Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge density waves in Sr_14-xCa_xCu_24O_41: electron correlations vs.
  structural effects   We report inelastic light scattering experiments in the spin-chain and ladder
system Sr_14-xCa_xCu_24O_41. A depletion of an electronic background is
observed for 0 < x < 5 at low temperatures and with light polarization both
parallel to the leg and rung directions. This points to the formation of 2D
charge density wave in the ladders. Furthermore, the Ca-substitution dependence
of the 305- and 249-cm-1 modes, sensitive to the lattice modulations of the
respective chain and ladder system, suggests that the charge dynamics in the
ladders is strongly influenced by the structural incommensurability.

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The categories of this paper are: eess
28
The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th