Effects of CoTi-doping on longitudinal barium ferrite thin film media

It is shown that the coercivity of barium ferrite thin film media can be adjusted over a very wide range from 1000 Oe to 4000 Oe by the proper amount of CoTi-doping. The coercivity decreases dramatically with increasing CoTi concentrations in the film, while the saturation magnetization decreases only slightly. The optimized S_q, S* and SFD values are relatively unaffected by CoTi-doping. The grain size decreases as the amount of CoTi-doping increases. A multilayer structure consisting of alternating pure barium ferrite and CoTi-doped barium ferrite layers has been demonstrated to be useful for controlling the overall film composition through a diffusion process. The direct correspondence between the coercivity and the composition provides a guideline for the practical use of this material