DMI meter: Measuring the Dzyaloshinskii-Moriya interaction inversion in Pt/Co/Ir/Pt multilayers

TL;DR

This paper introduces a magnetic field-driven method to measure interfacial Dzyaloshinskii-Moriya interactions in multilayer thin films, enabling precise control and understanding of domain wall structures without electrical effects.

Contribution

The authors develop a novel, field-only measurement technique for DMI in multilayers, demonstrating DMI inversion via ultrathin Ir layers and highlighting interface atomic structure effects.

Findings

Reversal of DMI sign with Ir insertion

Continuous transition from right- to left-handed Néel walls

High sensitivity of DMI to interface atomic structure

Abstract

We describe a field-driven domain wall creep-based method for the quantification of interfacial Dzyaloshinskii-Moriya interactions (DMI) in perpendicularly magnetized thin films. The use of only magnetic fields to drive wall motion removes the possibility of mixing with current-related effects such as spin Hall effect or Rashba field, as well as the complexity arising from lithographic patterning. We demonstrate this method on sputtered Pt/Co/Ir/Pt multilayers with a variable Ir layer thickness. By inserting an ultrathin layer of Ir at the Co/Pt interface we can reverse the sign of the effective DMI acting on the sandwiched Co layer, and therefore continuously change the domain wall (DW) structure from right- to the left-handed N\'{e}el wall. We also show that the DMI shows exquisite sensitivity to the exact details of the atomic structure at the film interfaces by comparison with a symmetric epitaxial Pt/Co/Pt multilayer.