Enhanced gilbert damping in thin ferromagnetic films

Phys Rev Lett. 2002 Mar 18;88(11):117601. doi: 10.1103/PhysRevLett.88.117601. Epub 2002 Feb 28.


The precession of the magnetization of a ferromagnet is shown to transfer spins into adjacent normal metal layers. This "pumping" of spins slows down the precession corresponding to an enhanced Gilbert damping constant in the Landau-Lifshitz equation. The damping is expressed in terms of the scattering matrix of the ferromagnetic layer, which is accessible to model and first-principles calculations. Our estimates for permalloy thin films explain the trends observed in recent experiments.