The saturation magnetization $M_s$, the uniaxial anisotropy $K_u$, the optical absorption $\alpha$, the Faraday rotation ${\theta }_F$, and the Faraday ellipticity ${\psi }_F$ of epitaxial garnet films of composition ${\mathrm{Gd}}_{3-x}{\mathrm{Bi}}_x{\mathrm{Fe}}_5{\mathrm{O}}_{12}$ have been investigated for $x\le 1.43$. The temperature dependence of $M_s$ and ${\theta }_F$ have been measured in the range 4.2 $\mathrm{K}\le T\le T_C$. The compensation temperature decreases and the Curie temperature increases linearly with the Bi content in accordance with data reported for bismuth-substituted yttrium iron garnets. The contribution of the bismuth to the rotation $\frac{{\Delta \theta }_F}{x}$ at $\lambda =633\mathrm{}$ nm was found to be -23 800 deg ${\mathrm{cm}}^{-1\mathrm{}}$ and -20 600 deg ${\mathrm{cm}}^{-1\mathrm{}}$ at $T=4.2\mathrm{}$ and 295 K, respectively. ${\theta }_F$ has been described in terms of the sublattice magnetizations inferred from the fit of the molecular-field theory to the saturation magnetization. The extracted magneto-optical coefficients exhibit a nonlinear variation with $x$ for both octahedral and tetrahedral sites. The growth-induced anisotropy shows a linear dependence on $x$ and reaches a value of 1.74 × ${10}^4$ J ${\mathrm{m}}^{-3\mathrm{}}$ at $x=1.43\mathrm{}$. The optical absorption was measured for wavelengths ranging between 500 and 800 nm.

• Received 3 August 1982

DOI:https://doi.org/10.1103/PhysRevB.27.4375