Electronic Structure of Sr₃Fe_2−xCo_xO_7−δ Studied by Photoemission and X-ray Absorption Spectroscopy

Abstract

We have investigated the electronic structure of Sr 3 Fe 2−x Co x O 7−δ using photoemission and soft xray absorption spectroscopy (XAS). From the analysis on the O 1s, Fe 2p, and Co 2p core level photoemission spectra and the line-shape analysis on the Fe and Co L 2,3 edge XAS spectra, we concluded that the valence of Fe and Co are both ∼3.85+, the expected value. From the analysis of 2p−3d resonant photoemission spectra, we found that the electron density of states near the Fermi level has a dominant Fe 3d character and the Co 3d states are located below the Fe 3d states by ∼1 eV, in agreement with the smaller charge-transfer energy of Co 4+ than that of Fe 4+ .