Impact of iron-site defects on superconductivity in LiFeAs

ORAL

Abstract

In iron-based high temperature superconductors the symmetry of the order parameter still remains a controversial topic where for the same compound sign changing and non sign-changing order parameters have been proposed theoretically. Among the iron-based superconductors, LiFeAs takes a special role (together with FeSe) by being a stoichiometric superconductor, minimizing intrinsic scattering. Here, we study engineered iron-site defects in LiFeAs by low temperature scanning tunneling microscopy and spectroscopy (STM/STS). The tunneling spectra obtained on individual defects show signatures of impurity bound states[1]. A detailed comparison of the tunneling spectra measured on impurities with theoretical simulations [2] enables us to draw conclusions about the superconducting order parameter in LiFeAs. Studying Ni, Co, Mn impurities and native defects, we find a continuous evolution from negligible impurity bound states at the smaller gap edge to detectable states as the scattering potential increases. [1] R. Aluru, et al., PRB 94, 134515 (2016) [2] A. Kreisel, et al., arXiv:1610.00619

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Authors

  • R. Aluru

    • University of St Andrews

  • P. Wahl

    • SUPA, School of Physics and Astronomy, University of St Andrews, UK
    • University of St Andrews

  • S. Chi

    • University of British Columbia

  • R. Liang

    • University of British Columbia

  • Walter Hardy

    • University of British Columbia

  • Doug Bonn

    • Stewart Blusson Quantum Matter Institute and Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
    • University of British Columbia
    • UBC

  • Andreas Kreisel

    • University of Copenhagen
    • ITP, U. Leipzig, Germany

  • B. M. Andersen

    • Niels Bohr Institute
    • University of Copenhagen

  • U. R. Singh

    • Max-Planck-Institut fuer Festkoerperforschung

  • R. Nelson

    • Louisiana State University

  • T. Berlijn

    • Oak Ridge National Laboratory

  • W. Ku

    • Brookhaven National Laboratory, Shanghai Jiao Tong University

  • Peter Hirschfeld

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