Structure and interface chemistry of perovskite-spinel nanocomposite thin films

The structure and the interface chemistry of epitaxial $BiFeO3–NiFe2O4$ nanocomposite thin films on $SrTiO3(001)$ substrates were investigated using the $Z$-contrast imaging and the electron exit-wave reconstruction methods at the atomic scale. The results show that the $NiFe2O4$ pillars are nonwetting with respect to the substrate and exhibit {111} facets at the surface. The interface between $BiFeO3$ and $NiFe2O4$ lies in the {110} planes and is semicoherent. The atomic configuration of the interface, with the BiFeO layer bonding to the $[Ni,Fe]O2$ layer, was shown to have the maximized structure continuity and minimized interface charging.