Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron and orbital correlations in Ca_{2-x}Sr_{x}RuO_{4} probed by
  optical spectroscopy   The doping and temperature dependent optical conductivity spectra of the
quasi-two-dimensional Ca_{2-x}Sr_xRuO_4 (0.0=<x=<2.0) system were investigated.
In the Mott insulating state, two electron correlation-induced peaks were
observed around 1.0 and 1.9 eV, which could be understood in terms of the
3-orbital Hubbard model. The low frequency peak showed a shift toward higher
frequency as temperature was lowered, which indicated that electron-phonon
interactions play an important role in the orbital arrangements. From the
systematic analysis, it was suggested that the antiferro-orbital and the
ferro-orbital ordering states could coexist.

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The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
18
The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex