Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Density of states in gapped superconductors with pairing-potential
  impurities   We study the density of states in disordered s-wave superconductors with a
small gap anisotropy. Disorder comes in the form of common nonmagnetic
scatterers and pairing-potential impurities, which interact with electrons via
an electric potential and a local distortion of the superconducting gap. A set
of equations for the quasiclassical Green functions is derived and solved.
Within one spin sector, pairing-potential impurities and weak spin-polarized
magnetic impurities have essentially the same effect on the density of states.
We show that if the gap is isotropic, an isolated impurity with suppressed
pairing supports an infinite number of Andreev states. With growing impurity
concentration, the energy-dependent density of states evolves from a sharp gap
edge with an impurity band below it to a smeared BCS singularity in the
so-called universal limit. If a gap anisotropy is present, the density of
states becomes sensitive to ordinary potential disorder, and the existence of
of Andreev states localized at pairing-potential impurities requires special
conditions. An unusual feature related to the anisotropy is a nonmonotonic
dependence of the gap edge smearing on impurity concentration.

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The categories of this paper are: astro-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas