Patterned media with composite in-plane and perpendicular anisotropy recording layers

Magnetization reversal mechanism in nanostructures composed of exchange coupled bi-layers with in-plane and perpendicular anisotropy was investigated. Micromagnetic simulation was carried out for bit-patterned media with areal density of 5 Tb/in², as example. Magnetization of thermally stable recorded bit using a single layer may not switch under write field. However, a complete and fast switching is possible with an exchange coupling to a layer with in-plane anisotropy. By adjusting the thicknesses and intrinsic properties of the two layers, the composite recording layer still can retain perpendicular anisotropy. The exchange coupled structure with dual-anisotropy can be extended to magnetic memories.