Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collinear Spin-density-wave Order and Anisotropic Spin Fluctuations in
  the Frustrated $J_1$--$J_2$ Chain Magnet NaCuMoO$_4$(OH)   The phase diagram of the quasi-one-dimensional magnet NaCuMoO$_4$(OH) is
established through single-crystal NMR and heat-capacity measurements. The
$^{23}$Na and $^1$H NMR experiments indicate a spiral and a collinear
spin-density-wave (SDW) order below and above $B_c$ = 1.5-1.8 T, respectively.
Moreover, in the paramagnetic state above the SDW transition temperature, the
nuclear spin-lattice relaxation rate $1/T_1$ indicates anisotropic spin
fluctuations that have gapped excitations in the transverse spectrum but
gapless ones in the longitudinal spectrum. These static and dynamic properties
are well described by a theoretical model assuming quasi-one-dimensional chains
with competing ferromagnetic nearest-neighbor interactions $J_1$ and
antiferromagnetic next-nearest-neighbor interactions $J_2$ ($J_1$-$J_2$
chains). Because of the excellent crystal quality and good one dimensionality,
NaCuMoO$_4$(OH) is a promising compound to elucidate the unique physics of the
frustrated $J_1$-$J_2$ chain.

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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol