Magnetization reversal in Ni80Fe20/Co80Pt20 bilayers

Co80Pt20 films of varying thicknesses have been prepared by electrodeposition on Cu seed layers. The films display perpendicular magnetic anisotropy and large coercivities. Soft/hard bilayers were subsequently obtained by sputter deposition of Ni80Fe20 layers. A thorough experimental analysis of the magnetization reversal is carried out in samples with different layer thicknesses by measuring the total susceptibility, the recoil initial susceptibility and the ac reversible susceptibility as a function of the applied field, allowing to discriminate between reversible and irreversible processes and to point out exchange-spring behaviour.