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, θ_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 × 10¹⁷ 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 (𝜌Pt to 𝜌Pt−Oxide) from 55.4 to 159.5 μΩ cm, respectively. The transverse spin Hall resistivity, 𝜌SH, is found to be proportional to the square of the longitudinal resistivity, i.e., 𝜌^impSH∝𝜌²imp, 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.