Electronic Structure of Prototype AFe2As2 and ReOFeAs High-Temperature Superconductors: a Comparison
Abstract
We have performed ab initio LDA calculations of electronic structure of newly discovered prototype high-temperature superconductors AFe2As2 (A=Ba,Sr) and compared it with previously calculated electronic spectra of ReOFeAs (Re=La,Ce,Pr,Nd,Sm). In all cases we obtain almost identical densities of states in 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 electronic spectra, determined mainly by Fe d-orbitals of FeAs layers. The other constituents, such as A ions or rare earths Re (or oxygen states) are more or less irrelevant for superconductivity. LDA Fermi surfaces for AFe2As2 are also very similar to that of ReOFeAs. This makes the more simple AFe2As2 a generic system to study high-temperature superconductivity in FeAs - layered compounds.