Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-equilibrium self-assembly of spin-wave solitons in FePt
  nanoparticles   Magnetic nanoparticles such as FePt in the L10-phase are the bedrock of our
current data storage technology. As the grains become smaller to keep up with
technological demands, the superparamagnetic limit calls for materials with
higher magneto-crystalline anisotropy. This in turn reduces the magnetic
exchange length to just a few nanometers enabling magnetic structures to be
induced within the nanoparticles. Here we describe the existence of spin-wave
solitons, dynamic localized bound states of spin-wave excitations, in FePt
nanoparticles. We show with time-resolved X-ray diffraction and micromagnetic
modeling that spin-wave solitons of sub-10 nm sizes form out of the
demagnetized state following femtosecond laser excitation. The measured soliton
spin-precession frequency of 0.1 THz positions this system as a platform to
develop miniature devices capable of filling the THz gap.

8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex