Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Commensurate and Incommensurate Spin Fluctuations in YBa_2Cu_3O_{6+y}   We present an interpretation of the recent neutron data on the commensurate
and incommensurate spin fluctuations found in YBa_2d$Cu_3O_{6+y} based on a
special configuration of the electronic dispersion and intervention from the
d_{x^2-y^2}-wave superconducting phase. The observed switch over between the
commensurate and incommensurate fluctuation spectra at the change of frequency
or temperature is naturally accounted within this scenario.

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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: econ