Absence of superconductivity in the hole-doped Fe pnictide Ba(Fe1−xMnx)2As2: Photoemission and x-ray absorption spectroscopy studies

We have studied the electronic structure of Ba(Fe${}_{1-x}$Mn${}_x$)${}_2$As${}_2$ ($x=0.08$), which fails to become a superconductor in spite of the formal hole doping like Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$, 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 $L_3$ 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 3$d$ 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${}_{1-x}$Mn${}_x$)${}_2$As${}_2$ 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.