Electric manipulation of domain walls in magnetic Weyl semimetals via the axial anomaly

TL;DR

This paper demonstrates how the axial anomaly in magnetic Weyl semimetals enables electric control of domain wall chirality and dynamics, providing a novel mechanism for spintronic device manipulation.

Contribution

It introduces a method to manipulate domain walls via the axial anomaly, linking electric fields to magnetic textures in Weyl semimetals.

Findings

Electric fields induce a spin torque through the axial anomaly.

Electric control can delay Walker breakdown in domain walls.

Quantum fluctuations enhance domain wall velocities.

Abstract

We show how the axial (chiral) anomaly induces a spin torque on the magnetization in magnetic Weyl semimetals. The anomaly produces an imbalance in left- and right-handed chirality carriers when non-orthogonal electric and magnetic fields are applied. Such imbalance generates a spin density which exerts a torque on the magnetization, the strength of which can be controlled by the intensity of the applied electric field. We show how this results in an electric control of the chirality of domain walls, as well as in an improvement of the domain wall dynamics, by delaying the onset of the Walker breakdown. The measurement of the electric field mediated changes in the domain wall chirality would constitute a direct proof of the axial anomaly. Additionally, we show how quantum fluctuations of electronic Fermi arc states bound to the domain wall naturally induce an effective magnetic anisotropy, allowing for high domain wall velocities even if the intrinsic anisotropy of the magnetic Weyl semimetal is small.