Doping quantum dots (QDs) with manganese is topical due to the magnetic interactions of the individual Mn(2+) ions and the semiconductor exciton. Characterizations of doped materials prepared using traditional methods is hampered due to inhomogeneous doping due to Poisson statistics, as some QDs have no dopants, some have one ion, etc. This problem can be addressed through the production of exactly doped nanomaterials whereby nucleation of the QDs is realized by seeding with organometallic clusters. Here Mn4Te4(SC3H7)4 clusters have been applied to synthesize (MnTe)4:CdSe quantum dots and (MnTe)4:ZnCdSe nanowires. Initial characterizations of the QDs were surprising as no magnetic behavior was observed. Further studies revealed that multiple manganese ions in each QD are in close contact and are antiferromagnetically coupled, which obliviates their magnetic behavior. In contrast strong signals were observed in (MnTe)4:ZnCdSe wires, which could be due to ferromagnetic coupling of the Mn(2+) ions. These initial findings are augmented with DFT calculations on large (Mn2Te)(Cd145Se146)(ZnCl2)29 model clusters that reveal that the two magnetic phases are nearly degenerate in cadmium chalcogenide nanoparticles.

Programmable ferromagnetic and antiferromagnetic coupling in manganese doped semiconductor nanoparticles via the cluster seed method

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