Magnetization process in RE-TM alloys: Wall mobility and nucleation

Magnetization process on GdFe and TbGdFe samples is studied. It is seen that reverse domains nucleation and domain wall motion are thermally activated phenomena. As a result new expressions for coercivity based on thermal activation are proposed. If the magnetization process occurs mainly by nucleation, it is suggested that coercivity is only a function of temperature, saturation magnetization, uniaxial anisotropy and Curie temperature. Predicted values of the coercivity are compared with experiments and available data as found in the literature.