Two superconducting gaps in LaFeAsO0.92F0.08 revealed by 75As nuclear quadrupole resonance

被引：77

作者：

Kawasaki, S. ^{[1
]}

Shimada, K. ^{[1
]}

Chen, G. F. ^{[2
]}

Luo, J. L. ^{[2
]}

Wang, N. L. ^{[2
]}

Zheng, Guo-qing ^{[1
]}

机构：

[1] Okayama Univ, Dept Phys, Okayama 7008530, Japan

[2] Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China

来源：

PHYSICAL REVIEW B | 2008年 / 78卷 / 22期

关键词：

d-wave superconductivity; fluctuations in superconductors; high-temperature superconductors; iron compounds; lanthanum compounds; nuclear quadrupole resonance; nuclear spin-lattice relaxation; superconducting energy gap; superconducting transition temperature;

D O I：

10.1103/PhysRevB.78.220506

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We report As-75 nuclear quadrupole resonance studies on superconducting oxypnictide LaFeAsO0.92F0.08 (T-c=23 K). The temperature dependence of the spin-lattice relaxation rate (1/T-1) decreases below T-c without a coherence (Hebel-Slichter) peak and shows a temperature dependence that is not simple power law nor exponential. We show that the result can be understood in terms of two superconducting gaps of either d- or +/- s-wave symmetry, with the larger gap Delta(1)similar to 4k(B)T(c) and the smaller one Delta(2)similar to 1.5k(B)T(c). Our result suggests that the multiple-gap feature is universal in the oxypnictide superconductors, which is probably associated with the multiple electronic band structures in this class of materials. We also find that 1/T1T above T-c increases with decreasing temperature, which suggests weak magnetic fluctuations in the normal state.

引用

页数：4

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