The relationship between antiferromagnetic (AFM) spin fluctuations (SF), nematic fluctuations, and superconductivity (SC) has been central to understanding the pairing mechanism in iron-based superconductors (IBSCs). Iron chalcogenides, which hold the simplest crystal structure in IBSCs, provide a good platform to investigate the relationship. Here, we report ${}^{77}\mathrm{Se}$ and ${}^{125}\mathrm{Te}$ nuclear magnetic resonance studies of ${\mathrm{FeSe}}_{0.47}{\mathrm{Te}}_{0.53}$, which is located close to a nematic quantum critical point (QCP), under pressures up to 1.35 GPa. Both the superconducting critical temperature and AFMSF were found to be enhanced under pressure, which suggests a correlation between SC and AFMSF in ${\mathrm{FeSe}}_{0.47}{\mathrm{Te}}_{0.53}$. However, the contribution of AFMSF to SC in ${\mathrm{FeSe}}_{0.47}{\mathrm{Te}}_{0.53}$ was found to be much less compared to that in ${\mathrm{FeSe}}_{1-x}{\mathrm{S}}_x$, suggesting that nematic fluctuations play a dominant role in the SC in ${\mathrm{FeSe}}_{1-x}{\mathrm{Te}}_x$ around the nematic QCP.

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• Nematic order
• Superconductivity
• Iron-based superconductors
• Strongly correlated systems
• Nuclear magnetic resonance
• Nuclear magnetic resonance relaxation rate