Spontaneous orbital magnetization of mesoscopic dipole dimers

TL;DR

This paper explores how orbital electron magnetism and dipolar interactions in gold nanoparticle dimers can induce spontaneous magnetic moments, explaining observed ferromagnetic behaviors in ensembles of such particles.

Contribution

It introduces a model combining orbital magnetism and dipolar interactions to explain spontaneous magnetization in gold nanoparticle dimers, a novel insight into nanoscale magnetic phenomena.

Findings

Spontaneous magnetic moments can arise in gold nanoparticle dimers.

Orbital paramagnetic susceptibility is key to magnetic ordering.

The model explains ferromagnetic behavior in nanoparticle ensembles.

Abstract

Ensembles of gold nanoparticles present a magnetic behavior which is at odds with the weakly diamagnetic response of bulk gold. In particular, an unusual ferromagnetic order has been unveiled by several experiments. Here we investigate if the combined effect of orbital magnetism of conduction electrons and interparticle dipolar interaction can lead to magnetic ordering. Using different model systems of interacting mesoscopic magnetic dipoles, together with a microscopic description of the electron dynamics within the nanoparticles, we find that a spontaneous magnetic moment may arise in dimers of metallic nanoparticles when the latter are characterized by a large orbital paramagnetic susceptibility.