Spin‐reorientation phenomenon in pseudobinary (Pr1−xRx)Co5 compounds (R=Sm, Gd, Dy, Tb, Ho, and Er) as determined by ac susceptibility measurements

Spin‐reorientation transitions in (Pr1−xRx)Co5+δ, where R=Sm, Gd, Tb, Dy, Ho, and Er were determined by ac susceptibility measurements. The spin‐reorientation temperature TSR of PrCo5 decreases from 105 K to lower temperatures when Pr is partially replaced by Sm, Gd, or Er. This decrease arises from different causes: the decrease of TSR in (Pr1−xGdx)Co5 results from the dilution of nonaxial anisotropy on the Pr sublattice, while the decrease of TSR in (Pr1−xSmx)Co5 and (Pr1−xErx)Co5+δ is due to the positive second‐order Stevens coefficients of Sm and Er which yield uniaxial anisotropies. Rare earths of negative second‐order Stevens coefficients such as R=Tb and Dy give rise to axial to conical and conical to planar transitions for x≳0.3 and 0.4 in (Pr1−xTbx)Co5+0.1x and (Pr1−xDyx)Co5+0.2x, respectively. Magnetic anisotropy phase diagrams of these systems are constructed accordingly.