Spin-orbit torques and magnetization switching in Gd/Fe multilayers generated by current injection in NiCu alloys

Light transition metals have recently emerged as a sustainable material class for efficient spin-charge interconversion. We report measurements of current-induced spin-orbit torques generated by Ni1-xCux alloys in perpendicularly magnetized ferrimagnetic Gd/Fe multilayers. We show that the spin-orbit torque efficiency of Ni1-xCux increases with the Ni/Cu atomic ratio, reaching values comparable to those of Pt for Ni55Cu45. Furthermore, we demonstrate magnetization switching of a 20-nm-thick Gd/Fe multilayer with a threshold current that decreases with increasing Ni concentration, similar to the spin-orbit torque efficiency. Our findings show that Ni1-x Cu- x -based magnetic heterostructures allow for efficient control of the magnetization by electric currents.