Dielectric response in narrow-gap semiconductor quantum wells in a magnetic field

A multiband theory of the dielectric response in a quasi-two dimensional (Q 2D) electron plasma of narrow-gap semiconductor structures in an external m agnetic field has been developed. The strong interband mixing plays an esse ntial role in the determination of the shape and behavior of the dielectric response in narrow-band Q2D systems. We have used a full 8 x 8 k.p Hamilto nian model to describe the Landau levels. A rigorous theoretical analysis s hows, among other interesting features, that spin-flip-like intrasubband tr ansitions are allowed and its effects on the related optical properties of Q2D systems are investigated. The influence of the Landau level filling fac tor on the dielectric response and the limit of integer and fractional fill ing factors cases are discussed. We found that the occupation of Landau lev els modulates the polarizability strength of the plasma. (C) 2001 American Institute of Physics.