1.Department of Physics,Civil Aviation Flight University of China,Guanghan,People’s Republic of China;2.Department of Material Science,Sichuan University,Chengdu,People’s Republic of China
Abstract:
The high-order perturbation formulas founded on the two-mechanism model are applied in this paper to compute the spin-Hamiltonian parameters (g factors g//, g⊥ and zero-field splitting D) of the trigonal Mn4+ centers in Y2Ti2O7:Mn4+ crystal. In this model, besides the contributions from the traditional crystal-field (CF) mechanism (in the CF theory) related to CF excited states, those from the charge-transfer (CT) mechanism connected with CT excited states are contained. The calculated results are reasonably coincident with the observed values. The calculations show that the contributions of CT mechanism to spin-Hamiltonian parameters (in particular, the g factors) for (MnO6)8? clusters are large and cannot be neglected. The defect structure of trigonal (MnO6)8? clusters in Y2Ti2O7:Mn4+ crystals is also evaluated. The results are discussed.