Theoretical studies of the g factors and hyperfine structure constants for Ni + in AgGaS 2 and AgGaSe 2 crystals

Abstract

In this paper, the high-order perturbation formulas based on the two spin–orbit coupling parameter model for the EPR g factors g ∥, g ⊥ and hyperfine structure constants A ∥, A ⊥ of 3d 9 ion in tetragonal tetrahedral crystals are established by a molecular orbital approach. In these formulas, the contributions to EPR parameters from both the spin–orbit coupling parameter of central 3d 9 ion and that of ligands are included. By use of these formulas, the EPR parameters Δg ∥(=g s −g ∥), Δg ⊥(=g s −g ⊥) , A ∥ and A ⊥ for Ni + in AgGaS 2 and AgGaSe 2 crystals are calculated. The calculated results show good agreement with the observed values. The importance of the contribution from the spin–orbit coupling of ligands to various EPR parameters is discussed.