EFFECT OF INTERPARTICLE INTERACTIONS ON THE DYNAMICAL PROPERTIES OF γ-Fe₂O₃ NANOPARTICLES

The dynamical behavior of γ-Fe₂O₃ particles in a polymer having the same volume distribution and interparticle interactions of different strengths were studied by means of a.c. susceptibility measurements (5 < v < 10⁴ Hz) and Mössbauer spectroscopy. The blocking temperature measured by a.c. susceptibility increases with increasing interactions, and that measured by Mossbauer spectroscopy decreases. The energy barrier increases, unambiguously, in both cases, in agreement with our model based on a statistical calculation of the interaction energy for a disordered assembly of particles with volume distribution and easy axes in random directions.