Structure and magnetic properties of (GaAs)nMnm and (GaAs)nFem clusters

The electronic and geometrical structures of (GaAs)nMnm and (GaAs)nFem clusters (for m = 1, n = 2–4, for m = 2, n = 1–4, and for m = 3, n = 4) are studied using density functional theory with generalized gradient approximation. The clusters are found to possess a large number of isomers that are close in total energy. For the clusters with multiple metal atoms, the ferromagnetic and antiferromagnetic couplings of the excess spin densities at the metal sites are close in energy. (GaAs)2Mn2, (GaAs)3Mn2, and (GaAs)4Mn3 have antiferromagnetic ground states, while all of the Fen-containing species, GaAsMn2 and (GaAs)4Mn2 have ferromagnetic ground states.