Electrical detection of direct and alternating spin current injected from a ferromagnetic insulator into a ferromagnetic metal

We report dual spin pumping in magnetic bilayers made of a ferromagnetic insulator yttrium iron garnet (YIG) and a ferromagnetic metal permalloy (Py). At the YIG ferromagnetic resonance (FMR), we detect a charge voltage in Py caused by YIG spin pumping. At the Py FMR, we measure the charge voltage generated by Py spin rectification. A striking simultaneous enhancement of both voltages is found at the equal resonance condition of both FMRs, which we attribute to dynamic coupling of the dual spin pumping. Our results demonstrate that Py enables electrical detection of both dc and ac spin currents in the spin pumping from YIG, which reveals an alternative path for developing insulator spintronics.