Enhanced Spin–Orbit Torque Performances in PtRu–Co–PtRu–Ni–Ru-Based Spintronic Devices

Abstract

The Pt 80 Ru 20 alloy has been testified to be a satisfying heavy metal layer (HM) in spin−orbit torque (SOT)-induced spintronic devices with a relatively highspin Hall angle (θ DL ) and a low critical current density. In this work, the Pt 80 Ru 20 −Co− Ni (x Ni nm)−Ru multilayers are first prepared to find the field-free SOT-induced switching by the direct coupling of out-of-plane and in-plane ferromagnetic (FM) layers. A low in-plane assist field of −20 Oe and some optimized SOT performances are observed in the devices with x Ni = 0.4 and 0.8 nm, respectively. To further enhance the performances of the devices, a 0.6 nm thin Pt 80 Ru 20 layer is inserted between two FM layers. In the Pt 80 Ru 20 −Co−Pt 80 Ru 20 −Ni (t Ni nm)−Ru multilayers, the energy consumption decreases dramatically and a higher θ DL of 0.156 is obtained in the device with t Ni = 0.8 nm. More importantly, the field-free current-induced magnetization switching is realized in the device with t Ni = 1.4 nm. Furthermore, the interfacial Dzyaloshinskii−Moyria Interaction (DMI) can be weakened by the thin insertion as well. Our results reveal that the PtRu-based spintronic devices with enhanced SOT performances and field-free SOTdriven switching can be a promising candidate in the application of SOT-induced spintronic devices.