Model of interactions in nanometric particles of Barium hexaferrite

H. R. BERTORELLO; P. G. BERCOFF; M. I. OLIVA

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Año: 2004 vol. 269 p. 122 - 130

0304-8853

Magnetic interactions in nanostructured Ba hexaferrite systems with partially coupled particles are studied. In this kind of systems, there are regions with lower effective magnetic anisotropy Keff where nucleation of magnetization reversal occurs. The Preisach distribution functions were measured for samples with different irreversible susceptibility behavior. Several peaks in the Preisach distributions were identified and were associated with different particle clusters. The coercive fields of these clusters were associated with Keff : A model was developed linking Keff with the exchange-coupled volume (b) between two neighboring particles and the number of particles in clusters. The behavior that followed the best physical interpretation led to conclude that magnetization reversal starts in the exchange-coupled volume b between two neighboring particles and then propagates to the rest of the particle.