Bismuth iron garnet films prepared by rf magnetron sputtering

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Abstract
We report on the growth of highly bismuth-substituted iron garnet films by rf magnetron sputtering in a pure argon plasma. Under special conditions the target composition is fully reproduced in the films. Film homogeneity in the noncrystalline state is excellent. Crystallization on lattice-matched garnet substrates occurring during growth above 520 °C substrate temperature and by post-annealing above 650 °C yields the garnet phase, as inferred from the optical and magneto-optic spectra and the saturation magnetization. Residual imperfections appearing after crystallization need further elucidation. We cope with the extreme disparity in the elemental sputter yields of the mixture Gd-Bi-Fe-Al-Ga-O by (i) protecting the growing film from ion bombardment in using a magnetron source and (ii) binding Bi to a more slowly sputtering species, such as in BiFeO3.