Electronic structure of Ca10(Pt4As8)(Fe2-xPtxAs2)5 with metallic Pt4As8 layers: An angle-resolved photoemission spectroscopy study

We studied the low-lying electronic structure of the newly discovered iron-platinum-arsenide superconductor, Ca-10(Pt4As8)(Fe2-xPtxAs2)(5) (T-c = 22 K) with angle-resolved photoemission spectroscopy. We found that the Pt4As8 layer contributes to a small electronlike Fermi surface, indicative of metallic charge reservoir layers that are rare for iron based superconductors. Moreover, the electronic structure of the FeAs layers resembles those of other prototype iron pnictides to a large extent. However, there is only d(xy)-orbital originated holelike Fermi surface near the zone center, which is rather strange for an iron pnictide superconductor with relatively high superconducting transition temperature; and the d(xz) and d(yz) originated bands are not degenerate at the zone center. Furthermore, all bands near the Fermi energy show negligible k(z) dependence, indicating the strong two-dimensional nature of this material. Our results indicate this material possesses a rather interesting electronic structure, which enriches our current knowledge of iron based superconductors.