Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 18: Joint Session "Magnetic Semiconductors" (jointly with HL)

MA 18.6: Talk

Tuesday, March 27, 2012, 10:45–11:00, H 0112

Multiband V-J model for dilute magnetic semiconductors — •Stefan Barthel¹, Gerd Czycholl¹, and Georges Bouzerar^2,3 — ¹Institute for Theoretical Physics, University of Bremen, Otto-Hahn-Allee 1, D-28359 Bremen, Germany — ²Institut Néel, 25 avenue des Martyrs, B.P. 166, 38042 Grenoble Cedex 09, France — ³School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 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.) is applied to the calculation of effective Mn-Mn exchange couplings J_ij. The pd-coupling is treated non-perturbatively and nonmagnetic scattering is included. A polynomial expansion of the spectral density allows for the study of orbital-resolved exchange couplings for very large system sizes, which can be directly mapped on a disordered Heisenberg model. Finally a comparison of our findings using realistic input parameters (bandstructure, impurity concentration, pd-coupling, impurity potential) to available ab-initio data (LDA, LDA+U) is made. Our approach seems promising to bridge the gap between model and ab-initio methods.