Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Efficient Electrical Spin Injection from a Magnetic Metal / Tunnel
  Barrier Contact into a Semiconductor
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
2
The categories of this paper are: math
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph