Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of magnetic and crystal structures in the multiferroic
  FeTe2O5Br   Neutron diffraction and nuclear quadrupole resonance (NQR) measurements were
employed to investigate magnetic order in the non-ferroelectric phase preceding
the low-temperature multiferroic state in FeTe2O5Br. Refnement of the neutron
diffraction data and simulations of 79,81Br NQR spectra reveal that the
incommensurate magnetic ordering in the non-ferroelectric state comprises
amplitude-modulated magnetic moments, similarly as in the multiferroic state.
The two ordered states differ in the orientation of the magnetic moments and
phase shifts between modulation waves. Surprisingly, all symmetry restrictions
for the electric polarization are absent in both states. The different
ferroelectric responses of the two states are thus argued to arise from the
differences in the phase shifts between certain modulation waves, which cancel
out in the non-ferrolectric state.

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The categories of this paper are: nucl-th
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The categories of this paper are: math
7
The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
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The categories of this paper are: eess
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg