Practical FeCo Films for Perpendicular Writer Pole

An attempt is made in this publication to review various developments of FeCo films for recording heads in the last decade and to look at emerging developments regarding these films. A series of FeCo films from 100% Fe to 100% Co was sputter deposited, characterized, and analyzed for various magnetic properties such as magnetostriction, uniaxial anisotropy, coercivity, dispersion, and saturation magnetization. Many process parameters, with the most influencing parameter being sputter pressure, play an important role especially influencing dispersion and/or hard axis coercivity (H_ch) in these materials. Out of the many developments to date the effect of seed layer(s) in reducing grain size of high moment bcc FeCo films is still intriguing and, hence, a comprehensive review and analysis of seed layer effects are included. Although film stress can play an important role in optimizing H_ch, there is no clear trend seen between film stress and H_ch when viewed across broad processing conditions. Higher H_k evolution with oblique deposition is an interesting phenomenon in these films. Uniaxial anisotropies of nearly 1000 Oe were found. The anisotropy evolution is explained through magnetoelastic energy and through crystal structure. Even though these films are very columnar in nature it was found that there was little to no fiber texture present in these films and there was no difference in texture between fine grained and coarse grained FeCo films.