Exchange-coupled composite media were realized by combining perpendicular hard magnetic FePtCu alloy films with perpendicular Co/Pt multilayers which are magnetically softer. We demonstrate that the switching field of the hard layer can be efficiently altered by modifying the material properties of the soft layer by varying the number of Co/Pt bilayers. Moreover, the possibility of effectively tuning the interlayer exchange coupling using rapid thermal annealing was shown. These studies were supported by theoretical modeling revealing the relevant factors to reduce the switching field of the hard layer which are important for future media design.

Magnetization reversal processes in Co/Pt multilayers prepared on nanoperforated templates are probed by magnetization relaxation measurements. The signature of pinning controlled domain wall movement as expected for percolated media is identified. This contrasts with the nucleation-type reversal mechanism of a Co/Pt reference film prepared on a smooth substrate. A zero field energy barrier of 93kBT is determined by fluctuation field measurements and is elucidated by micromagnetic calculations using the nudged elastic band method. This value is sufficiently large to qualify the material as a promising percolated medium.