Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Skyrmions and spin waves in frustrated ferromagnets at low applied
  magnetic field   A continuum model of frustrated ferromagnets is analyzed in detail in the
regime of low applied magnetic field, $H_0<1/4$, where the ground state is a
spatially varying conical spiral. By changing variables to a corotating spin
field, the model is reformulated as a gauged sigma model in a fixed background
gauge, allowing the construction of stable isolated Skyrmions, and stable
multi-Skyrmion clusters, which approach the conical ground state at spatial
infinity. Owing to the spatial anisotropy induced by the ground state, these
Skyrmions exhibit only discrete symmetries, and are of neither N\'eel nor Bloch
type. These Skyrmions are continuously connected to the more familar solutions
in the high field regime ($H_0>1/4$), acquiring axial symmetry in the limit
$H_0\rightarrow 1/4$. The propagation of small amplitude spin waves through the
conical ground state is also analyzed and is found to depend strongly on both
$H_0$ and propagation direction relative to the ground state. In contrast to
spin waves in the high field regime ($H_0>1/4$) there is no spectral gap: waves
may propagate with any angular frequency.

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The categories of this paper are: stat
12
The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int