Coupling between electronic spins in rare earth doped Te-N and Bi-N cluster
s is investigated by size selective Stern-Gerlach deflection experiments. T
he results are interpreted in terms of Dy3+(Te-N)(3-) and Dy3+(Bi-N)(3-) st
ructures. This magnetochemical approach is consistent with a Zener type exc
hange spin coupling between valence electrons and the localized electrons i
n the impurity core.