We study the Curie temperature and hole density of (Ga,Mn)As while systematically varying the As-antisite density. Hole compensation by As-antisites limits the Curie temperature and can completely quench long-range ferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by molecular beam epitaxy without substrate rotation in order to smoothly vary the As to Ga flux ratio across a single wafer. This technique allows for a systematic study of the effect of As stoichiometry on the structural, electronic, and magnetic properties of (Ga,Mn)As. For concentrations less than 1.5% Mn, a strong deviation from Tc ~ p^0.33 is observed. Our results emphasize that proper control of As-antisite compensation is critical for controlling the Curie temperatures in (Ga,Mn)As at the low doping limit.
@article{arxiv.cond-mat/0606488,
title = {Antisite effect on ferromagnetism in (Ga,Mn)As},
author = {R. C. Myers and B. L. Sheu and A. W. Jackson and A. C. Gossard and P. Schiffer and N. Samarth and D. D. Awschalom},
journal= {arXiv preprint arXiv:cond-mat/0606488},
year = {2007}
}