Momentum dependence of the superconducting gap in NdFeAsO$_{1-x}$F$_x$ single crystals measured by angle resolved photoemission spectroscopy

ORAL

Abstract

We use angle resolved photoemission spectroscopy (ARPES) to study the momentum dependence of the superconducting gap in NdFeAsO$_{1-x}$F$_x$ single crystals. We find that the $\Gamma$ hole pocket is fully gapped below the superconducting transition temperature. The value of the superconducting gap is 15 $\pm$ 3 meV and its anisotropy around the hole pocket is smaller than 20$\%$ of this value. This is consistent with an isotropic or anisotropic s-wave symmetry of the order parameter or exotic d-wave symmetry with nodes located off the Fermi surface sheets. This is a significant departure from the situation in the cuprates, pointing to possibility that the superconductivity in the iron arsenic based system arises from a different mechanism.

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Authors

  • Takeshi Kondo

    • Ames Laboratory and Iowa State University
    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • A.F. Santander-Syro

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • O. Copie

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • Chang Liu

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • M.E. Tillman

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • J. Schmalian

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • S.L. Bud'ko

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • P.C. Canfield

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University

  • A.D. Kaminski

    • Ames Lab. and Dept. of Physics and Astronomy, Iowa State University