Theory of free-carrier magnetoabsorption in mixed zincblende narrow-gap semiconductors

The influence of chemical disorder on the magneto-optical properties of mixed semiconductors with zincblende structure and dispersion relations typical of III-V and II-VI compounds is considered theoretically. The magneto-optical transitions between Landau levels are described, treating the potential due to the chemical disorder as a perturbation. It is found that all transitions between any two Landau levels are allowed (Δn >= 2). The absorption coefficient is non-vanishing for any polarization and frequency due to the presence of chemical disorder. For parallel and perpendicular light polarization additional Kohn or logarithmic-like divergencies of the absorption coefficient are obtained at phonon energies equal to (h/2π)ω = E/sub n//sup +-/ - E0+. (author)