We investigated the effect of bias sputtering on the oxidation resistance of amorphous Tb32Fe68compositionally modulated films (CMFs). The columnar morphologies of aged, unbiased films were more diffused than those of ashyphen;deposited films. On the other hand, the morphologies of the minus;70 V bias sputtered, aged film were as dense and featureless as those of ashyphen;deposited films. The substrate bias also influenced the magnetic and magnetohyphen;optical characteristics of aged films. The Kerr rotation obtained from the film surface was significantly increased by the formation of a transparent, nonmagnetic oxide layer, and by optical interference between this layer and the unoxidized amorphous matrix. The coercivity of the amorphous matrix in unbiased films increased markedly with aging time. These changes are attributed to compositional changes enhanced by the easy diffusion path of oxygen in the columnar void structure. In contrast, the coercivity of minus;70 V bias sputtered films was unchanged with aging, and exhibited theBhyphen;Hloops of exchange coupled double layers. The results indicated that the intrinsic stability of Tbhyphen;Fe CMFs was strongly influenced by the film microstructure and was improved by the application of substrate bias during deposition.
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