The field induced magnetic anisotropy in amorphous Co-RE alloys films

The properties of the coherent anisotropy, formed by applying a magnetic field in the film plane during deposition, were studied in amorphous (Co/sub 1-y/Zr/sub y/)(RE)/sub x/ thin films, for various RE and deposition parameters. When RE=Pr,Nd,Dy and Tb an in-plane uniaxial anisotropy K/sub u/ is developed. The variations of K/sub u/ versus x, RE and measuring temperature are well explained by a single-ion anisotropy mechanism. The change of K/sub u/ with P/sub Ar/ and deposition temperature T was studied on Co/sub 95-x/Zr/sub 5/Dy/sub x/ films and for 522 films with isotropic magnetic properties are obtained at T/sub d/ higher than T/sub crit/=f(x). Structural investigations show that K/sub u/ is related to sites containing CoDy pairs. The data are explained by a model based on the bond orientational mechanism: In samples prepared at low T/sub d/, K/sub u/ is related to the individual deformations of sites, while when thermal fluctuations are important, directional correlations of the sites are formed. The peculiar results observed for RE=Sm and Gd are due to the intrinsic properties of these RE.<>