Inverse spin-Hall effect induced by spin pumping in metallic system

摘要

The inverse spin-Hall effect (ISHE) induced by the spin pumping has been investigated systematically in simple ferromagnetic/paramagnetic bilayer systems. The spin pumping driven by ferromagnetic resonance injects a spin current into the paramagnetic layer, which gives rise to an electromotive force transverse to the spin current using the ISHE in the paramagnetic layer. In a Ni_(81)Fe_(19)/Pt film, we found an electromotive force perpendicular to the applied magnetic field at the ferromagnetic resonance condition. The spectral shape of the electromotive force is well reproduced using a simple Lorentz function, indicating that the electromotive force is due to the ISHE induced by the spin pumping; extrinsic magnetogalvanic effects are eliminated in this measurement. The electromotive force varies systematically by changing the microwave power, magnetic-field angle, and film size, being consistent with the prediction based on the Landau-Lifshitz-Gilbert equation combined with the models of the ISHE and spin pumping. The electromotive force was observed also in a Pt/Y_3Fe_4GaO_12 film, in which the metallic Ni_(81)Fe_(19) layer is replaced by an insulating Y_3Fe_4GaO_(12) layer, supporting that the spin-pumping-induced ISHE is responsible for the observed electromotive force.