Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Electromagnetic spin polarization on the surface of topological
  insulator
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga