Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Layered superconductors as negative-refractive-index metamaterials   We analyze the use of layered superconductors as anisotropic metamaterials.
Layered superconductors can have a negative refraction index in a wide
frequency range for arbitrary incident angles. Indeed, low-Tc (s-wave)
superconductors allow to produce artificial heterostructures with low losses
for T<<Tc. However, the real part of their in-plane effective permittivity is
very large. Moreover, even at low temperatures, layered high-Tc superconductors
have a large in-plane normal conductivity, producing large losses (due to
d-wave symmetry). Therefore, it is difficult to enhance the evanescent modes in
either low-Tc or high-Tc superconductors.

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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn