Wang DM, Ren YH, Jacobs PW, Fahy S, Liu X, Furdyna JK, Sapega VF, Merlin R. Observation of insulating nanoislands in ferromagnetic GaMnAs.
Phys Rev Lett 2009;
102:256401. [PMID:
19659101 DOI:
10.1103/physrevlett.102.256401]
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Abstract
Resonant Raman data on ferromagnetic GaMnAs reveal the existence of a new kind of defect: insulating nanoislands consisting of substitutional MnGa acceptors surrounded by interstitial MnI donors. As indicated by the observation of a sharp 1S3/2-->2S3/2 Raman transition at approximately 703 cm(-1), the acceptor-bound holes inside the islands are isolated from the metallic surroundings. Instead, Mn-bound excitons do couple to the ferromagnetic environment, as shown by the presence of associated Raman magnon side bands. This leads to an estimate of 5-10 nm for the nanoisland radius. The islands disappear after annealing due to the removal of the MnI ions.
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