Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconducting properties of La-substituted Bi-2201 crystals   The superconducting gap Delta has been measured in Bi2Sr2-xLaxCuO6+d single
crystals in a wide range of temperatures 4.2 K < T < Tc by point-contact and
tunnelling spectroscopy for current in c-direction. The value of Delta(4.2 K)
was found to scale with the critical temperature Tc in the whole range of
doping levels with the ratio 2D/kTc = 12.5 +/- 2. The closing of the gap Ds at
T = Tc has been registered in the underdoped, optimally doped as well as in the
overdoped sam-ples.

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The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
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The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ