Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photoinduced Domain Pattern Transformation in Ferroelectric/Dielectric
  Superlattices   The nanodomain pattern in ferroelectric/dielectric superlattices transforms
to a uniform polarization state under above-bandgap optical excitation. X-ray
scattering reveals a disappearance of domain diffuse scattering and an
expansion of the lattice. The reappearance of the domain pattern occurs over a
period of seconds at room temperature, suggesting a transformation mechanism in
which charge carriers in long-lived trap states screen the depolarization
field. A Landau-Ginzburg-Devonshire model predicts changes in lattice parameter
and a critical carrier concentration for the transformation.

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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg