Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $T_c$ Dependence of Energy Gap and Asymmetry of Coherence Peaks in
  NdBa$_2$Cu$_3$O$_{7-\delta}$   We report here the results of scanning tunneling spectroscopic experiments
performed on hole doped NdBa$_2$Cu$_3$O$_{7-\delta}$ single crystals of $T_c$
values of 76 K, 93.5 K and 95.5 K. The energy gaps are observed to be
increasing with decreasing $T_c$ values. The coherence peaks are asymmetric
with the peaks at the filled states being larger than those at the empty ones.
The asymmetry increases with decreasing $T_c$. The observed asymmetry and its
$T_c$ dependence can be explained by considering the Mott insulating nature of
the material at the undoped state.

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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph