Intrinsic magnetic moments of gold nanoparticles

Abstract

In this study the intrinsic magnetic moments developed in 4 nm bare fcc Au nanoparticles were investigated. The magnetization curves reveal a Langevin magnetic field profile, reflecting the existence of spontaneous magnetic moments. Neutron diffraction measurements detect a ferromagnetic moment. The magnetic diffraction patterns are consistent with a moment of $\ensuremath{\langle}{\ensuremath{\mu}}_{Z}\ensuremath{\rangle}=0.14$ \ensuremath{\mu}${}_{B}$ points in the crystallographic [111] direction at 5 K. Magnetostatic interparticle interactions weaken the localized magnetic moments but enhance the conduction electron density. These behaviors can be understood by considering the merging of the 5$d$ and 6$s$ electron bands triggered by finite-size effects and the lifting of band mixture by interparticle interactions.