NMR Study of Superconductivity and Spin Fluctuations in Hole-Doped Superconductor Ca1-xNaxFe2As2 (Tc=32 K)
MA Long1, ZHANG Jin-Shan2, WANG Du-Ming1, HE Jun-Bao1, XIA Tian-Long1, CHEN Gen-Fu1, YU Wei-Qiang1**
1Department of Physics, Renmin University of China, Beijing 100872 2School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206
NMR Study of Superconductivity and Spin Fluctuations in Hole-Doped Superconductor Ca1-xNaxFe2As2 (Tc=32 K)
MA Long1, ZHANG Jin-Shan2, WANG Du-Ming1, HE Jun-Bao1, XIA Tian-Long1, CHEN Gen-Fu1, YU Wei-Qiang1**
1Department of Physics, Renmin University of China, Beijing 100872 2School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206
Abstract：We report both 23Na and 75As nuclear magnetic resonance (NMR) studies on hole?doped Ca1-xNaxFe2As2 superconducting single crystals (x≈0.67) with the superconducting temperature Tc=32 K. Singlet superconductivity is suggested by a sharp drop of the Knight shift 75K below Tc. The spin-lattice relaxation rate 1/T1 does not show the Slichter–Hebel coherence peak, which suggests an unconventional pairing. The penetration depth is estimated to be 0.24 μm at temperature T=2 K. Here 1/75T1T shows an anisotropic behavior and a prominent low-temperature upturn , with 75T1 denoting the 75As spin-lattice relaxation time and T the temperature, which indicates strong low-energy antiferromagnetic spin fluctuations and supports a magnetic origin of superconductivity.
MA Long, ZHANG Jin-Shan, WANG Du-Ming, HE Jun-Bao, XIA Tian-Long, CHEN Gen-Fu, YU Wei-Qiang. NMR Study of Superconductivity and Spin Fluctuations in Hole-Doped Superconductor Ca1-xNaxFe2As2 (Tc=32 K)[J]. 中国物理快报, 2012, 29(6): 67402-067402.
MA Long, ZHANG Jin-Shan, WANG Du-Ming, HE Jun-Bao, XIA Tian-Long, CHEN Gen-Fu, YU Wei-Qiang. NMR Study of Superconductivity and Spin Fluctuations in Hole-Doped Superconductor Ca1-xNaxFe2As2 (Tc=32 K). Chin. Phys. Lett., 2012, 29(6): 67402-067402.
2012, Vol. 29 
