Magneto-optical properties of (BiGdY) iron garnets for optical magnetic field sensors

The influence of the magnetization process of the stripe domain both on the linearity error and the temperature dependence of the sensitivity in (BiGdY)3Fe5O12 films for optical magnetic field sensors are studied. By measuring the dc applied field dependence of the light beam diffraction angle by the periodic magnetic domain structure, the domain period and the reduced thickness τ were determined. The magnetization curves calculated for the measured τ parameter show good agreement with the experimental results on the output characteristics. The linearity error of the ac Faraday output were within ±1% in the external field ranging of 10–300 Oe. However, a large linearity error was observed in the small field range. It was also found that the sensitivity is not affected by the temperature dependence of the τ parameter.