Reorientable Spin Direction for Spin Current Produced by the Anomalous Hall Effect
Abstract
We show experimentally that the spin direction of the spin current generated by spin-orbit interactions within a ferromagnetic layer can be reoriented by turning the magnetization direction of this layer. We do this by measuring the fieldlike component of spin-orbit torque generated by an exchange-biased Fe95Gd5 thin film and acting on a nearby Co40Fe40B20 layer. The relative angle of the Co40Fe40B20 and Fe95Gd5 magnetic moments is varied by applying an external magnetic field. We find that the resulting torque is in good agreement with predictions that the spin current generated by the anomalous Hall effect from the Fe95Gd5 layer depends on the Fe95Gd5 magnetization direction mFeGd according to σ→(y·mFeGd)mFeGd, where y is the in-plane direction perpendicular to the applied charge current. Because of this angular dependence, the spin-orbit torque arising from the anomalous Hall effect can be nonzero in a sample geometry for which the spin Hall torque generated by nonmagnetic materials is identically zero. © 2018 American Physical Society.