Improved photomagnetoelectric properties of BiFeO3/CoFe2O4 films by using the size effect

The potential applications of magnetoelectric composites in capacitors, sensors, memory electronic devices, and energy harvesting devices have aroused great interest due to their mutual coupling between ferroelectric and ferromagnetic phases. In this paper, BFO/CFO composite films were prepared by the sol–gel method, and the regulation of magneto-photoelectric and coupling properties of BFO/CFO films with different compositions was studied. The results show that with the increase of BFO composition, the interface between BFO layer and BFO layer also appears, the dielectric constant of the film decreases with increasing the content of BFO, and the photoelectric conversion efficiency of the film increases at first and then decreases with the increase of BFO content. When the composition is 4BFO/6CFO, the photoelectric conversion efficiency of the composite film is the highest, which is 2.02 × 10−3%. With the increase of CFO content, the remanent magnetization and saturation magnetization of the film increase gradually. However, when the compositions are 4BFO/6CFO and 3BFO/7CFO, their leakage current is high, resulting in the degradation of ferroelectric properties. The composition 5BFO/5CFO has the highest magnetodielectric and photo induced magnetodielectric response, the corresponding values are 2.21% and 3.88%, respectively. The magnetoelectric coupling coefficient of the film is greatly increased under the action of light, reaching 115%, which could plausibly relate to the photovoltaic effect and the photostriction effects of the film. These results may provide good guidance on designing new photoelectromagnetic detector.