Superconducting gap symmetry of Ba0.6K0.4Fe 2As2 studied by angle-resolved photoemission spectroscopy

K. Nakayama, T. Sato, P. Richard, Y. M. Xu, Y. Sekiba, S. Souma, G. F. Chen, J. L. Luo, N. L. Wang, H. Ding, T. Takahashi

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We have performed high-resolution angle-resolved photoemission spectroscopy on the optimally doped Ba0.6K0.4Fe2As 2 compound and determined the accurate momentum dependence of the superconducting (SC) gap in four Fermi-surface sheets including a newly discovered outer electron pocket at the M-point. The SC gap on this pocket is nearly isotropic and its magnitude is comparable (Δ∼11 meV) to that of the inner electron and hole pockets (∼12 meV), although it is substantially larger than that of the outer hole pocket (∼6 meV). The Fermi-surface dependence of the SC gap value is basically consistent with the Δ(k)=Δ0 cos kx cos ky formula expected for the extended s-wave symmetry. The observed finite deviation from the simple formula suggests the importance of multi-orbital effects.

Original languageEnglish
Article number67002
JournalEurophysics Letters
Issue number6
Publication statusPublished - 2009


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