Magnetic and ferroelectric properties of epitaxial Sr-doped BiFeO3 thin films

Abstract We investigate the magnetic and ferroelectric properties of epitaxial Sr-doped BiFeO 3 , i.e., Bi 0.75 Sr 0.25 FeO 3−δ , thin films prepared by pulsed laser deposition. The films deposited at high oxygen pressure show a ferroelectric hysteresis loop at room temperature with remnant polarization of 2 P r = 86.13 μ C / cm 2 and coercive field of 2 E C = 75.5 kV / cm . Compared with the epitaxial BiFeO 3 thin film, the remnant polarization and coercive field of Bi 0.75 Sr 0.25 FeO 3−δ are small, probably due to the dilution of Bi 3+ ions, the existence of oxygen vacancies, and a small domain size. On the contrary, the films deposited at low oxygen pressure show a ferromagnetic hysteresis loop at room temperature. However, x-ray absorption and x-ray magnetic circular dichroism measurements show that the observed magnetic moment might be related to the formation of a γ - Fe 2 O 3 impurity phase.