On the crystal-field-induced magnetic anisotropy in B-substituted RCo5compounds

Abstract

The ¹⁵⁵Gd Mossbauer effect and the magnetic properties were measured in the compounds GdCo₄B, Gd₃Co₁₁B₄, Gd₂Co₇B₃ and GdCo₃B₂. The crystal structures of all these compounds are related and can be thought to be built up by an ordered substitution of B atoms into the Co sites in GdCo₅. The observation of distinct types of quadrupole interactions at the various crystallographic nonequivalent Gd sites in these compounds allowed a semiempirical determination of a unique set of effective point charges which makes it possible to describe crystal-field effects in these materials in a satisfactory way. This set of semi-empirical point charges was successfully applied to analyse crystal-field effects in ternary rare-earth compounds of the type R₂Fe₁₄B and R₂Co₁₄B. In the RCo₅-based materials it is shown that increasing B substitution entails an increase in the second-order crystal-field parameter, which explains the increase in magnetocrystalline anisotropy.