Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field evolution of magnons in $\alpha$-RuCl$_3$ by high-resolution
  polarized terahertz spectroscopy   The Kitaev quantum spin liquid (KSL) is a theoretically predicted state of
matter whose fractionalized quasiparticles are distinct from bosonic magnons,
the fundamental excitation in ordered magnets. The layered honeycomb
antiferromagnet $\alpha$-RuCl$_3$ is a KSL candidate material, as it can be
driven to a magnetically disordered phase by application of an in-plane
magnetic field, with $H_c \sim 7$ T. Here we report a detailed characterization
of the magnetic excitation spectrum of this material by high-resolution
time-domain terahertz (THz) spectroscopy. We observe two sharp magnon
resonances whose frequencies and amplitudes exhibit a discontinuity as a
function of applied magnetic field, as well as two broader peaks at higher
energy. Below the N\'eel temperature, we find that linear spin wave theory can
account for all of these essential features of the spectra when a
$C_3$-breaking distortion of the honeycomb lattice and the presence of
structural domains are taken into account.

14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con