title: Nontrivial Role of Interlayer Cation States in Iron-Based Superconductors.
abstract: Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials. Based on this premise, one would also expect the large class of isostructural and isoelectronic iron germanide compounds to be good superconductors. As a matter of fact, they, however, superconduct at very low temperatures or not at all. In this work we establish that superconductivity in iron germanides is suppressed by strong ferromagnetic tendencies, which surprisingly do not originate from changes in bond angles or bond distances with respect to iron pnictides and chalcogenides, but are due to changes in the electronic structure in a wide range of energies happening upon substitution of atom species (As by Ge and the corresponding spacer cations). Our results indicate that superconductivity in iron-based materials may not always be fully understood based on d or d-p model Hamiltonians only.
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Guterding
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
authors.forename: Harald O
authors.initials: HO
authors.lastname: Jeschke
authors.affiliation: Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA.
authors.forename: I I
authors.initials: II
authors.lastname: Mazin
authors.affiliation: National Research Council/Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Glasbrenner
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Bascones
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
authors.forename: Roser
authors.initials: R
authors.lastname: Valentí