Optical conductivity of Mn doped GaAs

Abstract

We study the optical conductivity in the III-V diluted magnetic semiconductor GaMnAs and compare our calculations to available experimental data. Our model study is able to reproduce both qualitatively and quantitatively the observed measurements. We show that compensation (low carrier density) leads, in agreement to the observed measurements to a red shift of the broad peak located at approximately 200 meV for the optimally annealed sample. The non perturbative treatment appears to be essential, otherwise a blueshift and an incorrect amplitude would be obtained. By calculating the Drude weight (order parameter) we establish the metal-insulator phase diagram. We indeed find that Mn doped GaAs is close to the metal-insulator transition and that for 5 and 7 doped samples, 20 of the carriers only are delocalized. We have found that the optical mass is approximately 2 m${}_e$. We have also interesting results for overdoped samples which could be experimentally realized by Zn codoping.

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• Infrared conductivity of hole accumulation and depletion layers in (Ga,Mn)As- and (Ga,Be)As-based electric field-effect devices
• Magnetic spin excitations in Mn doped GaAs : A model study
• Effective Heisenberg exchange integrals of diluted magnetic semiconductors determined within realistic multi-band tight-binding models