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Functional renormalization-group study of the doping dependence of pairing symmetry in the iron pnictide superconductors

Ronny Thomale, Christian Platt, Jiangping Hu, Carsten Honerkamp, and B. Andrei Bernevig
Phys. Rev. B 80, 180505(R) – Published 13 November 2009

Abstract

We use the functional renormalization group to analyze the phase diagram of a four-band model for the iron pnictides subject to band interactions with certain A1g momentum dependence. We determine the parameter regimes where an extended s-wave pairing instability with and without nodes emerges. For electron doping, the parameter regime in which a nodal gap appears is in correspondence to recent predictions [A. Chubukov et al., arXiv:0903.5547 (unpublished)], however, at very low Tc. Upon hole doping, the s-wave gap never becomes nodal: above a critical strength of the intraband repulsion, the system favors an exotic extended d-wave instability on the enlarged hole pockets. At half filling, we find that a strong momentum dependence of interband pair hopping yields an extended s-wave instability instead of spin-density wave ordering. These results demonstrate that an interaction anisotropy around the Fermi surfaces generally leads to a pronounced sensitivity of the pairing state on the system parameters.

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  • Received 19 October 2009

DOI:https://doi.org/10.1103/PhysRevB.80.180505

©2009 American Physical Society

Authors & Affiliations

Ronny Thomale1, Christian Platt2, Jiangping Hu3, Carsten Honerkamp2, and B. Andrei Bernevig4

  • 1Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, D 76128 Karlsruhe, Germany
  • 2Theoretical Physics, University of Würzburg, D-97074 Würzburg, Germany
  • 3Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
  • 4Department of Physics, Princeton University, Princeton, New Jersey 08544, USA

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Issue

Vol. 80, Iss. 18 — 1 November 2009

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