Absence of superconductivity in the hole-doped Fe pnictide Ba(Fe _1-xMn_x)₂As₂: Photoemission and x-ray absorption spectroscopy studies

We have studied the electronic structure of Ba(Fe_1-xMn _x)₂As₂ (x=0.08), which fails to become a superconductor in spite of the formal hole doping like Ba_1-xK _xFe₂As₂, with photoemission spectroscopy and x-ray absorption spectroscopy (XAS). With decreasing temperature, a transition from the paramagnetic phase to the antiferromagnetic phase was clearly observed by angle-resolved photoemission spectroscopy. XAS results indicated that the substituted Mn atoms form a strongly hybridized ground state. Resonance-photoemission spectra at the Mn L₃ edge revealed that the Mn 3d partial density of states is distributed over a wide energy range of 2-13 eV below the Fermi level (E_F), with little contribution around E _F. This indicates that the dopant Mn 3d states are localized in spite of the strong Mn 3d-As 4p hybridization and split into the occupied and unoccupied parts due to the on-site Coulomb and exchange interaction. The absence of superconductivity in Ba(Fe_1-xMn_x) ₂As₂ can thus be ascribed both to the absence of carrier doping in the FeAs plane and to the stabilization of the competing G-type antiferromagnetic order by the Mn impurities.