Electronic structure of hole-doped Sr1+xLa1-xFeO4 studied by UPS and XAS

The electronic structure of K2NiF4-type Sr1+xLa1-xFeO4 compounds (0≤x≤0.3) was studied by ultraviolet-photoemission and x-ray-absorption spectroscopies. Resonant photoemission measurements demonstrated that although the satellite feature of Sr1-xLa1-xFeO4 was attributed to d4 final states, the whole valence band was constructed from well mixed Fe 3d and O 2p states. It was suggested that the parent Sr1+xLa1-xFeO4 compound is intermediate between Mott-Hubbard and charge-transfer insulators. O K-edge and Fe K-edge x-ray-absorption measurements showed that hole bands composed of O 2p and Fe 3d character were formed in the original conduction-band edge upon hole doping, while the valence-band structure obtained by nonresonant photoemission measurements did not change. Changes in the electrical and magnetic properties were correlated with those in electronic structure.