Evidence for a cos (4φ) modulation of the superconducting energy gap of optimally doped FeTe0.6Se0.4 single crystals using laser angle-resolved photoemission spectroscopy

K. Okazaki, Y. Ito, Y. Ota, Y. Kotani, T. Shimojima, T. Kiss, S. Watanabe, C. T. Chen, S. Niitaka, T. Hanaguri, H. Takagi, A. Chainani, S. Shin

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Abstract

We study the superconducting-gap anisotropy of the Γ-centered hole Fermi surface in optimally doped FeTe0.6Se0.4 (T c=14.5 K), using laser-excited angle-resolved photoemission spectroscopy. We observe sharp superconducting (SC) coherence peaks at T=2.5 K. In contrast to earlier angle-resolved photoemission spectroscopy studies but consistent with thermodynamic results, the momentum dependence shows a cos (4φ) modulation of the SC-gap anisotropy. The observed SC-gap anisotropy strongly indicates that the pairing interaction is not a conventional phonon-mediated isotropic one. Instead, the results suggest the importance of second-nearest-neighbor electronic interactions between the iron sites in the framework of s±-wave superconductivity.

Original languageEnglish
Article number237011
JournalPhysical review letters
Volume109
Issue number23
DOIs
Publication statusPublished - 2012 Dec 6

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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