Spin pumping effects for Co/Ag films

Dynamic exchange coupling between two ferromagnetic cobalt (Co) thin films separated by a nonmagnetic silver (Ag) layer was investigated by means of ferromagnetic resonance (FMR) technique. Nonmagnetic Ag layer was sufficiently thick to suppress any magnetostatic coupling between the thin films of Co. Dynamical coupling is established via angular momentum exchange due to simultaneous precession of ferromagnets and as a result FMR linewidth narrows. We also confirmed the spin pumping theory's prediction on the thickness dependence of FMR linewidth such that the linewidth for thin film Co decreases exponentially as its thickness increases. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4748165]