Chiral domain wall dynamics in magnetic heterostructures with bulk Dzyaloshinskii-Moriya interactions

TL;DR

This paper systematically investigates the dynamics of chiral domain walls in magnetic heterostructures with bulk Dzyaloshinskii-Moriya interactions, revealing how external fields and material parameters influence wall motion and providing a method to measure DMI strength.

Contribution

It introduces a comprehensive analysis of domain wall behavior in non-centrosymmetric magnets with bulk DMI, including critical thresholds and velocity dependence, advancing understanding of chiral magnetic dynamics.

Findings

Dependence of Walker critical field and current density on bulk DMI and anisotropy ratio.

Parabolic velocity dependence on in-plane bias field beyond Walker breakdown.

Method to measure bulk DMI strength via domain wall displacement analysis.

Abstract

In this work, dynamics of chiral domain walls in long and narrow magnetic heterostructures based on non-centrosymmetric chiral magnets with bulk Dzyaloshinskii-Moriya interactions (DMI) and perpendicular magnetic anisotropy is systematically investigated. The driving forces can be out-of-plane magnetic fields and in-plane currents, correspondingly both steady and precessional flows are considered. Their dividing points (the Walker critical field and current density) are obtained as functions of bulk DMI strength ($D_{\mathrm{b}}$) and the ratio ($\kappa$) of total (crystalline plus shape) anisotropy in the hard axis over that in the easy one. When far beyond Walker breakdown, the dependence curve of wall velocity on external in-plane bias field takes parabolic shape around the compensation point where the total in-plane field disappears. The center shift is determined by $D_{\mathrm{b}}$, $\kappa$, and the wall's topological charge, thus can be used to measure the bulk DMI strength in chiral magnets.