Specifics of impurity effects in ferropnictide superconductors
  Effects of impurities and disorder on quasiparticle spectrum in superconducting iron pnictides are considered. Possibility for occurrence of localized energy levels due to impurities within the superconducting gap and the related modification of band structure and of superconducting order parameter are discussed. The evolution of superconducting state with impurity doping is traced. 
Y.G. Pogorelov, M.C. Santos, V.M. Loktev
cond-mat.supr-con