77Se NMR study of the pairing symmetry and the spin dynamics in K(y)Fe(2-x)Se2

Weiqiang Yu; L Ma; J B He; D M Wang; T-L Xia; G F Chen; Wei Bao

doi:10.1103/PhysRevLett.106.197001

77Se NMR study of the pairing symmetry and the spin dynamics in K(y)Fe(2-x)Se2

Phys Rev Lett. 2011 May 13;106(19):197001. doi: 10.1103/PhysRevLett.106.197001. Epub 2011 May 9.

Authors

Weiqiang Yu¹, L Ma, J B He, D M Wang, T-L Xia, G F Chen, Wei Bao

Affiliation

¹ Department of Physics, Renmin University of China, Beijing 100872, China. wqyu_phy@ruc.edu.cn

PMID: 21668191
DOI: 10.1103/PhysRevLett.106.197001

Abstract

We present a 77Se NMR study of the newly discovered iron selenide superconductor K(y)Fe(2-x)Se2, in which T(c) = 32 K. Below T(c), the Knight shift 77K drops sharply with temperature, providing strong evidence for singlet pairing. Above T(c), Korringa-type relaxation indicates Fermi-liquid behavior. Our experimental results set strict constraints on the nature of possible theories for the mechanism of high-T(c) superconductivity in this iron selenide system.