We report on a systematic study of optical properties of (Ga,Mn)As epilayers spanning the wide range of accessible substitutional Mn_Ga dopings. The growth and post-growth annealing procedures were optimized for each nominal Mn doping in order to obtain films which are as close as possible to uniform uncompensated (Ga,Mn)As mixed crystals. We observe a broad maximum in the mid-infrared absorption spectra whose position exhibits a prevailing blue-shift for increasing Mn-doping. In the visible range, a peak in the magnetic circular dichroism blue shifts with increasing Mn-doping. These observed trends confirm that disorder-broadened valence band states provide a better one-particle representation for the electronic structure of high-doped (Ga,Mn)As with metallic conduction than an energy spectrum assuming the Fermi level pinned in a narrow impurity band.
@article{arxiv.1007.4708,
title = {Systematic study of Mn-doping trends in optical properties of (Ga,Mn)As},
author = {T. Jungwirth and P. Horodyska and N. Tesarova and P. Nemec and J. Subrt and P. Maly and P. Kuzel and C. Kadlec and J. Masek and I. Nemec and V. Novak and K. Olejnik and Z. Soban and P. Vasek and P. Svoboda and Jairo Sinova},
journal= {arXiv preprint arXiv:1007.4708},
year = {2015}
}