Sign Reversal of Fieldlike Spin-Orbit Torque in an Ultrathin Cr /Ni Bilayer

Spin-orbit torque (SOT) is a promising means to control magnetization dynamics in spintronic applications. Much effort has been devoted to addressing the physical origin of SOT, and improving its efficiency. The authors observe an abrupt enhancement of SOT for Cr thinner than 6 nm in a Cr/Ni heterostructure, and more remarkably a change in the sign of the fieldlike torque, due to a very strong Rashba interaction. This purely interfacial effect could provide a basis for extended functionality in next-generation memory and logic devices.