Unfolding the electronic structure of Ca 10 (Fe 1 - X Pt x As) 10 (Pt n As 8)

The iron platinum arsenides Ca10(Fe1-xPtxAs)10(PtnAs8) are the first Fe-based superconductors with metallic spacer layers. Furthermore they display a large variation in their critical temperatures depending on the amount of Pt in their spacer layers: (n=3,4). To gain more insight into the role of the spacer layer the electronic structures of the iron platinum arsenides are represented in the momentum space of the underlying Fe sublattice using a first-principles unfolding method. We find that Ca10(FeAs)10(Pt4As8), contrary to Ca10(FeAs)10(Pt3As8), shows a net electron doping and a non-negligible interlayer coupling. Both effects could account for the difference in the critical temperatures.