Evolution of superconducting gap anisotropy in hole-doped 122 iron pnictides

Superconductivity in 122-Type Pnictides without Iron

The exploration of superconducting iron-free pnictides with a ThCr2Si2-type or related structure and the study of their superconducting properties are important in order to get a deeper understanding of the pairing mechanism of 122 iron pnictides. Here we review the properties of 122-type iron-free pnictides superconductors with structures similar to that of BaFe2As2. Evidence of fully gapped n...

Orbital-independent superconducting gaps in iron pnictides.

The origin of superconductivity in the iron pnictides has been attributed to antiferromagnetic spin ordering that occurs in close combination with a structural transition, but there are also proposals that link superconductivity to orbital ordering. We used bulk-sensitive laser angle-resolved photoemission spectroscopy on BaFe(2)(As(0.65)P(0.35))(2) and Ba(0.6)K(0.4)Fe(2)As(2) to elucidate the ...

Quasiparticle scattering interference in superconducting iron pnictides

Using both two orbital and five orbital models, we investigate the quasiparticle interference QPI patterns in the superconducting SC state of iron-based superconductors. We compare the results for nonmagnetic and magnetic impurities in sign-changed s-wave cos kx · cos ky and sign-unchanged cos kx · cos ky SC states. While the patterns strongly depend on the chosen band structure details, the se...

Momentum dependence and nodes of the superconducting gap in the iron pnictides

Using general symmetry arguments and model calculations we analyze the superconducting gap in materials with multiple Fermi-surface pockets, with applications to iron pnictides. We show that the gap in the pnictides has an extended s-wave symmetry but is either nodeless or has nodes, depending on the interplay between intraband and interband interactions. We argue that the nodes in the gap emer...

Anisotropy of Energy Gap in Superconducting Aluminum