Abstract
Two distinctive perturbation schemes are employed to study the effect of uniaxial stress on the zero-field splitting of Mn2+ ions in MgO, MnO, CaO and SrO crystals. It is found that the effect can be explained well in terms of the spin-orbit coupling mechanism if the crystal-field parameters are used for fitting the optical spectra. The theory predicts G11>0 and G446S-state ion in an Oh crystal.