Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface spin waves in superconducting and insulating ferromagnets   Surface magnetization waves are studied on a semi-infinite magnetic medium in
the perpendicular geometry. Both superconducting and insulating ferromagnets
are considered. Exchange and dipole energies are taken into account, as well as
retardation effects. At large wave vectors, the spectrum for a superconductor
and insulator is the same, though for the former the branch is terminated much
earlier than for the latter due to excitation of plasmons. At small wave
vectors, the surface wave is more robust in the superconductor since it is
separated from the bulk continuum by a finite gap.

5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph