Bismuth Substituted Yttrium Iron Garnet Single Crystal Films Prepared by Sol-gel Method

Magneto-optic Faraday rotation effect and the amount of bismuth substituted in yttrium iron garnet single crystal films prepared by gel-coating on modified gadolinium-gallium garnet substrates are investigated, where the gel is synthesized by a sol-gel reaction of nitrates and ethylene glycol. The coated gel is annealed in air at temperatures up to 660 ℃ for 4 h, which is about 300 ℃ lower than that of liquid-phase epitaxy. The maximum amount of Bi substitution is x =2.7 and the crystallization temperature of garnet phase decreases with the increase of x down to 520 ℃ for x =2.7. In this film, a huge Faraday rotation of -8.1×10 4 (°)/cm at λ =0.633 μm is obtained.