Giant Diamagnetism in AuFe Nanoparticles

Multifunctional Au_0.5Fe_0.5 alloy nanoparticles from a polyol process were investigated, showing the alloy nanostructures with the formation of a new phase and twin microstructures. Giant diamagnetism, on the order of -10^{- 2} emu g^-1 Oe^-1 , is observed in the zero-field cooled process of the nanoparticles, which is modeled in terms of the spin-orbital interactions tuned by the modified potential energy as a result of the shrinking dimension, peculiar disordered microstructure, and heterogeneous elemental composition.