Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Suppressed Superconductivity of the Surface Conduction Layer in
  Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ Single Crystals Probed by {\it c}-Axis
  Tunneling Measurements   We fabricated small-size stacks on the surface of
Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ (BSCCO-2212) single crystals with the bulk
transition temperature $T_c$$\simeq$90 K, each containing a few intrinsic
Josephson junctions. Below a critical temperature $T_c'$ ($\ll$ $T_c$), we have
observed a weakened Josephson coupling between the CuO$_2$ superconducting
double layer at the crystal surface and the adjacent one located deeper inside
a stack. The quasiparticle branch in the $IV$ data of the weakened Josephson
junction (WJJ) fits well to the tunneling characteristics of a d-wave
superconductor($'$)/insulator/d-wave superconductor (D$'$ID) junction. Also,
the tunneling resistance in the range $T_c'$$<$$T$$<$$T_c$ agrees well with the
tunneling in a normal metal/insulator/d-wave superconductor (NID) junction. In
spite of the suppressed superconductivity at the surface layer the symmetry of
the order parameter appears to remain unaffected.

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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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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: funct-an
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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: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: math