Emergent electric field induced by dissipative sliding dynamics of domain walls in a Weyl magnet

TL;DR

This paper investigates how dissipative sliding of magnetic domain walls in a Weyl semimetal generates an emergent electric field, revealing new insights into topological defect electrodynamics and potential applications in spintronics.

Contribution

It demonstrates that dissipative domain wall motion under oscillatory currents produces an emergent electric field, with experimental imaging and simulations highlighting the dominance of sliding over spin tilting.

Findings

Dissipative domain wall motion induces a measurable emergent electric field.

Domain wall sliding dominates over spin tilting in dynamics.

Strong domain wall scattering observed in NdAlSi devices.

Abstract

The dynamic motion of topological defects in magnets induces an emergent electric field, as exemplified by the continuous flow of skyrmion vortices. However, the electrodynamics underlying this emergent field remains poorly understood. In this context, magnetic domain walls - one dimensional topological defects with two collective modes, sliding and spin tilt - offer a promising platform for exploration. Here, we demonstrate that the dissipative motion of domain walls under oscillatory current excitation generates an emergent electric field. We image domain patterns and quantify domain wall length under applied magnetic fields in mesoscopic devices based on the magnetic Weyl semimetal NdAlSi. These devices exhibit exceptionally strong domain wall scattering and a pronounced emergent electric field, observed in the imaginary component of the complex impedance. Spin dynamics simulations reveal that domain wall sliding dominates over spin tilting, where the phase delay of the domain wall motion with respect to the driving force impacts the emergent electric field. Our findings establish domain-wall dynamics as a platform for studying emergent electromagnetic fields and motivate further investigations on the coupled motion of magnetic solitons and conduction electrons.