Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Josephson Plasma Resonance in Tl$_2$Ba$_2$CaCu$_2$O$_8$ in a Magnetic
  Field Measured using THz Spectroscopy   We report the first measurements of the $c$-axis Josephson Plasma Resonance
(JPR) in Tl$_2$Ba$_2$CaCu$_2$O$_8$ as a function of temperature with and
without a $c$-axis magnetic field using terahertz time-domain spectroscopy in
transmission. The JPR is sensitive to the alignment of pancake vortices along
the $c$-axis, and is observed to decrease when applying a magnetic field as
expected.

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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin