Nonlocal orbital torques in magnetic multilayers

Abstract We investigate current-induced torques in Ni/Ti/Fe/Ti multilayers. In the multilayers, we find that the damping-like torque acting on the Ni magnetization increases with the thickness of the bottom Ti layer, despite the negligible spin Hall conductivity of Ti and the presence of the Fe interlayer that effectively absorbs the transverse spins. The nonlocal nature of the observed torque is consistent with the orbital torque arising from the orbital Hall effect in the Ti layer and orbital transport through the Fe layer. This observation highlights the unique features of the orbital currents, offering enhanced flexibility in the design of spintronic devices.