  Recent experiments on Mn-doped ZnS nanocrystals have shown unusual
magnetization properties. We describe a nearest-neighbor Heisenberg exchange
model for calculating the magnetization ratios of these antiferromagnetically
doped crystals, in which the dopant atoms are distributed inhomogeneously
within the nanocrystal. This simple inhomogeneous doping model is capable of
reproducing the experimental results, and suggests that interior dopant atoms
are localized within the crystal.
