Inverse spin Hall effect in Ni81Fe19/normal-metal bilayers

The large spread of published values for spin Hall angles, even for the most studied normal-metal platinum, reflects the difficulty of investigating the inverse spin Hall effect. In this Rapid Communication we examine the inverse spin Hall effect and anisotropic magnetoresistance for different Ni81Fe19(Py)/normal-metal bilayers operated by spin pumping using a coplanar waveguide. Angle, frequency, and temperature dependent measurements show that spin pumping and the inverse spin Hall effect can be used to quantify spin Hall angles only when the anisotropic magnetoresistance as a parasitic voltage generating effect is avoided. In this case we obtain spin Hall angles of 0.12 and 0.011 for Pt and Au, respectively. Furthermore, these measurements can be used to determine the spin diffusion length of Pt as a function of temperature.