Ultrafast Spin Dynamics in Optically Excited Bulk GaAs at Low Temperatures

Abstract

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.

7 pages, 3 figures, revised

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• Hole spin relaxation in intrinsic and $p$-type bulk GaAs
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• Hole spin relaxation in $p$-type (111) GaAs quantum wells
• Multivalley spin relaxation in $n$-type bulk GaAs in the presence of high electric fields
• Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium
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