Crystallographic and magnetic investigations of the cobalt columns electrodeposited in the pores of anodic alumina

Textured polycrystalline cobalt columns are electrochemically deposited in the pores of anodic alumina layers of 15 mu m thickness. X-ray diffraction investigations show that the cobalt columns are polycrystalline and textured. The crystallite size of the cobalt columns is about 80 nm and the c axis is oriented at an angle of about 60 degrees towards the layer surface. The layers show perpendicular magnetization anisotropy. Anomalies in the magnetization parameters such as saturation magnetization, coercivity and the area of the magnetization hysteresis loop around an angle of 40 degrees are also observed. Maximum coercivity of 1.40 kO(c) and a M(r)/M(s) ratio of 0.714 are observed for the mechanically polished AlMg1 substrate before anodic oxidation. The crystallographic and magnetic data further suggest a possibility that perpendicular magnetic anisotropy of the layers is caused by the cobalt columns perpendicular to the layer surface rather than c-axis orientation of polycrystalline cobalt columns.