Electronic structure of the BaFe₂ As₂ family of iron-pnictide superconductors

We use high-resolution angle-resolved photoemission to study the electronic structure of the BaFe₂ As₂ pnictides. We observe two electron bands and two hole bands near the X point, (π,π) of the Brillouin zone, in the paramagnetic state for electron-doped Ba (Co0.06 Fe0.94) 2 As ₂, undoped BaFe₂ As₂, and hole-doped Ba0.6 K0.4 Fe₂ As₂. 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 BaFe₂ As₂ 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.