Abstract. Experimental data indicate that in the isostructural series the easy axis of the spontaneous magnetisation within the hexagonal plane alternates with the sign of the third Stevens factor. This confirms that the magnetocrystalline anisotropy of the rare-earth ions in the RCo₅ and R₂Co₁₇ intermetallics has a single-ion origin. It is clearly shown that Co positive charges play the dominant role in the creation of the crystal electric field in the 4f Co-rich compounds. The basal-plane anisotropy of Tb, Dy and Ho has also been examined. The point-charge model calculation gives good agreement with the experimental data for trivalent ions, especially for Dy and Ho. The large contribution of conduction electrons to the CEF has been evaluated by analysis of the available experimental data for RCo₅ and R₂Co₁₇.

Print publication: Issue 1 (January 1987)