Emergent impedance due to antiferromagnetic domain wall dynamics

TL;DR

This paper develops a theoretical framework to analyze emergent impedance caused by antiferromagnetic domain wall dynamics, revealing two distinct contributions affecting the electrical response.

Contribution

It introduces an analytical formalism for the electrical response of antiferromagnetic domain walls under ac currents, highlighting unique dynamical contributions.

Findings

Two dynamical modes influence emergent impedance: translational motion and sublattice canting.

The sign and magnitude of the impedance's imaginary part depend on the competition between these modes.

The results deepen understanding of electron transport in antiferromagnets and suggest new spintronics applications.

Abstract

We theoretically investigate emergent impedance induced by domain-wall dynamics in antiferromagnets. Emergent impedance, arising from a combined action of spin-transfer torque and spinmotive force, was previously predicted and observed in spiral magnets. Here we develop a formalism for the electrical response of an antiferromagnetic domain wall under ac currents, and obtain analytical expressions for the resulting emergent impedance. We find that two dynamical modes play separate roles in the emergent impedance: Translational motion of the domain-wall center generates a contribution proportional to its velocity, analogous to that arising from the corresponding motion of a spiral magnet. Another contribution, unique to antiferromagnetic domain walls, originates from the time-dependent canting of the sublattice magnetizations localized within the moving domain wall, whose magnitude is inversely proportional to the antiferromagnetic exchange coupling constant. The competition between these two distinct contributions determines the sign and magnitude of the imaginary part of the emergent impedance at sub-resonant frequencies. Our results provide a fundamental insight into electron transport in antiferromagnets, and open avenues for novel antiferromagnet-based spintronics devices.