Transfer dynamics of spin-polarized excitons into semiconductor quantum dots

We study on the transfer dynamics of spin-polarized excitons into self-assembled quantum dots (QDs) of CdSe coupled with a diluted magnetic semiconductor (DMS) layer of ZnMnSe through a ZnSe barrier layer. A variation in the degree of circular polarization P of excitonic photoluminescence in the coupled QDs was observed between samples with different thicknesses (LB) of the non-magnetic barrier. Relatively high values of P (∼0.3) were obtained in the samples with LB=1 or 2 nm, and the time dependences of the P value indicate the spin-transfer dynamics. From the LB dependence of the spin-transfer time, the spin-transfer mechanism is discussed, namely spin-conserving energy transfer.