Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing Local Variations of Superconductivity on the Surface of
  Ba(Fe1-xCox)2As2 Single Crystals   The spatially resolved electrical transport properties have been studied on
the surface of optimally-doped superconducting Ba(Fe1-xCox)2As2 single crystal
by using a four-probe scanning tunneling microscopy. While some non-uniform
contrast appears near the edge of the cleaved crystal, the scanning electron
microscopy (SEM) reveals mostly uniform contrast. For the regions that showed
uniform SEM contrast, a sharp superconducting transition at TC = 22.1 K has
been observed with a transition width (delta)Tc = 0.2 K. In the non-uniform
contrast region, TC is found to vary between 19.6 and 22.2 K with (delta)Tc
from 0.3 to 3.2 K. The wavelength dispersive x-ray spectroscopy reveals that Co
concentration remains 7.72% in the uniform region, but changes between 7.38%
and 7.62% in the non-uniform region. Thus the variations of superconductivity
are associated with local compositional change.

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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
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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: ao-sci
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The categories of this paper are: econ
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ex
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The categories of this paper are: supr-con