Electron-hole asymmetry in the superconductivity of doped BaFe ₂As₂ seen via the rigid chemical-potential shift in photoemission

We have performed a systematic photoemission study of the chemical-potential shift as a function of carrier doping in a pnictide system based on BaFe₂As₂. The experimentally determined chemical-potential shift is consistent with the prediction of a rigid band shift picture by renormalized first-principle band calculations. This leads to an electron-hole asymmetry (EHA) in the Fermi surface (FS) nesting condition due to different effective masses for different FS sheets, which can be calculated from the Lindhard function of susceptibility. This built-in EHA, which matches well the observed asymmetric superconducting domes in the phase diagram, strongly supports FS quasinesting driven superconductivity in iron pnictides.