The growth window of multiferroic ${\text{BiFeO}}_3$ thin films is very small. Both temperature and oxygen pressure will affect the film quality and phase purity significantly. We demonstrate here that even within the window where phase pure ${\text{BiFeO}}_3$ thin films can be obtained, different oxygen partial pressures still lead to substantial variation in Bi/Fe ratio in the film, which closely link with the corresponding ferroelectric properties. Piezoelectric force microscopy also reveals significant difference in the domain structures of these films. A defect-dipole complex model is proposed to explain the difference in the electrical properties and domain structures for films grown under different oxygen pressures.

• Received 5 April 2009

DOI:https://doi.org/10.1103/PhysRevB.80.024105