Impact of nematicity on the relationship between antiferromagnetic fluctuations and superconductivity in FeSe0.91S0.09 under pressure*

Relationships between nematicity, antiferromagnetism and superconductivity have been a central theme for studies of iron based superconductors. When these systems undergo a nematic transition, the four-fold rotational symmetry (C4) of antiferromagnetic correlations reduces to two-fold (C2). The positive relationship between antiferromagnetic correlations and superconducting transition temperatures Tc is clearly seen in unconventional superconductors, but does this relationship depend on the symmetry of the correlations? We will present the findings of our high pressure NMR and resistivity study on FeSe0.91S0.09 system [1] demonstrating that this relationship changes with the presence/absence of nematicity and also that C4 symmetric antiferromagnetic correlations are better in enhancing Tc than C2 symmetric counterparts. This discovery gives a novel insight into the relationships between nematicity, antiferromagnetism and superconductivity.

[1] K. Rana, et al., “Impact of nematicity on the relationship between antiferromagnetic fluctuations and superconductivity in FeSe0.91S0.09 under pressure”, Phys. Rev. B. 101, 180503(R) (2020).