Spin-singlet superconductivity with multiple gaps in PrFeAsO0.89F0.11K. Matano1, Z. A. Ren2, X. L. Dong2, L. L. Sun2, Z. X. Zhao2 and Guo-qing Zheng1
1 Department of Physics, Okayama University - Okayama 700-8530, Japan
2 Institute of Physics, Chinese Academy of Sciences - Beijing 100190, China
received 13 June 2008; accepted in final form 15 July 2008; published September 2008
published online 30 July 2008
We report 75As and 19F NMR studies on the superconducting properties of the newly discovered compound PrFeAsO0.89F0.11 (Tc = 45 K). The Knight shift in the direction of -plane decreases below Tc to almost zero, which indicates spin-singlet pairing. The temperature dependencies of both the Knight shift and the spin lattice relaxation rate indicate that there are two gaps opening below Tc, with nodes in the gap function.
74.20.Rp - Pairing symmetries (other than s-wave).
74.25.Nf - Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.).
74.70.Ad - Metals; alloys and binary compounds (including A15, MgB2, etc.).
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