Detection of large magneto-anisotropy of electron spin dephasing in a high-mobility two-dimensional electron system in a $[001]$ GaAs/AlGaAs quantum well

TL;DR

This study reveals a significant in-plane anisotropy in electron spin-dephasing times in a high-mobility GaAs/AlGaAs quantum well, with a factor of two difference depending on crystal direction, supported by microscopic calculations.

Contribution

The paper provides the first quantitative analysis linking spin dephasing anisotropy to Rashba and Dresselhaus effects in a high-mobility quantum well.

Findings

Electron spin-dephasing time varies by a factor of two between crystal directions.

Microscopic calculations accurately reproduce experimental anisotropy.

Estimated spin dephasing time along [110] is several nanoseconds.

Abstract

In time-resolved Faraday rotation experiments we have detected an inplane anisotropy of the electron spin-dephasing time (SDT) in an $n$--modulation-doped GaAs/Al$_{0.3}$Ga$_{0.7}$As single quantum well. The SDT was measured with magnetic fields of $B\le 1$ T, applied in the $[110]$ and $[1\bar{1}0]$ inplane crystal directions of the GaAs quantum well. For fields along $[1\bar{1}0]$, we have found an up to a factor of about 2 larger SDT than in the perpendicular direction. Fully microscopic calculations, by numerically solving the kinetic spin Bloch equations considering the D'yakonov-Perel' and the Bir-Aronov-Pikus mechanisms, reproduce the experimental findings quantitatively. This quantitative analysis of the data allowed us to determine the relative strengths of Rashba and Dresselhaus terms in our sample. Moreover, we could estimate the SDT for spins aligned in the $[110]$ {\em inplane} direction to be on the order of several nanoseconds, which is up to two orders of magnitude larger than that in the perpendicular {\em inplane} direction.