Intracenter optical transitions in Mn2+ ion in CdMnTe crystals: the effect of strong Jahn-Teller coupling in excited state

Intracenter resonance optical transitions between ground and first excited states of a Mn2+ ion in bulk CdMnTe crystal are theoretically and numerically studied. An algorithm is proposed to calculate the matrix elements of the optical transitions under the influence of electromagnetic waves of different polarizations from a six-fold degenerate ground state 6A1 to a twelve-fold degenerate first excited state 4T1. The calculations were carried out with the account of a strong Jahn-Teller effect, which is due to the interaction of charge carriers in the excited state of the ion with local tetragonal distortions of the CdMnTe crystal lattice. By comparison with previously obtained experimental data, it is shown that polarization properties of the photoluminescence of manganese ions in such crystals as well as its spectral features could be explained only with the account of strong Jahn-Teller coupling in the excited state. The same calculation technique based on symmetry group analysis combined with numerical methods could be applied to intracenter Mn-transitions in other II-VI materials and it could be extended to other optically addressed atoms with highly degenerate electronic states coupled to vibrational modes.