Spin-orbit coupling is an important ingredient in many spin liquid candidate
materials, especially among the rare-earth magnets and Kitaev materials. We
explore the rare-earth chalcogenides NaYbS2​ where the Yb3+ ions form a
perfect triangular lattice. Unlike its isostructural counterpart YbMgGaO4​
and the kagom\'{e} lattice herbertsmithite, this material does not have any
site disorders both in magnetic and non-magnetic sites. We carried out the
thermodynamic and inelastic neutron scattering measurements. The magnetic
dynamics could be observed with a broad gapless excitation band up to 1.0 meV
at 50 mK and 0 T, no static long-range magnetic ordering is detected down to 50
mK. We discuss the possibility of Dirac spin liquid for NaYbS2​. We identify
the experimental signatures of field-induced transitions from the disordered
spin liquid to an ordered antiferromagnet with an excitation gap at finite
magnetic fields and discuss this result with our Monte Carlo calculation of the
proposed spin model. Our findings could inspire further interests in the
spin-orbit-coupled spin liquids and the magnetic ordering transition from them