On the electronic structure of electron doped LaOFeAs as seen by X-ray absorption spectroscopy
/ Authors
T. Kroll, S. Bonhommeau, T. Kachel, H. Duerr, J. Werner, G. Behr, A.Koitzsch, R. Huebel, S. Leger, R. Schoenfelder
and 7 more authors
A. Ariffin, R. Manzke, F. Groot, J. Fink, H. Eschrig, B. Buechner, M. Knupfer
/ Abstract
We investigated the recently found superconductor LaO_{1-x}F_xFeAs by X-ray absorption spectroscopy (XAS). From a comparison of the O K-edge with LDA calculations we find good agreement and are able to explain the structure and changes of the spectra with electron doping. An important result from this edge is a limitation of the Hubbard U to values not significantly larger than 1 eV. From experimental Fe L_2,3-edge spectra and charge transfer multiplet calculations we gain further information on important physical values such as hopping parameters, the charge transfer energy Delta, and the on-site Hubbard U. Furthermore we find the system to be very covalent with a large amount of ligand holes. A shift in the chemical potential is visible in the O K- and Fe L_2,3-edge spectra which emphasizes the importance of band effects in these compounds.
Journal: Physical Review B