Dependence of Dzyaloshinskii-Moriya interaction on the oxygen coverage in Pt/Co/MOx trilayers

TL;DR

This study investigates how varying oxygen coverage at the Co/MOx interface affects the Dzyaloshinskii-Moriya interaction (DMI) in Pt/Co/MOx trilayers, revealing a maximum DMI at optimal oxygen levels and suggesting shared microscopic origins with magnetic anisotropy.

Contribution

It demonstrates that the Co/MOx interface significantly influences DMI and its dependence on oxygen coverage, providing new insights into interface engineering for magnetic properties.

Findings

DMI strength varies with oxygen coverage.

Maximum DMI occurs at optimal oxygen coverage.

DMI correlates with interface magnetic anisotropy energy Ks.

Abstract

We have studied the interfacial Dzyaloshinskii-Moriya interaction (DMI) in a series of Pt/Co/MOx (M=Al, Gd) trilayers in which the degree of oxidation of the top Co interface is varied. To access to reliable values of the DMI strength, we have used a method based on the measurement of the saturation velocity of field driven chiral N\'eel domain walls. We show that the effective DMI strength in the Pt/Co/MOx trilayers varies with the oxidation degree of the Co/MOx interface. This strongly suggests that the Co/MOx interface gives a distinct contribution to the total DMI, adding to that of the Pt/Co interface. The DMI presents a maximum for the oxygen coverage maximizing also the interface magnetic anisotropy energy Ks. This calls for common microscopic origins for the contributions of the Co/MOx interface to DMI and Ks.