Physical Principles of Spin Pumping

The spin pumping is a versatile method to create the spin current and spin accumulation in various conducting materials in hybrid nanostructures. In this chapter a theoretical description for spin pumping from a ferromagnet into a normal metal is presented based on the spin-exchange interaction between localized moments and conduction electrons in hybrid nanostructures. It is demonstrated that pure spin currents are generated by the coherent spin pumping due to ferromagnetic resonance and the thermal spin pumping due to the spin Seebeck effect. The inverse effect that the spin dynamics is manipulated by spin injection into a ferromagnet from a normal metal with strong spin-orbit coupling using the spin-Hall effect is also discussed.