Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of 4- and 6-magnon bound-states in the spin-anisotropic
  frustrated antiferromagnet FeI$_2$   Spin-waves e.g. magnons are the conventional elementary excitations of
ordered magnets. However, other possibilities exist. For instance, magnon
bound-states can arise due to attractive magnon-magnon interactions and
drastically impact the static and dynamic properties of materials. Here, we
demonstrate a zoo of distinct multi-magnon quasiparticles in the frustrated
spin-1 triangular antiferromagnet FeI$_2$ using time-domain terahertz
spectroscopy. The energy-magnetic field excitation spectrum contains signatures
of one-, two-, four- and six-magnon bound-states, which we analyze using an
exact diagonalization approach for a dilute gas of interacting magnons. The
two-magnon single-ion bound states occur due to strong anisotropy and the
preponderance of even higher order excitations arises from the tendency of the
single-ion bound states to themselves form bound states due to their very flat
dispersion. This menagerie of tunable interacting quasiparticles provides a
unique platform in a condensed matter setting that is reminiscent of the
few-body quantum phenomena central to cold-atom, nuclear, and particle physics
experiments.

21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
16
The categories of this paper are: stat