INDUCED AND LOCAL ANISOTROPIES IN AMORPHOUS COZR RARE-EARTH THIN-FILMS CONTAINING PR, ND, AND TB

The induced in-plane and local magnetic anisotropies of rf sputtered ( Co93Zr7)(100-x)RE(x) thin films were investigated as a function of RE content for RE=Pr, Nd, and Tb by transverse biased initial susceptibil ity measurements at both film/air and glass/film interfaces. The depos ition was performed in a magnetic field. The films exhibit a very well defined in-plane anisotropy with negligible long-range fluctuations a nd a small coercive field H-c, in accordance with the experimental dat a. The overall variations of the transverse susceptibility are related to the ripple. The variations of the local anisotropy with compositio n were measured. Both the induced anisotropy K-u and the local anisotr opy K-loc increase with the increasing amount of RE in the layers. A c lear relationship between K-u and K-loc could be established. The resu lts are discussed in terms of the single-ion anisotropy of the rare ea rth. While the value of K-u is the same at both interfaces, the ripple constants were found to be slightly different. This last result is be lieved to be related to some local defects, the origin of which is als o suggested. Also the coercive force is discussed and explained in ter ms of a theoretical model. (C) 1996 American Institute of Physics.