Large modulation of spin-orbit torques in IrMn/CoFeB/MgO heterostructures with optimized perpendicular magnetic anisotropy

Abstract Spin-orbit torques (SOTs) and perpendicular magnetic anisotropy (PMA) are of great technical relevance for new generation spintronics applications. Here, we present a prominent tuning effect of annealing on SOT and PMA in IrMn/CoFeB/MgO/SiO2 heterostructures. By systematically changing the thicknesses of Co40Fe40B20 and IrMn, and annealing temperature, the phase diagrams of PMA are obtained. The SOTs are quantified by harmonic Hall voltage measurements. Both the damping-like and field-like SOT efficiencies show a nonmonotonic variation with annealing temperature, which can be further correlated with the device resistivity. Our work contributes a reference for fabricating perpendicularly magnetized CoFeB on seed layer-free IrMn and for tuning SOTs by annealing.