Magnetic, Optical and Microwave Properties of Rare-Earth-Substituted Fibrous Yttrium Iron Garnet Single Crystals Grown by Floating Zone Method

We studied the crystallographic, magnetic, optical and microwave propagation properties of fibrous rare-earth-substituted Y_2.7R_0.3Fe₅O₁₂ (R:YIG) single crystals, grown by a simple floating zone (FZ) method with yttrium aluminium garnet (YAG) laser heating assisted by infrared irradiation, for all rare-earth elements. The first purpose of our studies was to seek outstanding properties of R:YIG crystals and the second aim was to obtain data in order to develop crystals with complex properties, such as large Faraday rotation and low saturation magnetization, by substituting two or more rare-earth elements for Y into the YIG crystal. The lattice constant, saturation magnetization, Faraday rotation, optical absorption coefficient, full-width at half aximum (ΔH) of ferromagnetic resonance and microwave propagation in magnetostatic wave (MSW) modes were measured for R:YIG single crystals. Low saturation magnetization in Gd:YIG and Tb:YIG, large Faraday rotation in Ce:YIG and low loss propagation of MSW in Lu:YIG were found. Our comprehensive results will also contribute to identifying new materials applicable in for optical and microwave devices utilizing R:YIG crystals.