Doping of semiconductor nanocrystals by transition-metal ions has attracted tremendous attention owing to their nanoscale spintronic applications. Such doping is, however, difficult to achieve in low-dimensional strongly quantum confined nanostructures by conventional growth procedures. Here we demonstrate that the incorporation of manganese ions up to 10% into CdSe quantum nanoribbons can be readily achieved by a nucleation-controlled doping process. The cation-exchange reaction of (CdSe) 13 clusters with Mn 2+ ions governs the Mn 2+ incorporation during the nucleation stage. This highly efficient Mn 2+ doping of the CdSe quantum nanoribbons results in giant exciton Zeeman splitting with an effective g-factor of 600, the largest value seen so far in diluted magnetic semiconductor nanocrystals. Furthermore, the sign of the s-d exchange is inverted to negative owing to the exceptionally strong quantum confinement in our nanoribbons. The nucleation-controlled doping strategy demonstrated here thus opens the possibility of doping various strongly quantum confined nanocrystals for diverse applications.
Bibliographical noteFunding Information:
We would like to thank the National Creative Research Initiative Program (T.H. and J.P.) and the World Class University Program (T.H. and J.P.) of the Korean Ministry of Education, Science and Technology, the US National Science Foundation (J.K.F.) and the Robert A. Welch Foundation (G.S.H.) for financial support. We gratefully acknowledge the Texas Advanced Computing Center for use of their computing resources. We thank M.-S. Won in Korea Basic Science Institute for the EPR characterization. We also thank K. Ando for the preliminary study on MCD. J.H.Y. has benefited from a Seoul Science Fellowship.