Geometry dependence on inverse spin Hall effect induced by spin pumping in Ni ₈₁Fe ₁₉/Pt films

Geometric effects on the inverse spin Hall effect (ISHE) induced by the spin pumping driven by the ferromagnetic resonance (FMR) have been investigated quantitatively. We measured the FMR spectra and the electromotive force induced by the ISHE with changing the size and the thickness in Ni ₈₁Fe ₁₉/Pt films. The intensity of generated charge currents due to the ISHE changes systematically with changing the film geometry, which is consistent with the prediction of the ISHE. The experimental results show a clear difference between Ni ₈₁Fe ₁₉ and Pt thickness dependence of the ISHE induced by the spin pumping. With a constant Pt thickness, the intensity of the generated charge current is kept proportional to that of the injected spin-current density, which decreases with increased spin relaxation in the Ni ₈₁Fe ₁₉ layer due to interfacial effect, inversely proportional to its film thickness. On the other hand, reflecting the spin diffusion mechanism in the Pt layer, the charge current decreases significantly with the decrease of the Pt thickness, while injected spin-current density is almost kept constant.