  We theoretically investigate a manipulation method of nonequilibrium spin
accumulation in the paramagnetic normal metal of a spin pumping system, by
using the spin precession motion combined with the spin diffusion transport. We
demonstrate based on the Bloch-Torrey equation that the direction of the
nonequilibrium spin accumulation is changed by applying an additional external
magnetic field, and consequently, the inverse spin Hall voltage in an adjacent
paramagnetic heavy metal changes its sign. We find that the spin relaxation
time and the spin diffusion length are simultaneously determined by changing
the magnitude of the external magnetic field and the thickness of the normal
metal in a commonly-used spin pumping system.
