Persistent Correlation between Superconductivity and Antiferromagnetic Fluctuations near a Nematic Quantum Critical Point in FeSe1-xSx

We present $^{77}\mathrm{Se}$-NMR measurements on ${\mathrm{FeSe}}_{1\ensuremath{-}x}{\mathrm{S}}_{x}$ samples with sulfur content $x=0%$, 9%, 15%, and $29%$. Twinned nematic domains are observed in the NMR spectrum for all samples except $x=29%$. The NMR spin-lattice relaxation rate shows that antiferromagnetic (AFM) fluctuations are initially enhanced between $x=0%$ and $x=9%$, but are strongly suppressed for higher $x$ values. The observed behavior of the AFM fluctuations parallels the superconducting transition temperature ${T}_{\mathrm{c}}$ in these materials, providing strong evidence for the primary importance of AFM fluctuations for superconductivity, despite the presence of nematic quantum criticality in the ${\mathrm{FeSe}}_{1\ensuremath{-}x}{\mathrm{S}}_{x}$ system.