Simple and fast evaluation of relaxation parameters of magnetic nanoparticles

The efficacy of magnetic hyperthermia treatment depends on the optimal available magnetic nanoparticles (MNPs) that are excited in a given alternating magnetic field and viscosity of the region of interest. In this regard, assessing the relevant relaxation parameters is of upmost importance and could improve the speed of development of efficient applications. Here, we demonstrate how to deduce all relevant magnetic parameters from fast, independent, and simple experimental measurements such as dynamic light scattering, vibrating sample magnetometer, and lock-in thermography. We study the thermal behaviour of two MNPs with different forms, i.e. spherical and cubical, synthesized in-house by thermal decomposition and coated with 4 different surface agents. By determination of specific absorption rate (SAR) values, hydrodynamic diameters and M- H curves it is possible to compute the magnetic particle volume, dominant relaxation time and magnetocrystalline anisotropy constant. The calculated SAR values derived from these parameters, show good agreement with the experimental determined SAR data, demonstrating the applicability of the reported procedure. Additionally, our results indicate that surface coatings can have minor impacts on the thermal dissipation of Neel relaxation dominated MNPs.