Articles by Margaret Dobrowolska in JoVE
Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing Daniel Webber1, Tristan de Boer1, Murat Yildirim1, Sam March1, Reuble Mathew1, Angela Gamouras1, Xinyu Liu2, Margaret Dobrowolska2, Jacek Furdyna2, Kimberley Hall1 1Department of Physics and Atmospheric Science, Dalhousie University, 2Department of Physics, University of Notre Dame The technique of femtosecond four-wave mixing is described, including spectrally-resolved and time-resolved configurations. We illustrate the utility of this technique for the investigation of crucial physical properties in the III-V diluted magnetic semiconductors, afforded by its nonlinearity and high temporal resolution.
Other articles by Margaret Dobrowolska on PubMed
Spin-polarizable Excitonic Luminescence in Colloidal Mn2+-doped CdSe Quantum Dots Nano Letters. Apr, 2008 | Pubmed ID: 18331001 The photoluminescence of colloidal Mn2+-doped CdSe nanocrystals has been studied as a function of nanocrystal diameter. These nanocrystals are shown to be unique among colloidal doped semiconductor nanocrystals reported to date in that quantum confinement allows tuning of the CdSe bandgap energy across the Mn2+ excited-state energies. At small diameters, the nanocrystal photoluminescence is dominated by Mn 2+ emission. At large diameters, CdSe excitonic photoluminescence dominates. The latter scenario has allowed spin-polarized excitonic photoluminescence to be observed in colloidal doped semiconductor nanocrystals for the first time.
Giant Zeeman Splitting in Nucleation-controlled Doped CdSe:Mn2+ Quantum Nanoribbons Nature Materials. Jan, 2010 | Pubmed ID: 19915554 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 approximately 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.