Magneto-optical study of CdS crystals doped with Mn

The effect of magnetic impurity atoms on the magneto-optical properties of CdS:Mn crystals is investigated. It is shown that the large circular absorption dichroism and gigantic Faraday rotation near the fundamental absorption edge, which are observed in the crystals, are due to splitting of the lowest exciton state (A-exciton). The splitting is caused by strong exchange interaction between the band electrons and electrons localized at the magnetic impurity atoms. The exchange integral for valence electrons obtained by comparing the splitting of A- and B-exciton states exceeds by more than five times the exchange integral for electrons of the conductivity band and is 5.6+-0.8 eV. The results of the experiments can be satisfactorily explained within the framework of the quasi-cubic approximation if allowance is made for the Heisenberg-Dirac exchange hamiltonian which describes the interaction between the magnetic moments of the band electrons and the magnetic moments localized at the impurity