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arXiv · 1207.7122

Surface adatom conductance filtering in scanning tunneling spectroscopy of Co-doped BaFe2As2 iron pnictide superconductors

K. Koepernik·S. Johnston·E. van Heumen·Y. Huang·J. Kaas·J. B. Goedkoop·M. S. Golden·Jeroen van den Brink
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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.

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K. Koepernik, S. Johnston, E. van Heumen, Y. Huang, J. Kaas, J. B. Goedkoop, M. S. Golden, Jeroen van den Brink. 2012-07-30. Surface adatom conductance filtering in scanning tunneling spectroscopy of Co-doped BaFe2As2 iron pnictide superconductors. https://doi.org/10.1103/physrevlett.109.127001

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