Effect of different seed layers with varying Co and Pt thicknesses on the magnetic properties of Co/Pt multilayers

Magnetic and structural properties of Co/Pt multilayers with varying Co (t(Co)) and Pt (t(Pt)) thickness grown on various seed layers have been examined. It is challenging to grow Co/Pt multilayers as a top electrode with high perpendicular magnetic anisotropy (PMA) for magnetic tunnel junctions which usually comprise of CoFeB/MgO/CoFeB. We show that a thicker Pt layer of 1.2 nm is necessary to attain effective anisotropy (K-eff) up to 0.14 MJ/m(3). On the other hand, Co/Pt multilayers with high PMA have been achieved for proper textured seed layers of Ru and Pt. In the case of Ru seed layer, a higher K-eff = 0.45 MJ/m(3) can be achieved for t(Co) = 0.5 nm and t(Pt) = 0.2 nm. This can be attributed to the lower lattice mismatch (similar to 4%) within the multilayers and hence a more coherent CoPt (111) structure. Finally, we note that the film roughness could play an important role in influencing the PMA of the multilayers. The highest K-eff similar to 0.6 MJ/m(3) is achieved for Pt seed layer. (C) 2015 AIP Publishing LLC.