Abstract
In this paper, we report the results of detailed studies on Mn and Cu substitution to Fe site of , namely, and ( equals to 0.03–0.05 based on our neutron-diffraction refinements). The results show that with only Cu doping the compound becomes a Mott insulator. Detailed temperature-dependent structural analyses of these Mn- and Cu-substituted compounds show that the structural transition, which is associated with the changes in the building block tetrahedron, is essential to the occurrence of superconductivity in .
- Received 19 August 2009
DOI:https://doi.org/10.1103/PhysRevB.82.104502
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