Ultralow-current magnetization switching in nearly compensated synthetic antiferromagnetic frames using sandwiched spin sources

Spin–orbit torque (SOT)-induced magnetization switching via electric currents in large spin–orbit-coupled heavy metal (HM)/ferromagnetic (FM) frames is one of the most reliable approaches to achieve increased performances in various spintronic applications. However, its widespread utilization is still challenging owing to the inherent requirement of a high electric current density for efficient magnetization switching. In this paper, we introduce a sandwiched synthetic antiferromagnetic (S-SyAF) frame, comprising CoFeB (FM)/W (HM)/CoFeB (FM) stacks, whose operation is mediated by the Ruderman–Kittel–Kasuya–Yosida interaction. The middle HM layer serves as a spin current source for the top and bottom FM layers simultaneously. In addition, the S-SyAF frame contributes to a substantial reduction in the net magnetization, which ensures a considerably increased SOT switching efficiency; further, the switching current was almost 10 times smaller than that in a conventional HM/FM frame. Thus, we believe that these experimental findings will provide a new avenue for designing future spintronic devices.