Electrical and magnetic properties of Aurivillius phase Bi5Fe1-xNixTi3O15 thin films prepared by chemical solution deposition

The Aurivillius Bi5Fe1-xNixTi3O15 (BFNT-x) (0≤x≤0.5) thin films were deposited by chemical solution deposition route. The microstructures, electrical and magnetic properties were systematically investigated in BFNT films. It has been found that the c-orientation of the films increases with the increase of Ni content. The coexistence of weak ferromagnetism and ferroelectricity at room temperature were observed in BFNT films except the x = 0.5 sample. The BFNT-0.1 sample exhibits a maximum remnant polarization 2Pr ∼49.3 μC/cm2, which is enhanced by 12.6% compared with that of the Ni-free thin film. The leakage current is decreased evidently with Ni content less than 0.3. The BFNT-0.1 film also shows the highest remnant magnetization 2Mr ∼2.14 emu/cm3. The origins of weak ferromagnetism in the BFNT films are attributed to the spin canting of the antiferromagnetic (AFM) coupling caused by Dzyaloshinskii-Moriya (DM) interaction based the Fe-O and Ni-O octahedral and affected by other causes as discussed. The saturation magnetization values of in-plane loops are smaller than that of the out-of-plane loops, indicating obvious anisotropic magnetism. These results demonstrate that partial substitution of Ni for Fe is an effective way for improving the multiferroic properties of Aurivillius compounds.