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MA: Fachverband Magnetismus

MA 30: Magnetic Semiconductors I

MA 30.4: Vortrag

Mittwoch, 16. März 2011, 11:45–12:00, HSZ 401

Reliable calculations of generalized RKKY-couplings for dilute magnetic semiconductors — •Stefan Barthel¹, Georges Bouzerar², and Gerd Czycholl¹ — ¹Institute for Theoretical Physics, University of Bremen, Germany — ²School of Engineering and Science, Jacobs University Bremen, Germany

A multiband empirical tight-binding model for magnetically doped group-III-V-semiconductors with zincblende structure (e.g. Ga_1−xMn_xAs, etc.) for the valence bands is applied to the calculation of generalized RKKY-couplings J_ij between magnetic impurities (e.g. Mn²⁺). Our approach does treat disorder exactly and enables a direct mapping on a disordered Heisenberg model to allow further studies. We will present analytic expressions of the double- and super-exchange terms in the limit of large splitting JS and show numerical results in the dilute regime for realistic parameters of doping concentration, hole density and impurity potential. Finally a comparison to results obtained by more sophisticated methods (Monte-Carlo simulations) is made and we will comment on the discrepancies, which will lead to different Curie temperatures.