Concentration and the temperature dependence of the in-plane uniaxial anisotropy in amorphous CoZrDy thin films

Amorphous transition metal-rare-earth thin films of composition (Co_0.95Zr_0.05)_100-x(Dy)_x were prepared by RF sputtering. During deposition a DC magnetic field of 700 Oe was applied parallel to the film plane, so the films exhibit a very well defined in-plane uniaxial anisotropy K_u. The variations of K_u were investigated as a function of Dy content for the concentration range 9⩽x⩽26 and in the temperature range 4 K<T<300 K. The experimental data were analyzed by considering the possible contributions of pair ordering and/or of the single ion anisotropy to K_u. It is shown that the experimental data can not be explained if one suppose that K_u is essentially connected with a dipolar anisotropy. The overall result can be well explained, and the experimental curves web fitted by as calculated curves based on a mean field analysis, if one assumes that the dominant mechanism arises from single-ion anisotropy