Coexistence of multiple charge-density waves and superconductivity in SrPt2As2 revealed by 75As-NMR/NQR and 195Pt-NMR
Coexistence of multiple charge-density waves and superconductivity in SrPt2As2 revealed by 75As-NMR/NQR and 195Pt-NMR
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DOI：
10.1103/physrevb.91.060510
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发表时间：
2015-02-27
影响因子：
3.7
通讯作者：
Zheng, Guo-Qing
中科院分区：
文献类型：
--
作者：
Kawasaki, Shinji;Tani, Yoshihiko;Zheng, Guo-Qing
本文用As-75核磁共振（NMR）和As-75核四极共振（NQR）及Pt-195核磁共振（NMR）研究了具有CaBe_2Ge_2型结构的砷化物超导体SrPt_2As_2（Tc = 5.2K）的电荷密度波（CDW）级与超导电性的关系。在高温下，As~（75）NMR谱和核自旋弛豫速率（1/T~（-1））揭示了两个不同的CDW级，一个在T-CDW（As（1））= 410 K以下的As-Pt-As层中实现，另一个在T-CDW（As（2））= 255 K以下的Pt-As-Pt层中实现。用As-75-NQR测得的1/T-1在Tc以下有一个明显的Hebel-Slichter峰，在Tc以下呈指数下降。与此同时，Pt-195的骑士位移降低到低于T-c。我们的研究结果表明，在SrPt2As2的超导性是在自旋单重态的s波间隙，并在两个不同的CDW顺序在不同的层是强大的。
The relationship between charge-density wave (CDW) orders and superconductivity in arsenide superconductor SrPt2As2 with T-c = 5.2K which crystallizes in the CaBe2Ge2-type structure was studied by As-75 nuclear magnetic resonance (NMR) measurements up to 520 K, and As-75 nuclear quadrupole resonance (NQR) and Pt-195-NMR measurements down to 1.5 K. At high temperature, As-75-NMR spectrum and nuclear-spin-relaxation rate (1/T-1) have revealed two distinct CDW orders, one realized in the As-Pt-As layer below T-CDW(As(1)) = 410 K and the other in the Pt-As-Pt layer below T-CDW(As(2)) = 255 K. The 1/T-1 measured by As-75-NQR shows a clear Hebel-Slichter peak just below Tc and decreases exponentially well below T-c. Concomitantly, Pt-195 Knight shift decreases below T-c. Our results indicate that superconductivity in SrPt2As2 is in the spin-singlet state with an s-wave gap and is robust under the two distinct CDW orders in different layers.