Correlation of magnetic and magnetothermal properties of ZnMn ferrite nanoparticles

The specific absorption rate of electromagnetic energy is the most important parameter to characterize the efficiency of the heating process during magnetic hyperthermia. Further improvements in the efficiency of converting electromagnetic energy into thermal energy are not possible without a deep understanding of the physical mechanisms of energy conversion and the development of new methods to increase SAR values. The purpose of this work is to experimentally investigate the dependence of the SAR value on the magnetic field amplitude of ZnMn ferrite magnetic nanoparticles (MNPs) and reveal the contribution of the non-zero hysteresis loop width to the heating of the MNPs. MNPs of ZnMn ferrite were obtained by chemical co-precipitation. Experimental studies conducted have shown that in large MNPs, the behavior of SAR values changes significantly with increasing electromagnetic field (EM) amplitude, which is related to the change in the rate of area increase. The hysteresis loop increases with increasing EM field amplitude. This allows us to conclude that the hysteresis heating mechanism dominates in large MNPs, and that MNPs larger than 13 nm are not less promising than small superparamagnetic particles (<10 nm). Considering the Brezovich limitation, choosing a field value at the 100 Oe level is more suitable for clinical practice using MNP data.