The interfacial Dzyaloshinskii-Moriya interaction and spin-orbit torque driven domain wall motion in Co/Ni multi-layers with a Ptx(Ir,Au)1−x seedlayer

D Lau,V Sokalski

doi:10.1063/1.5079825

Abstract

We use Kerr microscopy to characterize magnetic domain walls in Co/Ni based magnetic nanowires grown on a Pt seedlayer with a thin Ptx(Ir,Au)1−x buffer layer. The buffer layer composition enables control of the interfacial DMI vector as measured from the asymmetric bubble expansion technique while the thicker Pt seedlayer is expected to govern the spin Hall angle. Additions of either Ir or Au to the Pt buffer layer give rise to a marked drop in the interfacial DMI vector. The efficiency of current induced magnetic domain wall motion in nanowires shows a direct relation to DMI across the composition spectrum. This correlation is discussed in the context of future spintronic devices as a mechanism for engineering the spin-orbit coupling properties of complex magnetic multi-layers.

Highlights

The union of strong spin-orbit coupling in 5d heavy metals and conventional ferromagnetism in 3d transition metals has lead to new spin phenomena in complex magnetic multi-layers
We have previously have shown that alloying a Pt buffer layer with Ir leads to a monotonic reduction of the interfacial DMI vector measured from the asymmetric expansion of magnetic bubble domains
The values of DMI were extracted from experimental measurements of velocity vs field using the augmented dispersive stiffness model, which accounts for contributions from a chiral-damping like effect

Summary

INTRODUCTION

The union of strong spin-orbit coupling in 5d heavy metals and conventional ferromagnetism in 3d transition metals has lead to new spin phenomena in complex magnetic multi-layers. This includes the interfacial Dzyaloshinskii-Moriya interaction, which is well-established to stabilize chiral magnetic domain walls and Skyrmions with the Néel-type configuration, and the spin Hall effect that enables their efficient manipulation with electric current.. Having validated the experimental methodology, this work serves to expand the heavy metal composition space for controlling interfacial DMI and directly measure its impact on the efficiency of current-induced domain wall motion

EXPERIMENTAL TECHNIQUES

RESULTS AND DISCUSSION

SUMMARY