THE AGGREGATION MECHANISM OF SMALL MAGNETIC PARTICLE CHAINS

The aggregation mechanism of small ferromagnetic particle chains in viscous media is discussed. If we describe such chains as infinite uniformly magnetized cylinders, there will be no interchain interaction. It is shown that in the next approximation - chains of identical (i.e. spherical) particles - the interaction force decreases exponentially with the interchain distance (f approximately exp(- r/a), where a is the particle diameter), and hence this model cannot explain the strong aggregation of chains. However, the distribution of particle magnetic moments (resulting from size, shape etc. distributions) leads to an interaction, decreasing only as f approximately r-6 which can probably explain the observed phenomena.