Self-organized magnetic assemblies of (001) oriented FePt nanoparticles with SiO₂additive

Abstract

Well-isolated FePt(001) nanoparticles embedded in an amorphous SiO2 matrix have been successfully fabricated via a molecular-beam epitaxy technique on MgO(001) single-crystal substrates via the introduction of a SiO2 intermediate layer into the FePt film structures, the critical thickness of which is 10?nm. 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??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 shift towards rotation of reverse-domain type upon insertion of the SiO2 into the FePt structures, and domain rotation is enhanced, leading to a decoupling of intergrain interaction, as identified with ?M measurement.