Core-level and valence-band study using angle-integrated photoemission onLaFeAsO0.9F0.1

Abstract

Using angle-integrated photoemission spectroscopy we have probed the novel ${\text{LaFeAsO}}_{0.9}{\text{F}}_{0.1}$ superconductor over a wide range of photon energies and temperatures. We have provided a full characterization of the orbital character of the valence-band (VB) density of states (DOS) and of the magnitude of the $d\text{\ensuremath{-}}p$ hybridization energy. Finally, we have identified two characteristic temperatures: 90 K where a pseudogap-like feature appears to close and 120 K where a sudden change in the DOS near ${E}_{F}$ occurs. We associate these phenomena with the spin density wave magnetic ordering and the structural transition seen in the parent compound, respectively. These results suggest the important role of electron correlation, spin physics, and structural distortion in the physics of Fe-based superconductors.