We show that CdMnTe self-assembled quantum dots can be formed by depositing a submonolayer of Mn ions over a ZnTe surface prior to deposition of the CdTe dot layer. Single dot emission lines and strongly polarized quantum dot photoluminescence in an applied magnetic field confirm the presence of Mn in individual quantum dots. The width of PL lines of the single CdMnTe dots is 3 meV due to magnetic moment fluctuations of the Mn ions. After rapid thermal annealing, the emission lines of individual magnetic quantum dots narrow significantly to 0.25 meV showing that effect of magnetic fluctuations is strongly reduced most probably due to an increase in the average quantum dot size. These results suggest a way to tune the spin properties of magnetic quantum dots.
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