Spin Hall Angle Quantification from Spin Pumping and Microwave Photoresistance

TL;DR

This paper introduces a novel method combining spin pumping and microwave photoresistance to accurately quantify the spin Hall angle in permalloy/Pt bilayers, effectively isolating the inverse spin Hall effect and determining key spin transport parameters.

Contribution

It presents a new approach that separates the inverse spin Hall effect from other effects and accurately measures the spin Hall angle and spin-diffusion length in platinum.

Findings

The spin Hall angle in Pt is quantified as 0.012.

The spin-diffusion length in Pt is measured as 8.3 nm.

The method yields a frequency-independent SHA value consistent with theory.

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 (0.001) and 8.3 (0.9) nm, respectively.