Spin pumping at Permalloy/graphene interface

Abstract

Ferromagnetic resonance (FMR) measurements on Permalloy/graphene (Py/Gr) films show an enhancement of the Gilbert damping in the ferromagnetic layer as a consequence of spin pumping at the Py/Gr interface, which is driven by the Py magnetization dynamics. The remarkable increase in the FMR line-width compares with observations in other bilayer systems in which thick layers (thicker than the spin diffusion length) of heavy metals with strong spin-orbit interaction are employed as the non-magnetic layer. By reversing the stacking order of the graphene/ferromagnet, we rule out any interface effects and calculate the damping of the ferromagnet due to the graphene. Our results indicate that spin relaxation in CVD graphene must be greatly enhanced in order to account for the losses of angular momentum in the ferromagnet. © 2013 Copyright SPIE.