Effective three-band structure in Fe-based superconductors

David Möckli; E. V. L. de Mello

doi:10.1209/0295-5075/109/17011

paper

Effective three-band structure in Fe-based superconductors

arXiv:1408.5884 · doi:10.1209/0295-5075/109/17011

Abstract

We present self-consistent calculations of the multi-gap structure measured in some Fe-based superconductors. These materials are known to have structural disorder in real space and a multi-gap structure due to the $3 d$ Fe-orbitals contributing to a complex Fermi surface topology with hole and electron pockets. Different experiments identify three s-wave like superconducting gaps with a single critical temperature ( $T_{c}$ ). We investigate the temperature dependence of these gaps by a multi-band Bogoliubov-deGennes theory at different pockets in the presence of effective hybridizations between some bands and an attractive temperature dependent intra-band interaction. We show that this approach reproduces the three observed gaps and single $T_{c}$ in different compounds of Ba $_{1 - x}$ K $_{x}$ Fe $_{2}$ As $_{2}$ , providing some insights on the inter-band interactions.

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The Ba $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ superconducting four-gap temperature evolution: a multi-band Chebyshev-BdG approach