Stretched Exponential Change of Magnetic Weight of Magnetite Ferrofluid: Distribution of Energy Barrier for Agglomeration of Nanoparticles

Magnetic nanoparticles usually agglomerate reversibly under magnetic field. Magnetophoretic transport demonstrates the possibilities of the biomedical applications such as intercellular manipulation of magnetic nanoparticles for imaging or drug delivery. Magnetization of ferro fluid occurs by Neel and Brownian mechanism and aggregation of nanoparticles. We have recently reported the magnetization of magnetite ferro fluid studied by measuring the change of magnetic weight. The stretched exponential behaviors have been observed for the samples of different concentrations under various magnetic fields. When we study the transmission change of the fluid as like in Refs 2 and 12, the single or double exponential decay is observed, which suggests that the particle movement in the fluid is affected by diffusion but the structural relaxations of aggregates cause the stretched exponential dynamics