ENHANCEMENT OF MAGNETOOPTICAL 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-degrees-C for x = 2.5. A marked increase in the Faraday rotation theta(F) was observed at heavy substitution x greater-than-or-equal-to 2.0 and theta(F) at 3.06 eV (lambda = 405 nm) was 36.6 deg/mu-m, but no substantial improvement in the figure of merit for Faraday effect theta(F)/alpha, where alpha is the absorption coefficient, was recognized.