title: Control of the competition between a magnetic phase and a superconducting phase in cobalt-doped and nickel-doped NaFeAs using electron count.
abstract: Using a combination of neutron, muon, and synchrotron techniques we show how the magnetic state in NaFeAs can be tuned into superconductivity by replacing Fe by either Co or Ni. The electron count is the dominant factor, since Ni doping has double the effect of Co doping for the same doping level. We follow the structural, magnetic, and superconducting properties as a function of doping to show how the superconducting state evolves, concluding that the addition of 0.1 electrons per Fe atom is sufficient to traverse the superconducting domain, and that magnetic order coexists with superconductivity at doping levels less than 0.025 electrons per Fe atom.
authors.affiliation: Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, United Kingdom.
authors.forename: Dinah R
authors.initials: DR
authors.lastname: Parker
authors.forename: Matthew J P
authors.initials: MJ
authors.lastname: Smith
authors.forename: Tom
authors.initials: T
authors.lastname: Lancaster
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Steele
authors.forename: Isabel
authors.initials: I
authors.lastname: Franke
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Baker
authors.forename: Francis L
authors.initials: FL
authors.lastname: Pratt
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pitcher
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blundell
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Clarke