  The nuclear-to-electron spin angular momentum conversion via hyperfine
coupling in a normal metal (NM)/ferromagnet (FM) bilayer system is
theoretically investigated by using the nonequilibrium Green's function method.
The spin current generated by the nuclear magnetic resonance (NMR) is found to
be enhanced by the pulling effect in the FM when the temperature is lower than
NMR resonance frequency. In a Co/Pt bilayer system, we show that the spin
current by NMR becomes larger than that of the ferromagnetic resonance (FMR).
