Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Limit cycle induced frequency locking in self-sustained current
  oscillations of superlattices   The ac response of self-sustained current oscillations (SSCOs) in GaAs/AlAs
superlattices (SLs) is derived based on the deformation of a limit cycle under
an external ac driving force. Frequency locking into an integer fraction of the
ac frequency is obtained in a periodic response in which a limit cycle deforms
either with or without a topological change. This frequency locking is robust
against the ac bias because a limit cycle can adjust itself. The results are
verified both numerically and experimentally, indicating that SSCOs in SLs can
be understood within the framework of the general concepts and principles of
nonlinear physics.

11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc