Explanation of the g-factors and Hyperfine Structure Constants of Co²⁺ in Tetragonal K₂ZnF₄

Abstract

The formulas of the ^-factors g n , g ± and the hyperfine structure constants A,,.for 3d 7 ions in tetragonal octahedral crystals are established from a cluster approach. Differing from previous formulas, in these formulas the role of configuration interaction (CI)-and covalency (CO)-effects is considered, and the parameters related to both effects are obtained from the optical spectra and the structural parameters of the studied crystal. From these formulas, the EPR parameters g, and A t for K 2 ZnF 4 :Co 2+ are calculated. The results show good agreement with the observed values. The contributions to the EPR parameters gi and 4, from the CI and CO effects, and the relationship between the sign of Ag {=g ± -g n ) and the tetragonal distortion (elongated or compressed) of the ligand octahedron are discussed.