Abstract
Amorphous Fe100−XErX films, with 8<X<30 were prepared by RF sputtering and their magnetic properties studied. The saturation magnetization M0, the uniaxial anisotropy constant Ku and the coercive field Hc were studied as a function of the Er composition. The Er moment at 4.2 K found to be about 7μB revealed a “sperimagnetic” structure for the Er. The mean field theory has been used to explain the temperature and compositional dependencies of the magnetization of Fe100−XErX. This analysis yields the effective exchange interaction between Fe–Fe and Fe–Er atom pairs. Ku and Hc are related by the equation Hc=αKun/μ0MS with the fitting parameters α and n.