2005 Volume 5 Issue 1 Pages 22-34
A variety of additives and underlayers were examined to obtain good soft magnetic properties for Fe-Co system films with a high saturation magnetic flux density (Bs) of the 2.4 T class. It was found that Al2O3 is an excellent material for use as an additive. The continuous columnar structure of the film is formed by Al2O3 segregated in the grain boundaries from the initial growth layer up to the top layer. The lattice spacing of Fe-Co films was expanded by Al2O3 addition. The small grains in the initial growth and the random crystal orientation due to the presence of an underlayer are also important factors in obtaining good soft magnetic properties for Fe-Co system films. An Hch (Hc in the hard axis direction) value of less than 1 Oe was obtained only by using a combination of Al2O3 addition and an fcc structure underlayer film in a wide range of film thicknesses. The mechanism whereby soft magnetic properties are obtained in Fe-Co system films seems to be partially explained by the combination of Hoffman's ripple theory and the exchange-induced ripple reduction process.
