This paper presents a study of electron spin dynamics in bulk GaAs at low temperatures for elevated optical excitation conditions. Our time-resolved Faraday rotation measurements yield sub-nanosecond electron spin dephasing-times over a wide range of n-doping concentrations in quantitative agreement with a microscopic treatment of electron spin dynamics. The calculation shows the occurrence and breakdown of motional narrowing for spin dephasing under elevated excitation conditions. We also find a peak of the spin dephasing time around a doping density for which, under lower excitation conditions, a metal-insulator transition occurs. However, the experimental results for high excitation can be explained without a metal-insulator transition. We therefore attribute the peak in spin-dephasing times to the influence of screening and scattering on the spin-dynamics of the excited electrons.
@article{arxiv.0902.0270,
title = {Ultrafast Spin Dynamics in Optically Excited Bulk GaAs at Low Temperatures},
author = {M. Krauss and R. Bratschitsch and Z. Chen and S. T. Cundiff and H. C. Schneider},
journal= {arXiv preprint arXiv:0902.0270},
year = {2015}
}