Anisotropic Energy Gaps of Iron-based Superconductivity from Intra-band Quasiparticle Interference in LiFeAs

Uneven Gap Electron pairs that are responsible for the phenomenon of superconductivity can only be broken by investing a finite amount of energy, called the energy gap. The size of the gap may depend on the position on the Fermi surface; in cuprates, the gap completely disappears at certain points. What happens in the pnictide superconductors is still a subject of debate, not least because there appear to be differences between the different pnictide families. Allan et al. (p. 563 ) used scanning tunneling spectroscopy to study the compound LiFeAs. The gap was mapped on three of the five bands on which the Fermi surface resides and was found to be anisotropic in momentum space.