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

摘要

We investigate the magnetic and ferroelectric properties of epitaxial Sr-doped BiFeO3, i.e., Bi0:75Sr0:25FeO3, thin films prepared by pulsed laser deposition. The films deposited at high oxygen pressure showa ferroelectric hysteresis loop at room temperature with remnant polarization of 2Pr D 86:13 mC=cm2and coercive field of 2EC D 75:5 kV=cm. Compared with the epitaxial BiFeO3 thin film, the remnantpolarization and coercive field of Bi0:75Sr0:25FeO3 are small, probably due to the dilution of Bi3C ions,the existence of oxygen vacancies, and a small domain size. On the contrary, the films deposited at lowoxygen pressure show a ferromagnetic hysteresis loop at room temperature. However, x-ray absorptionand x-ray magnetic circular dichroism measurements show that the observed magnetic moment mightbe related to the formation of a -Fe2O3 impurity phase.