Reversal behavior in a bimodal magneto-optical medium

Bimodal magnetic behavior, in which Kerr rotation (θK) and ellipticity (εK) each exhibit major magneto-optic hysteresis loops with two distinct field-dependent steps, was encountered in a (0.3 nm Co/1.2 nm Pt)15 multilayer film with perpendicular magnetization. A model is postulated in which there are two different interacting magnetic entities present in the layered structure of this material, each with a stable perpendicular magnetization state either parallel or antiparallel to the applied field, and which reverse quasi-independently from one another. Due to interactions between the two, the reversals occur at the intrinsic coercivities displaced by an interaction field, Hi, whose sign depends upon the magnetization of the other phase. Using major loop and first-order reversal measurements, the intrinsic coercivities, as well as Hi, were obtained.