Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Influence of space charge on domain patterns and susceptibility in a
  rhombohedral ferroelectric film   The presence of a space charge region induces an internal electric field
within the charged region that, in a ferroelectric material, would rotate the
polarisations to align with the field. The strength of the induced field would
therefore determine the domain patterns and polarisation switching properties
of the material. Using a phase-field model, we investigate the effect of
charged layers in fully and partially depleted BiFeO$_3$ thin films in the
rhombohedral phase. While the domain pattern in a charge-free BiFeO$_3$ film
consists of only two polarisation variants, we observe complex patterns with
four coexisting variants that form within the charged layers at sufficiently
high induced fields. These variants form a head-to-head configuration with an
interface that is either wavy or planar depending on the internal field
strength, which is determined by the charge density as well as the thickness of
the charged layer. For depletion layers with sufficient thickness, there exists
a range of charge density values for which the interface is wavy, while at high
densities the interface becomes planar. We find that films with wavy interfaces
exhibit enhanced susceptibilities with reduced hystereses compared to the
charge-free film. The results of our work suggest that introducing space charge
regions by careful selection of dopant density and electrode materials can
engineer domain patterns that yield a higher response with a smaller
hysteresis.

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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
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The categories of this paper are: math
32
The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
9
The categories of this paper are: nlin