Interfacial exchange coupling and magnetization reversal in perpendicular [Co/Ni]_N/TbCo composite structures

Interfacial exchange coupling and magnetization reversal characteristics in the perpendicular heterostructures consisting of an amorphous ferrimagnetic (FI) Tb_xCo_100-x alloy layer exchange-coupled with a ferromagnetic (FM) [Co/Ni]_N multilayer have been investigated. As compared with pure Tb_xCo_100-x alloy, the magnetization compensation composition of the heterostructures shift to a higher Tb content, implying Co/Ni also serves to compensate the Tb moment in TbCo layer. The net magnetization switching field H_c⊥ and interlayer interfacial coupling field H_ex, are not only sensitive to the magnetization and thickness of the switched Tb_xCo_100-x or [Co/Ni]_N layer, but also to the perpendicular magnetic anisotropy strength of the pinning layer. By tuning the layer structure we achieve simultaneously both large H_c⊥ = 1.31 T and H_ex = 2.19 T. These results, in addition to the fundamental interest, are important to understanding of the interfacial coupling interaction in the FM/FI heterostructures, which could offer the guiding of potential applications in heat-assisted magnetic recording or all-optical switching recording technique.