Study of the iron contribution to the 3d-sublattice anisotropy in some uniaxial YCoFe structures derived from the CaCu5 unit cell

The effects of the Fe substitution for Co on the anisotropy of uniaxial structures (YCo3, Y2Co7, Y5Co19, YCo5) all derived from the parent CaCu5 unit cell were studied. The unique Singular Point Detection (SPD) technique was used to measure temperature and composition dependence of the anisotropy. A characteristic behaviour of both Co and Fe anisotropies was individuated. The overall Fe sublattice anisotropy is always opposite and 2–3 times larger than that of Co. From the temperature behaviour of the anisotropy constant (K1), spin reorientation transitions (SRT) were predicted at temperature values which depend on Fe content. ac susceptibility measurements seem to confirm the presence of SRT. The magnetic phase diagrams of mixed Y-Co-Fe compounds were derived