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