Coercivity Ageing Effect on FePt Nanoparticles in Mesoporous Silica via Stepwise Synthesis Strategy

FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy. A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature. For face-centered cubic (fcc) structured FePt nanoparticles, the ageing effect is sensitive to the pre-annealing temperature, especially when the temperature is close to the phase-transition. The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fcc and face-centered tetragonal structures, and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.