Highly dose dependent damping-like spin-orbit torque efficiency in O-implanted Pt

Damping-like torque (DLT) arising from the spin Hall effect (SHE) in heavy metals and their alloys has been widely explored for applications in spin-orbit torque MRAM, auto-oscillations, spin waves, and domain wall motion. In conventional materials, the DLT efficiency is limited by intrinsic properties, while attaining strong spin-orbit coupling and higher spin-charge interconversion, with no compromise to electric properties, is the need of the hour. In this Letter, we report more than 3.5 times increase in DLT efficiency, theta(DL), of modified Pt-oxide by employing a better approach of low energy 20 keV O+ ion implantation. The highest fluence of O+ implantation (1 x 10(17) ions cm(-2)) in Pt enhanced the DLT efficiency from 0.064 to 0.230 and improved the spin transmission for a smaller trade-off in the longitudinal resistivity (rho(Pt) to rho(Pt-Oxide)) from 55.4 to 159.5 mu Omega cm, respectively. The transverse spin Hall resistivity, rho(SH), is found to be proportional to the square of the longitudinal resistivity, i.e., rho(imp)(SH) proportional to rho(2)(imp), implying that the enhanced SHE in O-implanted Pt is due to a side-jumping mechanism. Further, no break in the twofold as well as mirror symmetry of torques from the O-implanted Pt allows the use of spin-torque ferromagnetic resonance-based line shape analysis to quantify such torques. Published under an exclusive license by AIP Publishing.

Automated summary

In this study, the damping-like torque efficiency was increased more than 3.5 times by using a better approach of low energy O+ ion implantation in modified Pt-oxide. The spin transmission was improved with a smaller trade-off in the longitudinal resistivity, and the enhanced spin Hall effect in O-implanted Pt was attributed to a side-jumping mechanism. The torques from the O-implanted Pt remained twofold and symmetrical, allowing for quantification using spin-torque ferromagnetic resonance-based line shape analysis.