Controllable Spin-Orbit Torque Efficiency in Pt/Co/Ru/Co/Pt Multilayers with Interlayer Exchange Couplings

The magnetization manipulation by the current-induced spin-orbit torque opens a prospect for energy-efficient spintronic applications. Here, we investigate controllable spin-orbit torques (SOTs) realized by interlayer exchange coupling (IEC) in Pt/Co/Ru/Co/Pt stacks. The interlayer magnetization realignments originate from the competition between itinerant electron diffusion and current-induced spin current relaxation, and it is revealed that the long-ranged interlayer antiparallel orders exist with a Ru spacer thickness of 2.3 nm. The current-induced hysteresis-loop-shift method is used to assess the H-z(eff)/J depending on the different spacer thicknesses. The loop shift distributions are revealed with the H-z(eff) phase diagrams to characterize the difference between FM-IEC and AFM-IEC. Combining with micromagnetic simulations, a possible transition mechanism of H-z(eff)/J is discussed by combining magnetization switching with the in-plane bias field in IEC systems. This work demonstrates that the spin current realigned IEC mechanism can efficiently control the SOTs in both ferromagnetic and antiferromagnetic multilayers.