Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 70: Superconductivity: Fe-based Superconductors - Theory

TT 70.2: Talk

Thursday, March 23, 2017, 15:30–15:45, HSZ 103

Tilting the balance towards d-wave in iron-based superconductors — Mario Fink and •Ronny Thomale — Institut für Theoretische Physik, Universität Würzburg, 97074 Würzburg, Germany

The interplay of interactions and Fermi surface topology in iron-based superconductors can promote s-wave and d-wave superconductivity as competitive canditates. From the theoretical limit of zero temperature, we develop a phenomenological thermodynamic argument how a weak perturbation such as small but finite temperature or an applied Zeeman field H_z can favor a nodal d-wave state over a nodeless s-wave state. This preference occurs as the quasiparticles in the nodal regime gain energy by polarization with respect to the applied field, or generate entropy at small finite temperature. We speculate that K_xBa_1−xFe₂As₂ for large hole doping could be a viable scenario for such a magnetically or entropically induced transition from s-wave to d-wave superconductivity.