Figure 1

Figure 1: (a) In solid-state systems with large total spin on each site, spin fluctuations occur by super exchange, where, at the leading order, one spin-up is exchanged for a spin-down electron. The size of the fluctuations of Sz can only be ±1 in a total spin of S, so the fluctuations are relatively small at large S. (b) In cold-atom Fermi systems with large hyperfine spin, the atom moves as an entire object. In this case, the fluctuations of Sz can be a much larger value of ±S.