Defect-Mediated Bulk Dzyaloshinskii-Moriya Interaction in Ferromagnetic Multilayer Thin Films

TL;DR

This paper reveals that defect-induced dislocations in symmetric multilayer thin films can generate bulk Dzyaloshinskii-Moriya interaction, which is crucial for advancing spintronic device development.

Contribution

It uncovers the atomic-level origin of bulk DMI in symmetric multilayers, highlighting defect-mediated dislocations as a key factor.

Findings

Enhanced DMI with increased sputter gas pressure

Dislocation distribution correlates with DMI strength

Bulk DMI significant even in weakly asymmetric multilayers

Abstract

The Dzyaloshinskii-Moriya interaction (DMI) in asymmetric multilayers is crucial for spintronics. However, it is also significant even in symmetric ones, and unveiling its atomic-level origin remains an issue. We use electron microscopy to propose defect-mediated bulk DMI in Pt/Co/Pt. We find an enhancement of the net DMI by increasing sputter gas pressure. The samples have a compositional gradient, but their compositional asymmetry is weak. Our analysis suggests that the asymmetric distribution of dislocations in the compositional gradient regions generates bulk DMI. Our results indicate the importance of bulk DMI in multilayers and could facilitate the development of spintronic devices.