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Discovery of orbital-selective Cooper pairing in FeSe
  • P. O. Sprau, Cornell University and Brookhaven National Laboratory
  • A. Kostin, Cornell University and Brookhaven National Laboratory
  • A. Kreisel, University of Copenhagen and Universität Leipzig
  • Anna E. Böhmer, Ames Laboratory
  • Valentin Taufour, Ames Laboratory and University of California, Davis
  • Paul C. Canfield, Iowa State University and Ames Laboratory
  • S. Mukherjee, Binghamton University--SUNY
  • P. J. Hirschfeld, University of Florida, Gainesville
  • B. M. Andersen, University of Copenhagen
  • J. C. Séamus Davis, Cornell University, Brookhaven National Laboratory, University of St Andrews, and University College Cork
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The superconductor iron selenide (FeSe) is of intense interest owing to its unusual nonmagnetic nematic state and potential for high-temperature superconductivity. But its Cooper pairing mechanism has not been determined. We used Bogoliubov quasiparticle interference imaging to determine the Fermi surface geometry of the electronic bands surrounding the Γ = (0, 0) and X = (π/aFe, 0) points of FeSe and to measure the corresponding superconducting energy gaps. We show that both gaps are extremely anisotropic but nodeless and that they exhibit gap maxima oriented orthogonally in momentum space. Moreover, by implementing a novel technique, we demonstrate that these gaps have opposite sign with respect to each other. This complex gap configuration reveals the existence of orbital-selective Cooper pairing that, in FeSe, is based preferentially on electrons from the dyz orbitals of the iron atoms.


This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published as Sprau, Peter O., Andrey Kostin, Andreas Kreisel, Anna E. Böhmer, Valentin Taufour, Paul C. Canfield, Shantanu Mukherjee, Peter J. Hirschfeld, Brian M. Andersen, and J.C. Séamus Davis. "Discovery of orbital-selective Cooper pairing in FeSe." Science 357, no. 6346 (2017): 75-80. DOI: 10.1126/science.aal1575.

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P. O. Sprau, A. Kostin, A. Kreisel, Anna E. Böhmer, et al.. "Discovery of orbital-selective Cooper pairing in FeSe" Science Vol. 357 Iss. 6346 (2017) p. 75 - 80
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