An Investigation On The Magnetooptic And Magnetic-Properties Of Tb-Yig

The calculations of the spontaneous electric Faraday rotation (FR) and the magnetization contributed by Tb3+ ions in Tb substituted iron garnets based on the quantum theory are presented. The crystal field (CF) and the superexchange interaction are two crucial factors in determining FR and the magnetization. Every CF splitting level is nondegenerate. But the energy differences between the lowest seven CF split levels of the ground configuration are not very large comparing with the superexchange interaction upon the Tb3+ ions, so the strong admixing of these levels by the high-order perturbation of the exchange interaction makes FR and the magnetization not small. Except FR below 150 K, the calculated results are in good agreement with experiments.