Impact of iron-site defects on superconductivity in LiFeAs

Shun Chi, Ramakrishna Aluru, Udai Raj Singh, Ruixing Liang, Walter N. Hardy, D. A. Bonn, A. Kreisel, Brian M. Andersen, R. Nelson, T. Berlijn, W. Ku, P. J. Hirschfeld, and Peter Wahl
Phys. Rev. B 94, 134515 – Published 19 October 2016

Abstract

In conventional s-wave superconductors, only magnetic impurities exhibit impurity bound states, whereas for an s± order parameter they can occur for both magnetic and nonmagnetic impurities. Impurity bound states in superconductors can thus provide important insight into the order parameter. Here, we present a combined experimental and theoretical study of native and engineered iron-site defects in LiFeAs. A detailed comparison of tunneling spectra measured on impurities with spin-fluctuation theory reveals a continuous evolution from negligible impurity-bound-state features for weaker scattering potential to clearly detectable states for somewhat stronger scattering potentials. All bound states for these intermediate strength potentials are pinned at or close to the gap edge of the smaller gap, a phenomenon that we explain and ascribe to multiorbital physics.

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  • Received 11 July 2016
  • Revised 10 September 2016

DOI:https://doi.org/10.1103/PhysRevB.94.134515

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shun Chi1,2, Ramakrishna Aluru3,4, Udai Raj Singh3, Ruixing Liang1,2, Walter N. Hardy1,2, D. A. Bonn1,2, A. Kreisel5,*, Brian M. Andersen5, R. Nelson6, T. Berlijn7,8, W. Ku9,10, P. J. Hirschfeld11, and Peter Wahl3,4,†

  • 1Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
  • 2Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
  • 3Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
  • 4SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom
  • 5Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
  • 6Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
  • 7Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 8Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 9CMPMSD, Brookhaven National Laboratory, Upton, New York 11973, USA
  • 10Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
  • 11Department of Physics, University of Florida, Gainesville, Florida 32611, USA

  • *kreisel@itp.uni-leipzig.de
  • wahl@st-andrews.ac.uk

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Issue

Vol. 94, Iss. 13 — 1 October 2016

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