Strikingly dissimilar effect of Mn and Zn dopants imposed on local structural distortion of Ba0.5K0.5Fe2As2superconductor

Abstract

To clarify the contrasting impurity effects of Mn and Zn dopants on the critical temperature of optimally doped Ba0.5K0.5Fe2As2superconductors, extended X-ray absorption fine-structure spectroscopy was implemented at the Fe and AsK-edge. In Mn-doped compounds a gradual deviation of the symmetric FeAs4tetrahedron and weakening of the Fe—As bond was observed. Conversely, in Zn-doped compounds the perfect FeAs4tetrahedron is maintained and the Fe—As bond is rigid. The local structural details are consistent with the development of superconductivity in these two systems, suggesting a significant role played by the topology of the FeAs4tetrahedron and rigidness of the Fe—As bond in Mn/Zn-doped Ba0.5K0.5Fe2As2superconductors.