Effect of Ga substitution on the Sm sublattice anisotropy in Sm2Fe17-xGax (0 <= x <= 8)

In order to study the unique behavior of the Sm sublattice anisotropy, magnetization curves along both the easy and hard directions were obtained at 10 K for Sm2Fe17−xGax (0⩽x⩽8) powders which were aligned using either static- or dynamic-field alignment methods. The Fe sublattice contribution was isolated by making similar measurements on Y2Fe17−xGax (0⩽x⩽8), as the presence of Y eliminates the rare-earth sublattice contribution. The results show that the Sm sublattice anisotropy is dominant for x⩾1. It increases with increasing Ga content, reaching a (broad) maximum of 1.8×107 erg/cm3 for x≈2–3, and then decreases and becomes negative for x≈5.5. This work shows that the unique behavior of the magneto-crystalline anisotropy for Sm2Fe17−xGax arises from the variation of the Sm-sublattice contribution with Ga substitution.