Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orbital-selective metal-insulator transition and gap formation above Tc
  in superconducting Rb1-xFe2-ySe2   We report on a hierarchy of temperatures Tc < Tgap < Tmet in superconducting
Rb1-xFe2-ySe2 observed by THz spectroscopy. Above Tmet = 90 K the material
reveals semiconducting characteristics. Below Tmet a coherent metallic THz
response emerges. This metal-to-insulator type, orbital selective transition is
clearly indicated by an isosbestic point in the temperature dependence of the
optical conductivity and dielectric constant at THz-frequencies. At Tgap = 61 K
a gap opens in the THz regime and then the superconducting transition occurs at
Tc = 32 K. This sequence of temperatures seems to reflect a corresponding
hierarchy of the electronic correlations in the different bands.

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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex