A Relation between the Faraday Rotation and Sublattice Magnetization of YIG

The Faraday rotation θ of a YIG(Y 3 Fe 5 O 12 ) single crystal for an He–Ne laser light (λ=632.8 nm) is measured in magnetic fields H up to 45 kOe at temperatures T from 100 K through the Curie temperature (560 K) to 700 K. The results are well expressed by an equation θ= A M a + D M d +( a M a 2 + d M d 2 ) H , where M a and M d are sublattice magnetizations which depend on T and H , and A , D , a and d are constant parameters.