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Effect of initial spin polarization on spin dephasing and electron g factor in a high-mobility two-dimensional electron system

D. Stich·J. Zhou·T. Korn·D. Schuh·W. Wegscheider·M. W. Wu·C. Schüller
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Abstract

We have investigated the spin dynamics of a high-mobility two-dimensional electron system (2DES) in a GaAs--Al$_{0.3}$Ga$_{0.7}$As single quantum well by time-resolved Faraday rotation (TRFR) in dependence on the initial degree of spin polarization, $P$, of the 2DES. From $P\sim 0$ to $P\sim 30$ %, we observe an increase of the spin dephasing time, $T_2^\ast$, by an order of magnitude, from about 20 ps to 200 ps, in good agreement with theoretical predictions by Weng and Wu [Phys. Rev. B {\bf 68}, 075312 (2003)]. Furthermore, by applying an external magnetic field in the Voigt configuration, also the electron $g$ factor is found to decrease for increasing $P$. Fully microscopic calculations, by numerically solving the kinetic spin Bloch equations considering the D'yakonov-Perel' and the Bir-Aronov-Pikus mechanisms, reproduce the most salient features of the experiments, {\em i.e}., a dramatic decrease of spin dephasing and a moderate decrease of the electron $g$ factor with increasing $P$. We show that both results are determined dominantly by the Hartree-Fock contribution of the Coulomb interaction.

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D. Stich, J. Zhou, T. Korn, D. Schuh, W. Wegscheider, M. W. Wu, C. Schüller. 2007-03-28. Effect of initial spin polarization on spin dephasing and electron g factor in a high-mobility two-dimensional electron system. https://doi.org/10.1103/physrevlett.98.176401

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