A detailed knowledge of the gap structure for the Fe-pnictide superconductors is still rather rudimentary with several conflicting reports of either nodes, deep gap minima, or fully isotropic gaps on the Fermi-surface sheets, both in the $k_x\text{−}{k}_y$ plane and along the $c$ axis. In this Rapid Communication, we present considerations for electronic Raman scattering which can help clarify the gap structure and topology using different light-scattering geometries. Using density-functional calculations for the Raman vertices, it is shown that the location of the gap minima may occur on loops stretching over a portion of the $c$ axis in $\text{Ba}{\left({\text{Fe}}_{0.94}{\text{Co}}_{0.06}\right)}_2{\text{As}}_2$.

• Received 30 July 2010

DOI:https://doi.org/10.1103/PhysRevB.82.180502