Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron powder diffraction investigation of the structural and magnetic
  properties of (La1-yYy)FeAsO   The structural, magnetic and resistive properties of (La1-yYy)FeAsO compounds
(y = 0.10, 0.20, 0.30) have been investigated by means of X-ray and neutron
powder diffraction as well as by resistivity measurements. The temperatures at
which the structural transition from tetragonal to orthorhombic and the
magnetic ordering take place progressively reduce by similar amounts with
increasing Y substitution on account of the progressive chemical pressure
increase. We propose that the structural transition could be originated by a
cooperative Jahn-Teller distortion involving the alignment of the fully
occupied Fe 3d(z2) orbitals in the Fe plane along the y axis, leading to the
branching of the cell parameters a and b. The magnetic structure develops after
the occurrence of the structural transition, but before its completion.

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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
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The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
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The categories of this paper are: eess
1
The categories of this paper are: cs
16
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: astro-ph
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph