Dependence of spin dephasing on initial spin polarization in a high-mobility two-dimensional electron system

Abstract

We have studied the spin dynamics of a high-mobility two-dimensional electron system in a GaAs/Al_{0.3}Ga_{0.7}As single quantum well by time-resolved Faraday rotation and time-resolved Kerr rotation in dependence on the initial degree of spin polarization, P, of the electrons. By increasing the initial spin polarization from the low-P regime to a significant P of several percent, we find that the spin dephasing time, $T_2^{\ast }$, increases from about 20 ps to 200 ps; Moreover, $T_2^{\ast }$ increases with temperature at small spin polarization but decreases with temperature at large spin polarization. All these features are in good agreement with theoretical predictions by Weng and Wu [Phys. Rev. B {\bf 68}, 075312 (2003)]. Measurements as a function of spin polarization at fixed electron density are performed to further confirm the theory. A fully microscopic calculation is performed by setting up and numerically solving the kinetic spin Bloch equations, including the D'yakonov-Perel' and the Bir-Aronov-Pikus mechanisms, with {\em all} the scattering explicitly included. We reproduce all principal features of the experiments, i.e., a dramatic decrease of spin dephasing with increasing $P$ and the temperature dependences at different spin polarizations.

8 pages, 8 figures, to be published in PRB

References in corpus (7)

• High temperature spin dephasing in n-typed GaAs quantum wells
• Effect of initial spin polarization on spin dephasing and electron g factor in a high-mobility two-dimensional electron system
• Enhanced spin relaxation time due to electron-electron scattering in semiconductors
• Hot-electron effect in spin dephasing in $n$-type GaAs quantum wells
• Spin relaxation in $n$-type GaAs quantum wells from a full microscopic approach
• Detection of large magneto-anisotropy of electron spin dephasing in a high-mobility two-dimensional electron system in a $[001]$ GaAs/AlGaAs quantum well
• Hole spin dephasing in $p$-type semiconductor quantum wells

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