Ferroelectric properties of multiphase Bi–Fe–O thin films

We report on the ferroelectric properties of multiphase BiFeO3 thin films grown under varying oxygen deposition pressures. The dominant phases formed in the film change continuously from a mixture of BiFeO3 and Bi2O3 to a mixture of BiFeO3 and Fe2O3 as the pressure is varied. X-ray diffraction and transmission electron microscopy revealed that an epitaxial nanocomposite of BiFeO3 and Fe2O3 grew at deposition pressures of approximately 20 mTorr. The BiFeO3 grains in the BiFeO3–Fe2O3 nanocomposites were completely relaxed and unstrained. At room temperature the BiFeO3–Fe2O3 nanocomposite film was characterized by a high switchable polarization (60 μC/cm2) and a low leakage current density (≈ 1 × 10− 4 A/cm2 at 250 kV/cm).