Experimental and computational investigation of the magnetic susceptibility of composite soft materials

The magnetic properties of densely packed composite granular materials are strongly affected by interactions between the grains. This paper addresses the influence of the interactions, as a function of the packing density, on the initial susceptibility. Our calculations are based on systems with rea listic physical microstructures which are free from an artificially imposed lattice. The introduction of particle elongation via demagnetizing factors due to prolate spheroids is shown to enhance the susceptibility and give r esults which are in good agreement with experimental observations of compos ite soft materials prepared by dispersing large Fe particles in a non-magne tic matrix.