The evolution of the electron spin dynamics as consequence of carrier delocalization in n-type GaAs is investigated by the recently developed extended pump-probe Kerr/Faraday rotation spectroscopy. We find that isolated electrons localized on donors demonstrate a prominent difference between the longitudinal and transverse spin relaxation rates in magnetic field, which is almost absent in the metallic phase. The inhomogeneous transverse dephasing time T2∗ of the spin ensemble strongly increases upon electron delocalization as a result of motional narrowing that can be induced by increasing either the donor concentration or the temperature. An unexpected relation between T2∗ and the longitudinal spin relaxation time T1 is found, namely that their product is about constant, as explained by the magnetic field effect on the spin diffusion. We observe a two-stage longitudinal spin relaxation which suggests the establishment of spin temperature in the system of exchange-coupled donor-bound electrons.
@article{arxiv.1712.02998,
title = {Electron charge and spin delocalization revealed in the optically probed longitudinal and transverse spin dynamics in $n$-GaAs},
author = {V. V. Belykh and K. V. Kavokin and D. R. Yakovlev and M. Bayer},
journal= {arXiv preprint arXiv:1712.02998},
year = {2017}
}