Singlet two-electron states in superconducting materials based on iron pnictides

Abstract

Two-electron states with a zero pulse for the symmetry group of superconducting materials based on iron pnictides are considered. Cases are established for the introduction of one or two additional quantum numbers, notably, the internal quantum number, which characterizes single-electron states, or an additional quantum number, i.e. the irreducible representation index of the intermediate group. The octet structure of zeros observed in photoelectron spectra and the phase difference between the two-electron states on various Fermi surfaces are interpreted.