At the workshop this week Luca de' Medici gave a nice talk, based on work described in a preprint Selective Mottness as a key to iron superconductors with Gianluca Giovannetti, Massimo Capone
They argue that the best way to understand the iron superconductors is in terms of Hund's rule coupling and the total orbital filling. Thus the "parent compounds" which are antiferromagnetic should be viewed as being at 0.2 doping because they have 5 electrons in 3 degenerate iron orbitals. If one airbrushes out the antiferromagnetic phase one is left with the phase diagram below.
"momentum selective" Mott insulator.