Dipolar Interactions and Size Distribution on Blocking Temperature NPs

Role of Dipolar Interactions and Volume Particle Size Distribution on the Nonmonotonic Magnetic Field Dependence of the Blocking Temperature in Magnetic Nanoparticles.
Sueli H. Masunaga, Renato F. Jardim, Marcos J. Correia, and Wagner Figueiredo
J. Phys. Chem. C 120, 765 (2016)

The nonmonotonic behavior of the magnetic field dependence H of the superparamagnetic blocking temperature T_B(H) (or T_max(H)) of an assembly of magnetic nanoparticles NPs was studied both experimentally and theoretically. We have combined the measurements of zero-field cooling ZFC magnetization curves under H performed on samples with increasing concentration of Ni nanoparticles and Monte Carlo simulations. As a result, we have found that increasing the strength of the dipolar interaction between granules and the occurrence of a very narrow width of a log-normal volume particle size distribution of the NPs suppress the nonmonotonic behavior of T_max(H).