  The sulfur-substituted FeSe, FeSe$_{1-x}$S$_{x} $, is one of the unique
systems that provides an independent tunability of nematicity,
antiferromagnetism and superconductivity under pressure ($p$). Recently Rana et
al. [Phys. Rev. B 101, 180503(R) (2020)] reported, from $^{77}$Se nuclear
magnetic resonance (NMR) measurements on FeSe$_{0.91}$S$_{0.09}$ under
pressure, that there exists a clear role of nematicity on the relationship
between antiferromagnetic (AFM) spin fluctuations and superconducting
transition temperature ($T_{\rm c}$) where the AFM spin fluctuations are more
effective in enhancing $T_{\rm c}$ in the absence of nematicity than with
nematicity. Motivated by the work, we carried out $^{77}$Se NMR measurements on
FeSe$_{1-x}$S$_{x}$ with $x$= 0.15 and 0.29 under pressure up to 2.10 GPa to
investigate the relationship in a wide range of $x$ in the FeSe$_{1-x}$S$_x$
system. Based on the new results together with the previously reported data for
$x$=0 [P. Wiecki et al., Phys. Rev. B 96, 180502(R) (2017)] and 0.09 [K. Rana
et al. Phys. Rev. B 101, 180503(R) (2020)], we established a $p$ - $x$ -
temperature ($T$) phase diagram exhibiting the evolution of AFM spin
fluctuations. From the systematic analysis of the NMR data, we found that the
superconducting (SC) state in nematic state arises from a non Fermi liquid
state with strong stripe-type AFM spin fluctuations while the SC state without
nematicity comes from a Fermi liquid state with mild stripe-type AFM spin
fluctuations. Furthermore, we show that the previously reported impact of
nematicity on the relationship between AFM fluctuations and superconductivity
holds throughout the wide range of $x$ from $x$ = 0 to 0.29 in
FeSe$_{1-x}$S$_{x}$ under pressure. We discuss the origin of the role of
nematicity in terms of the different numbers of hotspots on Fermi surfaces with
and without nematicity.
