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 <mu(Z)> = 0.14 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 5d and 6s electron bands triggered by finite-size effects and the lifting of band mixture by interparticle interactions.
