Enhancement of magneto-optical Faraday rotation by bismuth substitution in bismuth and aluminum substituted yttrium–iron–garnet single-crystal films grown by coating gels

The effect of bismuth substitution on the magneto-optical Faraday rotation of bismuth and aluminum substituted yttrium–iron–garnet (Y3−xBixFe4.2Al0.8O12, x=0 to 2.8) single-crystal films was investigated, where the films were prepared by coating gels involving the constituent metallic ions on single-crystal (GdCa)3(GaMgZn)5O12 garnet plates. The maximum amount of bismuth substitution that yields solely the garnet phase was x=2.5. The onset and the completion temperatures for crystal growth of garnet were decreased by bismuth substitution and were, respectively, 500 and 560 °C for x=2.5. A marked increase in the Faraday rotation θF was observed at heavy substitution x≥2.0 and θF at 3.06 eV (λ=405 nm) was 36.6 deg/μm, but no substantial improvement in the figure of merit for Faraday effect θF/α, where α is the absorption coefficient, was recognized.