Advanced method for reliable estimation of the spin-orbit torque efficiency in low coercive ferromagnetic multilayers

TL;DR

This paper introduces a new method to accurately estimate spin-orbit torque efficiency in low coercive ferromagnetic multilayers by analyzing domain wall positions, demonstrating enhanced SOT with W capping layers.

Contribution

A novel domain wall analysis method for SOT estimation that accounts for Oersted field distribution, improving accuracy in low coercive multilayer structures.

Findings

Effective SOT field of 0.03 in Ru/Co/Ru structure

W capping layer increases SOT efficiency fivefold

New estimation method improves reliability of SOT measurements

Abstract

An experimental study of current-induced magnetization reversal of the Ru/Co/Ru and Ru/Co/Ru/W structures was carried out. In the considered structures, due to the small value of the coercive force comparable in magnitude to the Oersted field and the SOT effect field, magnetization reversal is carried out by moving a domain wall parallel to the direction of current injection. For such a case, a new method for estimating the effective field of SOT based on the analysis of the domain wall position taking into account the distribution of the Oersted field was proposed. This method allowed determining the effective longitudinal field and the efficiency of SOT equal 0.03 in the quasi-symmetric Ru/Co/Ru structure. It was found that adding the W capping layer enhances the SOT effect by 5 times.