Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors
Abstract
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 Tc in high-quality metallic samples increases linearly with the number of uncompensated local moments on MnGa 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 MnI positions act as double-donors and compensate neighboring MnGa local moments because of strong near-neighbor MnGaMnI antiferromagnetic coupling. These defects can be efficiently removed by post-growth annealing. Our analysis suggests that there is no fundamental obstacle to substitutional MnGa 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.
- Publication:
-
Physical Review B
- Pub Date:
- October 2005
- DOI:
- 10.1103/PhysRevB.72.165204
- arXiv:
- arXiv:cond-mat/0505215
- Bibcode:
- 2005PhRvB..72p5204J
- Keywords:
-
- 75.50.Pp;
- 75.30.Gw;
- 73.61.Ey;
- Magnetic semiconductors;
- Magnetic anisotropy;
- III-V semiconductors;
- Condensed Matter - Materials Science
- E-Print:
- 13 pages, 12 figures, submitted to Phys. Rev. B