Size-dependent magneto-optical effects in CdMnTe diluted magnetic quantum dots

We report on the growth and high spatial resolution magneto-photoluminescence of CdMnTe quantum dots embedded in a ZnCdTe matrix with Mn content of about 3%. The giant Zeeman spitting of excitonic emission coming from individual quantum dots and magnetization fluctuations inside them are studied in magnetic fields up to 7 T. We have found that the description of these effects requires the inclusion of antiferromagnetic Mn-Mn interaction in the considerations. Moreover, the values of the Zeeman shift are strongly related to the size of the dot. In particular, the higher spectral position of the line is, i.e., the smaller the dot, the smaller the Zeeman splitting that is observed. This effect is quantitatively explained with model calculations made under the assumption of magnetic polaron formation in diluted magnetic quantum dots and the presence of ion-ion exchange interaction.