Figure 3 : NMR spectra with doping and temperature dependence of 1/T1 at optimal doping.

From: Quantum criticality in electron-doped BaFe2−xNixAs2

Figure 3

75As-NMR spectra obtained by sweeping the frequency at a fixed external field H0=11.998 T applied along the c axis. (a) The spectra above and below TN=74 K for x=0.05. Solid, dashed and dotted lines indicate, respectively, the position of the central transition, left- and right-satellites, when an internal magnetic field develops. (b) The spectra above and below TN=48 K for x=0.07. The red curve represents the simulations by assuming a Gaussian distribution of the internal magnetic field. The black arrow indicates the position at which T1 is measured below TN. (c) The central transition line at and below Tc for x=0.10. The spectrum shift at T=1.89 K is due to a reduction of the Knight shift in the superconducting state. (d) The temperature dependence of 1/T1 for x=0.07. The solid and dashed lines show the T3- and T-variation, respectively. The solid and dashed arrows indicate Tc and TN, respectively. The error bar in 1/T1 is the s.d. in fitting the nuclear magnetization recovery curve.