Theory of the ligand-correlated covalent effect on spin orbit coupling for Cr3+ ion doping in a variety of oxide crystals

By using the complete energy matrix and taking into account the contributions from the spin orbit coupling of the central ions as well as those of the ligand ions, the local structure distortion have been studied for Cr3+ ions doping in KAl(MoO4), Y3Ga5O12, Y3Al5O12 and ZnAl2O4 crystals. The results show that the local structure exhibit elongation distortions for the doped systems. Moreover, the influence of the local structure parameter θ on the EPR parameter D are studied. The relationships between D and (ζ, ζ′) as well as the average parameter ζ1 ( ζ 1 = ( ζ + ζ ′ ) / 2 ) and the different parameter ζ2 ( ζ 2 = ( ζ - ζ ′ ) / 2 ) are discussed.