Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconducting dome and microstructure properties of Rb0.8Fe1.6+xSe2
  superconductors   High quality Rb0.8Fe1.6+xSe2 single crystals are grown by a one step melting
growth method. Superconductivity has been observed in all samples with x more
than 0.05 and the maximum critical temperature Tc~32 K has been obtained in
samples with x from 0.1 to 0.2 from electronic resistivity measurement. A
superconducting dome in the electronic phase diagram of Tc as a function of Fe
content has been observed for the first time in this AxFeySe2 (A=K,Rb)
superconducting system. Two coexisting phases with structural modulation
vectors of q1=1/5 [3a*+b*] and q2=1/2[a*+b*] have been observed in all
superconducting samples by TEM observations. Moreover, phase separation in the
superconducting crystals, which can be recognized as micro-stripes in the ab
plane, are found to be highly dependent on the Fe content.

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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg