Single crystal magnetization of ErAl₂and interpretation in terms of the crystalline field

Measurements are reported of the magnetization of single crystals of ErAl 2 between 4.2K and 16K for magnetic fields up to 150 kOe applied along the (111), (110) and (100) directions. The results are interpreted in terms of the crystal field using a two-dimensional molecular-field approach. Within this microscopic description of the magnetization and the related magnetocrystalline anisotropy the authors use only two temperature-independent crystal field parameters and the Curie temperature. A least-square fitting procedure gives B 4 =1.10*10 -4 meV, B 6 =-1.34*10 -6 meV and T c =14K. With these parameters they obtain good agreement between calculated and measured magnetization curves.