Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 92: Superconductivity: Fe-based Superconductors - Theory II
TT 92.2: Talk
Thursday, April 3, 2014, 15:15–15:30, HSZ 201
Superconductivity from repulsion in LiFeAs: novel s-wave symmetry and potential time-reversal symmetry breaking — •Felix Ahn1, Ilya Eremin1, Johannes Knolle2, Volodymyr Zabolotnyy3, Sergey Borisenko3, Bernd Büchner3, and Andrey Chubukov4 — 1Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany — 2Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany — 3Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, D-01171 Dresden,Germany — 4Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
Using the ten orbital tight-binding model, derived from the ab-initio LDA calculations and fitted to the ARPES experiments, we analyze the structure of the superconducting gap in LiFeAs. We treat superconductivity as quasi-2D and decompose the pairing interaction for various kz cuts into s− and d-wave components. Analyzing the leading superconducting instabilities we find that in addition to the conventional s+−-wave order parameter where the gap changes sign between electron and hole pockets LiFeAs possesses another instability where the superconducting gap also changes sign between two smaller inner hole pockets. This occurs due to relatively large repulsion between these two small pockets and also relatively weak interaction between outer and inner hole pockets. The sizes of the gaps on the inner hole pockets is larger than the average value of the superconducting gap on the outer hole pockets and electron pockets which agrees with experimental data.