Results of Magneto-Optical Investigation of Rare-Earth Iron Garnets

Abstract

The fine structure of the 7F0→7F4 absorption line of the Eu3+ ion in single crystals of europium iron garnet has been studied. The magneto-optical method allows us to evaluate the contributions of magnetic and electric dipole transitions to the absorption coefficient of the garnet. Anisotropy in the structure of the line was observed, the intensities of individual components depending on the relative orientation of the plane of the polarized light and on the magnetization vector of the crystal. The main components of the line are shown to arise from an exchange Zeeman effect. From the magnitude of the splitting the exchange field acting on the Eu3+ ion is found to be 220 000 Oe. Certain components of the fine structure are interpreted in terms of combination lines involving spin-wave modes in the garnet. Measurements of the Faraday rotation in europium, dysprosium, terbium, and samarium garnet in the infrared are described and used to calculate the g factor for the ground state of the rare-earth ion.