Determination of intrinsic spin Hall angle in Pt

TL;DR

This paper measures the intrinsic spin Hall angle in platinum using spin torque ferromagnetic resonance, accounting for NiFe thickness and spin diffusion, and finds it to be approximately 0.068 at room temperature.

Contribution

It introduces a method to accurately determine the intrinsic spin Hall angle in Pt by considering NiFe thickness dependence and spin diffusion effects.

Findings

Intrinsic spin Hall angle of Pt is approximately 0.068 at room temperature.

The spin Hall angle remains nearly constant between 13 K and 300 K.

Spin diffusion in NiFe influences the measured spin Hall angle.

Abstract

The spin Hall angle in Pt is evaluated in Pt/NiFe bilayers by spin torque ferromagnetic resonance (ST-FMR) measurements, and is found to increase with increasing the NiFe thickness. To extract the intrinsic spin Hall angle in Pt by estimating the total spin current injected into NiFe from Pt, the NiFe thickness dependent measurements are performed and the spin diffusion in the NiFe layer is taken into account. The intrinsic spin Hall angle of Pt is determined to be 0.068 at room temperature, and is found to be almost constant in the temperature range 13 - 300 K.