Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: KxFe2-ySe2 single crystals: Floating-zone growth, Transport and
  Structural properties   Single crystals of superconducting KxFe2-ySe2 have been grown with the
optical floating-zone technique under application of 8 bar of argon pressure.
We found that large and high quality single crystals with dimensions of
~\varnothing6 \times 10 mm could be obtained at the termination of the grown
ingot through quenching, while the remaining part of the ingot decomposed.
As-grown single crystals commonly represent an intergrowth of two sets of the
c-axis characterized by slightly different lattice constants. Single crystal of
K0.80Fe1.81Se2 shows a superconducting transition at Tc = 31.6 K, leading to a
near 100% expulsion of the external magnetic field in magnetization
measurements. On the other hand, neutron-diffraction data indicate that
superconductivity in the sample coexists with a iron-vacancy superstructure and
static antiferromagnetic order. The anisotropic ratio of the upper critical
field Hc2 for both H//c and H//ab configurations is \sim3.46.

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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: chem-ph