Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple Quantum Oscillations in the de Haas van Alphen Spectra of the
  Underdoped High Temperature Superconductor YBa_2Cu_3O_6.5   By improving the experimental conditions and extensive data accumulation, we
have achieved very high-precision in the measurements of the de Haas-van Alphen
effect in the underdoped high-temperature superconductor
YBa$_{2}$Cu$_{3}$O$_{6.5}$. We find that the main oscillation, so far believed
to be single-frequency, is composed of three closely spaced frequencies. We
attribute this to bilayer splitting and warping of a single quasi-2D Fermi
surface, indicating that \emph{c}-axis coherence is restored at low temperature
in underdoped cuprates. Our results do not support the existence of a larger
frequency of the order of 1650 T reported recently in the same compound [S.E.
Sebastian {\it et al}., Nature {\bf 454}, 200 (2008)].

25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
9
The categories of this paper are: nlin
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The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
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The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: stat