Fig. 3
From: Tuning the interplay between nematicity and spin fluctuations in Na1−xLi x FeAs superconductors
75As NMR spectra in Na1−xLi x FeAs for H || c. a–e Temperature dependence of the central line as a function of Li doping x measured at 9.1 T. For x = 0 and 0.02, the 75As line rapidly disappears below TSDW due to the large hyperfine field resulting from the static Fe spin moment arranged antiferromagentically. For x ≥ 0.03, the 75As intensity remains finite down to low temperatures without a significant broadening, indicating the absence of long range magnetic order. f The AFM split 75As lines were detected at low temperatures for x = 0 and 0.02, manifesting the commensurate AFM phase. g The Knight shift \({\cal K}\) as a function of temperature and doping at 9.1 T parallel to c. The almost constant \({\cal K}\) for a given x is rapidly reduced for x ≥ 0.03, suggesting a change of the Fermi surface geometry
