Expression for hysteresis loss of immobilized magnetic nanoparticles in a wide range of particle parameters and excitation conditions: Parameter optimization for hyperthermia application

Hysteresis loss of magnetic nanoparticles (MNPs) has been widely studied for magnetic-hyperthermia application. On the basis of the numerical simulation for the AC magnetization curve of immobilized MNPs, we obtain an analytical expression for the hysteresis loss that is applicable to a wide range of MNP parameters and excitation conditions. This expression is more general and includes the previously obtained ones. It can be used to quantitatively study how MNP parameters and excitation conditions affect the hysteresis loss. We also use the expression to show an optimization method for hyperthermia application. First, the MNP core size that maximizes the loss is obtained as a function of the excitation conditions. For the optimum core size, the expression for the loss becomes very simple, and we can quantitatively evaluate the loss. Then, a numerical example is shown in which we obtain a condition that yields a loss as large as 1 kW/g Fe. We also discuss the hysteresis loss of MNPs suspended in liquid. The obtained results will be useful for hyperthermia application.