Magnetic Anisotropy of Gd-R-Co (R = Tb,Dy,Ho,Er) Thin Films

The effects of adding a third element (Tb, Dy, Ho, or Er) to the magnetic anisotropy constant Ku of amorphous Gd-Co thin film, are reported. The Ku values of samples, formed by RF sputtering with a DC bias, were calculated from measurements of K¿, and compositions determined by X-ray spectroscopy. As in Gd-Co film, a positive Ku results in Gd-R-Co when the bias voltage Vb is raised. Ku increased when Tb, Dy and Ho were added, but decreased on adding Er. The order of increase of Ku corresponded to the relative anisotropic energies per R ion, and the contribution of the R element to Ku is thought to depend on the shape of the 4f electron shell of the R element.