Wang, DM,Ren, YH,Jacobs, PW,Fahy, S,Liu, X,Furdyna, JK,Sapega, VF,Merlin, R

2009

June

Physical Review Letters

Observation of Insulating Nanoislands in Ferromagnetic GaMnAs

Validated

()

ELECTRONIC-STRUCTURE BULK GAAS MN GA1-XMNXAS SEMICONDUCTORS SPECTROSCOPY TEMPERATURE ACCEPTOR RAMAN

102

Resonant Raman data on ferromagnetic GaMnAs reveal the existence of a new kind of defect: insulating nanoislands consisting of substitutional Mn(Ga) acceptors surrounded by interstitial Mn(I) donors. As indicated by the observation of a sharp 1S(3/2)-> 2S(3/2) Raman transition at similar to 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 Mn(I) ions.

10.1103/PhysRevLett.102.256401