Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rare earth size dependence on structural, electronic and magnetic
  properties of R2NiMnO6 double perovskites   Rare earth Manganite Nickelite double perovskites are prepared by solgel
assisted combustion route, where, R varies from La, Pr, Nd, Sm, Gd, Tb, Dy, Y,
and Ho. The samples have been systematically investigated using powder xray
diffraction, Raman spectroscopy, ultraviolet visible spectroscopy,
magnetization, and synchrotron based xray absorption spectroscopy measurements.
All compounds in the family crystallize in the monoclinic structure and the
monoclinic distortion enhances with decreasing trivalent rare earth radii. The
magnetic ordering temperature, Tc, decreases from 270 K for La to 80 K for Ho
samples as the rare earth radii decrease from 0.116nm for La to 0.102nm in case
of Ho. An additional anomaly is observed in samples containing Nd, Sm, Tb, and
Dy at lower temperatures, which originates from the 3d to 4f coupling between
Mn and Ni and Nd, Sm, Tb and Dy magnetic moments. Further, high saturation
magnetization is achieved for all samples indicating that they are atomically
ordered and have less anti site disorders. Upon decreasing the size of rare
earth ions, the local structure shows an expansion of NiO6 octahedra and almost
unchanged MnO6 octahedra. Xray absorption near edge spectroscopy reveals that
majority of Ni and Mn ions are in positive 2 and positive 4 valence states in
all the samples. Raman spectra of RNMO show a softening of phonon modes
resulting in the elongation of Ni to O and Mn to O bond lengths. Finally, a
correlation between lattice parameters, structural distortion, octahedral
tilting, superexchange angle, and electronic band gap, Curie temperature, and
the rare earth ionic radius is established.

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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: eess
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: physics
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The categories of this paper are: hep-ph