Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dzyaloshinskii--Moriya interaction: How to measure its sign in weak
  ferromagnetics?   Three experimental techniques sensitive to the sign of the
Dzyaloshinskii--Moriya interaction are discussed: neutron diffraction,
Moessbauer gamma-ray diffraction, and resonant x-ray scattering. Classical
examples of hematite (alpha-Fe2O3) and MnCO3 crystals are considered in detail

20
The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph