Size-composition-dependent magnetic properties of metastable Fe-Pt nanocrystal prepared by ion beam mixing

Metastable nanocrystalline phases (MNCPs) of the Fe1−xPtx alloy are prepared by ion beam mixing and the magnetic properties of the obtained fcc structured MNCPs are investigated. It reveals that the alloy composition and the grain size could significantly affect the atomic magnetic moment (AMM) and that the alloy composition plays a decisive role in influencing the AMM of the fcc structured MNCPs and at an equatomic stoichiometry of Fe and Pt, the AMM reaches a peak value. A shell-core model is proposed and it could well explain the positive proportion between the AMM and the grain size observed in the experiments.