Spin Hall angle quantification from spin pumping and microwave photoresistance

Abstract

We present a method to quantify the spin Hall angle (SHA) with spin pumping and microwave photoresistance measurements. With this method we separate the inverse spin Hall effect (ISHE) from other unwanted effects for permalloy/Pt bilayers using out-of-plane microwave excitation. Through microwave photoresistance measurements, the in- and out-of-plane precessing angles of the magnetization are determined and enabled for the exact determination of the injected pure spin current. This method is demonstrated with an almost perfect Lorentz line shape for the obtained ISHE signal and the frequency independent SHA value as predicted by theory. By varying the Pt thickness, the SHA and spin-diffusion length of Pt is quantified as $0.012\ifmmode\pm\else\textpm\fi{}0.002$ and $8.3\ifmmode\pm\else\textpm\fi{}0.9$ nm, respectively.