Figure 5: Signatures of criticality.

(a) Temperature dependence of the relaxation frequency ν_p and (b) of the relaxation strength Δε at three different internal magnetic fields. (c) (H_i,T) diagram and contour plot of the peak frequency ν_p=1/(2πτ) of the dielectric loss (same colour legend as in Fig. 4). The position of FWHM of ν_p(H_i) (blue dots) approximately obey T~T_c~|H_i−H_i,c|^2/3 scaling (blue line). (d) Quasistatic permittivity ε_10Hz measured at ν=10 Hz. The inflection points of its field dependence are marked in (c) as yellow dots. The origin of error bars is discussed in detail in Supplementary Fig. 4.