Spin pumping is a mechanism that generates spin currents from ferromagnetic resonance over macroscopic interfacial areas, thereby enabling sensitive detection of the inverse spin Hall effect that transforms spin into charge currents in nonmagnetic conductors. Here we study the spin-pumping-induced voltages due to the inverse spin Hall effect in permalloy/normal metal bilayers integrated into coplanar waveguides for different normal metals and as a function of angle of the applied magnetic field direction, as well as microwave frequency and power. We find good agreement between experimental data and a theoretical model that includes contributions from anisotropic magnetoresistance and inverse spin Hall effect. The analysis provides consistent results over a wide range of experimental conditions as long as the precise magnetization trajectory is taken into account. The spin Hall angles for Pt, Pd, Au, and Mo were determined with high precision to be 0.013Ϯ 0.002, 0.0064Ϯ 0.001, 0.0035Ϯ 0.0003, and −0.0005Ϯ 0.0001, respectively.
Spin transfer appears to be a promising tool for improving spintronics devices. Experiments that quantitatively access the magnitude of the spin transfer are required for a fundamental understanding of this phenomenon. By inductively measuring spin waves propagating along a permalloy strip subjected to a large electrical current, we observed a current-induced spin wave Doppler shift that we relate to the adiabatic spin transfer torque. Because spin waves provide a well-defined system for performing spin transfer, we anticipate that they could be used as an accurate probe of spin-polarized transport in various itinerant ferromagnets.
We report a complete study of spin-wave transduction combining microwave measurements performed over a frequency range of ͓1-15͔ GHz on Permalloy strips ͑thickness= 10-20 nm, width=2-8 m͒ and an accurate modeling of the experiment. This technique has been used recently to assess the spin polarization of the electrical current by measuring a current-induced spin-wave Doppler shift. We present here an electromagnetism calculation based on the magnetostatic wave theory combined with the Gilbert form of the damping that can be used directly as an optimization tool for future spin-wave experiments.
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