Doping dependence of competing pairing channels in ${\rm Ba_{1-x}K_xFe_2As_2}$

ORAL

Abstract

We study the doping dependence of competing pairing channels in the superconducting state of ${\rm Ba_{1-x}K_xFe_2As_2}$ for $0.22\le x \le 0.70$. Around optimal doping symmetry-resolved Raman spectra reveal the existence of two collective exciton-like Bardasis-Schrieffer modes in $B_{1g}$-symmetry below the gap edge. These modes correspond to two sub-leading pairing interactions of $d_{x^2-y^2}$ symmetry, which compete with the dominant $s$-wave interaction. The experimental doping dependence of the corresponding pairing strengths is compared with a functional renormalization group study and a spin-fluctuation based approach via the random-phase approximation. Both techniques yield good agreement with each other and the experiment. This provides evidence for repulsive spin-fluctuations to dominate the present system, not only generating the $s\pm$-wave ground state but also the BS modes.

*SPP\,1458 (DFG), BaCaTeC, TRR\,80, DOE

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Authors

  • Thomas Boehm

    • Walther Meissner Institut

  • Florian Kretzschmar

    • Walther Meissner Institut

  • Andreas Baum

    • Walther Meissner Institut

  • Michael Rehm

    • Walther Meissner Institut

  • Daniel Jost

    • Walther Meissner Institut

  • Ramez Hosseinian Ahangharnejhad

    • Walther Meissner Institut

  • Ronny Thomale

    • University of W\"urzburg
    • Univ of Wuerzburg
    • Department of Physics, University of Wuerzburg, Germany
    • Institut für Theoretische Physik, Universität Würzburg, Germany

  • Christian Platt

    • Stanford University

  • Thomas Maier

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

  • Werner Hanke

    • University of W\"urzburg

  • Brian Moritz

    • SLAC National Accelerator Laboratory
    • SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences
    • Stanford Institute for Material and Energy Sciences

  • Thomas Devereaux

    • Stanford Unviersity
    • Stanford Institute for Materials and Energy Sciences, Stanford University & SLAC
    • SLAC National Accelerator Laboratory
    • SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences
    • Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA
    • Stanford Univ
    • SLAC National Accelerator Laboratory/Stanford University
    • Stanford Institute for Material and Energy Sciences

  • Douglas Scalapino

    • University of California, Santa Barbara

  • Saurabh Maiti

    • University of Florida
    • Univeristy of Florida

  • Peter Hirschfeld

    • Department of Physics, University of Florida, Gainesville
    • University of Florida
    • Univ of Florida - Gainesville

  • Peter Adelmann

    • Karlsruher Institut f\"ur Technologie

  • Thomas Wolf

    • Karlsruher Institut f\"ur Technologie

  • Hai-Hu Wen

    • Nanjing University

  • Rudi Hackl

    • Walther Meissner Institut