Jahn–Teller effect in 4T2g excited state of Mn2+:MgO

Abstract

The aim of this paper is the estimations the electron-vibrational interaction constants, Huang–Rhys factors and Jahn–Teller stabilization energy, in 4T2g excited state of divalent manganese, doped in magnesium oxide single crystal, using two methods of calculations.First method is based on the exchange charge model of crystal field and has been applied to determine the dependence of crystal field strength 10Dq on R distance between divalent manganese impurity ion and oxygen ligands, in octahedral site symmetry. Obtained results were extrapolated by the power law and was shown that 10Dq depends on R as 1/Rn, with n=5.785. This deviations from value n=5, predicted by the simple point charge model of crystal field, is explained by the covalent and exchange effects. The second method is based on Ham quenching of the spin–orbit splitting of 4T2g excited state, described by the effective second-order spin-Hamiltonian.The obtained values for electron-vibrational interaction constants, Huang–Rhys parameters and Jahn–Teller stabilization energy were compared between them and discussed. Comparison of the results with experimental data are quite satisfactory and confirm the reliability of exchange charge model and Ham reduction scheme for the title system.