  An important goal of spintronics is to covert a charge current into a spin
current with a controlled spin polarization that can exert torques on an
adjacent magnetic layer. Here we demonstrate such torques in a two ferromagnet
system. A CoNi multilayer is used as a spin current source in a sample with
structure CoNi/Au/CoFeB. Spin torque ferromagnetic resonance is used to measure
the torque on the CoFeB layer. The response as a function of the applied field
angle and current is consistent with the symmetry expected for a torques
produced by the planar Hall effect originating in CoNi. We find the strength of
this effect to be comparable to that of the spin Hall effect in platinum,
indicating that the planar Hall effect holds potential as a spin current source
with a controllable polarization direction.
