Epitaxially grown bismuth-substituted lutetium iron garnet films of composition ${\mathrm{Lu}}_{3\mathrm{-}\mathrm{x}}$${\mathrm{Bi}}_{\mathrm{x}}$${\mathrm{Fe}}_5$${\mathrm{O}}_{12}$ and (Lu,Y${)}_{3\mathrm{-}\mathrm{x}}$${\mathrm{Bi}}_{\mathrm{x}}$${\mathrm{Fe}}_5$${\mathrm{O}}_{12}$ have been investigated with respect to the bismuth-induced changes of the saturation magnetization $M_s$, the Curie temperature $T_C$, the growth-induced anisotropy $K_u^g$, the optical absorption α, and the Faraday rotation ${\theta }_F$. The composition and temperature dependence of $M_s$ and ${\theta }_F$ at λ=633 nm have been measured in the range 0≤x≤2.17 and 4.2 K≤T≤$T_C$, respectively, revealing basically the same dependences on x as observed for bismuth-substituted yttrium and gadolinium iron garnet films. In contrast to the latter compositions, $K_u^g$ turns out to be much smaller in lutetium-bismuth iron garnet films and is significantly increased by small yttrium additions. The temperature dependence of ${\theta }_F$ can be described in terms of the sublattice magnetizations using constant magneto-optical coefficients. The measured temperature dependence of $K_u^g$ is compared with calculated results based on the single-ion theory.

• Received 17 December 1984

DOI:https://doi.org/10.1103/PhysRevB.31.5858