Electronic structure of the BaFe2As2 family of iron-pnictide superconductors

We use high-resolution angle-resolved photoemission to study the electronic structure of the BaFe2As2 pnictides. We observe two electron bands and two hole bands near the X point, (pi,pi) of the Brillouin zone, in the paramagnetic state for electron-doped Ba(Co0.06Fe0.94)(2)As-2, undoped BaFe2As2, and hole-doped Ba0.6K0.4Fe2As2. Among these bands, only the electron bands cross the Fermi level, forming two electron pockets around X while the hole bands approach but never reach the Fermi level. We show that the band structure of the BaFe2As2 family matches reasonably well with the prediction of local-density approximation calculations after a momentum-dependent shift and renormalization. Our finding resolves a number of inconsistencies regarding the electronic structure of pnictides.