The anisotropy of Gd–Fe exchange interaction for Gd 2 Fe 17 and Gd 2 Fe 17 H 3

The magnetization curves along the crystal axes for Gd2Fe17 and Gd2Fe17H3 were analysed based on the single-ion model. If the Gd-Fe exchange interaction has been taken as isotropic as usual, the fitted values of magneto-crystalline anisotropy of the Fe sublattices in Gd2Fe17 and Gd2Fe17H3 would become unreasonably different from those of the corresponding Y or Lu compounds. It was shown that the large difference is caused by the neglect of the anisotropy of the Gd-Fe exchange interaction.