Wide-range control of ferromagnetic resonance by spin Hall effect

We demonstrate experimentally that the characteristics of the ferromagnetic resonance in a microscopic magnetic system based on a Permalloy/Cu/Pt multilayer can be varied over a wide range by the spin Hall effect. Specifically, by applying a dc current through the Pt strip, we achieve a reduction of the effective damping constant in Permalloy by a factor of two below its standard value. We show that this reduction is not significantly affected by the Joule heating effects. We also find that, apart from influencing the damping, the spin Hall effect results in the amplification or suppression of the coherent magnetization dynamics. (C) 2011 American Institute of Physics. [doi:10.1063/1.3655908]