  The power flow process mediated by spin current in the bilayer device
consisting of ferromagnetic metal (FM) and non-magnetic metal (NM) layers is
examined by realizing experimental evaluations for each process from the
microwave absorption to electromotive force (EMF) output. The absorption power
by ferromagnetic resonance (FMR) of the thin FM layer during the EMF output is
directly measured in operando using an antenna probe system. The transfer
efficiency of the absorption power into the NM layer by spin pumping is
estimated from strict linewidth evaluation of EMF spectra. The maximum transfer
efficiency of the spin pumping power to the external load via the inverse spin
Hall effect is determined to be 4.2X10^(-8) under 160mW microwave irradiation
using an analysis model assuming a parallel circuit. The main factors reducing
the efficiency are found to be low resistivity of the NM layer and the
interface loss. These quantifications are important as a first step to consider
the efficient transfer of spin energy mediated by spin currents.
