Well-ordered L1-FePt nanoparticles synthesized by improved SiO2-nanoreactor method

It was found that the well-ordered L10 structure is formed in the FePt nanoparticles synthesized by the improved “SiO2-nanoreactor” method, whereas the previously employed annealing condition has suffered from the presence of the unconverted fcc-FePt nanoparticles which are superparamagnetic at room temperature. The L10-FePt nanoparticles prepared by this method showed a smooth hysteresis loop with no kink, and the room temperature coercivity reaches an extremely large value of 28kOe, even though the particle size is 6.7nm in diameter. The Mössbauer hyperfine parameters of the nanoparticles are very close to those of the bulk L10-FePt alloy, indicating that they possess magnetic moments comparable to the bulk even at the particle surface.