Exact Solution for Current-Driven Domain-Wall Dynamics Beyond Lorentz Contraction in Antiferromagnets with Dzyaloshinskii-Moriya Interaction

TL;DR

This paper presents an exact analytical solution for current-driven domain-wall dynamics in antiferromagnets with Dzyaloshinskii-Moriya interaction, revealing unique behaviors like constant velocity and unconventional width changes.

Contribution

It provides the first exact solution for spiral domain-wall dynamics in antiferromagnets with DMI, applicable to various DW configurations and predicting novel behaviors.

Findings

DW velocity is constant under nonadiabatic spin-transfer torque.

DW width can elongate or contract depending on damping and torque.

DMI modifies DW dynamics, producing experimentally detectable signatures.

Abstract

We study current-driven domain-wall (DW) dynamics in antiferromagnets (AFMs) with Dzyaloshinskii-Moriya interaction (DMI). We obtain an exact analytical solution for spiral DW dynamics, applicable to both head-to-head DWs under bulk DMI and up-down DWs under interfacial DMI when the magnetic easy axis is aligned with the DMI vector. For the latter case experimentally relevant to synthetic AFMs with in-plane anisotropy, the solution predicts a constant DW velocity driven by nonadiabatic spin-transfer torque together with a steady rotation of the DW tilt angle induced by damping-like spin-orbit torque. Remarkably, the DW width shows unconventional current dependence, either pure elongation or contraction followed by elongation depending on damping and torque parameters, in sharp contrast to the Lorentz-type contraction known for antiferromagnetic (AF) DWs without DMI. These results provide an exact description of current-driven AF-DW dynamics and suggest experimentally accessible signatures of DMI-modified DW dynamics in synthetic AFMs.