Continuous nucleation switching driven by spin-orbit torques

TL;DR

This paper demonstrates a method for continuous magnetic switching using spin-orbit torque in patterned magnetic strips, with potential applications in neuromorphic computing, by employing focused ion beam irradiation and a phenomenological model.

Contribution

It introduces a novel approach to achieve continuous SOT-driven switching via localized ion beam irradiation and provides a phenomenological model for current and field dependence.

Findings

Large in-plane field reduces nucleation barrier.

Focused ion beam enables localized softening and continuous switching.

The phenomenological model describes magnetization and nucleation domain dependence.

Abstract

Continuous switching driven by spin-orbit torque (SOT) is preferred to realize neuromorphic computing in a spintronic manner. Here we have applied focused ion beam (FIB) to selectively illuminate patterned regions in a Pt/Co/MgO strip with perpendicular magnetic anisotropy (PMA), soften the illuminated areas and realize the continuous switching by a SOT-driven nucleation process. It is found that a large in-plane field is a benefit to reduce the nucleation barrier, increase the number of nucleated domains and intermediate states during the switching progress, and finally flatten the switching curve. We proposed a phenomenological model for descripting the current dependence of magnetization and the dependence of the number of nucleation domains on the applied current and magnetic field. This study can thus promote the birth of SOT devices, which are promising in neuromorphic computing architectures.