Microstructure of Bismuth-Doped Yttrium Iron Garnet Thin Films

Complex structural studies of nanosized bismuth-doped yttrium iron garnet (BYIG) films have been performed using X-ray diagnostics, scanning/transmission electron microscopy, and energy-dispersive X-ray microanalysis. The crystal structure of the film–substrate interface and near-surface layers, along with the change in the interplanar distance over the film thickness, have been determined. The following features of the film microstructure were revealed: the presence of pores, the absence of misfit dislocation at the interface, the formation of maghemite (γ-Fe₂O₃) particles on the film surface, and a decrease in the Bi content towards the film surface. Suggestions about the influence of the Bi content on the magneto-optical properties in dependence of the film thickness are made.