High field magneto-optical study of yttrium iron garnet (YIG)

The temperature (5–300 K) and field (0–100 kG) variation of the Faraday rotation of yttrium iron garnet single crystals has been measured at selected wavelengths in the range 0.8–1.6 μm. Above the magnetic saturation field of a few kG the Faraday rotation is found to decrease with increasing field for all temperatures and wavelengths. It is shown that a field dependence of the magneto-optical coefficients causes this surprizing effect.