Insights into the Magnetic Properties of Single-Core and Multicore Magnetite and Manganese-Doped Magnetite Nanoparticles

Assembled magnetite nanoparticles with oriented attachment have been prepared to study the effect of autoassembling on their heating efficiency. Their magnetic properties have been compared with those corresponding to single-core particles, also prepared in this study. It has been found that not only particle size and shape are determinant factors on the magnetic behavior but also the interparticle interactions as well since they drastically modify the effective magnetic volume related to the magnitude of the superparamagnetic moment. The high values of the superparamagnetic moment observed for all of the samples in a broad temperature range are probably a consequence of the dipolar interactions. Moreover, the sample exhibiting both large anisotropy barriers and superparamagnetic moment at 300 K is the one presenting the largest SAR values. Therefore, the superparamagnetic behavior at room temperature together with the magnetic hardness seem to be key factors for the heat generation.