Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Upper critical field, superconducting energy gaps, and Seebeck
  coefficient in La0.8Th0.2OFeAs   We report the synthesis and characterization of a new electron-doped
La-oxypnictide superconductor by partial substitution of lanthanum by thorium.
The superconducting transition temperature at about 30.3 K was observed in
La0.8Th0.2OFeAs which is the highest in La-based oxypnictide superconductors
synthesized at ambient pressure. We find that the decrease in lattice
parameters with Th doping in LaOFeAs is more drastic as compared to that
obtained by high pressure (6 GPa) synthesis of oxygen deficient LaOFeAs. The
resistivity and magnetic susceptibility measurements yield an upper critical
field Hc2 (0) of 47 T. Partial substitution of Th in place of La induces
electron doping as evidenced by negative Seebeck coefficient. The temperature
dependent magnetic penetration depth data provides strong evidence for a
nodeless low energy gap of 1.4 meV.

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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: hep-lat
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
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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: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: astro-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs