Role of Nematic Fluctuations on Superconductivity in FeSe${}_{0.47}$Te${}_{0.53}$ Revealed by NMR under Pressure

Abstract

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 ${}^{77}$Se and ${}^{125}$Te nuclear magnetic resonance studies of FeSe${}_{0.47}$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 FeSe${}_{0.47}$Te${}_{0.53}$. However, the contribution of AFMSF to SC in FeSe${}_{0.47}$Te${}_{0.53}$ was found to be much less compared to that in FeSe${}_{1-x}$S${}_x$, suggesting that nematic fluctuations play a dominant role in the SC in FeSe${}_{1-x}$Te${}_x$ around the nematic QCP.

8 pages, 3 figures, accepted for publication in Phys. Rev. Lett