We construct a semimicroscopic theory, to describe the optical conductivity of Ga1-x Mnx As in the dilute limit, x∼1%. We construct an effective Hamiltonian that captures inside-impurity-band optical transitions as well as transitions between the valence band and the impurity band. All parameters of the Hamiltonian are computed from microscopic variational calculations. We find a metal-insulator transition within the impurity band in the concentration range, x∼0.2-0.3% for uncompensated and x∼1-3% for compensated samples, in agreement with the experiments. We find an optical mass mopt ≈ me, which is almost independent of the impurity concentration except in the vicinity of the metal-insulator transition, where it reaches values as large as mopt ≈10 me. We also reproduce a mid-infrared peak at ω≈200 meV, which redshifts upon doping at a fixed compensation, in quantitative agreement with the experiments.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Oct 7 2009|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics