Electronic structure of prototype AFe2As2 and ReOFeAs high-temperature superconductors: A comparison

We have performed ab initio LDA calculations of the electronic structure of newly discovered prototype high-temperature superconductors AFe 2 As 2 (A = Ba, Sr) and compared it with the previously calculated electronic spectra of ReOFeAs (Re = La, Ce, Pr, Nd, Sm). In all cases, we obtain almost identical densities of states in a rather wide energy interval (up to 1 eV) around the Fermi level. Energy dispersions are also very similar and almost two dimensional in this energy interval, leading to the same basic (minimal) model of the electronic spectra, determined mainly by Fe d orbitals of the FeAs layers. The other constituents, such as A ions or rare-earth Re (or oxygen states) are more or less irrelevant for superconductivity. LDA Fermi surfaces for AFe 2 As 2 are also very similar to that of ReOFeAs. This makes the more simple AFe 2 As 2 a generic system to study the high-temperature superconductivity in FeAs-layered compounds.