First-principles theory of electron-spin fluctuation coupling and superconducting instabilities in iron selenide

ORAL

Abstract

We present first-principles calculations of the coupling of quasiparticles to spin fluctuations in iron selenide and discuss which types of superconducting instabilities this coupling gives rise to. We find that strong antiferromagnetic stripe-phase spin fluctuations lead to large coupling constants for superconducting gaps with s$+$/- -symmetry, but these coupling constants are significantly reduced by other spin fluctuations with small wave vectors. An accurate description of this competition and an inclusion of band structure and Stoner parameter renormalization effects lead to a value of the coupling constant for an s$+$/- symmetric gap which can produce a superconducting transition temperature consistent with experimental measurements.

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Authors

  • Johannes Lischner

    UC Berkeley and Lawrence Berkeley National Lab

  • Timur Bazhirov

    UC Berkeley

  • Allan MacDonald

    University of Texas, Austin, University of Texas at Austin, UT Austin, Univ of Texas, Austin, Department of Physics, University of Texas at Austin

  • Marvin L. Cohen

    University of California at Berkeley, Lawrence Berkeley National Lab, UC Berkeley and Lawrence Berkeley National Lab, UC Berkeley, Lawrence Berkeley National Laboratory, UC Berkeley physics/ LBNL MSD

  • Steven G. Louie

    University of California at Berkeley, Lawrence Berkeley National Lab, University of California - Berkeley and Lawrence Berkeley National Lab, Department of Physics, University of California at Berkeley; Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Univ of California - Berkeley and Lawrence Berkeley National Lab, Department of Physics, UC Berkeley and Lawrence Berkeley National Lab, University of California, Berkeley and Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, UC Berkeley and Lawrence Berkeley National Lab, University of California at Berkeley and Lawrence Berkeley National Lab, Physics Department, UC Berkeley and Lawrence Berkeley National Lab, Department of Physics, University of California, Berkeley, and Materials Science Division, Lawrence Berkeley National Lab, Berkeley, CA 94720, USA, UC Berkeley physics/ LBNL MSD