材料期刊网

The spin Hamiltonian parameters (g factors and the hyperfine structure constants) for the cubic Mn(2+) centers in ZnX (X = S, Se, Te) and CdTe are investigated theoretically using the perturbation formulas of these parameters for a tetrahedral 3d(5) cluster containing both the crystal-field and charge-transfer contributions. The relevant molecular orbital coefficients are uniformly determined from the cluster approach, and the calculated spin Hamiltonian parameters are in good agreement with the observed values. The g-shifts of the g factors related to the pure spin value g(s) (approximate to 2.0023) arising from the charge transfer contributions are opposite (positive) in sign and much larger in magnitude than those from the crystal field contributions. On the other hand, the contributions from the charge-transfer mechanism to the hyperfine structure constants are the same in sign and about 20%-30% in magnitude of those from the crystal-field mechanism. The importance of the charge transfer contributions increases significantly with the increase of the covalency and the spin-orbit coupling coefficient of the ligand, i.e., S(2-) < Se(2-) < Te(2-).