Soft magnetic properties and structure of high B/sub s/ Fe-Co-Al-O films

Fe-Co based films have been investigated for writing head core materials with a high B/sub s/ in recent years. We have reported that the combination of a small amount of Al/sub 2/O/sub 3/ addition and a soft magnetic underlayer film is important to obtain small H/sub ch/ with high B/sub s/ of 2.4 T in a wide range of film thickness for Fe-Co films. The mechanism of soft magnetic properties by using the Al/sub 2/O/sub 3/ addition and/or the soft magnetic underlayer film is studied. We confirm that the soft magnetic properties of Fe-Co system films are related to the expansion of the lattice constant and random crystal orientation.