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

Guo Qing Zheng, K. Matano, S. 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 journalArticlepeer-review

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 1 2010

Keywords

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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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