Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strain and Magnetic Field Induced Spin-Structure Transitions in
  Multiferroic BiFeO3   The magnetic-field-dependent spin ordering of strained BiFeO3 films is
determined using nuclear resonant scattering and Raman spectroscopy. The
critical field required to destroy the cycloidal modulation of the Fe spins is
found to be significantly lower than in the bulk, with appealing implications
for field-controlled spintronic and magnonic devices.

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The categories of this paper are: acc-phys
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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: solv-int
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
2
The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph