Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors

We report on a comprehensive combined experimental and theoretical study of Courie 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 Mn$_{Ga}$. Based on the analysis of magnetotransport and magnetization data we find 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 control. Modest charge compensation does not limit the maximum $T_{c}$ possible in ferromagnetic semiconductors based on (Ga,Mn)As. Ref: Jungwirth et al. Phys. Rev. B 72, 165204 (2005).