Microwave-power Dependence of Inverse Spin-Hall Effect Induced by Spin Pumping in Ni81Fe19/Au Thin Films

The microwave power dependence of the inverse spin-Hall effect (ISHE) induced by the spin pumping has been investigated for Ni81Fe19/Au films with changing the thickness of the Au layer. The spin pumping driven by magnetization precession injects spin currents into the Au layer, which gives rise to an electric potential difference between the edges of the Au layer via ISHE. The ISHE signal increases linearly with the microwave power for the Ni81Fe19 (20 nm)/Au (5 nm) film, which is consistent with the prediction of the conventional direct-current spin pumping model. By increasing the thickness of the Au layer, the variation of the ISHE signal changes critically. This unconventional variation indicates the coexistence of the linear and the nonlinear components in the spin-pumping induced ISHE.