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

Ando, Kazuya*; Takahashi, Saburo; Ieda, Junichi   ; Kajiwara, Yosuke*; Nakayama, Hiroyasu*; Yoshino, Tatsuro*; Harii, Kazuya*; Fujikawa, Yasunori*; Matsuo, Mamoru*; Maekawa, Sadamichi; Saito, Eiji

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 NiFe/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 entirely to the ISHE induced by the spin pumping; the extrinsic magnetogalvanic effects are eliminated in this measurement. The electromotive force varies systematically by changing the microwave power, magnetic-field angle, and film size, which are well reproduced by a calculation 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/YFeGaO film, in which the metallic NiFe layer is replaced by an insulating YFeGaO layer, supporting that the spin-pumping-induced ISHE is responsible for the observed electromotive force.