Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity: Fe-based Superconductors - 122 Part 1

TT 8.2: Talk

Monday, March 26, 2012, 15:15–15:30, H 2053

Pair-breaking in overdoped Ba(Fe_1−xCo_x)₂As₂: Evidence for s± superconductivity — •Frédéric Hardy, Robert Eder, Thomas Wolf, Rolf Heid, Philipp Burger, Anna Böhmer, Peter Schweiss, and Christoph Meingast — Institut für Festkörperphysik KIT, Karlsruhe, Germany

Using specific-heat measurements, we study the effect of disorder induced by Co substitution on the thermodynamic properties of overdoped Ba(Fe_1−xCo_x)₂As₂ (x>0.06) superconductors. We find that scattering of electrons by these non-magnetic impurities is rather strong (beyond Born limit) explaining the rapid suppression of T_c for x=0.12. The variation of the specific-heat discontinuity, the thermodynamic critical field, and the gapless contributions, with Co content can be accurately reproduced only if the superconducting ground state exhibits s± symmetry. Comparisons with other systems including K and P doped single crystals are given.