Error-Free and Current-Driven Synthetic Antiferromagnetic Domain Wall Memory Enabled by Channel Meandering

TL;DR

This paper introduces a novel multi-bit magnetic memory utilizing a meandering domain wall channel with precise pinning regions, achieving energy-efficient, field-free, and reliable domain wall motion through micromagnetic simulations.

Contribution

It presents a new multi-bit magnetic memory design with controlled domain wall motion, enhanced by synthetic antiferromagnetic layers for improved reliability and speed.

Findings

Two distinct pinning mechanisms enable different cell switching modes

Synthetic antiferromagnetic layers improve switching reliability and speed

Micromagnetic simulations validate the proposed memory design

Abstract

We propose a new type of multi-bit and energy-efficient magnetic memory based on current-driven, field-free, and highly controlled domain wall motion. A meandering domain wall channel with precisely interspersed pinning regions provides the multi-bit capability of a magnetic tunnel junction. The magnetic free layer of the memory device has perpendicular magnetic anisotropy and interfacial Dzyaloshinskii-Moriya interaction, so that spin-orbit torques induce efficient domain wall motion. Using micromagnetic simulations, we find two pinning mechanisms that lead to different cell designs: two-way switching and four-way switching. The memory cell design choices and the physics behind these pinning mechanisms are discussed in detail. Furthermore, we show that switching reliability and speed may be significantly improved by replacing the ferromagnetic free layer with a synthetic antiferromagnetic layer. Switching behavior and material choices will be discussed for the two implementations.