Contributions of sublattices into the Faraday effect in rare earth ferrite-garnets

The present work aimed at studying the field and temperature dependences of the Faraday effect (FE) and at separating the sublattice contributions in the previously unexplored rare-earth ferrites-garnets of yttrium, samarium, europium, dysprosium, holmium, erbium, thulium, and lutecium. Single-crystal specimens 0.6 to 1.5 mm thick have been cut in the (111) plane. The Faraday rotation measurements have been carried out according to a scheme involving the polarization modulation. The measurements have been made at the wavelength of a helium-neon laser 1.15μ. The temperature of crystals has been varied between 77 and 550 deg K. The external magnetic field being as high as 20 koe. The error of the measurements has been 2-3 at room temperature and 0.3-0.5 in measuring the temperature behaviour of the FE. On the basis of the obtained results and the literature data on the temperature dependences of magnetizations and susceptibilities of garnets, the gyroelectric and gyromagnetic contributions from the magnetic sublattices to the observed FE have been separated. The separation has been achieved under the assumption of the temperature-independent specific contribution from sublattices. It has been shown that the changes in the FE in the region of magnetic saturation may be satisfactorily explained if the relative orientation of sublattices and their susceptibilities in the external magnetic field are taken into account. In the ferrites-garnets of dysprosium, erbium and holmium, the values of 0.29, 0.24, and 0.27, respectively, have been obtained for the gyromagnetic contributions. In all the garnets investigated, the gyroelectrical contribution from the octahedral sublattices exceeds that from the tetrahedral sublattices. The value of rare-earth sublattice contributions found by different methods are in good agreement with one another