Unidirectional Magnon-Driven Domain Wall Motion Due to the Interfacial Dzyaloshinskii-Moriya Interaction

TL;DR

This paper reports a novel unidirectional motion of magnetic domain walls driven by magnons, caused by interfacial asymmetry, which is a significant departure from previous bidirectional behaviors.

Contribution

The study introduces a new mechanism for unidirectional domain wall motion driven by magnons due to interfacial Dzyaloshinskii-Moriya interaction, supported by symmetry analysis and simple analytic theory.

Findings

Domain walls move unidirectionally regardless of magnon flow direction

Interfacial asymmetry causes dominant odd-order contributions

Analytic theory explains the counterintuitive unidirectional motion

Abstract

We demonstrate a unidirectional motion of a quasiparticle without an explicit symmetry breaking along the space-time coordinate of the particle motion. This counterintuitive behavior originates from a combined action of two intrinsic asymmetries in the other two directions. We realize this idea with the magnon-driven motion of a magnetic domain wall in thin films with interfacial asymmetry. Contrary to previous studies, the domain wall moves along the same direction regardless of the magnon-flow direction. Our general symmetry analysis and numerical simulation reveal that the odd order contributions from the interfacial asymmetry is unidirectional, which is dominant over bidirectional contributions in the realistic regime. We develop a simple analytic theory on the unidirectional motion, which provides an insightful description of this counterintuitive phenomenon.