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