Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NMR evidence for two-step phase-separation in
  Nd_{1.85}Ce_{0.15}CuO_{4-delta}   By Cu NMR we studied the spin and charge structure in
Nd_{2-x}Ce_{x}CuO_{4-delta}. For x=0.15, starting from a superconducting
sample, the low temperature magnetic order in the sample reoxygenated under 1
bar oxygen at 900^0 C, reveals a peculiar modulation of the internal field,
indicative for a phase characterized by large charge droplets ('Blob'-phase).
By prolonged reoxygenation at 4 bar the blobs brake up and the spin structure
changes to that of an ordered antiferromagnet (AF). We conclude that the
superconductivity in the n-type systems competes with a genuine type I
Mott-insulating state.

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The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
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The categories of this paper are: stat
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg