Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetoplasmon resonances in polycrystalline bismuth as seen via
  terahertz spectroscopy   We report the magnetic field-dependent far-infrared reflectivity of
polycrystalline bismuth. We observe four distinct absorptions that we attribute
to magnetoplasmon resonances, which are collective modes of an electron-hole
liquid in magnetic field and become optical and acoustic resonances of the
electron-hole system in the small-field limit. The acoustic mode is expected
only when the masses of distinct components are very different, which is the
case in bismuth. In a polycrystal, where the translational symmetry is broken,
a big shift of spectral weight to acoustic plasmon is possible. This enables us
to detect an associated plasma edge. Although the polycrystal sample has grains
of randomly distributed orientations, our reflectivity results can be explained
by invoking only two, clearly distinct, series of resonances. In the limit of
zero field, the optical modes of these two series converge onto plasma
frequencies measured in monocrystal along the main optical axes.

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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: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: eess