Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ferro-type order of magneto-electric quadrupoles in the pseudo-gap phase
  of YBa2Cu3O6 + x unearthed by neutron diffraction   A theory that fully describes previously observed neutron Bragg spots
indicative of magnetic order in the pseudo-gap phase of YBa2Cu3O6 + x is
presented. Magnetic diffraction intensities, unveiled by polarization analysis,
are explained by parity-violating magnetic (magneto-electric) quadrupoles at
in-plane Cu sites arranged in a simple ferro-type motif. An absence of
conventional spin and orbital angular momentum dipoles in the theory is
compatible with the occurrence of superconductivity and strongly suggests,
moreover, that magneto-electric quadrupoles are the primary order-parameter in
the pseudo-gap phase.

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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: nucl-th
1
The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
3
The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: nlin