Anisotropic Energy Gaps of Iron-based Superconductivity from Intra-band   Quasiparticle Interference in LiFeAs
  If strong electron-electron interactions between neighboring Fe atoms mediate the Cooper pairing in iron-pnictide superconductors, then specific and distinct anisotropic superconducting energy gaps \Delta_i(k) should appear on the different electronic bands i. Here we introduce intra-band Bogoliubov quasiparticle scattering interference (QPI) techniques for determination of \Delta_i(k) in such materials, focusing on LiFeAs. We identify the three hole-like bands assigned previously as \gamma, \alpha_2 and \alpha_1, and we determine the anisotropy, magnitude and relative orientations of their \Delta_i(k). These measurements will advance quantitative theoretical analysis of the mechanism of Cooper pairing in iron-based superconductivity. 
M. P. Allan, A. W. Rost, A. P. Mackenzie, Yang Xie, J. C. Davis, K.   Kihou, C. H. Lee, A. Iyo, H. Eisaki, and T.-M. Chuang
cond-mat.supr-con