OPTICALLY DETECTED MAGNETIC-RESONANCE VIA THE MAGNETIC CIRCULAR-DICHROISM OF ABSORPTION OF CERIUM IMPURITIES IN BULK PARAMAGNETIC TERBIUM GALLIUM GARNET

The paramagnetic resonance of dilute Ce3+ ions in the bulk paramagneti c host Tb3Ga5O12 is separated from the host response by means of optic ally detected magnetic resonance (ODMR) using the magnetic circular di chroism (MCD) of the absorption. This result shows that it is possible in principle to extend by means of the ODMR of the absorption the reg ime of paramagnetic resonance detection of impurity ions to magnetic h osts, which strongly interact with the microwave field and, hence, mak e the impurity signals unobservable by means of conventional EPR. The observed ODMR signals are attributed to Tb3+ and Ce3+ ions by correlat ion with the optical bands of these species. By means of ODMR via the Faraday effect it is shown that this effect is due to transitions betw een Tb levels. The identification of the observed magnetic resonance s tructures is confirmed by calculations based on known information on T b3+ and Ce3+ in diamagnetic hosts. The role of molecular fields is dis cussed.