Magnetic Anisotropy of Co Thin Films Prepared by Oblique Incidence

To investigate exchange interactions between metallic cobalt and CoO, the authors formed cobalt thin films oxidized to varying degrees, by oblique (65°) evaporation onto polyimide films, and studied the magnetic and other properties as functions of x = (metallic cobalt mass)/(total cobalt mass). The coercivity increased with x in all cases, and the temperature dependence of the uniaxial anisotropy constant Ku was similar for all but the most heavily oxidized sample, which also showed a maximum in rotational hysteresis loss WRH at 280 K. At the Neél point of CoO is 293 K, considerable amounts of CoO are thought to be present in the film, interacting with matallic Co.