title: Surface adatom conductance filtering in scanning tunneling spectroscopy of co-doped BaFe2As2 iron pnictide superconductors.
abstract: We establish in a combination of ab initio theory and experiments that the tunneling process in scanning tunneling microscopy or spectroscopy on the A-122 iron pnictide superconductors-in this case BaFe(2-x)Co(x)As(2)-involves a strong adatom filtering of the differential conductance from the near-E(F) Fe-3d states, which in turn originates from the topmost subsurface Fe layer of the crystal. The calculations show that the dominance of surface Ba-related tunneling pathways leaves fingerprints found in the experimental differential conductance data, including large particle-hole asymmetry and energy-dependent contrast inversion in conductance maps.
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Koepernik
authors.forename: S
authors.initials: S
authors.lastname: Johnston
authors.forename: E
authors.initials: E
authors.lastname: van Heumen
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.forename: J
authors.initials: J
authors.lastname: Kaas
authors.forename: J B
authors.initials: JB
authors.lastname: Goedkoop
authors.forename: M S
authors.initials: MS
authors.lastname: Golden
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink