How Gold nanoparticle acquires magnetism? - Formation of large orbital moment at the interface

TL;DR

This study investigates the origin of magnetism in gold nanoparticles, revealing that large orbital magnetic moments form at the interface with magnetic materials, enhancing overall magnetization.

Contribution

It demonstrates that magnetism in gold nanoparticles is due to interfacial effects, specifically the formation of large orbital magnetic moments at the Au/magnetic particle interface.

Findings

Magnetization increases when Au-NPs are incorporated into Fe3O4 medium.

Large orbital magnetic moments form at the Au/magnetic interface.

A transition from positive saturation magnetization to diamagnetism is observed.

Abstract

In this paper, we have tried to find out the origin of magnetism in Gold nanoparticles (Au- NPs). We observe that upon incorporating Gold nanoparticles (Au-NPs) in Fe3O4 nanoparticle medium the net magnetisation increases compared to the pure Fe3O4 nanoparticle medium. This increase of magnetization can be attributed to the large orbital magnetic moment formation at the Au/magnetic particle interface indicating that magnetism observed in Au-NPs is an interfacial effect. This interfacial effect has been supported by the observation of sudden transition from positive saturated magnetisation to a negative diamagnetic contribution as a function of magnetic field on citrate coated gold Au-NPs.