Main factors in determining the magneto-optical behavior of rare-earth compounds

Abstract Some microscopic factors in the occurring of the Faraday rotation (FR) in the ferrimagnetic Ce-substituted iron garnet Ce x Y 3− x Fe 5 O 12 are analyzed using the quantum theory. One crucial factor is the superexchange interaction; FR scales linearly with this interaction. However, it approaches saturation as the superexchange interaction becomes several times larger than its normal value and then decreases. The spin–orbit (SO) coupling of the ground configuration has also a great influence on the FR. However, the dependency of FR on the SO coupling strength is rather complex.