Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors
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We report on a comprehensive combined experimental and theoretical study of Curie temperature trends in (Ga,Mn)As ferromagnetic semiconductors. Broad agreement between theoretical expectations and measured data allows us to conclude that T-c in high-quality metallic samples increases linearly with the number of uncompensated local moments on Mn-Ga acceptors, with no sign of saturation. Room temperature ferromagnetism is expected for a 10% concentration of these local moments. Our magnetotransport and magnetization data are consistent with the picture in which Mn impurities incorporated during growth at interstitial Mn-I positions act as double-donors and compensate neighboring Mn-Ga local moments because of strong near-neighbor Mn-Ga-Mn-I antiferromagnetic coupling. These defects can be efficiently removed by post-growth annealing. Our analysis suggests that there is no fundamental obstacle to substitutional Mn-Ga doping in high-quality materials beyond our current maximum level of 6.8%, although this achievement will require further advances in growth condition control. Modest charge compensation does not limit the maximum Curie temperature possible in ferromagnetic semiconductors based on (Ga,Mn)As.
DescriptionJournals published by the American Physical Society can be found at http://journals.aps.org/
SubjectDILUTED MAGNETIC SEMICONDUCTORS
V COMPOUND SEMICONDUCTORS
QUALITY GAMNAS FILMS