Faraday rotation and sensitivity of (100) bismuth-substituted ferrite garnet films

We have investigated the Faraday rotation of in-plane magnetized bismuth-substituted ferrite garnet films grown by liquid phase epitaxy on (100) oriented gadolinium gallium garnet substrates. The Faraday spectra were measured for photon energies between 1.7 and 2.6 eV. To interpret the spectra, we use a model based on two electric dipole transitions: one tetrahedral and one octahedral. Furthermore, the Faraday rotation sensitivity was measured at 2.3 eV, and found to be in good agreement with the theoretical predictions. In particular, we find that the sensitivity increases linearly with the bismuth content and nonlinearly with the gallium content.