Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mid-infrared absorption in YBa2Cu3O6: Failure of spin-wave theory in
  undoped cuprates?   The optical conductivity sigma (omega) of undoped YBa2Cu3O6 is studied in
detail in the mid-infrared range. Substitutions on all but the Ba site are used
to identify the prominent absorption processes at 2800 and 3800 cm^-1.
Experimental evidence for bimagnon-plus-phonon absorption is collected. A more
critical analysis of the lineshape and the spectral weight reveals the limits
of this approach. Although phonon-2-magnon multiple scattering seems to
reproduce the lineshape, the necessary coupling is unrealistically large. The
strong increase of high frequency spectral weight with increasing temperature
makes the failure of spin-wave theory even more evident.

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The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
1
The categories of this paper are: cs
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The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th