Effective three-band structure in Fe-based superconductors

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 3d 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-de Gennes 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-xK_xFe₂As₂, providing some insights into the inter-band interactions.