Magnetic anisotropy of the Y(Co1-xFex)3 pseudobinary compounds

The anisotropy energy of the Y(Co_{1 - x}Fe_x)₃ compounds has been determined between 4.2 and 250 K. The concentration dependence of the anisotropy energy behaves anomalously in this pseudo-binary series. Upon increasing the iron content, the anisotropy energy increases up to x = 0.25, then decreases, changes sign around x = 0.45 and reaches a flat minimum at the iron-rich side. This anomaly can satisfactorily be explained in terms of the individual site anisotropy model by considering the different occupancy factors of iron and cobalt for the 3d sites.