Effect of Ta thickness and annealing temperature on the perpendicular magnetic anisotropy in MTJ stack with CoFeB/Ta/[Co/Pd]n as top electrode

High tunneling magnetoresistance (TMR) have recently been realized in CoFeB/MgO/CoFeB perpendicular magnetic tunnel junctions (p-MTJs). However, the perpendicular magnetic anisotropy (PMA) is still low. Ferromagnetic multilayers is known to show a high PMA, which can be combined into composite electrode such as CoFeB/Ta/[Co(Fe)/Pd(Pt)]_n to increase the thermal stability. In this kind of composite electrode, the Ta spacer layer play a critical role In this study, we investigate the effect of Ta thickness and annealing effect on the PMA in p-MTJ stack using CoFeB/Ta/[Co/Pd]_n as the top electrodes.