Monodisperse magnetite (Fe3 O4) nanoparticles (NPs) were synthesized and coated using a SiO2 shell with controlled thickness ranging from 3.0 to 20.0 nm. The temperature-dependent zero-field-cooled (ZFC) and field-cooled (FC) magnetizations of the 7.5 nm Fe3 O4 NPs with systematically increasing interparticle spacing were studied using the continuous and intermittent cooling protocol. The experimental evidence from dc magnetization and simulated ZFC/FC curves reveal that the increasing interparticle spacing modulated the collective magnetic behavior by effectively lowering the interparticle dipolar coupling, and for 7.5 nm Fe3 O4 NPs a noninteracting particle system formed with interparticle spacing above 31.5 nm.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)