Hyperthermic effect in magnetic nanoparticles in the presence of weak orientation fluctuations

Abstract

The problem of steady-state oscillation of a magnetically rigid particle in an AC field of arbitrary amplitude and frequency in the presence of weak orientation fluctuations (at zero temperature or for a large particle volume) has been solved. From the condition of solvability of the Fokker-Planck equation at low temperatures, a correct solution for the magnetization of the particle has been obtained. It is shown that the energy absorption over one period of the field (the area of the dynamic hysteresis loop of magnetization) in this case is always higher than for a loop with finite temperature. In other words, for magnetically rigid particles, thermal fluctuations always reduce their heat generation. This conclusion is important for the method of magnetic hyperthermia.