Observation of structural transitions and Jahn–Teller distortion in LaMnO3-doped BiFeO3 thin films

Structural and functional properties of multiferroic BiFeO3 are currently under debate. We utilized Raman spectroscopy to characterize the structural properties of pure and up to 10mol% LaMnO3-doped polycrystalline BiFeO3 thin films. All films were identified as phase-pure perovskite using x-ray diffraction (XRD). Although XRD has insufficient sensitivity for detailed thin film analysis, Raman experiments showed that pure BiFeO3 structure is best described as monoclinic, and that doping with LaMnO3 causes substantial modifications, namely, Jahn–Teller distortions to the (Mn,Fe)3+O6 octahedra accompanied by structural transition toward orthorhombic. Manganese substitution is shown to be the main cause of these changes.