Ultrafast depinning of domain wall in notched antiferromagnetic nanostructures

TL;DR

This paper theoretically investigates the ultrafast depinning of antiferromagnetic domain walls at notches, revealing a strong dependence on damping and demonstrating depinning speeds much faster than ferromagnetic systems.

Contribution

It introduces a one-dimensional model explaining AFM domain wall depinning, highlighting the ultrafast dynamics and damping effects, which differ from ferromagnetic counterparts.

Findings

Depinning field depends on notch size and physical parameters.

Weak damping enhances domain wall depinning due to oscillations.

AFM domain walls depin three orders of magnitude faster than ferromagnetic ones.

Abstract

The pinning and depinning of antiferromagnetic (AFM) domain wall is certainly the core issue of AFM spintronics. In this work, we study theoretically the N\'eel-type domain wall pinning and depinning at a notch in an antiferromagnetic (AFM) nano-ribbon. The depinning field depending on the notch dimension and intrinsic physical parameters are deduced and also numerically calculated. Contrary to conventional conception, it is revealed that the depinning field is remarkably dependent of the damping constant and the time-dependent oscillation of the domain wall position in the weakly damping regime benefits to the wall depinning, resulting in a gradual increase of the depinning field up to a saturation value with increasing damping constant. A one-dimensional model accounting of the internal dynamics of domain wall is used to explain perfectly the simulated results. It is demonstrated that the depinning mechanism of an AFM domain wall differs from ferromagnetic domain wall by exhibiting a depinning speed typically three orders of magnitude faster than the latter, suggesting the ultrafast dynamics of an AFM system.