Spin orbit torques and Dzyaloshinskii-Moriya interaction in dual-interfaced Co-Ni multilayers

TL;DR

This study investigates how dual interfaces in Co-Ni multilayers influence spin orbit torque and Dzyaloshinskii-Moriya interaction, revealing their origins and effects on domain wall motion for spintronic applications.

Contribution

It demonstrates the manipulation of SOT and DMI through dual interfaces and clarifies their different origins, advancing understanding for spintronic device design.

Findings

SOT mainly originates from the bulk of heavy metals.

DMI is primarily interfacial in nature.

Domain wall motion direction depends on DMI and tilting angle.

Abstract

We study the spin orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) in the dual-interfaced Co-Ni perpendicular multilayers. Through the combination of top and bottom layer materials (Pt, Ta, MgO and Cu), SOT and DMI are efficiently manipulated due to an enhancement or cancellation of the top and bottom contributions. However, SOT is found to originate mostly from the bulk of a heavy metal (HM), while DMI is more of interfacial origin. In addition, we find that the direction of the domain wall (DW) motion can be either along or against the electron flow depending on the DW tilting angle when there is a large DMI. Such an abnormal DW motion induces a large assist field required for hysteretic magnetization reversal. Our results provide insight into the role of DMI in SOT driven magnetization switching, and demonstrate the feasibility of achieving desirable SOT and DMI for spintronic devices.