Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic order and spin-waves in the quasi-1D S=1/2 antiferromagnet
  ${\bf BaCu_{2}Si_{2}O_{7}}$   Elastic and inelastic neutron scattering were used to study the ordered phase
of the quasi-one-dimensional spin-1/2 antiferromagnet ${\rm
BaCu_{2}Si_{2}O_{7}}$. The previously proposed model for the low-temperature
magnetic structure was confirmed. Spin wave dispersion along several
reciprocal-space directions was measured and inter-chain, as well as in-chain
exchange constants were determined. A small gap in the spin wave spectrum was
observed and attributed to magnetic anisotropy effects. The results are
discussed in comparison with existing theories for weakly-coupled quantum spin
chain antiferromagnets.

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The categories of this paper are: math
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
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The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex