Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-pressure study of superconducting and non-superconducting single
  crystals of the same nominal composition Rb0.8Fe2Se2   Two single crystalline samples with the same nominal composition of
Rb0.8Fe2Se2 prepared via slightly different precursor routes under the same
thermal processing conditions were investigated at ambient and high pressures.
One sample was found superconducting with a Tc of ~31 K without the previously
reported resistivity-hump and the other was unexpectedly found to be a
narrow-gap semiconductor. While the high pressure data can be understood in
terms of pressure-induced variation in doping, the detailed doping effect on
superconductivity is yet to be determined.

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The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
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The categories of this paper are: atom-ph