Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple superconducting gap and anisotropic spin fluctuations in iron
  arsenides: Comparison with nickel analog   We present extensive 75As NMR and NQR data on the superconducting arsenides
PrFeAs0.89F0.11 (Tc=45 K), LaFeAsO0.92F0.08 (Tc=27 K), LiFeAs (Tc = 17 K) and
Ba0.72K0.28Fe2As2 (Tc = 31.5 K) single crystal, and compare with the nickel
analog LaNiAsO0.9F0.1 (Tc=4.0 K) . In contrast to LaNiAsO0.9F0.1 where the
superconducting gap is shown to be isotropic, the spin lattice relaxation rate
1/T1 in the Fe-arsenides decreases below Tc with no coherence peak and shows a
step-wise variation at low temperatures. The Knight shift decreases below Tc
and shows a step-wise T variation as well. These results indicate spinsinglet
superconductivity with multiple gaps in the Fe-arsenides. The Fe
antiferromagnetic spin fluctuations are anisotropic and weaker compared to
underdoped copper-oxides or cobalt-oxide superconductors, while there is no
significant electron correlations in LaNiAsO0.9F0.1. We will discuss the
implications of these results and highlight the importance of the Fermi surface
topology.

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The categories of this paper are: q-fin
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph