Enhanced Spin–Orbit Torque and Low Critical Current Density in Pt_100–xRu_x/[CoNi]/Ru Multilayer for Spintronic Devices

Using a heavy-metal (HM) alloy layer in spin–orbit torque (SOT)-based devices is an effective method for obtaining a high current–spin conversion efficiency θSH. In this work, SOT-based spintronic devices with a Pt100–xRux-alloyed HM layer are studied by applying harmonic Hall measurements and magneto-optical Kerr effect microscopy to detect the θSH and to observe the process of current-induced magnetization switching. Both the highest θSH of 0.132 and the lowest critical current density (Jc) of 8 × 105 A/cm2 are realized in a device with x = 20, which satisfies the high SOT efficiency and low energy consumption simultaneously. The interfacial Dzyaloshinskii–Moriya interaction can be overcome by increasing the in-plane assist field. Meanwhile, the minimum in-plane field required for current-induced complete switching can be reduced to ±60 Oe. Our study reveals that using the Pt–Ru alloyed HM layer is an effective route for SOT application with enhanced performance.