Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 68: Superconductivity: Fe-based Superconductors - Theory I

TT 68.2: Talk

Wednesday, April 2, 2014, 15:30–15:45, HSZ 201

Suppression of T_c due to impurity scattering with a phase — •Mareike Hoyer¹, Sergey Syzranov^1,2, and Jörg Schmalian^1,3 — ¹Institut für Theorie der Kondensierten Materie, Karlsruher Institut für Technologie, Karlsruhe, Germany — ²Department of Physics, University of Colorado, Boulder, Colorado, USA — ³Institut für Festkörperphysik, Karlsruher Institut für Technologie, Karlsruhe, Germany

We consider weak disorder in a two-band superconductor and investigate the effect of a finite phase of the off-diagonal matrix element of the impurity potential in band representation. In particular, we analyze the impact on the superconducting transition temperature T_c. We concentrate on s⁺⁺ and s⁺⁻ symmetries of the superconducting order parameter which are widely discussed as possible candidates in iron pnictides.

We argue that the effect of impurity scattering on the transition temperature in complex materials such as iron pnictides cannot be reduced to the consideration of single-particle scattering rates. Depending on the phase φ, we find that nonmagnetic impurities can act as pair-breakers for the s⁺⁺ state while such impurities can leave T_c for the s⁺⁻ state unchanged.