Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Iron pnictides: Single crystal growth and effect of doping on
  structural, transport and magnetic properties   We demonstrate the preparation of large, free standing iron pnictide single
crystals with a size up to 20 x 10 x 1 mm3 using solvents in zirconia crucibles
under argon atmosphere. Transport and magnetic properties are investigated to
study the effect of potassium doping on the structural and superconducting
property of the compounds. The spin density wave (SDW) anomaly at Ts ~138 K in
BaFe2As2 single crystals from self-flux shifts to Ts ~85 K due to Sn solvent
growth. We show direct evidence for an incorporation of Sn on the Fe site. The
electrical resistivity data show a sharp superconducting transition temperature
Tc~38.5 K for the single crystal of Ba0.68K0.32Fe2As2. A nearly 100% shielding
fraction and bulk nature of the superconductivity for the single crystal were
confirmed by magnetic susceptibility data. A sharp transition Tc~25 K occurred
for the single crystal of Sr0.85K0.15Fe2As2. There is direct evidence for a
coexistence of the SDW and superconductivity in the low doping regime of
Sr1-xKxFe2As2 single crystals. Structural implications of the doping effects as
well as the coexistence of the two order parameters are discussed.

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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: math
34
The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: acc-phys