Impact of Nematicity on the Relationship between Antiferromagnetic Fluctuations and Superconductivity in FeSe0.91S0.09 Under Pressure

Abstract

The sulfur substituted FeSe system, FeSe${}_{1-x}$S${}_x$, provides a versatile platform for studying the relationship between nematicity, antiferromagnetism, and superconductivity. Here, by nuclear magnetic resonance (NMR) and resistivity measurements up to 4.73 GPa on FeSe${}_{0.91}$S${}_{0.09}$, we established the pressure($p$)-temperature($T$) phase diagram in which the nematic state is suppressed with pressure showing a nematic quantum phase transition (QPT) around $p$ = 0.5 GPa, two SC regions, separated by the QPT, appear and antiferromagnetic (AFM) phase emerges above $\sim$3.3 GPa. From the NMR results up to 2.1 GPa, AFM fluctuations are revealed to be characterized by the stripe-type wavevector which remains the same for the two SC regions. Furthermore, the electronic state is found to change in character from non-Fermi liquid to Fermi liquid around the nematic QPT and persists up to $\sim$ 2.1 GPa. In addition, although the AFM fluctuations correlate with $T_{\mathrm{c}}$ in both SC states, demonstrating the importance of the AFM fluctuations for the appearance of SC in the system, we found that, when nematic order is absent, $T_{\mathrm{c}}$ is strongly correlated with the AFM fluctuations, whereas $T_{\mathrm{c}}$ weakly depends on the AFM fluctuations when nematic order is present. Our findings on FeSe${}_{0.91}$S${}_{0.09}$ were shown to be applied to the whole FeSe${}_{1-x}$S${}_x$ system and also provide a new insight into the relationship between AFM fluctuations and SC in Fe-based superconductors.

10 pages, 10 figures including 4 pages and 6 figures of Supplementary Material, accepted for publication in Phys. Rev. B rapid communication

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Cited by in corpus (4)

• Spin fluctuations from Bogoliubov Fermi surfaces in the superconducting state of S-substituted FeSe
• Interrelationships between nematicity, antiferromagnetic spin fluctuations and superconductivity: Role of hotspots in FeSe${}_{1-x}$S${}_x$ revealed by high pressure ${}^{77}$Se NMR study
• Unveiling the quasiparticle behaviour in the pressure-induced high-$T_c$ phase of an iron-chalcogenide superconductor
• Fragile pressure-induced magnetism in FeSe superconductors with a thickness reduction