Dipolar interactions in magnetic nanowires aggregates

TL;DR

This study demonstrates that dipolar interactions in dense magnetic nanowire aggregates minimally affect coercivity, supporting their use in permanent magnetic materials.

Contribution

It provides experimental and simulation evidence that dipolar interactions do not significantly reduce coercivity in dense nanowire composites.

Findings

Dipolar interactions are not detrimental to high coercivity.

Misalignment reduces coercivity by only 30%.

Dipolar effects are sensitive to wire arrangement.

Abstract

We investigate the role of dipolar interactions on the magnetic properties of nanowires aggregates. Micromagnetic simulations show that dipolar interactions between wires are not detrimental to the high coercivity properties of magnetic nanowires composites even in very dense aggregates. This is confirmed by experimental magnetization measurements and Henkel plots which show that the dipolar interactions are small. Indeed, we show that misalignment of the nanowires in aggregates leads to a coercivity reduction of only 30%. Direct dipolar interactions between nanowires, even as close as 2 nm, have small effects (maximum coercivity reduction of ~15%) and are very sensitive to the detailed geometrical arrangement of wires. These results strenghten the potential of magnetic composite materials based on elongated single domain particles for the fabrication of permanent magnetic materials.