Multimodal grain size distributions obtained from high-temperature magnetization curves: A thermodynamical approach to the role of anisotropy

Abstract

Although a common technique to obtain the grain size distribution of an ensemble of magnetic nanoparticles is to fit its high-temperature magnetization to a distribution of Langevin functions, the anisotropy at temperatures close to the blocking temperature produces spurious results. This effect is justified on the basis of a power expansion of the free energy of the system.