Domain Wall Motion in Thin-Film Magnets/ Topological Insulator Junctions

TL;DR

This paper develops a theoretical framework for controlling domain wall motion in thin-film magnets coupled with topological insulators, highlighting electric field effects on stability, velocity, and chirality reversal mechanisms.

Contribution

It introduces a novel model describing how electric and magnetic fields influence domain wall dynamics in topological insulator-magnet junctions.

Findings

Electric field stabilizes chirality and prevents Walker breakdown.

Electric field enhances the terminal velocity of domain walls.

Chirality reversal can be achieved by tuning chiral currents with a weak magnetic field.

Abstract

We derive the equations of motion of a Domain Wall in a thin-film magnet coupled to the surface states of a Topological Insulator in the presence of of both an electric field along the Domain Wall and a magnetic field perpendicular to the junction. We show how the electric field acts as a chirality stabilizer holding off the appearance of Walker breakdown and enhancing the terminal velocity. We also propose a mechanism to reverse the Domain Wall chirality in a controllable manner by tuning the chiral current flowing through the Wall. An input from a weak perpendicular magnetic field is required in order to break the reflection symmetry that protects the degeneracy of the chirality vacuum.