Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Functional Mn--Mg$_k$ cation complexes in GaN featured by Raman
  spectroscopy
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th