Calculating the Curie temperature reliably in diluted III-V ferromagnetic semiconductorsG. Bouzerar1, T. Ziman1 and J. Kudrnovský2
1 Institut Laue Langevin - BP 156, 38042 Grenoble, France
2 Institute of Physics, Academy of Sciences of the Czech Republic Na Slovance 2, CZ-182 21 Prague 8, Czech Republic
received 17 December 2004; accepted in final form 14 February 2005
published online 16 February 2005
We present a semi-analytic theory for the Curie temperature in diluted magnetic semiconductors that treats disorder effects exactly in the effective Heisenberg Hamiltonian, and spin fluctuations within a local RPA. The exchange couplings are taken from concentration-dependent ab initio estimates. The theory gives very good agreement with published data for well-annealed samples of MnxGa1-xAs. We predict that critical temperatures for strongly p-type MnxGa1-xN would be lower than in doped GaAs, despite the stronger nearest-neighbour ferromagnetic coupling. We also predict the dependence on the hole concentration.
75.50.Pp - Magnetic semiconductors.
75.47.-m - Magnetotransport phenomena; materials for magnetotransport.
71.55.Eq - III-V semiconductors.
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