Hysteresis loops of multilayer films Ta (50 nm)/[Nd–Fe–B (30nm)/Nd (3 nm)/Ta (1 nm)/Fe₂Co (10 nm)/Ta (1 nm)]_N/Nd–Fe–B (30 nm)/Nd (3 nm)/Ta (20 nm): (a) N = 4, (b) N = 9, (c) N = 14, and (d) N = 19.^[22]