The effect of structural phase transition on the magnetic properties of BiFeO3 thin films

Bi 1-x Er x FeO 3 (x = 0, 0.05, 0.1 and 0.15 respectively) thin films were prepared by the ethylene glycol based sol–gel spin-coating method on cleaned Si (100) substrates. Effects of Er concentration on the phase formation, surface morphology and magnetic properties of BFO films were systematically investigated. Moreover, the oxidation state of Fe ion was studied by X-ray photoemission spectroscopy. X-ray diffraction and Raman spectroscopy indicated the substitutions of Er into the Bi site and a phase transition from rhombohedral to orthorhombic with Er-substitution. Scanning electron microscope and transmission electron microscope used to analyze the morphologies and microstructures of the thin films. In comparison with the other thin films studied here, the Bi 0.9 Er 0.1 FeO 3 thin film exhibited the largest magnetization and a smooth morphology. The possible reasons for the enhancement of the magnetization of these films were discussed.