Dynamic binding of driven interfaces in coupled ultrathin ferromagnetic layers

TL;DR

This paper experimentally demonstrates dynamic binding of domain walls in coupled ferromagnetic layers, showing bound states with unique velocity-field responses that occur when individual wall velocities are similar, especially near zero field.

Contribution

It introduces the first experimental observation of dynamic interface binding in coupled ferromagnetic layers and models these states with a one-dimensional approach.

Findings

Bound states occur over broad field ranges.

Bound walls move at a common velocity.

Bound states are prominent as the field approaches zero.

Abstract

We demonstrate experimentally dynamic interface binding in a system consisting of two coupled ferromagnetic layers. While domain walls in each layer have different velocity-field responses, for two broad ranges of the driving field, H, walls in the two layers are bound and move at a common velocity. The bound states have their own velocity-field response and arise when the isolated wall velocities in each layer are close, a condition which always occurs as H->0. Several features of the bound states are reproduced using a one dimensional model, illustrating their general nature.