Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structure and Magnetization of Two-Dimensional Vortex Arrays in the
  Presence of Periodic Pinning   Ground-state properties of a two-dimensional system of superconducting
vortices in the presence of a periodic array of strong pinning centers are
studied analytically and numerically. The ground states of the vortex system at
different filling ratios are found using a simple geometric argument under the
assumption that the penetration depth is much smaller than the spacing of the
pin lattice. The results of this calculation are confirmed by numerical studies
in which simulated annealing is used to locate the ground states of the vortex
system. The zero-temperature equilibrium magnetization as a function of the
applied field is obtained by numerically calculating the energy of the ground
state for a large number of closely spaced filling ratios. The results show
interesting commensurability effects such as plateaus in the B-H diagram at
simple fractional filling ratios.

26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga