Abstract:
Ultrathin films of yttrium-iron garnets with bismuth (Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$) on sapphire substrates (r-Al$_2$O$_3$) have been synthesized by magnetron sputtering. The spectral dependences of the Faraday effect and the polar Kerr effect in Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$/r-Al$_2$O$_3$ thin-film nanostructures are considered. The dispersion of the Verdet constant and the polar Kerr effect for a substrate made of monocrystalline diamagnetic r-Al$_2$O$_3$ has been measured. The spectral and field dependences of the Faraday and Kerr rotations of Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$ films have been determined. It is shown that the diamagnetic transparent substrate r-Al$_2$O$_3$ makes a weak contribution to the magneto-optical characteristics of thin-film nanostructures. The presence of magnetic inhomogeneities as a result of island growth of Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$ films on r-Al$_2$O$_3$ is accompanied by a significant decrease in the magnitude of the Faraday and Kerr effects. At the same time, the magnitude of the effects in the Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$ films grown on r-Al$_2$O$_3$ still is the same order to that of BiY$_2$Fe$_5$O$_{12}$ films on garnet substrates, which opens up prospects for wider use of Bi$_x$Y$_{3-x}$Fe$_5$O$_{12}$/r-Al$_2$O$_3$ structures either for research purposes or for practice.
Fulltext:
PDF file (1065 kB)