title: Ferromagnetic Spin Fluctuation and Unconventional Superconductivity in Rb2Cr3As3 Revealed by 75As NMR and NQR.
abstract: We report (75)As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies on the superconductor Rb(2)Cr(3)As(3) with a quasi-one-dimensional crystal structure. Below T∼100  K, the spin-lattice relaxation rate (1/T(1)) divided by temperature, 1/T(1)T, increases upon cooling down to T(c)=4.8  K, showing a Curie-Weiss-like temperature dependence. The Knight shift also increases with decreasing temperature. These results suggest ferromagnetic spin fluctuation. In the superconducting state, 1/T(1) decreases rapidly below T(c) without a Hebel-Slichter peak, and follows a T(5) variation below T∼3  K, which points to unconventional superconductivity with point nodes in the gap function.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Physics and State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027, China.
authors.forename: Z T
authors.initials: ZT
authors.lastname: Tang
authors.affiliation: Department of Physics and State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027, China.|Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China.
authors.forename: G H
authors.initials: GH
authors.lastname: Cao
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Zheng