Manipulation of spin–orbit torque and Dzyaloshinskii-Moriya interaction by varying Mn concentration in Pt 1- x Mn x /Co bilayer

Reducing critical current density ( JC ) of current-driven magnetization switching via power-efficient spin–orbit torque (SOT) is a key challenge in spin-based memory and logic devices. The Pt 1- x Mn x alloy shows prospect for enhancing the damping-like SOT efficiency ( ξDL ) while maintaining relatively low resistivity and power consumption. In this work, we investigated the Mn concentration  x  dependence of ξDL in Pt 1- x Mn x /Co bilayer and observed a nonmonotonic variation with the maximum ξDL  ≈ 0.25 appearing around x  = 0.2. The increase of the Pt 1- x Mn x layer resistivity is the main contribution to the enhancement of ξDL. Mn atoms doped in Pt not only modulate ξDL originating from the spin Hall effect of the Pt 1- x Mn x layer, but also affect the interfacial phenomena at the Pt 1- x Mn x /Co interface. We find that the related interfacial Dzyaloshinskii-Moriya interaction (DMI) is also tunable by  x  with the maximum appearing around x  = 0.15. The significantly reduced JC of Pt 1- x Mn x /Co bilayer is mainly due to the enhancement of ξDL and the attenuation of effective perpendicular magnetic anisotropy energy density. Meanwhile, Pt 1- x Mn x /Co bilayer maintains low power consumption and necessary thermal stability. Our work highlights the potential of alloying Pt with Mn as a valuable means to achieve high-performance SOT spintronic devices.