Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2
  wires and bulks   The K- and Co-doped BaFe2As2 (Ba-122) superconducting compounds are
potentially useful for applications because they have upper critical fields
(Hc2) of well over 50 T, Hc2 anisotropy Gamma < 2, and thin film critical
current densities exceeding 1 MAcm-2 at 4.2 K. However, thin-film bicrystals of
Co-doped Ba-122 clearly exhibit weak link behavior for [001] tilt
misorientations of more than about 5 degrees, suggesting that textured
substrates would be needed for applications, as in the cuprates. Here we
present a contrary and very much more positive result in which untextured
polycrystalline (Ba0.6K0.4)Fe2As2 bulks and round wires with high grain
boundary density have transport critical current densities well over 0.1 MAcm-2
(SF, 4.2 K), more than 10 times higher than that of any other ferropnictide
wire. The enhanced grain connectivity is ascribed to their much improved phase
purity and to the enhanced vortex stiffness of this low-anisotropy compound
(Gamma ~ 1-2) compared to YBa2Cu3O7-x (Gamma ~ 5).

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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: math
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex