Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Incommensurate spin-density-wave antiferromagnetism in CeRu$_2$Al$_2$B   The newly discovered Ising-type ferromagnet CeRu$_2$Al$_2$B exhibits an
additional phase transition at $T_\textrm{N}$ = 14.2 K before entering the
ferromagnetic ground state at $T_\textrm{C}$ = 12.8 K. We clarify the nature of
this transition through high resolution neutron diffraction measurements. The
data reveal the presence of a longitudinal incommensurate spin-density wave
(SDW) in the temperature range of $T_\textrm{C}<T<T_\textrm{N}$. The
propagation vector ${\bf q} \sim (0,0,0.148)$ is nearly temperature independent
in this region and discontinuously locks into ${\bf q} = 0$ at $T_\textrm{C}$.
Mean-field calculations of an effective Ising model indicate that the modulated
SDW phase is stabilized by a strong competition between ferromagnetic and
antiferromagnetic exchange interactions. This makes CeRu$_2$Al$_2$B a
particularly attractive model system to study the global phase diagram of
ferromagnetic heavy-fermion metals under influence of magnetic frustration.

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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn