Extended Data Fig. 3: Spin-lattice (T1) relaxation measurements for 4.

ESE saturation recovery measurements at 310 (a), 410 (b) and 720 mT (c); the frequency was 9.16 GHz and the temperature 5 K. T1 times deduced from exponential fits are displayed in each panel; the uncertainties correspond to the standard errors. See Supplementary Information Section 4 for further details.