Core Level and Valence Band Study of LaO$_{0.9}$F$_{0.1}$FeAs

TL;DR

This study uses photoemission spectroscopy to analyze the electronic structure of LaO$_{0.9}$F$_{0.1}$FeAs, revealing key features related to its superconducting and magnetic properties, including pseudogap behavior and temperature-dependent DOS changes.

Contribution

First comprehensive characterization of the orbital character and hybridization energy in LaO$_{0.9}$F$_{0.1}$FeAs using photoemission spectroscopy, linking electronic features to magnetic and structural transitions.

Findings

Identification of pseudogap-like feature at 90K

Observation of a DOS change near 120K

Evidence of electron correlation and spin effects

Abstract

Using angle-integrated photoemission spectroscopy we have probed the novel LaO$_{0.9}$F$_{0.1}$FeAs superconductor over a wide range of photon energies and temperatures. We have provided the first full characterization of the orbital character of the VB DOS and of the magnitude of the d-p hybridization energy. Finally, we have identified two characteristic temperatures: 90K where a pseudogap-like feature appears to close and 120K where a sudden change in the DOS near E$_F$ occurs. We associate these phenomena with the SDW 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.