Electronic structure of new iron-based superconductors: From pnictides to chalcogenides and other similar systems

The electronic spectra of new iron-based high-temperature superconductors and a number of other chemically similar compounds have been discussed and compared with the focus on iron chalcogenide K1 - x Fe2 - y Se-2 and isostructural pnictide BaFe2As2 (122). It has been shown that the Fermi surfaces in K1 - x Fe2 - y Se-2 are significantly different from those in pnictides. The LDA + DMFT and LDA' + DMFT calculations have demonstrated that the effect of electron correlations in K1 - x Fe2 - y Se-2 on the electronic structure is much stronger than that in the most studied 122 system. The electronic structure of several multiband superconductors similar in chemical composition to iron-based high-temperature superconductors, but having a relatively low T (c) value (such as SrPt2As2, APt(3)P (A = Sr, Ca, La), and (Sr, Ca)Pd2As2), and the non-superconducting compound BaFe2Se3 has also been discussed. It has been shown that the electronic structure of these systems is significantly different from previously studied iron pnictides and chalcogenides. The T (c) value in these systems can be understood within the simple Bardeen-Cooper-Schrieffer model.