Observation of insulating nanoislands in ferromagnetic GaMnAs.
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.
Wang
D M
DM
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.
Ren
Y H
YH
Jacobs
P W
PW
Fahy
S
S
Liu
X
X
Furdyna
J K
JK
Sapega
V F
VF
Merlin
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R