Enhanced Interfacial Dzyaloshinskii-Moriya Interaction in annealed Pt/Co/MgO structures

TL;DR

This paper demonstrates that thermal annealing of Pt/Co/X/MgO structures significantly enhances the interfacial Dzyaloshinskii-Moriya interaction, reaching values above 3 mJ/m^2, which is promising for skyrmion-based spintronic devices.

Contribution

It provides experimental evidence and theoretical understanding of how annealing and atomic layer insertion enhance iDMI in ultra-thin magnetic films.

Findings

iDMI constant up to 3.3 mJ/m^2 achieved

Annealing improves MgO crystallization and increases iDMI

Atomically thin Ta and Mg insertions enhance iDMI

Abstract

The interfacial Dzyaloshinskii-Moriya interaction (iDMI) is attracting great interests for spintronics. An iDMI constant larger than 3 mJ/m^2 is expected to minimize the size of skyrmions and to optimize the DW dynamics. In this study, we experimentally demonstrate an enhanced iDMI in Pt/Co/X/MgO ultra-thin film structures with perpendicular magnetization. The iDMI constants were measured using a field-driven creep regime domain expansion method. The enhancement of iDMI with an atomically thin insertion of Ta and Mg is comprehensively understood with the help of ab-initio calculations. Thermal annealing has been used to crystallize the MgO thin layer for improving tunneling magneto-resistance (TMR), but interestingly it also provides a further increase of the iDMI constant. An increase of the iDMI constant up to 3.3 mJ/m^2 is shown, which could be promising for the scaling down of skyrmion electronics.