Epitaxial growth of BiFeO₃ thin films by LPE and sol-gel methods

Epitaxial BiFeO₃ thin films have been grown on the (0 0 1) SrTiO₃ and LaAlO₃ substrates by liquid phase epitaxy (LPE) and sol-gel methods. The films had an in-plane texture of 2° and out-plane texture of 0.6° and showed a 4-fold symmetry about the c-axis, indicating a distortion of the bulk rhombohedral cell to a tetragonal or cubic structure. The LPE films were both ferroelectric and ferromagnetic. The sol-gel films showed a small linear increase of the magnetisation with the applied magnetic field, indicating they possibly had the same antiferromagnetic behaviour as the bulk crystal. The LPE films exhibited a large leakage current, which probably originated from a relatively high level of Fe²⁺ in the films induced by the high growth temperature. Fe²⁺ might also account for the origin of the ferromagnetism in LPE films.