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 Fe₃O₄ nanolayers. The magnetite layers were up to 5 nm thick and grew under the conditions at which Fe₂O₃ is thermodynamically stable. These Fe₃O₄ nanolayers act as buffer layers promoting a highly epitaxial growth of the hexagonal LuFeO₃ thin film up to 150 nm thick. Using scanning transmission electron microscopy, we show that the interface between (001) LuFeO₃ and (111) Fe₃O₄ 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.

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