Yttrium iron garnet (YIG) is a kind of synthetic garnet, with chemical composition Y3Fe2(FeO4)3, or Y3Fe5O12. It is a ferrimagnetic material with Curie temperature 550 K.
In YIG, the five iron(III) ions occupy two octahedral and three tetrahedral sites, with the yttrium(III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in magnetic behaviour. By substituting specific sites with rare earth elements, for example, interesting magnetic properties can be obtained.
YIG has high Verdet constant which is applied to the Faraday effect, high Q factor in microwave frequencies, low absorption of infrared wavelengths up to 600 nm, and very small linewidth in electron spin resonance. These Properties make them useful for MOI (magnetic optical imaging) applications in superconductors.
YIG is used in microwave, optical, and magneto-optical applications, eg. microwave yttrium iron garnet filters. It is transparent for infrared light wavelengths over 600 nm. It finds use also in solid-state lasers in Faraday rotators, in data storage, and in various nonlinear optics applications.