Strain-Mediated Spin-Orbit Torque Enhancement in Pt/Co on Flexible Substrate.

Hwee Wong, Grayson Dao; Xu, Zhan; Gan, Weiliang; Ang, Calvin Ching Ian; Law, Wai Cheung; Tang, Jiaxuan; Zhang, Wen; Wong, Ping Kwan Johnny et al. · ACS Nano · 2021

basic_science · Level V

Where this comes from

Abstract

Current-induced magnetization switching by spin-orbit torque generated in heavy metals offers an enticing realm for energy-efficient memory and logic devices. The spin Hall efficiency is a key parameter in describing the generation of spin current. Recent findings have reported enhancement of spin Hall efficiency by mechanical strain, but its origin remains elusive. Here, we demonstrate a 45% increase in spin Hall efficiency in the platinum/cobalt (Pt/Co) bilayer, of which 78% of the enhancement was preserved even after the strain was removed. Spin transparency and X-ray magnetic circular dichroism revealed that the enhancement was attributed to a bulk effect in the Pt layer. This was further confirmed by the linear relationship between the spin Hall efficiency and resistivity, which indicates an increase in skew-scattering. These findings shed light on the origin of enhancement and are promising in shaping future utilization of mechanical strain for energy-efficient devices.