Theory of the acoustic spin pumping

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.