  Spin accumulation induced by spin-orbit coupling is experimentally quantified
in stack with in-plane magnetic anisotropy via the contribution of spin
accumulation to Hall resistances. Using a biasing direct current the spin
accumulation within the structure can be tuned, enabling quantification.
Quantification shows the spin accumulation can be more than ten percentage of
local magnetization, when the electric current is 1E11 A/m*m. The spin
accumulation is dependent of the thickness of Ta layer, the trend agrees with
that of spin Hall angle indicating the capability of Ta and Pt in generating
spins.
