Fabrication of Fe-Fe3O4 Co-Aggregated Nanoparticles Assembly and Their AC Magnetic Property

Electromagnetic wave absorbers for low-frequency kHz ranges have attracted much attention due to electromagnetic wave inference problems. In this study, we fabricated co-aggregated assemblies of Fe and Fe3O4 nanoparticles (NPs) as a new candidate for electromagnetic wave shielding and absorbing materials. The co-aggregated assemblies with a mass ratio of Fe to Fe3O4 NPs of 5:5 showed a maximum magnetic loss (tan $\delta $ ) value of 0.023 at around 200 K. This can be explained by the blocking of magnetically isolated Fe NPs in the co-aggregated assembly, where the magnetostatic dipole interactions between the Fe NPs and the Fe and Fe3O4 NPs can be negligibly small.