Anodic oxide films of aluminum, containing ferromagnetic particles electrodeposited in their pores (magnetic composite alumina films) have high perpendicular magnetic anisotropy, making these films suitable for use in hard disks and other magnetic recording media. This study was undertaken to obtain these films with magnetically harder characteristics. By controlling the anodizing conditions, pore widening process and electrodeposition of iron particles, it was possible to obtain films having a coersive force He of greater than 2000oe, a magnetic energy product (BH) max of greater than 0.2MG·Oe, and thickness of 20∼100μm. These films were formed on the sides of rotary drums and were given multipolar magnetization making them applicable for high-precision magnetic rotary encoders.
