  The pure Kitaev honeycomb model harbors a quantum spin liquid in zero
magnetic fields, while applying finite magnetic fields induces a topological
spin liquid with non-Abelian anyonic excitations. This latter phase has been
much sought after in Kitaev candidate materials, such as $\alpha$-RuCl$_3$.
Currently, two competing scenarios exist for the intermediate field phase of
this compound ($B=7-10$ T), based on experimental as well as theoretical
results: (i) conventional multiparticle magnetic excitations of integer quantum
number vs. (ii) Majorana fermionic excitations of possibly non-Abelian nature
with a fractional quantum number. To discriminate between these scenarios a
detailed investigation of excitations over a wide field-temperature phase
diagram is essential. Here we present Raman spectroscopic data revealing
low-energy quasiparticles emerging out of a continuum of fractionalized
excitations at intermediate fields, which are contrasted by conventional
spin-wave excitations. The temperature evolution of these quasiparticles
suggests the formation of bound states out of fractionalized excitations.
