Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Partial order from disorder in a classical pyrochlore antiferromagnet   We investigate theoretically the phase diagram of a classical Heisenberg
antiferromagnet on the pyrochlore lattice perturbed by a weak second-neighbor
interaction J_2. The huge ground state degeneracy of the nearest-neighbor
Heisenberg spins is lifted by J_2 and a magnetically ordered ground state sets
in upon approaching zero temperature. We have found a new, partially ordered
phase with collinear spins at finite temperatures for a ferromagnetic J_2. In
addition to a large nematic order parameter, this intermediate phase also
exhibits a layered structure and a bond order that breaks the sublattice
symmetry. Thermodynamic phase boundaries separating it from the fully
disordered and magnetically ordered states scale as 1.87 J_2 S^2 and 0.26 J_2
S^2 in the limit of small J_2. The phase transitions are discontinuous. We
analytically examine the local stability of the collinear state and obtain a
boundary T ~ J_2^2/J_1 in agreement with Monte Carlo simulations.

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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: math