Spin Pumping Induced Electric Voltage

Spin pumping in a ferromagnetic (FM) and nonmagnetic (NM) metallic bilayer generates an electric voltage whose origins have been attributed to the inverse spin Hall effect (ISHE) in the NM layer. We show that the electric voltage or current from the spin pumping is not limited to the ISHE of the NM layer; instead, there are two other previously unidentified contributions: one from the interface and the other from the FM layer. By using our newly developed spin pumping formalism, we compute the relative contributions of these three sources of the induced electric voltages. When we apply our results to a NiFe/Pt bilayer, we find the contribution from the strong spin-orbit coupled interface, known as the inverse Edelstein effect (IEE), can be as large as or even larger than that from the NM layer. Our finding indicates that the experimental estimation of the spin Hall angle and spin diffusion length of Pt should include both IEE and ISHE.