Sr ₂ VO ₃ FeAs: A nanolayered bimetallic iron pnictide superconductor

Abstract

One of the unifying concepts in the iron-pnictide superconductors, both for\nthe mechanism of magnetic ordering and of unconventional order parameter\ncharacter, has been the electron and hole Fermi surfaces that are approximately\nnested. Using the density functional methods that have predicted Fermi surfaces\ncorrectly in SrFe$_2$P$_2$, we find that the recently reported superconducting\nSr$_2$VO$_3$FeAs, with $T_c$=37 K and no apparent competition between magnetism\nand superconductivity, possesses different Fermi surface geometry and character\nthan previous classes of iron pnictides. The intervening layer (a V bilayer)\ngives rise to bands that cross the Fermi level. Coupling to the FeAs layer is\nsmall except for interaction along the zone boundary, however that coupling\ndegrades the Fermi surface nesting. Sr$_2$VO$_3$FeAs, with its alternating\nlayers of open shell atoms, deserves further close study that should help to\nunderstand the origin of the properties of iron pnictide compounds.\n