Excitonic spin dynamics in coupled quantum dots of diluted magnetic semiconductors

Spin-polarized exciton dynamics is studied in coupled quantum dots (QDs) of II-VI diluted magnetic semiconductors. In double QDs fabricated by electron-beam lithography, an efficient spin-injection process is demonstrated via spin-polarized exciton tunneling with the tunneling time of 500 ps. In high-density self-organized CdSe QDs, the exciton lifetime is shorter in smaller dots with higher energies, indicating the energy transfer and the correlation of wavefunctions. Circular polarization of excitonic photoluminescence is observed at 0 T with an opposite sign to that of the excited light and with the rise time of 50 ps.