Enhanced Gilbert Damping in Thin Ferromagnetic Films

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.

• NS
  National Science Foundation
• SF
  Schlumberger Foundation
• NF
  Norges Forskningsråd
• DA
  Defense Advanced Research Projects Agency
• DO
  Division of Materials Research