Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Direct observation of charge order and orbital glass state in
  multiferroic LuFe2O4
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn