A ligand-field approach to the zero-field splitting of 3d⁵(S=⁵/₂) ions: Fe³⁺and Mn²⁺paramagnetic centres in garnets and other oxides

Abstract

The zero-field splitting (ZFS) of Fe3+ and Mn2+ paramagnetic centres in a series of isomorphic oxides (garnets) is investigated on the basis of a ligand-field approach. A semi-empirical method is used in order to estimate the variations in the ligand-field parameters from site to site. The model leads to a satisfactory reproduction of the experimental data. Moreover, the theoretical predictions about the sign of the ZFS in different oxides are also in agreement with the experiment, and the ligand-field approach is able to explain the failure of other models in reproducing these signs.