Susceptibility Tensor and the Faraday Effect in Ferrimagnetics

Abstract

The components of the susceptibility tensor have been calculated for the two-sublattice model of a ferrimagnetic in which damping is neglected, and the results related to the theory of the Faraday effect in these materials. It is shown that in most cases the only change necessary is the replacement of the electron gyromagnetic ratio by the effective gyromagnetic ratio of the material. The effect of the sublattice structure is more apparent when the material has a compensation point, for then the rotation can change sign two or more times as a function of temperature or composition. The rotation to be expected for an unmagnetized antiferromagnetic is also determined, and some of the simpler results are generalized to the case in which there are an arbitrary number of sublattices. Other possible sublattice effects are also briefly considered.