Two-Level Model Description of Superparamagnetic Relaxation in Nanoferrites (Co,Zn)Fe₂O₄

Abstract

The process of superparamagnetic relaxation of ferrite nanoparticles (Co,Zn)Fe2O4 was observed with the Mssbauer spectroscopy (80-773 K) and described by a two-level relaxation model. Simultaneous fitting of the Mssbauer spectra for a wide range of temperatures enabled a clear evaluation of the theoretical model and also determination of the relaxation rate for each temperature. The analysis of temperature dependence of relaxation rate allowed to estimate an anisotropy constant for the studied ferrite.