Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Natural van der Waals heterostructural single crystals with both
  magnetic and topological properties
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess