Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: M\"ossbauer studies of the peculiar magnetism in parent compounds of the
  iron-based superconductors   A review of the magnetism in the parent compounds of the iron-based
superconductors is given based on the transmission Moessbauer spectroscopy of
57Fe and 151Eu. It was found that the 3d magnetism is of the itinerant
character with varying admixture of the spin-polarized covalent bonds. For the
122 compounds a longitudinal spin density wave (SDW) develops. In the case of
the EuFe2As2 a divalent europium orders antiferromagnetically at much lower
temperature as compared to the onset of SDW. These two magnetic systems remain
almost uncoupled one to another. For the non-stoichiometric Fe(1+x)Te parent of
the 11 family one has a transversal SDW and magnetic order of the interstitial
iron with relatively high and localized magnetic moments. These two systems are
strongly coupled one to another. For the grand parent of the iron-based
superconductors FeAs one observes two mutually orthogonal phase-related
transversal SDW on the iron sites. There are two sets of such spin arrangements
due to two crystallographic iron sites. The FeAs exhibits the highest covalency
among compounds studied, but it has still a metallic character.

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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
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The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int