Temperature Dependence of the Anisotropy Constants of Gd, Tb, and Dy

The sources of magnetocrystalline anisotropy have been studied for the ferromagnetic rare earth metals Gd, Tb, and Dy. In the weak anisotropy case of Gd the contributions to the anisotropy constants from the crystal field have been calculated by spin-wave theory treating the crystal-field terms as a perturbation. Estimates have also been made of the contributions to K1(T) from real and pseudo-dipole-dipole interactions and from the …