Neutron scattering and gap structure in KFe$_2$Se$_2$

ORAL

Abstract

The structure of the superconducting gap in the alkali metal iron selenide KFe$_2$Se$_2$ remains controversial. Due to the absence of Fermi surface hole-pockets, the usual sign-changing $s^\pm$ state is unlikely and node-less $d$-wave as well as bonding-anti-bonding $s$-wave gap structures have been suggested. Here we use an RPA BCS approximation for a realistic 3D 10-orbital tight-binding model to calculate the neutron scattering response for different gap structures. We show that both $d$-wave and $s$-wave states are consistent with a neutron resonance in the superconducting state, and discuss possible ways to distinguish between the different gap structures.

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Authors

  • Thomas Maier

    • Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
    • Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6494, USA
    • Oak Ridge National Laboratory
    • ORNL

  • Andreas Kreisel

    • Department of Physics, University of Florida, Gainesville, FL 32611
    • Department of Physics, University of Florida, Gainesville, FL 32611, USA

  • Yan Wang

    • HI875049
    • Department of Physics, University of Florida, Gainesville, FL 32611
    • Department of Physics, University of Florida, Gainesville, FL 32611, USA

  • Peter Hirschfeld

    • Department of Physics, University of Florida, Gainesville, FL
    • Department of Physics, University of Florida, Gainesville, FL 32611
    • Department of Physics, University of Florida, Gainesville, FL 32611, USA
    • Unversity of Florida
    • Department of Physics, University of Florida

  • Douglas Scalapino

    • Department of Physics, University of California, Santa Barbara, CA 93106
    • UCSB
    • Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA