Study of Co/Pd multilayers as a candidate material for next generation magnetic media

We report a combinatorial synthesis study on the magnetic properties of sputter-deposited Co/Pd multilayers with high perpendicular anisotropy and high remnant squareness for magnetic media applications such as magnetic logic systems, bit patterned media, magneto-optical recording, and multilevel three-dimensional (3D) magnetic media. The perpendicular magnetic anisotropy in the multilayers originates from the interfacial anisotropy of the alloylike structure. The deposition conditions and subsequent microstructures of the multilayers are critical factors to determine the magnetic properties of the media. We investigated the dependence of the magnetic properties on the thickness of Co and Pd layers the number of Co/Pd bilayers. For instance, we found that a 0.26-nm-thick layer of Co would produce the highest coercivity value if paired with a 0.55-nm-thick Pd layer. Our results revealed that an Ar + milling could significantly increase the coercivity of the multilayer media. Further, we discovered that we could control the deposition pressure to achieve either granular or continuous media morphologies corresponding to exchange-coupled or decoupled grains, respectively. Finally, we used the combinatorial synthesis to tailor multilayers' properties to engineer a eight-level three-layer 3D media.