Investigation of the Electronic Structure of BiFeO3 Epitaxial Films by Polarized X-Ray Absorption Spectroscopy

To investigate the epitaxial strain effect on local electronic structure of FeO6 octahedron of BiFeO3 epitaxial film, polarization-dependent Fe L23-edge x-ray absorption spectroscopy studies were performed on both tetragonal (T)-like BFO/LAO and rhombohedral (R)-like BFO/STO epitaxial films. Charge transfer multiplet theory based fittings were also performed to reveal the local electronic structure difference. Due to dramatic structural difference caused by epitaxial strain between these two samples, significant electronic structure differences were observed between these two specimens. For BFO/LAO, anisotropic electronic structure appears in vertically-elongated FeO6 octahedron and an additional shift of Fe ion off the central position is suggested. For BFO/STO, electronic structure is almost isotropic.