Electronic structure ofLaFeAsO1−xFxfrom x-ray absorption spectroscopy

T. Kroll, S. Bonhommeau, T. Kachel, H. A. Dürr, J. Werner, G. Behr, A. Koitzsch, R. Hübel, S. Leger, R. Schönfelder, A. K. Ariffin, R. Manzke (+5 others)
2008 Physical Review B  
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
more » ... rther 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.
doi:10.1103/physrevb.78.220502 fatcat:3af2yy25fndwpbh5lncivp6nse