Dynamics of domain walls motion driven by spin-orbit torque in antiferromagnets

TL;DR

This paper develops a micromagnetic model to analyze antiferromagnetic domain wall motion driven by spin-orbit torque, deriving analytical expressions for domain wall width and velocity, and revealing a nucleation mechanism limiting current in racetrack memory.

Contribution

It provides the first analytical expressions for antiferromagnetic domain wall dynamics driven by spin-orbit torque, validated by numerical simulations, and identifies a unique nucleation mechanism affecting device performance.

Findings

Analytical expressions for domain wall width and velocity match simulations.

Nucleation of domains from edges limits maximum current in antiferromagnetic racetracks.

Continuous domain nucleation differs from ferromagnetic racetrack behavior.

Abstract

Ultrafast dynamics of antiferromagnetic materials is an appealing feature for novel spintronic devices. Several experiments have shown that both, the static states and the dynamical behavior of the antiferromagnetic order, are strictly related to stabilization of domains and domain wall (DW) motion. Hence for a quantitative understanding of statics and dynamics of multidomain states in antiferromagnetic materials a full micromagnetic framework is necessary. Here, we use this model to study the antiferromagnetic DW motion driven by the spin-orbit torque. The main result is the derivation of analytical expressions for the DW width and velocity that exhibit a very good agreement with the numerical simulations in a wide range of parameters. We also find that a mechanism limiting the maximum applicable current in an antiferromagnetic racetrack memory is the continuous nucleation of the domains from the edge, which is qualitatively different from what is observed in ferromagnetic racetracks.