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arXiv · 1204.0631

NMR study of superconductivity and spin fluctuations in hole-doped superconductor Ca1-xNaxFe2As2 (Tc =32 K)

Long Ma·J. S. Zhang·D. M. Wang·J. B. He·T. -L. Xia·G. F. Chen·Weiqiang Yu
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Abstract

We report both 23Na and 75As NMR studies on hole-doped Ca1-xNaxFe2As2 superconducting single crystals (x\approx 0.67) with 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 T=2 K. 1/75T1T shows an anisotropic behavior and a prominent low-temperature upturn, which indicates strong low-energy antiferromagnetic spin fluctuations and supports a magnetic origin of superconductivity.

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Long Ma, J. S. Zhang, D. M. Wang, J. B. He, T. -L. Xia, G. F. Chen, Weiqiang Yu. 2012-04-03. NMR study of superconductivity and spin fluctuations in hole-doped superconductor Ca1-xNaxFe2As2 (Tc =32 K). https://doi.org/10.1088/0256-307x%2F29%2F6%2F067402

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