Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron Transport in Diborides: Observation of Superconductivity in
  ZrB2   We report on syntheses and electron transport properties of polycrystalline
samples of diborides (AB2) with different transition metals atoms (A=Zr,Nb,Ta).
The temperature dependence of resistivity, \rho(T), and ac susceptibility of
these samples reveal superconducting transition of ZrB2 with Tc=5.5 K, while
NbB2 and TaB2 have been observed nonsuperconducting up to 0.37 K. Hc2(T) is
linear in temperature below Tc, leading to a rather low Hc2(0)= 0.1 T. At T
close to Tc, Hc2(T) demonstrates a downward curvature. We conclude that these
diborides as well as MgB2 samples behaves like a simple metals in the normal
state with usual Bloch-Gr\"uneisen temperature dependence of resistivity and
with Debye temperatures: 280 K, 460 K and 440 K, for ZrB2, NbB2 and MgB2,
respectively, rather than T^2 and T^3 as previously reported for MgB2.

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The categories of this paper are: comp-gas
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
10
The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: plasm-ph