Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bilayer artificial spin ice: magnetic force switching and basic
  thermodynamics   We study an artificial spin ice system consisting of two identical layers
separated by a height offset $h$. For small separation, the layers are shown to
attract each other, provided the whole system is in the ground state. Such an
attraction comes about by means of a power-law force that we compare to van der
Waals forces. When magnetic monopoles occur in one (or both) layers, the
scenario becomes even more interesting and these layers may also repel each
other. By tuning parameters like $h$ and monopole distance, switching between
attraction and repulsion may be accomplished in a feasible way. Regarding its
thermodynamics, the specific heat peak shifts to lower temperature as $h$
increases.

2
The categories of this paper are: math
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph