Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic structure and exotic exchange splitting in spin-density-wave
  states of BaFe$_2$As$_2$   The magnetic properties in the parent compounds are often intimately related
to the microscopic mechanism of superconductivity. Here we report the first
direct measurements on the electronic structure of a parent compound of the
newly discovered iron-based superconductor, BaFe$_2$As$_2$, which provides a
foundation for further studies. We show that the energy of the spin density
wave (SDW) in BaFe$_2$As$_2$ is lowered through exotic exchange splitting of
the band structure, rather than Fermi surface nesting of itinerant electrons.
This clearly demonstrates that a metallic SDW state could be solely induced by
interactions of local magnetic moments, resembling the nature of
antiferromagnetic order in cuprate parent compounds.

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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
2
The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci