Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instability of Magnons in Two-dimensional Antiferromagnet at High
  Magnetic Fields   Spin dynamics of the square lattice Heisenberg antiferromagnet, \BaMnGeO, is
studied by a combination of bulk measurements, neutron diffraction, and
inelastic neutron scattering techniques. Easy plane type antiferromagnetic
order is identified at $T \le 4.0$ K. The exchange interactions are estimated
as $J_1$ = 27.8(3)${\mu}$eV and $J_2$ = 1.0(1) ${\mu}$eV, and the saturation
field $H_{\rm C}$ is 9.75 T. Magnetic excitation measurements with high
experimental resolution setup by triple axis neutron spectrometer reveals the
instability of one magnon excitation in the field range of $0.7H_{\rm C}
\lesssim H \lesssim 0.85H_{\rm C}$.

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The categories of this paper are: math-ph
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The categories of this paper are: physics
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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: funct-an
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: eess