Stabilisation of Fe(2)O(3)-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO(3) Films

Researchers have demonstrated that BiFeO(3) exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO(3) based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe(2)O(3)-rich perovskite nanophase, with an approximate formula (Fe(0.6)Bi(0.25)Nd(0.15))(3+) Fe(3+)O(3), formed within epitaxial Ti and Nd doped BiFeO(3) perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe(2)O(3)-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe(2)O(3) has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe(2)O(3). This finding is therefore significant not only to the thin film but also to the high-pressure community.