Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anharmonic magnon excitations in noncollinear and charge-ordered
  RbFe$^{2+}$Fe$^{3+}$F$_6$   RbFe$^{2+}$Fe$^{3+}$F$_6$ is an example of a charge ordered antiferromagnet
where iron sites, with differing valences, are structurally separated into two
interpenetrating sublattices. The low temperature magnetically ordered
Fe$^{2+}$ ($S$=2) and Fe$^{3+}$ ($S$=5/2) moments form a noncollinear
orthogonal structure with the Fe$^{3+}$ site displaying a reduced static
ordered moment. Neutron spectroscopy on single crystals finds two distinct spin
wave branches with a dominant coupling along the Fe$^{3+}$ chain axis
($b$-axis). High resolution spectroscopic measurements find an intense energy
and momentum broadened magnetic band of scattering bracketing a momentum-energy
region where two magnon processes are kinematically allowed. These anharmonic
excitations are enhanced in this non collinear magnet owing to the orthogonal
spin arrangement.

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The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph