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Title: Towards a quantitative description of tunneling conductance of superconductors: Application to LiFeAs

Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental results. The spin-fluctuation theory of electronic pairing, based on first-principles electronic structure calculations, makes predictions for the superconducting gap. Within the same framework, the surface wave functions may also be calculated, allowing, e.g., for detailed comparisons between theoretical results and measured scanning tunneling topographs and spectra. We present such a comparison between theory and experiment on the Fe-based superconductor LiFeAs. Our results for the homogeneous surface as well as impurity states are presented as a benchmark test of the theory. For the homogeneous system, we argue that the maxima of topographic image intensity may be located at positions above either the As or Li atoms, depending on tip height and the setpoint current of the measurement. We further report the experimental observation of transitions between As- and Li-registered lattices as functions of both tip height and setpoint bias, in agreement with this prediction. Next, we give a detailed comparison between the simulated scanning tunneling microscopy images of transition-metal defects with experiment. Finally, we discuss possible extensionsmore » of the current framework to obtain a theory with true predictive power for scanning tunneling microscopy in Fe-based systems.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [5] ;  [6] ;  [6] ;  [6] ;  [9] ;  [10]
  1. Univ. of Copenhagen (Denmark). The Niels Bohr Inst.; Univ. of Leipzig (Germany). Inst. for Theoretical Physics
  2. RWTH Aachen Univ. (Germany). Inst. of Inorganic Chemistry
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences, Computer Science and Mathematics Division
  4. Shanghai Jiao Tong Univ. (China). T.D. Lee Inst., Dept. of Physics and Astronomy
  5. Max Planck Inst. for Solid State Research, Stuttgart (Germany); Univ. of Saint Andrews, Scotland (United Kingdom). School of Physics and Astronomy
  6. Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Physics and Astronomy, Quantum Matter Inst.
  7. Univ. of Saint Andrews, Scotland (United Kingdom). School of Physics and Astronomy
  8. Max Planck Inst. for Solid State Research, Stuttgart (Germany)
  9. Univ. of Florida, Gainesville, FL (United States). Dept. of Physics
  10. Univ. of Copenhagen (Denmark). The Niels Bohr Inst.
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 1407502
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 22; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1393903
Alternate Identifier(s):
OSTI ID: 1338087