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/spectroscopy on the A-122 iron pnictide superconductors - in this case BaFe${}_{2-x}$Co${}_x$As${}_2$ - involve a strong adatom filtering of the differential conductance from the near-EF Fe3d states, which in turn originates from the top-most sub-surface 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 an energy-dependent contrast inversion.

4.5 pages, 4 figures. To appear in Physical Review Letters

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Cited by in corpus (1)

• Enhanced Surface Superconductivity in Ba(Fe${}_{0.95}$Co${}_{0.05}$)${}_2$As${}_2$