Electronic structure of optimally doped pnictide Ba_0.6K _0.4Fe₂As₂: A comprehensive angle-resolved photoemission spectroscopy investigation

The electronic structure of the Fe-based superconductor Ba _0.6K_0.4Fe₂As₂ is studied by means of angle-resolved photoemission. We identify dispersive bands crossing the Fermi level forming hole-like (electron-like) Fermi surfaces (FSs) around Γ (M) with nearly nested FS pockets connected by the antiferromagnetic wavevector. Compared to band structure calculation findings, the overall bandwidth is reduced by a factor of 2 and the low energy dispersions display even stronger mass renormalization. Using an effective tight banding model, we fitted the band structure and the FSs to obtain band parameters reliable for theoretical modeling and calculation of physical quantities.