Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Infrared spectrum and its implications for the electronic structure of
  the semiconducting iron selenide K$_{0.83}$Fe$_{1.53}$Se$_2$   We report an infrared spectroscopy study on K$_{0.83}$Fe$_{1.53}$Se$_2$, a
semiconducting parent compound of the new iron-selenide system. The major
spectral features are found to be distinctly different from all other Fe-based
superconducting systems. Our measurement revealed two peculiar spectral
structures: a double peak structure between 4000-6000 cm$^{-1}$ and abundant
phonon modes much more than those expected for a 122 structure. We elaborate
that those features could be naturally explained from the blocked
antiferromagnetism due to the presence of Fe vacancy ordering as determined by
recent neutron diffraction experiments. The double peaks reflect the
coexistence of ferromagnetic and antiferromagnetic couplings between the
neighboring Fe sites.

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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
2
The categories of this paper are: math