Valence states of transition-metal ions in cubic perovskites SrMn1-xFexO3

초록

The electronic structures of SrMn1-xFexO3 (0 <= x <= 1) have been investigated by using photoemission spectroscopy (PES) and soft x-ray absorption spectroscopy (XAS). Mn ions in SrMnO3 are found to be in the nearly tetravalent (Mn4+) states, but with a small mixture of the Mn2+ configuration. With increasing x in SrMn1-xFexO3, Mn ions remain in the 4+ states. Fe ions in SrMn1-xFexO3 are also in the nearly tetravalent (Fe4+) states for the whole range of x. Valence-band PES reveals that the occupied Mn t(2g)(3) states are located about 2.5 eV below E-F, while the occupied Fe t(2g)(3)e(g)(1) states are broader than the Mn 3d occupied states, and are located between 3 and 6 eV below E-F. The large overlap between Fe 3d and the O 2p states is found in SrFeO3, reflecting the strong hybridization between the Fe 3d states and the O 2p states, in agreement with the metallic nature of SrFeO3. (c) 2007 American Institute of Physics.