FIG. 7.
(Color online) Magic echo amplitudes for lattices of classical spins as a function of ω1 during the π/2 pulses of the magic sandwich. As in Fig. 6 the RF amplitude during the spin-locking pulses (periods C and D in Fig. 1) was kept constant. The values of τ are 0.2 (▪/black), 0.5 (⋆/red), 1 (▴/blue), 2 (▾/green), 4 (◂/orange), and 8 (▸/purple) corresponding to τDeff = 0.14, 0.36, 0.71, 1.4, 2.8, and 5.7, respectively. The effective dipolar coupling strength is Deff = 0.71, as determined by the linewidth. Note that the values of τDeff are smaller here than nearly all the values in Fig. 6 and that, correspondingly, the variation in echo amplitude is smaller.