A theory of the magnetic anisotropy of rare earth‐iron compounds

An expression for the magnetic anisotropy energy of a model of the ternary compounds RxR′1−xFe2 is derived. The fourth and sixth‐order crystal field energies are treated as a perturbation on the rare earth‐iron exchange. Using this expression, it is shown that, for certain ranges of x, the colinear phases are unstable to the formation of spin‐canted phases in which the net magnetization points along nonmajor symmetry directions. DyxTb1−xFe2 is discussed as an example.