Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Epitaxial Ferromagnetic Nanoislands of Cubic GdN in Hexagonal GaN   Periodic structures of GdN particles encapsulated in a single crystalline GaN
matrix were prepared by plasma assisted molecular beam epitaxy. High resolution
X-ray diffractometery shows that GdN islands, with rock salt structure are
epitaxially oriented to the wurtzite GaN matrix. Scanning transmission electron
microscopy combined with in-situ reflection high energy electron diffraction
allows for the study of island formation dynamics, which occurs after 1.2
monolayers of GdN coverage. Magnetometry reveals two ferromagnetic phases, one
due to GdN particles with Curie temperature of 70K and a second, anomalous room
temperature phase.

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The categories of this paper are: stat
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg