Ferromagnetic-like behaviour in bismuth ferrite films prepared by electrodeposition and subsequent heat treatment

Bismuth ferrite (BiFeO3) films (10 μm in thickness) are synthesized by electrodeposition from a dimethylformamide bath containing Bi and Fe nitrate salts as precursors followed by heat treatment in air. Thermal treatments are needed to induce crystallisation of the as-deposited amorphous-like films. A detailed morphological, structural and magnetic characterisation evidences that BiFeO3 forms in a rather narrow temperature window (around 600 °C). At lower and higher temperatures, secondary binary and ternary oxides are also formed. Soft ferromagnetic-like behaviour is observed in all films, which presumably arises from the obtained nanoscale structure, which favours the occurrence of spin canting in the BiFeO3 antiferromagnetic phase. The eventual contribution from secondary phases to the observed ferromagnetic-like response is also discussed. The obtained results are appealing for the integration of BiFeO3 into devices that may require relatively thick films with an enhanced surface area-to-volume ratio. The growth of this type of material by techniques other than electrodeposition is not straightforward.