Dynamics of superparamagnetic nanoparticle in viscous liquid in rotating magnetic field

Abstract

The dynamics of magnetic nanoparticle in a viscous liquid in rotating magnetic field has been studied by means of numerical simulation and analytical calculations. In the magneto- dynamics approximation three different modes of motion of the unit magnetization vector and particle director are distinguished depending on the rotating magnetic field frequency and amplitude. The specific absorption rate of a dilute assembly of superparamagnetic nanoparticles in rotating magnetic field is calculated by solving the Landau – Lifshitz stochastic equation for unit magnetization vector and stochastic equation for particle director. At elevated frequencies an optimal range of particle diameters is found where the specific absorption rate of an assembly in rotating magnetic field has a maximum. It is shown that for magnetic hyperthermia in rotating magnetic field it is preferable to use rotating magnetic fields of moderate amplitude, H 0 = 100 Oe, in the frequency range 400-600 kHz.