Optomagnetic studies of the effect of mixing of electronic states of a rare-earth ion in erbium-yttrium aluminate-garnet

Fluorescence spectra and the degree of magnetic circular polarization of fl uorescence are studied in the region of the S-4(3/2) --> I-4(15/2) transiti on in a Er3+ ion in the Y3Al5O12 host. Unusual spectral dependence of the d egree of magnetic circular polarization is found for a number of lines of s econdary emission. Experimental results are interpreted with mixing of ener gy levels of magnetoactive ions taken into account. It is shown that mixing of electronic states of a Er3+ ion in the magnetic field not only varies o scillator strengths of radiative transitions, but also significantly affect s the shape of the corresponding fluorescence lines.