Magnetic materials particle/matrix interactions

Inorganic matrix can be used for magnetic nanoparticles assembly. Cobalt particles can be placed in the cellular structure of mesoporous silica [349]. The constraining in nanosize pores creates a special one-dimensional interaction between the magnetic material particles, resulting in increased coercivity. 

However, the run of the ZFC magnetization curve does not correspond to the results of TEM, EPR and IR spectroscopy results concerning particle size of y-Fe20j and the absence of its interaction with Si02 matrix. Thus, a wide maximum T ax at 145 K is typical of greater particles [1-2,4] as compared to the studied materials. A considerable distinction between T ax and Tsep (250 K) is the evidence of a wide particle size distribution. The mentioned contradictions between the particle size and magnetic behavior of the samples can be resolved considering that and T ep parameters depend not only on a particle size, but on a number of other features of materials like surface states, defectiveness of structure, cluster interaction [5]. 

In nanocomposites materials, an annealing process transforms a multilayered structure into non-magnetic matrix containing magnetic particles. Monodisperse and non-interacting particles were found to be promising to reduce noise and decay rates (Moser et al, 2002). 

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