Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Van der Waals Engineering of Ferromagnetic Semiconductor
  Heterostructures for Spin and Valleytronics
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas