Abstract
The deliberate insertion of magnetic Mn dopants in the Fe sites of the optimally doped iron-based superconductor can modify in a controlled way its electronic properties. The resulting phase diagram was investigated across a wide range of manganese contents () by means of muon-spin spectroscopy (), both in zero and in transverse fields, to probe the magnetic and the superconducting order, respectively. The pure superconducting phase (at ) is replaced by a crossover region at intermediate Mn values (), where superconductivity coexists with static magnetic order. After completely suppressing superconductivity for , a further increase in Mn content reinforces the natural tendency towards antiferromagnetic correlations among the magnetic Mn ions. The sharp drop of and the induced magnetic order in the presence of magnetic disorder/dopants, such as Mn, are both consistent with a recent theoretical model of unconventional superconductors (M. N. Gastiasoro et al., Phys. Rev. Lett. 117, 257002 (2016)), which includes correlation-enhanced RKKY couplings between the impurity moments.
6 More- Received 3 September 2016
- Revised 14 November 2016
DOI:https://doi.org/10.1103/PhysRevB.94.214517
©2016 American Physical Society