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

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.

Self-assembly of Co/Pt stripes with current-induced domain wall motion towards 3D racetrack devices

“…This result led to the conclusion that SOT modulation is attributed to the extrinsic part. A similar effect was previously reported in a comparable material combination (double-layer Co/Pt) with an increase of 28.5% in a Co/Pt system on a Kapton film 62 .…”

“…As the applied strain is increased, the racetrack stripe gets narrower, consequently resulting in an increase in the metal’s resistivity. According to the discussion 62 , the heightened efficiency of SOT efficiency under elongation strain is attributed to extrinsic scattering. It was reported that in heavy metals, like Pt, Ta, W, Pd the intrinsic scattering typically dominates over the extrinsic.…”

Enhanced effective spin Hall efficiency contributed by the extrinsic spin Hall effect in Pt1- x Ta x /CoFeB structures

“…This effect can be considered an evolution of the SHE in electronic systems, which has a wide range of applications in precision metrology, quantum imaging, and micro-imaging [8]. In the FM/HM heterostructure, SOT originates from the bulk SHE and/or the interface Rashba-Edstein effect [9][10][11][12][13]. For SHE, the charge current flowing through the HM can be converted into a spin current due to the strong spin-orbit coupling (SOC).…”

“…For SHE, the charge current flowing through the HM can be converted into a spin current due to the strong spin-orbit coupling (SOC). The spin current is injected from the HM to the FM layer, and a torque is applied to the FM layer, which can switch the magnetization [1,13].…”

An Ultrathin Flexible Programmable Spin Logic Device Based on Spin–Orbit Torque

“…Logic-in-memory architectures provide a possible solution for future data storage and processing. Especially, spin logic devices based on spin–orbit torque (SOT) induced magnetization switching − show particular advantages in constructing logic-in-memory architectures with high computing capability, low power dissipation, − and good programming capability. , In 2020, Lim et al developed a reconfigurable SOT-driven logic device using a double Hall cross structure with an integrated bias field line for the generation of a local bias field . In 2022, Fan et al realized four different magnetic configurations in IrMn/Co/Ru/CoPt/CoO multilayers, which are programmable by magnetic field and current .…”