Silicide formation and particle size growth in high-temperature-annealed, self-assembled FePt nanoparticles

L1(0) FePt nanoparticle assemblies consisting of a few layers of 4-nm-diameter particles, are a potential data storage medium beyond 1 Tbit/in(2). However, annealing at temperatures >500 degreesC is required to form the high anisotropy L1(0) phase. Recent studies have shown a substantial drop in magnetization for T-anneal>650 degreesC. We show that this reduction in magnetization is due to silicide formation as a result of a chemical reaction with the native oxide or Si substrate. We also show that full L1(0) ordering is established only after annealing at 725 degreesC for 60 min and note that particle agglomeration occurs under these conditions. (C) 2004 American Institute of Physics.