Orbital characterization of iron-pnictide high-temperature superconductors by angle resolved photoemission spectroscopy

The electronic structure of the optimally hole-doped pnictide compound Ba0:6K0:4Fe2As2 was obtained and studied by angle resolved photoemission spectroscopy (ARPES). The light polarization dependence of the bands is explained by the selection rules contained in the photoemission transition matrix elements, and gives novel information on the possible orbital character of the bands. The Fermi surface geometry also shows important variations with light polarization. An attempt is made to analyze its more complex link with the selection rules by taking a comparison with Fermi surface orbital character simulations. While some good correspondence can be observed, a number of inconstistancies and a large photon energy dependence seems to underline the importance of the more global matrix elements.