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.