Multiferroic properties of a YCrO3/BiFeO3 bilayered thin film prepared by a sol-gel method

YCrO3 (YCO), BiFeO3 (BFO), and YCrO3/BiFeO3 (YCO-BFO) thin films were prepared on quartz substrates using spin coating by a sol-gel method. X-ray diffraction demonstrated that YCO and BFO thin films had a perovskite orthorhombic, and rhombohedral structure, respectively. The stronger and sharper diffraction intensity of YCO-BFO bilayered thin film indicated that the bottom YCO layer was able to promote the grain growth of BFO film, which was further verified by scanning electron microscope. The ferroelectric test demonstrated that the leakage current density of YCO-BFO bilayered film was reduced by one order of magnitude compared to that of BFO film, which had a better ferroelectric property. Optical absorption spectra indicated that the band gap of YCO-BFO thin film was lower than that of BFO film, suggesting their potential application as UV and blue-green-driven photocatalysts. The magnetic test verified that the ferromagnetic property of YCO-BFO film was obviously enhanced compared to those of BFO and YCO thin films. The results revealed that YCO layer played an important role for improving multiferroic properties of BFO thin film. The mechanisms of the effects of bottom YCO layer on optical and multiferroic properties of BFO thin film in the YCO-BFO bilayered film were discussed in detail.