Dragging of magnetic domain walls by interlayer exchange

TL;DR

This paper investigates how interlayer exchange coupling influences the dynamics of magnetic domain walls driven by spin-polarized currents, revealing correlated motion and suppression of Walker breakdown, with implications for spintronic devices.

Contribution

It introduces the effect of interlayer exchange coupling on the motion of separated magnetic domain walls under spin currents, a novel aspect in domain wall dynamics research.

Findings

Interlayer exchange coupling can induce correlated motion of domain walls.

Suppression of Walker breakdown occurs with increased domain wall velocity.

The dynamics depend strongly on current density, interlayer coupling, and pinning potential.

Abstract

Magnetic domain walls can be moved by spin-polarized currents due to spin-transfer torques. This opens the possibility to use them in spintronic memory devices as, e.g., in racetrack storage. Naturally, in miniaturized devices domain walls can get very close to each other and affect each others dynamics. In this work we consider two separated domain walls in different layers which interact via an interlayer exchange coupling. One of these walls is moved by a spin-polarized current. Depending on several parameters as the current density, the interlayer coupling or the pinning potential, the combined dynamics of the two domain walls can change very strongly allowing, e.g., for a correlated motion of the walls. In addition, more subtle effect appear as a suppression of the Walker breakdown accompanied by an increase of the domain wall velocity.