Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Single-layer metallicity and interface magnetism of epitaxial graphene
  on SiC(000$\bar{1}$)
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph