Magnetic excitations in maghemite nanoparticles - a pre-study

Hysteretic heating of ferro and ferrimagnetic nanoparticles holds promise in both cancer treatment (magnetic hyperthermia) and for providing efficient heating in industrial-scale reactors. A direct in-situ measurement of the temperature of the nanoparticles as they are exposed to high-frequency AC magnetic fields is however lacking. Here we propose a pre-study of the magnetic and lattice excitations in nanoparticulate maghemite in zero field and as a function of temperature. The aim is to identify characteristic features in the excitation spectrum. Under AC-field conditions, i.e. in a future experiment, these should in theory allow us to directly determine the nanoparticle temperature via the detailed balance factor in the cross-section.