Effect of Inserting a Transition Metal Cu Layer on the Spin-Orbit Torque-Induced Magnetization Switching in Pt/Co/Ta Structures

Current induced spin-orbit torque (SOT) in perpendicularly magnetized heavy metal/ferromagnetic metal/heavy metal trilayers has been widely studied to achieve the current-induced magnetization switching. Decreasing the critical switching current-density (J(C)) is a primary factor in the performance of memory or logic devices because J(C) directly affects the power consumption of the devices. This work demonstrates the influences of inserting a transition metal copper (Cu) layer between the Co/Ta interface in the Pt/Co/Ta structures with perpendicular magnetic anisotropy (PMA) on the J(C), SOT, coercive field, and perpendicular magnetic anisotropy field (H-an). The results show that J(C) decreases significantly when the thickness of Cu layer is above 3 nm, compared with the Pt/Co/Ta control sample, under consideration of the shunting effect of Cu layer. The decrease of J(C) is the result of the competition between the modified SOT and H-an due to the insertion of Cu. The study suggests that the critical switching current-density of SOT-switching can be decreased by inserting a transition metal Cu layer.