The synthesis and microstructural, optical, magnetic characterizations of m 0 0-oriented epitaxial Bi₂Fe₄O₉ thin film by pulsed laser deposition

Mullite Bi₂Fe₄O₉ single crystal epitaxial thin film has been successfully synthesized on SrTiO₃ (1 0 0) substrate by pulsed laser deposition. The single crystal thin film is grown along (m 0 0) orientation (m = 2, 4) which is identified by X-ray diffraction. Morphology analysis shows orderly assigned grains with some small defects due to the volatilization of Bi₂O₃ tested by scanning electron microscope and atomic force microscopy. The chemical composition of film is confirmed by energy dispersive X-ray spectroscopy, nearly in accord with the chemical formula. M-H hysteresis curve confirms the ferromagnetism in single crystal thin film which can be attributed to canted non-collinear anti-ferromagnetic spin order caused by structural distortion. The band gap of thin film is calculated as 1.5 eV through transmission spectrum which is very suitable for solar cell. This research not only lay a solid foundation on further researching Bi₂Fe₄O₉ single crystal epitaxial film, but also open an avenue to design various multifunctional devices.