Multiple superconducting gaps and anisotropic spin fluctuations in hole-doped and electron-doped iron-pnictides: NMR studies

Guo-Qing Zheng, Kazuaki Matano, Shinji Kawasaki, Z. Li, G. L. Sun, D. L. Sun, C. T. Lin, G. F. Chen, J. L. Luo, N. L. Wang, Z. A. Ren, Z. X. Zhao

Research output: Contribution to journalArticle

Abstract

We present extensive 75As-NMR data on the electron-doped pnictides PrFeAsO 0.89F 0.11 (T c = 45 K), LaFeAsO 0.92F 0.08 (T c = 23 K), and the hole-doped Ba 0.72K 0.28Fe 2As 2 (T c = 31.5 K) single crystal. We find that the Fe antiferromagnetic spin fluctuations are anisotropic and are weaker compared to underdoped copper-oxides or cobalt-oxide superconductors. The spin lattice relaxation rate 1/T 1 decreases below T c with no coherence peak and shows a step-wise variation at low temperatures. The Knight shift decreases below T c and shows a step-wise T variation as well. These results indicate spin-singlet superconductivity with multiple gaps.

Original languageEnglish
Pages (from-to)609-612
Number of pages4
JournalJournal of Superconductivity and Novel Magnetism
Volume23
Issue number5
DOIs
Publication statusPublished - Jul 2010

Fingerprint

Spin fluctuations
Oxide superconductors
Group 5A compounds
Spin-lattice relaxation
Copper oxides
Superconductivity
Cobalt
Iron
Nuclear magnetic resonance
Single crystals
iron
nuclear magnetic resonance
Electrons
electrons
cobalt oxides
copper oxides
spin-lattice relaxation
Temperature
superconductivity
single crystals

Keywords

  • Iron-pnictide
  • NMR
  • Spin fluctuations
  • Superconducting gap

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Multiple superconducting gaps and anisotropic spin fluctuations in hole-doped and electron-doped iron-pnictides : NMR studies. / Zheng, Guo-Qing; Matano, Kazuaki; Kawasaki, Shinji; Li, Z.; Sun, G. L.; Sun, D. L.; Lin, C. T.; Chen, G. F.; Luo, J. L.; Wang, N. L.; Ren, Z. A.; Zhao, Z. X.

In: Journal of Superconductivity and Novel Magnetism, Vol. 23, No. 5, 07.2010, p. 609-612.

Research output: Contribution to journalArticle

Zheng, Guo-Qing ; Matano, Kazuaki ; Kawasaki, Shinji ; Li, Z. ; Sun, G. L. ; Sun, D. L. ; Lin, C. T. ; Chen, G. F. ; Luo, J. L. ; Wang, N. L. ; Ren, Z. A. ; Zhao, Z. X. / Multiple superconducting gaps and anisotropic spin fluctuations in hole-doped and electron-doped iron-pnictides : NMR studies. In: Journal of Superconductivity and Novel Magnetism. 2010 ; Vol. 23, No. 5. pp. 609-612.
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AU - Zheng, Guo-Qing

AU - Matano, Kazuaki

AU - Kawasaki, Shinji

AU - Li, Z.

AU - Sun, G. L.

AU - Sun, D. L.

AU - Lin, C. T.

AU - Chen, G. F.

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AU - Ren, Z. A.

AU - Zhao, Z. X.

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AB - We present extensive 75As-NMR data on the electron-doped pnictides PrFeAsO 0.89F 0.11 (T c = 45 K), LaFeAsO 0.92F 0.08 (T c = 23 K), and the hole-doped Ba 0.72K 0.28Fe 2As 2 (T c = 31.5 K) single crystal. We find that the Fe antiferromagnetic spin fluctuations are anisotropic and are weaker compared to underdoped copper-oxides or cobalt-oxide superconductors. The spin lattice relaxation rate 1/T 1 decreases below T c with no coherence peak and shows a step-wise variation at low temperatures. The Knight shift decreases below T c and shows a step-wise T variation as well. These results indicate spin-singlet superconductivity with multiple gaps.

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KW - Spin fluctuations

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