The non-random walk of chiral magnetic charge carriers in artificial spin ice

K Zeissler,S K Walton,W R Branford,D E Read,T Tyliszczak,L F Cohen,S Ladak

doi:10.1038/srep01252

Abstract

The flow of magnetic charge carriers (dubbed magnetic monopoles) through frustrated spin ice lattices, governed simply by Coulombic forces, represents a new direction in electromagnetism. Artificial spin ice nanoarrays realise this effect at room temperature, where the magnetic charge is carried by domain walls. Control of domain wall path is one important element of utilizing this new medium. By imaging the transit of domain walls across different connected 2D honeycomb structures we contribute an important aspect which will enable that control to be realized. Although apparently equivalent paths are presented to a domain wall as it approaches a Y-shaped vertex from a bar parallel to the field, we observe a stark non-random path distribution, which we attribute to the chirality of the magnetic charges. These observations are supported by detailed statistical modelling and micromagnetic simulations. The identification of chiral control to magnetic charge path selectivity invites analogy with spintronics.

Highlights

The flow of magnetic charge carriers through frustrated spin ice lattices, governed by Coulombic forces, represents a new direction in electromagnetism
Artificial spin ice nanoarrays realise this effect at room temperature, where the magnetic charge is carried by domain walls
A purely Coulombic model, in which the field required to switch a bar is described as the force required to separate a point charge of 62q from a oppositely charged vertex of charge jQj 5 q at an initial separation defined by the domain wall width, has been used successfully to describe the above discussed ice rule implications in artificial spin ice[8,9,20]

Summary

Introduction

The flow of magnetic charge carriers (dubbed magnetic monopoles) through frustrated spin ice lattices, governed by Coulombic forces, represents a new direction in electromagnetism. A purely Coulombic model, in which the field required to switch a bar is described as the force required to separate a point charge of 62q (the ferromagnetic domain wall) from a oppositely charged vertex of charge jQj 5 q at an initial separation defined by the domain wall width, has been used successfully to describe the above discussed ice rule implications in artificial spin ice[8,9,20]. For this reason the switching tends to proceed by long cascades resulting from the nucleation of a few walls which each propagate right across the lattice (figure 1a)

Methods

Results

Conclusion