Field-free spin-orbit torque switching enabled by interlayer Dzyaloshinskii-Moriya interaction

TL;DR

This paper demonstrates field-free spin-orbit torque switching in simple Pt/Co multilayer structures enabled by interlayer Dzyaloshinskii-Moriya interaction, advancing practical SOT-MRAM technology.

Contribution

It reveals the intrinsic interlayer DMI in Pt/Co structures and utilizes it for field-free magnetization switching with a novel current orientation.

Findings

Achieved field-free SOT switching using interlayer DMI.

Demonstrated switching in both multilayer and synthetic antiferromagnetic structures.

Proposed a new pathway for practical SOT-MRAM devices.

Abstract

Perpendicularly magnetized structures that are switchable using a spin current under field-free conditions can potentially be applied in spin-orbit torque magnetic random-access memory(SOT-MRAM).Several structures have been developed;however,new structures with a simple stack structure and MRAM compatibility are urgently needed.Herein,a typical structure in a perpendicular spin-transfer torque MRAM,the Pt/Co multilayer and its synthetic antiferromagnetic counterpart with perpendicular magnetic anisotropy, was observed to possess an intrinsic interlayer chiral interaction between neighboring magnetic layers,namely the interlayer Dzyaloshinskii-Moriya interaction (DMI) effect. Furthermore, using a current parallel to the eigenvector of the interlayer DMI, we switched the perpendicular magnetization of both structures without a magnetic field, owing to the additional symmetry-breaking introduced by the interlayer DMI. This SOT switching scheme realized in the Pt/Co multilayer and its synthetic antiferromagnet structure may open a new avenue toward practical perpendicular SOT-MRAM and other SOT devices.