Magnetic assembles of FePt (001) nanoparticles with SiO2 addition

Isolated FePt (001) nanoparticles surrounded with amorphous SiO2 have been fabricated by electron beam evaporation onto MgO (001) single-crystal substrates via the introduction of a SiO2 intermediate layer into the FePt film structures. The formation of two-dimensional magnetic assemblies of ordered FePt (001) nanoparticles with an average size of about 6 nm was directly obtained with this process at only 400 degrees C due to the interpenetration of SiO2, which has a lower surface energy. Studies of angular dependent coercivity show a tendency of a domain-wall motion to weaken toward rotation of reverse-domain type upon thickness of SiO2 additive layer into the FePt film structures. On the other hand, the exchange coupling between neighboring particles in the FePt nanostructures could be reduced with ultrathin SiO2 addition, which is confirmed from the Kelly-Henkel (delta M) plot. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3058690]