Effects of annealing process on asymmetric coercivities of Mn-doped BiFeO3 thin films

5% Mn-doped BiFeO3 (BFMO) thin films were deposited onto indium tin oxide electrodes using the sequential layer (BFMOSLA) and the conventional (BFMOCA) annealing processes. X-ray photoelectron spectroscopy results reveal that, in comparison with the BFMOCA film, the BFMOSLA film has lower content of Fe2+, which in turn leads to the fact that a larger remanent polarization can be observed in the latter film. On the other hand, the effects of the annealing process on the asymmetry of coercivity in BFMO are investigated. We find that asymmetric coercivities of BFMO films should originate from the preferential polarization direction and the aging of the films can render the asymmetry more severe.