Sr₂VO₃FeAs: A nanolayered bimetallic iron pnictide superconductor

One of the unifying concepts in the iron-pnictide superconductors, both for the mechanism of magnetic ordering and of unconventional order parameter character, has been the electron and hole Fermi surfaces that are approximately nested. Using the density functional methods that have predicted Fermi surfaces correctly in SrFe₂P₂, we find that the recently reported superconducting Sr₂VO₃FeAs, with T_c=37 K and no apparent competition between magnetism and superconductivity, possesses different Fermi surface geometry and character than previous classes of iron pnictides. The intervening layer (a V bilayer) gives rise to bands that cross the Fermi level. Coupling to the FeAs layer is small except for interaction along the zone boundary, however that coupling degrades the Fermi surface nesting. Sr₂VO₃FeAs, with its alternating layers of open-shell atoms, deserves further close study that should help to understand the origin of the properties of iron pnictide compounds.