Antisite effect on ferromagnetism in (Ga,Mn)As

Authors:
  • RMR. C. Myers
    R. C. Myers
  • BSB. L. Sheu
    B. L. Sheu
  • AJA. W. Jackson
    A. W. Jackson
  • AGA. C. Gossard
    A. C. Gossard
  • PSP. Schiffer
    P. Schiffer
  • NSN. Samarth
    N. Samarth
  • DAD. D. Awschalom
    D. D. Awschalom
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Abstract
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.