Enhancement of Damping-Like Spin-Orbit-Torque Efficiency in Synthetic Antiferromagnetic System using Pt-Cu Alloy

Damping-like spin-orbit torque (SOT) efficiency (effective spin Hall angle: ξ DL ) is investigated in synthetic antiferromagnetic (AF) systems using Pt-Cu alloy/Ir/Pt-Cu alloy spacer layers. AF interlayer exchange coupling through Pt-Cu alloy/Ir/Pt-Cu alloy spacer layers was observed. We also found that the magnitude of ξ DL for synthetic AF system using Pt 57 Cu 43 alloy/Ir/ Pt 57 Cu 43 alloy spacer layer is larger than that for synthetic AF system using Pt/Ir/Pt spacer layer, comparing to devices with nearly similar magnitudes of interlayer exchange coupling of 0.11 mJ/m ² . The observed maximum magnitude of ξ DL is 19.9% for the synthetic AF system using Pt 57 Cu 43 alloy/Ir/Pt 57 Cu 43 alloy. The synthetic AF system will be a promising building block for future nonvolatile high-speed memories and logic circuits using the spin Hall effect.