Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of Two-Step Magnetic Ordering Phenomena in a Geometrically
  Frustrated Heisenberg Pyrochlore Antiferromagnet with Long Range Dipolar
  Interactions   A model for a Heisenberg antiferromagnet on a pyrochlore lattice with
exchange and dipole-dipole interactions is studied via mean-field theory. In
treating the dipoles by use of the Ewald method, a soft (critical) mode with a
unique ordering wave vector is selected for all strengths of the dipole-dipole
coupling. For weak dipoles a partially ordered, three sublattice spin structure
(P state), with q_{ord}= (1/2 1/2 1/2), is selected. A fully ordered, four
sublattice spin structure (F state), with q = (000), competes with the P state
and becomes the stable structure as the temperature is reduced. Our results are
compared against other theoretical calculations and connections to recent
experimental results for Gd2Ti2O7 are discussed.

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The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: stat