Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of anomalous amplitude modes in the kagome metal
  CsV$_3$Sb$_5$   The charge-density wave (CDW) phase is often accompanied by the condensation
of a soft acoustic phonon mode, giving rise to lattice distortion and charge
density modulation. This picture was challenged for the recently discovered
kagome metal CsV$_3$Sb$_5$, based on the evidence of absence of soft phonons.
Here we report the observation of Raman-active CDW amplitude modes in this
material, which are collective excitations typically thought to emerge out of
frozen soft phonons. The amplitude modes strongly hybridize with other
superlattice modes, imparting them with clear temperature-dependent frequency
shift and broadening, rarely seen in other known CDW materials. Both the mode
mixing and the large amplitude mode frequencies suggest that the CDW exhibits
the character of strong electron-phonon coupling, a regime in which acoustic
phonon softening can cease to exist. The observation of amplitude modes in the
absence of soft phonons highlights the unconventional nature of the CDW in
CsV$_3$Sb$_5$.

11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an