Detection of large in-plane spin-dephasing anisotropy in [1 0 0]-grown GaAs/AlGaAs quantum wells

The electron density-dependent in-plane spin dephasing anisotropy in GaAs/AlGaAs single quantum wells has been investigated by time-resolved magneto-Kerr rotation (TR-MOKE) measurements. Large anisotropy of in-plane spin dephasing time has been observed and compared for samples with different degrees of structural asymmetry. The breakdown of spin dephasing anisotropy with increase in electron density is ascribed to the combined effect of relative strength change in the Rashba and Dresselhaus fields and contribution of cubic Dresselhaus term at higher excitation electron density. It is revealed that Dresselhaus spin–orbit coupling strength is stronger than Rashba for all samples studied in our experiment. The measured anisotropy dependence on electron density and sample asymmetry agrees with previous theoretical studies.