulations show that the deposition current density on the surface of the composite film presents an arc distribution under the non-uniform deposition electric field. In addition, the microstructure of the film exhibited a gradient change along the radial direction, showing gradual structural color and magnetism. The experimental results further suggest that under a non-uniform electric field, the ability to fine-tune the microstructure and physical properties of the alumina composite film can be achieved by adjusting the angle between electrodes, thickness of the porous alumina layer, and deposition time.