| Issue |
EPL
Volume 87, Number 2, July 2009
|
|
|---|---|---|
| Article Number | 27012 | |
| Number of page(s) | 6 | |
| Section | Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties | |
| DOI | https://doi.org/10.1209/0295-5075/87/27012 | |
| Published online | 18 August 2009 | |
Anisotropic spin fluctuations and multiple superconducting gaps in hole-doped Ba0.72K0.28Fe2As2: NMR in a single crystal
1
Department of Physics, Okayama University - Okayama 700-8530, Japan
2
Max Planck Institute - Heisenbergstrasse 1, D-70569 Stuttgart, Germany, EU
3
Institute of Physics, Chinese Academy of Sciences - Beijing 100190, China
Corresponding author: zheng@psun.phys.okayama-u.ac.jp
Received:
1
July
2009
Accepted:
17
July
2009
We report the 75As-NMR study on a single crystal of the hole-doped iron-pnictide superconductor Ba0.72K0.28Fe2As2 (Tc = 31.5 K). 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 
decreases below Tc with no coherence peak and shows a stepwise variation at low temperatures, which is indicative of multiple superconducting gaps, as in the electron-doped Pr(La)FeAsO
Fx. Furthermore, no evidence was obtained for a microscopic coexistence of a long-range magnetic order and superconductivity.
PACS: 74.20.Rp – Pairing symmetry (other than s-wave) / 74.25.Jb – Electronic structure / 74.25.Nf – Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.)
© EPLA, 2009
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