For the s-f model in ferromagnetic semiconductors, it is necessary to treat simultaneously multiple scattering on the same site and scattering due to f spin correlation between different sites. In this paper, one-site multiple scattering is taken into account using a t-matrix formalism, and the exchange scattering via f spin correlation between different sites is treated using a two-spin correlation function and an appropriate decoupling scheme. The results show good agreement with those of the coherent potential approximation in the high-temperature limit. The calculated energy of the bottom of the band is reasonable, even at the Curie temperature (${\mathit{T}}_{\mathit{C}}$), for a wide range of IS/W, where W is the bandwidth of the conduction band and IS is the exchange interaction energy.

• Received 31 July 1995

DOI:https://doi.org/10.1103/PhysRevB.52.16313