Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 34: SC: Iron-Based Superconductors - 122
TT 34.11: Talk
Thursday, March 25, 2010, 16:45–17:00, H20
Evidence of Two-Band Superconductivity in K- and Co-doped 122 Barium Iron Pnictides from Point-Contact Spectroscopy — •Michael Marz1, Oliver Berg1, Samuel Bouvron1, Thomas Wolf2, Hilbert v. Löhneysen1,2, and Gernot Goll1 — 1Physikalisches Institut, Karlsruher Institut für Technologie, 76131 Karlsruhe — 2Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe
Point-contact spectroscopy (PCS) experiments on superconducting iron pnictides were performed to investigate the structure of the supercondutive energy gap. We investigated K- and Co-doped BaFe2As2 single crystals in the superconducting state in the temperature range from T=2 K to T=30 K. We measured the differential conductance vs. voltage in superconductor/normal-metal point contacts using platinum as a normal-metal counterelectrode. Measurements were carried out with I⊥ c (’edge-to-edge’ method) and I∥ c (’needle-anvil’ geometry) to determine a possible orientation dependence. In all cases do the obtained spectra reveal signatures which we ascribe to the occurrence of two-band superconductivity in this material, in line with a recent analysis of high-resolution specific-heat measurements [1]. For a quantitative determination of the gap values, the spectra were analyzed within a modified BTK theory to describe two-band superconductivity.
[1] F. Hardy et al., archiv cond-mat 0910.5006.