Reconstruction of the polar interface between hexagonal LuFeO₃ and intergrown Fe₃ O₄ nanolayers

We report the observation of an unusual phase assembly behavior during the growth of hexagonal LuFeO₃ thin films which resulted in the formation of epitaxial Fe₃ O₄ nanolayers. The magnetite layers were up to 5 nm thick and grew under the conditions at which Fe₂ O ₃ is thermodynamically stable. These Fe₃ O₄ nanolayers act as buffer layers promoting a highly epitaxial growth of the hexagonal LuFeO 3 thin film up to 150 nm thick. Using scanning transmission electron microscopy, we show that the interface between (001) LuFeO 3 and (111) Fe₃ O₄ can be reconstructed in two ways depending on the sequence in which these compounds grow on each other. We suggest the polarity of the interface is the reason behind the observed interface reconstruction and epitaxial stabilization of magnetite.