Characterization of Néel relaxation time in multicore magnetic nanoparticles

Magnetic nanoparticles are developed for the biomedical applications such as hyperthermia and magnetic particle imaging. Magnetic relaxation determines the performance of magnetic nanoparticles in these applications. The magnetic relaxation was divided into two types as the Néel relaxation and Brown relaxations. In this research, the magnetization response associated with the Néel relaxation was observed by applying a pulse magnetic field in magnetic nanoparticles of the multicore structure. The measured Neel relaxation were roughly divided into fast and slow responses. The slow response was dominant compared to the fast part, which is consistent with the distribution of the particle core size of measured magnetic nanoparticles. Elucidating the Néel relaxation time of magnetic nanoparticles guide the design of particles suitable for the biomedical applications and determines the optimal magnetic field conditions.