Comparison of calculated hysteresis loops with experimental loops for Cr(50 nm)/[SmCo₆(9 nm)/Cu(x nm)/Fe(5 nm)/Cu(x nm)]₆/Cr(100 nm)/a-SiO₂ (x = 0–0.75). (a) The black squares are for the sample with x = 0 annealed at 500 °C measured at 10 K while the red circles are for the sample with x = 0.75 annealed at 500 °C measured at 10 K. (b) The black lines are for t^h = 9 nm, t^s = 5 nm, and A^hs = 1.8 × 10⁻⁶ erg/cm; while the red lines are for t^h = 9 nm, t^s = 5 nm, and A^hs = 0.9 × 10⁻⁶ erg/cm using OOMMF.