We present a combined experimental and density functional theory study
of angle resolved photo emission spectroscopy (ARPES) and scanning
tunnelling spectroscopy (STS) in iron-pnictide superconductor.
The general assumption about these probes is that the penetration depth is large enough to probe bulk properties. For the ARPES case this is rather plausible given that kz-dispersions can be resolved. However, the presence of a surface leads to chemical effects like surface recharging buckling and even surface bands, which will alter the measured spectrum. Although, surface bands can be damped by experimental techniques, it is much less obvious how recharging and buckling effects the results. For STS the situation is even worse, given that the probe is a tunneling current, which inevitably must enter the sample via the surface. We will assess the strength of surface related complications in ARPES for 1111, 111 and 122 systems and give an interpretation of the STS spectra for Co-doped BaFe2As2.
