Enhanced spin-orbit torque efficiency in Pt100-xNix alloy based magnetic bilayer*

The binary alloy/ferromagnetic metal heterostructure has drawn extensive attention in the research field of spin-orbit torque (SOT) due to the potential enhancement of SOT efficiency via composition engineering. In this work, the magnetic properties and SOT efficiency in the Pt100 - xNix/Ni78Fe22 bilayers were investigated via the spin-torque ferromagnetic resonance (ST-FMR) technique. The effective magnetic anisotropy field and effective damping constant extracted by analyzing the ST-FMR spectra show a weak dependence on the Ni concentration. The effective spin-mixing conductance of 8.40 x 10(14) omega(-1) . m(-2) and the interfacial spin transparency T-in of 0.59 were obtained for the sample of Pt70Ni30/NiFe bilayer. More interestingly, the SOT efficiency that is carefully extracted from the angular dependence of ST-FMR spectra shows a nonmonotonic dependence on the Ni concentration, which reaches the maximum at x = 18. The enhancement of the SOT efficiency by alloying the Ni with Pt shows potential in lowering the critical switching current. Moreover, alloying relatively cheaper Ni with Pt may promote to reduce the cost of SOT devices.

Automated summary

The study investigates the magnetic properties and SOT efficiency in Pt100 - xNix/Ni78Fe22 bilayers, showing that alloying Ni with Pt can enhance SOT efficiency, potentially leading to lower critical switching current and reduced cost of SOT devices.