Magnetic aftereffect in a bimodal Co/Pt magneto-optical medium

Magneto-optical Kerr effect measurements were used to perform magnetic afte reffect studies of the reversal behavior in a bimodal magneto-optical mediu m with perpendicular magnetic anisotropy. This (0.3 nm Co/1.2 nm Pt)(15) mu ltilayer film has shown both the Kerr rotation (theta(K)) and ellipticity ( epsilon(K)) to exhibit major hysteresis loops with two distinct field-depen dent steps. However, whereas both steps in the theta(K) loop occur in the s ame direction, in the epsilon(K) loop they occur in opposite directions. Th us, upon traversing the descending major loop, at the first magnetic revers al, epsilon(K) increases even though the magnetization decreases. Magnetic aftereffect in this material was investigated in the vicinity of each magne tization step by measuring both theta(K) and epsilon(K) over time. The data clearly show the time dependence of each of the two separate reversals, in cluding the changes in epsilon(K) which occur in opposite directions. (C) 1 999 American Institute of Physics. [S0021-8979(99)33508-8].