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Exchange magnetic field torques in YIG/Pt bilayers observed by the spin-Hall magnetoresistance

The effective field torque of an yttrium-iron-garnet film on the spin accumulation in an attached Pt film is measured by the spin-Hall magnetoresistance (SMR). As a result, the magnetization direction of a ferromagnetic insulating layer can be measured electrically. Experimental transverse and longitudinal resistances are well described by the theoretical model of SMR in terms of the direct and inverse spin-Hall effect, for different Pt thicknesses [3, 4, 8 and 35nm]. Adopting a spin-Hall angle of Pt $θ_{SH}=0.08$, we obtain the spin diffusion length of Pt ($λ=1.1\pm0.3$nm) as well as the real ($G_r=(7\pm3)\times10^{14}Ω^{-1}$m$^{-2}$) and imaginary part ($G_i=(5\pm3)\times10^{13}Ω^{-1}$m$^{-2}$) of the spin-mixing conductance and their ratio ($G_r/G_i=16\pm4$).