The characterisation of interaction effects in fine particle systems

Experimental methods and theoretical models that enable interaction effects in particulate systems to be examined are discussed. Two distinct regimes of behavior are considered. The weak interaction case is examined and it is shown that, in general, low-field susceptibility studies can be used to establish the effects of interactions only if care is taken to exclude other effects such as progressive blocking. The strong interaction regime is considered, and the use of remanence curves, χ_irr curves and the δ I(H) plot in the study of interaction effects is described. For both regimes, the use of numerical models in this area is reviewed