title: Structural models of FeSe(x).
abstract: Two different structural models for non-stoichiometric FeSe(x) are examined and compared with soft x-ray spectroscopy findings for FeSe(x) (x = 0.85, 0.50). A structural model of tetragonal FeSe with excess interstitial Fe gives better agreement with experiment than a structural model of tetragonal FeSe with Se vacancies. This interstitial Fe increases the number of 3d states at the Fermi level. We find evidence that large non-stoichiometric ratios of Fe:Se, such as that of FeSe(0.50), yield clusters of pure Fe in the crystal structure.
authors.affiliation: Institute of Metal Physics, Russian Academy of Sciences-Ural Division, 620219 Yekaterinburg, Russia.
authors.forename: E Z
authors.initials: EZ
authors.lastname: Kurmaev
authors.forename: J A
authors.initials: JA
authors.lastname: McLeod
authors.forename: N A
authors.initials: NA
authors.lastname: Skorikov
authors.forename: L D
authors.initials: LD
authors.lastname: Finkelstein
authors.forename: A
authors.initials: A
authors.lastname: Moewes
authors.forename: M A
authors.initials: MA
authors.lastname: Korotin
authors.forename: Yu A
authors.initials: YA
authors.lastname: Izyumov
authors.forename: Y L
authors.initials: YL
authors.lastname: Xie
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: X H
authors.initials: XH
authors.lastname: Chen