Reorientable Spin Direction for Spin Current Produced by the Anomalous Hall Effect

Ferromagnets with strong spin-orbit interactions are expected to generate spin currents via the anomalous Hall effect. These spin currents are predicted to differ from those generated by the spin Hall effect from a nonmagnetic material in that they should have a spin polarization always parallel to the magnetization of the source layer. Hence, by manipulation this magnetic state, one may control the resulting spin-orbit torques and generate torques that are forbidden by symmetry for the conventional spin Hall effect. We report quantitative measurements of spin torques in pinned ferromagnet/spacer/free ferromagnet samples, as a function of changing the relative angle between the magnetizations of the two magnetic layers. We show experimentally that the spin direction of the spin current generated by a magnetic layer can be reoriented by turning its magnetization direction, and that this allows the spin-orbit torque arising from the anomalous Hall effect to be non-zero in a geometry for which the spin Hall torque generated by non-magnetic materials is identically zero. We will report initial results on the relative strength of this anomalous Hall torque from different ferromagnetic materials.