Polarization switching in epitaxial BiFeO3 films

Ferroelectric domain structure and polarization switching in an epitaxial $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ film grown on a 0.8° miscut $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3\left(001\right)$ substrate were studied by piezoelectric force microscopy. The film shows a two-domain stripe pattern, with the polarization vectors oriented along two ⟨111⟩ axes which form an angle of 71°. Polarization switching was investigated by locally poling the film. By combining the perpendicular and in-plane piezoresponse data we found that polarization rotates by 71° and 109°, while 180° switching is mainly observed at low fields.