  The orbital symmetries of electron doped iron-arsenide superconductors
Ba(Fe1-xCox)2As2 have been measured with x-ray absorption spectroscopy. The
data reveal signatures of Fe d electron itinerancy, weak electronic
correlations, and a high degree of Fe-As hybridization related to the bonding
topology of the Fe dxz+yz states, which are found to contribute substantially
at the Fermi level. The energies and detailed orbital character of Fe and As
derived unoccupied s and d states are found to be in remarkably good agreement
with the predictions of standard density functional theory.
