H. Ding et al 2008 EPL 83 47001 doi:10.1209/0295-5075/83/47001
H. Ding1, P. Richard2, K. Nakayama3, K. Sugawara3, T. Arakane3, Y. Sekiba3, A. Takayama3, S. Souma2, T. Sato3, T. Takahashi2,3, Z. Wang4, X. Dai1, Z. Fang1, G. F. Chen1, J. L. Luo1 and N. L. Wang1
Show affiliationsWe have performed a high-resolution angle-resolved photoelectron spectroscopy study on the newly discovered superconductor Ba0.6K0.4Fe2As2 (Tc=37 K). We have observed two superconducting gaps with different values: a large gap (Δ~12 meV) on the two small hole-like and electron-like Fermi surface (FS) sheets, and a small gap (~6 meV) on the large hole-like FS. Both gaps, closing simultaneously at the bulk transition temperature (Tc), are nodeless and nearly isotropic around their respective FS sheets. The isotropic pairing interactions are strongly orbital dependent, as the ratio 2Δ/kBTc switches from weak to strong coupling on different bands. The same and surprisingly large superconducting gap due to strong pairing on the two small FSs, which are connected by the (π, 0) spin-density-wave vector in the parent compound, strongly suggests that the pairing mechanism originates from the inter-band interactions between these two nested FS sheets.
Issue 4 (August 2008)
Received 3 July 2008, accepted for publication 7 July 2008
Published 14 July 2008
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