Persistent correlation between superconductivity and antiferromagnetic fluctuations near a nematic quantum critical point in FeSe1-xSx

We present Se-77-NMR measurements on FeSe1-xSx 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-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 FeSe1-xSx system.