title: The metal-insulator transition in Fe(1.01-x)Cu(x)Se.
abstract: Iron selenide, Fe(1.01)Se, the layered parent compound of the recently discovered superconducting arsenide family, has previously been shown to be non-magnetic and superconducting with a critical temperature of 8 K. Here we show that copper can be substituted at the iron site in Fe(1.01)Se up to a solubility limit of 20-30%, after which a first-order transition to the three-dimensional CuFeSe(2) structure type is observed. As little as 1.5% copper is sufficient to suppress the superconductivity, and 4% drives the system through a metal-insulator transition. A local magnetic moment is introduced, which maximizes near 12% doping, where a spin-glass transition near 15 K is observed.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Williams
authors.forename: T M
authors.initials: TM
authors.lastname: McQueen
authors.forename: V
authors.initials: V
authors.lastname: Ksenofontov
authors.forename: C
authors.initials: C
authors.lastname: Felser
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava