Field induced ordering in paramagnetic suspensions

The onset of magnetic-field-induced ordering in paramagnetic suspensions has been investigated by a Monte Carlo method and by study of the pair potential. The form of the variation of ordering field with particle radius is predicted, and a method of calculating the ordering field without a full many-body calculation is suggested. It must be noted that the systems studied by the Monte Carlo method were of relatively low packing fraction, and that in more densely packed systems, deviations from the pair potential approach may be more significant.