Effect of Mn substitution for multiferroic BiFeO3 probed by high-resolution soft-X-ray spectroscopy

The electronic structures of BiFeO3 (BF) and Mn-doped BiFeO3 [BF(Mn)] have been studied by X-ray absorption spectroscopy (XAS) and soft-X-ray emission spectroscopy (SXES). BF and BF(Mn) have a mixed valence state of Fe2+ and Fe3+. Their valence hand is mainly composed of the O 2p state hybridized with the majority-spin t(2g) and e(g) orbitals of Fe 3d state. The Conduction band is composed of the minority-spin t(2g) and e(g) orbitals of Fe 3d. The band gaps of BF and BF(Mn) are estimated to be 1.3 eV and 2.7 eV, respectively. The increasing in band gap with Mn substitution contributes to a change in the handwidth of the valence hand.