Response properties of III-V dilute magnetic semiconductors: interplay of disorder, dynamical electron-electron interactions and band-structure effects

摘要

A theory of the electronic response in spin and charge disordered media isdeveloped with the particular aim to describe III-V dilute magneticsemiconductors like GaMnAs. The theory combines a detailed k.p description ofthe valence band, in which the itinerant carriers are assumed to reside, withfirst-principles calculations of disorder contributions using anequation-of-motion approach for the current response function. A fully dynamictreatment of electron-electron interaction is achieved by means oftime-dependent density functional theory. It is found that collectiveexcitations within the valence band significantly increase the carrierrelaxation rate by providing effective channels for momentum relaxation. Thismodification of the relaxation rate, however, only has a minor impact on theinfrared optical conductivity in GaMnAs, which is mostly determined by thedetails of the valence band structure and found to be in agreement withexperiment.