Interstitial Manganese

Some articles on manganese:

Gallium Manganese Arsenide - Growth
... In (Ga,Mn)As the manganese substitute into gallium sites in the GaAs crystal and provide a magnetic moment ... Because manganese has a low solubility in GaAs, incorporating a sufficiently high concentration for ferromagnetism to be achieved proves challenging ... However, if a large flux of manganese is used in these conditions, instead of being incorporated, segregation occurs where the manganese accumulate on the surface and form complexes ...