Theory of the acoustic spin pumping

•Acoustically driven spin pumping in a ferromagnet/normal-metal bilayer is discussed.•Landau–Lifshitz–Gilbert equation combined with Bloch equation is solved by linear response.•Ferromagnet and normal-metal are modeled to interact via s–d exchange coupling.•Sounds and magnetization are modeled to interact via exchange magnetostriction.•Spin pumping signal is shown to be proportional to the input acoustic power.

Spin pumping refers to the spin current injection driven by magnetization dynamics from a ferromagnet into adjacent nonmagnetic conductors. Conventionally, ferromagnetic resonance is used to drive the magnetization dynamics and the spin pumping. Recently a new type of spin pumping driven by acoustic waves, i.e., the acoustic spin pumping, has been reported. We present a linear-response theory of the acoustic spin pumping.