A review of the electronic structure of CaFe(2)As(2) and FeTe(0.6)Se(0.4)
Fe-based superconductors have drawn much attention during the last decade due to the finding of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity & magnetism. Extensive study of the electronic structure of these systems suggested dominant role of d states in their electronic properties, whereas the cuprate superconductors show major role of the ligand derived states. In this article, we review some of our results on the electronic structure of these fascinating systems employing high resolution photoemission spectroscopy. The combined effect of electron correlation and covalency reveal an interesting scenario in their electronic structure. The ligand p states contribution at the Fermi level is found to be much more significant than that indicated in earlier studies. Temperature evolution of the energy bands reveals signature of transition akin to Lifshitz transition in these systems.