In-plane current-induced strong dampinglike spin-orbit torque (SOT) can enable sub-nanosecond switching of thin-film nanomagnets for nonvolatile magnetic storage [1]. Enormous efforts have been made on developing energy-efficient, high-endurance, integration-friendly spin current generators (SCGs) [2], [3] that can provide high dampinglike SOT efficiency (xi DL j). This is mainly motivated by the fact that xi DL j of a SCG/ferromagnet (FM) heterostructure directly connects to the density of the critical switching current inside the SCG layer (j c) and thus the total switching current (I c, the sum of the currents in the SCG and the FM layers) that will define the energy efficiency (I c 2), the scalability (the transistor dimension ∝ I c), and the endurance (electro-immigration I c2) of spin-orbit torque magnetic tunnel junctions (SOT-MTJs). © 2021 IEEE.