Nature Phys. 11, 570–575 (2015)

The spin Hall effect is a transport phenomenon, originating from the spin–orbit interaction, resulting in spin accumulation on the surfaces of a conductor when a current flows through it. In non-magnetic materials with large spin–orbit coupling, it can lead to significant spin accumulation at the interface between these materials and ferromagnets, whose magnetization can be switched as a result of the concomitant spin–orbit torque generated. Now, Can Onur Avci and colleagues show that the longitudinal resistance of Ta/Co and Pt/Co bilayers changes when the current flow is reversed or the sign of the magnetization is inverted, which is another consequence of the spin accumulation. The resistance is minimum if the spin at the interface and the magnetization of the cobalt layer are parallel, whereas it is maximum if they are antiparallel. This behaviour enables two-terminal spintronic devices to be produced where the current controls the magnetization and its switching is detected through resistance measurements.