Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Skyrmion crystals in centrosymmetric triangular magnets under hexagonal
  and trigonal single-ion anisotropy   We theoretically report an instability toward a skyrmion crystal in
centrosymmetric magnets under hexagonal and trigonal single-ion anisotropy. The
results are obtained for a minimal spin model with a crystal-dependent
single-ion anisotropy on a triangular lattice by performing simulated
annealing. By constructing magnetic phase diagrams in the presence of six
different types of single-ion anisotropy while changing the amplitudes of
external magnetic field and single-ion anisotropy in a systematic way, we find
that the hexagonal and trigonal single-ion anisotropy becomes a source of the
skyrmion crystal depending on the magnetic-field direction. We show that the
skyrmion crystal is stabilized by the uniaxial-type or trigonal-type single-ion
anisotropy under the out-of-plane magnetic field, while it is stabilized by the
hexagonal-type inplane single-ion anisotropy under the inplane magnetic field.
We also find various multiple-$Q$ spin states depending on the types of the
single-ion anisotropy.

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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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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: math
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The categories of this paper are: comp-gas
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
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The categories of this paper are: stat